More Transformer Maddness

[Zemaitis]

All this talk of transformers and spec's got me thinking... So I went and dug out my old Leslie 102 amplifier. The power trannie looks good for a 36 watt, it was powering 8 EL84's and 4 12AU7's, there are 2 output trannies each coming off of a pair of EL84... might be good for a couple of 18 watters the are marked Leslie 100-12. Also a couple of chokes marked Leslie 102-12.

Any thoughts on this ?

Schematic here: http://www.geckoamps.com/magnatone109/leslie-101.png

[dartanion]

If the PT was powering 8 7189 (I hope you kept those!!) you could do a 72 watter for something totally new Not sure what kind of voltages were going on there, but a 33ohm Rk on the 7189s seems a bit drastic and would run very hot!!! Unless its a low voltage PT.

It looks like a single gain stage with local NFB feeding a concertina PI, then hitting the 7189s. Kind of a 5E3 type deal without the interactive channels + NFB on the gain stage.

[Zemaitis]

Thank you for the reply... yes I kept the tubes. At first the numbers threw me off... but I knew there was a reason that I should keep them... so they have spent the last few years boxed up and safe.

[dartanion]

Is the unit functional? If so, I would fire it up and start taking some voltages. Obviously with the speaker or dummy load plugged in. This will give you a better idea of what you can achieve with this PT.

What are the 7189s? No codes? Photos? Those could be some killer tubes! They're a heavy duty 6BQ5.[/i]

[zaphod_phil]

I've got a small Leslie reverb amp in my junk pile. It had a pair of 7189As, IIRC running somewhere above 400V, with a 12AU7 PI and transistor preamp. Also a gas discharge voltage regulator tube for the screen grids and PI. Someone had swapped out the 7189As for a pair of EL84s in the past. I'm pretty sure they must be shot. One of these days, I will have to get it built into something useful...