I was at my local dealer getting some supplies for the big three and they told me that you will still need a high output alt. even though you're just adding wires for current flow. They said they do this upgrade daily and people just get the upgrade and no alt., and they end up breaking down because their alt. is dead. I have a little light dim and wanted to fix it with a four guage big three but want to check with people I know are educated with this.I mean I've read a lot of how to's and surfed around checking into this and never heard of this problem.All that is actually going on is a larger wire for more current flow,right?
Replies (21)
ttocs on 09/25/2006 16:06:09
it will not hurt anything. upgrading your alt also, will not hurt anything. You are not adding current or voltage to the system, just making it easier to move around which can free up a few volts....
anonymous_a on 09/25/2006 16:32:23
Thats what I thought just wanted to be extra sure though, thank you ttocs.
MrBrownstone on 09/25/2006 17:20:50
Whether or not to add an aftermarket (or upgraded) alternator has been a topic of recent debate. For the most part, unless you are competing in a DB Drag competition whereas you'll need 16V, or need 200Amps current, I just don't see the need for most daily drivers.
A fair rule of thumb should be usage and available current. I used 1400W (1kW sub amp + 400W 4ch) and the need for an alternator upgrade wasn't necessary. The car, was a 1989 Toyota Corolla...and we know how small those alternators are.
It really depends upon the type of vehicle you are using, and the power you'll be using. Remember, amplifiers only use maximum current when you are running them at maximum output...and how often is that?
swez on 09/26/2006 11:08:00
Today's vehicles are pretty complex and all the electronics used for engine, body, ABS and fuel monitoring systems, need a well regulated power supply system. If we overload them regularly with aftermarket add ons, but do not compensate for that, things can and do go south.
A case study: My Dad bought a Ford F-350 Turbo Diesel "Dually" with a HD towing. (160A, dual BATs) He had a local shop install remote start, alarm and air horns. Within a few weeks, odd things began to crop up:
1. The auto-sense headlight delay circuit failed
2. The horn relay and associated control module failed
3. A remote BAT charging circuit for the towed trailer fried out too
Each situation was related to improperly installed aftermarket add ons by some inexperienced tech, who did not know what he was doing. This shop was not able to troubleshoot the root causes. So, they disabled given features and sent the truck over to a dealership for repairs.
In all, this truck has been in the shop or off the road for several days on each issue noted above. The point here, this truck is made for HD service. However, improper install techniques on the aftermarket gadgets and gizzmos.
OK, what's the point this ol fart (swez) is trying to make here? Well, today's techs need to be VERY SKILLED and up to date on these complex vehicle packages. One cannot just slap things in w/o considering the overall effects to a factory setups.
End Rant!
Now, based on Anon's scenario, I agree with ttocs... an ALT/BAT upgrade is good insurance against premature electrical failures when using high powered audio add ons. A lot depends on the istall process and how one uses this gear later.
Yes, the Big 3 wiring upgrade allows more efficient flow of power in the electrical system. Larger wires have less resistance and can take more power than a typcial factory wiring kit. However, depending on how one installs and uses a high power audio system, this kit can easily overload the factory ALT/BAT and affect the entire electrical system.
Usually, the ALT will have abnormal power demands placed upon it and the life cycle will be much shorter than the system was originally designed for. Light dimming is a minor concern and yes, this can be reduced or eliminated with wiring upgrades in many cases.
But, if we use a stock ALT, make it run at 80-110% of its design capability on a long term basis, expect the ALT to fail, well before its time. That's the main reason we do this expensive upgrade. Basically, use the right tools for the job and all is well.
FYI: As a professional contractor for several years now, we cannot buy cheap DIY power tools. They cannot stand up to the heavy use and reliabilty factors we demand from Pro Grade tools. Yes, these tools are more expensive initially... but when your at a job site and pressing tools to their limits a lot, a field failure of a given tool is not just an inconveinece... it's a show stopper. That's lost time, productivity and may affect other contractors schedules as well. (For most GC's, that's not acceptable) But, we do carry backup tools for this very reason.
In this case, the worst scenario would be an electrical failure that leaves one stranded, (miles from home) and needing road side towing and/or repairs. That service is not cheap and we eventually wind up buying H.D. parts later anyway. So, to prevent this, we take appropriate steps to prevent such things.
swez
PS Mr. B has a good point and he probably did not abuse, (Read abnormal use) of his 89 Toyota and the gear installed. It may have worked just fine for years when using said gear at moderate demand levels. However, todays vehicles are far more complex. If we push our aftermarket systems hard for long periods of time w/o some degree of upgrades and compensations, be prepared for un-timely failures.
MrBrownstone on 09/26/2006 15:57:21
I believe that the reason your father had trouble was FORD. Electronics from the 'big 2' automakers in America are built problematic on purpose...to sell parts.
As far as my car, I hammered the hell out of that thing...for 95,000 of it's miles and didn't even need to replace alternator brushes. If your electronics fail, it's not the STEREO's fault, it's the carmaker.
Let's be real, if you are using <1000 watts, you don't need an alternator. Starting between 1kW & 2kW, there's benefit. so unless the guy is using more than 1kW, there's no need to continue this discussion.
How much power do you believe you'll be using, Anonymous?
Victor on 09/26/2006 16:48:33
alt or no alt... doesnt in actually depend on what kinda stock electricals does the amnufacturer supply.. here in india most cars have a stock alt of max 60-80 amps.. hehe.. now dont we need an alt upgrade???
anonymous_a on 09/26/2006 19:54:00
Well for now its just Rockford P6002(80 amps) Visonik amp(20 amps) Soundstorm SSL crossover(3 amps). For now the power hog is the Rockford but I may upgrade to a P8002,JBL 1200, or Infinity 1200. All three of those have three 40 amp fuses.As for now I have minimal light dimming and thought I'd take a couple of dollars and minutes to solve the problem.I do know overall a powerfull setup may shorten the alternator's life. The only reason I asked because the installer seemed so sincere about this.He acted like in order to think about "the big three" you needed to have a h.o. alternator and battery first. Then he said you didn't need to fuse the alternator to battery wire. After this little discussion got my supplies and left.Through all the websites,threads, how to's,pics,etc, I knew what the deal was but just wanted the extra input on the matter.(P.S.)How do you start a new paragraph?
swez on 09/26/2006 22:13:16
(P.S.)How do you start a new paragraph?
Use the enter button on your computer.
