Need Low gain and Bright 6L6's, and Preamp 12A?? tubes

[giogolf]

Hey all,

I am getting along a lot better with my high powered 5e3 lil'dawg D'Lux 35 watter. I now want to experiment with some tubes. Right now with NOS GE 6L6's, 12AX7, and 12AY7 my amp overdrives with the volume at 3 on the bright channel.
I want to experiment with some tubes that will clean it up just a touch and add some brightness. Where is a good place to start with 6L6's and 12A?? When I bought this amp I had a choice between NOS and JJ's, Jim told me the JJ's would be more aggressive than the NOS, so is there anything less aggressive than NOS? Also can I put 2 12AY7 in the preamp to minimize the gain? Thanks

[Billm]

Definitely try a 12AY7 in the preamp. Why not use input 2 if you want clean headroom? That's what the jazz players do.

[giogolf]

From more to less gain is this correct:
12AX7 More Gain...
12AT7
12AY7
12AV7
12AU7 Less Gain... Would it be crazy to use 2 of these?

[Billm]

Yes, but the 5751 goes between the 12AX7 and the 12AT7. It's about 80 percent of the 12AX7 and it has the same high plate impedance as the 12AX7, so it won't alter your tone (other than the normal difference among tube manufacturers).

The 12AT7 and 12AU7 are driver tubes. They have lower impedance and high current capabilities. The lower impedance generally causes some loss of highs. Some people like them in a preamp because they're mellow; others don't because they kill high end.

The 12AY7 has the third-highest impedance after the 12AX7 and 5751. It's a proper preamp tube. It's what the 5E3 was originally designed around.

The 12AV7 is really a switching tube. It's designed to drive relays and such at high currents and is optimized for being fully on or fully off.

Two 12AU7s would give you a practice amp--pretty darn quiet. No breakup.

[giogolf]

Well I definitely do not want to warm the amp up any so adding brightness or staying where it is now would be great. Do you think trying 2 12Ay7's is a good starting point?

[schmerf]

I've got a 25 Watt D-Lux. It is not a headroom machine by any stretch. I found I got the most headroom with SED 6L6GC winged "c" power tubes and a 12ay7 in v1 and a 12ax7 in v2. I've found for preamp tubes a lot of my old 70's Fender stock preamp tubes are bright in a very pleasant way and for new production I've found EI preamp tubes to be bright and musical.

[Billm]

The original 5E3 used a 12AY7 for the preamp and a 12AX7 as a driver and a phase inverter. You should try it that way to see what you get, especially using input 2 for cleans. Or is that too clean for you? I have experience with the Weber 5E3 Proluxe, which is the same idea as your amp. Using 5881s, input 2 was just plain beautiful.

You're using a 12AT7 in V2 now, so a 12AY7 might sound a little brighter and a little quieter than the 12AT7--hard to say. You might also want to try a 12DW7 in V2. It's half 12AX7 and half 12AU7.

[giogolf]

I will give it a shot

[marshman]

Bill-is V2 the PI? Would you want a tube in there with different values like that in that position? Isn't that where you'd want one of the 'drivers', like the T or U? I've never tried one (a 5E3) but I'd think if max headroom was the goal, a 12AY7 in V1, a 12AU7 in V2, and maybe then adjust power tubes to taste.

[Wally]

I think that I would start with the 12AY7 in V1 and 12AX7 in V2 as FEnder originally used in the circuit. AFter that, try a 12AT7 or a 5751 in the PI.
AS Marshman says, don't be afraid of taking a look at increasing the resistance in the bias circuit. This will clean and brighten things..increased headroom and all. Lower current draw increases the plate voltage. That would be a consideration when approaching things in this area.

[ASATmarty]

The brightest ax7 I've ever tried is Sylvania.

[woodman]

just swapping the AX for an AY in v1 will make a big difference. i'd try that first, then go from there. no worries in using different value tubes for v1 and v2.

[Billm]

And because the 5E3 uses a concertina phase inverter, you can use an unequal tube like the 12DW7 in there. Only one triode does the phase inversion, and in concertina form, it's a non-gain stage. So it shouldn't affect the output level.

Conversely, you could use a 12DW7 in V1 and have a high-gain and low-gain channel.

[Dacious]

Giogolf, it sounds to me like you may have the wrong amp: sorta like you want a Blackface/Silverface scooped tone with a sparkly top end What you have is Tweed tone, which is rawer, not as nice, doesn't have the same highs, and a lot more midrange.

If you have a cathode bias amp it is never going to sound exactly like a grid bias unit. Some of it is design, and some of it is component values in the preamp. I don't know if you can go back to 6V6s, but if so they will net you better treble response (brighter) IMO than 6L6s ever will.

Have you spoken to the amp maker for their recommendations?

[emu!]

Originally Posted by Billm

Conversely, you could use a 12DW7 in V1 and have a high-gain and low-gain channel.

Billm:

This is great info. I didn't know that there was such an animal. I googled 12dw7 and found the tube data. Looks like triode 1 has an amplication factor of 100 and triode 2 has an amplication factor of 17.

Do you know of any other preamp tubes that have different triodes in the same bottle...that can fit in a 12ax7 socket?

[4 Strings]

Originally Posted by emu!

Billm:

This is great info. I didn't know that there was such an animal. I googled 12dw7 and found the tube data. Looks like triode 1 has an amplication factor of 100 and triode 2 has an amplication factor of 17.

Do you know of any other preamp tubes that have different triodes in the same bottle...that can fit in a 12ax7 socket?

There is a "mirrored" 12DW7 too, where triode 1 has an amp. factor of 17 and triode 2 has 100. I just can't remember what it is called, perhaps Billm does?

In a circuit such as the 5E3 with a concertina PI this could make a difference if you either want to push the PI triode of v2 with 17 % and the other with 100 % or vice versa. Never tried it myself though.

[giogolf]

Originally Posted by Dacious

Giogolf, it sounds to me like you may have the wrong amp: sorta like you want a Blackface/Silverface scooped tone with a sparkly top end What you have is Tweed tone, which is rawer, not as nice, doesn't have the same highs, and a lot more midrange.

If you have a cathode bias amp it is never going to sound exactly like a grid bias unit. Some of it is design, and some of it is component values in the preamp. I don't know if you can go back to 6V6s, but if so they will net you better treble response (brighter) IMO than 6L6s ever will.

Have you spoken to the amp maker for their recommendations?

I am really digging this amp now after understanding more on how the dynamic controls work. I do like the SF/Black Face amps, but for tubey blues overdrive this amp is amazing. I am just trying to get a decent bright/clean sound out of this amp so I don't have to use 2 amps when I gig.

[eugenedunn]

I've heard about that 12DW7 tube and it's uses in the Phase Inverter position.

I've heard that it can be used in the Princeton Reverb also. One half of the tube (the 12AU7) drives the Phase Inverter circuit. The other half functions as what? Is it a driver for the power amp section or the other half of the tremelo oscillator circuit? Does anyone have insights or experiences with this substitution?

[Scott S]

Originally Posted by 4 Strings

There is a "mirrored" 12DW7 too, where triode 1 has an amp. factor of 17 and triode 2 has 100. I just can't remember what it is called, perhaps Billm does?

In a circuit such as the 5E3 with a concertina PI this could make a difference if you either want to push the PI triode of v2 with 17 % and the other with 100 % or vice versa. Never tried it myself though.

JJ Electronics makes an "ECC823", which is the mirror version of the 12DW7/7247/ECC832. While not unafraid to rewire my amps, I'd pick whichever tube put the 12AU7 triode as the PI with the stock wiring.

- Scott