I had the thumping sound with the stock tubes with the pre out of the box. PSA quickly shipped out replacement tubes. No issues are that. I also had the thumping sound with a pair of tubes form Upscale, which is in the process of being replaced. Kevin form Upscale is a super guy. I would deal with him again, no pun intended.
PSA customer service is AMAZING! Truly one of the best in the industry. I am blown away with my BHK signature preamp!! BHK 250 amp! DSD dac also!! I am looking forward to a DS transport this fall.
PSA customer service truly is a cut above. I echo your comment 100%. When I wanted to take advantage of the trade-in program to purchase my pre, the folks at PSA personally called my local dealer to arrange for the trade. My dealer had a unit in the color I wanted in stock and PSA’s customer service folks wanted my trade to go as quickly and smoothly as possible.
Best experience by far in 30 years as a serious high end audiophile. Kudos to the team at PS Audio.
PSA customer service truly is a cut above. I echo your comment 100%. When I wanted to take advantage of the trade-in program to purchase my pre, the folks at PSA personally called my local dealer to arrange for the trade. My dealer had a unit in the color I wanted in stock and PSA’s customer service folks wanted my trade to go as quickly and smoothly as possible.
Best experience by far in 30 years as a serious high end audiophile. Kudos to the team at PS Audio.
Thanks! We are all proud of our extraordinary team.
I replaced my tubes today with 7DJ8’s, changed both filament and bias jumpers, but I hear a low level pulsing sound all the time and a static/clicking when adjusting volume. Hear in both channels, Sq is is on bright side. Can’t be right. Anyone any ideas, defective tube ?
I had the same problem with 3 of the 4 BHK select tubes from Upscale Audio Kevin shipped me. I returned them, waiting to hear back from Kevin on the test of them. Funny thing is, in the BHK amp they were fine???
You are the third to post about this pulsing sound, I did not get a full refund btw. But could be related to the Pre as a second set I got from another source were noisy and took out the fuse.
For what it’s worth, I’m noting the hiss/static issue I experienced with my BHK Pre below. Given the adjectives used above to describe these issues - thumping, pulsing, etc, tough to tell if it’s on point, but here it is anyway.
When I added the BHK Pre to my system switching out the previous preamp, I noticed a distinct level of hiss coming from both speakers that was not there with the previous component. Same level of hiss from both, present when music was playing or not, and at a constant level independent of volume. As Paul previously noted, there is some to be expected. Nonetheless, I thought the level to be a bit high, as I heard it from my listening position (10ft/3m). The hiss was present when both the stock tubes and the Tungsram 7DJ8s from Upscale Audio were in the system.
In addition to the general hiss level, there is a distinct graininess/pulsating static/hiss coming from the right speaker, fed by the (RED) XLR output. It is an odd pulsating static that emanates from all drivers on that particular speaker. Further testing confirmed the offending XLR output, as swamping the connections shifted the issue to the other speaker. Testing also revealed that hiss to be present without any other sources connected to the BHK Pre also.
Also possibly worth mentioning, although I am not sure it is relevant to the hiss problems. Using the BHK Pre in my system, I reached a comfortably loud volume level at setting of 30 (should have measured it with my SPL meter but did not). Given the theoretical range of 100, I found that notable. Not sure what others have experienced, as this is undoubtedly system dependent.
System note: IC cabling is balanced throughout (XLR); PSA DMP and DS DAC are the upstream components.
I’ve been working with the always excellent PSA customer service team to troubleshoot/resolve the issue, and had sent the unit back for a check-up.
JM said
Using the BHK Pre in my system, I reached a comfortably loud volume level at setting of 30 . . . Given the theoretical range of 100, I found that notable. Not sure what others have experienced, as this is undoubtedly system dependent.
System note: IC cabling is balanced throughout (XLR); PSA DMP and DS DAC are the upstream components.
With most recordings, I run the volume in the 30-34 range on the BHK pre. With some recordings that have a very large dynamic range (i.e. are uncompressed) I can go as high as 50 or 55. Last night for instance I was playing the LSO/Haitink version of Berlioz’s Symphonie fantastique (DSD) at this level. But given that unity gain on the BHK is 70, IIRC, there’s still a lot of unused headroom here. Fortunately I have no hiss issues. (There is a little hiss audible if I put my ear right next to the tweeter with no music playing, but I think that’s normal with tubes and it’s not apparent from the listening position.)
If I change speakers at some point while keeping the BHK pieces, I wonder if I should look for something less efficient than my present ones that have a rating of 89 or 90.
And, of course, you lower the volume a few clicks using XLR interconnects compared with RCAs.
Please update us on your discussion with PS Audio customer service regarding the general hiss level. I have the exact same issue, I can hear it from the listening position. Thanks.
Can anyone tell me the advantage to running a 6922 vs a 12au7? As I wait for Kevin to send replacements I am running a pair of JJ 12au7 tubes. I like them a bit better than the Lion’s. I feel they have more open and more air to them and they are only 20 bucks a pair!
