Magnatone Vibrato any New Info?

[tictac]

Listening to Chris Isaak last night got me thinking a Magnetone preamp with vibrato & reverb would make a nice stand-alone preamp unit. Stumbled across some nice info about the vibrato circuit I had seen a year or two back as well.

It's been interesting reading about the experimentation concerning the Magnatone Vibrato circuit and trying to recreate it without using NOS parts. The papers Martin Manning and others had a share in concerning the history of the circuit and using zeners or a resistor/zener network to clone the NOS varistor were very well done. One thing I haven't been able to find though is comments about how the clone circuits actually sound so I was hoping someone could share any experiences they've had with the clone circuits....

Another alternative, The Metrosil 100-P/W/921 (a current productor varistor?) was mentioned as a replacement part for the NOS Magnatone part so this would likely be a good candidate for any new builds as well but not sure how much they cost and you need four....

Any experience or thoughts concerning this topic would be most welcome....

Thank you,

TT

[martin manning]

Sound clip comparing MOV clone and NOS varistors here: http://ampgarage.com/forum/viewtopic.ph ... 09#p326209

The Metrosil varistors would work fine (they may well be the parts used in the current production Magnatones), but I don't think anyone has a source for small quantities.

[Leo_Gnardo]

Another alternative, The Metrosil 100-P/W/921 (a current productor varistor?) was mentioned as a replacement part for the NOS Magnatone part so this would likely be a good candidate for any new builds as well but not sure how much they cost and you need four....

Any experience or thoughts concerning this topic would be most welcome....

I asked a couple years ago, and got an answer, where to buy the current varistors and how much $$, possibly from the current Magnatone builder. If you dig into the archives here you may be able to find it. Or if we're lucky some helpful TAGster will post current info.

[tictac]

So it looks like the MOV/Resistor network in Martin's post is a viable option since it closely resembles the Metrosil varistol performance.

Another builder commented on getting good results with a Littlefuse part:

LITTELFUSE V68ZA2P TVS Varistor, MOV, 40 V, 56 V, ZA Series, 135 V, Disc 7mm, Metal Oxide Varistor (MOV)

TT

[martin manning]

LITTELFUSE V68ZA2P TVS Varistor, MOV, 40 V, 56 V, ZA Series, 135 V, Disc 7mm, Metal Oxide Varistor (MOV)

That is the same type of ZnO MOV I used in the network I devised to imitate a SiC varistor characteristic. If you replace a SiC varistor with that part you will get a choppy tremolo effect.

[tictac]

Thanks for that info....

I thought I checked the drawing you posted and the number was different.

The drawing "I thought" I got from your post was three V82ZA05P MOV's in series with a 750k, 100k, 75k resistors and those networks in parallel....

So is the V68ZA2P actual pn or do both parts simply have the same rating?

Is the drawing I just described the correct one to mimic the NOS performance?

TT

[martin manning]

There are three different MOV's in the substitute. Each MOV and R combination creates a voltage break point and an I-V slope.

[tictac]

Oh Duh!

Yes that's the drawing I have, just need to be more observant & not post late at night....

Thanks again....

TT

[Zack Engineering]

If this is NOT appropriate let me know, just trying to help the DIY groups.

I have Magnatone NOS Workman Varistors For Sale !!
Genuine Silicon-Carbide, 1/2-Watt Disc with Radial Leads and 1-Watt with Axial Leads
Both have been tested in Magnatone amps and meet or exceed the specifications for DIY Magnatone Pitch-Shifting circuits

Search EBAY or AMAZON.COM for: Varistors NOS
Thanks, Zack Engineering
503-757-6654

[trobbins]

Did you match them into pairs at least for that price?