Infinity PS-12 Powered Subwoofer Fired Amplifier

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

The time constant of C37/R121 determine how long the amp will stay on AFTERr the audio signal is no longer present, the larger the cap the longer it will stay on, the schematic shows 220uF, you can try 470uF for longer ON time.

YAY! Budm is here.

Do you have any idea why the volume would be lower than original considering we changed a few components (that we believe are equivalent) and used metal film caps (just for the bypass caps)?

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Yes, I'm pretty sure I got all of those caps. I ended up changing all the electrolytic caps except c64. I meant to change it too, but missed it.

I'll measure the +/- 15v rails.

Sorry, I quoted the wrong caps to test +/- 15V. It's C4 and C9.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Jiari,
Thanks for the clarification. I haven't had a chance to test. No worries.

Yes, glad to see bud here.

Wondering if the long leads on the 2 film caps are having any negative impact. I think in general you want short leads on caps.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Confirmed I replaced all of these caps:
C2, C4, C6, C8, C9, C35, C37, C78

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I'm an idiot. I just checked my speaker settings and my subwoofer was set 10 dB lower than my fronts. I set them to be equal. I also realized I was sitting directly across from the side of the sub and the sub was pointed toward 20 ft or so of open air. And since this is front firing, most of pressure wave had no place to reflect off of (though some hit the opposite wall about 4 feet away). I stood in front of the sub for a bit and the pressure wave on my ears was oppressive. My ears are still ringing 2 hours later. I was also able to get the sub to bottom out at full gain. I actually think my sub is working perfectly and the situation was really just my setup.

Glad to hear you replaced all the caps.

I think Budm was suggesting upping C35 so that the sub stays on longer between the times it sees a signal. I'm still wondering if there's a problem with the sub's signal sense circuitry.

I'm not sure the long legs of the Caps makes much difference in this case. From what I've read, the long legs will act like inductors, which will reject high frequency. However, we're working at pretty low frequency. I feel pretty confident that's not the cause to the issue you're seeing.

[sachs]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

You can also just completely bypass the auto sense circuit if you want (though not preferred). We should see if we find any other problems first.
I can post a picture of how to do it if you want to go that route. It seems that the signal reaching the sensing circuit is too low.

Please, can post a picture? or explain?

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Please, can post a picture? or explain?

FORCED ON circuit.

[sachs]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

[QUOTE=FORCED ON circuit.[/QUOTE]

Thank you. The sound of my PS410 is very good, no flaws and the only flaw is that the relay turns on and off in long dialogue movies. Any tips?

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Thank you. The sound of my PS410 is very good, no flaws and the only flaw is that the relay turns on and off in long dialogue movies. Any tips?

You do realize that the PS410's auto on/off circuit turns off after ~10 minutes of no signal. Dialogue should be going through your centers and I doubt your sub gets any signal during that time. The behavior you are describing sounds normal.

As Budm noted, you could change a capacitor so that the sub stays on longer after receiving a signal.

https://www.badcaps.net/forum/showpo...&postcount=140

[sachs]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

You do realize that the PS410's auto on/off circuit turns off after ~10 minutes of no signal. Dialogue should be going through your centers and I doubt your sub gets any signal during that time. The behavior you are describing sounds normal.

As Budm noted, you could change a capacitor so that the sub stays on longer after receiving a signal.

https://www.badcaps.net/forum/showpo...&postcount=140

Ok, thank you but the problem is the clic,clic of relay in long dialog time...sorry my bad english.

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

You need to check or replace C37.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I just checked my speaker settings and my subwoofer was set 10 dB lower than my fronts. I set them to be equal... I actually think my sub is working perfectly and the situation was really just my setup.

I think Budm was suggesting upping C35 so that the sub stays on longer between the times it sees a signal. I'm still wondering if there's a problem with the sub's signal sense circuitry.

I'm not sure the long legs of the Caps makes much difference in this case. From what I've read, the long legs will act like inductors, which will reject high frequency. However, we're working at pretty low frequency. I feel pretty confident that's not the cause to the issue you're seeing.

I've been busy so no time to pull the amp back out and investigate.

I agree that my sub also sounds good especially after tweaking it more (gain, phase, freq), but I'm having to run it with a +6.5db input wheras before repairs it was at +1.5db. Actually +5db is probably closer to equivalent, but I think it sounds better with the input a bit higher and the gain dialed back. I guess the input difference is okay just puzzling. One of the side effects of turning up the input (from receiver) appears to be less standby mode. I guess this could make sense with higher signal levels making it to the sub.

