Question regarding sound quality from a sub amp.
Here is the dillemma: I would like to upgrade my subwoofer, and amp. I've done the looking and have pretty much settled on a JBL GTO 12". It is available in 2 configurations, SVC (4ohms) or DVC (4 ohms each, likely to wired into a 2 ohm parallel load). RMS rating for either config is 300W (150 per coil on the DVC). The rest of my speakers are JBL and I'm happy with them, so I figured I'd stay within the brand for the sub.
The question is, if I'm looking for sound quality, would I be better off going with a mono class D sub amp between 300 - 350 W RMS into a 2 ohm load, or bridging two channels of a class A/B into a single 4 ohm load to net approximately the same power? It has always been my understanding that class D amps are more efficient, but don't run as clean as A/B. Keep in mind that available current is not an issue (my truck came with a towing package that rarely gets used that includes a 140amp alternator and a heavy duty battery). Assume also that whatever amp I go with will be of a sufficiently good quality as to eliminate inflated power ratings (yeah, I know how to read between the lines on power specs).
I'm a noob on the forum But have lurked and checked out info. You folks seem like adults here, as opposed to the adolescents on some of the other forums. I'd appreciate some insight, thanks.
Replies (9)
Victor on 01/20/2006 01:53:39
You are right, the A/B are much cleaner, but when it comes to bass frequencies you really wont notice much difference, also lower frequencies need more power to be heard at the same level. So when it comes to amplification of lower frequencies what matters is the efficiency of the amp.
A Class D topology is usually preffered to power subwoofers.
Your best option here wud be ( if u wanna stay with JBL )
the GTO 301.1 or the alpine MRD -M 301.
Victor....
jazzbass on 01/20/2006 03:27:07
Actually, you read my mind, these are two of the amps that I had looked at. I was also considering a Soundstream Tarantula series 340.2 with a bridged rms of 340 W. I'm leaning in the direction of the JBL though...
Victor on 01/20/2006 04:53:02
That is a solid amp , the soundstream Tarantula is definitely a good one, but even tho you got a batt and alt upgrade i would suggest you still go for a class D instead of a A/B 2ch and bridge. ( by the way there are some class A/B monobloks too, I have seen a couple from blau )
About that JBL 301.1 , JBL has no where mentioned its class D topology for that amp, that amplifiers Max current draw is 40amps and the rms output is 294 @14.4volts @ 2 ohms, if we calculate its efficiency with these parameters it comes upto 52% which makes me lean towards the thought that this JBL amp is a class A/B monoblock. Cause Class D are anywhere higher then 70% efficiency.
tho the 601 and the 1201 the bigger bros of the 301 are clearly mentioned as Class D monoblocks.
Also the Alpine is much stronger in terms of specs when compared to the JBL, and a pure class D topology too.
There are many class D' amplifiers out in the market that could satisfy your needs.
If you could give us an idea what amps u got in mind we cud tell u the pro's and con's as well as our experiences with them, We got many installers and tech pro's on CK i doubt if there a famous brand which someone on CK has not worked with..
Victor...
swez on 01/20/2006 06:10:49
Most Class D amps of any repute, have low distortion numbers. (Typically 1% or less, at rated power) Since we cannot detect distortion levels below ~3%, the point is moot.
For HI-FI quality mids/highs, we do want a clean Class A/B or "T" class amplifier. Here, it's not uncommon to see THD #'s in the 0.0X %range or better. That's all good as well. But again, the human ear cannot detect THD's until ~2-3% in that freq range. (well above 500 Hz)
Swez
jazzbass on 01/20/2006 07:41:43
Actually very happy with my current amp for mid/high stuff. I'm using a US Acoustics USB 4065 to drive the rest of the set up. The only weak link has been the sub/amp portion (which I sort of knew would be the case at the time but the budget was getting thin...) I was happy to see the company on the "recommended" portion of the list.
swez on 01/20/2006 13:52:23
Yep, Alpine, JBL, Infinity, Kicker and many others are very good products that won't take a huge bite out of the wallet.
Have a US Acoustics USA-4060 too. It's the older one that came before the USX and USB series. Nice little amp, a friend gave it to me for doing one of his custom fit subs. Also have a 300 watt JBL amp for the subs. (Sound Stream SPL 10's) Some might say it's hodge podge, but it's the speakers and install process that makes the real pudding.
Yeah, would love a matched set of JBL amps. (GTO 600.1II, GTO 75.4II) But hey, that's about $650.00. That's rent for a month or 1/2 a house note. So, being the fruggle guy, guess I'll just leave things at that.
Swez
Ash on 01/20/2006 17:28:45
Got the USB 4065 too. Can't beat it for the clean power and size package. Like Swez, I ran it with a JBL 300.1 and it was almost the perfect combo. I just didn't like the non-defeatable x-over on the JBL. I wanted to use the USB's preout x-over (24db octave lpf). 300 watts rms is a perfect sub compliment to the USB 4065 no matter what amp as long as it is true output.
jazzbass on 01/20/2006 17:50:52
Cool, sounds like the way to go. Ash, I know what you mean, the problem with the pre outs on the USB is that you cant get them to go full range unless one of your channel sets is running full range. I high pass everything into the interior speakers (nobody likes the smell of roasted voice coil). This leaves the low pass outputs, going into another low pass cross over in the class D. Isn't that a little like "crossing the streams"?
No biggie, I'll just route the pre-out signals differently from the head, and all will be good.
Ash on 01/20/2006 18:01:34
I tried it with both low pass on both amps it just made it harder to tune. I ended up feeding both amps from the HU with the USB's input feed split to both front and rear. Not bad, just couldn't fade the rear mids with the HU.
