BHK Amplifier Longevity

Great if it works like that.

I was not sure if heatings are the only more expensive part or is there’s more.
I remember pure A amps also often have considerably more or bigger caps for a reason I don’t have a clue. I remember my Vitus amp had some large white caps costing well over 100$ each, my Lamm Hybrid M1.1 on the other hand had few smaller ones, so it’s maybe no question of high bias.

As always, parts don’t mean much at the end. And I agree with Arnie, high bias doesn’t mean, that speed and dynamics have to be great, too. Finally it seems to need the right parts, a good design and whatever bias providing further improvements.

There are people still using 50 year + old McIntosh amps in their system. Sure, the amps will need recapped, refurbished after a good number of years. However, that $500 amp in 1967 is a $5,000 amp new. If you are buying a BHL level component, I would expect long life much like the McIntoshes of the world. I would say in about 10 years, you may want to send it in for a general tune up-refurbish. The refurbish cost will be peanuts vs the MSRP of a similar amp at that time (even with shipping).

I think your idea of selling amps before they go out of warranty is an excellent one. I love a good, robust secondary market.

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Me, too, particularly if I don’t lose any money in the process.

I would call PS Audio directly and ask what they currently charge for repairing the products you have if they were out of warranty today.

I had my BHK300s for a year, and would still own them today’ if I didnt go through 3 different amps due to reliability issues. I am sure it is not the norm, but I had horrible luck with my BHKs. Such a shame too, as I really loved the sound of them.

BHK300s 16 months in system, 1,600 hours in use without an issue except one tube went bad with about 1,000 hours on it. PS Audio replaced both tubes in that amp and sent 2 replacements for the other without charge.

Orosie, I’m curious. Our situations can all be different. I don’t mean to be intrusive, just asking these questions to check on the possibility of heat as a causal factor? Did you suspect or were you told if the problems were related to heat? Were you told what caused the failures? Did your amps have clearance of at least 3 inches all around? Were they in the open or inside a cabinet? Did you have small fans cooling the heat sinks? What was the average temperature in your listening room? The highest temp? Were the amps on all the time? Did you use the button in front to put them on stand-by when not listening?

I’ve spoken to six manufacturers with amps that run hot. They all recommended turning off the units when not in use, on the grounds that among other things the caps can dry out over time. While a risk, it’s unlikely that heat would be a problem inside of a year, except for extreme conditions. Still, regardless of the reason communicated for the failures, I’d love to know the answers to the questions above.

I love my BHK 250 and run a small fan on either side. It runs very comfortably cool. Prior to that, heat sink temperatures could rise to 118 degrees, even though the amp has plenty of space around it in an open rack. My fingers could touch the sinks for about 7-8 seconds before they became uncomfortably hot. I subscribe to the never-turn-them-off and put them on standby for the reasons Paul has mentioned. My room temperature is a constant 72 degrees 24/7/365. I have a pair of M700s in my theatre room in case the 250 ever needs repair.

Thanks for your post. I hope to hear from you.

Best,

Armando

Hi Armando,

Left the amps on in standby whenever not listening. Basically turn them on mid to late morning, listening on and off all day, then turn off via blue button on front to put in sleep before bed.

Amps were adequately ventilated on amp stands, away from any other heat source. Room averaged 74-76 during the day…so heat was never an issue from an environmental standpoint. PSA said I had a couple of failed input boards, but beyond that I don’t know the exact specifics of the problems. I can tell you that one of the two original monoblocks never had one single issue. The other was sent back twice to be repaired, then replaced by a new one after the third issue, which went bad, and was replaced by another new amp, which finally seemed to fix the issues. By that point, I was done.

FYI, even in low bias, my JC1s run hotter than the BHKs ever did, and have never had an issue. These amps are designed to run warm to hot, and should not fail from doing so.

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For what it’s worth my BHK300’s are always switched on at the rear & on/off at the front only when it’s in use. Neither amp ever runs hot, only warm to the touch. They’re in an open back cabinet about 10" from the rear wall with 2/12’ clearance at the top, about 1 1/2" on the sides.

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I’m pretty sure that my BHK250s run at over 50 Celcius (i.e. over 120 F) - they’re off at present so I can’t measure them.

One of my BHK 300’s developed a strange crackle that sounded like static so it was hard to diagnose. Ultimately, PS Audio decided that it was the input board. Once replaced, it’s been fine. The other amp has been flawless. They’re out in the open on synthetic quartz pads. The room is always in the mid 70’s and the amps are warm to hot in spots to touch. Not exceptionally hot. I had a KRELL KSA 250 that I should have never sold. Flawless performance for 12 years and the guy I sold it to, sold it at a profit 5 years later. I would be hard pressed to decide on replacements. If they become problematic there’s a lot of great amps out there.

I used to have BHK 300’s and they never got more than slightly warm. They are class AB amps, leaving class A at around 1 watt, so where is this heat people talk about coming from?
Heat is not an issue with them or the 250.

Thanks for sending your rig pics, and thanks for your suggestion of the Berlin Philharmonic concerts. They’ve given me great joy! It is a treasure trove of good music.

I believe you when you say that your BHK’s run warm to the touch, even though having 1 1/2 inches of clearance to the sides I’m surprised. I would expect higher temps from those Mahler crescendos :slight_smile:

Perhaps not all BHK’s run at the same temperature and that is reflected in the cooling fins. Or maybe our hands and thermometers are not calibrated the same.

Who knows? All we can tell is that there appear to be differences in how we perceive the heat from our amps.

Good question. It may be that not all BHKs run at the same temperature, or require different cooling from the sinks based on factors like room temperature, or our hands have different sensitivities, or our thermometers are not calibrated the same or are of equal quality.

This hobby of ours can be maddening with all the variables that come into play, but that’s partly where the fun and the challenge comes from.

A definitive answer is almost impossible because a range of expected temperatures is not published, not is a reference point. Were those available from PS Audio we could make better judgements.

I recall Famavolat mention that Paul had referenced something like 123 degrees as a possible danger threshold but I did not dig back to learn more about the reference.

Ok, thanks.
But 123 degrees F is not likely. The amps just don’t get hot at all. Certainly not enough to hurt them.
Heat is not something to be concerned with in terms of the original question of longevity. I would expect these amps to run into our old age just fine.
I’m surprised no one from PS Audio hasn’t clarified this, it’s not a hard question. But many technical questions are left unanswered, which might be explained by the elimination of “ask the experts”…

Ask the Experts was discontinued at my request, at the suggestion of a fellow member. It was too much of a mishmash, hard to find anything, and James is already running around trying to be responsive. Do not read anything nefarious into the category’s disappearance.

Feel free to continue asking whatever you would like.

My feeling is heat may in fact not be a problem at all but it is certainly a subject that needs a little more elaboration, if only to allay the concerns of those who feel, rightly or wrongly, that their BHK’s run too hot. Like you said, it is not a hard question.

Elaborating on what is too hot would make us better informed. Not elaborating only arouses suspicion (I speak only for myself) that there is a heat concern. I did not know that “Ask the experts” was eliminated. That is disappointing.

I would have asked the experts if a new posting claiming there are no spare parts for the BHK if one needs repair is true. I can’t fathom it. So long as the BHK is being produced at least I would expect there to be parts. I would ask if they are they available for repairs. An untruth quickly put to rest is better than one that goes unanswered.

As this is of specific concern, send James an email and specifically ask. Or call PS Audio and ask.

Many questions here fall through the cracks for all sorts of innocent reasons.

I did with no replies. I posted here as a last resort. I should say no meaningful reply. Simply “It’s not a concern” is not a satisfactory reply.

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