NOS John Mayer Sig / Wonderland 100W

[jfs322]

I think you are right, this is probably V2
There is also a signature on the back, so I assume this is JM signature. My wrong

Nope, it is a different "JM" -- Joe Mloganoski, co-founder of Two-Rock. The top signature is Bill Krinard's (the other co-founder of Two-Rock).

[neskor]

Thanks for the info
Sound was great, but both #124 and mine #102 was IMHO better sounding.

[rootz]

My bad, you are totally right. MK3 has the tweed style mixer, 2 the Fender style. My apologies for the confusion.

[rootz]

Just curious: what ODS type is the preamp? 102?

It will never sound like a ODS though. Contour, reverb, half a dumbleator, etc. Lots of differences.

[jfs322]

Just curious: what ODS type is the preamp? 102?

It will never sound like a ODS though. Contour, reverb, half a dumbleator, etc. Lots of differences.

From what I recall of the Custom Reverb Signature line, they are all high plate skylines. The Classic Reverb / Mayer line of amps are low plate classics.

[dbharris]

Still cool to see more gut shots. Thanks for sharing! If nothing else this was around the same time period as the JM sig amps and we see similar parts selection...draloric LCA for most of the circuit, NTE GNFB resistor, philips bypass caps, new production dale plates, etc. Very cool!

-Dan

[norburybrook]

Diodes: https://ixapps.ixys.com/DataSheet/DSEI12-12A.pdf

are they diodes? they look like voltage regulators at first glance. I've never seen a diode like this


you learn something everyday.


M

[pompeiisneaks]

Yes I've seen both single and dual diodes like this a ton in SMPS's and the like, the larger body allows for better current handling I think, and heatsinking if needed.

~Phil

[neskor]

I just removed cap from RETURN pot and sound is now so much clearer
What is the purpose of that cap anyway?

[jfs322]

I just removed cap from RETURN pot and sound is now so much clearer
What is the purpose of that cap anyway?

It adds a little brightness to the reverb signal, and at higher reverb levels, adds some "splash." If you prefer it without it, then keep it without a cap. In fact, it's something that Two-Rock apparently preferred as well, because on the Crystal amps (a re-release of the JM circuit about 8 years after the limited edition run), they removed that cap.

[martin manning]

I just removed cap from RETURN pot and sound is now so much clearer
What is the purpose of that cap anyway?

It adds a little brightness to the reverb signal, and at higher reverb levels, adds some "splash." If you prefer it without it, then keep it without a cap. In fact, it's something that Two-Rock apparently preferred as well, because on the Crystal amps (a re-release of the JM circuit about 8 years after the limited edition run), they removed that cap.

I think just the opposite. Any time you have a cap to ground it is going to bleed off high frequencies. This 10n cap across the return pot will reduce high frequencies and reduce the level of the reverb return signal.

[neskor]

I had a same feeling, more pF darken the sound, also lower the reverb level

[jfs322]

I just removed cap from RETURN pot and sound is now so much clearer
What is the purpose of that cap anyway?

It adds a little brightness to the reverb signal, and at higher reverb levels, adds some "splash." If you prefer it without it, then keep it without a cap. In fact, it's something that Two-Rock apparently preferred as well, because on the Crystal amps (a re-release of the JM circuit about 8 years after the limited edition run), they removed that cap.

I think just the opposite. Any time you have a cap to ground it is going to bleed off high frequencies. This 10n cap across the return pot will reduce high frequencies and reduce the level of the reverb return signal.

Yes, my mistake -- I was speaking in terms of what removing the reverb cap would do (i.e. brighten up the reverb a bit relative to the sound with the cap in place), not speaking in terms of what adding the cap does. So I was just talking about it from the "flipside of the coin," so to speak. My apologies for the confusion.

[Bombacaototal]

I think Two Rock added the cap to (i) address the reverb hum, which happens due to the classic tone PT and small headshell, and placement of the tank. (II) reduce the amount of reverb for a better dry/wet ratio given they use the 1M resistor on the dry path which really reduces gain (III) as mentioned above to make the reverb darker

[martin manning]

I think Two Rock added the cap to (i) address the reverb hum, which happens due to the classic tone PT and small headshell, and placement of the tank.

The value of the cap used will have very little effect at 50-60 Hz, so reducing hum is not likely to be a factor. I can agree that a poorly positioned reverb tank can create a hum problem, but why do you think the Classic Tone PT is worse than others?