Master Volume in Rocket

[cworley5150]

I have searched the forum a bit, but can't find the exact answer I'm looking for. My amp knowledge is limited, but I have been experimenting with mostly Marshalls and doing some simple mods. I have awuired what appears to be a "Rockster" build running on 5881's. The amp sounds great, but I am wanting to use it in church and need a way to control the volume. My question is can a typical pre phase master volume ala JCM800 be used on this Rockster?

Thanks,
Chris

[M Fowler]

Yes I have used that type of master volume in a Rocket with EL34 power tubes. I actually wired my tone stack like a Marshall with MV.

Many like the PPIMV better but I think the other type MV works well too.

I have also used a 250kL pot on faceplate for watts control, limits the PI bias thereby lowering the amps volume but it changes the amps feel and gets dirty tones.

See the layout showing wiring of tone stack and MV which adopts to the Rocket board nicely.

See front faceplate showing location of my MV next to cut control.

See gut shot showing wiring of tone stack and MV.

This Rocket has reverb but still you can see what I have done.

[RJ Guitars]

Chris,

Take a look at this old thread - https://tubeamparchive.com/viewtopic.php?t=6603 on page 2 there is some work detailed about adding a PIG control. The Acronym was created by Zippy here on the forum and it stands for "Phase Inverter Gain" control. As it states in the thread this is right out of the Trainwreck pages. It's one of several master volume options that you can add to a rocket circuit.

This type of master volume tends to keep the amp from breaking up in the power section so it's not really something you want to use if you're trying to overdrive the power amp section. It is a very simple mod and works well for what it does.

[cworley5150]

Awesome info! This helps tremendously. Thanks!

[sliberty]

I've recently added a pre phase invertr master to a Bassman build, and really like the results. As was said it is a simple mod for sure. It allows some flexibility in that with the volume up and the master down, you generate some nice pre amp grind. And (at least in the Bassman) with the volume low and the master dimes, you get some nice power stage overdrive. And they different, so you can choose what you want.

Another option would be a VVR. I have them in both of my Rockets, and like the results. But there is a little more involved in installing as VVR as compared with a MV.

[10thTx]

I'll throw another master volume in the mix to consider.

This is what I use on my D'Mars ODS & I like it very much.

I use a delay and/or a reverb pedal in the FX. I have used a typical Marshall master volume, PPIMV, crossline mv (awful) and VVR. The FX level is my favorite and seems to color the tone the least, IMO.

I have not built this Rocket, but simply drew up a DRAFT idea for anyone who might be interested.

With respect, 10thtx

[M Fowler]

Watts control

[cworley5150]

Awesome info! This helps tremendously. Thanks!

[matt h]

(deleted)