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Audio Research SP6b

javajam12

javajam12

Active Member
Hello - I just purchased a cherry Audio Research SP6b and am trying to find out what brand ARC used for tubes. They are all 12ax7's and look like my old
Dynaco branded tubes that came with my PAS3. These are not Telefunkens as
they don't have the engraved logo on the bottom. I believe they are Mullard
tubes. Now, I don't know if the tubes that ARC used are reissues of the design
of the Mullard or what? Anyone know? They don't have any markings on them
whatsoever. Ideas? Thanks!
 
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I've heard the SP-3 used the Amperex, but I'm not sure what came in the SP-6. ARC is not supplying that tube today, but you can call them and ask what they use today to retube the SP-6.

Are you looking for the original sound or just knowledge of how it was?
 
Depends on when it was made. I've seen Audio Research branded Sovtek tubes... can't remember from what model, of what age, but I think I still got a few of those leftover tubes from one of those, in a box here...

BTW: Mullards and other Philips-family tubes will usually have two rows of VERY TINY characters stamped onto the tube, just above the base. Usually two rows of 3-4 characters each. If they're there, then it's definitely Mullard, Amperex, Philips, Valvo or something like that.

Can't remember where it is- but I once found a resource that had a reference chart, which decoded those Philips-type codes... where the tube was made, when it was made, etc. It's out there somewhere, I think, still...

BTW^2: SP6B = GREAT PREAMP. One of the very best ARC built, IMHO. Don't let ANYONE talk you into "upgrading" it to an SP6C. The B version is FAR SUPERIOR, IMHO and IME...

Regards,
Gordon.
 
My SP6 c1 came with EI 6922 in the last position when the pre came to me. There was one RFT 12ax7 that was ARC branded but I'm not sure what position it in was originally. Both RFT and Ei were main producers at the time these were built as both American and European manufacturers were getting out of tubes.
On a good note they were fairly well regarded. RFT purportedly being based on Telefunken design.
I recently retubed mine with Sovtek 12ax7LPS in the first position (low noise tube recommended) and Mullard 12ax7 (longplate) reissue in the second with pleasing result.
 
GordonW said:
Depends on when it was made. I've seen Audio Research branded Sovtek tubes... can't remember from what model, of what age, but I think I still got a few of those leftover tubes from one of those, in a box here...

BTW: Mullards and other Philips-family tubes will usually have two rows of VERY TINY characters stamped onto the tube, just above the base. Usually two rows of 3-4 characters each. If they're there, then it's definitely Mullard, Amperex, Philips, Valvo or something like that.

Can't remember where it is- but I once found a resource that had a reference chart, which decoded those Philips-type codes... where the tube was made, when it was made, etc. It's out there somewhere, I think, still...

BTW^2: SP6B = GREAT PREAMP. One of the very best ARC built, IMHO. Don't let ANYONE talk you into "upgrading" it to an SP6C. The B version is FAR SUPERIOR, IMHO and IME...

Regards,
Gordon.
Click to expand...

Thanks Gordon - I think they may be Sovteks. They have a tiny number
etched into the base of each tube. The SP6b sounds very magical and I don't
have any plans to upgrade it in any way. I'm very happy with it.
 
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