Highest gain amps that use 2.7K .68uf, how to add sizzle?

[Nickerz]

On my journey I've come to realize that I absolutely adore this combo and consider it crucial to the Marshall feel and tone. The Soldano values feel too bloated (though this is somewhat eleviated with a boost pedal) and the Fender values tend to give a more Orange or Mark feel depending on negative feedback and preamp circuit. The VH4 seems to play in this ballpark, but I wonder what else is out there that isn't explicitly a hotrod JCM (even if it is spiritually derived, e.g. the VH4).

I've been playing with the Jose circuit and once I change these values I start to dislike the amp, because it starts to feel more 5150\SLO in nature.

But one thing I'm missing from the modern amps is the SIZZLE. Now one circuit that comes to mind that did this, that is really old is the ADA MP1.

https://www.youtube.com/watch?v=4OlJzwg ... sseLammert

I wonder what part of that circuit does, and if since then we've come up with some JCM800 circuits that have pushed things forward. e.g. I know the Fortin designs are still Jose at heart, and I wonder what part of these designs are truly "modern."

[thetragichero]

if this is a four hole input kinda amp (i much prefer these even on the higher gain jcm800-type) you can do the ~68 plexi thing and change the 22nf coupling cap on that stage to 2.2nf

[R.G.]

Sorry, I don't have the schematics of all amps memorized. Where exactly in the circuit do the two components live? Cathode of first stage? Got a link to a reference schematic?

And what exactly is "sizzle"? I'm guessing it's a rise in high frequency gain, but at what frequencies and how much?

[roberto]

And what exactly is "sizzle"?

A typo maybe? Was it SIZE related to previous thread on girth?

[Nickerz]

Sorry, I don't have the schematics of all amps memorized. Where exactly in the circuit do the two components live? Cathode of first stage? Got a link to a reference schematic?

And what exactly is "sizzle"? I'm guessing it's a rise in high frequency gain, but at what frequencies and how much?

IDK it's hard to convey.

https://www.youtube.com/watch?v=FI4y79m ... sseLammert

This clip demonstrates it the best. Just that very upper mid sound. If I had to guess... 3k?

[blackeye]

If you are talking about the cathode resistor/capacitor on the the first gain stage, I doubt a change of 300 ohms will affect the flavor of the amp that much. The first stage is not overdriven by guitar level signals and probably has less than 2% harmonic distortion. I wonder if the tone you seek is elsewhere in the circuit.

[R.G.]

IDK it's hard to convey.

https://www.youtube.com/watch?v=FI4y79m ... sseLammert

This clip demonstrates it the best. Just that very upper mid sound. If I had to guess... 3k?

Most historical audio jargon (which isn't very explicit, either) attributes boosts around 2kHz as "presence". Most guitar amps with presence controls use feedback from the OT output to a long tailed pair phase inverter to give the "presence" a boost. Maybe some amps kick this feedback boost up a bit higher. Maybe.

As you say, if it's hard to convey, it's hard to attribute it to anything in particular in the amp.

[brewdude]

I’m not really a fan of the tones you seek, but…
Different speaker? Maybe, Celestian Vintage 30?
Bright cap?

[Nickerz]

I’m not really a fan of the tones you seek, but…
Different speaker? Maybe, Celestian Vintage 30?
Bright cap?

From a practical perspective, you're not wrong. However in this video they are using the same cabinet. So it's something in either the preamp or poweramp. What might be notable in another part of this discussion is both the Framus Cobra and the ADA1 clip, I think they're both using different NFB values (by virtue of using the Mesa poweramp). So it might be worth exploring if part of for instance Mike Fortin's designs, he's changing NFB values. If so, then I think I understand what "modern voicing" is in that regard.

[Mattallica]

Something to try would be adding or reducing size of treble peaker caps, or reducing size of plate resistor caps.