Friday, May 4, 2018


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.

Wednesday, April 4, 2018

Tarragona Audio

Pictured below are 14 pieces of lovingly hand crafted nickel for an all out design of a microphone preamp by our good friend Peter in Berlin.

This device is unique because unlike the typical professional "buffer it all and let god find the music" approach of some, Peter harkens back to the days of yore when transformers and inductors were the proper tools to use and what something sounded like actually mattered.

The 14 permalloy pieces consist of 4 - DC carrying output transformers that load active devices, 2 - level control autoformers, 2 - tapped filter chokes, 4 - nickel power supply chokes, an input transformer and a phantom power choke.  No caps exist outside the power supply and at the next ETF I will lobby for some filament supplies.  As it stand, i think it is awesome and if given the choice between using transformer loaded Fet's and chokes or tubes and caps I think peter made a wise choice.

full details of this design can be found at Tarragona Audio

Friday, February 16, 2018

GM70, Silver and Nanocrystalline

Just finished these up for a GM70 amp Jeffrey is building for a customer.  They are wound with 0.9999 pure silver wire on big nanocrystalline cores.

The silver winding wire is brought out for direct connection to the circuit.  While I am a firm believer that it is the amp designers responsibility for the ultimate packaging aesthetic, I do have some 125mm cubed aluminum covers that will cover them if needed.

After many years of insisting that doing multiple taps only adds to the compromises I want to avoid in a design, I have finally come up with results that I deem acceptable.  Below are the plots of a similar transformer wound with the ability for 4, 8 and 16 ohm taps.

For behavior below 100hz I look at the inductance plots to make the best choice of inductance vs. current for the intended application and set the air gap accordingly.  The plots below were taken with the equivalent of a 16W excitation voltage @ 50hz.  Pink would be suitable for a parallel 300B,  Brown an 845 or GM-70 and something inbetween green and blue could be chosen for a 211.


Thursday, January 25, 2018

Nickel and Amorphous L1's

These just came out of the oven both for Choke Input power supplies.

The bigger one is on an amorphous core and weighs in at 14 pounds will find service in a GM-70 amp.  18Hy @ 250ma for a 1000V B+  The smaller pair are on 49% nickel and measure in at 100hy @ 20ma.
Autoformer for size reference:-)

Friday, December 22, 2017

Random says 17

and the winner is Hamingredient.

please contact me by email with which ones you want and where to ship them.

Happy Festivus to all!

Thursday, December 14, 2017

FFM..... festivus filament modules

It's beginning to look a lot like Festivus with all the airing of grievances and dancing around the Festivus Pole of late.   This must mean is time to give something away.  The newest thing in our bag of tricks is a simple LC filament module that can provide up to 2A or 3.5A of DC current.

Originally designed to power coleman regs, these modules give you a nice easy way to mount and wire a source of low ripple DC from an AC input.

All of the sordid details of what they are and what they can do can be found HERE

Air your Grievance in a comment below (with your name) for a chance at a free pair shipped to you as a Festivus Miracle.  As usual... in a few days Random.Org will pick a winner.


Friday, November 17, 2017

ETF 2017 - an attempt at documenting the main system...


hey kids... I am not even sure what to write about ETF.... but I think the big system represents the ETF spirit well - several cultures and personalities, working flat out both before and at the event, to construct a large and complex system that has never been attempted before, only to listen to music for two days, and then tear it all down never to be built again...

so in an attempt to document this before the memories fade away, here goes...

basically it was just a four way system that was quad amplified and used all line level crossovers.. this photo gives you some idea of what it was like in a front seat...

and Joe providing scale for the bass baffle...

so let's start with each range:

low bass - bass was jc's "heil air motion" bass driver loaded by the large angled baffle that Bjorn, Bae, jc, and "2 meter Peter" built... which in addition to loading the air pump, seemed to help break up room nodes... not sure of exact size... but maybe 2.5m tall by 5.5m wide... and the "driver" was composed of eight 15" woofers... played from below 20 cycles to 55 cycles.. big clean and kind of a "soft" bass... like a bass cloud that just sort of appears when it needs to... some of you subhorn people may know what I mean... this is a very good trait... very natural...

air motion transformer:

upper bass  - a pair of 15" Volt drivers per side... these really did hold their own.. even in teh large room and at quite high SPL... sealed box... lightweight and stiff... multiple materials for walls... thin plywood... and a sort of linen composite as the outer layer... also resin on the interior... very well damped...  played from 55 cycles to 300 cycles... and did so very well... 


midrange was jc's new horn made by Autotech in Poland... it is an Iwata/ le Cleac'h... Iwata's theory of horizonatal versus vertical dispersion and JMLC's math for the roll back.... and Dietmar made a carbon fiber throat adapter to extend it down to ~7/8" diameter to use his phenolic diaphragm, alnico magnet compression driver... similar diaphragms shape to the WE555.... played from 300 cycles to 3kc.... sounded quite good right from teh start... but it did improve... maybe not enough recent hours of play and it benefited from the workout... 


