Tweed Deluxe Pre-amp voltages

[Doc Simons]

I have a Tweed Deluxe 5e3 clone with a Kendrick PT which puts out about 330V from the secondary. My preamp tubes are running at about 140v. Is that where they should be? Seems awfully low compared to the 170v-180v in my '66 Deluxe Reverb or 270-280v in my '68 Super. None of the schematics I have found give voltages for the tweed.

[wyatt]

Well, plate voltages will be lower in Tweeds, that's one of the reasons for their lower headroom and a looser, more responsive behavior. As plate voltages go up, so does preamp headroom and stiffness.

But, on average, assuming a B+ of ~375VDC (that varies a lot depending on PT used)...

V1 (12AY7) ~120VDC on both plates (1st gain stage)
V2 (12AX7) ~140VDC on pin 1 (2nd gain stage) and ~190VDC on Pin 6 (PI)

[ToneMerc]

That's one of the charms of the Tweeds, the lower voltages and it seems about right dependijng upon your AC mains. I've always assumed that Kendrick and Mission used modern transformers with vintage voltages.

TM

[rp]

i checked my clone notes, I also have a 330-0-330V loaded @ 120mA with NOS 5Y3 and NOS V1 12AY7 & V2 and pre plates are 180-200V, 6V6 plates ~340V. Different tubes will draw different currents and will have different Vps all else being equal, but yours do seem a little low (or mine might be high?) there is no Fender values for the 5E3 so who knows. I also have ccs, they could be off a bit, had it a long time. You might want to poke around a bit, however. And BFs ran higher voltages in the preamps so you can't compare there. Check the other 6V6 tweeds. If all is fine, try a 5V4 for a little boost.

[wyatt]

i checked my clone notes, I also have a 330-0-330V loaded @ 120mA with NOS 5Y3 and NOS V1 12AY7 & V2 and pre plates are 180-200V, 6V6 plates ~340V. Different tubes will draw different currents and will have different Vps all else being equal, but yours do seem a little low (or mine might be high?) there is no Fender values for the 5E3 so who knows. I also have ccs, they could be off a bit, had it a long time. You might want to poke around a bit, however. And BFs ran higher voltages in the preamps so you can't compare there. Check the other 6V6 tweeds. If all is fine, try a 5V4 for a little boost.

Your numbers seem higher than average, especially for V1.

[Doc Simons]

Thanks. I actually am using a 5v4. I also replaced the 22k resister in the power train to 10k, which got the preamp voltages up a little and improved sound, but not a lot. 5K is too low and I get bad distortion/inadequate filtering. Any other suggestions?

[pops]

I like to see 300v on the plates of the power tubes and whatever the preamp tubes end up is fine with me. I have had as low as 105, it should be above 100v, i wouldn't worry about lower preamp volts as much as to high a power tube voltage.

[Guus]

Hi Doc Simons,

I think the preamp voltage is fine.
The tweed amps (and a lot of older tube amps) mostly have around (10%)150 Volts on the preamp plates.
A tubeamp specially made for harmonica has even a lower plate voltage (~100V)
A low plate voltage, and small electrolytic caps, gives a little headroom and the often wanted brown sound.

The newer Fender amps like Blackface de luxe reverb, have a higher plate voltage (around 200V) and so have a lot more headroom.

If you want a different sound, experiment by changing the powerstring. Upping the platevoltage preamp will give you a cleaner sound, if thats what you want.
Tip: If you want to stiffen the lows , experiment with upping the first electrolytic cap.

grtz
Guss

[rp]

You bums made me go open my 53E and recheck. My notes were from years ago and US. Here in EU I now have 345Vac on the rectifier loaded instead of 330V@120V I had. I had this custom wound and I may have spec'd 220V or 230V instead of 240V, I have 6.8 on the heaters too so that may be it.

So if anyone cares with 237V/wall, 345Vac sec, NOS 5Y3 371V pin 8, 4.7K & 22K string, 360 Vp, 12AY7 V1 1&6 ~120V, V2 1&6 ~163/200V. So my V2 is a little hot by typical 5E3s?

I replaced the 5V4 with a 5Y3 as it was giving me 395 Vp. Was sounding killer even though I was convinced I preferred lower voltages in these. Either way, as long as it doesn't smoke I'll call it a success.

[wyatt]

So if anyone cares with 237V/wall, 345Vac sec, NOS 5Y3 371V pin 8, 4.7K & 22K string, 360 Vp, 12AY7 V1 1&6 ~120V, V2 1&6 ~163/200V. So my V2 is a little hot by typical 5E3s?

No, that seems about right.