The "BEAST" All Tube MM/MC Phono Amplifier

The "Beast" by Aural Thrills Audio

All tube MM/MC Phono Amp

Please see glowing review in "The Absolute Sound Magazine by Dick Olsher, senior editor"

I have called this the beast because it must be the biggest phono stage out  there. It uses old school methods for voltage and current regulation as well  as rectification. Carbon composition resistors in the power supply give it that 50's style richness, but still with great detail. I used a 274b rectifier tube because they sound like no other. The sound stage is gigantic with pin point placements of all the instruments. The tubes are very large, old school style, so I had to  find a way to fit them into the chassis. The chassis is available in two sizes. 177mm high which will fit a 5U4GB or 220mm high which will fit any 274b.The result of all of this work is the real sound of the tube era but with modern detail. Unlike most amplifiers that claim to be all  tube, this one really is. It is not a solid state unit with a tube buffer on  the output to make it sound tube like. It is not a pumped up Mosfet front end so that you can use a LOMC. It is ALL tube! (OK, I know the 12ax7 power supply has SS voltage regulation.) Super quiet is also necessary so a  special gas voltage regulating tube is used in the power supply. Indeed this  is old school.

The power board includes super audiophile parts such as Takman Carbon film, Audiophile resistors, Mundorf Evo Gold oil filled capacitors, Polystyrene capacitors for the RIAA filter. Nichicon  Audio Grade electrolytic capacitors, high end  red Copper Rca connectors, and a R-Core transformer. The best of everything.  The result is a sound that will bring tears to your eyes. It is old school  done right with only the best components. 

No need for a step up transformer. They can not compare to an all tube unit.  A step up transformer increases voltage at the expense of a decrease in  current. The sound is wimpy compared to this. 

The dip switches control three aspects of the amps operation. With them you may need to make additional adjustments for individual cartridges.  First is the AC Impedance. The resistors are set at #1, 2.7K ohms. #2, 1.3K ohms, #3 510 ohms, #4 is 200 ohms. I suggest that you use this as a tone control. #1  is + Treble and #4 is + Bass. You can also use the Dip switches to adjust the amount of input signal which is sent to ground. This is useful in matching the output of the pre amp to your power amplifier. .

You will not find a comparable unit at any price to listen to your priceless  vinyl. This is the way records were meant to be played. After listening to  this unit you will understand why tubes are still so popular. You will  understand why tubes and Vinyl are a match made in Heaven.

Standard Tubes included:       Optional NOS Tube Sets Available at extra cost when available.

5 X 12ax7, 2 X 6V6GT, 1 X 274B/5u4, 1 OB2 Gas Tube

ABOUT THE DESIGN

I have been working on this same phono amp for over ten years now. I built this amp because I was not happy with the sound of a step up transformer. It colored things too much. From hard wired to fully regulated I have designed this amp by ear. I know what each circuit adds to the sound. I know what each part sounds like. I studied music at a college that made Zoltan Kodaly ear training mandatory. You learned how to listen by being locked in a closet size room with a piano listening to chords, scales, modes, all the different sounds. You were also taught tonal memory and the ability to listen to music and transcribe it directly onto paper. A test would include such things as identifying chord qualities when played on a piano, singing  notes twenty minutes after hearing them, notating songs as they were played on a piano. This was the hardest course that I ever took. The result of all this is the ability to hear every part of my amplifier's sound and be able to identify it. I have meticulously listened to different resistors, capacitors, wire, etc. to come up with the perfect "you are there" kind of sound.

 


 

Tubes included:

5 X 12ax7, 2 X 6V6GT, 1 X 5U4GB, 1 OB2 Gas Tube

  MC MM   Vacuum Tube Complement 4 x 12Ax7 3 x 12AX7 Inputs 1 pair single-ended RCA 1 pair single-ended RCA Outputs 1 pair single-ended RCA Gain (Total 62dB) 60 dB 50dB Output Impedance 425Ω Frequency Response +0 -1 dB 10Hz – 50kHz Maximum Output Voltage <1% THD 20V Cartridge load impedance Variable: 100Ω, 500Ω, 470Ω, 1.2k 1.8k 47kΩ, Minimum Recommended Cartridge Output 0.2 mV 1.5 mV Signal to Noise Ratio 50 dB 56 dB Channel Separation > 50dB (20 Hz – 20 kHz) Power Consumption 20W Dimensions W x D x H 21x 20x 8″ Weight 27 lbs  packed