A few of us on the board have compared 6//7/12 series tubes in our BHK preamps - including the 12AU7. See posts 95, 105 and 113.
Again if it helps other BHK owners, I’m now using NOS Telefunken 6922s (1968 production). So I’ve tried the stock Psvane 12AU7s, NOS Telefunken 12AU7s, Siemens 7308s, Siemens 6922s and … now … Telefunken 6922s. I continue to prefer 6922s and 7308s over 12AU7s of any brand or vintage. I like 6922s and 7308s for different reasons. The 7308s are super for voice and jazz, they have a juicy midrange that reaches out and grabs me. Both NOS Siemens tube types I’ve experimented with have that same tonal trait and I’m a sucker for it. The Telefunken 6922s are more neutral and more laid back. I recently changed a component in my digital front end and the Telefunkens are an even better match for my system than the Siemens 6922/7308s. I intend to hang on to my Siemens tubes - they’re beauties.
I’ve never experienced pulsing or noise problems with any of these tube types, brands, vintages, btw. The bulk of my experience has been with the NOS 6922s and 7308s and they have been spooky silent performers in my system.
Hi owlsalum, Thanks for your post #130. Among all the tubes you tried in your BHK preamp, is there a pair which noticeably lowered the background noise (the noise can be heard from the speaker, without music playing, not due to ground loop, not due to any other equipment such as BHK amp which is pretty silent)? I would like to try a different set of tubes, two goals, one to lower the background noise, two to enhance the sound (not to change the overall character of the BHK preamp sound). For the second goal, do I need to change the tubes in the BHK amp in order to hear any improvement? Multiple posts here mentioned Tungstram PCC887DJ8. Thanks for the advice.
What is the input sensitivity of your amp? I had EMO’s with 32 DB and they were not good with any tube preamps. I sold them off. I use a EMO XPR-2 with 28 DB, far better.
I had the same problem with 3 of the 4 BHK select tubes from Upscale Audio Kevin shipped me. I returned them, waiting to hear back from Kevin on the test of them. Funny thing is, in the BHK amp they were fine???
OK, I think, at least with my BHK pre I figured out some of the pulsing noise. If I use ANY of the Tungsram PCC88 tubes I bought form Upscale with the jumper in the 5ma setting I get the noise. In the stock 4ma, it’s all good!
I did have pulsing with stock tubes, PSA quickly replaced. Awesome Customer Service!! I did have a little bit of noise ( hiss ) but not alot. At 13ft from my speakers I could not hear it, even with the swapped tubes in 4MA. Tell you what, I think I like the JJ 12AU7 so far the best. I only have the cheap red lettered ones too. I may order the gold pin JJ 12AU7 to try. I liked the air of the JJ so far the best!
The question had been asked by darrenv1070 a short while ago about using a 12AX7 in the preamp. Well, that tube has very different characteristics than the 6922 type such that it decidedly won’t work in the preamp tube stage. I have attached two plate characteristic curves for both tube types with the load lines for 10K plate load resistors used and with the 120v plate supply voltage. The 12AX7 is on the left and the 6922 is on the right below. Now for the 6922, the red circle is about where the operating current of 5 mA sits and is the operating point. the grid bias is a negative value and all is good. Now for the a2AX7 tube, which would be great for higher supply voltages and higher values of plate load resistance, for the operating conditions in the preamp circuit, for a 4 mA operating point (because that is visible on the graph) we see that the operating point would be way into the positive grid voltage region to get the 4 mA. This means that the input impedance to the grid would now be low due to grid current flowing and tube would be VERY saturated and non operational as an amplifier in the preamp circuit
I hope that explains it - for those that could understand what I said EXTRA ANNOYING NOTE, THE 12AX7 CAME OUT ON TOP AND THE 6922 ON THE BOTTOM.
OK, so these are the tubes I have tried so far: JJ ECC802s ( gold pin ), JJ E88CC ( gold pin ), Philips PCC88/7DJ8, Tungsram PCC88/7DJ8 ( BHK selects ), and the JJ-ECC82.
My preamp for some reason ( maybe environment ) will not work with 6922 tubes? I get noise, and often a low level pulsing. I have tried current jumper, and different power cords. No clue why.
I will say, believe it or not the BEST tube by far is the JJ-ECC82…and these are 10 bucks each!
Can you explain why myself and several others have had pulsing sound or worse yet distortion or cracking sound when trying to use 6922 tubes? I have tried several tubes, all with ill results. If I try to use any 6 volt tube in my BHK preamp it turns out bad. I have moved 12V jumper to 6, and have tried the 4MA and 5MA positions. None of which see, to keep preamp stable. I am using PSA P-5 to power equipment.
EXTRA ANNOYING NOTE, THE 12AX7 CAME OUT ON TOP AND THE 6922 ON THE BOTTOM.
