BHK preamp emits high-pitched whine when warm

The fact that it’s correlated with the tubes makes me think it is tube related. Specially if it wasn’t happening with the previous tubes that had 2500hrs on them. Sending it in with the Genalex is the only sure way to tell though. Our team will be able to measure it with those tubes to make sure everything is OK.

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I love my BHK stack too! Since getting the BHKs, I enjoy it a little too much and my kids would ask me to down the music! LOL!

Actually Serhan I now remember that when I first got the Pre and was getting accustomed to the remote, I would accidentally hit “Off” button by mistake. If I immediately turned it on again the Pre would whine. I had to power it down completely then reverse the sequence to power on again. Of course the problem never recurred once I got used to the buttons on the remote. I leave it on standby the vast majority of the time as recommended when not listening to music.

I do have some other tubes on hand that I found tucked away in a drawer. Including another set of 12AU7 Genalex’s from Upscale and the new Psvane 12AU7S from Viva. I still have the original ones on hand too. I will do some tube swaps in the coming days and report back.

It would be great to not spend several hundred bucks to ship the Pre back to Boulder. Oddly, the RMA instructions said to send it back only with the original tubes which is a bit puzzling to me as it would make replicating the problem harder. I have no problem sending in the “whiny” tubes.

Haha, the remote for the BHK pre and the DS DAC is unusual. First, the “Off” button is large, and it’s right in between the “on” button and the “screen off” button. So, I do turn it off in error too. Also, volume control for the pre is counter-intuitive. Almost every remote I owned had the volume button(s) on the left to be easily operated by thumb. Anyway, like you I try to pay attention, but I still turn it off by mistake every now and then. Else, my tubes have been running perfectly and the pre sounds better than I ever hoped for. Before sending it, I would make sure tubes and mains voltage are good.

I recently bought a phono preamp that weighs 25kg boxed. Left channel died after playing 3 LPs. I got so frustrated, but luckily the dealer will organize a FedEx pickup and deliver a new one. I guess I am lucky it failed on day one. Had it failed a year later, shipping would be my cost.

Hey all:

In order to determine if the problem lies with the Genalex 12AU7 or the BHK Pre. I decided to run a little experiment with different sets of 12AU7s. My plans were delayed by a historic winter storm resulting in widespread power outages in my state. Even though we weathered the storm just fine, I did not feel it was the right time to be messing with the rig. So I took my system offline for a week until the power and water situation stabilized in the city. Anyway here are the tube types used:

  1. Genalex 12AU7 #1 (Upscale, Kevin’s stash)
  2. Genalex 12AU7 #2 (Upsacle, Kevin’s stash)
  3. Psvane 12AU7 Art Series (Viva)
  4. RAM Tubeworks 12AU7C (Tubeaudiostore, SLN grade)
  5. NOS GE 6189W/12AU7 (Upscale, Kevin’s stash)

These are the steps:
a) BHK Pre fully powered off (rear switch off) for 8-10 hrs.
b) Tubes installed and the rear switch was turned on.
c) After ~ 1 minute, the Pre was turned on via the front panel switch.
d) Played music from my Holoaudio Spring 2 KTE for ~3 hrs, listening via Focal Clears.
e) Placed the Pre on standby mode overnight.
f) Turned on the Pre next morning via the front panel switch to see if it whines. Front panel displays a shorter countdown.

And here is what I found:

  1. Genalex 12AU7 #1 – Step c – 1 second chirp then silence. Step f – immediate whine when Pre turn on from standby mode which does not go away.
  2. Genalex 12AU7 #2 - Step c – 1 second chirp then silence. Step f – immediate whine when Pre turn on from standby mode which does not go away.
  3. Psvane 12AU7 Art Series – Step c – no unusual sounds. Step f – no whine
  4. RAM Tubeworks 12AU7C – Step c – no unusual sounds. Step f – no whine
  5. NOS GE 6189W/12AU7 – Step c – no unusual sounds. Step f – no whine

From a cold start the BHK has a longer count down vs. taking it out of standby. I found if a the tube type chirps in step c, it would whine when taken out of standby in step f. At the same time I feel it’s pretty unlikely that I was sent two bad pairs of Genalex’s as they were purchased >6 mon apart.

One could surmise that that there is something about the Genalex’s that causes the whining. It could be unmasking a problem with the BHK Pre or maybe there is simply a compatibility issue with this tube brand. What do you all think? Do you think there something wrong with the Pre or should I just simply avoid Genalex’s ?

I made some videos of the whine but I cannot figure out how to upload them here as the forum only takes image files not .mov files.

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A lot of people here have used the Genalex tubes including myself with no issues so I don’t think it is the brand of tube. You say the two sets were purchased six months apart but they were still from the same source and could have been from the same shipment. The fact that three other sets from three other manufacturers work fine don’t point towards a preamp problem but rather a tube issue. If you are determined to try the Genalex tubes then I would try another source with matched triodes and the ability to send them back if they won’t work. There are still several reputable sources of NOS tubes of the 12AU7 variety that are considerably cheaper than Kevin.

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A friend has the same issue with whining from his BHK. It happens exactly as described by Serhan.
If he turns it off and then turns it back on–with the rear power switch–too soon, it whines. If he waits a few minutes before turning back on, no issue.

dawkinsj

I slept on these observations last night and I agree. I forget that Upscale unlike Home Depot where the inventory turns over every few days to weeks. His inventory of Genalex 12AU7’s probably don’t turn over very fast.