I believe that installer was giving a straight answer about power management issues. Here's why...
Let's say we have a give circuit in our home. It has a 14 gage wire attached to a fuse or circuit breaker in the main panel and that value is 15 amperes. Here, we are working with 120 volts AC and a current limit factor of 15 amperes. (120 x 15 = 1800 watts)
Now, suppose we grab a 6 socket plug in box and started adding devices to that plug in strip.... what will happen as we turn on these things?
1. A 150 watt light bulb: (1.25 amperes draw) AOK
2. A 1500 watt hair dryer: (11.7 A's @ high settings) Still OK
3. A 250 watt TV set: (2.1 A's) Circuit failure dude!!!
The fuse or breaker will trip out with only 3 devices as we have exceeded the current limits that line can handle. Yes, the breaker or fuse may take a few minutes to trip out, but it WILL TRIP OUT!!!
Now, in a vehicle, we also have fuses, specific wire gages for a given set of circuits and a finite amount of power in the supply feed off the ALT & BAT. The main difference here, we are dealing with low DC voltage values (12.5 - 14.4 volts DC) and "X" amount of current available from the ALT and BAT. When we add high powered add on to a stock system, sooner or later, something has to give, if we constantly demand more power from the overall system then it waas designed for right?
OK, let's take a closer look at what goes on in a car system. For example, let's start with a basic set of round numbers:
ALT: A 100 amp rated ALT will produce about 13.8 volts and up to 100A's of current at engine RPM's of 2000 or higher. At idle, this ALT can do about 50-55A's well.
Q1: What is the nominal and maximum wattage this ALT will produce at idle and >2000 RPM?
A1. 13.8 volts x 55 A's = 759 watts nominal, at engine idle speed
A1a. 13.8 volts x 100 A's = 1380 watts nominal at >2000 RPMs
Alrighty then, we now know the nominal and maximum power output capacity of this ALT. The ALT provides all electrical power to all car devices, once the engine is started. However, its first order of business, is to charge back up the BAT to a fully charged state.
A car BAT is rated at 12.5 volts DC at full charge. A typical BAT will provide 500 - 1000 Cold Cranking Amperes (CCA's) when we start the vehicle. The BAT provides adequate power to the starter and basic system components to get the engine to run properly. The more power we use to start the engine, the longer it takes the charging circuit and regulator to bring the BAT back up to full charge. (This may take ~4-10 minutes, depending on the BAT drain)
Once the engine is running smoothly, look at the charging voltage used to top off the BAT again. (Typ. 14.4 volts and as much current as is possible, to bring the BAT back up to full charge) This may take a few minutes and then, the charging circuit, (ALT and regulators) will slowly drop voltage and current demands from the ALT, as the BAT returns to normal full charged state.
FYI: When the BAT is fully charged again, voltage and current demands from the ALT are normalized and we typically see a steady voltage reading at the BAT of roughly 13.8 volts. (+/- 0.5 volts)
Got all that so far?
Anyone care to dispute this one... if so, feel free to show your lack of undertanding for all to see. hehe.. (Who's gonna bite on that hook?)
OK, now the BAT is fully charged again and the ALT goes back to cruisin' mode until we flip on a few devices like head lights, blower motor, adjust power seats, mirrors, depress the brake peddle and watch a few more lamps fire up. So far, no problems as the ALT is ready to carry these new loads. Here, the charging system now relies 100% on the ALT's power output. As we step on the gas peddle and move out, ALT power will increase as needed to keep all devices adequately powered.
Ok, now we are motoring down the road. All systems are normal and the load the ALT sees, is based on adding up power draws from all main default devices and other main circuits we need at that moment. The big wattage circuits we often use are headlights, blower motor for HVAC, side marker lamps, instrument panel displays, ECM/BCM, ABS circuits and rear window defoggers. Here, power windows, door locks, seat motors and the like, are only momentary loads. When we get them adjusted to our liking, they no longer use power.
OK, this is installment #1 on this topic for now. I will add a few more things later and continue the tuitorial as I have time. Just know we have just began this process and things get a lot more complex when we start adding AUX power devices into the mix....
Stay tuned for Part II,
Swez
PS For Annon, use the enter bar on your keyboard to start a new paragraph OK... Thanks bro... SMILE
swez on 09/29/2006 10:18:26
Part II, the BATTERY as a helper.
OK, we have discussed the function of the Alternator. Now, let's look at the Battery aspects of a given system.
The BAT is a power storage device. When fully charged, we see about 12.5 volt DC power source. As for current capacities, this is variable based on the size of the battery, # of plates used, thickness of storage plates and the type of electrolyte used.
The most common car battery is a wet cell, lead-acid battery. We are now seeing a steady influx of new battery technologies that employ gelled electrolytes, (Gel Cells) and some hybrids that use a combination of wet and gel cell technologies.
Anyway, back to the basics... a lead-acid battery consists of many thin plates, grouped together in multi-celled chambers. They are rated in Ampere hours and the larger the battery package is, the more Ampere hours they can deliver.
The general functions of a car battery are:
1. Starting the engine
2. Powering electronic devices w/o the engine running (short term)
3. A power storage reserve
When we jump into the car and turn the key to start the car, the battery takes a pretty large hit of surge drain as the starter engages and cranks the engine over. In a small engine, (2.0 Liters or less) this surge may be as little as 100 -150 amperes of current surge in a 5-10 second period. For a large V-6 or V-8 engine, that surge might be as high as + 300 amperes for a short duration. That's why we see tiny batteries in very small engines and large battery packs in larger engines.
Once the engine starts, the Alternator takes over and begins to recharge the depleted battery and power the rest of the vehicles' needs. This recharging state will last as long as the battery is below rated voltage and demanding power to refill itself to a balanced condition. Here, the voltage regulator in the charging circuit will allow higher voltages from the Alt to flow to the Bat and other electrical components as needed. This high voltage condition, (~14.4 volts) will remain as long as the Bat is recharging.
When the Bat is adequately charged, the regulator circuits sense the system is now back to normal and the Alt will return to normal operating conditions of between 13.5 - 13.8 volts and deliver as much current as needed to feed all active circuits. Are we tracking together so far?
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Now, suppose we added a few large power devices, (Amplifiers,Aux lighting, CB radio Kickers, etc.) a given factory electrical system. How do those devices play out their roles in a given scenario?
