Preamp tube positions for Simul Satellite

[dmt]

I am wondering what is the function of the two preamp tubes in my Simul-Satellite amp? I beleive that one is the signal preamp and one is for the tone controls. If anyone knows I would appreciate it as I have been playing with some new preamp tubes I have received. It would be good to know what each coresponding slot does....

 

[Timbre Wolf]

Its a simple amp, but I sold mine at least ten years ago, so I'm not even going to attempt to go by memory. Mesa's basic amp structure is based on Fender designs, so I'd expect the tube closest to the input jack is the first input gain, and also the second gain stage (isn't there a pull pot on one of the volume knobs?). The second tube would be the tone circuit and driver tube. I'd expect a third 12AX7 for the phase-inverter, and this would be the small tube closest to the output valves.

What tubes do you have to try out?

- T

 

[dmt]

There are only two pre amp tubes.

My friend gave me several older tubes he recovered from various tube based equipment, 2x 12AX7A 2x 12AU7 and 2x 12AT7's. The 12AX7A's(labeled Lowery Organs) are made by GE or RCA back in the 60's and sound killer, the 12AU7's one is a British Dynascan (made in Japan) that was used in testing equipment, the other is a Sylvania MAde in USA and it is burnt as hell and breaks up very fast. The 12AT7's, one is marked CHY Hytron, and the other is another Dynascan. The tubes my tech placed in there are new Sovtek 12AX7WB tubes, which have a shorter plate and are larger diameter tubes, these sound very different as well.

I settled on a 12AX7A in the first position which I assume is the signal preamp, and the Hytron 12AT7 in other position (tone?) and it sounds killer.

 

[Timbre Wolf]

There are only two pre amp tubes.

My friend gave me several older tubes he recovered from various tube based equipment, 2x 12AX7A 2x 12AU7 and 2x 12AT7's. The 12AX7A's(labeled Lowery Organs) are made by GE or RCA back in the 60's and sound killer, the 12AU7's one is a British Dynascan (made in Japan) that was used in testing equipment, the other is a Sylvania MAde in USA and it is burnt as hell and breaks up very fast. The 12AT7's, one is marked CHY Hytron, and the other is another Dynascan. The tubes my tech placed in there are new Sovtek 12AX7WB tubes, which have a shorter plate and are larger diameter tubes, these sound very different as well.

I settled on a 12AX7A in the first position which I assume is the signal preamp, and the Hytron 12AT7 in other position (tone?) and it sounds killer.

If you're curious about the i.d. of all those tubes, post pictures and I'll do my best. The "Lowrey" may be GE or RCA, but is more likely Sylvania or Raytheon; does it have black plates? Short or long plates (14mm or 17mm)?

This may not matter, as you've done what you need to do with them - use your ears to get your favorite combo. But if you're wanting to get backups, its helps to know just what you're looking for.

If the Satellite only had two 12AX7, then the second one (closer to power tubes) is the phase-inverter. I typically prefer a 12AT7 for the phase inverter, too.

- T

 

[dmt]

Will post pics soon.

The Lowery Tubes have a Grey Plate, the plate is not as tall as the Sylvnia tube, not sure about 14 or 17 mm

 

[Timbre Wolf]

Will post pics soon.

The Lowery Tubes have a Grey Plate, the plate is not as tall as the Sylvnia tube, not sure about 14 or 17 mm

Sounds like "short" (14mm) plates, then, to me. If the mica disks are not entirely circular, but instead are trimmed parallel on either side, they are RCA.

Yeah, pix will help immensely.

- T

 

[dmt]

All Tubes:

Sylvania 12AU7:

Lowery Organs 12AX7A:

Lowery vs Sovtek 12AX7WB (new)

Dynascan:
12AU7:

12AT7:

HYTRON 12AT7:

Sovtek 12AX7WB (new):

Sovtek KT66:

Boogie: