Dukane 3A235 inductor EQ

[rackmonkey]

I just got one of these in for repair. Very little information out there about it. But it's an interesting unit.

Anyone have a manual or at least a schematic?

Thanks

 

[pucho812]

A quick trip reviled this reverb listing.

It has a page in the photos of what looks like it’s from the Manuel perhaps it can help...

https://reverb.com/item/3471566-dukane-3a235-inductive-analog-24-band-mono-parametric-eq

 

[rackmonkey]

Yep, looks exactly like the one I'm looking at here. It's funny, I found that same announcement about the unit in an old dB Magazine from 1973. It's about the only artifact about it on the interwebs.

Shouldn't be too hard to trace out if I have to, but if anyone is sitting on a schematic it'd save me a lot of time.

Thanks for the pointer, Pucho!

 

[pucho812]

Yep, looks exactly like the one I'm looking at here. It's funny, I found that same announcement about the unit in an old dB Magazine from 1973. It's about the only artifact about it on the interwebs.

Shouldn't be too hard to trace out if I have to, but if anyone is sitting on a schematic it'd save me a lot of time.

Thanks for the pointer, Pucho!

Yeah I hear you. I tried. But will try again and see if I can dig up any more info.

 

[rackmonkey]

Appreciate it!

 

[mjrippe]

Just checked my files and no luck.  Tube DuKane stuff is generally not hard to find - I have a lovely 1949 Operadio catalog with specs and schematics - but the solid state stuff is more hit or miss.  From the looks of it this piece will have a discrete transistor circuit for make-up gain.  If you get stuck I could dig up some other pieces from that era that may use similar designs.

 

[Ricardus]

Interesting. Following.

 

[rackmonkey]

Thanks, Mike. It’s not passing signal. Not a hard one to track down. I’m more interested in what this thing sounds like and what could be done with it. Late 60s/early 70s swinging input EQ with +/-14 dB boost/cut from 63 Hz - 12,500 Hz with plug-in, individual filter modules is pretty cool on the surface of it.

Since there’s interest I’ll post what I find out.

Just checked my files and no luck.  Tube DuKane stuff is generally not hard to find - I have a lovely 1949 Operadio catalog with specs and schematics - but the solid state stuff is more hit or miss.  From the looks of it this piece will have a discrete transistor circuit for make-up gain.  If you get stuck I could dig up some other pieces from that era that may use similar designs.

 

[goldstache]

I have drawn out the circuit if you still need it.
-joe

 

[gyraf]

..would definitely be interested in seeing this also!

/Jakob E.

 

[Ricardus]

I have drawn out the circuit if you still need it.
-joe

Yes. Please post.

 

[rackmonkey]

Agree. Please share what you have.

 

[goldstache]

Sorry, I don't post much, so I figured I'd get an email about any further correspondence. Ooops.
Also, noticed that I may have misspoke, or my own hand scrawl was titled wrongly. Lol
Anyway, heres' what I got. It's just the standard feedback based design. I didn't take measurements on the inductors, but there were trimmed, and kinda scaled based on freq

 

[goldstache]

 

[goldstache]

This was the slice of per channel passives. Gave up after a few bands, but ya get the picture. I also mocked up to try it, it worked. Dreamed of making something similar as I keep a stereo pair on the stereo. Let me know if ya got any cool ideas or info. I kind of dig em. Also, that jumped input resistor in my drawing was to get back to unity input. It neuters the input pretty hard, when I did hard bypass input to output it was obvious that it was cutting gain when in path. But the series resistor was the stock one in to amp.

 

[gyraf]

Thank you!