I would order a new set of tubes for the amp before I paid over a hundred dollars to send it back. Cost is less and way easier on time and his back. By the way what are the 90db speakers you are using with the BHK pair that you say are silent. His experience exactly matches mine and several other owners in this thread. Ideally a gain figure below 10 db would have been a better match for the BHK amps but it is what it is.
Ok, technically the Tungsram PCC88 they are 6-7 volt tubes, and BHK himself recommends them.
So which component should I NOT return?
The Tungsram’s are 7 volt tubes so on the outside edge of acceptable tubes. They were his preferred tube in the amp where they are fine but most of us have not found them to be so in the preamp. When the pair I have had in the amp for two and a half years wear out I won’t buy anymore.
The Tungsram indeed are the ones BHK likes in the preamp, but, they are noisy! I only use 12au7s, they are a better match in my system.
I would suggest returning your DAC, if, it’s not completely silent without the pre in the loop.
I would order a new set of tubes for the amp before I paid over a hundred dollars to send it back. Cost is less and way easier on time and his back.
He already tried a different set of tubes. If he buys another pair and it doesn’t make any difference, he has paid the cost of the tubes plus he will have to pay the amp return costs. So that doesn’t really make sense.
By the way what are the 90db speakers you are using with the BHK pair that you say are silent
PMC MB2SE speakers as if that actually makes any difference. Also never said they were silent. They are silent from my listening position but at high volumes I can hear the hiss if I put my ears against/ very close to the speakers (within inches).
His experience exactly matches mine and several other owners in this thread.
That doesn’t match my experience or that of several others. I don’t expect prominent hiss in any amp (tube or otherwise) at this or any other price point. Not sure why this is so hard to understand.
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I’m using the standard tubes right now so maybe that is what is making my system quiet compared to some of the rest of you.
I couldn’t get hold of the Tungsrams. Basically I’m using the stock tubes (PSVanes and I think the others are Genelex) so this may be the difference between us. In that case it may make sense for him to try some of the standard tubes perhaps? Could @Paul - PS Audio send him some - might save everyone some hassle and time?
If you are getting silence from your seating position and noise only when getting close to the speakers then we are hearing the same thing which is also what he is now hearing once he replaced the bad preamp tube. So changing tubes again to get the noise lower as the Tungsram’s are noisy in the preamp or trying the attenuators are his best options if he wants to lower the noise floor even more. He is now at what Paul and his dealer said is normal so the problem is solved and the amp is fine. Whether or not you agree with my assessment or theirs is up to you. I am using 1952 Raytheon 5814’s as I found all of the 6 and 7 volt tubes I tried (over a dozen pair) to be too noisy compared to any 12 volt tube I tried which didn’t include the included Psvane’s. So I went through my stash and found the pair that was an acceptable combination of low noise and desired sound profile.
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OK I think I must be misunderstanding then. I thought he was still hearing the hiss from the seated position.
I am using 1952 Raytheon 5814’s
Wow - where did you get these? I’m presuming they aren’t cheap.
I bought them from a member on AudioKharma that had bought a couple of dozen pairs from a military surplus supplier and wanted to sell off a few pair. These were made for the US Navy. I think I paid him $40 for them. They would be several hundred for a pair now if you could find them. They will probably last 5-7 years at a minimum in the BHK.
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You are lucky! I’m having a real job finding NOS tubes here in the UK to experiment with. Pretty much everything is either sold out or crazy expensive to the point where I"m scared to buy them just to try them out. I think for the time being I will stick with the stock ones until I can find a good source.
Try some new tubes. You will be surprised. I’ve run a few expensive NOS tubes, that were good , just not from top to bottom. I’ve used 3 sets of new production tubes that were better than any NOS I’ve tried which include Aperex 7308, and Tungsram BHK select. I got 4 sets of the Tungsrams when I bought my BHK amps from Upscale.
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I will. I’m just looking for some good dealers in the UK/Europe or if not someone who will ship to the UK. I understand that Upscale don’t do shipping outside the US for tubes.
I think you mentioned the in production tubes before. I think it may be worth making a thread purely for in production tubes that are good (as they tend to get lost in the NOS discussion).
That’s exactly what I’m saying.
For clarity, you are talking about turning up the preamp, or turning up the DAC? With the DAC the noise level should stay the same at all volumes.
You are putting words in my mouth that I have not said.
The fact remains that somebody bought a power amplifier, regardless the brand, that is not old and used to cost US$ 6k -7k and has synergetic source equipment from that same brand and is faced with audible noise and hiss. While when he used his previous power amplifier of a different brand there was no noise or hiss even with the BHK Pre connected to that previous power amplifier.
Now with the DSDAC, connected directly to the BHK 250, the output level has to be lowered by 20 dB to get “acceptably” rid of the noise. Note: in that set up the Pre was not even connected.
Whether I own this equipment or not, that reads wrong.
Anyway it’s not my problem indeed and it’s finally up to the current owner what to do with it.
I just advised to seek professional advise from the manufacturer PS Audio, or get it repaired, I don’t see what’s wrong with that.
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The problem is that much earlier in the thread before you jumped in he found out that the source of his problem was a bad preamp tube and not the amp at all. Also it has been determined long ago that the DS Sr. to amp works for some setups but not for others. Anyway the problem was resolved a long time ago.
As they say on the Battlestar Galactica reboot: “All this has happened before, and all this will happen again”
https://forum.psaudio.com/t/bhk-pre-amp-and-speaker-hiss/9838
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Yeah, there are pages and pages of reports here of BHK stuff doing odd things. Sometimes traced to hardware. Sometimes traced to installation (the gain structure, or whatever). Sometimes traced to unknown gremlins. Or whatever. The biggest revelation to me in following these discussions is Paul has now said the hiss in the BHK ecosystem is normal. So my way of thinking, if hiss is not the normal you want, look at other options. Some owners don’t mind the hiss because, despite this, at normal listening levels the BHK soundscape is acceptable to them.
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Langrex in England:
Good supplier of NOS tubes.
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I’m talking about turning up the preamp. I reduced the DAC volume to give me more fine increments on the volume control on the preamp but I’m listening at the same sound levels - it’s just that now those levels are in the 30s rather than in the teens.