Varistor Characteristics for Magnatone Vibrato Circuits

[JazzGuitarGimp]

I'm thinking 100-200pF. Larger ones will likely remove too much HF and dull or darken the tone, but it might be interesting to find out. Another way would be to put the pairs of Zeners back-to-back, and then put a cap across each pair. That would be adding only two more parts.

Something tells me that having a resistor in series with the cap makes sense. I'm thinking your last suggestion might get you there.

[Smokebreak]

I had a similar experience with ubxf, with the varistor substitutes. They worked, but there was an accompanying clicking sound. The sound didn't increase with the volume, but was always there.

ubxf, was your clicking sound similar to the one below?

At first there was a clicking and chirping sound, and a 12au7 swap fixed the chirping, as did caps across the 1Ms with the original au7 that had the chirping. I started at 150p for the caps and went up to 1150p, but couldn't get rid of the clicks, and some HF was indeed affected as cap value increased.

Martin's working on a new device so I'll test that out soon.

Also of note is that to my ear, the "core tone" of the amp was the same with the NOS and the zener sub, with the vibrato "off". The high resistance of the NOS varistors with no voltage across was the variable here, I believe.

Right in the middle of soldering and recording all the different varistors, my neighbor started banging on the ceiling, which killed the consistency in recording. The recording with the NOS had the amp opened up a lot more(commence banging on ceiling), and the recording with Martin's device was with the amp at anemic levels, so that accounts for the difference is core tone and levels, but again, this is mainly for the purpose of comparing the effect, so it should suite just fine for these efforts.

Zeners : https://soundcloud.com/jeremyslemenda/var-sub-150p
NOS: https://soundcloud.com/jeremyslemenda/1a

[ubxf]

Thanks for the sound clip, yes it's exactly what i had here. No chirping but the same clicking. I didn't get a chance to experiment with the capacitors yet but i will probably later today

[M Fowler]

The NOS sound like a warble effect and the Zener vibrato.

[gktamps]

Smokebreak - I've seen the Russian NOS in various voltages. Which did you buy, and have you received them yet?

Cheers,

Greg

[Smokebreak]

Smokebreak - I've seen the Russian NOS in various voltages. Which did you buy, and have you received them yet?

Cheers,

Greg

Hey Greg, the ones I got are 100V and they're still on their journey from Russia. They are the ones suggested on the Mag/Valco group as being a viable substitute. Biased FETs were also suggested. I'll post the results when I get em. I'll dig up the link too.

here it is : http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... 081551454"

[Reeltarded]

With any luck Oliver Archut is drawn into the forum with additional information he has about the varistors and his huge background of all things electronic.

Oliver has the plans for Siemans EL34s..

[Smokebreak]

Sorry for the delay guys. I got a cab for my amp today, so I drug it out and tested the cheapo russian varistors.
These are the 100V, quick and dirty recording. I was turning knobs the whole time .
They are definitely FM with little side effect. There is a thump on lower frequencies that isn't quite audible in the recording, but it's there, and should be tweakable.
Also, it sounds like mids are doing the most warbling.Lows get a thump, and highs are less affected. Not to shabby for $1.
https://soundcloud.com/jeremyslemenda/s ... -evening-3

[Reeltarded]

WHAT!???!!! Give. Me. That.

You can bandpass this whole shooting match. Lopped off is groovy. I'm in love with it. Hrmmm..

A Rocket with that in stereo with a plate reverb. I'm gonna poop myself.

[Smokebreak]

They are grey in color. I'm still trying to find the 100v link, though others may suit, and are visible. I bought a small bag. Let me know if you'd like me to drop a couple in the mail.

[Reeltarded]

What is the amp you have this in?

[Smokebreak]

Maggie 213. Fantastic amp, vibrato aside . cascaded .
https://tubeamparchive.com/viewtopic.ph ... =magnatone

[Reeltarded]

That is a cheerful noise.

[martin manning]

These came from Ukraine, right? things are kind of crazy there now.

[Smokebreak]

Exactly. I think that's why they're only selling 56, 150, 220V. They're on to us. Shipping is still somewhat reasonable though.

http://www.ebay.com/itm/Vintage-Russian ... 2c633b4b21[/url]