6BM8 tubes... what to use them for!

[Bruce / Mission Amps]

" My main concern is that will the 12AX7s have enough gain to smash the 6BM8 Pentodes"


Are you going to drive the 6BM8's pentodes with 12AX7's or the triode inside the 6BM8? As I understand it the 6BM8is a triode/pentode.

http://s28.photobucket.com/albums/c2...nt=LWR-MTS.gif

As a side note, with humbuckers ......... I can get incredibly clear ongoing sustain/overdrive with this amp. I can hit a note and hold it til it feedbacks. My Little Wing Reverb sounds fairly similar to the sound clip of DaGeezer's Little Wing. Although the guy who did that clip is a much better player than I will ever be.

With respect, Tubenit

Yes, the 12aX7 will be the preamp tube.
The triodes in each 6BM8 will be the triode that drives that tube if a LTP... or if a cathodyne driver then one 6BM8 triode will drive the cathodyne, which will be the other triode of the 6BM8.

The chassis I have is so small, 5 nine pin sockets is totally out....I don't think I can get even one more 9 pin socket in so reverb is not happening in this one..

[Alex/Tubewonder]

Here's a cool take on a 6BM8 SE

Hey Bruce,
how's you 6BM8 project going? Can you hear any differences between NOS 6BM8 and current production stuff?
To my old ears they sound very very close.

To be true to the topic title (6BM8 tubes - what to use them for) - here it goes:
Myself and another pretty well known Swedish designer - it should be is easy to identify him once you've watched the vids) - have been working on collaborative project involving 6BM8 tube since summer 2007. The result was premiered on May 10-11 at the FUZZ Guitar Show here in Gothenburg.



It's a hybrid with solid state discrete (no opamps) preamp, goes from NEAT to OTR (On The Rocks), toggle on top adds rocks to the neat whiskey in the jar.

"Louder" knob does what its name suggests.
"&" knob operates on edges of the "rocks" smoothing them out or roughing up.

"More" knob is, if I may say so myself, a real innovation in tube amp circuits.
You've seen the Triode/Pentode or Triode/UL/Pentode switching arrangements before.
This does "More". Operating mode of the power tube is continuously variable between triode and pentode with varying degrees of UL mode in between. Besides the obvious reduction of available output power in triode mode it also provides some presence/edge boost as the knob is turned more towards UL/pentode modes.
Output Power in pentode mode is ca 3W, in triode mode drops to about 1W.

No decision yet as to when, if at all, this will be released as a product. We did it just for fun.
The MORE circuit is PAF.

Vids: LouderAndMore

[imaradiostar]

"these go to eleven..." and a half...

jamie

[Natedawg63]

Eagerly awaiting your final layout Bruce... Been looking for a low-watt ECL82 layout.

Nate

[Bruce / Mission Amps]

Eagerly awaiting your final layout Bruce... Been looking for a low-watt ECL82 layout.

Nate

I've been working a little bit with this project off line with Jeff... tubenit ... and other then some minor tweaking to fit my chassis, actual working parts values and combine it with a layout I already started, he has a nice layout going so it shouldn't be to long before I can get it in high gear.

[Natedawg63]

Bruce... Don't know if this may help any... I am not a amp expert, just a amateur fan... I ran across this while looking up 6BM8 guitar amps.

It is a 60's Swedish amp @ 9w which uses 4 tubes including a EZ80 rectifier, 12AX7 driving 2 6BM8's. Thought it may be of some interest, maybe not...

http://www.hagstrom.org.uk/Schematic...0schematic.jpg

http://www.haskinshagstroms.com/John...sub_section=24

http://www.hagstrom.org.uk/hagstrom_amps.htm

Cheers...
Nate

[Bruce / Mission Amps]

Bruce... Don't know if this may help any... I am not a amp expert, just a amateur fan... I ran across this while looking up 6BM8 guitar amps.

It is a 60's Swedish amp @ 9w which uses 4 tubes including a EZ80 rectifier, 12AX7 driving 2 6BM8's. Thought it may be of some interest, maybe not...

http://www.hagstrom.org.uk/Schematic...0schematic.jpg

http://www.haskinshagstroms.com/John...sub_section=24

http://www.hagstrom.org.uk/hagstrom_amps.htm

Cheers...
Nate

Thanks Nate... although this little 6BM8 amp project is not one with tremolo, the Hagstrom looks like an easy build.

[Natedawg63]

I bid on and won a cool lil Gibson GA-5T amp on Ebay tonight. It is the very early true Skylark model with tremolo. It is around 6W single ended using a 5Y3GT, 12AX7 and a single 6BM8 for power and tremolo - not foot switched. Not a perfect amp, but pretty clean for being a '59ish model. Problem now is finding a schematic, as Gibson was known for changing up schematics from year to year. I can find the SE 6V6 model, but have yet to come across the SE 6BM8. This may be close to what you guyz are working on Bruce... I have my feelers out for a schematic... will post it if I score one.

Nate

[Enzo]

I posted what I think you need over on www.ampix.org a few minutes ago.

Look for GA1

[Alf]

Pics not available

Enzo,

Thanks for all you contributions on the ampix site but some I can't download .

Are they still available ?

Alf

[Enzo]

A while back, something went funny about the time tboy did something with the system, so some of my AMpix posts from before that time disappeared, though the icons remain. Happened not just to me. I know some are missing, but I don't have time to download all of them myself to find out which ones. If one is posted there and is now missing and you need it, post a note on the forum and I will replace it. Is this current one not working now?

[Alf]

Enzo ,


The current one (Maestro) works fine .
It's a few of the older ones that can't be downloaded like the SWR and the SVT pro.

Alf

[Enzo]

Ah foo, I'll go through them..

[Alf]

Thanks Enzo, but don't hurry, if you happen to come across them that would be nice though.

Regards, Alf

[TheTinMan]

I saw an article online (possibly by Eric Barbour when he was with Svetlana), that used the 6BM8 as a reverb driver in Fenders.

Does anyone have a schematic of this Eric Barbour circuit?

I've found several references to it but can't find the actual drawing.

Thanks in advance.

Bruce - how's your 6BM8 project coming along?

Chip