Wreck Songwriter Group Build Discussion

[ToneMerc]

So what's the consensus regarding the PT voltages for these circuits, 245, 250 or 260? Off the top of my head HT current of 170-190mA at a 75% duty rating would be plenty to support them.

TM

[Blackburn]

260v. Loaded rectified voltage is stated at 324v.

[Mark]

The links which may assist discussion.

http://ampgarage.com/forum/viewtopic.ph ... =dongbiter

http://ampgarage.com/forum/viewtopic.ph ... songwriter

http://ampgarage.com/forum/viewtopic.ph ... songwriter

http://ampgarage.com/forum/viewtopic.ph ... er&start=0

http://ampgarage.com/forum/viewtopic.ph ... songwriter

http://ampgarage.com/forum/viewtopic.ph ... songwriter

Provided the output stage is the standard AC-30 type, the higher the B+ the brighter the amp and the harder it is on the output tubes. Perhaps shoot for a lower B+ And use a larger bias resistor value 68 ohms to 80 ohms (I bought wire wound adjustable types on eBay) this would go easier on the output tubes.

[M Fowler]

I'm not sure what the Songwriter 30 uses currently for transformers but I have a note that the Constellation from which the first Songwriters were built off of used:

The constellation uses a 250-0-250 sec. PT and a 4.8K OT
Choke is Mercury Magnetics Choke, JT45C-7H

[RJ Guitars]

260v. Loaded rectified voltage is stated at 324v.

Sounds like you might have a different document than i do... i have something that appears to be the real deal and it gives 260-0-260 with no load, 353v no load (324v loaded) going into the choke. I'll post up a schematic with voltages once i have a chance to redraw it. What i have puts the power supply and dropping string values right on top of the early Rocket builds... maybe a few volts high due to the SS rectifier now that i think about it a bit... no surprise since it is just the the other channel of an AC-30, Kens favorite amp.

Did you All notice the OT is offset of centerline from the PT? He apparently did this on purpose? I am playing with transformers on the bench top to see if this will cause a hum... stay tuned.

I plan to use an Edcor PT, 252-0-252 loaded should hit the schematic values about right. For the OT i am planning a Heyboer HTS-8093-1. I havent devided on choke yet but i'd be inclined to go with the AC-30 standard 15H at around 375 ohms. A 7H choke would open up a lot of options... what do you guys think?

[kwijabo]

rj i'm going to use an extra pacific express PT i have, so it should be 250-0-250. for an output i have the MM a470s from you i haven't put in a build yet. i don't have a 7H or 15H choke around, so i'l probably end up buying a 7H marshall choke.

[hans-jörg]

260v. Loaded rectified voltage is stated at 324v.

Did you All notice the OT is offset of centerline from the PT? He apparently did this on purpose? I am playing with transformers on the bench top to see if this will cause a hum... stay tuned.

quote]

Hi,
I guess a simple reason: he used some holes from a probably former OT. Less drilling
I would try this at least if there is no additional hum.

Hans-Jörg