Matamp/Electric amp schematics

[Nutjob]

Seems like it's still the same boost control wiring as earlier?

Slight change. Nevertheless it should work as it's supposed to.

[Beefcake]

Tomorrow is the first time I'm taking it with me to a rehearsal, I'm hoping it's gonna blow everyone's balls off

I'm kinda wondering if it'd be possible to add a passive effects loop to this design without completely screwing it up.

[Nutjob]

Tomorrow is the first time I'm taking it with me to a rehearsal, I'm hoping it's gonna blow everyone's balls off

I'm kinda wondering if it'd be possible to add a passive effects loop to this design without completely screwing it up.

You can, but it will be like the Orange OR loop that pretty much sucks. Id shoot for a nice transparent solid state fx loop (gasp!)

[jussi]

Thanks for the schematic. How is it going nutjob, haven't seen new videos or fb updates from you in a few months?

I built amp with preamp like this but highly modified. Sounds very different but maybe heavier (maybe it comes from the P90s?).
Power amp has two JJ 6v6s

Some ghost notes at full volume.. layout: http://s2.postimg.org/qjvzs6861/guts.jpg

I have different caps in the FAC (wider range) and V1 is parallel with resistors changed for almost same gain (less noise?) and bypass cap increased to 100 uF. Biggest change is the tone stack replaced with a one knob tilt control. Also I don't know how the preamp voltages should be - i'm running them very hot atm. VERY nice cleans: http://soundcloud.com/jussi-poikkeus/kulkija

I'm not sure if it sounds very good. Badass? yes, but maybe too much?

[jussi]

Maybe lowering the voltages would make it more fuzzy? Currently I have these voltages for the points C,D,E: 418, 373, 307

[rocket88]

Beefcake, I'm confused at the reasons for the things you said need to be changed, and how to actually change them in the schematic. I looked at Nutjob's new schematic, but I didn't notice a huge difference, which I think confuses me more. One question when it comes to wiring P2P style, do I wire it so that it looks like the schematic, basically like it when I build something on breadboard.

I'm so glad to see that others have built this monster, it's given me more confidence to undertake it myself as my first P2P amp build. So, I figure the time has come for me to start ordering parts, to get ready. For instance, I saw Electric is starting to sell parts, and they want like $500 for theirs, while the others I've found are in the $200-$300 range.

Does anyone have good sources for parts at reasonable prices? For instance, I've been looking at transformers, should I be looking at getting one for an old orange or something else, and there seem to be different levels, and not sure who to avoid. Cause I figure it should cost somewhere between $500-$1000, based on looking at kits for other amps on the market, and if most of the parts can be ordered from one company it will help immensely.

What about the case dimensions, resistor wattage, cap ratings, etc.? I'm hoping someone essentially might have/make a parts list for this. I'm sure some parts supplier would gladly take a look at the schematic and put together the parts, but I don't want to just send the schematic around. Thanks in advance guys, and Happy New Year.

[Beefcake]

I'm not sure if it sounds very good. Badass? yes, but maybe too much?

Do you have a schematic of what you ended up with after your changes? It does sound extremely heavy, but you're right, it might be a tad too gainy.

Beefcake, I'm confused at the reasons for the things you said need to be changed, and how to actually change them in the schematic. I looked at Nutjob's new schematic, but I didn't notice a huge difference, which I think confuses me more. One question when it comes to wiring P2P style, do I wire it so that it looks like the schematic, basically like it when I build something on breadboard.

What changes are you confused about specifically? Also, when you're wiring it, I'd honestly try to replicate the PTP scheme EA uses for their amps.

Also, good news, I've been going to rehearsals with it now every week since that last post and it still sounds great. Just that first chord I strike in the practice room brings a smile to my face :-)

[Beefcake]

On a completely different note, I wonder what the differences are between the Master Volume Unit we built, the Volume Unit and the Power Unit.

[rocket88]

Do you have a schematic of what you ended up with after your changes? It does sound extremely heavy, but you're right, it might be a tad too gainy.

What changes are you confused about specifically? Also, when you're wiring it, I'd honestly try to replicate the PTP scheme EA uses for their amps.

Also, good news, I've been going to rehearsals with it now every week since that last post and it still sounds great. Just that first chord I strike in the practice room brings a smile to my face :-)

What I'm confused about is the images you posted, were they what should be done or just showing the location for the changes? Also, the reason you mentioned reversing the bias, like how to and why? BTW, you have no idea how much I want to get this thing built and not just run my guitars through it but my basses too. I just hope my mesa doesn't get upset and jealous once its done.

[rocket88]

On a completely different note, I wonder what the differences are between the Master Volume Unit we built, the Volume Unit and the Power Unit.

Oh and I forgot, I looked at the power unit, volume unit, and the master volume units. I think the difference is the controls you have. The master gives you 7 controls, volume gives you 6, and power unit only 3. I think the internals are all the same though.

[Beefcake]

What I'm confused about is the images you posted, were they what should be done or just showing the location for the changes? Also, the reason you mentioned reversing the bias, like how to and why? BTW, you have no idea how much I want to get this thing built and not just run my guitars through it but my basses too. I just hope my mesa doesn't get upset and jealous once its done.

The images I posted were things that needed changing. The latest schematic that nutjob uploaded should be correct.

The thing with the bias supply specifically was that it was supplying a positive voltage, while a bias voltage should always be negative. That's why the diodes and electrolytic capacitors had to been turned around. I built it at first without noticing the positive bias voltage supply and you end up red plating your power tubes almost immediately after startup.

Oh and I forgot, I looked at the power unit, volume unit, and the master volume units. I think the difference is the controls you have. The master gives you 7 controls, volume gives you 6, and power unit only 3. I think the internals are all the same though.

I'm not completely sure, but I think the other models have less preamp tubes than the MV120.

[rocket88]

I'm not completely sure, but I think the other models have less preamp tubes than the MV120.

Got it. I just took a look and saw that the changes were there, and I get it. Using this schematic I assume its for the el34 tubes, since its marked as 120watt, is it possible to use change it to use kt88's and have 180watts or is it completely different? BTW, what transformer did you use? Was it for an older 120watt orange/matamp amp? I really don't want to spend $320-$340 to get it directly from electric amp, when most transformers from Mercury Magnetics are about $100 less.

I just checked their site again, and each amp has the same power levels, but not sure about the preamp tubes though.

[Beefcake]

I cheaped out and used a Hammond 290HX PT and a Hammond 1750R OT. If you use the 290HX, you'll have to make some adjustments to the bias circuit, because the bias tap on it is 100V instead of the 50V expected in the schematic.

On another note, you can see my terribly wired prototype here. The AutoCAD drawing is for a new scratch-built chassis that I'll rebuild it in with better wiring and a nice ampsleeve.

[Beefcake]

I'm thinking of using unused triode V1B as an fx loop buffer.



I'm wondering if I'd best insert it right in front of the phase inverter between V3A and V3B or have it after the tone stack in front of V3A. I'm guessing that I might as well lose the 1M return level pot, or maybe replace both of them with trimmers.
Is anyone seeing any issues I might've overlooked?

[Beefcake]

Got me a couple of sweet chassis made :-p