Re: Ahhhhh!! - MBK - Tweakers' Asylum

Re: Ahhhhh!!

Posted by MBK (A) on March 13, 2002 at 10:20:16

In Reply to: Re: Ahhhhh!! posted by Elso Kwak on March 13, 2002 at 09:46:24:

Hi Elso,

you mean fully balanced, i.e. using two D/A's per channel then? What I had in mind was simpler, splitting Iout into (+) - GND - (-) using 2 identical resistors, and feeding an instrumentation topology output i/v converter to unbalance. Idea was to get rid of the signal overshoot. That may be a similar fallacy though as the one you were describing, because the op amp may have symmetrically opposed overshoot that would not cancel out but just add upon unbalancing.

Incidentally I was looking around and found Wadia used OPA627's in a standard configuration, now they are using a current mirror type of chip (don't know - yet - what that means or would achieve). Wadia incidentally mentions that they liked the sound better by a measured injection of analog noise until it masks the digital noise, because analog noise seems more pleasant, ha ha.

Back to the "balanced" theme, there are complete solution chips for exactly that range of i/v conversion, for instance BB RCV420. That one seems made for this application and implements exactly what I had in mind on one chip. BUT the slew rate, bandwith and especially the noise figures are very bad compared to the usual op amp suspects. Limited bandwith in itself would be one thing we would want but the rest doesn't look so appealing. One could easily implement the topology with premium grade op amps though.

And yet another way could be to balance the output with 2 resistors and use a microphone preamp off the shelf. Hmmm. Maybe I just build a couple of these different circuits and try them all.

Balanced filters: that looks very smart indeed. But how do you get the filters to be truly symmetrical given usual capacitor tolerances? Because if they're not it's not a common mode error so the balancing won't help... or..? Can you give me the Crystal reference for that topology? - Thanks!

MBK

rcv420 (Open in New Window)

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Follow Ups Full Thread

Topic - TDA1541A sin(x)/x, I/V ... do I get this right - MBK 09:47:02 03/08/02 (19)

Re: TDA1541A sin(x)/x, I/V ... do I get this right - Elso Kwak 14:24:40 03/08/02 (17)

Ahhhhh!! - MBK 23:10:56 03/08/02 (11)

Re: Ahhhhh!! - Elso Kwak 03:35:28 03/12/02 (9)

Re: Ahhhhh!! - MBK 07:11:10 03/12/02 (8)

Re: Ahhhhh!! - Elso Kwak 00:20:14 03/13/02 (7)

Re: Ahhhhh!! - MBK 00:52:37 03/13/02 (6)

Re: Ahhhhh!! - Elso Kwak 09:46:24 03/13/02 (5)

Re: Ahhhhh!! - MBK 10:20:16 03/13/02 (4)

Re: Ahhhhh!! - Elso Kwak 12:29:28 03/13/02 (3)

changed to resistor i/v now... - MBK 09:23:52 03/14/02 (0)

Re: Ahhhhh!! - MBK 02:06:17 03/14/02 (1)

Re: Ahhhhh!! - Elso Kwak 13:18:07 03/15/02 (0)

Re: Ahhhhh!! - Thorsten 04:47:22 03/09/02 (0)

Re: TDA1541A sin(x)/x, I/V ... do I get this right - Thorsten 15:28:55 03/08/02 (4)

Re: TDA1541A sin(x)/x, I/V ... do I get this right - steve jones 11:06:50 03/09/02 (1)

Re: TDA1541A sin(x)/x, I/V ... do I get this right - Thorsten 15:57:00 03/09/02 (0)

Re: TDA1541A sin(x)/x, I/V ... do I get this right - JRR 20:20:14 03/08/02 (1)

Re: TDA1541A sin(x)/x, I/V ... do I get this right - Thorsten 04:38:28 03/09/02 (0)

Re: TDA1541A sin(x)/x, I/V ... do I get this right - Thorsten 11:09:31 03/08/02 (0)

Follow Ups

Re: Ahhhhh!! - MBK 10:20:16 03/13/02 (4)

Re: Ahhhhh!! - Elso Kwak 12:29:28 03/13/02 (3)

changed to resistor i/v now... - MBK 09:23:52 03/14/02 (0)

Re: Ahhhhh!! - MBK 02:06:17 03/14/02 (1)

Re: Ahhhhh!! - Elso Kwak 13:18:07 03/15/02 (0)

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