Punch 45HD and 75HD noise issue need some advice/guidance..

[sangellga 10+ year member]

Hello all, I hope someone may have some suggestions for me because I can't believe I could be this unlucky! (Then again I am a very unlucky sort)

I have purchased some vintage equipment over the past few months. Gear that I either used in my youth or couldn't afford at the time and just wanted to own one for my collection. Plus I am planning an old school system build in an 04 Silverado very soon. Anyway........

As part of these purchases I have obtained a 45HD and a 75HD. Both are in excellent cosmetic condition for their age but I would not classify them as "Mint" and you can tell they have both seen at least some use. When connecting either of these amps to a pair of subwoofers, really just for testing, I can hear an audible noise coming from the subs. I have tried with low signal and even with no RCAs connected and the sound persists at low levels. Nothing really bad but loud enough to be annoying. Once I start turing up the volume the noise is covered up but during silent passages you can be sure it is still there. I have have connected several other amps to the exact same power, inputs, speakers etc with no noise at all. (Orion, PPI, Arc Audio, Phoenix Gold etc) Anyone have an idea what could be causing this? Or can I suspect some form of needed repair on both amps? I am sure this is a possibility but both amps, from different sources with the same problem was hard for me to swallow.

Thanks in advance for any advice.

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[sangellga 10+ year member]

I should add that the noise is like a low his. Almost like really low pink noise or static.

 

[CL1CKCLACK 5,000+ posts]

those amps are older then me. i think its time to get some new ones.

 

[sangellga 10+ year member]

LOL, yea, they are a bit old. But if you have not heard what these old school amps can do then you should check it out. Like I said these are for a second system in my Silverado. My primary system is Arc Audio and soon to be Hybrid Audio components. Still would like to find the source of the noise. My 225 HCCA amp is same age and pounds my 12s, as does the other Orion amp, PPI amp and my Phoenix Gold. It is just these two Fosgate amps that have the noise.

 

[Louisiana_CRX 5,000+ posts]

if both amps are getting the same noise...i'd suspect something else is causing the problem

 

[sangellga 10+ year member]

Yea, that is what I thought to. But i tried different ground points to eliminate any possible ground loops and the the nosie is the same both with and without the engine running. I guess maybe I need to carry them somewhere that has a dc power supply and test them. Eliminate the car environment and see if the noise persists.

 

[david in german 10+ year member]

CHeck the gains on the amps if you got them from the same source they may have damaged the little gain knob by turning it too much. hook them up and gently adjust the gains a little in both directions, you may find that the gain knobs just have a but of dust in them (I have before) and it needs to be worked out. Congrats on the old school purchase too! //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I am addicted to my old school collection. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif I have too many Old School Fosgate amps..

 

[sangellga 10+ year member]

Well they did not come from the same source but I think both have been idle for some time. Thanks for your suggestion. I will try that. Both of these amps have the recessed gains that you have to adjust with a very small flat blad screwdriver. Sure won't hurt to try.

Thanks

 

[gunz4me2 10+ year member]

It's possible it is the input filtering caps that went bad on them. After all, you are at the point where the electrolytic capacitors will normally start drying out due to age.

I just hope none of your driver cards went bad because those have been hard to find for at least 3 or 4 years now. They can be rebuilt, provided they aren't burned to a crisp.

 

[sangellga 10+ year member]

I think I may give Larry at Landis a call and see if he would bench them and then let me know if it is something that requires repair. I can then go from there I guess. I already have a price from him on the 75, the 45 probably is about the same price to repair. /sigh

 

[bigdwiz 10+ year member]

I think I may give Larry at Landis a call and see if he would bench them and then let me know if it is something that requires repair. I can then go from there I guess. I already have a price from him on the 75, the 45 probably is about the same price to repair. /sigh

As of last check with Landis, $110 for P45, $140 for P75 and $160 for P150....ka-ching!

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[RFCV 10+ year member]

But if you have not heard what these old school amps can do.. then you should check it out.

//content.invisioncic.com/y282845/emoticons/iagree.gif.15d6c075ee8d3913ba26866d06993068.gif

 

[gunz4me2 10+ year member]

Oddly, I was never a fan of the HD series because I had the original and 2nd generation Punch series amplifiers. I did own a Punch 30 HD and a Punch 150 HD and had issues with both of them whereas my prior generation OG Punch amplifiers rocked on. I did have to build a shroud for the first gen Punch 150 because it ran too hot for me at 4 ohms bridged, but the next generation punch 150 (just prior to the HD line) was my favorite generation of Punch amplifiers. I had six Punch 150s, two 75s, and one 45 from that particular generation and I regret selling them all.

 

[RFCV 10+ year member]

The good thing about the generations of RF amps in the 80's before the HD's was the 4 internal fuses for maintenance