Matamp/Electric amp schematics

[Nutjob]

are your pictures of a recently built matamp?

I wonder if the same guy is still doing the wiring.

doesn't look nearly as clean as the older stuff.

Those pics are not a Matamp, thats an Electric Amp.

[diagrammatiks]

ah got it.

[LabyrinthAudio]

I know it's against my own policy but I would definitely be down to listen to some clips/samples when the amp is done. Nutjob, you said something about a layout right? Aren't some of the components hidden under boards and connected in a 'point to point' manner? Would probably be a pain in the arse making that layout.

[Nutjob]

Actually I've almost got the layout done. If you look at the gutshot of the green chassis in the earlier post above, you'll see there's no "boards" just thin turret strips. Everything is pretty much visible and you can see and follow the signal chain quite clearly. Assuming I'm happy with the final results, I'll try and record some clips as soon as I get some free time.

[Nutjob]

AHAHAHHA, Jesus. This oscillation was driving me nuts. Try as I might, I could not eliminate it completely. Thought I had it licked, but all the fixes I tried either attenuated too much high end, or the overall volume... But... I had a breakthrough. I pored over all the gutshot photos I have, enlarging them in photoshop and trying to clear them up, and found something almost invisible in the photos, that I missed...

The shielded wire from the input to V1's grid, the shielding is connected to V1's anode and NOT to ground. Oscillation eliminated! F$%& me.

The thought of doing this never occurred to me, as most consider this to be a last-ditch means of eliminating oscillation. Curse you, Miller effect! But perhaps this is necessary to stabilizing this particular circuit, and integral to this amp's unique sound.

[Nutjob]

Done!

[sburck]

Looks like I found this thread at the right time. Decided to build an orange/matamp/electric style head, but I really started digging the electric master volume clips I found on youtube. Not that youtube can really give you an accurate idea of how an amp sounds, but the electrics seem to have more gain. My only concern is whether an electric can still capture the creaminess that the or120 has. Either way I look forward to clips / schematics / layouts for the electric, as I cant find that stuff anywhere after hours and hours of looking.

[Nutjob]

Looks like I found this thread at the right time. Decided to build an orange/matamp/electric style head, but I really started digging the electric master volume clips I found on youtube. Not that youtube can really give you an accurate idea of how an amp sounds, but the electrics seem to have more gain. My only concern is whether an electric can still capture the creaminess that the or120 has. Either way I look forward to clips / schematics / layouts for the electric, as I cant find that stuff anywhere after hours and hours of looking.

I have yet to hear the clone at full volume since my latest discovery, but I can say that it captures the Orange/Matamp tones, but with the capability of more gain, and more low end. And since I own both a Orange OD120 and a Matamp GTV-TC120, I will be able to A/B them.
I will repost the schematics and layout soon, with all the known component values, as well as notes about the shielded wire issue and other peculiarities with this circuit. Hope to also record some clips soon as well.

[sburck]

I have yet to hear the clone at full volume since my latest discovery, but I can say that it captures the Orange/Matamp tones, but with the capability of more gain, and more low end. And since I own both a Orange OD120 and a Matamp GTV-TC120, I will be able to A/B them.
I will repost the schematics and layout soon, with all the known component values, as well as notes about the shielded wire issue and other peculiarities with this circuit. Hope to also record some clips soon as well.

I took a look at this thread and I must have missed your preliminary schematic along with some comments. I am suprised at how the EA's switched to a FMV tonestack, and with the cathode follower pushing components behind it. It would seem to me that these changes are significant enough from the original orange/matamp's to prohibit the EA from doing good orange / matamp sounds, in fact I thought a lot of what makes an orange sound like an orange (or matamp) was the bandaxall tonestack.

Apart from that, is the triode before the phase inverter just an additional gain stage? Also, in the gt120 schematic, what is that triple way switch just after the input jack? I saw somebody on Gheert's website say that they thought the best sounding matamps had the FAC switch right after the input jack. This matamp schematic seems to have the FAC switch right after the first gain stage, and the triple switch after the input jack isn't wired to caps... What on earth is that? Also, what is that pot right after the master volume control? The EA's seem to have individual bias pots for each power tube while you have one pot that looks like it might have some sort of bias function between the two first power tubes while leaving out the second two. The whole section from the MV control to pin 5 on the power tubes is confusing to me. I compared it to the OTR120 and while they have some similarities in this section (PI to Power tubes) with their master volume wiring, your's seems a lot more complicated.