Still, it was/is a heckuva combo.
Here is the dillemma: I would like to upgrade my subwoofer, and amp. I've done the looking and have pretty much settled on a JBL GTO 12". It is available in 2 configurations, SVC (4ohms) or DVC (4 ohms each, likely to wired into a 2 ohm parallel load). RMS rating for either config is 300W (150 per coil on the DVC). The rest of my speakers are JBL and I'm happy with them, so I figured I'd stay within the brand for the sub.
The question is, if I'm looking for sound quality, would I be better off going with a mono class D sub amp between 300 - 350 W RMS into a 2 ohm load, or bridging two channels of a class A/B into a single 4 ohm load to net approximately the same power? It has always been my understanding that class D amps are more efficient, but don't run as clean as A/B. Keep in mind that available current is not an issue (my truck came with a towing package that rarely gets used that includes a 140amp alternator and a heavy duty battery). Assume also that whatever amp I go with will be of a sufficiently good quality as to eliminate inflated power ratings (yeah, I know how to read between the lines on power specs).
I'm a noob on the forum But have lurked and checked out info. You folks seem like adults here, as opposed to the adolescents on some of the other forums. I'd appreciate some insight, thanks.
Replies (9)
Victor on 01/20/2006 01:53:39
You are right, the A/B are much cleaner, but when it comes to bass frequencies you really wont notice much difference, also lower frequencies need more power to be heard at the same level. So when it comes to amplification of lower frequencies what matters is the efficiency of the amp.
A Class D topology is usually preffered to power subwoofers.
Your best option here wud be ( if u wanna stay with JBL )
the GTO 301.1 or the alpine MRD -M 301.
Victor....
jazzbass on 01/20/2006 03:27:07
Actually, you read my mind, these are two of the amps that I had looked at. I was also considering a Soundstream Tarantula series 340.2 with a bridged rms of 340 W. I'm leaning in the direction of the JBL though...
Victor on 01/20/2006 04:53:02
That is a solid amp , the soundstream Tarantula is definitely a good one, but even tho you got a batt and alt upgrade i would suggest you still go for a class D instead of a A/B 2ch and bridge. ( by the way there are some class A/B monobloks too, I have seen a couple from blau )
About that JBL 301.1 , JBL has no where mentioned its class D topology for that amp, that amplifiers Max current draw is 40amps and the rms output is 294 @14.4volts @ 2 ohms, if we calculate its efficiency with these parameters it comes upto 52% which makes me lean towards the thought that this JBL amp is a class A/B monoblock. Cause Class D are anywhere higher then 70% efficiency.
tho the 601 and the 1201 the bigger bros of the 301 are clearly mentioned as Class D monoblocks.
Also the Alpine is much stronger in terms of specs when compared to the JBL, and a pure class D topology too.
There are many class D' amplifiers out in the market that could satisfy your needs.
If you could give us an idea what amps u got in mind we cud tell u the pro's and con's as well as our experiences with them, We got many installers and tech pro's on CK i doubt if there a famous brand which someone on CK has not worked with..
Victor...
swez on 01/20/2006 06:10:49
Most Class D amps of any repute, have low distortion numbers. (Typically 1% or less, at rated power) Since we cannot detect distortion levels below ~3%, the point is moot.
For HI-FI quality mids/highs, we do want a clean Class A/B or "T" class amplifier. Here, it's not uncommon to see THD #'s in the 0.0X %range or better. That's all good as well. But again, the human ear cannot detect THD's until ~2-3% in that freq range. (well above 500 Hz)
Swez
jazzbass on 01/20/2006 07:41:43
Actually very happy with my current amp for mid/high stuff. I'm using a US Acoustics USB 4065 to drive the rest of the set up. The only weak link has been the sub/amp portion (which I sort of knew would be the case at the time but the budget was getting thin...) I was happy to see the company on the "recommended" portion of the list.
swez on 01/20/2006 13:52:23
Yep, Alpine, JBL, Infinity, Kicker and many others are very good products that won't take a huge bite out of the wallet.
Have a US Acoustics USA-4060 too. It's the older one that came before the USX and USB series. Nice little amp, a friend gave it to me for doing one of his custom fit subs. Also have a 300 watt JBL amp for the subs. (Sound Stream SPL 10's) Some might say it's hodge podge, but it's the speakers and install process that makes the real pudding.
Yeah, would love a matched set of JBL amps. (GTO 600.1II, GTO 75.4II) But hey, that's about $650.00. That's rent for a month or 1/2 a house note. So, being the fruggle guy, guess I'll just leave things at that.
Swez
Ash on 01/20/2006 17:28:45
Got the USB 4065 too. Can't beat it for the clean power and size package. Like Swez, I ran it with a JBL 300.1 and it was almost the perfect combo. I just didn't like the non-defeatable x-over on the JBL. I wanted to use the USB's preout x-over (24db octave lpf). 300 watts rms is a perfect sub compliment to the USB 4065 no matter what amp as long as it is true output.
jazzbass on 01/20/2006 17:50:52
Cool, sounds like the way to go. Ash, I know what you mean, the problem with the pre outs on the USB is that you cant get them to go full range unless one of your channel sets is running full range. I high pass everything into the interior speakers (nobody likes the smell of roasted voice coil). This leaves the low pass outputs, going into another low pass cross over in the class D. Isn't that a little like "crossing the streams"?
No biggie, I'll just route the pre-out signals differently from the head, and all will be good.
Ash on 01/20/2006 18:01:34
I tried it with both low pass on both amps it just made it harder to tune. I ended up feeding both amps from the HU with the USB's input feed split to both front and rear. Not bad, just couldn't fade the rear mids with the HU.
Still, it was/is a heckuva combo.
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