Amplifier Gain Issue

[slikrider20 10+ year member]

Right now, I have an older TMA 1000.1 and i've been trying to set the gain on it with a DMM. I have no problems whatsoever reaching the desired voltage on my other amp. Both amps are sharing the same ground.

With The TMA 1000.1 amp, when I have the gain at 0, the voltage is ridiculously high (like 100+ AC volts) and when I turn the gain up, the voltage goes down, which is bizarre. But this doesn't correlate to how the sub sounds, when I turn the gain up - the sub gets louder and vise versa. What the heck is possibly going on here? I'm stumped.

Also - just to confirm. The way I would calculate the voltage I need to reach on a 2 channel amp that has one gain control and does 115x2 @ 4ohms would be to take 115x2 for a total of 230, then take that times 4ohms for a total of 920? Then sq rt that and get 30.33 volts, correct?

Edit: ^ I had that wrong. I don't multiple the 115 times both channels, I just take 115watts x 4 ohms and take the sq rt of that for a total of 21.45 volts.

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[slikrider20 10+ year member]

I'm starting to wonder if it's my cheap RCA cables that are the culprit. I noticed my front speakers cut in and out sometimes, other times they won't at all, and there is a slight hissing sound you can hear at low volumes. I have the knuconceptz bassik and they are only like $5.

Can I just get a 4 channel quality rca cable and run 2 channels for my front amp and the other for my sub amp? What cable would you recommend? Any advice is appreciated...

 

[Zero_Ohms]

As far as RCA cables go I personally like the t-spec ones. Any higher quality RCAs should work fine tho. Have you checked all connections? Are your RCA cables ran next to your power wire? This can introduce noise into the system. The amps should not share the same ground point. You should set your head unit to 3/4 volume and turn off all eq or set them to 0 bass, treb ect. Now take the RMS of the amp and multiply by the resistance and the square root of that number is the voltage you are looking for. Are you hooking up the dmm to one channel or both of them bridged?

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[slikrider20 10+ year member]

No my power wire is all by itself. I'm really starting to think my cheap rcas are a problem. I swear my speakers sound different every day. Gonna swap those out and see what happens.

I think I have a bunch of old treo rca I can start with before I buy something. Have you tried anything else besides t-spec to compare it to? I know a lot of people rave about stinger.

 

[bgowdy 5,000+ posts]

No my power wire is all by itself. I'm really starting to think my cheap rcas are a problem. I swear my speakers sound different every day. Gonna swap those out and see what happens.
I think I have a bunch of old treo rca I can start with before I buy something. Have you tried anything else besides t-spec to compare it to? I know a lot of people rave about stinger.

what are you setting the DMM to... Im asking because i have not done it in so long that i cant remeber what its suppose to be set on to sets amps this way lol

 

[slikrider20 10+ year member]

Well I replaced both RCA cables, and looked into my grounding spot. I had both amps grounded to the same spot so I decided to unhook the ground to my sub amp to see if the whine in the speakers went away. It went completely away with just my speaker amp grounded. So I thought i'd try a seperate ground (about 1 ft away) for my sub amp; grounded it there and the whine is back. What gives? Do I need to make a ground further away?

 

[slikrider20 10+ year member]

Also, when I leave both amps grounded and powered on bug remove the rca cables for the sub amp, the noise also goes away.

 

[big bass joel 10+ year member]

what deck you have?try grounding your rcas on the back of your deck?

 

[slikrider20 10+ year member]

Pioneer 80PRS. i've never heard of doing that ^^^ but I did a quick search and it seems pioneer is notorious for that. I'll look into trying that. Thanks

 

[slikrider20 10+ year member]

For the sake of starting a new thread:

Right now I have Morel Tempo 5 components powered by a PPI 350.2. PPI has some dirt cheat amps - it sounds really good to me but I don't have much to compare it to, with these fronts anyway. Do you think i'd notice a difference by upgrading my front amp to something a little nicer? The Zapco studio X series amps look pretty nice.

 

[Jeffdachef 5,000+ posts]

For the sake of starting a new thread:
Right now I have Morel Tempo 5 components powered by a PPI 350.2. PPI has some dirt cheat amps - it sounds really good to me but I don't have much to compare it to, with these fronts anyway. Do you think i'd notice a difference by upgrading my front amp to something a little nicer? The Zapco studio X series amps look pretty nice.

Would a a slight but noticeable improvement