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Maker Pro

The quietest audio op-amp with ultra-low THD

M

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
 
E

Eeyore

Martin said:
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
 
M

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
 
E

Eeyore

Martin said:
?

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
 
M

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
 
E

Eeyore

Martin said:
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
 
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