I don't have the specific book at hand, and am too tired to go up the attic for my Ruben Lee. Here's Flanagan Handbook of Transformer Applications 1983. If you think he is wrong, please write the book.
"Satisfactory wideband performance is a compromise. Any superior feature is paid for by a loss of another feature."
I love the picture of the 1948 analogue to digital converter: a special cathode ray tube, see pages 33 to 35 of https://archive.org/details/bstj27-1-1/page/n33/mode/2up
CCS loaded #26 preamp, S&B TX102 TVC, 2V RMS output (measured a decade ago).
Nice #26 peamp measurements. I see you used a TVC.
Was the TVC on the output?
MarcelvdG's post led me to the public form.
Yes, this is 4-bit. I know I saw "more" in an internal memo but perhaps not even from BTL.
As I wrote, it's Stevens & Billington (S&B) TX-102 (copper, if I remember correctly Mk2).
Most solutions seem to either use matched LDRs (a pain to match) or use processor control, which then often is used for relay input control as well as both kinda go together.
So the attenuator arrived 3 days ago but I've just been too lazy to rig up my last 7805 to run it...
PSA: If you design anything, and it doesn't use more than 100W of power, use 12 volts (AKA in this example, put a 7805 on the board)!!!
PSA: If you design anything, and it doesn't use more than 100W of power, use 12 volts (AKA in this example, put a 7805 on the board)!!!
I used a PEC 100k linear potentiometer with parallel law faking resistor (10k if I remember correctly). It worked well, but after 1 or 2 years it began to give scratching noise when turned up or down. It turned out the reason was some DC flowing through it, due to the output capacitor polarization. Now I use a 24-step rotary switch, works for me.
I'm interested in your thoughts on this module. They're selling it on Audiophonics as well, but I couldn't find any reviews apart from the short one on there.
Seems like it should be 1024 steps, but that's crazy, right?
I haven't used it as a volume yet, but I fired it up, and it does have over 1000 steps. It takes more than one minute to go from the lowest setting to full blast and it seems to work as expected.
Translation by Google: "I have George Stantscheff designs from Australia. Joints and light-sensitive receiving teeth (Optocoupler) this variable on both L and R channel."
Remember, all posts much be in English or have a translation included 🙂
Ok. I decided to shoehorn it into my existing pre, screw building yet another pre!
Anyway, the results are mixed but good.
The good: The input impedance is 50k throughout the volume control range. The bad: The output is 1024 steps but it's linear, not log. That's fine for most people, but the lowest setting might be too loud for some.
Also good; The remote works extremely well - no need for line of sight, the remote makes the room flash in IR but bad is there is only fine control, no course.
Good: There is a mute function on the knob and remote, there is a "back to earth" setting on the remote that beings the volume down almost all the way meaning if you had the volume up way too loud on something quiet, and something loud comes on, you can only mute from the knob. You need to use the remote to return to earth or stop the playback while you turn the volume down for several seconds.
Overall, I'm happy with it for the money, for sure.
Anyway, the results are mixed but good.
The good: The input impedance is 50k throughout the volume control range. The bad: The output is 1024 steps but it's linear, not log. That's fine for most people, but the lowest setting might be too loud for some.
Also good; The remote works extremely well - no need for line of sight, the remote makes the room flash in IR but bad is there is only fine control, no course.
Good: There is a mute function on the knob and remote, there is a "back to earth" setting on the remote that beings the volume down almost all the way meaning if you had the volume up way too loud on something quiet, and something loud comes on, you can only mute from the knob. You need to use the remote to return to earth or stop the playback while you turn the volume down for several seconds.
Overall, I'm happy with it for the money, for sure.