Two channels with effects loop. Can be run either channel 1 or 2 or both. Footswitch. Parallel tube effects loop. Pentode/triode switching.

Note the use of the perfboard. Note the push-in terminals that allow easy component swapping (Mouser # 574-T42-1/C, 100/$8.31). Note the use of Belden 9396 shielded wire (it's the very bestest!). Pots can be from anyone, but many are from Mouser. Most caps are common, but I did use some of the rediculously overpriced LCRs because I happen to have a couple. Switching is by Vactec LCRs, but king-man badass amp masters (like yours truely) can do the switching with cheaper relays without noise.

Note how the wiring to the preamp tubes is done through holes in the perfboard above those tubes to the upper side of the perfboard. Some power supply wiring is underneath, but the portions of the circuit that has to do with tube operation, EQ and interstage coupling (and, thus, tone) is on top.

It's been modded a few times, so it's kinda busy.

Chassis is salvage. Preamp wire color: Red for plate, green/blue for grid, orangeish for cathode. The flash washed out the color a bit.

whatcha got in the power section 6L6s or EL34s. Does it sound similiar to anything are is it a beast on its own. Like more fender like or more marshall like. You running it through 4-12s. What is she putting out 50 or 60 watts.

sixty4fairlane

Right now, with EL34s and a Marshall-esque circuit, it sounds kinda Marshall-y. It's got a stiff power transformer, and a Triad PA output trans. Puts out about 65 watts clean.

It's set up to allow easy circuit mods. That is the point of the pictures. General construction styles for prototyping.

Also what kind of transformers would you ideally reccomend to get some of the big bottom ampeg/hiwatt and some of the marshall plexi flexibility ? Is there a happy medium someplace ? Have you ever tried creating a "sag" circuit too emulate overworked transformers whilst still using big 'uns ? Are you familiar with the "mavin peal sag circuit" ?

They are LDRs. Light Dependant Resistors. The thingie has a LDR and a LED and make a nifty way to do switching. Relays are cheaper.

I do do gimmick circuits. Other folks do, and that's fine. If sag is needed, I would rather design the circuit to do that, than make up something to impart it.

I wish I knew enough to ask an intelligent question Tom.

Wish I coud hear it cranked ?

Any new music to recommend? My GF saw PJ Harvey at the Knitting Factory last week and said it was a great show.

You can come by and clean the bench for me, if you like.

What difference does it make ? and also I was wondering about a temporary sag circuit in my project too see if I like it .I think the tone lizard may have one schematic.
Once and for all are people who claim too hear differences in capacitors full of shit ? and resistors too for that matter.

Older ones don't care.

Sag circuits come under the same concept as the diodes we were talking about. You gotta have a working amp first.

All this fun stuff can be added, but it helps that your amp is running and you are comfortable and familiar with it. Then, the subtlties of any change becomes more obvious.

but no 4x12 BOO HOO ! not even a 2x12 ! It's hell having an amp that you can't even fucking listen too ! I'm going too ebay .

n/m

I've had several "junker" amps that I've used to tinker with and to try things but I've just never had the gumption to build one totally from scratch, it does sound like lots of fun.

I was just sort of wondering what voltages you have on the first gain stage in the amp. From my experience I've found that I like higher B+ there than many amps because it seems to make the amp more touch sensitive and easier to control esspecially if you've only got one channel.

I've got 2 Marshall 50watt 4 input heads that I've done this way, I've increased the preamp voltage by about 50% or so, seems to work, but I like that kind of amp, nothing but a volume control on the guitar and different playing style needed to change the sound.

Neat... Now you need to knock together a 2x12 test cabinet try some low wattage Eminence speakers, I've got some and they seem to sound great with an amp in that power range.

I usually go around 220-250 around the front end if a crisp sound is wanted. I know what you mean about the voltage. Of course, you get to a point and it just turns to buzz. Ick. Add high voltage with multiple gain stages and you have a buzz saw. KnowhutImean? Usually, I start out with a concept of the circuit and the voltages, and then I let the sound tell me where to go. When it's right, it's right, regardless of the voltages.

Be the amp.

DO ya jumper the two channels on those marshalls. I've seen this done and wondered why ? What kind of sound you get by jumpering between them ? Dave, Tom, whats it all about ?

sixty4fairlane

Jumpering the channels gets both preamps working, and results in a larger signal going into the tone stack. More voltage, more gain, more signal hitting the grids of the outputs. So, you get more distortion. You can do the same on many non-reverb Fenders. As long as the preamps give you an in-phase signal, you can do this.

Most of the time, yes Myles uses the amp with the channels jumpered together. He sets it with the treble channel on about 4 and the bass channel on about 2 or 3. My amps both had a master volume pot added after the preamp section, similar to the way Marshall did it on the master volume amps. It's silly really because the 4 input top sounds terrible if used master volume style. I've left them like that however because it's sometimes handy to use it to "thin out" the sound a little, you just turn it down a tiny bit and it tends to roll of a small amount of bottom end. We use the amps into a Power brake most of the time anyway to help control overall levels and how hard it hits the cabinet.

Jumpering the channels together adds the gain of each channel together. It's not really like the master volume amps where the channels are cascaded and the gain from one stage to the other is multiplied, it's just not that kind of preamp distortion. It just gives you a bit more control with whatever guitar you happen to be using.

how simple have you made one and howdit sound ?

Come again?

can anybody get the brown sound with a lead voice like we listened too last night ? that was a 60watt class ab fixed bias rig.

This is about "trainwreck " ken .

Les Krygier: I saw Ken's ad in a local musician's paper and had heard about his reputation, for hot rodding Marshall amplifiers, by word of mouth. I always had at least six Marshall Super Lead, Model 1959, 100-watt heads and scores of cabinets on hand. The sound I was going for at the time was the tone on the first Van Halen album.

Ken dialed that one right in, but said he though he could do better on the solo tones if he modded an amp just for lead work. With six heads I had nothing to lose, and within a few weeks he had developed a one channel, one input pre-amp and phase inverter for one of my heads. The modified amp had more gain on two than it did stock on ten. It was very thick and very loud, and harmonics literally jumped out of it.

Let's get the cake, first.

I'm responsible for concepts and ideas , you're responsible for hard data !

I looked this up so we could have more Tom pics. To go along with the ampeg pics. More cool amp stuff.