I think you are right about the long leads on the caps. I didn't think about that.

I'm happy with it right now and plan to just use it until I can get another opening to work on it.

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I've been busy so no time to pull the amp back out and investigate.

I agree that my sub also sounds good especially after tweaking it more (gain, phase, freq), but I'm having to run it with a +6.5db input wheras before repairs it was at +1.5db. Actually +5db is probably closer to equivalent, but I think it sounds better with the input a bit higher and the gain dialed back. I guess the input difference is okay just puzzling. One of the side effects of turning up the input (from receiver) appears to be less standby mode. I guess this could make sense with higher signal levels making it to the sub.

I think you are right about the long leads on the caps. I didn't think about that.

I'm happy with it right now and plan to just use it until I can get another opening to work on it.

Honestly, it's probably not worth the time to investigate. Glad everything worked out for you (and me).

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Honestly, it's probably not worth the time to investigate. Glad everything worked out for you (and me).

You are probably right. We'll see how it performs over the next few months, and if it continues to be solid clean Bass then we'll probably just use it. Really appreciate the help! It was very good having someone else walk through the repairs at the same time. We could not have timed that any better.

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

You are probably right. We'll see how it performs over the next few months, and if it continues to be solid clean Bass then we'll probably just use it. Really appreciate the help! It was very good having someone else walk through the repairs at the same time. We could not have timed that any better.

Aw crap. I just realized that I didn't vet TIP41C vs TIP31C (original) like I vetted the MOSFETs. The gain on TIP41C is lower than TIP31C and it is used to set the VCC of IR2111. That drives the downstream circuitry that actually powers the speaker. I would hazard a guess that is the source of the lower output.

I'm working on fixing a different amp. When I buy parts, I'll replace TIP41C with TIP31C. I'll let you know how it goes.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Aw crap. I just realized that I didn't vet TIP41C vs TIP31C (original) like I vetted the MOSFETs. The gain on TIP41C is lower than TIP31C and it is used to set the VCC of IR2111. That drives the downstream circuitry that actually powers the speaker. I would hazard a guess that is the source of the lower output.

I'm working on fixing a different amp. When I buy parts, I'll replace TIP41C with TIP31C. I'll let you know how it goes.

I stuck with the TIP31C part number. I thought you did too based on your parts lists:

Here's my order (quantity in parenthesis) [Description; board references]:


(2) 942-IRF640NPBF [MOSFET; Q18, Q22]
(1) 610-CEN-U07 [BJT NPN; Q2]
(1) 610-CEN-U57 [BJT PNP; Q3]
(1) 863-TIP31CG [BJT Bipolar, Q4]
(2) 647-UVY2A332MRD [100V 3300uF; C6,C8]
(1) 647-ULD1H4R7MDD1TD [50V 4.7uF; C2]
(2) 647-USV1E220MFD1TE [25V 22uF; C4, C9]
(1) 647-UVZ1C331MPD1TD [16V 330uF; C12]
(1) 647-UVY1C221MED1TD [16V 220uF; C37]
(1) 647-UPW1E100MDD1TD [25V 10uF; C35]
(1) 667-ECQ-E1475KF [film capacitor 100VDC 4.7uF; C73]
(1) 667-ECQ-E1685KF [film capacitor 100VDC 6.8uF; C72]
(10) 749-9911-312 [.312 standoffs, nylon]

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

I stuck with the TIP31C part number. I thought you did too based on your parts lists:

You're right. I'm going crazy. Too much work plus 9 month old. Thanks for verifying.

[Jr_ece]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

Good times but tiring.

[budm]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

BTW, Q2, 3, and 4 for the power supply regulation will not affect the Audio amplifier gain, it will affect the maximum audio signal level before clipping. The gain are set by the negative feedback, so if you have to turn up the gain then something has change in the gain stages. Since we are also dealing with low frequency only so if the coupling caps with between each stage has lost it capacitance the you will lose Low frequency.

[jiari]

Re: Infinity PS-12 Powered Subwoofer Fired Amplifier

BTW, Q2, 3, and 4 for the power supply regulation will not affect the Audio amplifier gain, it will affect the maximum audio signal level before clipping. The gain are set by the negative feedback, so if you have to turn up the gain then something has change in the gain stages. Since we are also dealing with low frequency only so if the coupling caps with between each stage has lost it capacitance the you will lose Low frequency.

Thanks Bud. That's helpful. I wouldn't have guessed about the bypass caps and passing low frequency.