blink blink blink

 I mentioned the Feral Eye a number of years ago and the fate it met from Hurricane Sandy.  It  was brought back to life by steve berger as a PP 10 amp with a 49% nickel phase splitter and last night I got to hear it with a quad of mesh 10's from 1929.  

I'll be he first to admit that historically  I have not been a fan of either push pull or 10's and these days my daily drives are PP 300B's direct feeding stacked quad 57's and last night has me considering revisiting the 10.

The days events were to listen to cartridge variations and the mesh came in at the end of the evening as a treat for a hard days work.

Black Freeday

 Not many thinks kicking around lately that need new homes but these might appeal to a few of you.

A customer needed some naked speakerformers that went form -3 to -7dB and I inadvertently calculated and wound a pair that were -3.5 to -7.5dB.  Rather than bin them for the copper I figure someone here can put them to good use.  Full details of the concept can be found here.

leave a comment with a way to identify you and random.org will pick the new owner mid next week and of course I'll cover shipping.

dave

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...

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

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.

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.

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

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:-)

a sweet permalloy pea wrapped in silver.

On the micro level here are a set of silver LCR inductors ready to be put in their pod to ship.

 Once in their pod they look like this.

 Now consider some may want pods with different flavors.

As much as I like peas filled with silver, most of the time permalloy peas are copper.

Now that the phono correction is taken care of for customers in three different parts of the world... lets add the attenuation pods in silver.

I broke the mold with the 6X box and regret it.   I had to go find an odd-pod friendly box.

46 silver peas and 20 copper peas ready to go into 3 bigger pods to ship.

EMIA Phono Specifications...

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hello boys and girls... dave and I decided it is time to post some information about what is inside those petite minimalist boxes that have been showing up at HiFi events the last year or so.... the first batch is sold out and was very well received... that means it is time for the next batch.. which also means we need to tell you what is hiding underneath the hood...

 [the two boxes on the bottom are the phono stage - power supply and signal chassis]

basically, this is anything dave and I would build and endorse... heavy... tube rectified... choke input... single ended... direct coupled for high resolution... and what we feel is a very novel method of implementing the RIAA equalization... it removes the giant series resistor that is always a dynamics killer... and of course no feedback... the official blurb is:

The Emia phono is a tube based medium gain MM phono stage that uses a pentode input tube directly coupled to a triode output tube with shunt RIAA correction and zero feedback. This phono allows a wide range of tube types to be used without altering the RIAA characteristics. By simply rolling in these different tubes, the sonic signature of the preamplifier can be adjusted to taste. External plugs allow easy access to nearly infinite adjustment of loading for MM cartridges or external MC step up transformers.

EMIA Phono Specifications
____________________________

MM RIAA phono corrector

two chassis construction for isolation of power supply


direct tube input directly coupled through shunt equalization
to a single triode output stage

[signal path is wire, tube, wire, tube, capacitor!]

tube rectified, choke input power supply
dual inductive filtering with permalloy [nickel] final filter stage

Supplied with 6J11 for V1, 5687 for V2

Alternate tubes:
V1 = 7788/e810F, 7721/D3a , 7722/E280F, 6688/E180F, 6J11, 6E6p
V2 = 1/2 5687, 6900, 7119/e182cc, 7044
V3, V4 = 6DA4/6DM4 rectification

gain, 42-48db depending on tube selection. 42dB with the 6J11 / 5687

input impedance = user defined
output impedance = 2000 ohms
max input voltage = 200mV RMS
max output voltage = 25V RMS

net weight = 38 pounds/ 17kg

110/220V operation standard

_______________________________

Available in either black (below) or mocha (above)....

contact Jeffrey or Dave and we will direct you to your distributor...

thanks!

Peace,

Me

 

Emia Strain Gauge

It has been a long time in the coming but the first official Emia strain gauge phono supply is ready to be delivered.  It holds true to its "drug through the hudson" brethren with a couple of new tricks.
The need for biasing has been done away with and it is now simply plug and play as you roll through tubes to find the "tone" you want.  Also two switchable filter sections have been added to bring the riaa EQ closer to the ideal.  The beauty of the way the filters are designed is that they are relay switched shunt filters so when they are in the off position there is no sonic penalty to be had.

The average panasonic gives about  +- 2.5dB accuracy from 100hz to 10Khz and has rising response on either side of that.  The first filter addresses the 100 -10K range and uses a permalloy inductor to bring things close to +-1dB.  I was able to get it to +- .5dB but it reached the point where I felt the filter was killing the overall beauty of the strain gauge sound so I backed it off a bit to where I felt it listenable again.  The other filter section is in place to tame the rising high frequency behavior and even though the plots are not that different, the results are quite audible.   My preferences are for both filters to be out but others may feel differently so the option is there.

below are the plots I measured to show the three response curves of the various filters. (the filter robs about 3dB of overall gain and the plots are normalized to a 1Khz level)

For those who look at the measurements and don't read the above text...I want to be clear that I was able to get much better measured response (hell I could nail it) but the sound suffered so I backed off to get sound I would accept putting my name on.  I still prefer the sound without filters and now you have an option of hearing both and deciding for yourself.  Luckily in some circles junkies with differing tastes can still enjoy their high.

Permalloy!

We took a 50 amp to the LSAF with some 80% nickel outputs on it that will do a nice 2-3W full bandwidth, (amp is -1dB 22-54Khz).  When CV was over a week or so back he just had to hear what the 80% did.  At this point it was past midnight and he was bleary eyed but he encouraged the swap.  I had some 5K:8 bobbins so all we needed to do was stack'em up and clip 'em in.

Interestingly enough, the bobbins I had on hand were for a double stack of lams so we are talking 10 pounds of high nickel and copper.  In the picture above you can see them on top of the big amorphous OT's I was previously running.   I have really only heard amorphous shine when used as outputs on thoriated tubes and I have no use for it in low level situations.  Thoriated + amorphous, seems like the wrong blend of spices but it has proven to consistently work.  The few times I tried 49% on the thoriated tubes (49% is sublime with 3A3's 45's 50's etc) I always went back to the amorphous so I didn't have the highest of hopes for the 80% but shines insisted we push on.

I'll let him comment if he wants but I have to admit I was surprised.  The 80% let so much more music out of the groove in the form of a huge 3D image. We were both beat so we crashed and sprung up the next morning at the crack of 10am and gave it another comparison with the same results.

Shameful Shameful Shameful.

a few thousand words of shameful self promotion of the Kahn LCR.  Although technically I am not promoting myself... so what the heck.