Saturday, July 20, 2019

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.


Monday, June 24, 2019

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...

Sunday, June 9, 2019

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....


Tuesday, May 14, 2019

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

.

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



Saturday, May 4, 2019

Schick Tonearms

.

This hit my inbox yesterday and I was dying laughing... it helps to know Thomas and his humor... super funny dude... and you never expect it.. it just comes out of nowhere... 

I have known Thomas for more than a decade.. back when his tonearm was just a DIY project for himself... a few ideas he wanted to try... (sounds familiar, huh?).. and all of these years later, I am proud to use his tonearms very often...  here is the always musical and yet so simple system that I use at the warehouse:


the tonearm has easy and obvious adjustments... clean lines...  you just add an autoformer and phono stage... front end done!  so simple... and then you just play records... 



and now we are a dealer... previously I have only told existing customers, just because they know that Thomas and I are friends... but I should really tell the world as they are not just insanely good for the money, but actually insanely good... contact me if you want to listen to one or get more information... here is his standard blurb:


___________________________

The tonearm is available in three finishes to choose from:

gold
silver (nickel + palladium, matte finish)
black (black chrome, matte finish)

There is a 12 inch version available as well as a shorter 9 inch (9,6inch).
The shorter version is a drop in replacement for EMT record players as well.

The price is 1499 Euro plus shipping about 25 Euro as insured letter.
A second, heavier weight for SPU and other heavy cartridges costs 45 Euros on top, if ordered together with a tonearm.
If you choose it as a single heavy weight there is no extra cost.
The tonearm includes a lift and arm bench.
All tonearms are equipped with an antiskating mechanism.

The arm has a 5 pin tonearm connector made by me. it consists of Teflon isolation and electronic test pins.

Else, you can choose a fixed tonearm cable, with lowest resistance and  capacitance, symmetrical cable with Neutrik RCA plugs.
The cable is 1,1m long.

All tonearms are equipped with an antiskating mechanism.

The tonearm is suitable for any cartridge from about 6 Gramm and a compliance value of below 20 µm/mN (22 for the 9 inch version).
That includes most cartridges on the market, excluded are only lightweight and very soft MM systems.
A headshell is not included. I recommend to use my graphite headshell for 249 Euros.









and don't forget:  Schick Happens! 

peace,
me

Friday, April 19, 2019

EMIA Permalloy 50 Amplifier

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rarely seen and never blogged, the EMIA 50's made an appearance at the warehouse for some final tuning and listening this week... two amplifiers are shown... one copper, and one silver... yes, silver interstage transformer and silver outputs... 


and check out those ridiculously giant nickel outputs... no, not 49% nickel... actual Permalloy - 80%.... sometimes I forget how much I love the sound of nickel... especially when coupled to a globe 50... not sure it gets any better than that... different maybe, but not better... a true classic... 


and speaking of rarely seen in public together, last night this happened:


Nick Mason played all 1970 and earlier Pink Floyd tunes... so wonderful to hear all of those Syd Barrett songs... and they brought the swirling chaos as well... Astonomy Domine... Interstellar Overdrive... Saucerful of Secrets.... and Roger Waters came out to sing the only song I wanted him to sing:  Heart of the Sun.... just perfect..   oh! and on the way out I found the Saucerful of Secrets:


I love me some liquid lights!


peace,
me

Monday, April 15, 2019

A.J. Musselman


I went to Walterfest X.5 last weekend and one of the coolest things was an unopened Musselman 5VCA from the early days that Pern had come across.  He thought it to be a precursor to the 112 but since the box was still sealed we had no idea what treasure was hidden inside.





Since nothing is too cherry to pop.... a crowd gathered around and the snail seal was broken





we quickly found out that this 93 year old was well documented and pern lamented about the chances of ever finding another.




Thursday, January 31, 2019

Digital Sand Bomb

In keeping with the "Bomb" theme here is something I have been playing with.  It is a Step up device based on the Nelson Pass Zen  I/V converter for a Dac.


Of course I have no use for resistive loads, coupling caps or anything digital so I dressed up the 2SK170 / 2SJ74 combo with a good dose of 80% nickel and feed it with a MC cartridge.


Yes this is a stereo pair with both input and output transformers and it loads the cartridge with around 10 ohms. 



Initial tests are quite promising.

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