Im running three MTX Amps. First a 6304 a 4-channel amp routed to 4 5x7's and 2-6.5's and tweets. second- 6500D pushin 2 MTX 8k tens in a custom ported box. last a 4250D to a single MTX 8k ten in a band pass. problem is the largest alternator available at the local autoparts store is 70 amps (94 Nissan Pathfinder) the 6304 and 6500D both are pullin 75 amp each and the 4250 is pullin 50 amps. I have a 1 farad capacitor as well as a .5 farad capacitor. and a dist. block to fit in somewhere in the mix. The digital read out on the cap hovers around 10-11 amps with car running. I am using a 4 guage power lead, should I step up? secondary batt.? According to MTX's certification papers The 6304 is running @112wattsx4, 6500D 623watts per ch., 4250D @212watts rms with applicable ohmage.
Replies (6)
Swez on 09/29/2003 09:20:10
Bet you have a severe voltage drop problem here huh? The cap measures voltage, not current... so if you are getting those numbers on the display.... it's a wonder the vehicle even operates properly with all the amps running.
This proves what we have been saying for a long time... CAPS DO NOT SOLVE CHRONIC POWER SHORTAGES !!!
OK, let's look at your options:
1. Get the largest CCA rated battery your truck can handle (1000 CCA)
2. Upgrade your main power feed wire to amps with #0 or #2 gage and same for ground... #4 will not cut it
3. Change wires from ALT/BAT and BAT/GND to #4 min.
4. If these tricks cannot get the digital readout back up above 12.5 volts, you are looking at a new HO ALT as well
A custom ALT rebuilder may be able to tweak your present ALT to get closer to 100A. That is a cheap way to get more power if they can use the same casing. If not, you'll have to consider either getting a HO ALT from Ohio Generator or Stinger or consider installing a secondary ALT/BAT dedicated to powering only your audio gear. This mat be tricky to do... but others have resorted to custom hardware adaptors, pully and belts to get this to work.
Comments?
Swez
phatony on 09/30/2003 01:16:57
I have consulted a few so called "experts" and all have assured me that 4 guage would be sufficient. I personnally did not agree, when in doubt, why not step it up. I have built a dozen or so systems, for myself, and friends. So far this is the largest yet. I have never gotten a straight answer for it, but at what point do you step up. I plan on stepping up the wire and upgrading my batt. and I believe that will make a signaficant differance. Another item I have recieved mixed opinions for, is how to run my dist. block and caps. right now I have my battery lead to 1 farad cap. cap to dist block. from dist. block-- 2- 4 guage wires / inline fuses to my D amps then an 8 guage to a .5 farad cap then to my 4 ch. amp Is there a better way? My logic was to prevent the bass from drawing from the highs. Any tips?
phatony on 09/30/2003 01:41:26
also want to add that I only recieve those low voltage readings on the cap at the most extreme bass hits, at my max volume setting, for only a split second at a time. Is that a result of my undersized wire? That is what I am thinking.
Swez on 09/30/2003 08:28:22
Part of it is the wire, the balance of the issue is insufficient power (current) to power the big amps you are using.
The Caps are generally intended for sub amps and not much of a benefit to mid/highs amps which draw less current when crossovers (HPF) are set correctly. (~80 Hz and up for mids and highs)
That #4 gage wire can current demands of 80 -100 amps in short burst. But the length of the wire and hense, its resistance go up with length and heat. The heat can be generated by trying to pull large amount of current through too small a diameter wire. Check this your self by touching the jackets at battery and amps, after the system has been running hard for say 10-15 minutes. If the wire feels warm, too much current for that wire.
For now, would you consider saving yourself a major repair bill by disconnecting the amp that power the BP sub? Looks like total max current demand is ~190A when the system is fully powered up. But in real application. That number is actually closer to 125A. That leaves your system 75A short just to power all your ausio gear.
Your vehicle needs about 40-60A's to run properly. The rest is for extra componets that are not in use all the time... Rear window defogger, high beams, fog lights and such.
In short, either cut back on the current draw for now or face alternator meltdown in short order.
Swez
phatony on 10/1/2003 00:19:53
On that note... would it be possible to run all my subs off the 6500D while maintaining a 2 ohm load. Or would the combo of two ported and the bp conflict. The ported boxes are independant of each other.
Swez on 10/1/2003 08:16:20
The 8000 subs comes in 4 & 8 ohm SVC's. You have 3 of them in all yes? If you wired all 3 (assuming 4 ohm subs) in parallel to the amp, the amp will see ~1.33 ohms. This amp is rated for 2 ohm load operation and if you tried to run it lower, it may take it... but cooling the amp to keep it operational would be manditory.
Also, the power to each sub would be reduced from ~250 RMS per sub (2 subs) to ~166 watts RMS per sub. Workable... but not pushing the subs to full potential either.
Now, if these subs were actually 8 ohm subs, wiring all in parallel will work on this amp as the net load will be 2.66 ohms. The amp can manage that load, but still... your power per sub will be a tad over 150 watts RMS per sub. That will work, just not getting anywhere near the full SPL from the subs is all. These are rated at what... 400 watts RMS per sub?
The only real options I can see here are:
1. Drop to 1 sub box (2x10 ported and the 6500D) ~40A max current draw
2. Use the BP sub and the 6500D, but dial back on the gain a tad to prevent damage to sub
3. Consider a more efficient sub design, ran off the 6500D
The 8000 series 10's are very inefficient. (83.4 dB @ 1 watt) If you wanted to use a more efficient sub (say 88-90 dB@ 1 watt) and have a 2 ohm load, this would be a good way to get the most from a single amp and sub. However, there may still be power issues to deal with.