Well, when not in use, these devices do nothing and don't affect the system at all. However, when we activate them and dial up the power demands on the electrical system at large, they draw watts from the system as needed and can become substantial loads on a given stock electrical system. Depending on how much power we demand them to generate, this determines how large the load will be on the charging system.
A modest audio system of say 300 watts, will not put any major strain on the electrical system. At full output power, the electrical system can easily manage this type of load. Depending on the amp technology used, (Class D sub or Class A/B designs) we are looking at a range of current draw between 25 - 35 amperes of current draw. Here, let's assume the worst case scenario, the amplifier is at full power and using high duty cycle test tones. The amp is working hard, but the electrical draw from the system is modest and easily managed. So far, so good huh?
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Now, let's change the scenario and add a few potent amplifiers. This changes the game considerably. As an example, let's say we have a 500 watt Class D amp for the sub(s) and a 300 watt amp (75 x 4) for mid/highs. How will this combination of amps affect the electrical system? Depending on how we use them, it could be minimal or the affect can be substantial. The scenario:
1. Class D amp, 500 RMS (~80% efficiency rating)
2. Class A/B amp, 300 RMS (~60% efficiency rating)
The worst case scenario is that we are using high duty cycle test tones as the audio content. Let's say we are dialing in the amps for maximum RMS output and putting the system to its biggest test. Basically, we are pushing the audio system to maximum performance and as such, the amps are working at full capacity. What's the electrical load we can expect under these conditions?
A. The 500 RMS sub amp is pretty efficient (80% eff) and will draw "X" amount of watts under full load test conditions. Here are the numbers
we can anticipate under test conditions:
500/.80 (eff) = 625 watts
625 watts / 13.5 (ref supply voltage) = 46.3 amperes
Pretty strong current pull huh? You bet... and the stock electrical system is going to work pretty hard to manage that load too.
B. The 75 x 4, Class A/B amp delivers about 300 watts RMS at full power. How much power does it consume?
300/.60 (eff) = 500 watts
500/13.5 (ref supply voltage) = 37.0 amperes
Now, add them up... 46.3 + 37.0 = 83.3 amperes total
Hummm, that's about 1125 watts consumed to produce 800 watts of audio output power. That's enough wattage draw to run a 1.5 HP DC electric motor. (746 watts = a 1.0 Horse Power load) Whoa.... now we are talking some serious power consumption here right?
**************************************************************************
As we can plainly see, this type of rig is capable of consuming considerable current from a meager factory supply system. How does a 100A ALT and a typical 600 CCA BAT handle such an adverse load?
I will stop here for now and pick up on the subject later. Digest this information, mull it over and THINK about what all this means in broad terms. The goal here, is to make one think about how large power amps can affect the stock electrical system of any given vehicle.
Happy reading,
swez
MrBrownstone on 09/29/2006 22:20:52
I agree with Victor...earlier...
"alt or no alt... doesnt in actually depend on what kinda stock electricals does the amnufacturer supply.. here in india most cars have a stock alt of max 60-80 amps.. hehe.. now dont we need an alt upgrade???"
If your lights dim, and it bothers you, get a capacitor ( or several). There isn't a lot of science indicating that you'll hear any difference, but at least the amount of dimming will either be reduced or go away. An upgraded alternator will also provide more current, but you need to make certain that the upgraded alternator puts out more at idle...not at higher RPMs or it won't make much difference.
What happens is when your accessories (car audio included) use more current than the alternator can provide, voltage drops. This is why the lights dim. As soon as the load eases, the lights come right back.
Unless your lights dim, and do NOT return to brightness, you don't need an alternator upgrade. You may DESIRE one if you intend to enter a car audio competition, but for daily driving, It's just not necessary.
On a side note: the system you are talking about is so small I doubt that there's enough current draw worth arguing about. Get me to 2kW output, then we're talking. Get me to 3kW, or a competition system such as DB DRAG, then an alternator is needed.
swez on 09/30/2006 01:24:37
Well, 2 KWatts are a lot off juice to ask of a stock system if doing more than a few seconds of "burp tones". If a 100A Alt can deliver 14.4 volts. That's 1440 watts or 1.44 KW continous so far.
A 2 KW Class D (80% eff) will draw about 2.5 KW at full power w/o clipping. If we allow for 10% clipping or more, that KW draw # is even larger for the duration of the burp. This tells me the BAT (or several Bat's will) have to make up the difference. A Bat can deliver a 300A burst for some duration of time. (300 x 12.5 = 3.75 KW) The question in my head is... How long can a system take that kind of load and how long does it take to recharge a BAT after such a hit?
Yeah, I may be barking up a dead tree here... but allow me an opportunity to figure this out. I am willing to make a few mistakes and learn something here. Learning new ideas (or old lessons that others have already mastered) often requires a few broken yokes. In any event, the yokes on my face and since I am a grown man, I can wipe it off if that point comes along later.
I agree about the light dimming part... no problems with that. As you say, it's just a momentary lag in voltage drop as the amp draws this spiked amount of power from the charging system. I get that well enough.
However, noone run their lights in a Burp/Fart tone test right? That's just raw power off the ALT and BAT(s) combined. But what about a daily driver that's pushing 2KW's of amping power and also serving up other loads that add another 0.75 KW.
To my present reckoning, a few hours of commuting with all this going on, is a pretty tall order to fill. Something has to give, sooner or later right? What's missing in this scenario? Or, what erronous assumptions am I over looking here? That is what is pickling me???
swez
PS Yes, I am trying to deceifer a strange code here. "it just works that way" is not the only answer I am looking for. (Or is that the point I fail to see???) Puzzled in Detroit...
PSS Besides, The Tiger's lost to KC Royals tonight and now, they have to slug it out in the numbers game with the Twins and them damn Yankees for a chance at the Central Divison pennant and a wild card slot for the World Series. Who cares right? Least of all... me! But Deee-troit needs some good news this year and the Tiger's have a long shot at it. So, with baited breath, we wait some more. hehe
MrBrownstone on 10/2/2006 00:04:46
Well, in the above example, noone is using 2kW and noone is using continuous power at 100% RMS!!! When we get to 2kW, more to talk about. At this juncture, there's just nothing to talk about.
Your current calculations are assuming that the electrical system and the amplifier are like a firehose. They are not, more like a sprinkler with 3/4 second pauses. 3/4 of each second, the output on your amplifier is resting...catching up....otherwise, the car would stop running or the amp would shut off.
swez on 10/2/2006 08:56:03
Was thinking more along the lines of a variable load model too. Like your analogy of a fire hose, but VS a pulse type sprinkler system.
