Isolation tweaks

[Doc B.]

If you look at the published dimensions the 1/2 lb. ring is the one that will fit over the top of the EH 300B we supply with the kits. If you use other brands of shouldered tubes or a globe shaped tube - which I do not necessarily recommend because they can be more microphonic than the shouldered tubes - or you wish to try this on something other than a 300B you may wish to evaluate the published dimensions of the other ring sizes. I suspect the 1/2 lb ring would fit most shouldered and globe style 300Bs but I have not measured any but the EHs and TJ globes.

[4krow]

Whenever I go to the hardware store, the clerks know just to let me be. What I am looking for they have never heard of, and what I am using it for they have never thought of. Such is the case here. But I still wonder if there might be a way to make your own. If it's anything like coffee, I am better to just pay the $3 and let someone else do it. This does seem to be a really good idea. Maybe I can use truck bedliner spray on tubes   Heh heh

[Grainger49]

Dan,

You are going to make me post a picture of my Lava Lamp.  That was my Birthday present to me last year.  The Eros was the year before.  Quite a difference!

Does the same ring go around a 2A3? 

Thanks,

[Doc B.]

Here they are on Ken Rad 2A3s in the Stereomour built to demo our awesome new Bottlehead/Orca system. I have not listened to this setup. And I will say that I don't really notice a microphony issue with either 300Bs or 2A3s in amplifiers, with the occasional exception of globe style tubes. I also don't know if the increased dissipation of a 300B in an amp would create a potential heat issue for the vinyl or not. Remember that we are running the 300B very gently in the BeePre, only about 10W of plate dissipation.

[mp9]

Does the same ring go around a 2A3? 

I measured a few ST shape tubes. 1/2Lb i.d. ring fits my RCA and Sylvania 2A3's. Shug 2A3-Z could fit either the 1/2Lb  or 1LB. JJ 2A3-40 would require the 1Lb i.d.

Only 300B's on hand which i plan to use are Sophia Princess, they can fit either 1/2Lb or 1Lb ring with possibly only one smaller contact point using the heavier 1Lb 2" i.d. vs two points of contact with the 1/2LB 1.7" i.d.

I don't know how or if the ring weight (2X) or surface area contact would affect the intended purpose? Compelled to ask, given i was wrong about upping the sorbothane hemisphere's size:\

[4krow]

Didn't the Coneheads use rings too?

[Doc B.]

I can't answer to what the effect will be if you change the weight of the ring, other than to say you may need to re-evaluate what sorbothane hemispheres you use since the overall weight of the preamp will change. Sometimes the data comes out in a more timely and useful fashion if more than one person does the experiment.

[mp9]

Note that the PDF says "underloading will result in poor isolation". The preamp weighs about 12.4 lbs (now 13.4 with my new tube dampers), well within the spec for four 1-1/4" hemispheres, but too light for the 1-1/2" ones.

 
Rated load is 2-4Lbs (1.25"), and 4-7Lbs (1.5"), so 1.25" hemispheres should be good with either size ring.

Unless i read otherwise, i'll get the 1.25" hemi's and hold off on ordering rings 'till i hear the BP without them.

I'm thinking if the .5Lb ring is working for you then why possibly stress the tube with more weight? Conversely, the larger 1Lb ring/one contact point when fitted on the Sophia tube may trap less heat allowing the tube to maintain a more constant temp?? IDK???

Again this is all just thinking out loud, 300B's are expensive tubes for me to be tweaking with.

[jdm]

Dan,

What differences do you hear between the EH and TJ tubes in the BeePre?

Jim

[Jim R.]

Dan,

Nice find!  When you do get to hear the stereomour with these rings, if there is any noticeable difference with the rings, could you let us know?

-- Jim

[Doc B.]

@jdm - TJs sound a little better to me, however that one in the photo is old and worn out so it actually sounds worse. And I found them to be fairly microphonic in the preamp application.

@Jim R. - I hope that we will have the Orca setup going next week, but it might not be all together until we get back from Axpona. I will report if I hear a difference with the dampers on the Stereomour tubes.

[johnsonad]

I ordered a pair of these a couple of weeks ago and only today received the shipping notice. It seems we depleted their stock

[Downhome Upstate]

I've had good results with Herbie's Audio Lab isolation and damping products, including Tenderfeet (the Tendersoft variety) under the Stereomour. Very affordable, and with a 90 day guaranty.

[Doc B.]

FWIW looking at the specs the Tenderfeet seem pretty much like the Sorbothane hemispheres.

The tube dampers look to be considerably less massive than the lead rings, so it would be difficult to guess how they compare.

If Herbie wants to loan us some samples for comparison I would be happy to post my observations.

[debk]

The lead rings work great!  They are inexpensive and I highly recommend them for the BreePre

Deb