Tuesday, August 11, 2015


My Audio GD Dac 19 was highly praised at the River City Audio Society meeting on August 8, decoding digital from a Rega transport and driving a Rogue amplifier.  After listing to a number of old vinyl records, they played a CD track from my collection, The Tango Boy played by sax player Jessie J.  There was jaw dropping silence lasting for a few seconds after it was over.  I was told it sounded open and analog from an audio engineer who said those were exactly the qualities he liked.

But actually I hadn't been playing it for several weeks.  I had hooked up the Audio GD to drive the Krell amplifier, and the Onkyo RDV-1 to drive the Aragon amplifier.  Because of summer heat, I've been using only the Aragon, so I hadn't been enjoying the Audio GD, though it was still running.

But the plan to hook up both amplifiers to the Audio GD was quickly started after I brought the DAC back home.  I had already obtained a custom set of BJC-1 cables from Blue Jeans Cable specifically for this wiring, along with barrel and Y adapters from Audioquest.

NB: the barrel adapter allows the male tip of the incoming RCA to plug into the male input of the Y adapter, which has one male and two females.  In my estimation a three female Y adapter is the most useful and with that the barrel would not be necessary in cases like this.  It's most reasonable to feed a Y adapter from cables on every side, plugging the big Audioquest Y adapters with heavy wires into any piece of equipment is going to cause very unreasonable stress on the equipment RCA jacks.  But for some reason the people who make these things haven't thought this out.

NB2: What I call "barrel adapter" is called "RCA coupler" by Audioquest and possibly others.  I learned the "barrel adapter" term from my friend George decades ago.  They were useful then too.  Now they are too removed from the simplicity audiophile magical thinking.  You want the simplest possible cabling.  Well actually, you do.  But hugely more complicated cabling isn't necessarily much worse.  So just a little complexity, to make things work, is just dandy fine.

The output from the Audio GD first flows through an 18 inch BJC-1 which reaches nearly to the ground.  The end of that BJC-1 is attached to the barrel adapter and then the Y adapter, which is almost touching the ground (and completely isolated from ground with a Dark Field elevator on one side, unfortunately I only had one left.  The other side is about half an inch above ground.  The Y adapter feeds a 2 foot cable to the Krell and a 7 foot cable to the  Aragon.  Thus to drive both amplifiers at the same time, the Audio GD is loaded by 10.5 feet of BJC-1, which has a total of about 160 pF.  That's actually less than the previous 4 foot (nominally one meter) cable I had been using, a Straightwire Sonata, which has 284 pF, just to connect to the Krell.  The Aragon had previously been driven through about 400 pF of early 2000's Radio Shack interconnect: 3 and 6 foot lengths tied together with a Radio Shack barrel connector.  I measured an early 2000's 6 foot radio shack interconnect as having 180pF.  I measured 2 feet of BJC-1 as having 31pF.

Closeup of couplers and Y adapters connecting two amps to one DAC

So I'm driving both amplifiers through far less capacitance than either one before.  These BJC-1 cables are marvelous.  Though intended to be entirely non-tweako (Blue Jeans is expressly non-tweako, the point is to sell top professional grade cables at fair prices, not magic cables at astronomical prices) these cables scratch many a tweako itch, featuring solid core bare copper wires (btw, most of my friends prefer pure copper to silver plated) and foamed polyethylene insulator/dielectric--which is next best to PTFE teflon.  The low capacitance and double shielding is great too even if non-tweako.  I should mention that I consider coax the Only acceptable coduit for a single ended voltage signal.  It does only harm to run a single ended signal in balanced configuration with an additional shield.  That's far more complexity and it actually works less well wrt shielding.  Coax has an inherent shielding characteristic, it's sort of like super-twisted.  The Only reason why network wiring switched to twisted pair with complex modems was to reduce cable cost: less copper.  A good coax like the BJC-1 will use a lot of copper in both the center conductor and especially in the braided shield--which is another requirement for decent audio cabling.  BJC-1 famously has two shields, one braided.  Inductance isn't a significant factor in line level cabling because of high load impedance, endless twisted or flat wiring is unnecessary and probably doesn't deliver the shielding or low capacitance as well.

I did at least think about the effect of the capacitance of one amplifier loading the other.  Because the inputs are high impedance, I don't think they express much capacitance.  Even if an amplifier were to have a low pass filter at the input, that would by necessity have to follow an internal resistor, and thus be isolated from the input cable.

Back of Krell with red and white BJC-1 connectors

Before actually measuring the capacitance of the Straightwire Sonata, I had been planning to order a pile of its closest current equivalent, Straightwire Chorus II.  It does the tweako big time but at incredibly low cost.  It features PTFE (which I consider the real Teflon, and not the Teflon FEP commonly used in plenum rated and audiophile cables because it is far easier to tool than PTFE) dielectric and solid core wire, with a good braided shield.  This seems to get the basics right.  It does have that silver plating I consider slightly worse-than-useless, but I'd overlook that and I could be wrong about whether silver is good or not.  It's hard, hard, hard to find real PTFE cables, and Straightwire cables can be ordered in lengths starting from 0.5 meter and increments of 0.5 meter.  Almost as fine as BJC-1, which can be ordered in 1 foot increments.

Aragon 8008 BB with BJC-1 and other cables on right

Living Room System seems to be sounding extra fine now, even though I'm still using the Aragon, I seem to be getting more than 50% of the sound improvement I had been mentally associating with the Krell in the most recent testing.  I did adjust the new level (by raising the subwoofer and super tweeter levels by 2.3dB) of the Audio GD relative to the Onkyo.  It technically does have at least 2.3dB more dynamic capability simply because of the higher output of the Audio GD.  But it sounds far more dynamic, as if the dynamic range has increased 12dB.  Rather than setting levels in the 90's I'm now setting them in the low 80's, and yet it is sounding louder.

While I was at it, I changed out some other cables.  I have gone from mostly Radio Shack cables in the Living Room system (yes, I don't believe cables are very important, and I believe that most often if audiophile cables sound different it is likely for the worse) to mostly BJC-1.  My ultra high end Denon DVD-9000 was connected through 6 feet of Radio Shack cable having high capacitance (about 200pF), mediocre shielding, and wrapped around lots of digital and power cords.  I used a 4 foot cable (minimum length) having about 80 pF (20pF/ft) of unknown maker for that.  The DVD-5900 I use for SACD was already wired with 17pF/ft mogami cables, but now I'm thinking that might be the perfect spot for the Straightwire with high capacitance  (help reduce the noise) and Teflon (a minimum of smearing relative despite the high capacitance).  Plus it's a high endy cable.  Putting my whitish hat on, the capacitance is not high enough (given the 100 ohm source and 20kohm load) to change the response for the worse audibly.  Only enough to count for audio fool magic.

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