Are you sure noone listens to their systems at high power all the time? Judging from what I see/hear in this hood, I beg to differ. I live ~1/4 mile from our local High School. I know when they get out of school 'cause I can hear them from at least 2 blocks away.
Same thing at stoplights, gas stations and the 7/11's. These idiots charge up and down the residential area like they are the only peeps in town. They leave their rigs on and boomin' while getting gas and charging up their 64 oz Slurppies.
I have been tempted to ask them to show me thier gear at times... then when they do, I'd reach in and yank the livin' crap on the power leads to thier amps. Then, for insurance, I'd short that sucker to the amp casing and put them out of biz for a long time. Imagine that... arch welding the power cable to the amp casing... hummm, wonder how that would work out huh?
In short, some guys have no clue how irritating their behavior is to others who don't like "C-RAP" music.
Ahhhh, I feel better now. Thanks for letting me vent!!! END RANT
swez COFFEE
MrBrownstone on 10/2/2006 16:45:02
hee Hee....C-RAP. A swez original from 1988. :-)
Listening to your system at 100% or 100%?
100% loudness, yes
100% of amplifier's capabilities...NO
There's just no way you could tolerate the total 100% distortion all the time. 115% of RMS rating, sure..but distortion would be so highly audible...and undesireable that I doubt it.
Even then, we're not talking 100% of the amplfier's usage, and when we are...we're talking for 1/4 of real time. That gives our alternator 3/4 of a second to reload.
Think of it as a TV weather radar. They broadcast 250,000 W to 1MW of power...but if they did it continuously, there's be melted birds allover the countryside withing a 100 foot area.
Divide your current load numbers by 4...because that's what the alternator sees. At 100% clipped signal (250% RMS power) yes, it's seeing 100%
END terminology parsing.
Victor on 10/2/2006 17:22:37
dunno whats up with dave.. but he sure is writing a lot these days..forget paragraphs... he's writing essays.... and this particular alternator thingy has really churned up something inside him...
swez on 10/2/2006 19:37:51
Yes, I am trying to get something out of this whole issue. The part I am struggling with is the thought that amps work on a 25% duty cycle.
Have heard that statement many times form Mr. B and I'd like to see it from another reputable source. If I read it in a trade magazine and it had Dave Navone or Richard Clark's name on it, I'd buy it, sell it and just shut up already.
Liked your Microwave analogy there B. There is talk of developing solar power stations in a geo-sync orbit. They are thinking about many large solar cell arrays up in space, coupled with a microwave transmitter to beam energy back to a target on earth. The trick is the beam diameter to use.
A narrow and coherant beam is too intense and concentrated for safe use. However, if the beam were several meters in diameter, the energy per cubic meter would be safe for planes, people, wildlife and such, not to get vaporized. Cool idea huh? Sure, they could do a hard wire drop too... but many miles of power cable are expensive, dangerous and cannot support its own weight.
B... Just show me where I can find out more about Duty Cycles on audio amplification factors. If that is possible and I can understand it... I'll shut up and go back to sleep.... Whaaaaah GRIN
Swez
Victor on 10/3/2006 02:14:04
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1760
http://sound.westhost.com/articles/pwm.htm
http://members.tripod.com/valveaudio/Membuatsendiri.htm
just incase we could derive something out of this.....
Victor...
swez on 10/3/2006 12:01:19
Well, have read them all and frankly, these are interesting reads if one wants to fall asleep at the computer.
The main thing I have gleaned from reading so far, is at "0" volts input, a Class D amp has a duty cycle of 50%. Meaning, even when no audio signal is present, the amp is indeed drawing power of 50% of Vmax. This is just a momentary node of time, depending on the duration of time between signal inputs to be amplified.
Bottom line, I am not getting all this just yet. I think that for now, I'll just put all this aside, look at other things as time permits and see what hits me in the thickest part of the skull later... "Bonk" !!!
Swez is out to lunch until further notice on this topic.
MrBrownstone on 10/3/2006 15:03:51
Because I don't have a lot of time to proliferate nonsense.
Go to the links Victor sent. What you don't see is common sense in a lot of what is online. That's the reason I cautioned against a wikipedia-typed of site. There's more misinformation on sites valuable information. For instance.
Link1... max power 100% is 250% rms...so 40% of output is the true real world efficiency?? Already, people are saying Class Ds are 90% efficient? sure @ 100% clipped signal. And, Who drew that curve, anyway. Ever thought of actually measuring the output of a class D? Like the professionals?
Link 2... basically supports the FACT that Ds are about 75% efficient in real world terms
Do you see my point? If you don't, stop posting.
PS duty cycle is of the MUSIC..which is 10-25%. I thought we covered that 9 months ago, swez
MrBrownstone on 10/3/2006 15:13:26
The nuts and bolts of the conversation are:
a. I need an alternator for my 1000W system
b. I do not
Which is it?
b
Why? Different post
swez on 10/3/2006 16:07:14
Yeah, at the moment, this topic has pretty much run a coarse that leads me to think this answer is not easily discovered. Either the jargo and engineering-ese is the language gap or the testing modality is not well defined.
I do agree with you that music content is indeed the duty cycle and it is dynamic. (Constantly changing at all times) I am thinking the best way to do a dynamic load test, would be to rig up system, set everything to "X" watts of output and measure current and voltage on the input side of the amp as the signal modulates.
We know that voltage will remain constant as long as the ALT/BAT can keep up. Once voltage drops on the amp, we have pretty much max'd out the power supply. (ALT/BAT)
I can use dummy loads for testing as we know speakers change impedence values based on frequency. We also can calculate the current, (Ampere load) if we know Power, Resistance and/or Voltage supply. (Ohms Law derivations)
Again, I have pretty well shot the wad on this topic for now. However, your questions above... probably not needed if only 1KW's for the net load.
13.5V's x 100A's = 1350 watts at full power and whatever the duty cycle will be, it just is for short durations of time. (And no, am not going to sleep on it either) I like my sleep very much and don't wnat it disrupted by such silly notions.
swez
PS Thanks for the inputs, but a real test seems to be the best way to actually get a handle on this. In short, we have used a JL 500/1 and a 4 ohm sub at full power and that amp never broke a sweat. However, the 300/4 did get pretty warm after 15 minutes or so, when pressed hard. That says more about Class D vs Class A/B amps than anything we have discussed so far. In all, it's been a good chat.
