Maggin'

I have been playing with cartridges lately and one of the central points to any cartridge is the magnet.  I built this charging coil to re-magnetize the alnico magnet in a denon 103.

For s sense of scale here it is in relation to a charge coil for the magnet in a Sequerra ribbon.

This is a piece of more contemporary audio history.  JC built the charger for Dick Sequerra to charge the magnets for his ribbon drivers.

 The charger uses an ignitron (yes I insist on mercury even in my cartridges) to dump up to 14,000µf @ 600V into the charge coil.

While running it through its paces I was able to reverse the field in a N52 Neo magnet and in my attempt to see if I was reaching maximum charge this happened when I set the voltage to 400V and got a larger "POP" then expected.

The coil was 10 turns of #16 wire encased in JB weld.  The wire broke into several parts and the JB weld was nowhere to be found.   I have always heard stories how they would often vaporize the charge coil in big magnets.... never thought I would experience it first hand.

R.I.P. Art

It has been two months since Art left us and Janet reached out to me to help re-home the Step-Up that he was rotating through his system with his Denon 103.  This is the exact copper 1:15 H that he reviewed in Listening #176.   He preferred the sound of this copper unit compared to the identical silver version.  It has a 1:15 step-up ratio and is suited for cartridges with internal impedances from 20Ω to 50Ω.  The price at the time of review was $2400 and $1800 seems fair.  Payment will go to Janet Dudley directly and the SUT will ship from me with full support.  Physically this unit has been around the block so to speak but the function and sound is 101%.  Current pricing for this version in copper is $2700.  Pop me an email to discuss if this is a suitable fit for your system and by all means spread the word.  (SOLD)

a final reminder of Art's appreciation of the finer / furrier things in life

Doc Hoyer

Audio lost another of its treasures last week when Dennis R. Hoyer passed away in Milwaukee.  If you had a vintage transformer that needed help, Doc was the person to call.  On a recent trip to Milwaukee where I grew up I had the chance to visit his lab as 60+ years of his work was being dismantled.  As I was admiring his winder his cousin Damian put his license plate from 1980 in my hand and suddenly I got all choked up and truly knew who Dennis was.  


His files are a Who's Who of tube audio history

His winder was CNC controlled and built by him

I can't imagine driving around Milwaukee as a teenager seeing that bright yellow TESLA on the back of a Ford station wagon and not realizing I was behind someone truly ahead of his time.

SUT Writeup.

I figured it was time to jot down some ideas on how step-up transformers are best applied to MC cartridges.  Hopefully the info at the link is easy to digest and not too much of a veiled ad.

Moving Coil Step-Up Transformer Design Considerations.

as a teaser here is the venerable peerless 4722 compared to a SUT that follows the practices I have laid out.  Please leave comments with any critiques.

New Stuff.

Sheltering at home has lead to a few new things in the intact arsenal.  First is a low ratio Speakerformer.  These units offer 1dB-6dB of attenuation in 1dB steps and the shunt resistor is changed with each setting to keep the impedance the crossover sees a constant 8Ω or 16Ω.  These will handle 20W of input and are designed for crossover frequencies of 100hz and above.

Next is something that fits in the middle ground between the Elmaformer and the basic autoformer modules.  Many customers have been asking for an alternative to the plastic shaft found on the entry level units without the cost of the Elma switched version. These are based on a 23 position Blore Edwards switch and offer a good compromise between cost and performance.

It should be noted that all of the autoformers are wound identically to each other and the only difference between the various versions are in switch type.

From the Archives

The archives in this case being a dust covered cardboard box on a bottom shelf in the far corner of the 'Lab'.

The chassis work by Melissa & Doug represents the 'Early Davey Functionalist' era that predates the 'Drug thru the Hudson' look of the early 21st century.

It is a simple remote controlled 100K linear pot attached to some RCA plugs used explore loading options for MC cartridges.  At one point the concept piqued the interest of a well known Stereophile reviewer but upon borrowing the unit, he was terrified to plug it in to his system so into the archives it went.

The remote controlled pot was the handy work of of our good friend John Chapman and the concept evolved into the Opti-Load which replaces the pot with a relay controlled resistor matrix.

ERC in the NY Times

We love to see it when friends get the credit they deserve!  The NY Times did this nice piece on what Pete Hutchison is doing in London with his Electric Recording Co.

Pete also owns peace frog records for a slightly more contemporary vibe.