Hafler 9505 capacitor replacement recommendation

[AnalogSteph]

I don't know why the rectifier is even being discussed here. Peak charge current is generally limited by secondary winding resistance so can never get arbitrarily large (and with 20000 µF you're close to maximum as-is), and it's not like the replacement caps proposed so far have been wildly different from the originals - in the world of electrolytics, +/-10% in capacitance is basically nothing, that's not even the parts tolerance in many cases. If you can find some good, 18000-22000 µF, 100 WV parts that fit or can be made to fit easily, go ahead.

In this price class I would be thinking about performing some ESR and leakage current (near rated voltage) tests on the other existing caps. On this end of the bathtub curve, really all bets are off as to what you might find. I wouldn't be above swapping just two belonging to one channel if at least two others are testing to be in perfect health.

 

[Doodski]

Peak charge current is generally limited by secondary winding resistance so can never get arbitrarily large (and with 20000 µF you're close to maximum as-is), and it's not like the replacement caps proposed so far have been wildly different from the originals - in the world of electrolytics, +/-10% in capacitance is basically nothing, that's not even the parts tolerance in many cases. If you can find some good, 18000-22000 µF, 100 WV parts that fit or can be made to fit easily, go ahead.

I disagree. Downgrading the caps to 18,000 µF in this kind of amplifier is tacky if not silly. The upgraded bridge rectifier has a cost of about $3-$4 and it's good practice to upgrade it. The secondary winding resistance is a unknown value and making assumptions regarding that to save $3-$4 is not practical. The upgraded Nippon Chemi-con caps @ 22,000 µF 100WV have a capacitance tolerance of -10 to +50% (T) (10 to 250Vdc) (at 20℃, 120Hz) so that means the difference is at best ~18% increase over the 20,000 µF stock caps. For what it is worth gambling on a at best case scenario ~18% increase to save $3-$4 is not reasonable. @restorer-john advised to replace all 4 caps and I think that is good practice as well. It's not like we are on a limited budget repairing a cheap inexpensive product. The amplifier in question here is a nice unit, needs a long term fix, deserves a proper repair with the integrity to match and having mismatched caps sticking out of the amplifier (if machining is required) is not a very nice repair job. I've been advised by the powers that be (My electronics instructors from when I studied.) to upgrade the bridge if increasing the capacitance and so that's what I would do.

http://www.chemi-con.co.jp/e/catalog/pdf/al-e/al-sepa-e/006-screw/al-lxalg-e-2020.pdf

 

[fredoamigo]

Hi guys ...

since yesterday evening i have a little problem with my 9505 and i can't find the solution?

I have very audible murmur( a breath ) on one side of the speakers of course I switched the cables and the breath comes from the right side of the amp ... one thing that surprises me is that before, I had a small noise of " big ploc" at the extinction of the amp and now nothing more?
It is my DAC RME ADI which acts as preamplifier think that the concern can come from there?

this morning, I opened the amp, I looked and everything is like new, the capacitors are not deformed, I cleaned everything with compressed air, everything reassembled, and of course the problem of audible breath on one side and still there.

Anybody here has already had this kind of problem ?

the time has come to replace this amp ?

I've had it for 15 years and I'm attached to the mosfet

 

[DonH56]

Hi guys ...

since yesterday evening i have a little problem with my 9505 and i can't find the solution?

I have very audible murmur( a breath ) on one side of the speakers of course I switched the cables and the breath comes from the right side of the amp ... one thing that surprises me is that before, I had a small noise of " big ploc" at the extinction of the amp and now nothing more?
It is my DAC RME ADI which acts as preamplifier think that the concern can come from there?

this morning, I opened the amp, I looked and everything is like new, the capacitors are not deformed, I cleaned everything with compressed air, everything reassembled, and of course the problem of audible breath on one side and still there.

Anybody here has already had this kind of problem ?

the time has come to replace this amp ?

I've had it for 15 years and I'm attached to the mosfet

Several things can cause strange sounds. It would be helpful if you could describe it in more detail; "breath" does not tell me much. Hissing, rumbling, is it constant or cyclical, etc.?

Turn everything off and swap connections from preamp to amp to verify it stays with the right amp channel and is not in the preamp.

 

[fredoamigo]

Hi Don .
It is not a sizzling but a breath a bit like a constant pink noise very audible but not in interaction with the volume that is to say, if I increase the volume, the breath does not follow, is not stronger, remains constant.

I have already turned off everything, and switched the cables

What I'm wondering about is that the 9505 doesn't have a relay and so, before this problem, I had a shutdown noise when I stopped the amp on the speakers (a ploc) and since I have the audible murmur problem, I don't have any more noise when I turn it off?

 

[DonH56]

Hi Don .
It is not a sizzling but a breath a bit like a constant pink noise very audible but not in interaction with the volume that is to say, if I increase the volume, the breath does not follow, is not stronger, remains constant.

I have already turned off everything, and switched the cables

What I'm wondering about is that the 9505 doesn't have a relay and so, before this problem, I had a shutdown noise when I stopped the amp on the speakers (a ploc) and since I have the audible murmur problem, I don't have any more noise when I turn it off?

I have dealt with symptoms like this in the primordial past and IME a "pop" can be a lot of things, including a bad diode, bad capacitor (which may or may not exhibit any visible signs), or bias component that impressed a spike on the output at turn-off. I would look for a good repair tech who can troubleshoot and fix it for you. The good news is that constant bugs are easier to find and fix than the "every once in a while" kind.

Not having a relay is not bad in itself; many amps have more sophisticated protection circuits including your Hafler, and relays can fail too so are not a complete panacea.

 

[SirPaulGerman]

Wow. Okay. Clearly you're knowledge and experience is far beyond mine. I am humbled.
So it appears we may be on to a (combination) solution.
You guys are great. Thank you for your time.
Funny thing is, where'd the OP go?

What power capacitors did you use in your Hafler ?