Who wants to proofread a schematic?

[tboy]

I've been working on a new schematic drawing of the Magnatone Starlite 431 Musical Instrument Amplifier, and the current state of my progress can be found here. It's an SVG file, which can be displayed by most modern full-featured web browsers, and re-sized as large or small as you might need without any loss in quality. The old schematic copies I've been working from can be viewed here and here, and they are unfortunately so poor in quality that I could only guess at some of the part values. I'd like to get a few more eyeballs on this other than my own, in hopes that someone else might be able to decipher the smudged/blurry/overexposed text better than I have, and of course I'd like to know about any other errors.

[The Dude]

I didn't spot anything on a "quick look over". The filament supply/filament labeling is a little funky/confusing/different to me, but it's not hard for a tech to figure out where you're going. V2 is missing and I'm not sure what the "C"s are for, but that's a petty thing.

[SoulFetish]

I see a mistake on R25. Labeled 47k, looks like it should be 1.5M

[SoulFetish]

Also, C2 & C15 look to be .047 (47n), and you have them as 4n7.

[SoulFetish]

one other thing. If you wanted to add it, they list the output transformer impedance ratio with a primary impedance of 11k to a secondary of 3.2Ω.
But those are the only errors I could find

[Dave H]

The bottom of R22 should go to the bottom of R24 not ground to bias the cathodyne.

[Helmholtz]

Are you sure about C8 (220nF)? I have a Hammond amp that uses a 50µ ecap in this place. 220nF would roll off bass content probably up to several hundred Hz.
What's the input impedance of the reverb "delay line"?

BTW, the value of R19 (47k) wired from vol pot wiper to ground looks extremely low. Maybe an error in the original schematic?
Other Magnatone circuits don't seem to have this resistor.
Removing it would at least double available volume and greatly increase bass response at max volume.

[vintagekiki]

...

Correction ...

[bbsailor]

To improve the schematic parts labeling that use analog letters but must change to a digital part value equivalent. Then, if a part value is hard to read, you could simply touch the part value to see the digital signature of that value to see its displayed source.

You could extend this concept to make each schematic component another digital named symbol to make arranging those symbols to create and label schematics, print them, and share them without degrading image quality.

This would mean first creating a schematic environment application that readers of schematics would need to see, read and share schematics.

Remember, if you can think it, you can do it!

Joseph J. Rogowski

[SoulFetish]

This can already be done if saved to a PDF, so long as the text is not converted to outlines.
i was able to find the embedded text info in this SVG file when I opened it in illustrator.

[vintagekiki]

https://www.magnatoneamps.com/schematics/magnatone_m8.pdf

[SoulFetish]

Correction ...

Kiki, i was showing him a visual of where his drawing was different than the original scan.

[vintagekiki]

Kiki, i was showing him a visual of where his drawing was different than the original scan.

SF i commented what's wrong on "drawing" (post #4).
I don't know where "drawing" was taken from (no original link), but it's most likely a drawing error.
Tube in cathode-biased (cathodyne) phase inverter, gets bias from Rk (5k6) as shown at the "original scan" and at post # 11. How it is presented on the "drawing" Rk is 105k6, which you will agree is no logic.

[SoulFetish]

SF i commented what's wrong on "drawing" (post #4).
I don't know where "drawing" was taken from (no original link), but it's most likely a drawing error.
Tube in cathode-biased (cathodyne) phase inverter, gets bias from Rk (5k6) as shown at the "original scan" and at post # 11. How it is presented on the "drawing" Rk is 105k6, which you will agree is no logic.

... hwhat?
Neverminfd.. forget I mentioned it