Strain Gauge

Jack @ the audio Beatnik just put up some kind words about the strain gauge.

https://theaudiobeatnik.com/emia-strain-gauge-cartridge-with-equalizer-phono-preamp-review/

In it he made note that Sao Win invented the strain gauge and some day I'll put the whole history as I understand it in a future post but for now the earliest example I have found is from 1946 and it also qualifies as possibly the most beautiful cartridge ever.

This is from the "Fabulous Capehart" which also had a Brook PP 2A3 amp and a Western Electric 728B so this beauty hung around with the right crowd.

CAF 2018

Another year... another awesome event.  We took the show on the road again down to Washington DC for the Capital Audiofest.  This year consisted of a stack of rebuilt ESL 57 panels in a "stacked T" configuration.

Each pair of stacked panels had its own 300B based biamp setup with a line level crossover and step up output transformers.

The big changes in the amplification for this year were the addition of mercury rectifiers and .9999 silver wire throughout the amps including the plate chokes and output transformers.

The front end was analog only sporting a couple of 301's in maple and dymondwood plinths.

The cartridge was the next revision of the field coil built from the ground up seen here spinning on a test pressing of an upcoming ERC release of The Folk Blues of John Lee Hooker.

More of the ERC collection was also available to play.

Rather than go on about how awesome the sound was, we will leave it in the capable hands of Art Dudley and Michael Lovorgna

https://www.stereophile.com/content/rocking-rockville-late-day-one-and-early-day-two

https://twitteringmachines.com/caf-2018-emia-labs/

we will add more links as they come in.

ERC

Had the chance to pay a visit to Pete Huchison at The Electric Recording Company and here are some of the visual highlights of the trip.

The centerpiece is of course the Lyrec Cutting Lathe.

Also on site were Neuman and Scully

Other things of note were the EMT930 and the Westrex cutting amps

 Of course there was a selection of their work on display

and this necessity of any studio

which is of course a place to store the cut lacquers.

On the listening side it was really cool to hear the comparison between an acetate and the test pressings of upcoming Bill Evans and John Lee Hooker releases.

Forevertron II

I get to cross another thing off my bucket list and that is a visit to Dr. Evermore's Forevertron Sculpture park.

OK you must be asking what does an Altec 1803 have to do with art?

and if you look a bit closer this odd bird has a 288 up its bum.

 Audio folk can rest assured they come from the stereo era but tend to have channel separation of 100 feet or more.

The above birds come from the Altec genus and the more pedestrian brass genus was also well represented.

Finally the ultra-rare unobtanium WE genus also makes an appearance.

alas.... unlike the lowly Altec's, the WE sample is sans 555

LR Phono - with official seal of approval

so we have been working like mad on this:

and listening to a gazillion subtle changes... 

like 49% versus 80% nickel cores in the 

outputs... guess which one sounded better?  

and then when grabbing the output tubes we 

noticed something on the bottom...

yep... so the new LR Phono is officially ready.... 

seal of approval and all... 

and this is happening in the Hudson Valley... just bonkers!

peace,
me

Tannoy Redux

A decade or so ago, I played with some nickel cored versions of the Tannoy crossover parts for Arthur Loesch.  Recently, Chris from Jupiter Condenser had me do a complete set using his 0.99999 pure cotton served copper wire.

The cotton serving takes up a fair bit of the winding space compared to typical magnet wire insulation so some creative license was needed to keep the parameters identical to the original.  Luckily, the higher perm of the 80% nickel cores made this easy!

In the original design the ~0.5mhy inductor was air cored and had a rather high DCR and was in series with a ~4Ω resistor and I needed to juggle the DCR and and resistor values to net the same end result.

Since the theme here was 80% nickel, it only seemed appropriate to use that to my advantage for the above choke and sneak a few lams into the typically air cored inductor above to keep the family character.

LCR Tape EQ

Just finished up a LCR tape EQ for a customer in Hong Kong.

Single ended input and output with 40dB of gain and three different EQ filter options. (NAB, 7.5ips IEC and 15ips IEC)  This follows the basic topology of our phono with permalloy output transformers and power supply chokes.

In this instance the customer needed a balanced input so I built an active Balanced to SE gain stage based on a pair of 2SK170's loaded with an 80% nickel transformer that brings the overall tape gain up to 60dB.