Sound City 50 R PA to Express
Moderators: pompeiisneaks, Colossal
Sound City 50 R PA to Express
I picked up this Sound City 50R PA Head thinking it may be a good candidate to make a Trainwreck Express Type Amp. I would gut a majority of it & ditch the solid state pre amp section. I would like to keep the Pull Reverb, Master Volume & obviously the Partridge Transformers. Am I wasting my time or is it a good start?
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Re: Sound City 50 R PA to Express
A trainwreck Express is the last thing I would build this great platform into.
I would just choose a power section and then mod each channel for different circuits much like I did with a Fender PA 100.
Mark
I would just choose a power section and then mod each channel for different circuits much like I did with a Fender PA 100.
Mark
Re: Sound City 50 R PA to Express
I can't make any claims as to its authenticity, but I like the looks of this schematic and how it gets 4 channels out of 4 preamp tubes.
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pompeiisneaks
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Re: Sound City 50 R PA to Express
I'm about to work on a Vh4 this weekend
it's getting some ugly notes and its like 30 years old, so I'll be doing a recap, and double checking anything else I can see. ~Phil
tUber Nerd!
Re: Sound City 50 R PA to Express
That's kinda tough.
On the positive side, you have a roughly 50 watt tube power section and the iron that goes with that.
On the other, the SS preamp to me makes me wonder how much current the power transformer can handle in regards to heater current and high voltage secondary.
Now, a few preamp tubes doesn't draw much in the way of current. Figure 300ma a tube for heater current. I think you could probably measure the diameter of the heater wires coming off the power transformer and calculate that.
That chassis doesn't seem to have much space for a tube circuit either. An Express amp is real particular about it's layout. I think it would be hard to make that work here.
If it were me, I'd pull the transformers and use them in a build. Scavenge the pots and hardware from that unit.
Or maybe fix the unit and sell it?
Sent from my Moto G (4) using Tapatalk
On the positive side, you have a roughly 50 watt tube power section and the iron that goes with that.
On the other, the SS preamp to me makes me wonder how much current the power transformer can handle in regards to heater current and high voltage secondary.
Now, a few preamp tubes doesn't draw much in the way of current. Figure 300ma a tube for heater current. I think you could probably measure the diameter of the heater wires coming off the power transformer and calculate that.
That chassis doesn't seem to have much space for a tube circuit either. An Express amp is real particular about it's layout. I think it would be hard to make that work here.
If it were me, I'd pull the transformers and use them in a build. Scavenge the pots and hardware from that unit.
Or maybe fix the unit and sell it?
Sent from my Moto G (4) using Tapatalk
Re: Sound City 50 R PA to Express
Thank You! You Talked Me Down Off The Ledge. Would I be better off doing a 50W 1968 Plexi Build with the trannys?dbeasley wrote: ↑Sun Jun 03, 2018 3:18 am That's kinda tough.
On the positive side, you have a roughly 50 watt tube power section and the iron that goes with that.
On the other, the SS preamp to me makes me wonder how much current the power transformer can handle in regards to heater current and high voltage secondary.
Now, a few preamp tubes doesn't draw much in the way of current. Figure 300ma a tube for heater current. I think you could probably measure the diameter of the heater wires coming off the power transformer and calculate that.
That chassis doesn't seem to have much space for a tube circuit either. An Express amp is real particular about it's layout. I think it would be hard to make that work here.
If it were me, I'd pull the transformers and use them in a build. Scavenge the pots and hardware from that unit.
Or maybe fix the unit and sell it?
Sent from my Moto G (4) using Tapatalk
Re: Sound City 50 R PA to Express
Sky is the limit really. I reckon you could get away with 3 preamp tubes plus power amp so yeah a plexi could work fine, Trainwreck would work too in a better chassis.
You could also take measurements and have a chassis made to fit your Sound City cab. Would save you from having to get a head cab built.
Sent from my Moto G (4) using Tapatalk
You could also take measurements and have a chassis made to fit your Sound City cab. Would save you from having to get a head cab built.
Sent from my Moto G (4) using Tapatalk
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norburybrook
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Re: Sound City 50 R PA to Express
those transformers can sound amazing. I agree with the above poster and say either do a plexi or an express with what you can salvage from there. Transformers are expensive these days so quality iron like this is a great find if you got this amp cheap.
I made an express last year and didn't follow the transformer placements, I just put them where they'd fit. Had zero issues with it, sounded immense, it was to much for me so I sold it.
It's British iron so I'd go with the plexi, I think it's a more usable amp in most situations.
M
I made an express last year and didn't follow the transformer placements, I just put them where they'd fit. Had zero issues with it, sounded immense, it was to much for me so I sold it.
It's British iron so I'd go with the plexi, I think it's a more usable amp in most situations.
M