An amp for junior

[KT66]

I'd go for a 2 X 6L6 5E3. Remember Doveman's Supraluxe ? : http://ampgarage.com/forum/viewtopic.ph ... e&start=45 I thought that sounded pretty sweet, here's his Youtube clip of it : http://www.youtube.com/watch?v=V-2gNkXuTgk

[rdjones]

There are several options one could go with like the 5E3x2 (double Deluxe) like Weber has in their kit.

Or 6L6 as Bill stated such as the Ceriatone 5E3x2.

Mark

Another mistake in a Ceria layout ?
B+ from pin 8 on GZ34s, please.

rd

[wicker]

But won't 6L6 require higher p-p V to get overdriven ? (that's probably why most 6L6 amps use long tail PI) I would go for 4x6V6, with 400 or a bit more on anode, it would give probably ~40W. And heaving 4 octal sockets you could always try 2x6L6 (if cathode bias - got to change bias res.).

[azatplayer]

I did the double deluxe, used one of Mooses experimenters OT's and an express/pool PT. I ran it 4.3K OT with the 300V taps and used a GZ34.
Had around 370V on the 6V6's, at the upper limit, and it sounded fantastic.
Probably about as loud as my 5E7 build with 6L6's, maybe around 30 watts or so, pretty perfect really.
BUT what was fantastic, and i preferred, was pulling two tubes and dropping in a pair of KT66's. That was freakin fantastic.
I set one pair of tubes up with an adjustable cathode bias, so i could dial it in just right.
In hindsight, i would likely just build a super using either 6L6 or KT66. Great tones. AND in fact the 5E7 bandmaster i ended up building, i have setup with single 12, is in reality a 5E5 super.

[M Fowler]

Layouts should only be used as a guide not how to build an amp.

I see mistakes in a lot of layouts.

Mark

[skeezbo]

I think Azatplayer has it right: I built a kt66 5f4 tweed super with no feedback (like a deluxe) in a 1-12" combo. I did drift away from the deluxe with the use of the TMB tonestack from the bassman and a large grid stopper on the inverter to tame the overdrive. I set it up with fixed bias, but may change that. Great sounding amp!
Skeezbop

[rdjones]

Layouts should only be used as a guide not how to build an amp.

You are absolutely right, Mark.
I continue to encourage guys who are developing their skills to learn to read the schematic(s) and use them as the primary reference to a circuit.
The layout is just a byproduct of the schematic.

I see mistakes in a lot of layouts.

I see a lot of mistakes in Ceriatone layouts.

rd

[rdjones]

Much of the magic in a 5e3 circuit is the Cathodyne Phase inverter and the Cathode biased power tubes. I have heard a friends suped up deluxe with 6l6's , bigger PT and proper OT for the 6l6's . It is a monster. Twins , bassmans etc, do not sound like a deluxe, In my experience, they have Long tailed pair PI's and fixed bias.

After researching this subject a bit, I found only one single schematic from Fender that used 6L6s with both cathodyne PI and cathode biased outputs.
It's the 5E5 Pro Amp from 1955 and was quickly updated in 1956 to the 5E5-A with fixed bias, and more tone control.
The 5E5 looks nearly identical to the 5E3 Deluxe with the only treatment at the inputs and first stage being different, and a 5U4 in place of the 5Y3 rect.
2x6L6, 395 Volts B+, 2x12AY7, 12AX7 driver/inverter.

There's another issue with beefing the 5E3 circuit to 6L6 territory and that's sizing the output transformer.
It's well known that another part of the "magic" of the tweeds is the marginal capability of the OT.
When increasing the size of the OT I'd suggest not going above the size of a Blackface Pro or Bandmaster, and not going below 4.3k primary.
6.6k might be the ticket here for 6L6s.

I've never seen a 1955 Pro 5E5, and so have no reference to the size of it's output.

Anyone have a guideline for (minimum) output transformer weight to wattage ratio ?

rd

[rp]

There's another issue with beefing the 5E3 circuit to 6L6 territory and that's sizing the output transformer. It's well known that another part of the "magic" of the tweeds is the marginal capability of the OT. When increasing the size of the OT I'd suggest not going above the size of a Blackface Pro or Bandmaster, and not going below 4.3k primary. 6.6k might be the ticket here for 6L6s. I've never seen a 1955 Pro 5E5, and so have reference to the size of it's output.

Anyone have a guideline for (minimum) output transformer weight to wattage ratio ?

I've nothing technical to offer, but don't doesn't this look perfect:

http://www.mojotone.com/amp-parts/trans ... ri-Imp-4-8

[martin manning]

Anyone have a guideline for (minimum) output transformer weight to wattage ratio ?

About 15W/lb (BF Twin) to 17W/lb (Bandmaster).

[rdjones]

Anyone have a guideline for (minimum) output transformer weight to wattage ratio ?

About 15W/lb (BF Twin) to 17W/lb (Bandmaster).

Yep, that falls right in line with the Mojo output rp posted.

1.8# x 17 = ~30 watts.

rd

[rdjones]

Anyone have a guideline for (minimum) output transformer weight to wattage ratio ?

About 15W/lb (BF Twin) to 17W/lb (Bandmaster).

Yep, that falls right in line with the Mojo output rp posted.

1.8# x 17 = ~30 watts.

rd

I think I'm looking at this from the wrong perspective.
We should be taking the power to weight ratio of the original 5E3 output transformer and apply that to the expected power level of the circuit with 6L6's and the available transformer(s).

In other words, the BF Twin is known to have much better headroom than a Tweed so the 15W/# would be too conservative for the purpose of trying to recreate the core saturation of a Tweed.
What's the weight of an original 5E3 OT ?

Jim, get your calculator out and follow along here, pal.

rd

[martin manning]

If you slide on over to Antique Electronic's Fender replacement transformer page the listings include both wattage and weight. There's quite a bit of variation... from under 11W/lb to 18 for the ones I checked.

[Big Jim]

About 15W/lb (BF Twin) to 17W/lb (Bandmaster).

Yep, that falls right in line with the Mojo output rp posted.

1.8# x 17 = ~30 watts.

rd

I think I'm looking at this from the wrong perspective.
We should be taking the power to weight ratio of the original 5E3 output transformer and apply that to the expected power level of the circuit with 6L6's and the available transformer(s).

In other words, the BF Twin is known to have much better headroom than a Tweed so the 15W/# would be too conservative for the purpose of trying to recreate the core saturation of a Tweed.
What's the weight of an original 5E3 OT ?

Jim, get your calculator out and follow along here, pal.

rd

I am following along alright...What we are doing here is settling on a OT that is large enough to handle the 6L6's, yet doesn't make the amp clean up so much that it loses that aggressive gaininess of the original 5E3.....Right?

[Zippy]

Check in with Mission Amps website - that is one of Bruce's options for the 5E3 kit.