Dual mono 1176 (more pics)

Thanks especially to mcs for scale-o-matic thingy :thumb:

Lundahl in-out, a simple 317/337 PS to power both channels and a slam setting at position 5 on the rotary switch. Otherwise a pretty standard build.

A rotary switch wiring guide will follow...eventually. All the wiring was documented during the building process. But first I've got to get through exams and the holidays too...

Very slick looking work. :wink: Well done!

She's a beauty !!! Nice work !!! :thumb:

Nice Work!
Finished mine today,too. Pictues will come soon.
A question: to use the masterlink function explained in the schematic, i just interconnected pin 7 via a switch from unit 1 to unit2.
the fets are matched within both units (meter amp and in reduction path) but not between the two units. so in my version the connection does not work. is the only way to use 4 matched fets? or did i wired something wrong?
answers welcome!
greetings

Yes, you have to to match 4 FETs (that´s at least what I did and I can´t complain about the result :green: )
:guinness:

AWESOKE work Mnats!!!!

Who did your front panel ? :grin:

great looking!

@djwig only the gain reduction FETs have to be matched.
meter amps will be calibrated anyway....so no need for matching these FETs.

steff

Very cool design!
I'm very looking forward your wiring guide :thumb:
Good luck at the exams and have a nice holiday, Mako

Kind regards

Martin

Very cool design!

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Who did your front panel ?

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Thanks everyone! I have to say again that the front panel/meter scale couldn't have happened without the mcs scale-o-matic and obviously there was a little "borrowing" going on as far as the layout. Why mess with a good thing? I though the mirrored idea some people have used would be too confusing.

Thanks also to Jakob, of course, for inspiration

Oh man, Steffen - it's not a patch on your gear, but thanks!

I'll try to work on the wiring page over the holidays.

A class act all the way!
:thumb:

Oops, sorry - I didn't really answer the question about the front panel. I made it using photo printing paper and an inkjet printer. Did the artwork in a drawing program. Cut out the two "panels" and stuck them on with spray adhesive. Coated the whole thing with matt acrylic spray.

It's all calbrated now except for the distortion trim which I'll do at school next week.


Found they were only drawing about 37.4mA each from the positive rail (no lights) so I put a smaller 30VA transformer in there to power both sides instead of the 50VA I had in there before. The grounding thing is like a black art to me though...I have the IEC connector wired to the chassis but the rest of the circuit is floating. Every ground point from the circuit I've tried to tie to the chassis has resulted in hum. Let it float and the whole thing is dead quiet!

Beautiful.... :thumb: :thumb: :thumb:

That really look great, Mnats. I had planned to build basically the same thing (with the two boards that I bought from you). I guess that I'll wait for your wiring update, though. It seems that you've already worked out the details!

Thanks,
Scott

Wow that made me almost poop myself. :grin:

Nice build!

I'm working on a similar dual-1176 (mnats boards) & am experiencing the same thing with ground loop hum.    It's nice & quiet if only one PCB is powered up, but with both boards powered, there's hum...  To eliminate it, I've had to disconnect chassis ground at PIN1 inputs, thus lifting all grounds from chassis...  It works, but not the best from a shielding point of view...

I think the proper solution is to isolate circuit & power supply grounds at the PCB & then star ground everything...  I'll work on it & will let you know what works...


MF

mnats said:

...The grounding thing is like a black art to me though...I have the IEC connector wired to the chassis but the rest of the circuit is floating. Every ground point from the circuit I've tried to tie to the chassis has resulted in hum. Let it float and the whole thing is dead quiet!

Click to expand...

After some star ground experimentation that yielded less than perfect results, I opted to just install a 2nd power transformer for the 2nd channel.  Worked great... both channels completely isolated, & hum free.  It also allowed me to ground each channel at PIN1 to chassis for good shielding.

Marc