Adding mid control to Rocket?

[steeve_a]

An alternative use for the Midrange hole would be a multi-position switch that switches different treble-pass caps in.

Now THAT'S a creative, cool idea. Thanks....I just might do that...

One thing good about that idea is that switching the treble caps does have a very big effect on the midrange response, so that it really is Midrange control.

Unfortunately not an option on the Crate V-18 since I am using the factory boards- I'd need a rotary selector switch with a diameter of 16mm or less..

BTW if you have a spare pole or two on your rotary switch you can also change the slope resistor as you change the treble cap. Or just do that for a few of the positions.

[dehughes]

Very cool ideas...

What values of treble-pass caps would you all recommend in an AC30/Rocket circuit?

[dave g]

I would stick to values between 50pF and 500pF. 500pF will give you something that looks practically like a Marshall tonestack, and the smaller you go the more midrange you cut.

On my Rocket I actually put a DPDT switch on the front panel that switches the treble cap in the tonestack from 50pF to 500pF while simultaneously going from a 500pF to a 1nF for the first coupling cap. It's like a Vox/Marshall voicing switch; more chime on the cleans when on the Vox setting, but thicker and meaner distortion when on the Marshall setting.

[steeve_a]

I would stick to values between 50pF and 500pF. 500pF will give you something that looks practically like a Marshall tonestack, and the smaller you go the more midrange you cut.

On my Rocket I actually put a DPDT switch on the front panel that switches the treble cap in the tonestack from 50pF to 500pF while simultaneously going from a 500pF to a 1nF for the first coupling cap. It's like a Vox/Marshall voicing switch; more chime on the cleans when on the Vox setting, but thicker and meaner distortion when on the Marshall setting.

Great ideas! I do think that if you were using a 6 position rotary switch you could add in some values that weren't strictly old school Vox or Marshall- like 750pF or 1000pF (which I would call mid boosts in a Fender BF/SF style amp). But for a DPDT switch, I agree with you completely on using 50pF and 500pF.

So can you toggle the DPDT switch when the amp is on, or do you have to put it in standby or turn it off first? Perhaps you can spell out the details of the switching circuit...

Thanks!

Steve

P.S. UPS is supposed to be delivering the Crate V18 tomorrow- I'm sure that I will wire in the switch you suggest because I was a bit concerned that the sound might be more chime than chunk. I already rewired up one V18 as a killer clean machine so I want this one to be able to get down and dirty... I understand that Ken's power supply is one big difference between the Rocket and the AC30, but I will not be touching the switching power supply board on the Crate, although I may want to change the B+ dropping resistors on the audio board to better emulate the Rocket voltages...

Many thanks to everyone here for their great suggestions!

[dehughes]

Ah, the treble cap in the tonestack...I was thinking of a treble bypass cap for the volume pot...using different values for that. Is that a reasonable idea? Would the same 50pf to 500pf values apply for this as well? I only ask as I like the AC30/Rocket tonestack as is...

[Fischerman]

Look for Paul Ruby's (IIRC) build that he mentioned in this forum. In one he added a switch that changed the tonestack AND first coupler (again...IIRC) from the stock Rocket/AC30 values to the early Mark Abbott schemo values. I think his assessment was...for low to medium volume Voxyness...use the stock config...for cranking and wailing...use the 'mid boosted' config.

[jaysg]

An alternative use for the Midrange hole would be a multi-position switch that switches different treble-pass caps in.

Now THAT'S a creative, cool idea. Thanks....I just might do that...

I can't take credit for that. Paul Rivera was doing that in the late 70's. The Jay Graydon solo on Peg was a silverface DR with that mod, among others.

[Fischerman]

That's essentially what the Mid Boost in a Dumble is. It's just a 330pF Treble cap in series with a .002u cap and the switch bypasses the 330pF cap for the boost.

[Zippy]

An alternative use for the Midrange hole would be a multi-position switch that switches different treble-pass caps in.

Now THAT'S a creative, cool idea. Thanks....I just might do that...

I can't take credit for that. Paul Rivera was doing that in the late 70's. The Jay Graydon solo on Peg was a silverface DR with that mod, among others.

Does that predate the Matchless configuration as shown in this schematic?

https://tubeamparchive.com/download/file.php?id=6389

[Fischerman]

Zippy,
There is a thread in the Dumble section about the SSS. Some of those early clean monsters he built had Hi and Lo filters that were multi-position switches with different caps. IIRC, Cristopher Cross' Dumbleland 300SL that SRV used to record Texas Flood had those in it.

I can't remember where I first saw that cap-switching in an EF86/AC15 type of thing...maybe it was Matchless. IIRC, the Lee Jackson Metaltronix had something like that too.

And there is something like that in one of my wahs...ya know...so I can have 5 totally unuseable sounds in addition to the one shitty one.

[Zippy]

I've worked on some of the Ampegs that had those various switchable filters - like you say regarding your wah, it is nice until you figure out what you want, after that they are just baggage.

I did a similar thing with my ES-335 about 30 years ago - installed a panel over the lower f-hole with mini-toggles for coil splitting, phase reversal, etc., ad nauseum... Turns out that it worked best with most of them in the off position. If I didn't need the sounds of the ES-335, I needed my Strat. Duh. Interesting to learn many years later that both Elvin Bishop and B.B. King ignore the Varitone switches in their guitars as well.

Anyhow, I'm interested to learn which switch settings that DC-30 users find most useful (with which guitars and in what applications).