Schematic and BOM avaiable at OSH Park.
Looks like a very interesting Matamp/Orange amp emulator running mostly at almost 36v with an active speaker simulator(?) and a "Mode" switch for two tonestacks. Each being at different locations in the circuit.
Damn you're cranking out the Dunwich stuff. I wonder how this compares to the DA-120. Any plans/info for a layout for that?
ReplyDeleteSadly not enough info for a layout(yet). But circuit wise it seem to be a different beast than Apostle. I know that there is MOSFET transistors, a TL074 quad op amp and a charge pump in it. The tonestack looks like stock Matamp and it has a FAC switch. Very interesing circuit! But more information is need...
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ReplyDeleteStarted working on this for fun, is there any reason you skipped grounding on pin 5 on the LT1054? Also D7 is added as protection diode when not in schematic? - is best way to approach this one following schematic on osh park i guess? If you made some minor errors
ReplyDeleteIf anyone else is trying give me a hint - also cant see any reason for the 10uF to be bipolär - Must just be a schematic mistake, might aswell have it polarized - or am i wrong? /
ReplyDeleteThanks for spotting the grounding of pin 5....never seen that configuration before.
DeleteAs for the 10uF cap. The BOM actually specifies it to be a film cap which would end up HUGE! There is room for it on the board (I think!) but I see no reason using a bipolar electro or a MLCC instead. But if you want to live dangersous and using a normal electrolyctic cap, the positive leg "should" be facing south.
No worries, iam amazed how you can draw em up so fast with so Little errors.
DeleteMaybe it is because polarized usually have a 10% span - and bipolär works better as filters, almost looks like a feedback loop, if so might be best to create a bipolar out of two 22uF - oh well socket and try. Cheers
I have the pcb and I can't get working yet
DeleteOkay Anders - I built this up today and I hesitate to say it is verified. After much fiddling with the jfet trimmers I got all the pots to work sounding "right". The gain knob acts much like an on/off switch very early in the sweep so I added an 82k resistor to leg 1 to limit it a bit. I also removed the FAC switch since It functions, but at higher gain setting, it gates. I suspect that this may be because I have all of the 2n5457s biased kind of hot. But everything else sounds really, in my estimation, great! Loud as hell and very amp-like. I'll post a demo on the Capitalist Death Cult Instagram tomorrow and let you be the judge. I also want to build up the PCB since I have one.
DeleteThanks for giving this one a go, Chris. Looking forward to hear your demo and how your PCB version turns out. I won't tag it as verified yet, this layout might work as intended but you never know, those J FETs can be a PITA...
DeleteTried a second pcb and still can't get it working right.
ReplyDeleteI also tried the PCB from GCI and it didn't work. However this circuit works like a charm.
DeleteMark it verified. Very loud, but versatile with gain and boost adjustments.
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