Liverpool/Rocket Control Idea

[Subjecttochange]

I am thinking about implementing an even simpler version of the liverpool or rocket preamp into an existing amp. The thing is... because I have limited space (and wonderfully made faceplate)- I can only fit a volume and tone control. What do you think would be the best way to abbreviate the tone stack? I don't want to loose the ability to control it- but I am ok compromising some versatility- since this amp has a "cleanish" channel as well.

[M Fowler]

Your going to be limited to P-P pots, dual pots or adding switches to the faceplate.

[Structo]

Or drill the back panel and mount the extra pots there.

Or is this a combo?

[Colossal]

Or use trimmer pots in the right values and mount them on the tone stack on the board and then just use an external volume knob. You could devise your own tone control, cut control, or even use the other hole for a VVR. Using trimmers on the board would allow you to retain the Trainwreck tone stack but would require some playing to find a setting that makes you happy before mounting the chassis in your head cab.

Good luck with your build!

[Subjecttochange]

Thanks guys.

Yeah it is a combo cab... boo. I was thinking of mounting trim-pots on a board (got the idea from the HRM). I was thinking of trying to set everything then add a cut control.

I'll try to draw something up tonight or tomorrow. Would you guys be willing to look it over?

[rooster]

Yeah, I think that's a pretty cool idea in so many ways. And if you think about it, you are making what would look like the VOX built Brian May Special - two knobs, Volume and Cut. But yours would use the Brilliant channel, of course.

On the downside, because the BM amp is still the same size as a typical AC30, it looks like the buyer got ripped off. Like a Cadillac with a single bucket seat, a speedometer, and a steering wheel.

...But getting over the limited looks, it could get the job done.

[Subjecttochange]

Yeah it does seem like you're getting cheated a bit. I'm building the amp for a good friend and he is all about the fender sound- though he wanted the option for some voxy crunch. So I concentrated a lot on his fendery clean preamp. I decided to go with a typical Ef86 voxy channel (hence the two knobs)- but still haven't gotten into it (paired with the power amp I've got in there). No matter what values I try- it's just not doing it for me. Since he cares little about the circuit/tube type- and only about the sound... I am gutting the vox preamp.

I've always liked wrecks- because they're so dynamic. Though for this sound- it seems like getting a bit extra drive out of the rocket circuit is better than toning down the Liverpool. I think that I may actually keep my 6-way switchable coupling capacitor control from the Ef86 channel- then add a cut control on the rear of the amp. Might just work- little extra flexibility.

Still haven't done that drawing. I may try putting resistors in to model the pots being at noon in the tone stack. May be a good starting point.

[Subjecttochange]

Alright. Here's a little recap. Two front controls- one for volume one for tone. Can it be done? Yes... should it be done... eh

What I did is I basically used the rocket preamp as a base. THen did the following modifications.
-Replaced C2 with a 6 way rotary selector (from orig EF86 channel)
-Reduced R5 to 1.2k and bypassed it with a 10uF
-Used resistors in the tone stack to act as the log pots would between 12 o'clock and 1.

I've never heard a rocket before- but this sounds great. It's got the perfect amount of drive and the tone is pretty neutral allowing the coupling cap to do the tonal dirty work (which will probably just be used for switching between HB/SC/P-90s/etc I am guessing). Much more dynamic and expressive than the channel I had before and more than the cleaner fender channel that's in there next to it. Unfortunately... that's going to need some work now... The rocket pre sounds too good next to it.

I'll def. be using this design in the future whether or not space is an issue. Though- having the treb/bass pots would be nice- this is a great sounding little guy.

[M Fowler]

The Brian May AC30 has one knob the Volume control.

[Subjecttochange]

Sort of funny looking...

However, that's basically that's how it is. I took the well timed info from another recent post about where everyone sets up their Rockets... then adjusted the tone stack resistors to fit somewhere within those values. Worked better than I had anticipated. Maybe a bit too much bass- but that's pretty easy to fix. Swap out two resistors and I am good to go.

Most likely though... it sounds more like the rockster 66 that some guys around here have built, than it does a "true" rocket. Those 6L6s are screwing it all up for everyone.

Anyone have a link to or know of a killer fender-ish preamp? The thing has basically got a tweed Bassman power section- so anything American will feel right at home. The rocket pre is so much better than clean channel... more dynamic and lively even when they're both running clean.

Lastly. The amp has never felt loud. I modeled it after (just like everyone does a one point) a bassman- then changed things here and there. The thing is... it's never seemed horribly loud. I can't even crank my 18W or TW Express clone past 11 o'clock in my living room for fear of permanent hearing loss- but this thing can be cranked all the way up. Though it is loud- it's not THAT loud. Is there something wrong or is that how bassmans are?

I realized that I may want to move this discussion to "Technical Discussion"... anyone willing to follow me would be super helpful! I'll post the link.
Thanks

[Subjecttochange]

https://tubeamparchive.com/viewtopic.php?t=10683