Capital Audiofest

Another year, another sleepless weekend in DC.  Here are some pictures from the room and links to show coverage.  Pete Hutchison of The Electric Recording Company sent over a test acetate that he cut of Sonny Rollins Way Out West which was sublime.  We were running 301's, a Schick and a Schröder with lots of silver and mercury.  I'll let a few pictures do the talking and those that write professionally tell the tale.

https://www.stereophile.com/content/emia-re-visioned-quad-esl-57s-loudspeakers-garrard-301-turntable-shroeder-and-schick

We were also showing the 50 amps, Autoformer, LR phono and SUT's in the Refined Audio room.

https://www.stereophile.com/content/cube-audio-mini-nenuphar-loudspeakers-emia-audio-electronics-tw-acoustic-raven-gt-turntable

Jack Roberts blurb on the Audio Beatnik

https://theaudiobeatnik.com/caf-2019-the-emia-room-and-stacked-quads/

16" Mag Chunk

Back from Capital Audiofest and settling in.  Until a full show post is ready I'll tease you with a work in progress by the good Dr. Khan.  The past few years we have been using a 12" Dymondwood uni-pivot arm which is affectionately known as "The Chunk"  Not to be outdone we were working towards a 16" table to play some ERC Acetates so a 16" model was started out of a plate of Magnesium.

Two versions are being done, one smooth and one with a pattern much like a nail file to break up resonances.

These things look much more like ninja tools than tonearms but that is part of the fun.  I guess one could take it another direction and say it could be used as a pledge paddle for the EMIA fraternal organization.

Here is a photo with a ST 50 in it for scale.  Next time I head down to DC it should be finished and mounted so stay tuned.

Jeffrey was searching for show coverage on Sunday and it appears as if the first hit was spot on topic.

Sid Smith's ESL speaker

I received a call from Ijaz to go pick up a piece of equipment from Sid Smith's son in law in New Haven, CT.  Many years ago Sid built an electrostatic speaker and I was to get the wire bending machine he built to make the stators.  Below are some pictures of the machine and what it was used for.

Apparently a successor to this speaker was shown by Joe Grado at the 1968 Philadelphia Audio Show and in today's dollar it would have been a $5700.  It is unclear whether that id for a single or a pair but even at double it is still a fraction of what the market commands today.

dave

THE horn loudspeaker reference book

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their official blurb:


Bjørn Kolbrek and Thomas Dunker announce the launch of a new website on the occasion of publishing "High-Quality Horn Loudspeaker Systems". As of September 12, 2019,  www.hornspeakersystems.info should be the first stop for updated information on the book release and for background information and resources related to the book and the research behind it.


but here is what I have to tell you... this is THE book... I have seen snippets... discussed a few of the findings.. the level of research is deep and wide... the curation is incredible... and the layout is clean and easy to comprehend... yes, they are my friends, but seriously, if you care about high fidelity music reproduction, you will snag this book the instant it becomes available.. (Amazon or AES NYC)....


something like five hundred pages of history - like Bell Labs classified technical papers that have never been published... several hundred of theory - Bjorn is the king (no offense, Dunker).... and a couple hundred on application - something these Vikings are extremely good at... so yeah... a THOUSAND pages.... wanna be freaked out?  here is a link to the Table of Contents...


I already know a few of the secrets within and cannot wait to read the rest... not much building will get done this October and November... but lots of work will get done after reading... motivation!


I am proud to be their friend and very proud of them!... sincere thanks for putting in the work....


peace,
me



Seeing High Frequencies

It has always puzzled me that adding a super-tweeter always seems to add "air" to a soundstage even for people with hearing that doesn't get past 12Khz.  I once posed this to Dick Sequerra and his response was that you can't assume that the ears are the only inlet to the brain for sonic information.  He went on to say that the ocular cavities are a major entry point for high frequency info.  I thought about this for a while and then filed it away to some deep dark corner of my brain to digest at a later date. 

Recently I came across this article  that puts forth a plausible explanation into this and seems to tie in with other reports of listener fatigue from systems where the "highs don't sound right"

I have also always noted the recommendation for eye protection when using ultrasonic cleaners and always thought is was just a "belt and suspenders" safety thing for possible splashes. This opens up a whole new concern given the popularity of ultrasonic cleaners for vinyl.

SIT on it

Back in my younger days in Milwaukee I used to hang out with Arthur Fonzarelli drinking Shotz beer talking about music and all of the cool things in life.  Today we have the interwebs and these conversations now occur worldwide.  One of my good customers in Hong Kong was interested in some SIT (V-fet) amps and with curves like a triode I had to wonder why I have yet to hear a V-fet amp with a nice DHT sound.  I offered to do a pair of nanocrystalline cored transformers for the Tonkin 2SK180 and then things got a bit out of hand.  Here are three pair nano of outputs ready to be packed up.

