[Njychen]

Sounds good,

If you can conveniently try another 6SN7, then that would be a good experiment. Otherwise, it's most likely that your unit needs factory diagnosis and repair.

Please, do not hesitate to contact ALO directly once you are ready to arrange shipment for repairs. I contacted Ken Ball about your problem, and he's ready to work with you.

Very sincerely,

--Thomas

Will give the 2 new tubes a try. Will contact ALO directly if no go. Thanks for your help Tom.

 

[TomSix]

Update:

Just tried swapping the 6SN7 on the phono with the one on Studio 6. The imbalance is still there albeit seemingly less severe (channel balance knob at 2’o clock instead of 3’o clock)

Studio 6 sounds fine with either tube and a different source and only sounds off when using phono as source.

I have 2 more 6SN7 coming this week. Will try those and report back.

Yes, very good sir.

There should be very little gain variation between the triode halves in a quality 6SN7, but this is worth trying all the same.

Do keep us posted.

--Thomas

 

[TomSix]

Most likely, your phono will indeed need factory attention based on the unit's behavior.

ALO will certainly work with you to make things100% right

--Thomas

 

[Njychen]

Yes, very good sir.

There should be very little gain variation between the triode halves in a quality 6SN7, but this is worth trying all the same.

Do keep us posted.

--Thomas

Just tried 2 new tubes, imbalance is still there. Most likely the phono itself.

Only thing I’m not able to try is swap out both 12AX7 since I don’t have other ones. But I did swap left and right and it didn’t change anything so I’m doubtful.

Seller told me that he is waiting to hear back from ALO so I guess I’ll wait and see.

Thanks Tom and everyone else who responded.

 

[TomSix]

Sir, I initially misunderstood, and had the erroneous impression you *had* already tried different, new 12AX7 tubes.

I understand now you *only* switched the location of the two original 12AX7's in the unit.

The way it is constructed, the Studio-Six phono preamp has a gain stage of *BOTH* L&R channels in *each* individual 12AX7 tube. So, in fact there are *not* a single dedicated individual L or R channel stages in each tube, rather each individual tube has an L half and an R half inside of it.

Therefore.... if one channel is weak within *either* of the 12AX7 tubes, then swapping the 12AX7 tubes between socket positions would *not* change the channel in which the imbalance occurs.

The next thing to be done, would be to obtain a known good 12AX7 tube and alternately try this new tube in each of the existing 12AX7' sockets --in this way we can know for sure if one of the 12AX7 tubes is bad.

Please contact your dealer with this information, and he/she should be able to supply you with a new 12AX7 for this test.

Most likely, this will reveal one of the two 12AX7's is indeed at fault and causing your level mismatch problem. If this is found no to be the case, however, ALO is ready to assist further to get your unit repaired.

I apologize again for my misunderstanding, and thank you again for your patience and assistance in diagnosing your unit.

As soon as you are able, let us know what you discover by trying a new 12AX7 tube.

--Thomas

 

[Njychen]

Just tried 2 new tubes, imbalance is still there. Most likely the phono itself.

Only thing I’m not able to try is swap out both 12AX7 since I don’t have other ones. But I did swap left and right and it didn’t change anything so I’m doubtful.

Seller told me that he is waiting to hear back from ALO so I guess I’ll wait and see.

Thanks Tom and everyone else who responded.

Can I test with 12AU7s? I don’t have other 12AX7s at the moment.

 

[bcschmerker4]

Can I test with 12AU7s? I don’t have other 12AX7s at the moment.

I've experience with tube type substitutions on 1960's-vintage Fender Electric Instrument Company amplifiers. The 12AU7 is a medium-µ twin triode with 2200µS transconductance @ Vᴄ = -8.5 VDC @ Vᴀ = +250VDC; the 12AX7A, a high-µ twin triode with 1600µS transconductance @ Vᴄ = -2.0 VDC @ Vₐ = +250VDC: Both in a Class A₁ amplifier application. The 12AU7A will lose you substantial gain. I don't know the LCR context in the Studio Six; but in the 1964-65 Bassman head (AA165), the 12AU7A lost 9 dB on the 7025A, a now-discontinued high-µ twin triode that split the 12AT7A and 12AX7A for gain.

 

[Njychen]

I've experience with tube type substitutions on 1960's-vintage Fender Electric Instrument Company amplifiers. The 12AU7 is a medium-µ twin triode with 2200µS transconductance @ Vᴄ = -8.5 VDC @ Vᴀ = +250VDC; the 12AX7A, a high-µ twin triode with 1600µS transconductance @ Vᴄ = -2.0 VDC @ Vₐ = +250VDC: Both in a Class A₁ amplifier application. The 12AU7A will lose you substantial gain. I don't know the LCR context in the Studio Six; but in the 1964-65 Bassman head (AA165), the 12AU7A lost 9 dB on the 7025A, a now-discontinued high-µ twin triode that split the 12AT7A and 12AX7A for gain.

Thanks for explaining. I understand it’s not a direct replacement. Merely seeing if it’s safe to use them to find out what is causing the channel imbalance: the tubes or the phono.

 

[TomSix]

Can I test with 12AU7s? I don’t have other 12AX7s at the moment.

Unfortunately this would not be advised. The 12AU7 is a much different tube than the 12AX7. Damage to your unit could potentially occur if a 12AU7 is inserted into a 12AX7 position.

Fortunately, any quality known-good 12AX7 type would allow you to diagnose your existing 12AX7 tubes, and so that's really the only advisable route.

Do let me know what you find out.

 

[Njychen]

Unfortunately this would not be advised. The 12AU7 is a much different tube than the 12AX7. Damage to your unit could potentially occur if a 12AU7 is inserted into a 12AX7 position.

Fortunately, any quality known-good 12AX7 type would allow you to diagnose your existing 12AX7 tubes, and so that's really the only advisable route.

Do let me know what you find out.

Thanks. I will hold off till I have other 12AX7 tubes to try and report back.

 

[fixated]

Anyone know of any good reviews/impressions for the Phono Stage compared to the schiit mani ? I've been eyeing the Phono Stage for quiet a while now and its gotten even more tempting given that it's on sale. I don't have the option of demoing it unfortunately.

 

[longbowbbs]

Considering the power source for it is the S6 I doubt there has been any direct comparison. Quite a price difference there.

 

[fixated]

Just received the Phono Stage and liking what I'm hearing. I apologise if this question has been asked but where can I get a custom length power cord for connecting the Studio Six to the phono stage, I'm finding the current length to be too short. TYIA

 

[longbowbbs]

Call ALO. They should be able to make a custom length for you.

 

[fixated]

Call ALO. They should be able to make a custom length for you.

Thanks ! Will give it a try.