Dear @ejb 14 and friends: From where comes " stupidity ", normally from ignorance/low knowledge levels and skills.
Between 20+ years from today we made our first intent to design and build a phonolinepreamp due that what been in the market were not satisfied not only my LP reproduction demans in quality overall performance levels. My audio items that were my references in those times were units from FM Acoustics, Gryphon, ML Reference and the like.
So we started with a battery powered design with a single layer boards and using op-amps in two different ways.
We used these ones:https://datasheetspdf.com/pdf-file/919966/NationalSemiconductor/LM607/1
( in the plastic not metal package ) and this one:https://www.ti.com/lit/ds/sbos058a/sbos058a.pdf?ts=1602967034703&ref_url=https%253A%252F%252Fwww...
and the opa 2604 too.https://datasheetspdf.com/pdf/475618/Burr-Brown/OPA2604/1
passive inverse RIAA eq. using teflon caps and Caddock resistors.
I still have this unit and ( believe or not. ) performs really great with no regrets/compliants about and even today can compete with some good " names " units.
After this successfully intent ( because we had to know first if our design could works and it did it ! ! ) we put on paper the targets for a more definitive phonolinepreamp that not only worked but that could outperforms the best of the best phonolinepreamps in the market and that fulufill all the cartridge needs of any cartridge and from here born the Essential 3150 followed by the 3160 and my today unit 3180.
My first phonolinepreamp targets I still have and were writed in plain paper by hand/pen and is dated: 26-11-96 ! !
several of the original targets can't be ( yet ) achieved and some of them are almost " crazy " and for other gentlemans/designers maybe utopic ones.
Anyway here some of the acomplished targets:
The Essential 3160 is an active high gain/low noise fully discrete design that use bipolar transistors in two gain stages for MC phono stage and FETs for MM phono stage.
In reality this phonolinepreamp have three preamps instead of only one: it has a MC phono stage, it has a MM phono stage and a line level stage preamp. All this three stages are totally independent from each other.
Each phono stage ( MC and MM. ) is designed for its self precise and specific needs.
Our design is a discrete Non-feedback, direct coupled, pure class A , current mode, true balanced ( differential ) input to output, dual mono design and fully regulated input to output.
The dual mono design only share the chasis but both channels are totally independent from each other even in the dual mono external power supply ( that use too a pure silver Kimber Kable power cord. ) that is so important to the performance on this phonolinepreamp, it has separate attenuator volume control ( that been an attenuator design that when is attenuating the SPL at the same time is lowering/attenuating the noise levels. We work with the input signal 100% SPL, no attenuation at all. ) and separate phono/line switch, impedance changes by solder resistors.
Inside parts: teflon Cu capacitors, " naked " Vishay resistors,matched transistors , hand selected parts, no internal wires ( every part, including input/output RCA/XLR connectors, are soldered directly to the four layers circuit boards. ), etc....., only the best neutral non-sound parts ( no step-up transformers, no head amps, etc.. ) and in the critical stages with tolerances at 0.001%. All parts working at no more of its 50% efficiency. A unit impossible to overload it.
A developed proprietary technique guarantee an accurate RIAA de-emphasis accuracy of +/- 0.011 dB from 20 Hz to 20 kHz ( Both channels ), resulting in a neutral phono stage that reproduces exactly what the cartridge generates that are in the recording.
The result is a preamplifier combining the purity and transparency of a passive preamplifier with the speed, dynamics and drive of an active preamplifier ( Truer to the recording. )
To round off the preamplifier's RIAA capabilities, its has a switchable 3.18 us turnover point Neumann pole. ) to compensate for the cutting head preemphasis HF roll-off during the recording.
The op-amps that mentioned that gentleman were used not to amplify the cartridge signal in no single way, this signal is touched only by passive/active discrete parts. The output buffer is a metal encapsulated fully discrete design that looks as an op-amp but certainly it's not.
Due that my ML 20.6 monoblocks use in the signal input gain stages these metal encapsulated fully discrete devices ( that looks too as an op-amp ):https://www.analog.com/media/en/technical-documentation/obsolete-data-sheets/MAT02.pdfhttps://www.analog.com/media/en/technical-documentation/data-sheets/MAT03.pdf
we were thinking to use it because it has a first rate design but at the end we decided to make our own fully discrete bipolar discrete high gain design that was and still is a fenomenal challenge for any electronics SS designer/manufacturer..
I know that that low knowledge level ( that was the only reason he asked on those op-amps. I think? ) gentleman would like to know more about our design but this is not possible to him or any one else..
You know we in 1996 was thinking/targetting in a current mode design that today is the fashion. Yes welike what we did it and not because we did it but because is well worth our effort: very high rewards.
Regards and enjoy the MUSIC NOT DISTORTIONS,