I am back in the US from the trip to Europe. Good old Europe.
Anyway, I did some experiments with edcor 600:15k stepup trafo, and it works great and sounds amazing.
Basically i have normal volume pot on the input, followed by the buffer, whatever you fancy, feeding the transformer. You can have 0 gain, that is 1x, or two levels of step up, 3x or 6x. I decided not to use switch, just the wires to cinch connector. One will simply plug it based on the gain needed.
I ordered some more trafos...since this is likely going to be the best pre.
Anyway, I did some experiments with edcor 600:15k stepup trafo, and it works great and sounds amazing.
Basically i have normal volume pot on the input, followed by the buffer, whatever you fancy, feeding the transformer. You can have 0 gain, that is 1x, or two levels of step up, 3x or 6x. I decided not to use switch, just the wires to cinch connector. One will simply plug it based on the gain needed.
I ordered some more trafos...since this is likely going to be the best pre.
While browsing edcor page, i noticed this line level transformer. Anybody used it?
Could offer lot more steps...
https://edcorusa.com/products/xs4400-quadfiler-1-1-1-1-matching-transformer
Could offer lot more steps...
https://edcorusa.com/products/xs4400-quadfiler-1-1-1-1-matching-transformer
Made some more experiments. Surprisingly, stepup edcor does not work well with aikido tube buffer. Not sure what is the reason. Aikido itself as buffer measures well and sounds clean. But aikido feeding edcors has terrible rollof on low frequencies. No bass. Must be some incompatibility.
On the other hand, any solid state buffer i tried, b1, complementary jfets, opamps, all worked very well with edcor. I ended up pretty much with front end of VFET or M2, so no surprise it sounds great.
Still surprised by aikido...
On the other hand, any solid state buffer i tried, b1, complementary jfets, opamps, all worked very well with edcor. I ended up pretty much with front end of VFET or M2, so no surprise it sounds great.
Still surprised by aikido...
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Here is how i connect those edcor transformers.
For those who like some pleasing distortion, use 600:15k edcor as in M2.
For those who like clean step up line transformer, i highly recommend xs4400. It can handle much higher peaks without limiting.
I made three preamp and they surpassed all other preamps i tried (including nutube korg b1, acp+, whammy, scg, ba3fe, goldmund, Wayne's pre, schiit, and bunch of tube pre).
The better the buffer, the better result.
For those who like some pleasing distortion, use 600:15k edcor as in M2.
For those who like clean step up line transformer, i highly recommend xs4400. It can handle much higher peaks without limiting.
I made three preamp and they surpassed all other preamps i tried (including nutube korg b1, acp+, whammy, scg, ba3fe, goldmund, Wayne's pre, schiit, and bunch of tube pre).
The better the buffer, the better result.
Attachments
Totally interested! But please start another thread so as to not threadjack.
Will do...
This threat got derailed few times. First, i wanted to use tvc as volume control, but as you know, those high quality transformers with many taps and selector are not cheap.
I realized i can use normal pot, buffer and step up trafo to do that job, plus infinitely more steps.
Second, i assumed tube buffer will work well, but it was a disaster.
So i am pretty much where ZM, iron pre. Well, it works!
Now to test lot more step up trafos...
Cheers!
This threat got derailed few times. First, i wanted to use tvc as volume control, but as you know, those high quality transformers with many taps and selector are not cheap.
I realized i can use normal pot, buffer and step up trafo to do that job, plus infinitely more steps.
Second, i assumed tube buffer will work well, but it was a disaster.
So i am pretty much where ZM, iron pre. Well, it works!
Now to test lot more step up trafos...
Cheers!
Let's derail it some more 
Here's what can be a finished, compact solution
https://www.diyaudio.com/community/threads/transformer-volume-control-tvc-by-dvb.402116/
Here's what can be a finished, compact solution
https://www.diyaudio.com/community/threads/transformer-volume-control-tvc-by-dvb.402116/
hello, can you say number corresponding to "very small source impedance". Because I have one and not very happy with my tube dac. Can you drive TVC with transformer on previous stage with say 300 ohm output impedance or this is not low enough?
If I remember correctly, the CCS output was below 500R (at 1kHz).
If the output (tube) stage capacitor coupled, proper planning requires (series C - very large L).
If the LF bump (there is always one in these cases) near to estimated lower bandwidth, the "tone" may muffled, smeared in the lower registers.
The transformer drived TVC generates another problems.
Without proper (frequency and SQ behaviour) measuring (or even simulation) there is no telling if it will be good.
If the output (tube) stage capacitor coupled, proper planning requires (series C - very large L).
If the LF bump (there is always one in these cases) near to estimated lower bandwidth, the "tone" may muffled, smeared in the lower registers.
The transformer drived TVC generates another problems.
Without proper (frequency and SQ behaviour) measuring (or even simulation) there is no telling if it will be good.
Not that any of you care, but i will post some data about those two edcor line level transformers above mentioned. Kind off comparison.
Then i post two other line level transformers, these time balancing mic transformers. Some interesting findings.
Then perhaps some data about ground break line level transormers. So lets do it.
Then i post two other line level transformers, these time balancing mic transformers. Some interesting findings.
Then perhaps some data about ground break line level transormers. So lets do it.
Ok, now for the surprise. We have here small mic balancing transformer from radio shack. I used these long time ago when i was soundman for our company music group. Great time.
Anyway, these are absolutely tiny in comparison to big edcor line level transformer. I used these as mc cartridge step up.
They are i believe 600:10k ohm, but i am not certain.
Here picture how they look in original steel casing and taken out for measurements.
Anyway, these are absolutely tiny in comparison to big edcor line level transformer. I used these as mc cartridge step up.
They are i believe 600:10k ohm, but i am not certain.
Here picture how they look in original steel casing and taken out for measurements.