I had the idea that maybe much of the lacking sound I have experienced from my limited exposure to amps with these "triode-esque" devices had to do more with the with the circuit than the devices. We figured the first place to start was the power supply which needed to be choke input with amorphous cored 250mhy 2.5A chokes.

Next came the issue of driving the ungodly 2.5nf of input capacitance these devices have.  Historically an active buffer and fixed bias is used and I figured it was best to go with what was known to work and suggested a 417A into a 49% nickel 4:1 stepdown transformer.  Then it was suggested that maybe a Telefunken RE404 could be used and of course 80% nickel too.  I had spice crunch some numbers and sure enough for this particular case the DHT would do it.  The problem became actually getting a wide bandwidth 200hy @10ma  4:1 done on an 80% core.   Since there will be Coleman regs on the filaments I figured why not run that 450ma of high impedance current through a tertiary winding on the 4:1 to null the current through the primary?

The resulting 4:1's have a 200hy inductance with a window of operation of 7-11ma and when all put together this amp should have -1dB points of just under 20hz to around 40Khz.   Bias for the 2A of output device current will be in the form of a 7-8 ohm source resistor and bypass cap.  In the future this can be compared to fixed bias through the transformer secondary.

Stay tuned...

Ortofon Cutter Head.

Pete at ERC sent me an Ortofon cutter head to look at because it wasn't sounding right.  Since I have been looking at how various stylus profiles fit into the groove it was a perfect thing to get under the scope.

This is a beautifully made piece and here are some pics of the important parts.

In looking at it I saw that the cutting stylus didn't seem to fit snugly in place which could explain the reported dark and lifeless sound.  Below  is the ruby cutting stylus holder with the nicrhrome heating wire.

This tapered piece fits into a bracket attached to the drive system.

this interface didn't seem as structurally sound as it should be and closer examination revealed a problem.  It seems that there was a small 'ding' in the receiver hole making it somewwht less than round.

this minor dent kept one side from seating properly and gaps on either side can clearly be seen.  given that the irregulariy is only about 0.001" it will be quite easy to clean up.

For reference, this is how tightly the other side fits.

In general the aluminum piece does not have the 'watchmakers quality' that the rest of the unit has so I suspect it was a replacement part.   Once I get the word to proceed I will clean it up and get it back to Pete to cut a few lacquers and see if things improved.

stay tuned....

Craigslist... and I *swore* I quit doing stuff like this....

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so dave sends me a text that includes the above photo... I instantly see the Western Electric triode logo on the sides of the boxes peeking out from the CBS sleeves... and before I could reply, he follows that text with this one:

wow!  that is just about the best tiny tube that I know... a nice score... hmm.. I haven't looked at Craigslist in a long while... I swore off acquiring piles of old things that are not for very specific projects... but what could it hurt to look?  after all, Dave just added some nice and small items to his collection... so maybe just a peek....

and I saw this listing:

dang it!  no reference in the listing, but there it was... zoom in:

clearly an Altec horn.. and a pair of 15's... could be JBL, but considering the Altec horn, probably just a 421 woofer... and who knows what below it... but I was waiting on UPS for parts, and everybody knows I need to get out of the shop every once in while so that I do not go crazy, so off I went... 

I got there on time.. the one hipster in front of me went for the records... sucker... you could tell from the front albums that it was all standard classical... so I instantly haggled the guy for the speakers... but what I did not realize is that this was actually quite an awesome system... I would have loved to have hung out with this guy and listen to some big classical.. shown is just one stack in one corner!  this was a giant stereo rig... four Altec 15" per side... eight total!

so heavy... my back is trashed... hauling these up from the basement was *dumb*... and now to play Tetris... these have to fit in the official HiFi Hauler:

missed it by just over an inch... so that last bit of free space is the passenger seat... so I rode with a bass cabinet as an armrest... 

(shoutout to the baby blue pig that is my partner in crime for these adventures... he rode on top of the cabinet...)

so what was in the cabinets?  honestly I have not opened them up yet... gotta get back to soldering... but I was able to snap some shots inside the ports...

and the compression drivers:

so the entrance to the warehouse now has a wall of sound.. 

to which Iain said, and rightly so, "Is that Freedom Rock, man?".. to which I had actually forgotten the official response, "Then turn it up!"... 

I think dave really won this Craigslist "battle"... his tubes take up no space... his deal likely took ten minutes.. and my back still hurts.. 

oh, and don't tell Lisa... 

peace,

me