GPulse-Linear Preamp update.

[GeorgeP]

Hi gents. I just packaged up the Rev-B boards into the new chassis and did some in depth testing.
I hope you all like the look.
You can build it as a kit, purchase the subassemblies as you like. Or...purchase built and tested boards, or the entire plug and play fully tested preamp. Send me a private message if you have any interest in this.
I just fine-tuned the RIAA PHONO Curve...extended response down to 3Hz. Phono preamp is DC coupled. Attached pic is the P-Spice simulation, compared to the original Phase Linear PL-2000. My version is exact match to within 0.2 dB total with more "punch" at 3 to 10Hz, below the 20Hz RIAA Spec for +20 dB. You will feel it!
Attached are some pics for you all to look at. It has the ambience rear channels and the separate tone and turnover frequency controls.
Personally...I love it❣

 

[GeorgeP]

Hi gents. I just packaged up the Rev-B boards into the new chassis and did some in depth testing.
I hope you all like the look.
You can build it as a kit, purchase the subassemblies as you like. Or...purchase built and tested boards, or the entire plug and play fully tested preamp. Send me a private message if you have any interest in this.
I just fine-tuned the RIAA PHONO Curve...extended response down to 3Hz. Phono preamp is DC coupled. Attached pic is the P-Spice simulation, compared to the original Phase Linear PL-2000. My version is exact match to within 0.2 dB total with more "punch" at 3 to 10Hz, below the 20Hz RIAA Spec for +20 dB. You will feel it!
Attached are some pics for you all to look at. It has the ambience rear channels and the separate tone and turnover frequency controls.
Personally...I love it❣View attachment 86212View attachment 86207View attachment 86209View attachment 86211

So today I connected my AR77XB turntable to my preamp, and Wow...sounds amazing.
I also made some max noise measurements on the phono stage (inputs horted).
Volume control at max, tone controls out, and low Freq EQ off. I have never witnessed a more quieter preamp. The sonic quality is measured as designed, and sounds awesome. The videos...to large to post here, I tried. If anyone wants to see them...email me at abekc@optonline net.

 

[GeorgeP]

Update on GPulse-Linear Preamp:
I was noticing the typical Rumble from the turntable (AR X7 belt drive manual) at high volume, and decided to tackle that as a special effort in the preamps design.
Well...I used PSpice modeling software and engineered a terrific discovery!
I was easily able to add a notch filter below 20Hz, without affecting the 20Hz to 20KHz RIAA Curve at all! Look at the attached pic. A 5Hz centered notch filter kills rumble, and the 20Hz punch is unaffected. I added an inductor to the exsisting time constant DC block capacitor making a parallel resonant high impedance circuit at the - terminal of the opamp. Perfect. I am getting the inductors next tuesday for the test. A special Toroid self shielded type. Does 20 dB attenuation at 5 Hz sound good? Should be not noticeable at all, except speaker flopping stops. Saves power also.Yup.