Replies (21)
ttocs on 09/25/2006 16:06:09
it will not hurt anything. upgrading your alt also, will not hurt anything. You are not adding current or voltage to the system, just making it easier to move around which can free up a few volts....
anonymous_a on 09/25/2006 16:32:23
Thats what I thought just wanted to be extra sure though, thank you ttocs.
MrBrownstone on 09/25/2006 17:20:50
Whether or not to add an aftermarket (or upgraded) alternator has been a topic of recent debate. For the most part, unless you are competing in a DB Drag competition whereas you'll need 16V, or need 200Amps current, I just don't see the need for most daily drivers.
A fair rule of thumb should be usage and available current. I used 1400W (1kW sub amp + 400W 4ch) and the need for an alternator upgrade wasn't necessary. The car, was a 1989 Toyota Corolla...and we know how small those alternators are.
It really depends upon the type of vehicle you are using, and the power you'll be using. Remember, amplifiers only use maximum current when you are running them at maximum output...and how often is that?
swez on 09/26/2006 11:08:00
Today's vehicles are pretty complex and all the electronics used for engine, body, ABS and fuel monitoring systems, need a well regulated power supply system. If we overload them regularly with aftermarket add ons, but do not compensate for that, things can and do go south.
A case study: My Dad bought a Ford F-350 Turbo Diesel "Dually" with a HD towing. (160A, dual BATs) He had a local shop install remote start, alarm and air horns. Within a few weeks, odd things began to crop up:
1. The auto-sense headlight delay circuit failed
2. The horn relay and associated control module failed
3. A remote BAT charging circuit for the towed trailer fried out too
Each situation was related to improperly installed aftermarket add ons by some inexperienced tech, who did not know what he was doing. This shop was not able to troubleshoot the root causes. So, they disabled given features and sent the truck over to a dealership for repairs.
In all, this truck has been in the shop or off the road for several days on each issue noted above. The point here, this truck is made for HD service. However, improper install techniques on the aftermarket gadgets and gizzmos.
OK, what's the point this ol fart (swez) is trying to make here? Well, today's techs need to be VERY SKILLED and up to date on these complex vehicle packages. One cannot just slap things in w/o considering the overall effects to a factory setups.
End Rant!
Now, based on Anon's scenario, I agree with ttocs... an ALT/BAT upgrade is good insurance against premature electrical failures when using high powered audio add ons. A lot depends on the istall process and how one uses this gear later.
Yes, the Big 3 wiring upgrade allows more efficient flow of power in the electrical system. Larger wires have less resistance and can take more power than a typcial factory wiring kit. However, depending on how one installs and uses a high power audio system, this kit can easily overload the factory ALT/BAT and affect the entire electrical system.
Usually, the ALT will have abnormal power demands placed upon it and the life cycle will be much shorter than the system was originally designed for. Light dimming is a minor concern and yes, this can be reduced or eliminated with wiring upgrades in many cases.
But, if we use a stock ALT, make it run at 80-110% of its design capability on a long term basis, expect the ALT to fail, well before its time. That's the main reason we do this expensive upgrade. Basically, use the right tools for the job and all is well.
FYI: As a professional contractor for several years now, we cannot buy cheap DIY power tools. They cannot stand up to the heavy use and reliabilty factors we demand from Pro Grade tools. Yes, these tools are more expensive initially... but when your at a job site and pressing tools to their limits a lot, a field failure of a given tool is not just an inconveinece... it's a show stopper. That's lost time, productivity and may affect other contractors schedules as well. (For most GC's, that's not acceptable) But, we do carry backup tools for this very reason.
In this case, the worst scenario would be an electrical failure that leaves one stranded, (miles from home) and needing road side towing and/or repairs. That service is not cheap and we eventually wind up buying H.D. parts later anyway. So, to prevent this, we take appropriate steps to prevent such things.
swez
PS Mr. B has a good point and he probably did not abuse, (Read abnormal use) of his 89 Toyota and the gear installed. It may have worked just fine for years when using said gear at moderate demand levels. However, todays vehicles are far more complex. If we push our aftermarket systems hard for long periods of time w/o some degree of upgrades and compensations, be prepared for un-timely failures.
MrBrownstone on 09/26/2006 15:57:21
I believe that the reason your father had trouble was FORD. Electronics from the 'big 2' automakers in America are built problematic on purpose...to sell parts.
As far as my car, I hammered the hell out of that thing...for 95,000 of it's miles and didn't even need to replace alternator brushes. If your electronics fail, it's not the STEREO's fault, it's the carmaker.
Let's be real, if you are using <1000 watts, you don't need an alternator. Starting between 1kW & 2kW, there's benefit. so unless the guy is using more than 1kW, there's no need to continue this discussion.
How much power do you believe you'll be using, Anonymous?
Victor on 09/26/2006 16:48:33
alt or no alt... doesnt in actually depend on what kinda stock electricals does the amnufacturer supply.. here in india most cars have a stock alt of max 60-80 amps.. hehe.. now dont we need an alt upgrade???
anonymous_a on 09/26/2006 19:54:00
Well for now its just Rockford P6002(80 amps) Visonik amp(20 amps) Soundstorm SSL crossover(3 amps). For now the power hog is the Rockford but I may upgrade to a P8002,JBL 1200, or Infinity 1200. All three of those have three 40 amp fuses.As for now I have minimal light dimming and thought I'd take a couple of dollars and minutes to solve the problem.I do know overall a powerfull setup may shorten the alternator's life. The only reason I asked because the installer seemed so sincere about this.He acted like in order to think about "the big three" you needed to have a h.o. alternator and battery first. Then he said you didn't need to fuse the alternator to battery wire. After this little discussion got my supplies and left.Through all the websites,threads, how to's,pics,etc, I knew what the deal was but just wanted the extra input on the matter.(P.S.)How do you start a new paragraph?
swez on 09/26/2006 22:13:16
(P.S.)How do you start a new paragraph?
Use the enter button on your computer.
I believe that installer was giving a straight answer about power management issues. Here's why...
Let's say we have a give circuit in our home. It has a 14 gage wire attached to a fuse or circuit breaker in the main panel and that value is 15 amperes. Here, we are working with 120 volts AC and a current limit factor of 15 amperes. (120 x 15 = 1800 watts)
Now, suppose we grab a 6 socket plug in box and started adding devices to that plug in strip.... what will happen as we turn on these things?
