Are 6sn7GT versus GTA/B safe in an MV60?

[rmac587]

Hi Folks,
I acquired an MV-60 (hyper-ventilating) and want to roll some stronger tubes into the 6sn7 position. I have some beautiful GT and GTA/B from a lot I recently bought. Here is the issue: the GT CANNOT be subbed in an amp designed only for GTA/B. It has max 300v plate dissipation, while the GTB were "enhanced" to 450v.

The upshot is that you have to make sure your amp can handle this. The manual doesn't seem to indicate either way. Any insights here? Does it even matter in this position in the MV60 which 6sn7 one uses?

Much Obliged Ya'll!

[roberto]

Hola Mac,

This is what your manual states regarding the tubes used in your MV-60: The MV60 uses eight vacuum tubes of three different types: two 12AX7A (V1 and V2), two 6SN7 (V3 and V4) and four EL34s (V5 through V8). The brands of tubes we supply have been chosen by first selecting those brands which are known to be most reliable, then by extensive auditioning of these acceptable brands with the final choices being made solely on the basis of sonic performance. We know of no vacuum tubes available which will improve the sonic performance of your MV60. We highly recommend that you purchase replacement tube sets from conrad-johnson design.

Tube rolling sometimes is not a good thing. Conrad Johnson is very picky with the tubes used in its design. At thetubestore.com you can find different brands that make this tube. Changing it might cause an improper function of the power supply of the unit.

Happy listening.

[rmac587]

Thanks Roberto,
Totally understand. I have new production tubes from you guys in my preamp. That said, I do like to try different tubes, and it is convenient to have spares on hand if I need them immediately. So it is safe to use GT? Can you let me know what new production you would recommend?
Thanks, Rob

[roberto]

Rob,

Groove Tubes are made basically for guitar amplifiers. You could try use them, but use only the same number as the original tube. Just try and have a listen. Remember that our immediate memory is worthless for comparison. Write down your findings of music that you are very familiar with it, and play the same music. Don't hurry. Take your time for the comparison. Choose the ones that you liked most. If there is no evident benefit, keep the original.

Happy listening!

[AnotherJohnson]

Thanks Roberto,
Totally understand. I have new production tubes from you guys in my preamp. That said, I do like to try different tubes, and it is convenient to have spares on hand if I need them immediately. So it is safe to use GT? Can you let me know what new production you would recommend?
Thanks, Rob

Please keep in mind that this forum is not an official conradjohnson design sponsored site. Many here, including me, are just enthusiastic users, and no one has a role as CJ representative, although a couple do work for or as dealers.

Regarding guitar amp tubes vs audiophile amp tubes, the goals of the amps are different.

With an electric guitar, the amp becomes a major contributor to the sound. The amp is literally part of the instrument. Amps intentionally shape the sound, add reverb, and even overload tubes to intentionally add distortion. The guitar player controls all these things with dials and switches on the amp and on the guitar.

With an audiophile amp, the goal is to faithfully reproduce what was on the original recording without adding any colorations (tone shaping) or distortions.

Tubes that would be perfectly good for use in a guitar amp may be unable to perform the task necessary in an audiophile amp.

It is fine to use audiophile grade tubes in guitar amps. It is not a sound idea to use guitar amp grade tubes in audiophile amps.

[rmac587]

Thanks Roberto and Another Johnson-I'm new to CJ and the forum, relatively speaking. I have a lot of various 6sn7 and 12ax7. My main power tubes were fortunately replaced with EL34 from CJ not long before I bought the amp. I'll let my ears be the judge.
Peace, Rob

[rmac587]

Hi AnotherJohnson,
Sorry to be unclear, by "GT" I mean the actual tube designation of the original production 6sn& rather than the Groove Tube brand. BUT, I'm glad you mentioned it as one of my spare EL34 is a random Groove Tube!
Thanks, Rob