Can you see yourself selling the all MTX subs and boxes and going with a more efficient 2x12 or 1x15 ported design? This could net more SPL, less current draw than your present system and a single enclosure to lug around?
The only other option I can see, is to upgrade the ALT/BAT & wiring to the largest current output you can find and keep what you have now. It is possible to add a 2nd battery in the rear for your amps only and use a battery isolation charging device... but these have drawbacks as well.
Comments?
Swez
Replies (6)
Swez on 09/29/2003 09:20:10
Bet you have a severe voltage drop problem here huh? The cap measures voltage, not current... so if you are getting those numbers on the display.... it's a wonder the vehicle even operates properly with all the amps running.
This proves what we have been saying for a long time... CAPS DO NOT SOLVE CHRONIC POWER SHORTAGES !!!
OK, let's look at your options:
1. Get the largest CCA rated battery your truck can handle (1000 CCA)
2. Upgrade your main power feed wire to amps with #0 or #2 gage and same for ground... #4 will not cut it
3. Change wires from ALT/BAT and BAT/GND to #4 min.
4. If these tricks cannot get the digital readout back up above 12.5 volts, you are looking at a new HO ALT as well
A custom ALT rebuilder may be able to tweak your present ALT to get closer to 100A. That is a cheap way to get more power if they can use the same casing. If not, you'll have to consider either getting a HO ALT from Ohio Generator or Stinger or consider installing a secondary ALT/BAT dedicated to powering only your audio gear. This mat be tricky to do... but others have resorted to custom hardware adaptors, pully and belts to get this to work.
Comments?
Swez
phatony on 09/30/2003 01:16:57
I have consulted a few so called "experts" and all have assured me that 4 guage would be sufficient. I personnally did not agree, when in doubt, why not step it up. I have built a dozen or so systems, for myself, and friends. So far this is the largest yet. I have never gotten a straight answer for it, but at what point do you step up. I plan on stepping up the wire and upgrading my batt. and I believe that will make a signaficant differance. Another item I have recieved mixed opinions for, is how to run my dist. block and caps. right now I have my battery lead to 1 farad cap. cap to dist block. from dist. block-- 2- 4 guage wires / inline fuses to my D amps then an 8 guage to a .5 farad cap then to my 4 ch. amp Is there a better way? My logic was to prevent the bass from drawing from the highs. Any tips?
phatony on 09/30/2003 01:41:26
also want to add that I only recieve those low voltage readings on the cap at the most extreme bass hits, at my max volume setting, for only a split second at a time. Is that a result of my undersized wire? That is what I am thinking.
Swez on 09/30/2003 08:28:22
Part of it is the wire, the balance of the issue is insufficient power (current) to power the big amps you are using.
The Caps are generally intended for sub amps and not much of a benefit to mid/highs amps which draw less current when crossovers (HPF) are set correctly. (~80 Hz and up for mids and highs)
That #4 gage wire can current demands of 80 -100 amps in short burst. But the length of the wire and hense, its resistance go up with length and heat. The heat can be generated by trying to pull large amount of current through too small a diameter wire. Check this your self by touching the jackets at battery and amps, after the system has been running hard for say 10-15 minutes. If the wire feels warm, too much current for that wire.
For now, would you consider saving yourself a major repair bill by disconnecting the amp that power the BP sub? Looks like total max current demand is ~190A when the system is fully powered up. But in real application. That number is actually closer to 125A. That leaves your system 75A short just to power all your ausio gear.
Your vehicle needs about 40-60A's to run properly. The rest is for extra componets that are not in use all the time... Rear window defogger, high beams, fog lights and such.
In short, either cut back on the current draw for now or face alternator meltdown in short order.
Swez
phatony on 10/1/2003 00:19:53
On that note... would it be possible to run all my subs off the 6500D while maintaining a 2 ohm load. Or would the combo of two ported and the bp conflict. The ported boxes are independant of each other.
Swez on 10/1/2003 08:16:20
The 8000 subs comes in 4 & 8 ohm SVC's. You have 3 of them in all yes? If you wired all 3 (assuming 4 ohm subs) in parallel to the amp, the amp will see ~1.33 ohms. This amp is rated for 2 ohm load operation and if you tried to run it lower, it may take it... but cooling the amp to keep it operational would be manditory.
Also, the power to each sub would be reduced from ~250 RMS per sub (2 subs) to ~166 watts RMS per sub. Workable... but not pushing the subs to full potential either.
Now, if these subs were actually 8 ohm subs, wiring all in parallel will work on this amp as the net load will be 2.66 ohms. The amp can manage that load, but still... your power per sub will be a tad over 150 watts RMS per sub. That will work, just not getting anywhere near the full SPL from the subs is all. These are rated at what... 400 watts RMS per sub?
The only real options I can see here are:
1. Drop to 1 sub box (2x10 ported and the 6500D) ~40A max current draw
2. Use the BP sub and the 6500D, but dial back on the gain a tad to prevent damage to sub
3. Consider a more efficient sub design, ran off the 6500D
The 8000 series 10's are very inefficient. (83.4 dB @ 1 watt) If you wanted to use a more efficient sub (say 88-90 dB@ 1 watt) and have a 2 ohm load, this would be a good way to get the most from a single amp and sub. However, there may still be power issues to deal with.
Can you see yourself selling the all MTX subs and boxes and going with a more efficient 2x12 or 1x15 ported design? This could net more SPL, less current draw than your present system and a single enclosure to lug around?
The only other option I can see, is to upgrade the ALT/BAT & wiring to the largest current output you can find and keep what you have now. It is possible to add a 2nd battery in the rear for your amps only and use a battery isolation charging device... but these have drawbacks as well.
Comments?
Swez
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