Recycled Rockster Reverb

[RJ Guitars]

The past several days I have been working to recycle a couple of my old amp projects into one functional unit that is to be used as part of a local organization I am involved with.

A few years back I was inspired by to build my original Rockster... which I later converted into a Rockster Reverb. It was always a great sounding amp that I added to the rotation of favorites I use whenever I get the chance to play somewhere. I had not used it near enough but now I can give it a permanent assignment and make it available to a variety of players including myself.

Before I built my first Wreck I actually hung out in the Dumble section of TAG and my first major amp build was an ODS that I built a combo cabinet for. I eventually sold that amp but kept the combo cabinet... which has been stashed under my desk for several years.

This project combines my Rockster Reverb amp into a combo cabinet and adds a few more ideas that I've been wanting to try out. It's done and sounds great and I learned a couple more things that might be of interest to you.

1) Addition of a 100pF bright cap in combination with the boost bypass cap on the 2nd gain stage.

2) Independent bright cap in the opposite position of the mini switch that switches on the boost.

3) Use of Russian 6N3C aka 6p3s power tubes. I had been using a set of black base 6L6GC tubes in this ever since I added the reverb circuit. I found a couple version fo these Russian tubes that sounded very good to me.

4) Addition of a very simple built in attenuator that I will call the rj-A10U8R... this should bring a smile to those of you who get it. This seems to bring the volume from 100% down to about 40%, while costing less than $20.00. I'm not a fan of any of the popular master volume options that folks apply to a Wreck circuit (including my own) and to my ears this seems to be better sounding solution... ll be curious if anyone has done something similar.

rj

[M Fowler]

Nice combo rj, one of these days I will get started on the one you gave me.

Trimmer on tail resistor, on reverb, on slope resistor, and others nice way to get a flexible circuit.

[RJ Guitars]

Nice combo rj, one of these days I will get started on the one you gave me.

Trimmer on tail resistor, on reverb, on slope resistor, and others nice way to get a flexible circuit.

Yeah, I had a few other options in there when i started this latest effort but I replaced those with fixed value resistors. The Rocket preamp allows a lot of freedom and doesn't seem to mind a little personal tweak. I think the mirror image build like you mentioned you have in the queue is preferable to turning the amp upside down like I did. I've found that it doesn't matter that it's not clear what each knob does, I always reach for the wrong one anyway.

This amp is really fun and hope to hear if anyone else has tried those Russian power tubes and also that simple of an attenuator. I am curious if I should expect a downside to a purely resistive attenuator - not unlike the 'Air Brake" in that respect. The speaker is still in the circuit providing the inductive load so is it fair to say that the big resistor is just turning power into heat and I won't hear it in the circuit? I know it's not that simple...

[Paultergeist]

RJ,

I may be out-of-the-loop on this, but I don't seem to have quite enough info to track along.......I am not sure if the intent is for folks to *get* the circuit just from the photos......but I am not at that level.

I was curious in particular about that attenuator? I can see the rheostat in your photo, but I cannot decipher the functional circuitry.....?

[RJ Guitars]

RJ,

I may be out-of-the-loop on this, but I don't seem to have quite enough info to track along.......I am not sure if the intent is for folks to *get* the circuit just from the photos......but I am not at that level.

I was curious in particular about that attenuator? I can see the rheostat in your photo, but I cannot decipher the functional circuitry.....?

Only a little out of the loop because the loop is getting pretty old... start with the original rockster build @ https://tubeamparchive.com/viewtopic.php?t=7300

Then maybe look into the add reverb post... https://tubeamparchive.com/viewtopic.php?t=11343

Ok, about that attenuator, it's pretty simple and inexpensive. I had a little extra faceplate space so I just added a 50 ohm, 50 watt rheostat and fed the enter tap with the speaker output. On one side of it it goes directly into the speaker and on the other side is an 8 ohm 100 watt power resistor. At the extremes in range the DC resistance is ~7.5 ohms and at 12 o:clock it's something like 15 ohms against the output transformer. It never brings the volume to zero but it knocks it down enough to enjoy some distortion without my ears bleeding. As with most attenuators, MV's, VVR's, etc, the less of it I use the better the amp sounds.

Also, I am pleased that I was able to use the lightweight speaker that was already in this cabinet. I won't recommend them above any of the well established models that most folks use for Wrecks and Rockets specifically, but it sounds pretty good. This was a project to build an amp that I thought I could leave with the CR program as a house amp and not worry too much about it being stolen or abused when the other programs that share the venue are there. With that front panel this isn't an easy amp to to fence but I am wondering if I need to get one of those 20 pound speakers to keep folks from trying to carry it off?