It makes sense that it’s not an issue with the Pre because 3 other types of 12AU7 did not reproduce the problem. I did email these observations to PS Audio support with video to get their input. Its going to cost $400-500 (FedEx with insurance) to send the Pre back for warranty inspection so would like to avoid it if I can.

Although I have a few NOS tube sets on hand, I want to stick to current production tubes and save the more expensive NOS for when I am one of those tube rolling moods (not very often as the Pre sounds fantastic!).

I would like to know where the forum members get their current production 12AU7’s? A google search of 12AU7’s shows Tubedepot and thetubestore. Any experiences with these places? Of course I could always get it from PS Audio but they offer Psvane.

Mine came from the Tube Store but others have had good luck with Viva. Never bought preamp tubes from Tube Depot only power tubes but they have been around a good while.

Hello all:

I am this posting update in hopes that it might help others who are experiencing whining BHK Pre issues. I sent the Pre back the PS Audio for warranty service and the process took a little over 3 weeks to resolve partly because the RMA policy required that the unit be returned with only stock tubes installed and no other extras allowed.

Problem - The picture below is a screenshot from my frequency analyzer phone app that illustrates the problem. This only occurs with Genalex Gold Lion 12AU7 tubes and not with other brands including NOS and current production 12AU7s. The sound was emanating from the Pre itself as if there was a transducer inside producing the noise.

.

Cause - With original tubes in place, the problem was not reproducible. I sent them some videos that illustrated the problem. It was escalated to the engineering dept where Darren was able to reproduce the issue with his personal set of Gold Lion 12AU7s. The etiology was “…some characteristic about the Gold Lions heaters caused the heater power supply to oscillate… The reason your unit oscillated is likely due to the small variation in regulators from the semiconductor manufacturer that produces the IC.”

It was not explicitly stated but I assume that the regulator in question was replaced. I have the Pre back now and can verify that the whine no longer occurs with Gold Lions, stock Psvanes, and current production Telefuken (JJ) 12AU7s!!

The PS Audio team have demonstrated great professionalism throughout this process and I could not be more please with the customer support I received!! :100: :clap:

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An intriguing story with a happy ending.

Great bit of detective work by Darren.

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I have the same issue with the Genalex 12au7 tubes. Not with any other manufacturers tubes.

In my case, it happens only if I turn the pre off, and back on within 10 - 15 minutes. I had this issue with both Genalex & Psvane. To resolve, I normally wait for 15 minutes before restarting, and that’s it. The whine does not affect performance or life of the tube.

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Serhan,
I never did the extensive investigation that you did. Once I became aware of the whine ( high frequency oscillation) I just changed out the tubes. I cannot imagine that the oscillation is good for the heater regulators in the preamp.

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Indeed sixpack 1. I initially talked myself out of sending it in since it only occurred with Gold Lions. But I eventually got concerned about potential catastrophe if I ignored the warning signs. Ironically, what tipped the scales for me was listening to Ducan and Darren’s podcast about noise. Darren cited an example about certain electronic components that when they malfunction, become physical transducers.

Since the Pre was still under warranty, I sent it back for inspection. The only cost was shipping the unit back to PS Audio. Be aware that their RMA process required that the unit be returned with the only Psvane 12AU7s and of course the issue won’t be reproduced right off the bat. But now having worked through this issue once, they should be able to resolve yours faster. The person who handled the RMA for me was Scott Schroeder, the technician was Rob Bowdish who I credit with escalating the issue to Darren. Their customer service team gets 5-stars from me!

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My preamp has recently been back from repair. They installed a new mainboard. This was for an issue which ended up being tubes in the BHK 250. It is no longer in warranty unless they give a 1 year warranty for the service. It would be costly to send it in again. I have not had the issue with any other tubes in the preamp. I should be safe.

i am auditioning the BHK preamp. coupled with the directstream dac, perfectwave SACD transport, BHK 250, and P15. so i guess you could say i am ALL IN! lol.

using stock 12au7s. has anyone resolved the high-pitched whine produced by the BHK pre amp.

As reported above, my problem was solved when I sent my pre-amp back to PS Audio and they rebuilt it. No more whine for a couple of years now. I don’t think it is inevitable that there will be a whine with the original tubes or with any others that are not defective. Currently running Tungsram 7DJ8’s but worked fine with original tubes as well. If you bought one and experienced this problem I would try to get it fixed immediately while the warranty is fresh.

Well, it’s important to keep in mind how many we have shipped and sold compared to how many have had this issue. People tend to focus on the issues here. If the many many people that have received one all logged in here and mentioned that their pre showed up in perfect working order, you’d have a much different perspective.

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And many, many hours of reading ahead of you. :slight_smile:

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Interesting information here. I’ve had similar issues. I “upgraded” from the PSvane to the Genalex (Upscale, Kemin’s stash). I only had the issue with 1 of the Genalex tubes. I just got a replacement last week and I have a slight buzz when turned on, it quickly goes away. From my experience, I was able to solve the issue by finding the right tubes. Having done all of this, My biggest learning is probably that I should have left the Psvane in place.