Not really. It wasn't clear to me whether you meant transistors, resistors, capacitors and so on or op-amps. When a discrete circuit has to consist of discrete op-amps, you lose most of the technical advantages.
Not in my opinion; what matters for DIY audio is whether it is more or less fun to design and/or make. Most discussions on this forum are about imperfections that are way too small to be audible anyway.
Why abandon anything?
What about your Firdac. Aren’t most posting about how to improve sound perception ?
But let’s agree that we most likely look in different ways at things.
Hans
Have you seen any solid evidence whatsoever that any of those changes did improve sound perception? I haven't, but if others believe that their sound has improved, I'm happy for them anyway. Besides, some of Mark's reservations about small-scale double-blind tests are perfectly valid, so it is practically impossible to prove that something is inaudible to everyone under all circumstances - which means that my remark about imperfections being much too small to be audible anyway should be regarded as an opinion that is not based on solid evidence either.
I predicted that this would become a repeat of the TIM wars of the 1980s, and I've only ever been wrong once, the time I thought I made a mistake.
Arf!
Chris
Arf!
Chris
See https://www.diyaudio.com/community/threads/opa1656-phono-preamp-split-from-opa1656-thread.377331
@PMA posted somewhere on this board scope photos of a super high-gain opamp receiving WiFi. These are anomalies made possible by excess gain and bandwidth.
@Chris Hornbeck - This thread is not about TIM but rather about using techniques other than high open-loop gain.
Ed
The receiving wifi is real. I've experienced it myself with AD797s, LT 1115 etc. But it has nothing to do with the open loop gain.
Where I've had issues it's been because poor phono sockets have been acting as receiving antennas.
FET input opamps are far less susceptible.
A suitable choke, or ferrite bead solves the problem.
Where I've had issues it's been because poor phono sockets have been acting as receiving antennas.
FET input opamps are far less susceptible.
A suitable choke, or ferrite bead solves the problem.
I'm not saying that there isn't a valid argument to intrinsic linearity. An amplifier made with type 12AX7/ECC83 vacuum valves (almost perfectly linear if applied correctly) is only a step of imagination away. Even DC coupling is possible, see GA Philbrick.
But this was thrashed out in about 1980 in magazine articles by John Curl and Bob Cordell, before the internet so sometimes forgotten.
All good fortune,
Chris
But this was thrashed out in about 1980 in magazine articles by John Curl and Bob Cordell, before the internet so sometimes forgotten.
All good fortune,
Chris
So, there is no actual evidence for such non linear behavior in modern opamps with feedback applied...
No. It just illustrates the rectification effect on RFI.
It has nothing to do with the open loop gain, but all to do with the excitation and the nature of the input stage.
It has nothing to do with the open loop gain, but all to do with the excitation and the nature of the input stage.
Including the one on power supply incursion?
Also, at audio frequencies we usually assume feedback acts without propagation delay. What about at much, much higher frequencies when demodulation and remodulation with audio signals may be occuring?
So, design the power supply to the opamps for EMI.
It's not inconceivable to design high open loop gain opamp based MC RIAA stages that lack these pathologies.
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Hello Ed,
a concrete circuit example, i.e. a schematic with dimensioned components, would illustrate your thesis very well.
Regardless of whether the tomatoes are thrown out of the audience or not, I'll take half of it. It's not about unqualified criticism or polemics, but about a pertinent discussion and analysis.
Perhaps you will present your RIAA EQ, a circuit that you may have designed 40 years ago. The intention of this thread originally comes from a current RIAA design by McdG. This design reminds me of the famous DUAL EQ from the early 1970s, so it's much older in origin - today it's old wine in new bottles.
so esoteric - but we are experts, so we can discuss it objectively and controversially.
kindly,
HBt.
a concrete circuit example, i.e. a schematic with dimensioned components, would illustrate your thesis very well.
Regardless of whether the tomatoes are thrown out of the audience or not, I'll take half of it. It's not about unqualified criticism or polemics, but about a pertinent discussion and analysis.
Perhaps you will present your RIAA EQ, a circuit that you may have designed 40 years ago. The intention of this thread originally comes from a current RIAA design by McdG. This design reminds me of the famous DUAL EQ from the early 1970s, so it's much older in origin - today it's old wine in new bottles.
Snake oil
so esoteric - but we are experts, so we can discuss it objectively and controversially.
kindly,
HBt.
OPamps have very high OLGain.
Which leads to need for compensation to ensure stability.
Amplifiers way back did not have so high gain.
Sometimes was not need for compensation.
I am with you @EdGr
But using opamps with some compensation result in very low THD.
Like @PMA has shown us.
How low THD do we need? I think lowest THD is not needed.
@Nelson Pass design amplifiers one after the other with some THD.
He believes the sound is good enough or even better.
Which leads to need for compensation to ensure stability.
Amplifiers way back did not have so high gain.
Sometimes was not need for compensation.
I am with you @EdGr
But using opamps with some compensation result in very low THD.
Like @PMA has shown us.
How low THD do we need? I think lowest THD is not needed.
@Nelson Pass design amplifiers one after the other with some THD.
He believes the sound is good enough or even better.