Phase linear 3500

[philinear]

Hi,

I'm currently recapping a 3500 phase linear preamp.
Are there any interesting mods or upgrade to be done on this unit?

cheers

 

[laatsch55]

gOT A SCHEMATIC?? wHAT DOES IT HAVE FOR OP-AMPS?

 

[philinear]

I have a pl3800 schematic which I believe is the same.

Op-amps are NE5532 and 5534

 

[laatsch55]

Is it a 3500 Ser II??

 

[philinear]

Yes, the 3500 pre only exists in series 2

 

[laatsch55]

It has more in common with the 3300 than the PL3600/3800. Complete different pedigrees....

 

[philinear]

ok, thought it was more like a 3800. Didn't start quite yet, that's why I wanted to know if there was some improvement to be done on it

 

[laatsch55]

That's where a schematic would come in handy...

 

[philinear]

I'll check if i can find it then.

thx again, you're really helpfull

 

[laatsch55]

There a r e some folks who might argue that point...

 

[philinear]

I get from an ex Phase Linear tech that the 3800 shares the same electronic as the 3500 so here's the schematics. It definitely looks identical

 

[Gepetto]

I get from an ex Phase Linear tech that the 3800 shares the same electronic as the 3500 so here's the schematics. It definitely looks identical

Couple of points Lee

5532 and 5534 should not have +/-20V powering them. Theyare probably only saved by the 100 ohm resistors in series with each supplyline feed. They are meant to run on +/-15V.

The 5534 is a decompensated amp and hard to get a replacementfor.

The 5532 is easy with an OPA2134 once you fix the +/- 20V supplyproblem.

That is easily fixed with a couple resistor value changes.

Change R2, R3 from 1.82K to 1.33K

Z1-Z4 to OPA4134.

The way this is done by design degrades crosstalk between the L/R channels. Nothing you can do about that.

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[philinear]

Thx Gepetto, that will come in handy I'm sure