1. A 150 watt light bulb: (1.25 amperes draw) AOK
2. A 1500 watt hair dryer: (11.7 A's @ high settings) Still OK
3. A 250 watt TV set: (2.1 A's) Circuit failure dude!!!
The fuse or breaker will trip out with only 3 devices as we have exceeded the current limits that line can handle. Yes, the breaker or fuse may take a few minutes to trip out, but it WILL TRIP OUT!!!
Now, in a vehicle, we also have fuses, specific wire gages for a given set of circuits and a finite amount of power in the supply feed off the ALT & BAT. The main difference here, we are dealing with low DC voltage values (12.5 - 14.4 volts DC) and "X" amount of current available from the ALT and BAT. When we add high powered add on to a stock system, sooner or later, something has to give, if we constantly demand more power from the overall system then it waas designed for right?
OK, let's take a closer look at what goes on in a car system. For example, let's start with a basic set of round numbers:
ALT: A 100 amp rated ALT will produce about 13.8 volts and up to 100A's of current at engine RPM's of 2000 or higher. At idle, this ALT can do about 50-55A's well.
Q1: What is the nominal and maximum wattage this ALT will produce at idle and >2000 RPM?
A1. 13.8 volts x 55 A's = 759 watts nominal, at engine idle speed
A1a. 13.8 volts x 100 A's = 1380 watts nominal at >2000 RPMs
Alrighty then, we now know the nominal and maximum power output capacity of this ALT. The ALT provides all electrical power to all car devices, once the engine is started. However, its first order of business, is to charge back up the BAT to a fully charged state.
A car BAT is rated at 12.5 volts DC at full charge. A typical BAT will provide 500 - 1000 Cold Cranking Amperes (CCA's) when we start the vehicle. The BAT provides adequate power to the starter and basic system components to get the engine to run properly. The more power we use to start the engine, the longer it takes the charging circuit and regulator to bring the BAT back up to full charge. (This may take ~4-10 minutes, depending on the BAT drain)
Once the engine is running smoothly, look at the charging voltage used to top off the BAT again. (Typ. 14.4 volts and as much current as is possible, to bring the BAT back up to full charge) This may take a few minutes and then, the charging circuit, (ALT and regulators) will slowly drop voltage and current demands from the ALT, as the BAT returns to normal full charged state.
FYI: When the BAT is fully charged again, voltage and current demands from the ALT are normalized and we typically see a steady voltage reading at the BAT of roughly 13.8 volts. (+/- 0.5 volts)
Got all that so far?
Anyone care to dispute this one... if so, feel free to show your lack of undertanding for all to see. hehe.. (Who's gonna bite on that hook?)
OK, now the BAT is fully charged again and the ALT goes back to cruisin' mode until we flip on a few devices like head lights, blower motor, adjust power seats, mirrors, depress the brake peddle and watch a few more lamps fire up. So far, no problems as the ALT is ready to carry these new loads. Here, the charging system now relies 100% on the ALT's power output. As we step on the gas peddle and move out, ALT power will increase as needed to keep all devices adequately powered.
Ok, now we are motoring down the road. All systems are normal and the load the ALT sees, is based on adding up power draws from all main default devices and other main circuits we need at that moment. The big wattage circuits we often use are headlights, blower motor for HVAC, side marker lamps, instrument panel displays, ECM/BCM, ABS circuits and rear window defoggers. Here, power windows, door locks, seat motors and the like, are only momentary loads. When we get them adjusted to our liking, they no longer use power.
OK, this is installment #1 on this topic for now. I will add a few more things later and continue the tuitorial as I have time. Just know we have just began this process and things get a lot more complex when we start adding AUX power devices into the mix....
Stay tuned for Part II,
Swez
PS For Annon, use the enter bar on your keyboard to start a new paragraph OK... Thanks bro... SMILE
swez on 09/29/2006 10:18:26
Part II, the BATTERY as a helper.
OK, we have discussed the function of the Alternator. Now, let's look at the Battery aspects of a given system.
The BAT is a power storage device. When fully charged, we see about 12.5 volt DC power source. As for current capacities, this is variable based on the size of the battery, # of plates used, thickness of storage plates and the type of electrolyte used.
The most common car battery is a wet cell, lead-acid battery. We are now seeing a steady influx of new battery technologies that employ gelled electrolytes, (Gel Cells) and some hybrids that use a combination of wet and gel cell technologies.
Anyway, back to the basics... a lead-acid battery consists of many thin plates, grouped together in multi-celled chambers. They are rated in Ampere hours and the larger the battery package is, the more Ampere hours they can deliver.
The general functions of a car battery are:
1. Starting the engine
2. Powering electronic devices w/o the engine running (short term)
3. A power storage reserve
When we jump into the car and turn the key to start the car, the battery takes a pretty large hit of surge drain as the starter engages and cranks the engine over. In a small engine, (2.0 Liters or less) this surge may be as little as 100 -150 amperes of current surge in a 5-10 second period. For a large V-6 or V-8 engine, that surge might be as high as + 300 amperes for a short duration. That's why we see tiny batteries in very small engines and large battery packs in larger engines.
Once the engine starts, the Alternator takes over and begins to recharge the depleted battery and power the rest of the vehicles' needs. This recharging state will last as long as the battery is below rated voltage and demanding power to refill itself to a balanced condition. Here, the voltage regulator in the charging circuit will allow higher voltages from the Alt to flow to the Bat and other electrical components as needed. This high voltage condition, (~14.4 volts) will remain as long as the Bat is recharging.
When the Bat is adequately charged, the regulator circuits sense the system is now back to normal and the Alt will return to normal operating conditions of between 13.5 - 13.8 volts and deliver as much current as needed to feed all active circuits. Are we tracking together so far?
**************************************************************************
Now, suppose we added a few large power devices, (Amplifiers,Aux lighting, CB radio Kickers, etc.) a given factory electrical system. How do those devices play out their roles in a given scenario?
Well, when not in use, these devices do nothing and don't affect the system at all. However, when we activate them and dial up the power demands on the electrical system at large, they draw watts from the system as needed and can become substantial loads on a given stock electrical system. Depending on how much power we demand them to generate, this determines how large the load will be on the charging system.
