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This is about a little "test" project that I just finished. I wanted to take a stab at putting together a "budget" set of high end cables for evaluating the M8 MKII currently in development. To understand where this is coming from, the goal was to make a full range speaker cable with as much of the general quality and neutrality of top end cables like the Cardas, with a performance goal somewhere between Cardas Quadlink Speaker cable and Cardas Neutral Reference Speaker cable. And of course, at much lower prices! The "budget" standard of reference I'm currently using are some DH Labs Silversonic based cables, which are quite respectable for the moderate cost per foot of the bulk cable. I also use this cable for internal wiring in speakers systems in some cases. So, my plan was to make a cable of the same length as the ones I have, and compare the two.
What else? How about readily customizable to the specifics of an installation- that is, for some amplifiers and speakers, either spades or bannana plugs may not be an option. For example, my Ayre V-5 uses a Cardas clamp binding post assembly which won't work with bannana plugs; spades are a must. In other situations, requirements may be reversed. Plug and Play connectors, which means WBT; there really aren't any alternatives I've found with similar flexiblity. For "fixed installation" cables I favor Cardas connectors, but they are always soldered.
What's important in a speaker cable?
This is an interesting and non-trivial question; you'll get as many different answers as there are cable companies, I think. Some fundamentals I think we can hold true, though, laying aside some of the mumbo jumbo and slick talking brochures.
First, the lower the resistance, the better- this is especially true for speaker runs over two meters. This generally means that we'll be looking for aggregate wire guage of 14 AWG or lower, depending on the cable lenth.
There are some interesting cable "receipes" available on the 'Net- probalby some of the best known are Steve Rochelin's. Many have reported satisfying results making hand braided speaker cables, (which reqiures the larger part of a whole weekend!), but me, I'm just not that masochistic. However, I've worked with braided cables to reduce inductance and RFI pickup since the 70's, and purchased the first "tweak" cables that I'm aware of using this technique in the mid seventies; they were imported from Japan by Polk Audio, of all people; I still have some of that magnet wire based cable around. But for this experiment, after researching what was available and what I could find to buy in bulk, I settled on Kimber 8TC bulk cable. This uses eight very high purity copper conductors with teflon insulation for each polarity of the signal, in a woven matrix to reduce inductance and RFI pickup.
The aggregate resistance of this cable is rated at 9 AWG. This seems to meet the resistance goal. The woven braid reduces inductance considerably compared with twisted or parallel pairs- how much, we'll have to wait and see when the finished cables can be measured.
For the flexibility of their crimp and Torx screw connection system, I chose a set of WBT spades and locking bannana plugs. The actual work involved here is not that bad- first, unweaving about 4" of cable, and stripping the ends by seven tenths of an inch to prepare for the crimping and soldering operation.
After stripping and twisting the cable halves, a crimp tool is used to crimp the bare copper leads into a WBT AWG 8/10 crimp sleeve. There is a bit of excess space, and a handheld tool doesn't really produce a high quality gas tight crimp, so I follow up with Cardas Quad Eutectic solder fed into the open end of the crimp assembly. The Quad Eutectic solder is made with lead, tin, copper and silver. It's strongest property is that it doesn't slurry when cooling, and it makes virtually absolutely perfect solder connections every time. This stuff is the best, in my opinion; I don't use anything else any more, for anything.
The next step, nearly finished, is heatshrink protection for the wires- I like the Kimber wire colors, and maintained that with my choice of heatshrink.
For protection and to avoid pickup up dust or dirt in the cable, I also sheathed the finished cable with Alpha polyester braid; I popped for the more expensive GFP 120NF 12 braid, which is "anti-fraying", and doesn't require a hot knife to cut. Here is one of the finished cables:
How well do they work?
First, I did some basic measurements of the DH Labs based cable and the new one. I measured the inductance in "loop back" mode, that is, it measures the inductance at one end, with the other end shorted together. This gives a good measure of the series inductance which the amplifier/speaker combo sees with a given cable.
Then, I open the far end of the cable, and measure the capacitance. This gives a measure of what added capacitance the amplifier must drive; unfortunately, most power amplifiers should be happy with at least a few nanofarads of capacitance at the output terminals, however, some high feedback designs don't even tolerate that well. Last, for comparison, I measured the resistance of one leg of the speaker cable- this can be doubled for the total resistance in series with the speaker.
Measurements were made with my HP LF4192 Network analyzer; this is a really useful little critter, as it can measure at a wide range of test frequencies ( from 100 Hz to 5 MHz), and with or without bias voltage (adjustable) applied. It is a four terminal (kelvin) tester, with several test heads, so their aren't errors introduced from test leads.
The results were interesting, but actually a bit better than I expected.
DH Cable, 14 ft:
Loopback Inductance: 3.25 uH
Distributed Capacitance: 0.453 nF
Resistance one leg: 0.16 ohm
Resistance both legs: 0.32 ohm
8TC based Cable, 14 ft:
Loopback Inductance: 0.35 uH
Distributed Capacitance: 1.36 nF
Resistance one leg: 0.033 ohm
Resistance both legs: 0.066 ohm
This shows a nice combination of characterisitics, as the inductance is cut by an order of magnitude, while the capacitance is only increase by about 3, and is still quite reasonable in value. The resistance speaks for itself.
How do they sound? I have only had a brief opportunity to do any comparitive listening; I put a CD (jazz; "Classical Soul", ), played the whole disk, then swapped cables (without touching the stepped attenuator on the preamp) and played the disk again. My initial impression is that the bass with the new cables is deeper, better controlled, and slightly higher in level. More important, the midrange and top end seems more coherent, smoother, and less dark or hard. With the silver DH cable, it's as if there's a slight tip up to the sound, peaking around 3-5 kilohertz, with a slight roll off above that, and with some slight veiling in the midrange, plus the lighter bass. This could *all* be placebo effects, too, but extended listening will probably tell.
