Phase shift itself when reactivity is driven does not create distortions; what does, non-linear output impedance of the thingy that drives.
Speaking of measurements, what may be observed, a phase angle between input and output signals. For better visibility the load may be plain resistive. And again, let me repeat myself: single-ended phase inter-modulation may be inaudible, when it mimics Doppler effect. Otherwise it sounds nasty. Long time ago I thought that it may be used for guitar effects. Nope! It sounds nasty when is non-linear and significant; I tried it with bass guitar thinking of aggressive sound. Gave up.
Speaking of measurements, what may be observed, a phase angle between input and output signals. For better visibility the load may be plain resistive. And again, let me repeat myself: single-ended phase inter-modulation may be inaudible, when it mimics Doppler effect. Otherwise it sounds nasty. Long time ago I thought that it may be used for guitar effects. Nope! It sounds nasty when is non-linear and significant; I tried it with bass guitar thinking of aggressive sound. Gave up.
KSTR said:
Problem is the AD846 obsolete and missed by some audio guys was a classic CF video op-amp fully cascoded and DC precisioned so that the OLG corner was 400Hz.
Pretty easy on the AD844 the pin is there to cripple the VAS for any OLBW you want. I talked with Mitch for almost an hour and he's not telling much. I still think this stuff is a red herring but I'm not going to argue about it anymore.
Yes, almost. But the AD844, e.g., is more than 10x faster, regarding SR, and it counts. OLG is quite same, but the AD844 is CFA, and it must be considered.
PMA said:
Also, the AD844 can be used open loop with excellent audio performance, howzzat for audio nirvana 😉
You can set the gain by the ratio of two resistors (to pin 2 and pin 5).
jd
Hmmm,
What would make a good video drop in replacment for a
TL0072CP ?
I've heard of some folks making a whole board that replaces
the op amp itself.
Wondering how much of an improvement it would make?
Funny thing, on a Joe Cursio tube dac that I have, a buddy of mine was
telling me to upgrade all the audio opamps with video op amps,
that the whole thing would better.
Problem is Joe scratched off all the nomenclature on his op amps
and offers upgrades though his web site.
I'm thinking the upgrades would be less expensive buying through
digikey or mouser, or someone else.
Sync
What would make a good video drop in replacment for a
TL0072CP ?
I've heard of some folks making a whole board that replaces
the op amp itself.
Wondering how much of an improvement it would make?
Funny thing, on a Joe Cursio tube dac that I have, a buddy of mine was
telling me to upgrade all the audio opamps with video op amps,
that the whole thing would better.
Problem is Joe scratched off all the nomenclature on his op amps
and offers upgrades though his web site.
I'm thinking the upgrades would be less expensive buying through
digikey or mouser, or someone else.
Sync
AD844 output stage is far from excellent, should be replaced by external high current buffer for OL audio nirvana
dimitri said:
Plain old diamond buffer. Thanks! for the FET's BTW (and socket). It's easier to use than the ones we stock.
Hi Scott,
Most of mine have been discrete, I haven't tried anything like BUF634 yet. I'm thinking that the parts should track much better in a thermal sense.
-Chris
That may well be, but there is plenty of life left in that design as far as I'm concerned. 😉
Most of mine have been discrete, I haven't tried anything like BUF634 yet. I'm thinking that the parts should track much better in a thermal sense.
-Chris
PMA said:
Yes Pavel, AD844 is an great opamp (I'm using it as well)...but it has one big flaw...it's out of production, so availability, even for diy purpose, in future is questionable.
dimitri said:
I'm using AD844 as I/V converter (open loop) + it's buffer...and it does sound pretty good as long as the load is light (TVC S&B TX102 MkIII in my case)
john curl said:
Well, I'm placing my bet too on AD825...as error opamp in hybrid super-shunt regulator. One question John...is that Plashe current mirror differential as a load for folded cascade in simplified AD825 schematic?
In an audio preamp
Why is super high bandwidth , OLG BW and SR more important than low 1/f voltage noise, distortion and DC accuracy?
What is the noise corner freq for a jfet input video amp?
The typical audio source is BW limited anyway so slew rate is not that important> how much gain end-end do we need.... Av=2? Some folks use an attenuator for a preamp.
Compare your video op-amp design to an OP37(OP27, Av<2) for an audio benchmark?
Why is super high bandwidth , OLG BW and SR more important than low 1/f voltage noise, distortion and DC accuracy?
What is the noise corner freq for a jfet input video amp?
The typical audio source is BW limited anyway so slew rate is not that important> how much gain end-end do we need.... Av=2? Some folks use an attenuator for a preamp.
Compare your video op-amp design to an OP37(OP27, Av<2) for an audio benchmark?
If you go back a few thousand posts you start to get the ideas here. Simply put the traditional measurements don't indicate audio quality which is the reason for this. If they did then we wouldn't be exploring these ideas. If you are happy with traditional solutions its hard to beat a mid '80s Japanese integrated amp. No distortion, perfect RIAA and flawless performance (and to many unpleasant sound).
1audio said:
haha\ Jap integrated amp
OK I'm all for new stuff, but I still think my Q shouldn't be dismissed by simplification/comparing to mid 80's designs. BTW I think the primary reasons for "unpleasant sounds" are due to those haphazard class AB poweramps and mostly the evil Sanyo solutions.
Are there any technical goals or defined new topology for a preamp?
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