DIP8 sub for 2520?

[jwhmca]

I took the 2520 off my API 212L and found a DIP8 area underneath. I would like to stuff it with something to test the rest of the card. Any suggestions as to what will work?

 

[gemini86]

First you need to figure out if it is a single or dual channel pinout.

Second, you'll be able to test the circuit for the most part, but a little ic opamp won't drive the output transformer on its own.

 

[plumsolly]

NE5534 should work. You can verify the pinout is compatible by checking which pins on the DIP socket are connected to which pins on the 2520 socket.

Best,

Ben

 

[gemini86]

5534 will need a compensation cap. Just bend those pins upward and solder the cap directly on them.

 

[plumsolly]

5534 will need a compensation cap. Just bend those pins upward and solder the cap directly on them.

Does the 120pf cap across the feedback r in the 312 help with stability at gains below 3?

Best,

Ben

 

[gemini86]

The compensation cap is needed directly between pins 5 and 8 of the ic. In the 5532 (dual channel version) this is built into the part.

 

[plumsolly]

The compensation cap is needed directly between pins 5 and 8 of the ic. In the 5532 (dual channel version) this is built into the part.

Right. I am just curious if the 120pf cap across the feedback r, which brings gain at very high frequencies toward zero, also helps with stability.

Best,

Ben

 

[jwhmca]

getting the pinout and comp cap is easy... what about driving the transformer? Just disconnect for now?

 

[plumsolly]

getting the pinout and comp cap is easy... what about driving the transformer? Just disconnect for now?

Don't need to. It is fine for testing to see if it works. You might have slightly more distortion than you would with a 2520.

Best,

Ben

 

[envelope]

Analog Devices OP27G sounds nice and will drive a 600Ω transformer.

from the DATASHEET:
The output stage has good load driving capability. A guaranteed swing of ±10 V into 600 Ohm and low output distortion make the OP27 an excellent choice for professional audio applications.

 

[joaquins]

Analog Devices OP27G sounds nice and will drive a 600Ω transformer.

from the DATASHEET:
The output stage has good load driving capability. A guaranteed swing of ±10 V into 600 Ohm and low output distortion make the OP27 an excellent choice for professional audio applications.

I'd use them in servo apps, dead zero in my meter at 0.1mV definition, would love to have a microvoltimeter but i dont...

JS

 

[gemini86]

But isn't the 312 output wired 1:3? That would result in the opamp needing to drive close to 60R.

 

[JohnRoberts]

Blasphemy... 

JR

 

[plumsolly]

But isn't the 312 output wired 1:3? That would result in the opamp needing to drive close to 60R.

1:2, I think. But this only for testing, right, before the 2520 goes back in? And he will probably will not load the output with 600Ω. I wouldn't think it will blow up the chip, just specs might suffer some.

Best,

Ben

 

[gemini86]

But isn't the 312 output wired 1:3? That would result in the opamp needing to drive close to 60R.

1:2, I think. But this only for testing, right, before the 2520 goes back in? And he will probably will not load the output with 600Ω. I wouldn't think it will blow up the chip, just specs might suffer some.

Best,

Ben

Agreed. It's really of no advantage to put anything but whatever works in there... We still haven't found out if it's a single or dual channel pinout...so there's that.

Kinda strange really... I took the 2520 out of my friend's 212L to replace the burnt out one in a 225L that we needed to finish a tracking session. I don't remember there being a dip8 socket under there.

 

[jwhmca]

It's there alright...

 

[gemini86]

That sure looks like it's a 5534 pinout... even has the comp cap between 5 and 8.

 

[pucho812]

I don't know of any 2520 and or clone that is a duel op amp.

 

[jwhmca]

Do I need a comp cap? It seems like the 5534 is supposed to be stable with gains greater than 5?

 

[Harpo]

Do I need a comp cap?

Yes for NE5534.

It seems like the 5534 is supposed to be stable with gains greater than 5?

Yes. You do the math for min.gain setting 1+20K/25K2.