Isolation tweaks

[saildoctor]

I'm laughing because just yesterday I made the observation "everything works better with lead in it". 

[4krow]

Ok, that does it, it just so happens that I bought a bunch of lead sheets. They are thin and small, just the thing to wrap around a tube. Here goes nothin'

[herbelin]

Lead is not a very good damping material for vacuum tubes. Lead has a definite and annoying characteristic twang in the upper mids and the more massive the lead is, the more it will impose its sonic character into the music, and lacks the contra-vibrational energies to combat a lot of the very high-frequency, acute vibration that causes a lot of glare in the music.

Vinyl coating the lead will undoubtedly diminish the lead's detrimental character, but vinyl itself is not a great damping material either. With a vinyl-coated lead ring, you'll have basically a mass-loading weight, which does not provide a whole solution to micro-vibration damping and microphonics. 300B tubes usually don't get particularly hot, and vinyl might hold up for the short term, but surely will not hold up to hotter-running bottle-shaped tubes and other hot-running power or rectifier tubes.

Herbie's Audio Lab's vacuum tube dampers do not rely on mass. With their vibration-absorbing and dissipating C-rings, less mass is most beneficial for rapid vibratational energy dissipation and sonic neutrality. Mildly tempered titanium is ideal for this.

In regard to a previous post, Tenderfoot isolation feet are not similar to Sorbothane, nitrile rubbers, Isopods, etc. These materials, especially Sorbothane, provide a sonic trade-off--you get some vibration absorption but at the same time some loss of linearity due to resonance and reverberation being introduced into the vibrational environment. These materials provide a mid-fi tweak at best, a system contaminant at worst.

Tenderfoot isolation feet are a silicone-based, proprietary material formulated specifically to deal with the vibrational environment affecting home audio, not just a general-purpose manufacturing supply material like Sorbothane.

To bring out more of the best inherent potential of your gear, including Bottlehead products, you want to employ accessories and tweaks that provide sonic improvements only, not trade-offs.

DocB: If you would like to audition any of Herbie's Audio Lab isolation products, I'll be happy to comply. Just shoot me an e-mail or message with your request.

Steve Herbelin
Herbie's Audio Lab

[4krow]

Steve,
  Many thanks for the info. There is a sea of tweeks and ideas out there, but no promises. I wasn't aware of the shortcomings of Sorbothane. Too bad, it's readily available and easy to use. As far as damping sheets do have some advice? I'm all ears.

[debk]

I just ordered a set of the tenderfeet and will let everyone know my impression when I gt them

Deb

[herbelin]

4krow: Herbie's Audio Lab has a variety of damping sheets that are effective as a decoupling/isolation interface for many audio applications. More info here: http://herbiesaudiolab.net/gb.htm#gasket [nofollow]

To clarify an earlier post a bit, Sorbothane tends to cause a loss of linearity in the audible sonic music reproduction. Sometimes bloops and/or valleys in the bass, emphasis or attenuation in some of the higher frequencies. A "linear" sound reproduction would be faithful to the source material.

Steve
Herbie's Audio Lab

[4krow]

Steve,
  I have looked at your site, and I have also heard from many people about your tube dampeners. Given that the 3S4 tube is very microphonic, I opted to purchase the tube dampeners that you offer. If there is a tell tale tube out there, it must be the 3S4. This will be greatly appreciated if it works like it should. More to coma about that. In the meantime, I will remove the Sorbothane rig that is on each tube.

[corndog71]

I use Herbie's Ultrasonic SS Tube dampers for my Ultimate Quickie and think they do help with microphonics.  One discrepancy though was that the rings were slightly too big and I had to bend them a bit to get them snug.  It wasn't as easy as it sounds.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi576.photobucket.com%2Falbums%2Fss207%2Fcorndog642%2FBottlehead%2520Quickie%2FIMG_6781_zpsea11e3b9.jpg&hash=ee9559a73dae99b92fc83ee60c0b9eb8030be700)

[herbelin]

Hi, Rob. As indicated on our website, 7-pin miniature tubes like 3S4 use a size "7" damping instrument. In the pic, it looks like you've got a slightly larger UltraSonic SS-9 (appropriate for 9-pin miniature tubes) re-sized to fit the small 3S4 tube. I think maybe we sent you the wrong size. Looks like you've got a good fit though, and everything should work very well.

