Modding the BHK Preamp

I searched and didn’t see a thread dedicated to BHK Preamp modding.

The BHK Preamp has heat vents. While I was replacing the legs one day, I scrapped the vents and heard a zing. I figure it’s not a good thing when a resonant sound hits it, and it begins playing tunes.

So, my first BHK Preamp mod is… lining the vents with padded tape. The bottom side also rings and has tape applied.



Edit: I used this felt tape, though any tape of reasonable thickness should act as a damper.


Folks might be interested in some more details about the tape you used.

Jut a thought…

1 Like

Does the sound of the system differ between before and after, or have you not had a chance to evaluate?

It would be easy to listen with the vent removed as well. Perhaps someone has done this.

That’s a good idea @vee

I noticed the ring the first time I pulled to replace tubes - since no family member or pet enters my room (except by invite), I just left the vent off for now.

1 Like

This. I just added it. In theory, they’re like a hundred little tuning forks, so I just need to find the resonant frequency and play some instruments’ in that frequency.

I think it would have to resonate to create enough volume to be heard at LP.

The bottom of the BHK Pre has more zings.

1 Like

Adding tube dampers might be more effective.

I do not think we will hear the vent cover itself resonating. Instead, if the cover vibrates it passes the vibrations to the electronics potentially impacting the sound.

I did have a set of Siemens 7308 tubes that ringed when I muted/unmuted. The click from the relays caused enough movement to disturb the tubes. Tube dampers helped with those specific tubes, but they still rang to a lesser degree.

I’ll see if they still ring to the same degree with the tape.

1 Like

I’m curious about other BHK pre users who’ve experimented with aftermarket footers and their opinions thereof. I added ceramic jumbo Golden Sound DH Cones and Golden Sound Pads to my BHK 250 and there was a noticeable increase in resolution of inner detail in the uppermost treble region. Then I experimented with Golden Sound DH Cones and Nasotec VEM spike/shoe combos under the BHK preamp and haven’t discerned as noticeable an effect. That said, I’m not so neurotic and obsessive about tweaks that I spend a lot of time A/B’ing them while trying to convince myself they made a difference. The biggest positive effect aftermarket vibration control footers have had in my system was adding Stillpoint SS feet to my speakers. Remarkable improvements in resolution with that addition.

Very nice. JVCC tape also! Lol

I liked the look of MSB footers on their DACs, so I found similar ones, the Dayton Audio DSS4-BC Black Chrome Speaker Spikes and placed them underneath with double sided 3M silicone tape. I couldn’t say if they sound different, since I was going for aesthetics there. My entire audio shelf sits on GreatGRAMMAs, which I found to improve definition throughout the spectrum.

Stillpoints can make a significant improvement.

This kills those resonances. The butyl is sticky but is rather easily removed it need be.


Nice. I had the felt tape lying around from another household tweak and it worked surprisingly well. I didn’t have to put it on all vents like I thought I would. One strip on top and two on bottom middle vents dulled all the zings.

Good idea, definitely don’t cover the vents.

I popped in the 7308s and they’re not ringing when muting/unmuting or traversing volume gain stages (25, 53). The ringing was previously immediate and consistent; now they’re not there at all even with ears up against tweeter. I don’t have Herbie’s tube dampers installed.

Either the tubes miraculously stopped ringing, or the felt tape is working. I’ll give it a little more time.

1 Like

My experience as well - with PS Audio (BHK pre, 300 monos, all powerplants) and other gear. Stillpoints are not cheap, but do make an improvement.