New Stuff.

Sheltering at home has lead to a few new things in the intact arsenal.  First is a low ratio Speakerformer.  These units offer 1dB-6dB of attenuation in 1dB steps and the shunt resistor is changed with each setting to keep the impedance the crossover sees a constant 8Ω or 16Ω.  These will handle 20W of input and are designed for crossover frequencies of 100hz and above.

Next is something that fits in the middle ground between the Elmaformer and the basic autoformer modules.  Many customers have been asking for an alternative to the plastic shaft found on the entry level units without the cost of the Elma switched version. These are based on a 23 position Blore Edwards switch and offer a good compromise between cost and performance.

It should be noted that all of the autoformers are wound identically to each other and the only difference between the various versions are in switch type.

From the Archives

The archives in this case being a dust covered cardboard box on a bottom shelf in the far corner of the 'Lab'.

The chassis work by Melissa & Doug represents the 'Early Davey Functionalist' era that predates the 'Drug thru the Hudson' look of the early 21st century.

It is a simple remote controlled 100K linear pot attached to some RCA plugs used explore loading options for MC cartridges.  At one point the concept piqued the interest of a well known Stereophile reviewer but upon borrowing the unit, he was terrified to plug it in to his system so into the archives it went.

The remote controlled pot was the handy work of of our good friend John Chapman and the concept evolved into the Opti-Load which replaces the pot with a relay controlled resistor matrix.

ERC in the NY Times

We love to see it when friends get the credit they deserve!  The NY Times did this nice piece on what Pete Hutchison is doing in London with his Electric Recording Co.

Pete also owns peace frog records for a slightly more contemporary vibe.

Shameless Plug.

I updated the Intact SUT page to better represent the current state of affairs of what is going on inside the Intact and EM/IA MC Step-Ups.

Random Says.....

this is where it gets crazy,  I just sent a 90 pound shipment to Ngan and the cost was $230 using fedex great rates.  This was nearly double the $130 I was quoted for my initial guess of 120 pounds so I started asking questions.  Turns out there is currently a price break at 110 pounds so adding 20 pounds of "weight" dropped the shipment cost to $118.  I asked if I could just claim 110 pounds and ship 90 and they replied my rate would be declined and I would be charged full price at 90 pounds which is like $1800.  This meany I needed to start throwing weight into the box and a pair of the 1dB speakerformers was part of that weight.  I figured some would say the fix was in since the units are already in Hong Kong so I hit up random again and Jason gets to see if they go to 11.

I must say that jason is one fine looking guy so shoot him a congrats if you see him floating around the interwebs and tell him to send me his address.

FREEkerFormers

Ok... poor play on words.  I just updated the Speakerformer page with some more fake news on why you need them.  I also added a "Rshunt" calculator and two new tapers.  One is a middling version that does -6 to -15.5dB and an "I don't know what I need" version that does from -1 to -20dB in 1dB steps.

Up for grabs is a pair of the 1dB per step versions pictured above just wash your hands for 20 seconds and leave a comment with your name or some sort of identification and random.org will pic a winner in a week.

stay safe

The worst resistor ever?

I wound some 2KΩ copper wire resistors for DHT Rob a few years back and he used them to bias a 10.   He reached back out to me to do some 1300Ω to bias an AD1 @ 35ma.  

These got the slightly nicer package pictured above @ 25mm X 25mm. One of the biggest problems with the copper resistors is the value is not stable with temperature.  My solution to this for this case is to let them make some heat to stabilize them when in operation.  These units have a cold DCR of 1140Ω when cold and 1302Ω after an hour at 35ma.   Since these are intended for cathode bias it must be noted that the tube will run a bit hot initially before the temperature comes up and things stabilize.

The units are wound to be non-inductive and that results in a fair bit of parallel capacitance.  Since there will be a bypass cap in parallel with the resistor anyways, that is of little consequence.   In a crazy world one could use them unbypassed to compensate for loss of HF info elsewhere in the amplification chain like Kondo did with the Ongaku.

The other use for this idea is the loading of MC cartridges.  Since the proper way to load a cart is at the primary of the SUT, the values are typically much lower.  Knowing that it is also at a point where linearity of value across the audio band is a concern.  Here are some units that I wind onto an RCA plug for ease of termination and use.

These have much better bandwidth and are flat through the audio band.  Unlike the 1300Ω units which go capacitive at high frequencies, these go slightly inductive. 

The big question is why go to these insane lengths when there are plenty of off the shelf options are available?  Well if you look at it on the most basic level a resistor is simply a really crappy conductor. Given the extremes we go to for the quality of our signal wiring it isn't beyond reason to me that a longer length of a superior conductor with all of the baggage that it comes with may be better than an alloy specifically done to impede conductance.  Or you could just listen and damn if they don't sound good.

dave