Balanced Phono Cables, and Preamp update

[GeorgeP]

As an Electronics Engineer I designed a new distortion less Preamp with Ambience rear channels... similar to the Phase Linear 2000, but much much better.
The overall design is 99% complete. Offered as a kit, also semi kit with tested PCBs, and also complete built and tested. That is posted elsewhere on this site.
The front panel and real panel are designed and look beautiful. Attached below. I'm added an array of XLR balanced inputs and outputs for best noise immunity. Those PCBs have just been ordered.
I also just designed a Balanced XLR output driver with a perfect RIAA Curve. Now you can put the turntable up to almost any length of XLR cable at Line level to a preamp with XLR inputs, or...use the XLR balanced Line receiver I also designed for this... changes it back to un-balanced RCA Jacks at the preamp if you don't have XLR connectors on the preamp. When this effort is done, I will release everything as kits with options as you want.
I work full time at Brookhaven National Laboratory and work on this project outside the job... Its a labor of love!

 

[mlucitt]

George, what is the sensitivity of the Phono input in your preamplifier?

 

[GeorgeP]

George, what is the sensitivity of the Phono input in your preamplifier?

I will verify again on the 2nd prototype... I used .004V (4 millivolts) to measure the 10V RMS at line output. I used a flat DC resistive 40 dB attenuator from a line level source generator at 1KHz. 68 dB gain or so just at clipping to make that measurement. I forget what cartridge I have in the AR Table... Installed 40 years ago! I'll look later and let you know. I am easily able to turn the volume up past clipping. when I pick up the tone arm...its dead quiet. I rewired the tone arm with really great cables, and it has a separate ground wire not tied to the shield... Look at the chip specs, its really amazing I thought. Texas Instruments OPA1602 (35MHz @ $3 bucks each). I also tried the OPA1612 (40 MHz & more expensive @ $7..68 each), (and tried the OPA1662 (22MHz @ $ 1.98 each.) All three performed the exact same way, so... no need for the super wide bandwidth. above 22 MHz. I'm using the 1602s, the 1612s are much more expensive and really overkill. I measured and heard NO difference. All stages use the same chip part number. I may consider the 1.1 nV 1612 for the 1st phono stage only if there is even the slightest measurable increase in the noise floor. So as I can see or hear, there is no real justification for the more expensive chips, but it is an easy option to consider. All same footprint! 1st sheet of each type attached below. Have a look.