| JTM pre-amp valves [message #27090] |
Tue, 05 July 2005 04:20  |
Matt5104
Messages: 1
Registered: May 2009
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Esquire |
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Hi, I have a JTM612 with 2 12AX7s, 1 12AX7EH and 1 marshall ECC83 in the pre-amp. I'm considering replacing them all with mullard ECC83s. Can I literally just replace them and power up the amp, or do I need to re-bias the amp? Also, does anyone know the best order in which to place the original valves in the pre-amp? I've heard that putting the 12AX7EH in V1 (first valve position from right to left) is best, but i'm not really sure! Thanks very much.
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| Re: JTM pre-amp valves [message #27098 is a reply to message #27097] |
Tue, 12 July 2005 13:50  |
Damir
Messages: 1005
Registered: May 2009
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Illuminati (2nd Degree) |
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I can say that even slightly microphonic tube have no place in my amps. And yes, we can say that first tube is the most important (noise and tone-wise), but their combination is what matters. It`s hardly subjective, for example - I found "Mullard" ECC83 good sounding, IMO - it doesn`t "break", but "softly and warm" compress - but too much for me. TFK ECC83 is arguably "best of the best", but in my amp (Fender "Deluxe Reverb") doesn`t work in the first position - overall sound was (too) clean and bright. But, in the 2nd position - that`s IT! And I (preffering "cleaner" sound) used 12AY7 or 5751 in the first position.
And yes, I changed reverb driver (12AT7) to 12AU7 and power amp driver (12AT7) to E180CC.
Once, my friend (owner of the profy studio) and I retubed some of his amps the whole day long - every combination (preamps tubes, output tubes, rectifier) we recorded (the same riff) on hard disc-recorder. Then we listened, and compared...huh. And yes - some of my favorite combinations/tubes didn`t work for him, but some other, pretty odd:-)
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