A modest audio system of say 300 watts, will not put any major strain on the electrical system. At full output power, the electrical system can easily manage this type of load. Depending on the amp technology used, (Class D sub or Class A/B designs) we are looking at a range of current draw between 25 - 35 amperes of current draw. Here, let's assume the worst case scenario, the amplifier is at full power and using high duty cycle test tones. The amp is working hard, but the electrical draw from the system is modest and easily managed. So far, so good huh?
**************************************************************************
Now, let's change the scenario and add a few potent amplifiers. This changes the game considerably. As an example, let's say we have a 500 watt Class D amp for the sub(s) and a 300 watt amp (75 x 4) for mid/highs. How will this combination of amps affect the electrical system? Depending on how we use them, it could be minimal or the affect can be substantial. The scenario:
1. Class D amp, 500 RMS (~80% efficiency rating)
2. Class A/B amp, 300 RMS (~60% efficiency rating)
The worst case scenario is that we are using high duty cycle test tones as the audio content. Let's say we are dialing in the amps for maximum RMS output and putting the system to its biggest test. Basically, we are pushing the audio system to maximum performance and as such, the amps are working at full capacity. What's the electrical load we can expect under these conditions?
A. The 500 RMS sub amp is pretty efficient (80% eff) and will draw "X" amount of watts under full load test conditions. Here are the numbers
we can anticipate under test conditions:
500/.80 (eff) = 625 watts
625 watts / 13.5 (ref supply voltage) = 46.3 amperes
Pretty strong current pull huh? You bet... and the stock electrical system is going to work pretty hard to manage that load too.
B. The 75 x 4, Class A/B amp delivers about 300 watts RMS at full power. How much power does it consume?
300/.60 (eff) = 500 watts
500/13.5 (ref supply voltage) = 37.0 amperes
Now, add them up... 46.3 + 37.0 = 83.3 amperes total
Hummm, that's about 1125 watts consumed to produce 800 watts of audio output power. That's enough wattage draw to run a 1.5 HP DC electric motor. (746 watts = a 1.0 Horse Power load) Whoa.... now we are talking some serious power consumption here right?
**************************************************************************
As we can plainly see, this type of rig is capable of consuming considerable current from a meager factory supply system. How does a 100A ALT and a typical 600 CCA BAT handle such an adverse load?
I will stop here for now and pick up on the subject later. Digest this information, mull it over and THINK about what all this means in broad terms. The goal here, is to make one think about how large power amps can affect the stock electrical system of any given vehicle.
Happy reading,
swez
MrBrownstone on 09/29/2006 22:20:52
I agree with Victor...earlier...
"alt or no alt... doesnt in actually depend on what kinda stock electricals does the amnufacturer supply.. here in india most cars have a stock alt of max 60-80 amps.. hehe.. now dont we need an alt upgrade???"
If your lights dim, and it bothers you, get a capacitor ( or several). There isn't a lot of science indicating that you'll hear any difference, but at least the amount of dimming will either be reduced or go away. An upgraded alternator will also provide more current, but you need to make certain that the upgraded alternator puts out more at idle...not at higher RPMs or it won't make much difference.
What happens is when your accessories (car audio included) use more current than the alternator can provide, voltage drops. This is why the lights dim. As soon as the load eases, the lights come right back.
Unless your lights dim, and do NOT return to brightness, you don't need an alternator upgrade. You may DESIRE one if you intend to enter a car audio competition, but for daily driving, It's just not necessary.
On a side note: the system you are talking about is so small I doubt that there's enough current draw worth arguing about. Get me to 2kW output, then we're talking. Get me to 3kW, or a competition system such as DB DRAG, then an alternator is needed.
swez on 09/30/2006 01:24:37
Well, 2 KWatts are a lot off juice to ask of a stock system if doing more than a few seconds of "burp tones". If a 100A Alt can deliver 14.4 volts. That's 1440 watts or 1.44 KW continous so far.
A 2 KW Class D (80% eff) will draw about 2.5 KW at full power w/o clipping. If we allow for 10% clipping or more, that KW draw # is even larger for the duration of the burp. This tells me the BAT (or several Bat's will) have to make up the difference. A Bat can deliver a 300A burst for some duration of time. (300 x 12.5 = 3.75 KW) The question in my head is... How long can a system take that kind of load and how long does it take to recharge a BAT after such a hit?
Yeah, I may be barking up a dead tree here... but allow me an opportunity to figure this out. I am willing to make a few mistakes and learn something here. Learning new ideas (or old lessons that others have already mastered) often requires a few broken yokes. In any event, the yokes on my face and since I am a grown man, I can wipe it off if that point comes along later.
I agree about the light dimming part... no problems with that. As you say, it's just a momentary lag in voltage drop as the amp draws this spiked amount of power from the charging system. I get that well enough.
However, noone run their lights in a Burp/Fart tone test right? That's just raw power off the ALT and BAT(s) combined. But what about a daily driver that's pushing 2KW's of amping power and also serving up other loads that add another 0.75 KW.
To my present reckoning, a few hours of commuting with all this going on, is a pretty tall order to fill. Something has to give, sooner or later right? What's missing in this scenario? Or, what erronous assumptions am I over looking here? That is what is pickling me???
swez
PS Yes, I am trying to deceifer a strange code here. "it just works that way" is not the only answer I am looking for. (Or is that the point I fail to see???) Puzzled in Detroit...
PSS Besides, The Tiger's lost to KC Royals tonight and now, they have to slug it out in the numbers game with the Twins and them damn Yankees for a chance at the Central Divison pennant and a wild card slot for the World Series. Who cares right? Least of all... me! But Deee-troit needs some good news this year and the Tiger's have a long shot at it. So, with baited breath, we wait some more. hehe
MrBrownstone on 10/2/2006 00:04:46
Well, in the above example, noone is using 2kW and noone is using continuous power at 100% RMS!!! When we get to 2kW, more to talk about. At this juncture, there's just nothing to talk about.
Your current calculations are assuming that the electrical system and the amplifier are like a firehose. They are not, more like a sprinkler with 3/4 second pauses. 3/4 of each second, the output on your amplifier is resting...catching up....otherwise, the car would stop running or the amp would shut off.
swez on 10/2/2006 08:56:03
Was thinking more along the lines of a variable load model too. Like your analogy of a fire hose, but VS a pulse type sprinkler system.
