What the Hell is This????

laatsch55

laatsch55

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What is this board for?? It'ss mounted to the inputs and the pots connect to it also....it's one of the Handley 700B's....
 

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I don't know Mike. It's powered by both rails...
 
Lazarus Short said:
​It's a pre-opamp.
Click to expand...

I agree with you Laz as this was my first inclination before looking up the RC4560 spec sheet.

From the spec sheet:

"The RC4560 integrated circuit is a high-gain, wide-bandwidth, dual operational amplifier capable of driving 20V peak-to-peak into 400W loads."

The front panel pots would change the output gain that I'm guessing went directly to the controller board.
 

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Nice job, Laz!
 
Making up for signal loss on long cable runs?? Where's BD when ya need him??
 
laatsch55 said:
Making up for signal loss on long cable runs?? Where's BD when ya need him??
Click to expand...

No shit - where's BD? He could shed some light on this with his real world experience.

Derek - have you heard from George recently?

It could be a long ass cable run with a significant drop in voltage but this op amp could easily overdrive the controller board. I would ass-u-me that this circuit was designed to limit the output relative to the amplifier controller board input parameters.
 
laatsch55 said:
Could have been an instrument amp conversion?
Click to expand...

It could be a simple preamp that is driven by the sound board equipment. That would be one way to limit the amount of hardware you'd have to drag around and setup. The front panel pots could be adjusted for each amplifier to get the right sound from the speaker stacks. This is all conjecture on my part.
 
laatsch55 said:
What is this board for?? It'ss mounted to the inputs and the pots connect to it also....it's one of the Handley 700B's....
Click to expand...

Converts balanced input via phone jack to single ended for industrial applications...
 
I saw that too, probably a few of the amps have them installed
 
Interesting that its 1/4 jacks for balanced. I think the standard is XLR connectors, though I don't see where you'd fit a pair of those on a PL 700. My Pro 700 has 1/4 jacks, but its the standard unbalanced connection.

A BALUN board could be a handy thing to have around, especially paired with either an UNBAL converter or a transformer wired for that duty. Never know when you might need to run an interconnect cable 100 feet or so.
 
NavLinear said:
No shit - where's BD? He could shed some light on this with his real world experience.

Derek - have you heard from George recently?

It could be a long ass cable run with a significant drop in voltage but this op amp could easily overdrive the controller board. I would ass-u-me that this circuit was designed to limit the output relative to the amplifier controller board input parameters.
Click to expand...

Yes I have been in contact with him. that board to help long XLR Cables makes sense.
 
Balanced inputs

Hi all
This looks like a balanced to unbalanced inputs convertor. Used with line level equipment.
I am starting a 700 build with one of Joe's full kits. Got some good stuff coming from Dennis as well. I was considering adding a balanced input to the amp . I found these kits which I believe are a more modern form of your mystery parts.
Check out the following site
http://www.diyrecordingequipment.com/balanced-input-output-manual/

I picked up an old Rane BB44x balanced to unbalanced transformer set box so I am going to use that instead as I am feeding balanced inputs from a dbx speaker management processor
Still interested in these boards though.
 
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