peavey deuce transformers what to build

[norburybrook]

Ok,

So I've got a set of peavey transformers from a Deuce VT combo. it had 4 x 6L6's but a solid state pre and fx. here's the power transformer spec;

Peavey_Deuce3a.jpg

So I was wondering what I could build with this.

My wonderland has 4x JJ 6L6's running at 500v just fine from a peavey transformer and full wave Bridge rectifier.

Could I build a #183 and use EL34's and could the 20v secondary be used to power 12v relays if I used half of it i.e the 20-0-20 ?

there's another 56v tap which I presume would be better for the bias anyway.


My last transformer was 195-195 and that made 500v how does a 370-370 make 500 as well?- without a center tap?



cheers

marcus

[bluesbreaker62]

Shouldn’t that actually give you a slightly lower voltage?
You 'only' have 370Vac over that single tap, vs 390 with you other amp.

That should give you about 370*1.41= 522 Vdc (minus a small drop) unloaded.
According to Merlin Blencowe that should give you about 370*1.3= 481 Vdc under fully loaded conditions.

El34’s will pull a little more current than the 6L6GC the amp originally would have come with, but I think you might be OK, they’re plenty beefy transformers.
Impedance might also be a little off.

HAD seemed to have no problem using these transformers in his builds (see #177 below) and does not use any extra transformers for the pre-amp tube heaters or even for the relay power supply (Thought I’m not 100% sure these are VT Classic transformers in this particular amp)

DSC00657.jpg

Dumble 177 Full gut shot.JPG

Hope that helps a little

[norburybrook]

Wow, that's Dumble #177 , those are indeed very similar transformers to my wonderland build and now those from the Deuce. Is there a schematic for this amp?

It looks like HAD has done what I thought might work and used one of the extra secondary's to power the relays

I'm not getting my head around how the voltage rectifying works.

the wonderland build transformers from the triumph were 195-0-195 so a center tapped secondary. I used the two 195's without the center tap and a full wave bridge rectifier which gave around 500v DC

the Deuce transformer has no center tap and 370-370 so how does it get rectified to 500v as well like it shows on the schematic?

if it was 370-0-370 I could understand the regular biphase rectifier but not with a full wave bridge.

sorry if I'm being a bit thick.

edit:

shouldn't the main HT secondary be 370-0? that would make sense

[martin manning]

The Deuce is 370-0, so 370 x 1.414 = 528. The 195-0-195 is 390-0 ignoring the CT, so 1.414 x that is 551.

[norburybrook]

beat me to it Martin.


So in that case would current EL84's be fine at high 400's? and what would be the best way to use the 20-0-20 tap to power relays?

would my idea of 20-0 and a 12v regulator /relays work? can you use half of a secondary like that? I think the regulators can take 35v


Marcus

[martin manning]

20VAC would rectify to around 28VDC, so that would work. What is the primary impedance of the OT? That will be important, as well as adjusting the screen voltage. The simplest approach would be keeping 6L6's.

[norburybrook]

20VAC would rectify to around 28VDC, so that would work. What is the primary impedance of the OT? That will be important, as well as adjusting the screen voltage. The simplest approach would be keeping 6L6's.

yes, I doubt there's a massive difference in 6L6 and EL84 power section. Why does the impedance matter between 6L6 and EL84's? I've noted that EL34 are 3.4k and 6L6 are 5.6k.

I've done a bit of googling and it says about EL34's:

while a quad of EL34s running class AB1 in push–pull typically run anywhere from 425 to 500V plate voltage and produces 100 watts output. This configuration is typically found in guitar amplifiers

How would I measure the primary impedance of the OT I can't find any specs?

M

[dorrisant]

This is the same set I recently posted about... From a Deuce... Don't know why I wrote Dual on them. Hopefully these measurements will be of some use...

[norburybrook]

yes, they're not the same as mine but close. Mine's a Deuce VT, yours might be the original one. I have no center tap and my OT primaries are blue-red-brown.

so it's probably a similar primary impedance then of 2.3K

my 100w Wonderland sounds wonderful (sic) with the peavey iron, really great sounding clean amp so I can recommend these transformers certainly for a clean build


how does that affect 4 EL34's and high 400,maybe 500vDC screens?

or, shall I just build a 4x 6L6? any one care to chime in with differences between 4x EL34's v 6L6's

Marcus

[M Fowler]

More of #177 HRM

Dumble 177 FET.JPG

[norburybrook]

do we know what #177 is?

it has no LNFB and snubbers on V2

I don't know resistor codes well enough to know if the P.I is the bluesmaster type without looking.

has this been documented?


M

[martin manning]

I would get an impedance measurement on the OT. Just put some AC on the primary outer leads and measure that voltage and the voltage across the secondary: . Calculate that ratio, square it, and multiply the result by the specified impedance of the secondary tap you measured. Zpri = (Vpri/Vsec)^2*Zsec Even better if you put the appropriate resistor across the secondary when you do this. EL34's are 17% lower in Pa max than 6L6 so you are reducing the margin. The PT looks pretty stout, so it's not likely to sag much under load like some 100W Plexi's. That will add to the stress on the output tubes.

[Aaron]

do we know what #177 is?

it has no LNFB and snubbers on V2

I don't know resistor codes well enough to know if the P.I is the bluesmaster type without looking.

has this been documented?


M

Hi Marcus,

This amp come up before, but a while back.
Looks like Skyliner Tonestack, PI 1M-470R-1M-18k, GNFB 4k7-390R. Notice the other resistor on V2, looks like 47k or 470k to ground.
And choke resistor.

Aaron

[norburybrook]

@martin,I'm away playing a festival tonight but will do that tomorrow.

@Aaron, it looks like he's reused the peavey choke resistor in that build as well as the transformers.

I've s feeling I may have snipped out that same resistor too for future usage [emoji16]

What difference in sound does using a resistor instead of a choke make ?

Marcus




Sent from my Nexus 6 using Tapatalk

[martin manning]

A choke will get more ripple reduction for less voltage drop, but costs more.