Month: March 2020

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Click this link to stream a special two-hour Preservation Sound Radio show focusing on: Psychedelic Soul. (show starts approx 12 minutes into the file). This show was assembled in my studio and relayed for broadcast on WPKN. Audio-nerd notes: the entire program was assembled from my vinyl LP collection, freshly transferred via a vintage Denon DL207 MC cartridge through a 1:20 ADC step-up transformer unit I assembled this week. My voice via a 1950s EV 666.

Tracklist:

1. curtis mayfield DO DOO WAP IS STRONG IN HERE
2. cymande BIRD
3. the main ingredient SUMMER BREEZE
4. brother to brother I WISH IT WOULD RAIN
5. minnie ripperton LES FLEUR (set break)
6. soul searchers WE THE PEOPLE
7. the temptations SMILING FACES SOMETIME
8. junior parker TOMORROW NEVER KNOWS
9. manu dibango HIBISCUS
10. the dramatics IN THE RAIN
11. shuggie otis JENNIE LEE (set break)
12. rotary connection PAPER CASTLE
13. rasputin’s stash YOU BETTER THINK
14. edwin starr BALL OF CONFUSION
15. sly and the family stone TIME
16. james brown JUST ENOUGH ROOM FOR STORAGE (set break)
17. the southside movement IVE BEEN WATCHING YOU
18. eugene mcdaniels CHERRY STONES
19. the sound experience EVERYTHING IS BEAUTIFUL
20. dennis coffey LONELY MOON CHILD
21. david axelrod FREEDOM (set break)
22. funkadelic ILL BET YOU

Above: prototype of a novel design for an economical all-tube headphone amplifier. I have been hunting for a way to build an all-tube cue amp into the @berlinettabrewing DJ console. I was forced to design this because no decent schematics exist anywhere online for something like this: something compact, simple, and inexpensive to make that can run either 600 ohm cans or modern low-impedance cans.

This design uses a basic voltage amp (1/2 a 12AX7, although a 12AT7 would work fine too) driving one paralleled cathode-follower 6CG7 per channel. In theory, with a big enough output cap and 300 plate volts, this SHOULD be able to drive 600 ohm headphones to a very high level. And it does. But here’s the twist: the “600 ohms” jack is a switching jack that, when blank, sends the signal to a pair of 600 ohm:8 ohm “70v” 5-watt line-to-voicecoil transformers: I used inexpensive old Stancors. These are the sort of transformers that you often find inside old schoolhouse baffle speakers.

At full rated level, the low end of these transformers is weak. But at the 1/2w that they see in this circuit, they sound absolutely fine. The amp sounds great with either variety of cans- i tried @akgaudio 600 ohm k240s and @audiotechnicausa ATHM50, which I suspect are 30 ohms-ish. Way way more then enough level, great fidelity and just great sound all around. A little experiment that paid off, coming soon to the world’s most esoteric DJ console.