Source for AD op amps?

[Ant]

I'm after some AD843's and really would prefer to get them from the UK.

Any suppliers?

 

[hifikrazy]

Tried RS and Farnell? Could always get AD to send you some samples

 

[penance]

RS have three flavours -

834JN stock no. 2508583632

834KN stock no. 2508584590

834AQ stock no. 2508133798

 

[Ant]

Thank yoouuuuuu

 

[Uncle Bob]

Curious... are you building a headphone amp by any chance?

 

[Ant]

Yes

 

[Uncle Bob]

I thought that might be the case - I've been thinking about building one to go with my recently acquired Grado SR225's and the question of which opamp to use has been occupying my 'daydream' time for a little while now.

Actually, RS are showing these as "Extended range items" so they're not available from stock and may be subject to extra shipping/handling charges.

Farnell don't stock them in the UK but you canorder from their US sister company Newark via Farnell for an extra 12.95 s&h on a 3 day delivery.

Digikey will also ship to the UK but I haven't checked if they stock the AD843

Which amp design are you building?

 

[Ant]

I'm thinking about using burr browns instead now.

I just came up with a very simple design myself starting with the straightforward chip and two resistors. Adding a bias current to take it into class A then running into a buffer due to the low impedance of the grado phones.

I'll draw a schematic once it's built as there will definitely be some changes.

Once I'm happy I'll be trying to get it all done with surface mounts to try and keep the signal path short.

The designs I've seen on the web (cmoy variants) look fairly straightforward.

 

[Uncle Bob]

I've been thinking about building a PIMETA - the design isvery similar towhat you describe - i.e classA bias with opamps driving buffered outputs. You'veprobably seen it already but the details are here

http://tangentsoft.net/audio/pimeta/

lots of good info on that site, the schematics and pcb artwork are available if you have facilities for making your own boards or they're available for $7.50 each.

The (pimeta) parts are mostly available here (farnell and RS) except for the class-A bias transistors but they're only $1.50 for a set.

 

[Ant]

I'd not seen that, I like the idea for the buffer, although I'll still do it my way I think

Actually for the Bias circuit can't you just use any jfet's in there? there must be something available.

 

[Uncle Bob]

You'll have to start a blog :dude:

let everyone know how you're getting on

 

[Ant]

Or keep it all to my self and start selling them

I think I could probably strike a happy medium