36watt "lite"

[floridajack]

been using my recently built 36wtter for a month now and realized that i'm always plugging into the tmb channel. (that sound is why we LOVE these amps!!)

anyone interested in a 36watt "lite?" i'm thinking - add a mv control, a nfb, and a 18/36 watt switch in some of the standard faceplate holes (and having a custom faceplate cut to cover any leftovers.) itching to start another build

comments??

floridajack

[rjgtr]

There are a few who have done a sort of 2203 preamp into an 18 watt output. For a TMB you need at least 1 1/2 12ax7's so a Lite TMB isn't really as practical. You don't really save a lot.

However, you could make a one channel 36 watt using a "normal' Marshall style layout or chassis. This would give you two channels (lead and bass?) feeding the TMB tonestack and possibility of a presence control.

[zaphod_phil]

To follow the usual naming conventions, a 36W Lite would only have a Normal channel. In your case, you're only getting rid of the Normal channel, which is half of a 12AX7's worth. There's three things I can think of that would be worth doing, taking up from rjgtr's suggestions:

1 - One of Richie's 36W TMBs keeps the Normal channel and just feeds it into the TMB side - http://www.mhuss.com/18watt/schematics/36wTMB5.pdf
You could try and build that one.
2 - Build a 1987 Plexi style preamp with Lead and Bass channels you can jump together and blend
3 - Do a JCM800 style higher gain preamp

[floridajack]

rjgtr - savings was not really a concern - more like cutting back on the complexity. i like the look of the lites and lite ii's - less wires and stuff!

zp - maybe "36watt medium?" i like the idea of the "blending," but would be satisfied with a single channel tmb. and i certianly don't need any more gain!! i play in a rock revival 3-piece power trio (i play bass and sing) and our lead player has stopped bringing his dsl and slant face 4-12 laney cabinet to our shows. only wants to use my 36watt

anyhow, i remove two tubes for smaller venues - that's why i want to install a lift switch for 18/36. i juat want to experiment with the nfb switch and the master volume - you know - can't leave anything as-is - but i don't want to mess with this build - it works sooooo well!!

i'll put a achematic together of my thoughts and let you all take a critical look at it.

until then, additional comments or suggestions are welcome.

floridajack

[zaphod_phil]

i like the idea of the "blending," but would be satisfied with a single channel tmb. and i certianly don't need any more gain!!

In that case you could simply parallel both triodes in the first 12AX7 to fatten up the tone a little.

[floridajack]

zp,

so i can:

1 - use one input that internally feeds into the two existing preamp circuits and "blend" them with the normal and tmb controls, (this emulates channel jumping) or:

2 - run the signal from the single input to both sides of the first preamp tube and on through the tmb stack, or:

3 - eliminate the normal channel, use half of the first preamp tube and have a single channel, tmb preamp.

is that correct?

floridajack

[zaphod_phil]

That's not quite what I said, but is also worthy of merit. In the options I suggested:

1 - Gives two slightly differently voiced preamp channels (based on the Richie 36W design) - but you would still need to jumper them or use an external ABY box, if you wanted to feed the guitar signal into both channels. However there's nothing to stop you physically connecting both inputs together inside the amp, and maybe having a switch.

2 - Gives two more distinctly different preamp channels (Treble and Bass) that you can jumper together and blend to taste, as in the original Plexis. The preamp is from the classic JMP 1987, and was the inspiration behind Richie's original TMB 18W preamp - http://www.schematicheaven.com/marshall ... w_1987.pdf

3 - The higher gain, single channel JCM800 preamp, http://www.schematicheaven.com/marshall ... w_2204.pdf
But you don't want that extra gain, so we'll forget about that one.

Now with the three you just suggested:

1 - Could be done with both of the first two options mentioned above. Just have a hard-wired connection between both inputs, possibly with a switch to allow you to separate them if you want.

