modestmeowth
New member
What are peoples opinions of combining two kits in a custom case to get a duel mono design like that of the Dark Voice 339?
Combining two Cracks
- Thread starter modestmeowth
- Start date
Paul Joppa
Moderator
Haha - my thought is a complete redesign with shunt regulated stages (converting the unused channel to shunt regulator duty in each amp). Completely unrealistic and over the top of course!
It's doable, but you have some tough decisions to make. We are not all that in love with the sound of paralleled triodes, so you may actually end up with better results from just having two power transformers and one output tube. If you build the custom chassis with these questions in mind, you could try out a lot of different designs and pick the one that works best for you.
The shunt regulated Crack is something we have built, but it's more complicated than 2 Cracks in one box, more like a BeePre with two Speedballs.
-PB
The shunt regulated Crack is something we have built, but it's more complicated than 2 Cracks in one box, more like a BeePre with two Speedballs.
-PB
modestmeowth
New member
Caucasian Blackplate said:
How would one go about adding a second transformer? Thanks!
modestmeowth said:
You'd need a chassis plate that would take two power transformers.
Nah, you can just split everything in terms of high voltage. One B+ rail for the left channel, one B+ rail for the right channel, running both grounds up to T3.
I might back up here and ask what is intended to be gained by the dual mono setup? It's usually done to reduce crosstalk and improve imaging. But headphone guys often want more crosstalk, even going out of their way to make crossfeed circuits, and imaging is not a forte of headphones in general. So it might not be that fruitful.
mcandmar
New member
That is curious as it looks like both sides of the outputs tubes are joined together and running in parallel. I assume that would double the power and half the output impedance?
For a Crack wouldn't it be easier to switch to tubes with better separation. e.g. 6CG7 & 7236, or just buy a S.E.X. amp
For a Crack wouldn't it be easier to switch to tubes with better separation. e.g. 6CG7 & 7236, or just buy a S.E.X. amp
modestmeowth
New member
Doc B. said:
My hearing is impaired in my right ear so things always sound unbalanced and I was reading that running an amp that was dual mono would fix that.
modestmeowth
New member
Could you explain that for me? I was under the impression that running dual mono would allow me to adjust left and right independently.Doc B. said:
A balance control adjusts the relative levels of the left and right channel.
"Running dual mono" can mean a lot of different things, but primarily would refer to independent power supplies for a left and right channel.
If you have the ability to drill a couple extra holes in your Crack chassis, you can add a balance pot pretty easily. If you know how many dB of attenuation you need on the left ear, you could build that into your amp for about 15 cents.
"Running dual mono" can mean a lot of different things, but primarily would refer to independent power supplies for a left and right channel.
If you have the ability to drill a couple extra holes in your Crack chassis, you can add a balance pot pretty easily. If you know how many dB of attenuation you need on the left ear, you could build that into your amp for about 15 cents.
Yes, we were under the assumption that you meant dual mono as in two independent amplifier circuits. I see now that you mean a separate left and right volume control. Either separate controls or a balance control would work. Either way could be implemented with one more hole in the chassis, or you could put the balance pot in a separate box ahead of the Crack.
Paul Joppa
Moderator
Dual concentric pots also exist. The only ones I found easily are 500K but should work. The inner shaft is small and goes through the larger outer shaft, allowing each section to be adjusted independently. They are available from many guitar part vendors, along with suitable knobs. Fits in place of the current control, wired up the same. I could not quickly verify that they have an audio (logarithmic) taper but even if they don't some faking can be done with a couple resistors.
Just another option.
Just another option.
modestmeowth
New member
Paul Joppa said:
Thank you all!! How hard is it to wire a dual cencentric pot?
Grainger49
New member
The lugs are much the same as the stock pot. There are actually 2 pots stacked on each other. So is the stock pot but it only has one shaft.
modestmeowth said:
As the quote that you replied to states, it drops into the same hole as the stock pot, and wires up the same. (But you'll need a different set of knobs)
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