"tweeter" was mine... designed back in the Memphis days.. maybe six or eight years ago.. electromagnet designed with the expansion in the magnet to allow the JMLC flare to begin at the end of the phase plug... very fast flare/high T factor... 650 cycle flare... played from 3kc up... (thanks UK Pete for being the mule!) started off with really different voltages on the field coils due to one cable run being 5x the other, but once that was leveled and the supply voltage bumped up to the proper voltage, they seemed to be matched and extended exactly as designed... whew!

crossovers - for bass it was a DBX pro-sound that I think jc brought..  similar to many of that genre... 48dB/oct... we think... the midrange crossover was this really cool subractive unit that I think Blohbom designed and Ralf built... 6th order!... cool circuit..  for the tweeters, Bae whipped up a line level for me.. watching that dude work is inspiring... I said something about the need and he literally built this thing in his lap in two minutes... nuts!

amplifiers - Blohbaum built the low mid and midrange amplifiers...  I *think* they were his best pentode circuit... can't tell as he hides his wiring inside...
my amplifier covered the treble... you saw it in the last post.. so here is a shot of the output tubes.. Mayer has a lot of photos of the amp over at his VinylSavor blog...

and I must also show you what happened on the way over... TSA had their way with my amplifier... caps dangling... transformers wrenched... the solid wood board was literally split all the way down the middle.. I had to rebuild on the spot, and of course due to the long flight from the US, I was the last to arrive.. but all is well that ends well... the Lego viking held up the output stage and the TSA tape actually helped hold things in place... 

line and volume was from Karsten... a Slagleformer in the input feeding 8025's and then to a line output transformer... (sorry I forgot the photo)...

sources were mostly tape.. some vinyl, but tape was the ruler at this show... here is Bjorn's deck with a custom tape EQ using Slagle's nickel inductors...


and it was fabulous tape... Jimmy Smith's "The Sermon".. and great blues - Muddy Waters and Buddy Guy... just to name a few... 

oh, a photo of the subtractive crossover:

and *NO IDEA* why I have no photo of dave's field coil cartridge!  it played fabulously when we finally go it into the system Saturday night... 

and I asked these two if I could post their Joenet posts here... so here is Joe and JC:


Music is big. Most music anyway. Audio is usually a shrunken replica.
Yeah, that was a pretty good system...only *tiny* problem was that there
was not enough preamp gain to REALLY turn it up for 2 AM Deep Purple
tape listening. But then again, that is the kind of rig where it is
difficult to judge how loud it is playing because it is so clean. Surely
loud enough for any civilized purpose in that room, but sometimes you
just wanna go primitive! In that case, bigger and louder is better!
Magnify on!
That Buddy Guy "Live at the Checkerboard Lounge" tape was killer through
and through. Peak audio experiences like that can power me through
another year of enjoying whatever junk I have hooked up, knowing that a
greater world exists which I am occasionally fortunate to visit.
The 5 way definitely hung together amazingly well for a extra-complex
system whose parts had only just met each other. Although many of us are
seasoned "setup pros," no way that crazy assemblage could work out
unless the gods were smiling down on us, as I am sure they were.
It was especially gratifying to finally see jc setting up a speaker
since he routinely arrives after all the work is done at the Munich
show. ;op
There were many excellent and weird systems there, but for me ETF is a
social event, nay a social experiment. There is unexpressible tribal
power with 100+ maniacs all on the same page. By Friday night, we could
have taken to the longboats and invaded a neighboring country, maybe
Scotland, no problem.
All in all, a wonderful time! I spent a few days at DC Audiofest just
before leaving for DK and I was exhausted, even though I didn't do any
work and I could get there by subway. Four days of ETF with little sleep
and now I feel even more energized than before this intercontinental
audio marathon started.
Super great job by the Danish team all three years. Outstanding beyond
words. Guaranteed spots in audio heaven for you all. Maybe there wont be
40 virgins on the other side, but at least a couple randy MILFs and lots
of NOS tubes.
One idealistic concept that I always believed is that people know what
to do to create a better world if given the freedom and context to do
so, and ETF proves that to be a correct and essential assumption.
Now back to my boring life and my Dell sound bar...until next year.