I'll have to get back with you on this one, folks, but so far, I think the results are close to what I hoped for.
Best regards,
Jon
After
Earth First!
_______________________________
We'll screw up the other planets later....
What else? How about readily customizable to the specifics of an installation- that is, for some amplifiers and speakers, either spades or bannana plugs may not be an option. For example, my Ayre V-5 uses a Cardas clamp binding post assembly which won't work with bannana plugs; spades are a must. In other situations, requirements may be reversed. Plug and Play connectors, which means WBT; there really aren't any alternatives I've found with similar flexiblity. For "fixed installation" cables I favor Cardas connectors, but they are always soldered.
What's important in a speaker cable?
This is an interesting and non-trivial question; you'll get as many different answers as there are cable companies, I think. Some fundamentals I think we can hold true, though, laying aside some of the mumbo jumbo and slick talking brochures.
First, the lower the resistance, the better- this is especially true for speaker runs over two meters. This generally means that we'll be looking for aggregate wire guage of 14 AWG or lower, depending on the cable lenth.
There are some interesting cable "receipes" available on the 'Net- probalby some of the best known are Steve Rochelin's. Many have reported satisfying results making hand braided speaker cables, (which reqiures the larger part of a whole weekend!), but me, I'm just not that masochistic. However, I've worked with braided cables to reduce inductance and RFI pickup since the 70's, and purchased the first "tweak" cables that I'm aware of using this technique in the mid seventies; they were imported from Japan by Polk Audio, of all people; I still have some of that magnet wire based cable around. But for this experiment, after researching what was available and what I could find to buy in bulk, I settled on Kimber 8TC bulk cable. This uses eight very high purity copper conductors with teflon insulation for each polarity of the signal, in a woven matrix to reduce inductance and RFI pickup.
The aggregate resistance of this cable is rated at 9 AWG. This seems to meet the resistance goal. The woven braid reduces inductance considerably compared with twisted or parallel pairs- how much, we'll have to wait and see when the finished cables can be measured.
For the flexibility of their crimp and Torx screw connection system, I chose a set of WBT spades and locking bannana plugs. The actual work involved here is not that bad- first, unweaving about 4" of cable, and stripping the ends by seven tenths of an inch to prepare for the crimping and soldering operation.
After stripping and twisting the cable halves, a crimp tool is used to crimp the bare copper leads into a WBT AWG 8/10 crimp sleeve. There is a bit of excess space, and a handheld tool doesn't really produce a high quality gas tight crimp, so I follow up with Cardas Quad Eutectic solder fed into the open end of the crimp assembly. The Quad Eutectic solder is made with lead, tin, copper and silver. It's strongest property is that it doesn't slurry when cooling, and it makes virtually absolutely perfect solder connections every time. This stuff is the best, in my opinion; I don't use anything else any more, for anything.
The next step, nearly finished, is heatshrink protection for the wires- I like the Kimber wire colors, and maintained that with my choice of heatshrink.
For protection and to avoid pickup up dust or dirt in the cable, I also sheathed the finished cable with Alpha polyester braid; I popped for the more expensive GFP 120NF 12 braid, which is "anti-fraying", and doesn't require a hot knife to cut. Here is one of the finished cables:
How well do they work?
First, I did some basic measurements of the DH Labs based cable and the new one. I measured the inductance in "loop back" mode, that is, it measures the inductance at one end, with the other end shorted together. This gives a good measure of the series inductance which the amplifier/speaker combo sees with a given cable.
Then, I open the far end of the cable, and measure the capacitance. This gives a measure of what added capacitance the amplifier must drive; unfortunately, most power amplifiers should be happy with at least a few nanofarads of capacitance at the output terminals, however, some high feedback designs don't even tolerate that well. Last, for comparison, I measured the resistance of one leg of the speaker cable- this can be doubled for the total resistance in series with the speaker.
Measurements were made with my HP LF4192 Network analyzer; this is a really useful little critter, as it can measure at a wide range of test frequencies ( from 100 Hz to 5 MHz), and with or without bias voltage (adjustable) applied. It is a four terminal (kelvin) tester, with several test heads, so their aren't errors introduced from test leads.
The results were interesting, but actually a bit better than I expected.
DH Cable, 14 ft:
Loopback Inductance: 3.25 uH
Distributed Capacitance: 0.453 nF
Resistance one leg: 0.16 ohm
Resistance both legs: 0.32 ohm
8TC based Cable, 14 ft:
Loopback Inductance: 0.35 uH
Distributed Capacitance: 1.36 nF
Resistance one leg: 0.033 ohm
Resistance both legs: 0.066 ohm
This shows a nice combination of characterisitics, as the inductance is cut by an order of magnitude, while the capacitance is only increase by about 3, and is still quite reasonable in value. The resistance speaks for itself.
How do they sound? I have only had a brief opportunity to do any comparitive listening; I put a CD (jazz; "Classical Soul", ), played the whole disk, then swapped cables (without touching the stepped attenuator on the preamp) and played the disk again. My initial impression is that the bass with the new cables is deeper, better controlled, and slightly higher in level. More important, the midrange and top end seems more coherent, smoother, and less dark or hard. With the silver DH cable, it's as if there's a slight tip up to the sound, peaking around 3-5 kilohertz, with a slight roll off above that, and with some slight veiling in the midrange, plus the lighter bass. This could *all* be placebo effects, too, but extended listening will probably tell.
I'll have to get back with you on this one, folks, but so far, I think the results are close to what I hoped for.
Best regards,
Jon
After
Earth First!
_______________________________
We'll screw up the other planets later....
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