AM97C11 Nat Semi Monolithic JFET(ross phaser) Discontinued?

[Kleber AG]

If so is there some equivalent/replacement for that ic in the Ross Phaser?
I'm thinking about building it, well I'm searching for a different, easy, non distorting nice phase.....

Thanks
Kleber AG

[czech-one-2]

Old bump....
Does anybody know of a part for part equivalent?

[Kipper4]

Tonepads P90 uses 2n5952s matched
go take google at it

[czech-one-2]

Hi, I'm trying to repair a voltage dameged ROSS phaser. So I'm wondering if there is an equivalent IC available?

[Kipper4]

IC gotya
tonepads p90 uses a TL072. not sure without seeing a schematic though.

[czech-one-2]

http://home-wrecker.com/ross_phaser_orange2.png

[duck_arse]

an "equivalent IC" might end up being you matching a batch of p-channel fets.

are you sure it's the fet-pack that's the damaged party?

[czech-one-2]

Hi, no I'm really not sure what the problem is :-(
Its a nice old orange ROSS so I'dlove to hear what it sounds like! If theres anybody in the EU that wants to take a crack at fixing it I'll pay you for the repair! [Analogurru are you there?] 

[Mark Hammer]

The orange one is an interesting design.  You will note that the feedback path passes through a 5th phase-shift stage, except that stage is the reverse of the other 4 stages.  (I forget which is lead and which is lag, but it's the opposite)  The 4 main stages providing increasing phase shift (up to 90 degrees per stage) as signal frequency increases (i.e., more phase shift for 1khz than for 300hz), with the  point of maximum phase shift moving around via the LFO.  The 5th stage is fixed and provides more phase shift with decreasing frequency.

You will also note that, where most conventional 4-stagers will send the feedback signal to the 2nd phase shift stage (i.e., gets bumped back 3 stages from the output), this one send the feedback signal to the 1st stage.  In other words, with each recirculation, it passes through 5 stages - 4 variable and 1 fixed - as if it were a 6 stage phaser arranged the way a 4-stager normally is.

That makes it a rather different beast.

My guess is that a AM97C11 chip is sitting in somebody's parts bin somewhere in the world, but you're never going to find them.

[Nocaster Cat]

For what it's worth, I've never found any and I spent a good 18 months looking for them. I thought I had a lead for awhile...some guy swearing he had several dozen NOS but when it came time to actually complete the transaction, he hemmed and hawed and eventually dropped off the face of the planet.

[Rob Strand]

It's easier just to buy off the shelf JFETs and match them.  If you really want, start with JFETs close to the AM97C11 characteristics.