Nobel Bass Di clone or Alembic F2-B?

[Spencerleehorton]

Turret boards done, now to wind a 12:1 txf!!

 

[Spencerleehorton]

Have wound the 12:1 txf and wired it all up, time to test!!

 

[Spencerleehorton]

Nearly there now, will test on next free day.

 

[Spencerleehorton]

I have got the noble di working now but I seem to have some distortion when I play hard and have the mid and low eq up high.
My heater voltage is a bit high need to lower a bit, got a 1.5ohm 3w resistor coming to drop it to 6.3v

 

[Lekky]

Nice!
The distortion could be related to B+ supply voltage, how the gain stages are biased and so forth. I built an Ampeg SVTDI-based tube DI box recently, but with around 130V B+ voltage. Had problems with distortion when playing hard. Tried various alternative cathode resistor values and found a combination that gave more headroom.
You could try changing cathode resistors or maybe removing cathode bypass caps and see if you get more clean headroom.

 

[Spencerleehorton]

Here is me initially messing around with it, sorry about the long winded video!!

 

[Spencerleehorton]

Really happy with the tweaks so far, going to try a few more tweaks but happy with it so far now I’ve changed the jazz pick-up for a MEC active pick-up, will probably change the p bass pickups for something else as when I have the jazz pick-up volume up and roll in the p bass pickups I get bottom end cut?

 

[Spencerleehorton]

this is what ive settled on so far

@ diode bridge = 370v
B+ = 305.8v
100k/33k = 75.9v
heaters = 6.3v

V1 = 12AX7
Pin 1 = 175.1v
Pin 3/8 = 1.13v
Pin 6 = 182.9v

V2 = 12AU7
Pin 1 = 243v
Pin 3 = 154.8v
Pin 6 = 149.7v
Pin 8 = 5.17v

 

[alexadilardi]

Hi All,

Just completed a Reddi tube bass di clone and it sounds rather nice, was also interested in building a Nobel bass di which uses two tubes and has bass and treble pots and a low cut switch.
Can’t see any schematics online so far so thought I’d ask here to see if this build or something fairly similar was possible.
I think it uses the 5963 tubes? Which I think is a variant of the 12AU7?
Also thinking about a Alembic F2-B
Any info would be appreciated.

Could you provide any schematics for the REDDI clone you made? And which output transformer did you choose?

Sorry if this isn't the right place for my question, but all threads I've found regarding the REDDI are quite confusing

 

[Spencerleehorton]

I wound my own txf for the REDDI and consulted with CJ about it, schematics are all online and my thread should feature all info.

 

[alexadilardi]

Thank you so much!

 

[jonasnoble]

I wound my own txf for the REDDI and consulted with CJ about it, schematics are all online and my thread should feature all info.

How much iron did you use for the txf?

 

[Spencerleehorton]

I wound a special txf which is similar to CJs version, works well for me.

 

[jonasnoble]

I wound a special txf which is similar to CJs version, works well for me.

You won't tell me what lams or how thick you stacked them?

 

[Spencerleehorton]

Here is my thread:

https://groupdiy.com/threads/bass-di-zod-reddi.83686/
it’s not that I won’t tell you at all, I’ve just got in from a 12 hour shift and I don’t have the time at the moment

 

[jonasnoble]

My output transformers came from Cinemag. They are much smaller than I was expecting, I doubt they'll do what I need them to. But I'm experimenting, so it's fine. At least I will learn what doesn't work, and why.

Ordered a comparable Edcor for <1/2 the price of the Cinemags. I want to measure and listen to them side by side. I also ordered a few bobbins and end bells, to wind a couple bigger ones on my own. I pretty much gleaned the specs (as much as I could) from reading CJ's old threads. I'm still missing some vital information. Luckily, I have "experiment" money, which had been set aside for purchasing some of his custom winds.