thread: ART Tube Opto 8
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Old 13th February 2020
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Here for the gear
 

ART Tube Opto 8

Does anyone know where I can get a schematic for an ART Tube Opto 8? I've seen this model mentioned here....tube subs and mods....but schematic? I contacted ART and they say its their policy NOT to provide schematics for current production units. My Opto 8 has some crackling in one of the mic preamps but the PCB layout doesn't lend itself to easily understanding the circuit. I started drawing a schematic myself (after finding none on the web)....but the ckt layout is screwy,the PCB is double sided, there's a mix of SMD and through hole parts, and a number of the traces are obscured by the components. After a few weeks, I made it thru the preamp and line level audio ckts...but lost the signal path somewhere in the digital stuff. I tried working backwards from the output jacks...and drew schematic of the analog output ckt.

I probably know enough about the ckt to to fix the noise problem....but having put so much time into this thing...it'd be nice to have a full schematic.

I looked at all the ART schematics I could find online....and I see a number of similarities to the Opto 8.

Incidentally, my Opto 8 has several obviously bad caps (bulging tops) and a number (like 20) of high ESR (5 to 50 Ohms) caps. These aren't the cause of the noise, but I wouldn't be surprised if the THD is worse than spec'ed.

BTW, anyone have a preamp noise problem with an Opto 8. What was the cause? The IC, a transistor, resistor...etc.

If no one has a schematic and wants one, I can email what I've figured out so far...