Lastly, how is work on the clone going? It's an interesting schematic you have come up with, and I'm looking forward to hearing clips and seeing the final schematic / layout. (these projects never really have anything "final", but you know what I mean)

[Nutjob]

Some of the preliminary schematic is rough, here's a updated schematic:

The BAXANDALL tonestack may have a bit to do with the Orange sound, but I think a lot of it is more likely the split-load phase inverter, and the high value coupling capacitors. This update has the individual bias lines shown, and some edits to the Deep/FAC switch and Presence pot. also, the earlier one had the "presence" in the wrong spot, should be right before the MV. This is like the Vox 'cut" control(but wired to pot backwards), basically shunts the same frequencies that the standard presence control deals with. Same function, different placement. the triode before the phase inverter is a direct-coupled driver stage, I would assume is primarily to boost the signal after the "loss" from the tonestack, and in these circuits, does a great job of driving the PI into distortion.

From what I can see with the EA's master volume control, they run parallel lines from each of the dual 1M pot's wipers to the power tubes, and halve the values of the post-MV coupling caps(4x.022uF) from the pre-MV values(2x.047uF).

Your post was a little confusing because you switched gears to GT120 schematic in the middle of all that... took me a sec to figure that out. The 3-pole 4-position switch in the GT120 schematic is the Matamp drive control, used on the early Matamps, and Orange Matamps. On the front panel the 4 positions were labeled STUDIO, STUDIO BRIGHT, STAGE, and STAGE BRIGHT. From what I can tell, this switch partially bypasses(or not) the first gain stage(lowering the gain and volume), with the addition or subtraction of a bright cap, thus the 4 positions.

Also, I dont know if I can say the FAC necessarily sounds better right after the inputs, its effect certainly is more pronounced, though. Personal preference, I say.

Clone is getting buttoned up this week, I'll try to have at least some video of it on youtube by next weekend.

Another note I keep forgetting to mention: The EA has an unused triode in V1, which is not grounded or wired to anything.

Whew, good points, all. Any other questions?

[sburck]

Yes, 1 more! Is the 1m pot right before the second gain stage the fuzz control?

Took a look at my post and it does look a bit confusing, that's what happens when you try to write after peering at schematics for hours directly after working on engineering assignments for hours

[Nutjob]

Yes, 1 more! Is the 1m pot right before the second gain stage the fuzz control?

Yes. That's the fuzz control.

[xxxslayedxxx]

interesting a lack of Bax stack in this amp and the inclusion of an FMV as well as the DC CF and DC cathodyne.

[Nutjob]

Yeah, it's pretty neat. That dc cf is pushing less gain and higher current into the less-lossy FMV tonestack pushing the PI harder than the Orange/Matamp circuit. So you get more of that fuzzy fully cranked Orange tone at all volumes. At least that's how I see it.

[sburck]

Any idea what the voltages are supposed to be at points a-e? I doubt you have the same PT as they are using in the Electrics, but none of the orange or matamp schematics have marked voltage values either. I'm seriously thinking about building something similar to this, and I wouldn't mind shelling out the cash for a MM OT, but I'd rather just use a Hammond PT or something in that price range, so I would need some voltages to spec out a transformer and possible change some of the resistor values in the PS.

I was also thinking as to whether there is a way to incorporate an effects loop similar to the or120/gt120. Theirs runs right between the second and third gain stages, however the electric puts the CF right after the second gain stage and runs the third gain stage input directly out of the tonestack, so it seems that this part of the circuit is totally different from an orange/matamp and you would not just be able to wire up an effects loop in the same manner.

Lastly, your biasing scheme in the schematic. Do you have the same bias section of the PS as they do in the or120/gt120 schematics (with the 22u/63v caps and the 1k + 22k resistor)? You seem to have 4 independent bias pots in your design. Where are these relative to the schematic and the omitted bias section from the power supply.