Sound Quality Vs. Measurements

[john curl]

Most potential objections? How about more than most, with a discrete comp fet output stage, self biasing, and with dist adj. if useful?

 

[SY]

Yes, those are solutions, but what's the problem you're trying to solve? Other than fashion and prejudices, of course.

 

[john curl]

Just lower open loop higher order distortion. It's kind of what I do for a living.

 

[SY]

Because 0.000x% at 80dB gain isn't good enough? Really?

 

[nigel pearson]

An op-amp with it's head in the clouds

I remembered this title and that the author claiming it had class A output .

The title did produced this .


Hickman's Analog and Rf Circuits - Ian Hickman - Google Books

Any ideas ? JFET if I remember and - 90 dB distortion .

 

[SY]

They make another chip, the 1570, which will take the output from a 1510/1512 and drive balanced lines.

My mistake, the driver chip is a 1646. The 1570 is another diff input amp with ridiculously low noise and distortion. Tough to beat (or even equal) with discrete.

 

[scott wurcer]

Because 0.000x% at 80dB gain isn't good enough? Really?

Careful on that, I think their implementation starts to have rising THD at 60 or 70dB of gain, not that it matters but it is no longer in the mud at 80dB. And that's that.

 

[scott wurcer]

Hot ding!

To be honest, I had never even heard of this company until a few minutes ago, here.

Some (some not) ex DBX guys, a great bunch serving a niche market with some good stuff.

 

[nigel pearson]

LM110

http://www.datasheetcatalog.org/datasheet/nationalsemiconductor/DS007761.PDF

This one is interesting . Long dead I fear .

 

[a.wayne]

So John is going to give an IC a twirl and Sy is doing boutique Hi-FI......



.

 

[nigel pearson]

OPA 604

This should stop that .

http://www.ti.com/lit/ds/symlink/opa604.pdf

 

[a.wayne]

Throw up an active filter with those puppies and they operate at 24 volt which is nooooice for dynamics .

@john ,

C'mon John give us a 3way active xover with the JC-3 , direct drive, impedance matching, all in one unit , phono pre separate ...

 

[john curl]

Not here, that is for sure.

 

[bcarso]

Actually if you make the pot 100K and R14 10K then the circuit makes sense. It gives better feel to the gain trim control. So I suspect this is really an argument about a typo.

Well fortunately it was easy to dig up the actual link (once it occurred to me to do so!) Low Noise Balanced Microphone Preamp

And --- no mention of the function of the 100k, but a description of the 10k as requiring a reverse log taper! And there is even a mention of the 1000uF cap: "There is usually no problem with zero DC bias on modern electros. "

I guess the main author, Phil Allison, figures some number of millivolts are close enough to zero, on the one hand. Of course on the other, what he's alluding to with the remark is the absence of a "forming" voltage.

There does seem to be a little confusion about noise figures. The statement is made that the preamp manages 0.9dB noise figure with a 200 ohm source, but that the equivalent input noise spectral density is 1.9nV/root Hz. This is probably neglecting I sub n, and in any case it would have to be 1.82nV/rt Hz to do 3dB, a good deal worse --- although most recording situations would have a higher ambient than the stated noise anyway.

 

[benb]

OMG, I remember Phil from sci.electronics.design (I haven't read or posted in Usenet much in recent years). Put on your asbestos (or other flameproof substance) suit before reading his posts.

I just peeked in, he's still posting and still a potty mouth.

 

[a.wayne]

Not here, that is for sure.

Never meant such .....

 

[dvv]

I think that we should add a discrete output stage to the 1510, and it would be even 'better'.

Exactly my thinking.

Use THAT for the input, add a discrete cascode above them and you should be home and dry. Using something like say 2N5551/2N5401, rated at 140 V, or some such, you should have no problems, but should cash in on thermal stability.

That's assuming you are willing to settle for bipolars rather than FETs.

And I think the price is very reasonable.

 

[dvv]

Some (some not) ex DBX guys, a great bunch serving a niche market with some good stuff.

Yes, I can see that, Scott. These people know their stuff, to be sure.

Subjectively, after years of having some good audio stuff discontinued, they are a breath of fresh air.

I may never get over the loss of 2SK170, thank God I have a small stock of them.

 

[dvv]

So John is going to give an IC a twirl and Sy is doing boutique Hi-FI......



.

And nobody is doubling down!

 

[dvv]

Yes, those are solutions, but what's the problem you're trying to solve? Other than fashion and prejudices, of course.

I think it's not about solving problems, it's more about avoiding them by design before they happen.

I lost count of the perfect ciruits, measuring next to perfect, which actually sounded so-so, or even downright poor.

So I learnt to think ahead, mostly in the direction of keeping as many of my options open as possible. I learnt it the hard way, by first not thinking ahead, and then having to slave over something that initially looked great, but turned out not to be so great. And vice versa. So it pays to think ahead.