BTW, It's a lot easier to bend the titanium C-ring to a larger diameter than it is to bend it smaller.

Steve
Herbie's Audio Lab

[coca]

Re the sticky isolaters, try some of those coasters that you usually find in bars under them, that should take care of the marks on the furniture. Also how about sitting the whole unit on top of a small inner tube. If that works, a plinth could be made to surround the tube.

Bernie.

[johnsonad]

Some personal observations on isolation with my BeePre.  It has the 1.25" sorbathane half's under the base to start with and the small rings under the 300B's.  Today I received the Bel Art lead weights that Dan recommended.  Previously I had been using some of Herbies rings on the 300B's.  With the BeeQuiet, I hear ringing through the speakers with each volume change.  I used this as the mechanically induced microphany I was trying to control.  This was by ear with my 100 dB sensitive speakers in a quiet room with no source playing. 

First without anything on the tubes I get a moderate sustained ring through the speakers with each change on the volume.  Next with the Herbies the ring and decay was reduced from having nothing at all.  Next was with the lead weights and this significantly reduced the ring and decay, much more so than with the rings alone and to a very low level.  Lastly I tried with both weight and ring and I heard no difference from with the weights alone.

I'll listen to some familiar recordings today and post if I hear any difference with play and if I can find the time, I'll measure the ring on my scope to give some hard numbers to what I'm hearing

Great find Dan and thank you for posting about them! 

[mp9]

- Re: sticky isolators. I've been testing the Urethane Coated Hemispheres fora little  over a month now under my tube amp^, (using higher 1.25"/50A instead of 1.24"/30A, the amp weights more then a Bee).
So far the urthane coated hemi's have been great as far as not leaving sticky residue etc on surfaces. Can't comment on what they're supposed to do as my amp wasn't having any trouble prior, used it to emulate the heat aspect of the Bee as i've yet to build mine^.

I had difficulty finding a supplier for the Urethane Coated Hemi's. Let me know if anyone is interested in doing a group buy from Sorbothane Inc.?

Sorbothane HEMISPHERE with Urethane Coating part#0510124-30-10, 1.25"/30A rated load 2-4lbs.

http://www.sorbothane.com/blog/wp-content/uploads/2012/12/11-26-12-Sorbothane_SPG_11.2012_v4.pdf
[/quote]

- johnsonad, thanks for posting your tube damper findings.


^my Bee build is on hold for chrome plating, i'm told spring is their busiest time of year.

[4krow]

Hwy, thanks for the Sorbothane info. There are a lot of uses for this product(I walk on one everyday). One of these days, I will get the sorbo mallet. Also, did you notice that some of the hemispheres have felt on the bottom?  hmmmm

[Doc B.]

Thanks Aaron. I guess sometimes that physics degree I got a zillion years ago pays off. Maybe part of what is happening is the added mass of the lead ring helps the tube base make better contact with the silicone ring under it. So you have not only the new constrained layer damping effect of the lead and vinyl on top, but also the one created by the silicone ring sandwiched between the tube base and socket is made more effective. Neither material is super squishy, but they do have some damping effect.

There was a day when I could have written a multi-page solution of the sprung masses, with error analysis. But that was a loooong time ago. And now days I have PJ and PB to be my brain.

I do share Steve's concern that the vinyl on the ring might not hold up to a 300B running full zoot in an amp. I've had them on the much cooler running BeePre 300Bs now for several weeks, running about 8 or 9 hours a day with no ill effects. The rings don't get very hot, they lift right off the tube and the vinyl shows no deformation. But that's at 10W dissipation, whereas the Paramount 300Bs run at about 24W. And for that matter I don't see any real need to do this as I have not heard any microphony from Paramount 300Bs. So consider this a strong recommendation not to try the rings on Paramounts.

[debk]

I have no problems wit the rings and heat.  I think the rings are a simple elegant isolation tweak that works incredibly well.

Even with my dogs running around in front of my system there is no issues with microphonics!

Deb