Lowery LC1 B 6550 PP organ amplifiers.

[Mike Stehr]

Has anyone ever dealt with any organ amplifiers using this topology, or this particular brand/model?
A schematic would be a real bonus, it would be nice not to retrace the damn circuit and draw one.

6550 PP amp, 5AR4 rectifier with a 6V6 screen regulator. 6SN7 driver.

My first attempt at high wattage tubes with Klipsch Cornwalls, I think it should be enough.
This is gonna be a intense project......


Mike Stehr.

 

[Rockmonton]

well you dont have to worry much on modifying the output stage the whole idea of making it ideal for Hifi is to design a good solid preamp stage and have decent accurate parts in the rest of it....... i'd say if it works, play around with the preamp stages as these organs had to have really good frequency ranges

 

[Mike Stehr]

One works, not optimum, but works. The other is a basket, but everything is there and the PS xformer and OPT measure fine.

The PS transformer has around 470 volts on each leg, with the plates at 600 volts and screens at around 295.

So to get to 400, 450 volts on the secondary to try various output tubes, it would take a choke input PS filter to drop the voltage down.
It is a CLC setup currently, and I don't have chokes to use for inputs of the supplys.
The audio friend I purchased these from threw in some little transformers to use for a negative bias supply for the output tubes.
With a pair of 50k pots to tweak bias, that's about it for output stage for now I guess.

You called it though, the working amp was on the bench and the 6SN7 gain/inverter stage didn't seem up to snuff to get proper output.
(There could be numerous other reasons, however.)

The thought of using the Magnavox paraphase inverter driver circuit using the 6SN7 has been pondered......the whole project is in the reverse engineer, ponder and upgrade stage.

 

[prohall]

Hi Mike, yeah i know old post.. , but was wondering how you made out with that lowrey amp. Looking to posibly pick one up to convert to a bass amp and still not much info availbe on these. Was wondering what secondary taps were available on that OT?

Pete

 

[fingers5]

Hi, Pete. I know old post but just saw it. I have access to a Lowrey LC-1B. It's been in storage and the lady wants it and the organ gone. How did yours sound as a bass amp?