From Mono to Pseudo Stereo - does it exist a Tube circuit that do that ?

[kagliostro]

Some years ago I assembled a Solid State (IC based) Theremin Kit

that Kit had a "Stereo" output, the mono signal was processed using a TDA 3810 IC that gives a Pseudo Stereo output

I would like to know if there is a Tube circuit that can obtain the same result and, if it exist I'm interested to a schematic

Thanks

Franco

p.s.: Note that I've no idea to which is the process applied to the signal to enter Mono end exit Pseudo Stereo

[shooter]

the "basics" would be,  stereo jack signal in(L R signal), mix R's at input jack to "mono", amplify, then split signal for "left", "right", speaker.
each speaker will output a "stereo" signal (L R mixed).

 

[acheld]

Note that I've no idea to which is the process applied to the signal to enter Mono end exit Pseudo Stereo

I was reading this the other day, it gives some ideas about how pseudo stereo is implemented:  https://www.soundbridge.io/pseudo-stereo-effect

My current rig uses two amps, with a signal splitter --> amp one is dry signal only, amp two gets the pedals.

I would love to use the stereo effects in some of my pedals, but honestly it is a pain to do with more than one pedal in the chain. 

[PRR]

> mono signal was processed using a TDA 3810 IC that gives a Pseudo Stereo

If you can possibly find that kit, or any similar fake-stereo kit, or do it with opamp chips, don't fool with tubes. The impedances and gains are semi-critical and a good inverter in tubes is two triodes at least. Find your "tube flavor" somewhere else in the system.

Start with the TDA3810: https://pdf1.alldatasheet.com/datasheet-pdf/download/19305/PHILIPS/TDA3810.html

Work out the internal and external circuits. The signal goes through and back again. There's a mix/difference network and a twin-Tee filter, all switchable and criss-cross. It might makes sense if re-drawn one mode at a time.

[PRR]

The Signetics datasheet with filter curves:
www.elektronikjk.com/elementy_czynne/IC/TDA3810-2.pdf

Apparent error in most schematics:
http://www.geocities.ws/podernixie/audio/tda3810-en.html
"pins 3 and 5 must be swapped."
Simplified project:
https://www.aaroncake.net/circuits/stereosynth.asp?showcomments=all
archived: https://web.archive.org/web/20130522015802/https://www.aaroncake.net/circuits/stereosynth.asp

"FULL" 1987 Signetics chip datasheets, >1000 pages
http://www.bitsavers.org/components/signetics/_dataBooks/1988_Signetics_Linear_Data_Manual_Vol_1_Communications.pdf

I think TDA3810-pins-3-5-fix.gif has the right connection at pins 3 and 5?

[PRR]

Article with theory
https://schematicsforfree.com/files/Audio/Circuits/Compressors,%20Limiters,%20Loudness%20&%20Gain%20Control/Compressors%20%26%20Limiters/Audio%20Expander.pdf

[kagliostro]

Many Thanks to ALL

@ PRR

Thanks for the link, I'll read with interest, the theory about is unknown to me

Franco

[Bash]

Using a mono amp with two completely different speakers might do the trick.

Or add a bucket brigade circuit that slightly delays one of the signals.

[kagliostro]

Ciao Bash

My question is related to something I didn't specified

The input, as understandable, will be a single mono signal from a guitar buth then it will be followed by a stereo amp

Franco

[Bash]

In that case I'd just add a mono-out/stereo-in fx loop.

[kagliostro]

.... mono-out/stereo-in ....

       


Franco

[Greenwichpaul]

as far as I know (i hope someone will correct me if I'm wrong) the 3810 uses simple comb filtering; so some frequencies are emphasised in one channel, and the other channel does the converse.

I think if I were doing it, I'd use the Fender harmonic trem design, and send the two outputs to each side of the stereo amp.. You won't get a straightforward trem if the speakers are distant from each other; ie the phase cancellation will be less, but it will add harmonic and phase complexity to the resulting sound field, with the trem set on a slow speed.

Alternatively, something like the magnatone stereo vibrato, on a low setting, would give a more complex stereo sound.

Hope I've understood the question, forgive me if not.

[PRR]

...i hope someone will correct me if I'm wrong...

I read the links linked above, and if that is a comb, it is a one-tooth comb.