AB763 with 5F6A two channel

[kwijabo]

all...has anyone had experience combining the vibrato channel of a super/deluxe AB763 with one input of the 5F6A? i had some time today so i put a proposed schematic together. this could go 6V6 or 6L6 depending on the PT used.

first, i make no claims its complete or correct. first draft.
second, could deluxe or super iron could work since this has the same amount and type of triodes? actually one less 12AX7 triode since the trem circuit isn't there anymore and the bassman only needs 3 triodes, so i'm thinking yes it could work.

anyone see any issues with this setup? i guess the dwell and tone controls on reverb wouldn't be necessary. could just go stock AB763.

[Roe]

should work fine

[10thTx]

That looks good to me. Any chance that you'd be willing to post the SCH version also, please?

I'd go with iron that allowed the option of either 6V6 or 6L6. I use Hammond PT's on both my amps. Using a 330 ohm/10w resistor, they are cathode biased and I can simply switch between 6V6 & 6L6 tubes with no problems.

With respect, 10thtx

[kwijabo]

here's the SCH file. also, i updated the tube designators, pins, and power supply caps. those were all the same cause copy/pasted and forgot to change them.

yeah, i thought about perhaps making this so it could go either 6V6 or 6L6. classic tone's deluxe reverb PT could work with 6l6's, but i think only if you went with a single channel - that woudl mean not including the 5F6a channel.
http://www.classictone.net/40-18066.pdf

alternatively, their super PT could definitely handle it and does have the lower B+ if 6V6's were desired. but myabe a little too low.
http://www.classictone.net/40-18094.pdf

would probably use an up-right for this to save some space inside the chassis. glad to know classictone makes them!

[10thTx]

Thank you for sharing the SCH schematic!

With respect, 10thtx

[guitardude57]

Seems all the preamp tubes before the PI are all V1 on the Bassman deluxe pdf schemo...

[10thTx]

Here is why I was asking for the SCH schematic.

Couple of more options ....................

Reverb on both channels

Reverb and vibrato


With respect, 10thtx

[10thTx]

OR ..................

You could use dual simulataneous relay switching to go between the two channels.

I tried to factor in caps in series to make the "values" didn't change much. That's the reason for the .47 prior to the relay DPDT.

With respect, 10thtx

[pdf64]

For me, a bassman would be too dark without the added zing of the power amp presence control.
However, 6V6 seem to add brightness (compared to 6L6) so it may pan out fine.
Pete

[Roe]

you could add a presence control and control it with a relay. also, remove the 220k after the bassman eq if you use a relay. finally, some feel the ab763 vibrato channels sounds the best if you have a normal channel connected. it could be that the bassman channel could do the job as well, but in this case you need to change the dpdt switch so that the bassman channel is not dumped to ground when using the ab763 channel

[kwijabo]

woah! i left for a day and come back to this. 10thTx, thanks much for your efforts.

so i had wondered if it was possible to have the two channels share V1. i noticed that the AB763 doesn't have a coupling cap coming off the plate...the tone stack handles that. so i didn't know what the effect would be if you put one there like you did with the 0.47uF.

reverb - forgive me but i have no experience with reverb schematics. how did you come to the value of 150k across R and R2? ive only seen values up in the meg's and i thought decreasing that increases the non-reverb component. and now i see that the AB763 pre-amp has an extra gain stage before the reverb instead of after it. curious how this would affect it.

yes, the presence could be put on a relay, or maybe just wire it in always. could use the 5F6A PI and feedback loop.

after reading your suggestions and a search, i found a thread on this forum about adding reverb to the 5F6a circuit:
https://tubeamparchive.com/viewtopic.ph ... 8f7fad2cf6

also, after a little more searching online i found something very similar:
http://hasserl.com/Amp_Mod_Docs/Fender/ ... _schem.pdf

http://www.youtube.com/watch?v=B4g6GUBudpI

at this point this is just a curiosity thing. probably wouldn't even start this until next year at some point. but i like to think through these things and see what you all think. thanks again everyone.