40 Watt Deluxe Reverb?

[72Blazer]

I've got a Deluxe Reverb Chassis (tube rectifier) and all the trannies for a Super Reverb   I would be putting this in a head cab (which I have) and use an extension speaker cab.  Obviously the Deluxe Reverb uses 2 6V6s and a Super Reverb uses 2 6L6s.
This chassis does not have cutouts for the bright switches and I can live without them. I would need to figure out how delete/rewire that part of the circuit.  OR, would this be as simple as following the Deluxe Reverb wiring and using the iron from a Super Reverb and 6L6s vs 6V6s

What reverb tank would I need and am I missing any “gotchas”? 

Vr
J.

[jordan86]

Removing the bright switch is very simple. Doesn’t change layout of volume pot or standard scheme. Best thing to do is download a super reverb schematic in addition to the DR. Both AB763 circuits. As you’ll see, besides iron and power tubes, things will be nearly identical. Print both schematics and highlight component differences. Good exercise.

Biggest headaches may be your transformer cut outs. The stock sized ones for DR may be too small for SR iron

[sluckey]

Main thing... Will the PT fit?

You can use a 1M-A Volume pot with pull switch for bright switch. Hoffman sells them. You'll lose a MID pot.  Differences in the power supply droppers. Same reverb.

Just put the two schematics side by side. You can figure this out.

[72Blazer]

OK.  Thanks!

This will be a learning experience.  I'll check out the PT chassis cutout-it probably is going to be an issue.

[72Blazer]

Dang it I just made an order with Doug about an hour or so ago.  Is it too late to modify my order?  Hell I can't even find my order I just made on the site....

[72Blazer]

Never mind-I just read that I cannot add to an order/change it and that I must make a new order.

[dude]

Pretty simple to run 6V6's in a Super Reverb, just takes a few values changes, look at Hoffman's 6V6 Plexi or the Deluxe Reverb and the Super Reverb here. Look at the components for the 6V6's and 6L6's, do these changes and you're done, might have to change a resistor or two in the bias supply. But you won't have 40 watts, more like 22. 

[72Blazer]

Hey Dude thanks for the info/recs-much appreciated and I'm comparing.  I'm actually going to try dougs AB763 circuit in a deluxe reverb chassis and going to use Super Reverb Iron and 6L6s.  Sluckey turned me on to 1M push pull pots for volume/to use as the bright switches-which my chassis does not have those particular cut outs obviously.  I ordered them (pots) from this site.

I would like any recommendations you have for speaker "Single 12" or maybe 2 x 10".  This is going in a FDR head cab I scored years ago.  Extension speaker cab is TBD @tt.

[72Blazer]

I've also got these on-hand.  Mojo761 PT and a Tone Clone FBFVO-40 OPT

Could they be used together on this build the AB763 circuit and if so, would the output power be more than a stock deluxe reverb?

This PT fits my chassis

[jordan86]

Eminence GA-SC64 for single 12”

Or Celestion Alnico Gold

[sluckey]

The Mercury OT is for a Vibroverb, 2x6L6 and 40 watts. It's fine.

But the MOJO PT is for a Deluxe Reverb, 2x6V6 and 22 watts. The 150mA is too lite for a 40 watt amp.

[72Blazer]

Thanks,

That's something I obviously do not understand yet.  I did notice the difference in the FDR (150 mA) and FVR (300mA) PTs.  Has this to do with the difference between what 6V6s and 6L6s need or what the pre-amp tubes need/initial signal to amplify?  Tying to learn some theory here.

Vr
J.

[sluckey]

The preamps are the same for a 22 watt AB763 and a 40 watt AB763. It's all about the power amps. It takes approximately twice as much current to make 40 watts as it takes to make 22 watts. (P = EI)

Stated another way... Little tubes plus little iron equals little power. Big tubes plus big iron equals big power.

[72Blazer]

And the math/test data does not lie.  Thanks Sluckey.

[pdf64]

It’s a weird legacy thing how Marshall 50W type PT HT windings are rated at 150mA, even though total current via the CT can approach twice that when cranked.
It seems to hark back to 350-0-350 @ 150mA being the spec of the ‘off the shelf’ Radiospares PT used in the first few batches.

[sluckey]

I suspect Fender's power ratings were based on considerably lower distortion percentages than Marshall's power ratings.

[SILVERGUN]

I like the Hammond 290CX for this application. It's pretty compact but I've had to trim out the hole on a Princeton chassis to make it fit. It might go straight into a DR hole.  It's now listed as a "DR Reissue" application, but I've seen it listed as a 40W.

The Reissue DR spec says 180mA, but this xfmr is clearly capable of more. The label lists it at 325-0-325 @ 207mA.

290CX (hammfg.com)


EDIT - I just noticed where it lists 258mA MAX on the spec sheet - that ain't bad

[tubeswell]

... the difference in the FDR (150 mA) and FVR (300mA) PTs.  Has this to do with the difference between what 6V6s and 6L6s need ...?.

Yes

[pdf64]

... the difference in the FDR (150 mA) and FVR (300mA) PTs.  Has this to do with the difference between what 6V6s and 6L6s need ...?.

Yes

The way I see it, it’s not so much ‘what the output valve need’ per se, but rather ‘what current can be drawn through the OT primary impedance?’.
ie at high signal levels, the output valves will shift into their class B area of operation, which will cause the impedance between the active anode and HT supply at the OT CT to fall to 1/4 of its low level, anode to anode value.
So about 1k75 for the DR, about 1k for the VR.
The actual output valve type that happens to be in there is immaterial to that really, any will try to conduct as much current through that impedance as their Vg1=0 anode curve can facilitate.

Hence swapping 6L6 into a DR (or 6550 into a Marshall designed for EL34 or 6L6) can’t appreciably raise the amp’s power output.

[72Blazer]

Thanks,

Honestly-over my head but I'll take note.

Vr
Jim

[pdf64]

Ok, sorry, it boils down to the HT current draw being determined by the circuit, not the valve type.

The valve type determines whether the chosen device will be working happily, or loafing along, or screaming for mercy.

[jordan86]

Ok, sorry, it boils down to the HT current draw being determined by the circuit, not the valve type.

This is well said. I’m only a year ahead of you 72Blazer. For me the realization was that power doesn’t really come from the output tubes as much as it does the transformers. Need big iron for big power. The bigger tubes just “deliver” what the transformers are actually “producing”. Putting big tubes in an amp with small transformers won’t do much for you at all.

[shooter]

It helps(?) to think of the OT primary as a "resistor", the tube as "on or off" so;
ground> on> 4k > 400vdc = ~~~~~ 100mA @ 400vdc
once that's "hardwired"
read up on Inductance, then you can "grasp" how 100mA is somewhat controlled by Frequency
also how inductance reacts to current over time  (This is where the tall weeds grow :)