Audio Research SP11: tubes & dampeners

david winter

Classical music lover.
Hi,

I got my SP11 back from a long time loan.
It currently has three Sovtek 6922 with cracked dampers and three ECC88 gold pin by Cool Valve.
I haven't tested the tubes yet but my questions are rather simple:
- What was originally installed in the SP11 and are the above tubes good enough (especially the Sovtek) ?
- Would any actual model of damper replace the old cracked ones ? Supposing they can reduce microphony, should they be placed around the plates or is this not critical ?

Thanks !
 
Place the dampers around the micas.

Don't know if you have one or two dampers per tube, but you can put one around the lower mica and another around the upper mica.

Find silicon dampers for 9pin small signal tubes, ex:12AX7 , 12AU7 , 12AT7 , the all are of the same size.

Sovtek is not bad, don't know the other brand.

6DJ8 tubes make substancial difference in sound from one brand/model to another, have fun tube rolling.

6922 are like E88CC , like mil a spec 6DJ8 / ECC88 , have different charectiristics but are interchangeables.
 
Hi,

I got my SP11 back from a long time loan.
It currently has three Sovtek 6922 with cracked dampers and three ECC88 gold pin by Cool Valve.
I haven't tested the tubes yet but my questions are rather simple:
- What was originally installed in the SP11 and are the above tubes good enough (especially the Sovtek) ?
- Would any actual model of damper replace the old cracked ones ? Supposing they can reduce microphony, should they be placed around the plates or is this not critical ?

Thanks !

It seems Sovtec tubes were the tube of choice for ARC. My SP-15 preamp came stock with 3 Sovtek 6922 tubes in the phono pre that were getting weak so I replaced them with some 1966 bugle boys and they work very nice. But the stock black damper rings were rock hard and had to be chiseled off the tube so circular filed the whole batch and bought new clear silicon rings off the bay and also replaced the 8 black ones on my ARC vm220 tube amps as they too were begining to hardened. I've seen nudie picks of the new ARC stuff showing double black rings next to each other around the upper micas, like recommended by mroboto. I used a single ring on each tube but never experienced microphonics with my set up so for me it was just a preventative measure.

Besides, I like the clear silicon rings cuz it don't block the glow of the tubez...:biggrin:
 
Thanks for your answers.
Any preferred model on the bay or just the cheapest one ?
As the preamp is a (almost) closed box there's no need of any special model for its visual purpose.
The original dampers have a square section. I don't mind putting O rings instead but I don't want to buy rings purchased for almost nothing and sold at audiofool prices... :)
 
ARC gear is know for running tubes hard. Sovtek makes rugged tubes that hold up well. Audio Reasearch use Sovtek tubes often and that's what I always went for when I owned ARC.
 
McMaster-Carr has many high temp silicone o-rings to choose from, cheap too.
 
I know McMaster, I used to buy round belts 10+ years ago but then they started cancelling my orders for being "too small" considering my location (France).
Any recommended type on the bay or just any high temp silicone ? I' prefer rings with swquare section instead of round, to get a better contact surface. But that's just a thought. Could be wrong....
 
Thanks. Didn't find him (didn't search for long) but bought 20 for under $3 from China.
Will see how these look like once received. If not satisfactory I'll check again.
In any case, I guess almost any silicon ring will do ?
 
Yes, any, you may have little to no energy to absorb from vibrations, unless you crank music volume very high and speakers are close enough for the vibrations to reach the tubes.
 
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