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basd45 11-12-2012 02:57 AM

Tube replacement advice
To anyone gracious with advice,
My amplifiers are about due for a tube replacement. They are both Laney TT100 combo amplifiers. Their output sections contain 4 EL34 power tubes and their preamps contain 6 12AX7 tubes. Here is a link to the owner's manual where a basic schematic is displayed:

Laney did not sell many of these amplifiers, so there is not much specific information for this amplifier, nor is there a large community of fellow owners to turn to for advice. The power tubes are not really too much of a concern for myself, but I would appreciate some advice on the selection of preamp tubes to accentuate the characteristics of these amps that I find desirable, and maybe tweak certain characteristics that I feel could be improved. As this is a three channel amplifier, I understand that the six preamp tubes affect different channels of the amplifiers, and I would like to ask for recommendations for the various individual preamp channels.

Channel 1:
Great sparkling Fender clean sound, amazing headroom, would like to keep these characteristics. I believe this channel is fed by the V1 preamp tube.

Channel 2:
Crunch channel that has a great semi-clean tone that will break up depending on your attack. This is accentuated by a drive control that when pushed approaches a moderate crunch akin to Keith Richards esque territory. I would like to keep the timbre of this channel similar to it's previous design. I believe this channel occupies the V2 & V3 preamp slots.

Channel 3:
"Lead" Channel is a relatively hi gain channel with a sound comparable to AC/DC. It has a relative high amount of noise, I consider the channel relatively unusable. I have a relatively elaborate fx board, and I rely on that currently for overdriven lead sound. This channel could be improved. New preamp tubes will make a difference hopefully. I would prefer a distortion comparable to Randy Rhoads as opposed to it's current Angus Young quality. This channel I believe is fed by the V4, V5, & V6 preamp tubes.

So any recommendations on particular tube selections for this amp design? If mixing and matching tubes for optimum sound is possible, any thoughts on tube selection to match my above-mentioned desired characteristics would be appreciated. It is my intention to replace the power tubes as well, but from my understanding as long as I steer clear of poorly crafted Chinese power tubes, there should not be a great affect on the timbre of the amplifier, if your opinion varies from this perspective, feel free to advise me on their selection as well. Thank you for your help.

KG6_Steven 11-12-2012 10:27 AM

I would recommend trying a 5751 in the V4 slot. The 5751 is a lower gain version of the 12AX7. It offers a gain factor of 70 versus 100.

As far as recommending specific manufacturers or tube types, I generally do not do that. The reason is, it's too difficult to say "try brand x and it will give you this tone/sound." Amps and ears are all different, so what works a certain way in one amp may work a little different in another. There may be some good Chinese tubes, but the general consensus is they're all bad. In regards to reliability, JJ, Groove Tubes, Mullard and Electro Harmonix all make good tubes. All of the NOS (New Old Stock) American made tubes are good, but the prices may scare you away. Just to clarify one thing I said a couple of sentences ago... I said that Groove Tubes makes decent tubes. Really, GT does not make tubes. They purchase tubes made by other manufacturers, then test and rebadge them with their logo. In essence, if you buy a GT 12AX7, you could be buying a JJ 12AX7. You pay a bit more, but hopefully there's a little less risk of buying a dud.

R45VT 11-12-2012 12:01 PM

KG6 posted some great information.

Every amp sounds different and you may want different sounds than others...

That being said JJ's are a great value. You may want to pick up another brand as well to play around with in the V1 spot as JJs tend to be a bit darker.

basd45 11-12-2012 08:29 PM

Thanks for the information, it is greatly appreciated.

Cathbard 11-12-2012 09:01 PM

Find me a schematic, not some dodgey block diagram that shows sfa.

For most of what you want I'd just use JJ ECC83S tubes but you may want something different in V1 if you want a clean channel more Fendery, perhaps an RCA 12AX7 or even a Phillips 5751. I need to see a schematic though or else I'm just pissing in the wind. "I believe" doesn't cut it. I have no time for beliefs, give me facts or gtfo. ;)

basd45 11-12-2012 10:27 PM

Does this help?

Btw this is the Internet, not the thunderdome, cool it Mel.

Cathbard 11-12-2012 10:41 PM

Yeah, that's much better.

V1 is actually common so anything you put in there will also affect the other channels as well.
With that in mind, hunt down a nice NOS 12AX7/ECC83 for that position and run JJ ECC83S tubes everywhere else.
You can often score RCA tubes cheap in the US and GE are even cheaper. The RCA's are marginally better. If you can find a Phillips 12AX7 that you can afford jump on it but they usually run to quite a bit of money.

If you can't find an American, British or Western European tube just stick JJ's in there. You may also want to consider a Gold Lion in V1 but they cost quite a bit too. If you are on a budget just throw JJ's at it.

basd45 11-12-2012 10:46 PM

Thanks for the advice,
From my own limited perspective, it appears that all three channels are fed thru V6. What would the function of this valve play upon shaping the timbre of the amplifier?

Cathbard 11-13-2012 12:35 AM

A little bit, it's the Phase Inverter. Some people like to run lower gain tubes in there, the JAN Phillips 5751 is pretty popular. It's actually part of the power amp. Just stick something decent in there and it will be fine. Unless I was hunting down NOS I'd just stick bog standard JJ ECC83S tubes everywhere. Ideally it should be a balanced tube in the PI but it doesn't really matter a lot.

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