Tube Preamp pedal + DI Output question

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Hi again,
I finally got around to building a proto of this (without the cabsim) and it sounds great :)

Trying to squeeze in the cabsim a question arouse in my head....
Is one schem better or more convenient than the other (output section)?

https://ibb.co/Z2mxV0Hhttps://ibb.co/h2K83n9
Thanks in advance for your advice and suggestions as usual :)
Cheers
Sono
 
I don't know about more convenient but on out2 you don't get the cab sim output at the jack, it only appears at the DI out. Is that what you intended?

Cheers

Ian
 
Thanks for your reply Ian.

Well, that's the question really...originally I thought this as being a pedal that can be used as a preamp stompbox at the input of an amp or as a portable amp easy to carry to a recording session or a gig (for this the XLR output would be used, or even both).

So both outputs should be active at all times and the cabsim switchable on/off. Isn't that so? There is no point really in using the cabsim at the jack output, right?

Cheers
Sono
 
I think you are right. You get the tubey sound from the first stage then the jack feed sit to some power amp and speaker which is a real life cab. Preceding that with another cab sim is not likely to be useful unless you want a real cab fed by a sim of another cab.

Cheers

ian
 
that circuit wants a small output transformer to sound nice, this would also cut down on noise, and if you tap right of of it to run the DI = no more chip to blow up. and a dual secondary (splitter) would mean isolation for the DI. maybe a gnd lift sw and you are set.

8:1 xfmr would be hi fi, but who needs that for a drugged out guitar player. so 4:1 would be a bit of a mis match but tons better than nothing.. gonna need a big cap to drive the xfmr for good bass. like 5 or 10 uf at 400 V. poly would be deluxe! xfmr size would be like Neve input. small enuff to go in a case.

looks like an alembic preamp with diodes. try bat41. skip the 2n7000 fets. skip the assymetrical bs with one 2n4001 and one bat41. want something smooth as butter? try germanium diodes from marantz 2270 IF detector board, unbelievably wonderful.
 
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Thanks for chiming in CJ :)
It IS an Alembic preamp with diodes. (well, actually an AB763).

Would you care to add what you're saying to my schem, pretty please? :)
Sounds very interesting indeed ;)

Cheers
Sono
 
and i don't even know which is 2 and 3. look at the jack from the front, look at the jack from the back, male, female, so 4 ways to screw it up, throw in pin 1 and my brain seizes up.

you can put a lift sw on pin 1. check the reddi di schemo for more details.
 
i was sweeping up today and this print popped out from behind the book case, i believe it is the long lost alembic fb-2 one off that i did for somebody. they liked it and wanted another and i was unable to comply as the print was gone. i believe it was done on a Litton and Hurst lam, the one used on the Neve stuff. 23 K is not the best match for a 12AX7a but it is a ton better than 600 ohms. and who uses 600 ohms nowadays so if you output it into a 10K load then the plate now sees 23 x 10K = 230 K, now were talkin bass response. 48 is hard to work with, but you need a lot of turns on a core that small to get the pri ind.

i tried the alembic with a pot output, it was ok, kind of noisy and wimpy bass but when i hooked up the transformer, my socks rolled up and down with delight.

they have a new tube screamer that uses a tube but it is 450 dollars and not that impressive.
 

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i am short on bobbins otherwise i would do it. thee are a few winders floating around here, check the Magnetics forum. structure is easy, just pri-sec.
 
those will work, looks like Jensen 10K:10K

your voltage output will be high but so what, use a 100K pot, it will not drive a 600 ohm load but so what, nobody uses 600 ohms anywho. but experiment is better than words, so give it a try and see.
 

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