Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: dude on June 29, 2020, 12:34:03 pm
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I have an older Leslie OT, (#100-12) upright, all gray, looks about 20/25 watts PP, looked it up: 9.4K primary, 16 ohm secondary. Are these any good tone-wise for a pair of EL84's running 16 ohms, say 18 watt amp? 16 ohms is the issue for me (I'm loaded with single 8 ohms speakers), what about 6V6's with 8 ohms on the 16 sec. (about 5K primary?) Interested in what they sound like tone-wise.
Running 8 ohms Primary is about 5K, good for 6L6's in PP (I guess it's too small for 6L6's).
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ran a pair of 6L6's at 8W, sounded great
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a pair of 6L6G/GB/GC/5881 with about 360V to plates with 9K load should sound nice. would make about 25W.
--pete
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I think he wants a 4.7k condition so he can use the 9.4k:16 with an 8 ohm load.
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then run fixed bias. 5K works as well - or - run 2 x 8Ω drivers in series.
--pete
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Yes, want single 12 (8 ohms) 6L6's, PP, maybe something like a Sluckey's Deluxe Lite but with the bigger bottles, fixed bias with the Leslie OT's 16 ohm sec. running the single 8 ohm, 4.7K primary, around 360 on the plates... that OT look pretty beefy probably 25 watts, l'll give that a shot. Still have five or six Hammond A0-43's with iron, just add a plate for the sockets and use the 5U4, should be around 360/370 on the plates. I just read some data about that Leslie OT is made for hifi applications, but l can always swap it out. Thanks
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That AO-43 PT is most likely too light weight for 6L6s.
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i have run 6v6s pp at 5k to 8ohm as well as single ended and it sounds fine. but you could also run a pair of 6L6 at like 15 watts on that 5K to 8 using a 5y3 at 300 to 325v and that sounds good too. i have a kodak projector that was set to run 6L6s pp with 2 5755s and that is actually my favorite amp , very freakin loud but it has 3 gain stages and a split phase inverter. used to have 12ax7s but it had no headroom. the 2 nos raytheon 5755s were the ticket. this is not my project but i have the identical projector which i had to change up the input and preamp stages a bit . sounds alot like a tweed super.
https://imgur.com/a/RnCnE
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I’ve been running 5881 with that AO-43 PT for a good while, no issues, not even warm. 6L6s and slightly warm to the touch after an hour of hard playing, EL34’s a little warmer than with 6L6’s but only after over an hour of hard playing. Can’t find much spec wise on that PT except a list of the tubes it ran in it’s original organ format. It was made to run EL84’s and EL34’s draw a lot more current but seems to hold up, so far. So, from my experience probably ok with 6L6s but probably pushing it with EL34s. Running Doug’s 6v6 Plexi.