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I was hoping you guys could shed some light on which preamp tube positions affect each channel the most. I have a couple of Nos Mullard and Siemens ecc83's that im using in the amp now and want to experiment with some different placements. One of the tubes test as high gain and i wanted to see if it would make a noticeable difference in the TMB channel. Which position (v1 or v2) has the most effect on the TMB channel? I'd really appreciate any knowledge you guys could share with me, thanks!

TMB Channel = V2
Normal Channel = V1
PI (affects both channels) = V1 and V2

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http://pdfelectronics.com

Excellent, thanks!

Also bear in mind that the two sides of V1 are the first preamp triodes for both the Normal and TMB channels. Also, the second half of V2 is just a cathode follower, with no voltage gain benefits. So I might be inclined to put the high-gain NOS tube in the V1 position.

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Great tones come in small glass jars!

Thanks Zaphod! I thought v1 was common to both channels but i wasn't positive. If the second triode in v2 is the cathode follower, is the first half of v2 being used by the TMB channel or the normal. I want to make sure i'm reading the schematics correctly before attempting my first kit build. The amp i have now i bought used, and wanted to get my feet wet with some of the suggested gain mods here on the forum and work my way up to building my own 18 watter.

Going from memory, the first half of V2 is being used in the TMB channel.

Just be careful with high gain 12AX7s. Sometimes they're also more noisy than the regular kind.

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Great tones come in small glass jars!

Gotcha, i''ll keep that in mind. In principle, would using a higher gain preamp tube in the PI slot drive the output stage any harder or am i setting myself up for more noise there also? Im about to purchase a few more NOS ECC83s and i want to make an informed buying choice before spending so much. As always, your opinion's are greatly appreciated!

A strong V1 will drive the preceding stages harder (including PI and output tubes) so I'd say use that high gain strong tube in V1 not the PI.

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http://pdfelectronics.com

Thanks for the help guys! I'm off to do some tube tasting now...I'll let you know what work out the best.

Well I was finally able to do some testing tonight at band practice and i have to say that I didn't like the hi gain tube in the V1 spot. The tube was an NOS prewar EI ecc83 that was tested as "hi gain" from a dealer I have been using. In V2 I had another EI,and for the phase inverter I was using a Siemens ecc83. The sound I was getting was a little raspy and thin I thought. Next I decided to try an NOS Mullard ecc83(late 60's) in the V1 spot. I wasn't expecting anything drastic but i must say that it really did thicken up the sound quite a bit and definitely highlighted the mids while eliminating that raspy high end I was getting. A much more pleasant overdrive with the Mullard than the EI in the first position. It definitely made me a believer that a Marshall circuit sounds great with the older Mullards! Next time I will experiment with a higher gain ecc83 vs a lower gain 5751 in the PI spot and see what the differences are there.

I've been having really good success with NOS Sylvania's in all of my amps. Specifically those branded for Baldwin organs. They seem to provide full tones with a nice level of distorion while not sounding harsh. Of course NOS, like all tubes, can be a bit of a crapshoot. Good luck.

(Metroamp 50 watt plexi, Trinity Tramp, Trinity Triwatt)

I have heard good things about them also and you can still find them alot cheaper than the european brands. I might pick up a couple soon and try them out...thanks!