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Leslie 125 - Printable Version

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Leslie 125 - TV MAN - 10-26-2020

Hey all, my first project after a seemingly endless season of mowing. It's a Leslie 125 amp. Pretty simple. Ebay find. I ordered a can cap for the sake of simplicity (I thought) from AES, described for this amp. I am actually trying to build something for an electronic drum set and bass guitar, thought this might be ideal with the hefty 6L6GC outputs. So, I got a few free hours last night and did the recap. I slowly powered things up and it sounded ok, not HiFi, but its for a musical instrument. Originally from a Leslie speaker. I was satisfied and powered up direct to get a feel for it. Well, I heard a bunch of cracking and buzzing (I thought) from the power transformer. I thought I would take things apart and verify before scrapping the project. After stripping the covers off the transformer, I powered back up and found the noises coming from the new can cap! I was THRILLED! It WASNT the PT! So I put things back together and stuck the old cap back in and it sounded fine. Must be a defective can. So Im trying to exchange. The voltage shoots up to ver 500 before it drops back to around 425, so this 475v cap may not be up to the task. Even though the description says its for a Leslie. 

When I got this amp, I was shocked by the small size of the output transformer, looks like about a 15w tranny. I thought I would see a larger trans. I dont think this will have the power to drive a 15" sub like I want. I haven't tried it tho. Looks like the power trans is pretty heavy, B+ seems adequate, so I'm considering switching to a larger "orphaned" transformer. Any thoughts on all this?

Here's a few pics of the project at hand:

   
   
   
   

RE: Leslie 125 - rfeenstra - 10-26-2020

I believe this amp is only rated at 20 watts. The 125 leslie was a low power unit with only 1 rotating speaker, not the horn and drum.. I believe the woofer was a 12". I used to work on a lot of leslies. Most of the higher power units used 6550 outputs. I'd hate to count the number of red plating Leslie speaker amps I've repaired! Many years ago, though. I still have a couple of sets of 6550's left from those days.

RE: Leslie 125 - TV MAN - 10-27-2020

Thanks Ron, it's a little more power than I presumed. I'm going to try it and see how it performs. If I'm not happy with it, I'll try a different trans or just build a simple power amp. I recall this amp from my youth - my mom played the organ. She had an early 1960's Lowrey and Leslie speaker that used this amp. She would play, I would lay where I could see the tubes lit up and listen. A strange but fond memory. She passed way too young. 56 years. Anyway, this amp caught my attention. Do you recall the main cause for red plating?

RE: Leslie 125 - rfeenstra - 10-27-2020

Boy, that was a long time ago. But, I suspect it was the coupling caps turning leaky upsetting the bias. I know I used to carry a supply of orange drops for just such applications. I see you've already changed those caps!

RE: Leslie 125 - TV MAN - 12-03-2020

I got to playing around with the amp. It doesn't do too bad, but I'd still rate it at a lower power. If I push it too hard, it will clip. I just purchased a small mixing board with tone controls and all, but it has a pretty low output, so I have to crank my bass guitar. I found a 35w PA amp at an antique store, 5 channel. It will shake the room when I get to plucking. I need to recap, but it works pretty good. Basically uses what looks like the modern version of the 7591a tube. I imagine I'll end up using this Leslie for a smaller powered sub on our TV. Just for kicks and grins of course.