The quietest audio op-amp with ultra-low THD

[Martin Griffith]

John Larkin wrote: snip

Do you know how much good audio transformers cost ! I like Lundahls but you get such a
little thing for so much money. Say $80 ea. The client has indicated btw that cost is a
major factor so it might be back to 5532/4s (good enough - the rest of the desk is stuffed
with them) and a discrete front end.

Check out that 2SA1083/4/5 btw. www.profusionplc.com has them in stock (they can be tricky
to get hold of) and a link to the data sheet.

Graham

Have you tried the zero Z transformer method?
Thats when you load the Tr with a VE, and have the mix R's on the
input side?
I've got Ted Fletchers VE cct somewhere, but never tried it

martin

 

[Eeyore]

Have you tried the zero Z transformer method?
Thats when you load the Tr with a VE, and have the mix R's on the
input side?
I've got Ted Fletchers VE cct somewhere, but never tried it

Transformers are not even remotely plausible for budget reasons. Why would you want one anyway
?

Graham

 

[Martin Griffith]

Transformers are not even remotely plausible for budget reasons. Why would you want one anyway
?

Graham

It was only an idea. Ted's cct uses a single opamp as a balanced mix (
no transformer, that was not really apparent in my previous post)

I had just spent the morning simulating modem/phone transformer in
virtual earth configs. Quite interesting (sort of), I got quite
reasonable results.

martin

 

[Eeyore]

?

It was only an idea. Ted's cct uses a single opamp as a balanced mix (
no transformer, that was not really apparent in my previous post)

Ah ! No balanced bus available here, although there is a 0V sense line.

Graham

 

[Martin Griffith]

Ah ! No balanced bus available here, although there is a 0V sense line.

Graham

Yep, you just loose 6dB signal level, but get exceptional cmrr that
way, with a diff amp, I'll try and find Ted's circuit if you are
interested.

martin

 

[Eeyore]

Yep, you just loose 6dB signal level, but get exceptional cmrr that
way, with a diff amp, I'll try and find Ted's circuit if you are
interested.

Well it's always interesting to take a peek.

Graham