Isolation tables/stands for valve monoblocks?

[dynamic turtle]

Hi folks,

Can anyone recommend me some isolation tables/stands for valve monoblocks? Given all the dust & microphony issues with them being on the floor next to the speakers, I think its worthwhile investing in a pair.

Any ideas? The amps are 60cm long and 30cm wide.

Budget? Up to £200 I suppose...

Cheers,
DT

[alexs2]

Going to be difficult for that sort of money,as it rules out most of the upmarket things like Finite Element and Stillpoints etc etc,but one thing you can try is a slab of either granite,or a paving slab,and then mount the amps on top of something like Foculpods or similar on top of that.

It's not pretty,but it is effective and cheap,and probably not a great deal worse than some of the very expensive options available,none of which will remove airborne vibrations as a source of microphony.

On a side note,there was an article in last month's HiFiNews looking at microphony in general,related to tubes,and as expected,small signal tubes are probably the worst overall,and even then,some of those are known to be far worse than others.

Try and keep the amps a suitable distance from the speakers if possible,but I have a similar situation to yours,in that the amps are quite close to the ESLs,on 1 metre leads.

[dynamic turtle]

granite slabs & paving stones aren't exactly going to enhance the domestic harmony of the living room (which already looks like a branch of Sevenoaks!). There's also very limited space and I'd ideally like something with a footprint the same size as the amp.

Although the tubes have been vibration-damped to death, the CV1988 is occasionally microphonic at loud volumes, hence the thought. I also want to get them off the floor to stop dust getting into them...

DT

[alexs2]

Well...there's the problem....there arent many decent systems at that price that will also offer adequate vibration isolation into the bargain,although you could try scouring the used and exdem outlets for something.

Had you mentioned space issues and aesthetics,I probably wouldnt have suggested a paving slab.

You could try Choice Hifi( www.choicehifi.com ),who often have used stands like Mana(if you believe in them,that is) which may fit the bill for you.
Mana,whilst highly regarded,seem to have ceased trading recently,so there may be a few at decent prices.

[deaf cat]

Just a thought, I know very little about this damping and vibs business but what about one of those solidish steel type shelf bracket things that bolts to the brick wall, which turntables sometimes sit on.......?

[Ianfromnotts]

I use marble cut offs from the centre of fireplaces cut to the size of the amps with cones underneath when I have amps on the floor. Not sure it sounds any better but keeps the airflowing etc

Have you thought about rolling your own? I made one for my receiver and CDP because they are sitting on a chest of drawers until I can do something different.

Two peices of MDF cut to size. Sandwich 5 peices of sticky tack from Staples in between. Cut two superballs in half for feet. Works like a charm. For carpet, use spikes instead of superballs. Cost $15, plus $3 for flat black spray paint.

[Knightshade]

Due to it's construction, mdf is not the best choice for isolation, vibration is transmitted rather well by it. Replace the MDF with even lowly pine and you'll notice a difference.

[dynamic turtle]

Originally Posted by ClemmonsHoo

Have you thought about rolling your own?

Well, seeing as Kenny Everett based his DIY character on yours truly, I'll be leaving that option well alone

There is a guy on eBay I should contact actually - i've bought several granite slabs off him in the past that I'm really happy with. Maybe he can make me some half-width ones...

DT

First things first - are you actually having a problem? If so, is it airborne or structural?

The thing is, a lot of people place their amps on slabs and then leave them right in the firing line of their speakers. Try rapping a lightbulb with your finger and I'm sure you'll see the effect bass notes can have at short range.

Also, be careful about the difference between 'coupling to' and 'decoupling from' solid surfaces. Some amps react better to floating on a solid surface, some prefer being solidly fastened to it (it's all about which resonant frequency does the least harm).

Personally, if you're worried about the close proximity of the speakers and vibrations through the floor, wall mounting the amps (using something like a turntable shelf) makes good sense.

[dynamic turtle]

The tubes are occasionally microphonic at higher volumes and at certain frequencies. It doesn't spoil the listening pleasure as its infrequent and generally not unpleasant when it does happen!

Wall mounting is not an option - this is rented accomodation and shelves would looks very awkward indeed!

DT

If you've damped the tubes (I assume you have from your previous post, and really only the input tubes will be susceptible), there's not much point in using any sort of stand if they are going to be in close proximity to the speakers.

Hence the wall-mounting suggestion. Alternatives I suppose are:

1) Put them behind the speakers where there is less airborne bass (doesn't cure any structural stuff coming through the floor)

2) Enclose them in a heavily-built structure (allowing adequate ventilation of course)

I suspect Alexs2 won't suffer the problem to the same degree - the ESL's don't exactly produce thunderous bass.

[shahedz]

excuse my ignorance but what is microphonics?

What About Microphony?

If you strike any tube it will emit a slight "tink" or "ring" through the loudspeaker. This is called microphony. In extreme cases this may become excessive, and the tube should be replaced. Rough handling, poor chassis construction, and even air shipping can encourage microphony.


Courtesy of vac-amps.com

[dynamic turtle]

Originally Posted by Abootnoo

If you've damped the tubes (I assume you have from your previous post, and really only the input tubes will be susceptible), there's not much point in using any sort of stand if they are going to be in close proximity to the speakers.

Hence the wall-mounting suggestion. Alternatives I suppose are:

1) Put them behind the speakers where there is less airborne bass (doesn't cure any structural stuff coming through the floor)

2) Enclose them in a heavily-built structure (allowing adequate ventilation of course)

I suspect Alexs2 won't suffer the problem to the same degree - the ESL's don't exactly produce thunderous bass.

Yep, all heavily damped with two silicone rings per singal tube. The 845's aren't microphonic and run too hot for silicone!

The speakers are rear-ported so placing them behind may not solve the problem. Also, its a suspended floor, which doesn;t help either.

DT