Binaural

This is another one I haven't seen before.

  

This nicely pigmented album only appears to have two tracks but in reality it only has one since it is a binaural recording which requires two cartridges to play it.  This means you need a tonearm with two headshells,

The arm appears to work like a linear tracker and may have been the inspiration for the Garrard zero 100.  Here is a crude video showing it in action and some liner notes.

B is for Boron

Best taken in 4.4mm doses.

High Current

Lets pretend I have a friend who is in need of some 2.5V @ 25A filament transformers.

It seems you can scour the world and not find an appropriate beast when in theory it is really a pretty simple job.

Simple... Just take an $18 100VA antek toroid and pull off the secondary.  Then all you need is 12 turns of #9 wire and you are done.  Since the final use needs to do 2.5V @ 25A * 2,   I was a bit concerned that the extra 25VA over would be problematic.  My first go was using some #10 wire I had which gave me 10 turns for an experiment.  The next problem was how does one draw 25A of current?  since I didn't have any 0.1 ohm 100W resistors I had to make due.  Luckily in my junk bin I had a 10 pound spool of #20 nichrome wire so a few inches should do it.  Well, that got really really hot really quickly but three strands in parallel about 8" each did the trick.  The #10 showed promise but I was a few turns short so off to the "home despot" I went to get some #10 stranded house wire for round 2.

The stranded wire was a failure.  First, the nichrome wire gets really hot and copper being a good conductor of heat gladly wicked the heat back into the transformer.  For kicks I was able to flow solder into the junction of the two and the first few inches of copper got so hot that they could cut styrofoam through the insulation.  In reality, I suspect the #10 would have been fine but since I was already pushing the VA rating I decided to go for #9.  Luckily I have a few spools of #12 and a twisted pair of 12's = a single 9.

The black flecs in on the core are nichrome flakes from the making of the video but I have run the unit for an entire day with both windings drawning 25A  and it didn't get hot enough to concern me.  As an added plus the voltage didn't change as the units reached full temperature under load.

It is a bit of a shame that the #10 didn't work since apart from the "home despot" green, I also have three different types of #10 Litz wire.  Just think of all of the Audiophool Hype you could come up with as you painstakingly strip 420 strands of #36 per connection.

Audio Intersections.

I had the fortune to visit a house a few hundred feet from this intersection and thought the names quite fitting for audio.  On this visit I saw a few interesting things the first being this amp.

 That Marantz meter is really telling of the specialness of this particular amp.  This was the prototype for the Marantz model 5.  Another really cool thing was this 7C.

 The collector would probably scoff at the labeling on the back but this was Sid Smith's 7C so I suspect an exception could be made.
  

It also represents a relatively low serial number which adds to its coolness.

Resist!

So Johhny tried some 450 ohm copper resistors under his 75TL's and liked what they did so he asked for some 600 ohm versions for under the RS242 driver.

For the earlier 450 ohm versions I did both inductive and non-inductive wound versions and the non-inductive versions were preferred.  The interesting side effect of the non-inductive winding technique is a  bit of shunt capacitance but since the cathode R is bypassed, I say the more the merrier.

Solder Bars

I was getting a bit low on bar solder for my leaded solder pot so off to the 'bay I went.  The first purchase was 12 pounds of Alpha-Solder.

Unfortunately upon getting it I quickly realized it was lead free with a small 3.5% bonus.

Back to the 'bay for some good old fashioned lead solder and without thinking I bough these.

Now I have a bar of 60-40 and a bar of 55-45 that I don't have the heart to melt down.

Oh well.... To the 'bay batman....

New Toy

I always found it frustrating to be working with an automated limit of ~90Kz from my 192 sound card since the good stuff, particularly with SUT's always seems to happens above 100kHz. 

 

I have seen the Velleman pcsgu250 with its claims of Bode plots to 1mHz for some time and asked about experiences on a number of forums with no response.  I finally sent $150 to newegg last year and procured one.  Flash forward several months and i took some time to rewrite my excel macro's to import the data and I must say I am quite happy with the results.  Sure it is no Audio Precision but it is a million times better than manually entering 100 sets of coordinates per trace on the test bench.

Name that SRA.

I'd call it close enough to 92 degrees but the sound wasn't the greatest.  It was sounding really good until things abruptly went bad and a quick visual inspection explained the problem.

Note to self... hot glue and field coils do not play well together.

Hudson Valley hiking in March...

.

means hiking *on* the river...

as you know I moved to the Hudson Valley from Memphis before last winter... quite a weather shift... I heard from locals that last year was the coldest they could remember in decades.. "what winters used to be".. or "what winters are supposed to be"... it was cold... well, that was before this year came... we set a record in February - average temperature = 9 degrees Fahrenheit... not average low... average *temperature*.... whew... but you know what?  it is good for working.... and this past Friday when the sun came out, having long eclipsed forty hours in the shop, a few of us took off for a hike in the sun... it was wonderful...

we started off from the house.. hiked down Burget Creek... then onto the Hudson.. all the way down to Catskill Creek... and finally back to the Mill to finish up the day's work...

notice the crazy ice breaks.. the Hudson is tidal... and that makes for some really cool ice breaks...

obligatory HiFi Heroin photo:

peace,

me

finally got his 16-A....

... and Elmore James has never sounded better... 

initial placement

it is a Subaru thing

road trip!

yep... pile o' parts

random barn photo

final setup

repro 16a (better bends than any original I have seen)

original WE555's, single Coral tweeter

rebuilt amp (globe 50's), 416's bi-amped

shocking how good this sounds... you just sit there with your mouth agape... 

so much detail.. transients... and then you end up dancing!

*so* much fun....

peace,

me

Round Plates

This is a circa 1990 Alessa Vaic copy of a Marconi R-type and it has that beautiful round plate structure we have grown to love.

Unfortunately the tube has no emission and the real purpose for this post is behind the tube which is a set of iron for another round plate tube that does the R-type X 4... the 304TL.

The bigger ones are the SE outputs that can take 200ma of plate current while putting out 40 watts at 50hz.  They have bandwidth (-1dB) from 7hz to 49Khz and can do all of this due to the offset winding that runs the 12.5A filament current through the outputs in the opposite direction as the B+.  This brings the other two chokes into play which are the 20mhy 12.5A filament chokes that keeps the offset winding from loading down the tube.

The set of 4 weighs in at 46 pounds of copper and amorphous and boy am I glad the topic of silver never came up.

DIY Western Electric 417A Kit.

 A four+ year ebay hunt finally payed off when I bagged this little gem.  I first saw one down in DC at mikes place and from that moment I needed one.    According to mike, they made these at the factory and used the vacuum pump to get all of the air out.  The pics below are from some different angles so you can see all the parts.

proud papa....

in the realm of DIY, "proud papa" usually refers to pride in a work that you have created... in this corner of DIY, usually an amp or speaker... but in this case, I am actually a proud papa...

my oldest called me one day and told me that he found some gear... and this is the photo from his dorm room:

for scale, that is his laptop.. and yes, a full size laptop... I am so proud!

[and Happy New Year!  one of my resolutions is to start blogging twice a week.. I realized that I had been extraordinarily slack in posting when twice in the same week someone asked why I linked them to "dave's blog"... sheesh!]

peace,
me

Choke me in the shallow water....

...before I get too deep.

What is pictured above is 14 pounds of copper and amorphous in the form of some 12hy 200ma PS chokes.  The interesting little additional fact is they can handle 1000Vac @ 120hz without buzzing and will be used as L1 after some 872's in a GM70 amp.

Bjorn must be one unlucky guy....

with 13 as his lucky number it finally paid off.

contact me by email with your delivery info.

dave