# Capacitor values

• posted
I'm using a Pyramid 35 Amp, 12-15 Volt power supply for my 'portable' sound
system. See here:
, and it's
been recommended that I install an electrolytic across the supply output.
The 4 channel, 12Volt amplifier is 'rated' at 350 Watts/channel into 2 Ohms.
I don't question the recommendation, but would like to be certain of the cap
values.
TIA
Joe Arnold
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Easy's getting harder everyday
• posted
• posted
Wow - that's about \$150. US Joe
• posted
Well, I assumed that you wanted something that would make a significant difference.
4 channels at 350W is 1400W, well over 100A at 12v. Your power supply is only rated at 35A surge, so isn't going to cope with anything like full output without sagging - even driving just one channel, come to that. So, if you are trying to improve the transient handling situation by adding a capacitor, it has to be a really big one....You still won't be able to drive your amplifiers to anything even remotely approaching full load, but will be able to get a lot more dynamic range.
• posted
Thanks for the attention Sue. I just didn't expect to spend that much. What about 2 or 3 mfd? :-)
• posted
Its a Pyramid brand amp. Don't forget to drop the zero from the power rating : )
• posted
If the numbers are accurate, then all the capacitors in the world won't solve the problem that the numbers say exists: Power output = 4*350 = 1400 watts. Power input = 12*35 = 420 watts.
Real world, unless your eardrums are made out of concrete, you're not listening to 1400 watts. How much input power you're using is anybody's guess, at this point. Whether a cap of any size would be beneficial is therefore unknown.
Ed
• posted
Thanks for the note Ed. I understand the math and reasoning, but on Saturday night, I took the system to a party and it got its first real workout. I couldn't give it a good hard 'push' here in my small 10' X 17' X 7' room, but the hall on Saturday was 36 X 75 X 12 feet, with about 80 people attending. My calibrated SPL meter gave me an A weighted reading of 107 db on the dance floor, 30 feet from the speakers. The bass was as low, clean and loud as I wanted, and the rest of the range was superb. I got complements all night on the sound. All in all, I was quite satisfied, which, after all, is the bottom line! Here's the layout:
The subs are to the right of the console. Joe
• posted
Joe, if you keep doing this sooner or later (probably sooner) you car amp is going to blow. you might as well get a real amp designed to do what you are asking it to do. check out the Behringer EP2500.
"A" weighted measurements of music don't mean a whole lot. "C" weighting would be more relevant.
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Hi Tim. Meant to type 'C' weighted. Just looked at the Behringer and the specs are great. So far, everything (lumber included), but the light chase, strobe, mirror ball & spot has set me back less than \$550, the amp being under \$150. I wanted the option of running off the car batteries (2). I think I'll look into getting the Behringer, or similar for indoors. I like the 'sound' of dependability. This whole thing is a work in progress, with almost daily changes and mods. It's been a blast. Joe
• posted
How true are the rated watts in the new audio equipment. I remember that some older equipment was rated 100 W and was enough to reach dangerous levels, not to mention giving you an hernia. This seems worse in auto and consumer audio.
Could it be that maybe they are rating the maximum instantaneous power under ideal conditions. Have seem some auto stereos rated 200 W and the size don't seem to match.
• posted
you might want to lurk a bit on alt.audio.pro.live-sound and/or read some relevant archives. just filter out the "mud" and "pick the cherries" if you get what i mean.
i have had pretty good luck on e-bay with used amps. mostly QSC RMX series and Yorkville Audiopro.

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