New BHK Pre and 300 owner. Possible issues

Hi all. I just purchased a brand new BHK pre and 300 monos. I am coming from an all tube raven audio integrated.

First issue I noticed is one of the monoblocks (we will call this one the right one), shut off twice during power up. The logo would flash then just click off.
Once everything had powered on I noticed a problem from the left 300. VERY loud hissing noise from the left speaker. The right had some noise but nothing like the left. With the preamp muted it was still there and very audible from the seating position. As soon as preamp was brought out of mute it just got much worse.
Also, is it normal for the preamp to make audible clicking noise through the speakers with each increment in attenuation?

And finally, I powered down the tube stage via the button on the front for now just because this all didn’t seem right. Equipment has been powered on now for 45 minutes (via rear panel switch) and I noticed that the left monoblock that was creating the hissing noise currently has one heatsink that is very warm and the other is pretty cool. For comparison, the right monoblock which is in the same power state has both heatsinks very cool to the touch.

Any help would be really appreciated.

Try disconnecting the RCA or XLR from the amps. See if you are getting the same issues. This will eliminate the preamp as a possible issue.

You can then try powering down the amps and swapping the tubes. Again see if there is any change.

Edit: yes the clicking / popping noise is normal.

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Thanks for the quick reply. Since my post I went back to trying different things and did try what you suggested. Unplugging the rca from the amp removes most of the noise. I can still hear hissing from 2-3’ away but not like before.

Back to my original post, one of my original issues seems much more of a concern now that the amps have been fully powered on for 20 minutes.
Right amplifier - both heat sinks same temp, just a little warm to the touch.
Left amplifier - left side heatsink warm to touch like other monoblock. Right side heatsink nearly gave me second degree burns (slight exaggeration, but it is very hot, cannot hold my hand more than 5 seconds).

Edit - Ok, I cannot even touch the one side of the one amp now it is on fire. Everything powered down completely. Something is clearly wrong with this amp and it seems the preamp is creating the hissing.

Try using XLR cable, my 250 was very noisy with RCA too. It’s not good that PSA basically ignore RCA testing, imo. I understand your frustration… How efficient are your speakers?

The heat is defiantly an issue, I don’t have the 300, but my 250 was always luke warm to the touch. Sounds like one of your 300 is also just warm to the touch too.

I would send it back before the 30 days trial.

I only have two sources, dac and turntable and both are single ended.
I know balanced is praised as being superior but single ended should not pose this sort of problem.

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I had the exact same problem - roasting hot on one heat-sink - third degree burns hot!! … PS Audio sent me new amplifier boards and heat-sinks which I replaced by myself…
Preamp: are the tubes seated properly, and check the tube boards that stand vertically behind the tubes that they are located securely. I have a lot of experience with BHK amplifiers…!

Agreed, single-ended should not be an issue and you should not have the other issues you are experiencing.

Forget all the other cable issues, etc.
These amps are only biased class A to about 1 watt. They should not get that hot; certainly unevenly as you describe. I used to have them and they only ever got warm to the touch.
Unplug them and call PS Audio.

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[quote=“robbbby, post:1, topic:16802”]
Also, is it normal for the preamp to make audible clicking noise through the speakers with each increment in attenuation?

No such noises in my current system (BHK300’s & Audio Research LS28 preamp) or any system I’ve ever had. I can’t imagine this is normal.

Yes, the BHK preamp volume control makes a delicate little noise with each increment.
Once that’s understood as normal, you’d miss it if it was gone.

Thanks. Should I contact psaudio or will somebody from there reach out to me. I’m not sure how well these forums are moderated by staff.

I will check the tubes in the pre. They came preinstalled so I never opened anything.

The clicking is with the bhk pre.
It was ignorant on my part to ask about it before searching. It’s clearly well documented here and is normal. Not an issue for me, I have a bent audio tapx pre with slagleformers that also makes audible clicks.

Yes. Best to contact PSA The tubes and boards can work loose in transit.
I live in the UK, hence why I do my own repairs, etc. Definitely a fault with the power amplifier channel.
Clicking noise with preamp volume adjustment is normal.

A few things. Very sensitive speakers can have more hiss. I had tubes that amplified the clicks on the volume button. The one at 53 is part of the design. That one is there no matter what, but it should be mild. If you have some other tubes try that for the clicking. As for the 300’s there is one side on the heat sink that is warmer than others and that’s normal. It can be fairly warm but should be touchable. The factory can adjust the bias to address that. I’m surprised that this stuff isn’t caught during burn in.

Call them. Their service is excellent.

While PS Audio staff and Paul watch the forum they do not catch everything so it is best to affirmatively make contact with them.

If you want to contact Paul directly, his email is

I have had revel studio 2’s for many years and many amplifiers and never had hiss like this.
I unfortunately don’t have other tubes, I figure they’d ship with decent tubes that aren’t noisy.
I’ll definitely double check everything is seated properly before assuming I need to tube roll already.

The overheating definitely is not normal though. I’ll call PSA on Monday and hopefully get things sorted out.

My biggest concern is the hissing though, I thought these amps would be dead quiet, at least most reviews claimed they were. Even with input unplugged from amp I can easily hear noise from 2-3’

Fingers crossed

How do you like the studio 2s?

I’ve really enjoyed my experience with them.
I’ve owned them for over 7 years now and still haven’t had the itch to upgrade.

So did some of the other recommended things here but nothing helped.

Removed tubes from preamp and actually swapped them seeing if hum/hiss would switch channels but it didn’t. Nothing else in preamp from what I could see that could need to be reseated.

Also removed tubes from amps and swapped them.

When the amplifiers finish their warm up they both hum/hiss at relatively the same level, which to be honest, is still pretty darn loud. As soon as the preamp finishes warming up and clicks on, the left channel nearly doubles in hum/hiss noise.

Thanks to everyone for all the help/advice, really didn’t expect so many responses in such a short amount of time, seems like a pretty great community.