Hi,
I finished my latest build based on the schematic of Doug>
Doug Circuits
unfortunately the tremolo wasn't working in a periodic way, so I used an OPAMP based LFO.
I reused a cheap transistor cabinet, which was initially loaded with two 6"speakers. I changed the chassis, the speaker, the baffle and the grill cloth.
Now it is loaded with a 10" greenback.
I also made some changes in the schematic to have one half of the 12ax7 as a preamp stage. With the input jacks it's possible to select between EF86, 12ax7, both in parallel or the 12ax7 in series with the EF86.
This last configuration has quite some gain!
Here some pictures:
cheers,
Thomas.
I finished my latest build based on the schematic of Doug>
Doug Circuits
unfortunately the tremolo wasn't working in a periodic way, so I used an OPAMP based LFO.
I reused a cheap transistor cabinet, which was initially loaded with two 6"speakers. I changed the chassis, the speaker, the baffle and the grill cloth.
Now it is loaded with a 10" greenback.
I also made some changes in the schematic to have one half of the 12ax7 as a preamp stage. With the input jacks it's possible to select between EF86, 12ax7, both in parallel or the 12ax7 in series with the EF86.
This last configuration has quite some gain!
Here some pictures:
cheers,
Thomas.
Hi,
I finished my latest build based on the schematic of Doug>
Doug Circuits
unfortunately the tremolo wasn't working in a periodic way, so I used an OPAMP based LFO.
I reused a cheap transistor cabinet, which was initially loaded with two 6"speakers. I changed the chassis, the speaker, the baffle and the grill cloth.
Now it is loaded with a 10" greenback.
I also made some changes in the schematic to have one half of the 12ax7 as a preamp stage. With the input jacks it's possible to select between EF86, 12ax7, both in parallel or the 12ax7 in series with the EF86.
This last configuration has quite some gain!
Here some pictures:
cheers,
Thomas.
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Hi, Sorry to be joining this thread so late in the game. I only just saw it now, and it reminded me of a very similar project I worked out a while back. I came up with a very similar idea that would be, and offer something different; not unique, but not the usual stuff.
I spent many weeks going over the idea generally, and how to specifically work it out. And even more time looking for any possible ways I might just be making a bomb!
I didn't go to the full versatility that this circuit offers (very cool). But kept it rather simple while giving a little something more that usual.
I went with a simpler circuit and a SINGLE input for the very reason this exact amp might scare me a little bit.......
What would happen if someone, who didn't know any better, decided to plug into multiple jacks? Or jumper them as we often do with this input layout?
With no real attempt to trace out all the possible combinations of crossed circuits that one could try, I just decided to keep it simple and just make it sound really good with what it can do.
But kudos (however belated) for this creative approach and completed realization. Very cool. :-D
That is a good point, I haven't thought that someone might use a jumper.
Worst case scenario there will be no sound.
Best case it will have the lowest gain setting (only the upper 12ax7 triode is directly connected to the following stage) and the other circuits will be disconnected by the switched jacks.
I could achieve the same with switches, but I like the look of the panel with the four inputs. Reminds me of older amps.
Still, you are right, one cannot sell something like this and expect the users to behave accordingly.
Worst case scenario there will be no sound.
Best case it will have the lowest gain setting (only the upper 12ax7 triode is directly connected to the following stage) and the other circuits will be disconnected by the switched jacks.
I could achieve the same with switches, but I like the look of the panel with the four inputs. Reminds me of older amps.
Still, you are right, one cannot sell something like this and expect the users to behave accordingly.
From a marketing/sales perspective; if one was going to offer amps like this that can offer many different preamp combinations, it might
work out best to offer different models that could each blend fewer combinations based on which pairings of preamp circuits might play best
together. Clearly, this defeats the idea of having so many options in one package. But again, this would be about the 'selling' end of the
situation.
Many things we buy have a variety of features, and could easily be made to offer a lot of those features all in one version of such a product.
But that would raise the price - and - by using the features to create a few versions means you have more models to offer giving the buyer
more clear options they can use and afford.
For personal use, we can design, combine, break rules as we wish. I have a few items I've built, each one is the exact design and tone I want.
Depending on the moment, of course.
I still like your concept, though.
work out best to offer different models that could each blend fewer combinations based on which pairings of preamp circuits might play best
together. Clearly, this defeats the idea of having so many options in one package. But again, this would be about the 'selling' end of the
situation.
Many things we buy have a variety of features, and could easily be made to offer a lot of those features all in one version of such a product.
But that would raise the price - and - by using the features to create a few versions means you have more models to offer giving the buyer
more clear options they can use and afford.
For personal use, we can design, combine, break rules as we wish. I have a few items I've built, each one is the exact design and tone I want.
Depending on the moment, of course.
I still like your concept, though.