i have a set of single ended amp transformers. worth using?

[wsaraceni]

i have a 125DSE output transformer and a 269EX power transformer. What could i make with these? or are these junk and whatever i make should start from scratch. a cool single ended amp using an el84 or a 6v6, solid state rectified, with just a vol or vol/tone would be cool.

[johnny riff]

Hello
I think you could make a nice champ/princeton style amp with the output tranny.but you would need alittle more juice in the power tranny.I think the ex269 specs@190 0 190 which gets you about 260 B+. with SS rect.when you would want 300 + IMO.I built a champ style amp a few years back with el84 output , it's a great sounding little amp.I use it as a practice amp to play along with cd's.

JR

[dave g]

260 volts on the plates is right about where you want to be for a single EL84

[johnny riff]

Yes 260 on the plates would work for a el84,but when I built mine I first got it going on a test bed with adjustable B+ and found I liked the higher B+ about 310/315 with 8vdc on the cathode.I guess it all comes down to taste.I would say if you got the parts build away you've nothing to lose and if you enjoy amp building as much as I you'll only gain.

JR

[LeeMo]

I built a Mini Wreck with a Firezog line output and VVR. See this thread for gutshots and schemo:
http://ampgarage.com/forum/viewtopic.ph ... =miniwreck

Mine sounds really good.

LeeMo

[wsaraceni]

what would be needed to change the champ schematic to use an el84? what about something similar to a mini z. maybe a mini z with tremolo would be cool.

[jimipage]

Hello
I think you could make a nice champ/princeton style amp with the output tranny.but you would need alittle more juice in the power tranny.I think the ex269 specs@190 0 190 which gets you about 260 B+. with SS rect.when you would want 300 + IMO.I built a champ style amp a few years back with el84 output , it's a great sounding little amp.I use it as a practice amp to play along with cd's.

JR

Actually, it would be more like 280VDC :

190(primary)/115(VAC)=1.652
1.652*120(wall voltage)=198.24
198.24*1.414(rectification)=280.311

It would definitely work with a single EL84. However, I like the 269EX for standalone preamps.

[jimipage]

edit

[Voodoo_Man]

Actually, it would be more like 280VDC :

190(primary)/115(VAC)=1.652
1.652*120(wall voltage)=198.24
198.24*1.414(rectification)=280.311

It would definitely work with a single EL84. However, I like the 269EX for standalone preamps.

These are real life readings from one I had.

317VDC with FW Center Tapped Rectification and Capacitor Input (121VAC Supply), No load

God Bless,
John

[Alexo]

The 269EX is a great transformer for single ended 6AQ5 amps - my favorite! You'll probably need to use a 100uf/250R/100uf pi filter before hitting the OT primary though, that's what works for me. 5K load.

[jimipage]

317VDC with FW Center Tapped Rectification and Capacitor Input (121VAC Supply), No load

oops -- forgot to mention mine are real life numbers, too, but with load. I more or less got the same results as you. Thanks for clarifying.

[wsaraceni]

what if i wanted to get a different power transformer for the build and use the existing power transformer for a tube tremolo/tube preamp. kinda like a matchless hotbox and vibrobox in one. would that work? anyone have a schematic of this type of setup

[wsaraceni]

still have this transformer. it looks like it would work great for the mini z. anyone know what the specs are of the transformers in the mini z? i think i have almost ALL the parts lying around to build that if i wanted except for the OT and some of the higher wattage resistors.

[wsaraceni]

i've been wanting to build a single ended amp for a while but haven't found the right stuff. i have a spare fender blues jr transformer. think i could use that with the above OT for a nice single ended el34 amp or something

[Phil_S]

The Blues Jr is a PP amp. OT's are not interchangeable. The SE OT has an air gap to keep it from getting over saturated.

The BJ is a 2x EL84 amp. The OT will probably work fine for EL84, 6V6, 6AQ5 in PP config.