Are you sure noone listens to their systems at high power all the time? Judging from what I see/hear in this hood, I beg to differ. I live ~1/4 mile from our local High School. I know when they get out of school 'cause I can hear them from at least 2 blocks away.
Same thing at stoplights, gas stations and the 7/11's. These idiots charge up and down the residential area like they are the only peeps in town. They leave their rigs on and boomin' while getting gas and charging up their 64 oz Slurppies.
I have been tempted to ask them to show me thier gear at times... then when they do, I'd reach in and yank the livin' crap on the power leads to thier amps. Then, for insurance, I'd short that sucker to the amp casing and put them out of biz for a long time. Imagine that... arch welding the power cable to the amp casing... hummm, wonder how that would work out huh?
In short, some guys have no clue how irritating their behavior is to others who don't like "C-RAP" music.
Ahhhh, I feel better now. Thanks for letting me vent!!! END RANT
swez COFFEE
MrBrownstone on 10/2/2006 16:45:02
hee Hee....C-RAP. A swez original from 1988. :-)
Listening to your system at 100% or 100%?
100% loudness, yes
100% of amplifier's capabilities...NO
There's just no way you could tolerate the total 100% distortion all the time. 115% of RMS rating, sure..but distortion would be so highly audible...and undesireable that I doubt it.
Even then, we're not talking 100% of the amplfier's usage, and when we are...we're talking for 1/4 of real time. That gives our alternator 3/4 of a second to reload.
Think of it as a TV weather radar. They broadcast 250,000 W to 1MW of power...but if they did it continuously, there's be melted birds allover the countryside withing a 100 foot area.
Divide your current load numbers by 4...because that's what the alternator sees. At 100% clipped signal (250% RMS power) yes, it's seeing 100%
END terminology parsing.
Victor on 10/2/2006 17:22:37
dunno whats up with dave.. but he sure is writing a lot these days..forget paragraphs... he's writing essays.... and this particular alternator thingy has really churned up something inside him...
swez on 10/2/2006 19:37:51
Yes, I am trying to get something out of this whole issue. The part I am struggling with is the thought that amps work on a 25% duty cycle.
Have heard that statement many times form Mr. B and I'd like to see it from another reputable source. If I read it in a trade magazine and it had Dave Navone or Richard Clark's name on it, I'd buy it, sell it and just shut up already.
Liked your Microwave analogy there B. There is talk of developing solar power stations in a geo-sync orbit. They are thinking about many large solar cell arrays up in space, coupled with a microwave transmitter to beam energy back to a target on earth. The trick is the beam diameter to use.
A narrow and coherant beam is too intense and concentrated for safe use. However, if the beam were several meters in diameter, the energy per cubic meter would be safe for planes, people, wildlife and such, not to get vaporized. Cool idea huh? Sure, they could do a hard wire drop too... but many miles of power cable are expensive, dangerous and cannot support its own weight.
B... Just show me where I can find out more about Duty Cycles on audio amplification factors. If that is possible and I can understand it... I'll shut up and go back to sleep.... Whaaaaah GRIN
Swez
Victor on 10/3/2006 02:14:04
http://www.maxim-ic.com/appnotes.cfm/appnote_number/1760
http://sound.westhost.com/articles/pwm.htm
http://members.tripod.com/valveaudio/Membuatsendiri.htm
just incase we could derive something out of this.....
Victor...
swez on 10/3/2006 12:01:19
Well, have read them all and frankly, these are interesting reads if one wants to fall asleep at the computer.
The main thing I have gleaned from reading so far, is at "0" volts input, a Class D amp has a duty cycle of 50%. Meaning, even when no audio signal is present, the amp is indeed drawing power of 50% of Vmax. This is just a momentary node of time, depending on the duration of time between signal inputs to be amplified.
Bottom line, I am not getting all this just yet. I think that for now, I'll just put all this aside, look at other things as time permits and see what hits me in the thickest part of the skull later... "Bonk" !!!
Swez is out to lunch until further notice on this topic.
MrBrownstone on 10/3/2006 15:03:51
Because I don't have a lot of time to proliferate nonsense.
Go to the links Victor sent. What you don't see is common sense in a lot of what is online. That's the reason I cautioned against a wikipedia-typed of site. There's more misinformation on sites valuable information. For instance.
Link1... max power 100% is 250% rms...so 40% of output is the true real world efficiency?? Already, people are saying Class Ds are 90% efficient? sure @ 100% clipped signal. And, Who drew that curve, anyway. Ever thought of actually measuring the output of a class D? Like the professionals?
Link 2... basically supports the FACT that Ds are about 75% efficient in real world terms
Do you see my point? If you don't, stop posting.
PS duty cycle is of the MUSIC..which is 10-25%. I thought we covered that 9 months ago, swez
MrBrownstone on 10/3/2006 15:13:26
The nuts and bolts of the conversation are:
a. I need an alternator for my 1000W system
b. I do not
Which is it?
b
Why? Different post
swez on 10/3/2006 16:07:14
Yeah, at the moment, this topic has pretty much run a coarse that leads me to think this answer is not easily discovered. Either the jargo and engineering-ese is the language gap or the testing modality is not well defined.
I do agree with you that music content is indeed the duty cycle and it is dynamic. (Constantly changing at all times) I am thinking the best way to do a dynamic load test, would be to rig up system, set everything to "X" watts of output and measure current and voltage on the input side of the amp as the signal modulates.
We know that voltage will remain constant as long as the ALT/BAT can keep up. Once voltage drops on the amp, we have pretty much max'd out the power supply. (ALT/BAT)
I can use dummy loads for testing as we know speakers change impedence values based on frequency. We also can calculate the current, (Ampere load) if we know Power, Resistance and/or Voltage supply. (Ohms Law derivations)
Again, I have pretty well shot the wad on this topic for now. However, your questions above... probably not needed if only 1KW's for the net load.
13.5V's x 100A's = 1350 watts at full power and whatever the duty cycle will be, it just is for short durations of time. (And no, am not going to sleep on it either) I like my sleep very much and don't wnat it disrupted by such silly notions.
swez
PS Thanks for the inputs, but a real test seems to be the best way to actually get a handle on this. In short, we have used a JL 500/1 and a 4 ohm sub at full power and that amp never broke a sweat. However, the 300/4 did get pretty warm after 15 minutes or so, when pressed hard. That says more about Class D vs Class A/B amps than anything we have discussed so far. In all, it's been a good chat.
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