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6BM8 for reverb duty

marshman
November 23rd, 2010, 12:13 AM
So, I've got a couple of these things and I got to wonderin' what they might be good for. I took a peek at a BF schematic, particularly the reverb 'section' and see a 12AT7 as driver and a triode of 12AX7/7025 for recovery. Any reason I couldn't use the pentode of the 6BM8 for the driver and the triode for recovery? The transformer should be similar if I understand the datasheet correctly, but where would I get the appropriate "B+" from a typical preamp circuit? Would I need some sort of off the wall/custom PT?

I really need to keep my mind on a leash...

celeste
November 23rd, 2010, 07:44 PM
You will likely want more gain on the recovery side, but other then that, it looks like a pretty good single tube solution to tube reverb

tubeswell
November 23rd, 2010, 09:06 PM
The 6BM8 pentode driver will work really well to drive the verb (as will a 6GW8). Use a gapped SE OT with a 5k Pr Z.

marshman
November 24th, 2010, 12:58 AM
I'm glad that I understood the basics. I have never turned the reverb up in any amp over 3, so maybe I'll be OK with it as is. If I ever get around to implementing it, I'll let you folks know how it turns out.

Thanks

celeste
November 25th, 2010, 11:31 AM
It seems you are not the first to think this

http://music-electronics-forum.com/attachments/11600d1289636454-5f1champ6bm8reverb1_0b.png

marshman
November 25th, 2010, 10:08 PM
Very cool, big C, thanks for the link.