# Question on getting enough power...SounDigital 5500.1D Power series



## wolfrogers (5 mo ago)

So I'm running a 15" Crossfire XS and a Fi Team 12 off of this SounDigital 5500.1D Power Series amp. I just repaired it because all the mosfets on the power supply side popped their legs off. I was told by a SounDigital guru that it was most likely because of a lack of power supplying the amp. I've got a second 140 amp alternator running on a seperate circuit from the rest of the truck. This alternator dumps juice to 4 batteries that are less than a foot from the amp...it powers nothing else. Would a large capacitor help to keep the amp fed a little better, or am I going to have to bite the bullet and buy a high output alternator to prevent the amp blowing out again?


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## daloudin (Nov 2, 2020)

Lots of questions...
Two different sized subs from two different manufacturers?
Are they both Dual 4 Ohm Subs?
Enclosure alignments?
What size and type batteries?
What kind/size of wire are you using for Charging and also from Amp to Subs?

Obviously a 500-1,000 Farad Cap Bank would be optimal but if you have the right kind of batteries then that should be sufficient, but the larger Alternator question is a function of the Amp/Hour capacity of your batteries and how much voltage drop you are seeing during runs.


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## wolfrogers (5 mo ago)

daloudin said:


> Lots of questions...
> Two different sized subs from two different manufacturers?
> Are they both Dual 4 Ohm Subs?
> Enclosure alignments?
> ...



Both woofers are dual 1 ohm coil. Each sub's coils are wired in series, then the two subs run in parallel. I have two 0 gauge cables running from the alternator to the batteries...welder cable. Two 0 gauge lines of the same cable for both power and ground to the amp-so four 0 gauge cables connected between the amp and batteries. 8 gauge cabling for speaker leads. I'm not sure what you mean by 'enclosure alignments'... Each sub is in it's own vented box. The two boxes are nearly identical in measurements other than the port size/length. As for batteries, I haven't the budget for proper lithiums. They are essentially wired as 2 banks of 2...each bank as follows - one power lead from the alt, and one from the amp connected to an 850CCA lead/acid. That battery grounded to framework, and a large marine cranking battery connected in parallel with the first battery. Both grounds from the amp go to framework as well. The amplifier has a maximum current draw listed at 490 amps.


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## daloudin (Nov 2, 2020)

wolfrogers said:


> Both woofers are dual 1 ohm coil. Each sub's coils are wired in series, then the two subs run in parallel. I have two 0 gauge cables running from the alternator to the batteries...welder cable. Two 0 gauge lines of the same cable for both power and ground to the amp-so four 0 gauge cables connected between the amp and batteries. 8 gauge cabling for speaker leads. I'm not sure what you mean by 'enclosure alignments'... Each sub is in it's own vented box. The two boxes are nearly identical in measurements other than the port size/length. As for batteries, I haven't the budget for proper lithiums. They are essentially wired as 2 banks of 2...each bank as follows - one power lead from the alt, and one from the amp connected to an 850CCA lead/acid. That battery grounded to framework, and a large marine cranking battery connected in parallel with the first battery. Both grounds from the amp go to framework as well. The amplifier has a maximum current draw listed at 490 amps.


Given the amount and quality of wire you have from the engine bay to the batteries there's no reason not to have both alternators in parallel and take advantage of 280 Amps of charging current. What's the actual footage of wire from the Alternator to the Rear Batteries?

Enclosure alignment is what you mentioned; ported vs sealed and tuning. The reason for asking is due to impedance box rise which determines apparent load power and how "hard" the system is to work. If you give me the actual net volume and port tuning I can use WinISD to calculate the apparent load power of both drivers and then combine them to see what the amplifier is seeing at what frequency.

Since you're running ported I need the xover settings as well - Low Pass and Infrasonic High Pass.

CCA is not pertinent to audio installations - SLA batteries have built in resistance to current flow to keep the output voltage high in cold cranking situations so that a battery will still start the motor in sub zero temperatures. This is a measure of "one-time" output and not all manufacturers report the same standard:









RC or AH are much more pertinent to audio as is the internal resistance. Batteries like the XS Power XP AGM batteries (not a recommendation - just an example) are designed for low internal resistance to get as close to the advantages of LTO while maintaining the durability and power density advantages of SLA. It is likely that you could run a single quality AGM or LTO and get better performance than 4xSLA... but you could also add a SuperCap to the existing installation and get similar performance. So we need to get all the data in order to simulate both and see what "looks" the best given your setup.

Give me the actual make and model number of the batteries (All 4 if they are different) and having a marine battery or deep cycle battery are only necessary if you are running the system engine off with no charging for extended periods and need the voltage support (which begs for LTO due to the discharge curve.)


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