What Scott means DVV, is that Harris first developed the overall topology for the AD897, back in the 70's. Scott used it to best advantage, however, AND he then added his own patented modification that improves the measured distortion significantly. I am sensitive to this historically, because I normally develop topologies myself and I pay attention to their source.
Seen as you are experienced in the art, have you found starquad to help at all. Was thinking of using it when I go balanced because its ridiculous overkill in a domestic environment but only another 50p a meter.
If you search TI site for EMIRR, you will find that some opamps do have that specs, like those attached.
Sorry I do not follow this thread too much - wasting of time.
I pay about $65.00 per thousand feet for typical shielded pair. Starquads advantage is avoiding dimmer noise pickup. I tend to not have that issue by using a bit of distance. If there is an issue larger diameter cable also works. By this I don't mean the increase in wire gauge but a large shield diameter from either fillers or more insulation.
Then there was the fellow who specified data cable because of lower capacitance. He was quite surprised when at long lengths (1500') that the frequency response was all screwed up. Just didn't under stand the bit about constant impedance construction.
And how does the AD797 differ from a 741? They both have eight legs.
My experience is that when there is EMI that the noise floor appears to go up. This is from stadium experience listening by ear and confirming with an oscilloscope. The fix is to use metallic conduit, twisted pair cables, actual chokes, magic beads (haven't really had much luck with these or their varients) but the best result is to use is the AC power line filters that are two coils with slightly fancy magnetics. Very low power ones for microphone lines and bigger ones for loudspeaker level.
It is very common for hanging choir microphones to pick up radio signals. The bifilar chokes really do fix this.
Of course, this all relates directly to the opamp, and nothing at all to do with the rest of the system . . .
When factor in the Fourier components and the Fletcher Munson curves light dimmers perceived noise peaks around 3,000 hertz.
I have measured a lamp dimmer affect on the ac line via coupled network analyzer and the dimmer injected noise goes far beyond audio frequencies. Well into HF and RF and something an amplifier could try to amplify if the amps response went as high as the unwanted freqs. [no F-M curve for the amplifier]
THx-RNMarsh
THx-RNMarsh
well my question was admittedly based in lazyness due to having someone here whose probably had more hum problems than I've had hot dinners. I personally feel that its a no brained to have balanced interconnects even in benign environments as its cheap insurance, but have never looked at that tricky bit between 20KHz and when the RF decoupling cuts in.
You can see why galvanic isolation is liked in hostile environments!
You can see why galvanic isolation is liked in hostile environments!
Also in the Sound Technology's (model 1700) until the 5534 became available (model 1701). JC and SW have mentioned converting these old parties' front ends to AD797's, and I'll convert mine if I live long enough.
Thanks, as always,
Chris
But if you mention the T-word (input transformer) in polite company, you'll be able to hear your own heartbeat. Style rules everything - no exceptions.
All good fortune,
Chris
So the likes of SY are not polite? Guess he wouldn't argue with that! I like transformers and would use them if good ones weren't so spendy.
EDIT: for those not in the know http://syclotron.com/?p=145 SY really likes transformers.
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