Sut Selection (Why I don't do a one size fits all unit)

I just recently had a customer ask for a single SUT to match three different cartridges with a range of internal impedances from 1.5 to 15 ohms.  While that range is seemingly small one only needs to look at the frequency response plots to see why I like to match a impedance to a transformer.

These are the plots for 4 different cartridges (2r, 6r 9r and 15r) all feeding the input of one of our phono stages.  This particular SUT was designed for a 10 ohm cartridge and once that is known I was able to wind it so that the cartridge stayed well behaved to beyond 100Khz and only had a slight attenuation at 10hz.  I would be comfortable uning this cartridge in the 6-15 ohm range but if I were to drive this transformer with a low Z cartridge like a Lyra Olympos SL, suddenly a 10dB peak would appear above the audio band.  In this case, since this peak is happening at close to 200Khz one could argue it is sonically benign but armed with the knowledge that a 2 ohm cartridge will be the source I simply adjust things to minimize the out of band resonances like in the plots below.

I know there are those that will argue that adding a snubber network to the first transformer driven by a 2r source can eliminate the ringing and give a very beautiful frequency plot but somehow doing that also steals a fair bit of the music along the way.   For more of my thoughts on loading SUT's take a peek at this.

Stop the Insanity

We have been playing with the high voltage supplies on the "direct drive" quads and on a whim we tried some higher valued caps that the "stock" 0.001µf values.

I just happened to have a bunch of these 4µf caps and we gave that a go and things improved.  Onward and upward we went in values to see if there was a limit we could exceed.

10µ was better than 4µ and I think it may have had something to do with the Italian made capacitors which are obviously audiophile approved which can be seen by a closer inspection of the brand.

25µ was next and again for some reason things got better so next up are these banks of 50µ @ 900V caps.

Stay Tuned (or come listen to them in early November at the Capital Audiofest.)

I See Dead Cartridges

A friend dropped over a baggie of dead cartridges and I have been slowly bringing them back to life.  The first was a DV-20 that simply needed a cleaning and a new cantilever.

After that came the Allaerts which needed a fair bit more work in addition to a new cantilever.

Both are sounding good and next I tore into the Field Coil cartridge that met an untimely death last spring.  This one needed a new suspension, the coils rewound and new stylus assembly.

it is definitely a face that only a mother could love but it sure makes music!  Here it is pictured with a 103R getting a new suspension just prior to the aluminum cantilever being amputated and a Boron cantilevered Microridge diamond being put in its place.

Emia Manual

We are slowly moving Emia into the 20th century and just added a new Manual Autoformer as an entry level product.  It is dual mono and does 0 to -52.5dB in 2.5dB steps.  Two inputs and parallel outputs adorn the back and that funny knob in the center does a penalty free balance of 1.25dB and 2.5dB left or right.  Moving beyond the need for a 2.5dB shift the mono aspect will allow for any offset desired in 1.25dB steps.

It is essentially a 5-1/2" cube with enough mass to be stable and to really put things over the top it ships in a hard case.

Walt-A-Lago

Spent last weekend in the land of walter an neglected to take pictures so I'll just give some brief observations and a funny story.

We converted the 8 RCA MI-1432 field coil drivers from Lambda power supplies to Tungars and that really seemed to help the authority on the low end.  I also was able to try the LCR tape EQ out on the Studer A80 with some awesome source material and lets just say there is a huge amount of promise to the use of LCR for Tape EQ so stay tuned.

Now for my highlight of the weekend.  I took a bunch of cull records up to give away and left them in the back of the Element with the hatch open for folks to thumb through.  Since no good deed goes unpunished, upon leaving yesterday I found a car with a very dead battery and no jumper cables in sight.  As Walter was calling AAA for a jump I was thinking of fabricating some jumpers from a 500 foot spool of belden mic cable in the garage.  The car was parked such that the run would have needed to be 20 feet or so and while possible,  I thought why bother since a truck was on the way. Being a little slow on the uptake and staring at the 120VAC mocking me 6 feet from the thirsty battery I did finally recall  the original purpose of tungars. A field coil supply and two runs of mic cable had the car purring like a kitten in about 15 minutes.  Alas my car bitched all the way home about the flavor of the alternator electrons compared to the sweet taste of tungar.

last pair of the ElevenHorns!

.**SOLD**

found a pair in the move!

dark mahogany with light gloss finish

(the light exaggerates the gloss)

and now I know why I boxed them away... small

blemish in two spots... looks like this one was

dropped after stain was applied, but before the oil

was applied... 

spot #2 - and each of these is only noticeable up 

close... you will never notice from the listening 

seat.. but refinish if you want to..

1" throat, 600Hz Le Cleac'h... I sold out of these first...

generous roll back... for a big, open sound... 

folks have used them with TAD 2000 series, but

there are sleeper cheap drivers like the baby Radian!

list was US$950 - last pair as shown - US$425

experiencemusic "at" hotmail "dot" com

                peace,

                me

Speakerformers

Resistance isn't futile... It is downright evil!  One of the big offenders in the resistance camp is the humble L-pad so here is a magnetic solution.

This particular unit goes from -6 to -16.5dB in 0.5dB steps which is perfect for padding that horn down to the bass.  The "coarse" steps are 1dB and the toggle allows for a 0.5dB trim.

Of course it resides on a permalloy core and allows the end user to select the desired impedance presented to the crossover by selecting the shunt resistor.

Wiring is simple with the same 3 connections as an L-pad.  More info to come!