My Pass also does the same click (more like a ringing) after certain time its turned on and off as well. I always thought it might be the caps charging/discharging inside. Glad to know that its the heat sink…
pmotz said . . . it only does it once, perhaps only one heat sink is making the noise?One heat sink may get warmer than the other, depending what is inside next to it.
Could it be the tube making a ‘ping’ after getting hot?
I have a Classe CA400 that exhibited the same sound.
It was the cover expanding after warm up.
The screws were quite tight, I made them just snug and the click was gone.
How in the world did you figure that out?
I’d be shocked if it were a tube, the sound seems to loud to be the expansion of such a small and delicate device. I doubt it is the top since I believe it is made of MDF. Tomorrow when I turn the system on I will try to remember to listen close.
pmotz said The heat sinks could be it, the odd part is it sounds just like a relay. The other thing is it only does it once, perhaps only one heat sink is making the noise? I should try sitting next to the amp at the appropriate time to see I can discern where it is coming from.There are only two relays inside the BHK. One controls the bias current so it goes up and down according to the setting of the front panel standby button, the other shuts off the outputs. Since music's playing, it certainly can't be that one. If, for some reason, it is the bias set relay mysterious engaging, then I would expect the amp to cool down tothe same heat level you have when the amp's in standby.
Thanks for the info Paul! The heat sinks do seem to be much warmer in operation mode, but I will double check this. With regard to checking for heat sink noise, I forgot to get up close and personal with the amp the last couple of mornings (it takes longer and longer for me to wake up as I get older, bah!), but I did restart it after a several hour stand by period while I was at lunch. I didn’t get the snap this time, but I touched the cooling fins after about 35 minutes (maybe too soon) and one made (I think) a very faint pop. Not enough to convince me that is the source but I will try again in the morning when it has longer to cool down.
Last week I did get a chance to listen to the click. I was touching the heat sinks lightly, I heard the click but didn’t feel it. Sounded internal, but wouldn’t swear to it. It also was lower in volume, which would make sense if I was touching the heat sinks and relieved some of the stress. I didn’t get another chance to check since I went to AXPONA on Friday. As my usual practice when I go away for more than a couple of days I shut the amp down (turned off switch in back). When I went to turn it on this morning I didn’t notice if I got the initial blinking light, but pressing the front panel switch resulted in nothing. I could hear a very low level buzz so it was getting some power. I checked all the fuses and found the 1.6A power input fuse blown. Not sure why that happened, no power surges to the house while I was gone best I can tell. I’m going out in search of a cheap replacement this afternoon. Curious if any other BHK owners have experienced a blown fuse?
Never blown a fuse on my BHK250. So far anyway. I have had it trip off a couple times with what seemed to be minor, or no, provocation.
pmotz said Curious if any other BHK owners have experienced a blown fuse?No, never. BHK 250, here. But I do leave it on all the time and turn it off only when on long vacations. All power surges have to work through the P10 (and we have a lot of those) but the BHK seems just fine.
–SSW
I went to the local Radio Shack this afternoon and could not find the appropriate fuse, the closest I found was a 2 amp slow blow with clear glass. I did not see anything with “H rated” on it or anything “rated” period. Not sure what this designation means, but the original one is ceramic so maybe that’s it? Anyway, I decided to call PS Audio to see what they had to say. I talked with Scott (McGowan?) and he said they have upped the fuse size to 2 amp and he would send me some. I put a clear glass one I got at Radio Shack and the amp works again! I’ll put the one Scott sends me in as soon as it arrives to be safe. While Scott did not say so, I would presume the 1.6 amp fuse was marginal for in rush current so they increased it to 2 amps to be prevent unnecessary failure. Now I can get to my intended plan of cranking it to 11 to simulate listening at AXPONA!
I was one of the early BHK 250 Amp Betas testers. Like so many other Beta Testers, I was excited with the results of this amp compared to my baseline amp (see my previous review). But, not long after the Stereo Amp was offered, the BHK 300 Mono amp was made available. Having been a long-time Infinity Speaker owner, lots of clean power has always beneficial. But, I felt like I was missing something not owning the BHK 300 Mono amps.
So, after 300+ hours on the BHK 250 Stereo Amp, I made the decision to invest in the BHK 300 Mono Amps. After the Mono amps showed up, I hooked them up and Oh My Gosh! Right out of the box (as amazing as the BHK 250 Stereo Amp has been) the BHK 300 Mono Amps were another huge improvement.
The sound stage opened up even more. The additional power was very noticeable. It was like having the 300 hp V8 under the hood of your car. You have the power to do whatever you want. It’s no problem. It was surprising to me, how audibly apparent having that power in reserve was.
As wonderful as the BHK 250 Stereo Amp was (truly amazing), I can easily recommend to anyone on this forum that the BHK 300 Mono amps are well worth the investment.
Me too!
