Phase 90 op amps?

[jaysg]

I'm building up a Phase 90 and I need to either order some op amps or put in sockets.   Are there are better op amps for this than the TL071 ?

[DougH]

Yeah, TL072. It's "1" better...

Seriously TL071/72 sounds fine in this circuit.

[petemoore]

  TL072 is Dual OA
  TL071 is Single OA.
  Pinouts on the board assigned to a dual layout won't accomodate a single oa, the pinouts are completely different. Choose the opamp, then the layout or vice versa.

[Dai H.]

AFAIK early one used six single (741), the later version had slightly different circuit and used three double (TL062)

[jaysg]

I had either a Script or an early block logo unit...don't remember...the box showed the script model.  Anyway, having foolishly sold it in the late 70's, I borrowed a '78 (or thereabouts), and it sounded very different.   I didn't like it at all.  I'm fairly sure the one I owned, had the 741s in it.   There was some noise or distortion.   I believe that was from the FETs.

pete -- I think DougH was making a joke with the part numbers.

[petemoore]

  I built one with duals, TL082, different duals tried.
  Then I got a kit with LM741's, not all that noisy, definitely a different sound too. How much of that was attributed to...everything else...[tolerances and layouts mostly, also a 'depth' knob I like, I used film caps on both], I'll never know for sure. 741's I think are a little less 'pristine' and that's part of the difference.

[DougH]

I seriously doubt you're going to notice much difference between op amps with this circuit. Maybe - but it will be pretty subtle.

Most of the sound difference between "script" and "block" Phase 90s can be attributed to the presence/absence of the feedback loop with the 22k. The feedback loop is responsible for the "midrange" and "distortion" sounds that people don't like.

Edit: I almost forgot- here's pics and soundclips of a Phase 90 I built with TL072 and no feedback loop (like the script):

http://www.aronnelson.com/gallery/main.php/v/DougH/phaser/

I used a Tonepad PCB, which makes it real easy. I spent a lot of time with this on the breadboard before I built it. In the end, all I did was leave off the feedback loop and bump up the gain of the output stage slightly to keep the volume consistent with the bypass volume.

[Baziiil]

I've got a question. Which transistors did you used in p90 ?

[DougH]

I used 2n5089 IIRC.

[jaysg]

Really?  That's an NPN, not a JFET.

[DougH]

Yeah, that's for the output stage.

For the JFETs I used some matched J201's.

Sorry, when people say  "transistor" I automatically think "bjt". I forgot all about the JFETs...

[Dai H.]

mine is an early Jim Dunlop MXR with the later circuit (and 3x TL062) which I modded to earlier cct. thx. to info found on the 'net. I've tried swapping 1458s of different brands and the original TL062, and there is some difference but not gargantuan. I like the way it sounds now better but need to figure out how to lower the (LFO?) thumping. Also Dunlop is making the older version again called the '70-something(?) Script(?).