My take on a Vox hybrid

[dbeasley]

Yeah I keep getting the same HTTP error. I'll try to convert it to a different format.

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[pompeiisneaks]

HTTP error doesn't mean the format is bad, it means something else is wrong. If the file format isn't supported, the board would report the error. The only other thing I can think of would be size? But I think that also reports back that the size is too large. Sounds possible some kind of problem between your home network and the site?

How big is the file?

~Phil

[valveandsound]

I think it will work this time. Im pretty sure this is the correct schematic.

[dbeasley]

Here are some photos of the thing I built that's similar in idea to what you're doing. Using a set of vintage Tube PA iron I get almost 100W in high power mode, 38 watts in low power (switch in low power mode turns off the outer pair of power tubes and runs the inner set cathode bias).

Using a 6BR7 instead of a EF86 for the Pentode channel. Bypassable effects loop (using a Metro Zero Loss loop). I find toggling between two coupling cap values stands up with real gigging and switching between strats, teles and my PRS. I also added a Pentode/triode switch for the 6BR7 channel. It does sound more like the Rocket channel (labeled modern on my amp) but when pushed with a clean boost it's very cool and unique. By itself, very similar sounding to the Rocket channel.

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[valveandsound]

I did make one correction to that schemo that I did not update - I used 820R/22K cathode values for the PI to drive the 6L6s more effectively.

[pdf64]

After getting a friend's AC30 vibrato working properly (and greatly enjoying the effect), an idea that's been on my mind is to re-arrange the layout of a Vox pre-amp, so as to incorporate the top boost stage and vibrato section as bypassable additions to the main signal chain, between channel mixer resistors and LTP input to the power amp.
2 channels, one pentode the other triode.
It may be able to do everything that the regular 3 channel arrangement can, but with a few, previously unavailable, additions
My issue with the regular arrangement being that whilst the vibrato is fantastic, the channel is a bit blah, which I suspect may be largely due to its volume control being at the end of the channel, rather than after the input stage, as is the norm.
I've had a medical upset that's put a spanner in the works for a while, but when I get chemo done with, I'm hoping to test this idea out later in the year.

[joeboo88]

well you get better Pdf64 we're pulling for ya.

dBeasley that's a frikin awesome looking amp!

[Roe]

After getting a friend's AC30 vibrato working properly (and greatly enjoying the effect), an idea that's been on my mind is to re-arrange the layout of a Vox pre-amp, so as to incorporate the top boost stage and vibrato section as bypassable additions to the main signal chain, between channel mixer resistors and LTP input to the power amp.
2 channels, one pentode the other triode.
It may be able to do everything that the regular 3 channel arrangement can, but with a few, previously unavailable, additions
My issue with the regular arrangement being that whilst the vibrato is fantastic, the channel is a bit blah, which I suspect may be largely due to its volume control being at the end of the channel, rather than after the input stage, as is the norm.
I've had a medical upset that's put a spanner in the works for a while, but when I get chemo done with, I'm hoping to test this idea out later in the year.

A much easier solution, that still works well, is to add global bias tremolo to the output stage (ala brownface fenders). This even works with the larmar master volume (that is perfects for amps like these without negative feedback). For the preamp, I added a top boost channel, ef86 channel and a normal channel

[pompeiisneaks]

Thanks all for the input! PDF64 TAKE CARE!

I for one LOVE my tremolo on the AC30 version and do agree the channel with trem off is 'meh' otherwise. The trem is so different from a bias wiggle type. It was stolen from either a wurlizter or hammond organ's schematic, but Dick Denny accidentally dropped a screwdriver in the board and jumped two points on accident and it sounded so great he went and redid the schematic with that jumper and the rest is history. To me that trem sounds like the tremolo used in Bang Bang by Nancy Sinatra. So lush.

That aside, dbeasley, thansk so much! I'm definitely thinking about incorporating your ideas and/or at least having a switchable tone stack in some way so I do get that raw normal channel. That's one of the things I love about my current AC30/4 I built, is that tone. I'm starting to think that adjusting it with the tone stack is a bad idea per your comments.

Thanks.

~Phil

[dbeasley]

I always thought Bang Bang was a Blackface Fender? It has that really sharp Square Wave type tremolo sound. I'm not familiar with the vox trem so I can't say.

Glad it finally uploaded lol. I gotta say, Vox type circuit sounds great with lots of headroom. Maxing out the master and using the volume control like a Non makster volume amp for cleans works great. You can easily dial in the top end to not be icepicky with the cut control. Coincidentally, it also sounds really awesome with a Rhodes or Wurlitzer lol.

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[dbeasley]

Also, for an interesting take on a Pentode circuit look into the Filmosound 385 schematic.

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[lord preset]

Any progress on this build? We still want to know how it turns out

[pompeiisneaks]

after a lot of the feedback I've decided to revisit some of what was mentioned. I've not yet had a chance to retool the schematic, etc. It's on hold for now.

~Phil