2 - Just build a single channel TMB preamp. On the first preamp tube you just connect both sets of grids, cathodes and anodes together, so both triodes are paralleled together, like in a Matchless amp. This will fatten the tone slightly and give you a single channel TMB 18W.

3 - There's no need to waste one triode, if you parallel connect them as described in #2

HTH

[floridajack]

thanks zp,

it's all starting to take shape in my mind. i think i'll go for the single input to parallel preamp tube option (fatter sound,) master volume, no- feedback switch and 18/36 lift switch. i'll cobble together a schematic for reviwe and comments. even operating on two power tubes this design cranks!!

floridajack

[Graydon]

I don't remember if I mentioned this already so apologies if this is a repeat.

I just finished a Single Channel 36W that I built into one of my 18W S/C chassis. It was a tight fit but I did manage to get everything in there. It is basically an 18W normal channel into a 36W power section. My 36W power section is very similar to the early Vox AC30/4 (that is the 4-input AC30, not 6-inputs) so it is a little more "growly" than a typical AC30. IMHO, it provides a nice combination of Vox-ish tones and Marshally tones. The 36W still amazes me at its complexity and power. I really like this amp.

[Plexi]

My brother built one of the Liverpool amps, after the Ginger Wreck amp,or first one Ken built.
Its a 4xEL84 amp..and its very nice sounding. Single channel,and has the lift switch. I'm working on building something a bit different. Just ideas at the moment.

Richie

[floridajack]

hi graydon,

thanks for the interest in my project. do you have any photos or schematics of your 36 single channel? still looking for ideas for inclusion into my build.

hi richie,

same question - photos, schematics? i have mixed feelings concerning the tw-based amps. some sound pretty good, others get beat out by a standard champ or really stomped by a good 18watt. still interested is seeing other 36watt ideas. i have to keep reminding myself that vox, marshall and fender are only separated by $5.00 worth of parts and a soldering iron

floridajack

[Plexi]

same question - photos, schematics? i have mixed feelings concerning the tw-based amps. some sound pretty good, others get beat out by a standard champ or really stomped by a good 18watt

I know what you mean..and seen or heard some of those too. but if its built right,it will sound great..and ROCK.. And no way one of those amps will stomp on it at all. You need to hear one that is right..
He has some pics of his amp on the Wreck site. I think under Ginger clone.
But you can build about anything you want,even A VTB type channel,or single channel double power -18 vol tone.. And decide if you want a more 18 style PI or something different..

Richie

[Dave]

floridajack,

Here's my 36 watt schematic.

Dave H.

[Dave]

floridajack,

Here's my 36 watt schematic.

Dave H.

[zaphod_phil]

That looks good! It was about time someone published a 36W Lite design. A couple of quick questions. Was there a particular reason you used 1k cathode resistor in the PI, rather than the standard Marshall 820 ohms? Did you also consider doing your input jack arrangement like the Lite II, so that the Lo input would give you a single triode, and the Hi input, the parallel triodes? Also, what was the reason you used the more Voxish 220k/1k5 grid resistors on the EL84s rather then the usual 470k/8.2k? Not nit-picking, just curious. Were you aiming for something half way between a Vox and a Marshall maybe?

BTW, interesting to see another builder in the UK emerge from the woodwork!

Edit: I've noticed the drawing is labeled as a 30W amp - so maybe this was meant to be kind of a generic 30W amp, rather than a "Marshall" style 36W...?

[floridajack]

thanks dave,

your design clears up a lot of questions. i still think i want to insert a tmb stack in there. did you develop a layout?

zp,

tell me more about what you think this amp will sound like nd what your recommendations would do.

thanks everyone - this idea is coming together!

floridajack

[zaphod_phil]

This particular amp version has a low gain preamp, similar to an 18W Lite's and therefore isn't suitable to run a tone stack. What you will see is that both triodes in the first tube have been parelleled together, which is what you can do with the single-channel TMB you've been wanting to build.