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Here is what I've got at this moment!))

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I done my tube di pcb based on schematics in this thread with minor changes. But when unit was build I found couple mistakes on pcb, so now it's in recast. As there was a mistake on that version of pcb, so I just make a signal circuit p2p separately and use pcb as power supply only.

Output transformer is a custom made and sounds very very close to the huge 2kilogram edcor CXSE25-600-5K that I used in my first build.
 
Garry do you still plan on making up pcb's for this project?  I was planning on making up some of my own for myself as I want to learn eagle anyways, but will learn on a different project if you are going to make them.

Thanks!
 
Any thoughts on adding an Ampeg B15N tone stack to the DI?  Perhaps making it switchable? I haven't seen something like that on a DI, so I'm wondering if this isn't the right place in the signal chain for a tone stack.
 
Hmm, not a bad idea. Or perhaps a 25uF cap like a lot of other guitar amps? I'm just looking for another step closer to a B15 tone. I'm considering building this PTP. The parts cost to add the tone stack won't be much. I just wonder if there will be too much signal loss by putting it in this circuit.
 
CJ said:
a simple yet effective tone control is to put a switch on the cathode bypass cap,

switched in for bass
switched out for guitar

I have been looking into adding a cathode bypass adjustment as I am currently building this project.  I am going to add a pot to both bypass cap circuits, and was wondering if there is a way to calculate the best value for the variable pot, best meaning a full tone sweep between no capacitance and full capacitance on the 470uf cap with minimal wasted turn space on the pot.  Would you just start at a 1m pot and work your way down?  Pardon my sketch:
fApczPW.jpg


Thanks for any help
 
SirCVH said:
CJ said:
a simple yet effective tone control is to put a switch on the cathode bypass cap,

switched in for bass
switched out for guitar

I have been looking into adding a cathode bypass adjustment as I am currently building this project.  I am going to add a pot to both bypass cap circuits, and was wondering if there is a way to calculate the best value for the variable pot, best meaning a full tone sweep between no capacitance and full capacitance on the 470uf cap with minimal wasted turn space on the pot.  Would you just start at a 1m pot and work your way down?  Pardon my sketch:
fApczPW.jpg


Thanks for any help
The main effect of modifying the cathode bypass is changing the gain. Don't expect any spectacular change in tone. Using a pot in this position is very subtle. For a typical 12AX7 input stage, the variation would be about 5dB.
That may be different with a much lower value of the capacitor (0.047-1uF), the minimum resistance position of the pot giving a significant HF rise.
With a 220r cath res, a 1Meg pot will behave exactly like a switch, nothing for 99% of the rotation and a rather moderate change on the remaining 1%.
I would use a pot value about 5-10 times the cath res. A rev Log taper would be recommended (or a standard log taper, but the maximum effect will be in the CCW position). Lin taper will definitely be cramped at one end.
 
abbey road d enfer said:
The main effect of modifying the cathode bypass is changing the gain. Don't expect any spectacular change in tone. Using a pot in this position is very subtle. For a typical 12AX7 input stage, the variation would be about 5dB.
That may be different with a much lower value of the capacitor (0.047-1uF), the minimum resistance position of the pot giving a significant HF rise.
With a 220r cath res, a 1Meg pot will behave exactly like a switch, nothing for 99% of the rotation and a rather moderate change on the remaining 1%.
I would use a pot value about 5-10 times the cath res. A rev Log taper would be recommended (or a standard log taper, but the maximum effect will be in the CCW position). Lin taper will definitely be cramped at one end.

I see, thank you for your feedback, I really appreciate it.  If the impact is this subtle in this application, I will probably just stick with a switch and call it good.  Thanks!
 
you can combine both cathode caps into one big one, and use a single cathode resistor

makes wiring the cathode circuit easier and installing the switch easier also,

divide cathode resistor by 2 if using one resistor,

you can really hear the difference with the switch in or out at the low freqs,
 

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