Well I haven’t had any more fuse issues with my BHK 250, but in the last few months I have occasionally heard a hum coming from somewhere in the system. It was always a brief thing, then it went away and so did my interest in finding it. Yesterday I was reading the paper and the CD I was listening to ended. Rather than get up and play another CD I just read in silence (unusual for me). In a general sense the system was silent, there may have been a slight steady sound, but between my tinnitus and the minor background sounds of the house and outdoors I didn’t think it was in any way annoying, distracting, or even noticeable. But then, for a brief moment I heard a hum. So I listened a little longer and there it was again. So I decided to time it to see if it was a regular cycle; indeed ot was. It was about every 2-1/2 minutes, not precisely 2-1/2 minutes every time, but within a few seconds. The hum lasted 3-5 seconds, rising up then falling off. I checked a few things to determine if it was in the system (i.e., a ground loop) or in the amp. It was in the amp. In very close listening the amp has a constant hum, I assume it is the transformer which is Ok, I can’t hear it as a distinct sound from my seat. But the cyclic hum also sounded like the transformer and could be most definitely heard from my seat. The worst part is now that I have “found” this hum I can hear it when music is playing at low level. Kind of like when you finally hear that subway or traffic sound everyone mentions on the old RCA and Mercury recordings (others too, I’m sure) and you can’t not hear it. My bubble has been burst (sort of).
I have heard “rumors” of transformer noise, but strangely I haven’t read them here, I read them on Audiogon. Surely there is at least one incidence of this to justify the rumor, right? So my question to other BHK 250 (and presumably 300) users is, have you experienced this? Next, and obvious, question is how to fix it?
I owned a Edge amp for many years and it to would hum on occasion also. I would mostly notice it when the amp was idle. The hum was sometimes very low in level and other times high in level. But mostly annoying. I called Tom Maker (owner)about the humming issue and he said that most of the time the hum was due to the power company’s dirty ac (see edit) affecting the transformers in the amp. Not being a EE…I left it at that and took his word for it.I was lucky that the hum would last on average 10 to 45 minutes. Other times for a day or so. Luckily this would only happen maybe 2-3 times a year. The only way the hum could be cured was to lift the ground on the amp. Worked like a charm but not recommend for obvious reasons . Also, if I unplugged the amp for a while and fired it back up the hum would go away,not always… but sometimes. Good luck.
edit… Thinking about it some more,maybe Maker said it was a incoming voltage drop/sag causing the hum. Can’t remember. 
Mark-d, thanks for the reply! Surprises me no one else has responded yet. Thought at least Paul would chime in. It could be a power supply issue, more than likely something in the house that is doing something at the 2-1/2 minute intervals. One thing I could try is run it off one of the P500 Ultimate Outlets, not sure how they deal with this sort of issue, but it would be fairly easy. I also have been considering a P10 given the sale price, but would like some assurance that it could solve the problem before investing. I will say I think the power I get is fairly good, I’m in a residential neighborhood of single family houses. Maybe four homes connected to the transformer. Anyone else …?
I had a Naim DAC that did this, Naim told me it was 99% of the time caused by the power source. And an audio friend who specializes in noise reduction said this,
'normally it comes from half wave rectifiers used for heating. Could be clothes dryer, toaster oven, pool or hot tub heater, baseboard electrics, etc. Sometimes an electric motor can lose part of a winding and still run, but it unbalances a line or neutral and it will hum.
Try it at your neighbors. If it hums there you should report it to your electrical utility. Global DC on the incoming service can be an indication that they could have a distribution transformer go down’.
However I have never had mech hum on any of my other gear.
pmotz said Mark-d, thanks for the reply! Surprises me no one else has responded yet. Thought at least Paul would chime in. It could be a power supply issue, more than likely something in the house that is doing something at the 2-1/2 minute intervals. One thing I could try is run it off one of the P500 Ultimate Outlets, not sure how they deal with this sort of issue, but it would be fairly easy. I also have been considering a P10 given the sale price, but would like some assurance that it could solve the problem before investing. I will say I think the power I get is fairly good, I'm in a residential neighborhood of single family houses. Maybe four homes connected to the transformer. Anyone else ....?Hi Pmotz, sorry, I missed this one. It sounds like you're thinking the hum is coming from inside the amp? That would indicate there's a power issue like something turning on and distorting the waveform (most likely). And yes, the P10 would certainly fix this.
If you do try one to see, you can always return it if it doesn’t help. I will tell you this, the BHKs sound amazingly better powered with a P10 - for what that’s worth.
I tried the BHK 250 on my P500 and found the Ultimate Outlet did not filter out the noise but the filtered outlets did. The only problem is while playing with this is discovered the transformer of the P500 is also making this noise! I also discovered that the P500 will power the BHK, but nothing else and probably not for very long. I never used it for playing music, just idling, but when I plugged my plasma TV in it went into overvoltage after a wile.
So a P10 is the best solution, except … Paul can you confirm that the P10 would not be susceptible to power line noise in the transformer?