 and jc:

the lecleach/iwata is marvelous. almost no ripple or horn sound. a bit of damping treatment and it's done. the improvement in horizontal dispersion is well worth the urinal jokes. and Dietmar is the world's best loudspeaker engineer, for me. i swear, five short sentences made this thing come together. all from him. not to short Heiner and his measuring gear! he really did speed things up and sorted level and phase. he is a wonderful piece of work! how many anarchist trickster shaman speaker manufacturers can there be? but i knew it would all fit because of Dietmar. who else has that much experience with 5 way horn systems. jeffrey does... but i think he will confirm what i say about Dietmar.
i've been working on this system for 3 years, but had no space or the resources to do it right. i asked jeffrey for a tweeter and advice for a rectangular JMLC horn 2 years ago! talking with him helped me build the one i did with the stage accompany... but 1000 Hz was too high for the volts and i knew i needed the midrange horn. i wanted a Sato or Iwata horn... and not a Western one. they are great but beam in the upper range. after last year at etf, i was sure i wanted a more modern math. and thought i could do a straight Iwata. i can. but it would have taken a long time.
unlike jeffrey and frank blöhbaum, i prefer the rectangular aspect for the mouth, precisely because of it's suppressed vertical dispersion. jean michel did the math for the hybrid Iwata, and when i saw autotech had made that, it was a no brainer. it does look like a toilet.
what can i say about frank?! he's the shit. i am not trying to toot my own horn, but except for a handful of others, who else is making analog amps with completely original circuits these days? it's down to a few worldwide. those MTA amps are the lowest distortion single ended amps by a long shot. the GM-70 amp is 40 watts at 0.05%!!! it makes 50 watts at something like 1%. knowing frank, that might be on the high side. those drove the Volts. the other amp, that drove the Iwata horns, uses the most insane power tube ever made. EL3010. 90,000 uMHOs ! 13 watts at 0.03% THD, single ended. there are very few people i know doing tubed gm amps. and the subtractive crossover! fixed frequency and sixth order bandpass.... all tube. not easy!!!!
Volt is my favorite contemporary speaker driver company. my first volt radial was back in the 90's... with the ATC dome mid and stage accompany. that system i made sold twice, by people who STILL use it today! i know the 12" but now also love the 15" PA version (lighter cone).
the bass bins are the culmination of my decades long loathing and disgust with the massive, usually MDF, "audiophile" boat anchor box. they are a 3/8" thick layer of 5mm finnish ply, amorphous weave coarse fiberglass, resin, and raw linen glued on with wall paper glue. the front face is 1-1/4" solid birch. the boxes themselves are super light. i will cop to being heavily influenced by the sound bar and the JBL7Harmon/apple plexy ball. never again a heavy bass speaker box! although, when all this shit was put together, it was fucking heavy. so what the fuck do i know?
jeffrey's tweeter was gorgeous! sweet sound AND it's steampunk! perhaps without him knowing it, there's definitely some jeffrey in this entire system, even if it doesn't look like it. we've been talking and arguing about it for a few years, and jackson can confirm this. those conversations are all in this. dietmar and jeffrey helped me a lot. even if we disagreed! i didn't always agree with dietmar! but he was always right...
dave slagle's autoformers and iron, are in there too! and we heard the electrodynamic cartridge dave made! fab.
but, for front end, tape had pride of place. omfg. björn's modified studer is just drop dead fabulous! it hurts! because that is a rabbithole i just can't jump into. no! but it beats phono. LPs have a ceiling. a hard stop. tape has something else. and things just sound better on tape. the norwegians also had tape running... from a pair of Revoxes. same story there
. fucking fab. their multiway horn system was also first class. more about that later.
martina brought her 401 with all that loricraft stuff. she is a turntable goddess. not to mention that she and jeffrey brought great records!!! the phono pre was from joachim gerhard. one of the best phono pre guys... the equal of curl, or burkhard vogel.that might be it. i'm just so grateful for the collaborative spirit that exists at etf and from the old tribe from nyc... we pulled it off!


all gratitude to the Danes... I cannot express what an amazing event these last three years have been... 


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