# Modding the BHK Preamp **URL:** \ **Category:** Preamplifiers\ **Created:** [February 21, 2021, 5:58am UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067 "2021-02-21T05:58:43Z")\ **Posts on this page:** 18\ **Page:** 1
**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\ **Post date:** [February 21, 2021, 5:58am UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/1 "2021-02-21T05:58:43Z")
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. Before [https://dl.dropboxusercontent.com/s/1z12fm1okwbcwly/Video%20Feb%2020,%209%2042%2021%20PM.mov?dl=0](https://dl.dropboxusercontent.com/s/1z12fm1okwbcwly/Video%20Feb%2020,%209%2042%2021%20PM.mov?dl=0) After [https://dl.dropboxusercontent.com/s/6qlkdx57xi5ujuw/Video%20Feb%2020,%209%2045%2042%20PM.mov?dl=0](https://dl.dropboxusercontent.com/s/6qlkdx57xi5ujuw/Video%20Feb%2020,%209%2045%2042%20PM.mov?dl=0) Edit: I used this [felt tape](https://www.amazon.com/dp/B00ZBH3QIU/ref=cm_sw_r_cp_api_glt_fabc_FKH50NFBV6D87MWK4B1R?_encoding=UTF8&psc=1), though any tape of reasonable thickness should act as a damper. ---
**Author:** ![scotte1](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/scotte1/32/147_2.png) [@scotte1](https://forum.psaudio.com/u/scotte1)\ **Post date:** [February 21, 2021, 3:32pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/2 "2021-02-21T15:32:22Z")
Folks might be interested in some more details about the tape you used. Jut a thought… ---
**Author:** ![Elk](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/elk/32/1240_2.png) [@Elk](https://forum.psaudio.com/u/Elk)\ **Post date:** [February 21, 2021, 3:37pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/3 "2021-02-21T15:37:43Z")
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. ---
**Author:** ![senna1a](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/senna1a/32/46992_2.png) [@senna1a](https://forum.psaudio.com/u/senna1a)\ **Post date:** [February 21, 2021, 3:40pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/4 "2021-02-21T15:40:07Z")
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. ---
**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\ **Post date:** [February 21, 2021, 4:19pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/5 "2021-02-21T16:19:37Z")
> [@Elk](#): > > have you not had a chance to evaluate 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. ---
**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\ **Post date:** [February 21, 2021, 4:20pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/6 "2021-02-21T16:20:34Z")
> [@senna1a](#): > > I just left the vent off for now. The bottom of the BHK Pre has more zings. ---
**Author:** ![jazznut](https://avatars.discourse-cdn.com/v4/letter/j/b5e925/32.png) [@jazznut](https://forum.psaudio.com/u/jazznut)\ **Post date:** [February 21, 2021, 4:21pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/7 "2021-02-21T16:21:39Z")
Adding tube dampers might be more effective. ---
**Author:** ![Elk](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/elk/32/1240_2.png) [@Elk](https://forum.psaudio.com/u/Elk)\ **Post date:** [February 21, 2021, 4:33pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/8 "2021-02-21T16:33:29Z")
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. ---
**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\ **Post date:** [February 21, 2021, 4:36pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/9 "2021-02-21T16:36:42Z")
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. ---
**Author:** ![Photon46](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/photon46/32/142920_2.png) [@Photon46](https://forum.psaudio.com/u/Photon46)\ **Post date:** [February 21, 2021, 4:39pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/10 "2021-02-21T16:39:36Z")
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. ---
**Author:** ![paul172](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/paul172/32/290439_2.png) [@paul172](https://forum.psaudio.com/u/paul172)\ **Post date:** [February 21, 2021, 4:50pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/11 "2021-02-21T16:50:04Z")
Very nice. JVCC tape also! Lol ---
**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\ **Post date:** [February 21, 2021, 4:52pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/12 "2021-02-21T16:52:12Z")
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. ---
**Author:** ![Elk](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/elk/32/1240_2.png) [@Elk](https://forum.psaudio.com/u/Elk)\ **Post date:** [February 21, 2021, 4:54pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/13 "2021-02-21T16:54:42Z")
Stillpoints can make a significant improvement. ---
**Author:** ![brett66](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/brett66/32/92201_2.png) [@brett66](https://forum.psaudio.com/u/brett66)\ **Post date:** [February 21, 2021, 4:59pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/14 "2021-02-21T16:59:29Z")
This kills those resonances. The butyl is sticky but is rather easily removed it need be. > **[Amazon.com: Noico 80 mil 10 sqft car Sound deadening mat, Butyl Automotive Sound...](https://www.amazon.com/Noico-deadening-Automotive-Insulation-dampening/dp/B01KZ5X7KO?ref_=ast_sto_dp)** > > Buy Noico 80 mil 10 sqft car Sound deadening mat, Butyl Automotive Sound Deadener, Audio Noise Insulation and dampening: Insulation - Amazon.com ✓ FREE DELIVERY possible on eligible purchases ---
**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\ **Post date:** [February 21, 2021, 5:23pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/15 "2021-02-21T17:23:16Z")
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. ---
**Author:** ![brett66](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/brett66/32/92201_2.png) [@brett66](https://forum.psaudio.com/u/brett66)\ **Post date:** [February 21, 2021, 5:42pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/16 "2021-02-21T17:42:16Z")
Good idea, definitely don’t cover the vents. ---
**Author:** ![vee](https://sea1.discourse-cdn.com/flex015/user_avatar/forum.psaudio.com/vee/32/17567_2.png) [@vee](https://forum.psaudio.com/u/vee)\ **Post date:** [February 22, 2021, 5:21pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/17 "2021-02-22T17:21:38Z")
> [@vee](#): > > 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 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. ---
**Author:** ![jmeniche](https://avatars.discourse-cdn.com/v4/letter/j/838e76/32.png) [@jmeniche](https://forum.psaudio.com/u/jmeniche)\ **Post date:** [February 22, 2021, 8:31pm UTC](https://forum.psaudio.com/t/modding-the-bhk-preamp/22067/18 "2021-02-22T20:31:31Z")
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.