Improved SDA Interconnect Cables

[DarqueKnight]

SDA enthusiasts are well aware that relatively modest tweeks can bring substantial improvements in the performance of these speakers. Performance enhancements due to crossover components upgrades are well documented on this forum and elsewhere. Upgrading the SDA interconnect did not produce a "night and day" difference, but it did significantly improve the holographic 3-dimensional soundstage illusion.

A commonly overlooked tweak is the replacement of the SDA interconnect cable. Others who have made their own SDA interconnects have commented in general terms that there was an improvement in performance, but I never ran across a critical evaluation that gave the specifics. This modification was something I was initially skeptical about undertaking because I did not think the benefits would be worth the time and expense. After the installation of the first upgraded SDA cable, it was immediately obvious that this was something I should have done a long time ago right along with my first crossover modification.

With the upgraded pin/blade cable, the most significant improvement was in soundstage depth. There was no change in soundstage height or width. Instruments and vocalists were projected 1 to three feet further in front of (or behind as appropriate) the speaker plane.

With the upgraded blade/blade cable, again the most significant improvement was in soundstage depth. There was also significant improvement in soundstage width. After the SDA SRS and SDA 1B IC upgrades, intruments were projected out a couple more feet on each side.

With the upgraded SDA IC's, images within the soundstage had more "weight". The relative sizes of instruments and voices within the soundstage was more apparent. With well-recorded vocals, there was more of a sense of a real person standing in the room. There was a small, but very noticeable improvement in detail. For example, I could hear more of a singer's breathing between singing passages. Electric bass notes had more "growl" and "edge". The vibration of the wood body of the acoustic bass was more apparent. Piano notes had slightly more detail and sparkle. Instruments with a lot of high frequency energy (e.g. drum cymbals, saxophones) had more shimmer and detail. These improvements in detail were noticeable even when listening from another room.

Pin-Blade Cable Construction Details


Figure 1. A well-organized workspace is conducive to peace of mind and proper construction technique.

The stock pin-blade SDA interconnect is a 2 conductor 18 gauge gable. Only the pin carries a signal. Both internal wires are connected to the pins. The blade only provides a more secure mechanical connection. The stock cable was replaced with a 15 foot cable made from Monster Cable Z2 Reference speaker cable. The Z2's two 12 gauge wires were soldered together which effectively made its cross sectional area fall between 8 gauge and 10 gauge wire. Twelve gauge cable has a typical resistance of 1.7 ohm per 1000 feet whereas 8 AWG and 10 AWG have resistances of 0.667 ohm per 1000 feet and 1 ohm per 1000 feet respectively. Eighteen gauge wire has a typical resistance of 6.6 ohms per 1000 feet.


Figure 2. Upgrade cable for pin-blade SDA's.

The cable was terminated with Monster Lock pins which allow different terminations (bananas and three different sizes of spades) to be used. A Cardas CCGR-S binding post was installed just above the stock SDA jack for the new SDA cable.


Figure 3. SDA SRS 1.2TL: Cardas CCGR-S binding post as SDA IC receptacle.

Blade-Blade Cable Construction Details

I initially planned to solder a standard blade-blade connector to a heavier gauge cable. Ken Swauger provided the name of the vendor for their blade-blade connectors: Cinch-Jones Company (www.cinch.com). The part number is P-302-CCT. However, when I saw the large crease at the cable connector junctions of both of my blade-blade interconnect cables, I decided to go for the gusto and switch both the connectors and the jacks to something more secure and with greater cable strain relief. I chose metal XLR jacks for the cable recepticles and metal 90-degree angle XLR connectors for the cable terminations. Two of my SDA's, the SDA 1B and the SDA SRS use the blade-blade cable. I essentially replaced the small gauge blade-blade cables with larger gauge pin-pin cables.

The stock blade-blade SDA interconnect is a 2 conductor 16 gauge cable. Both the large blade and the small blade carry a signal. The blade-blade cables were replaced with Monster Cable Z2 Reference speaker cable (12 gauge). Sixteen gauge wire has a typical resistance of 4.2 ohms per 1000 feet. Twelve gauge cable has a typical resistance of 1.7 ohm per 1000 feet.



Figure 4. Metal XLR jacks and connectors for blade-blade cable upgrade.


Figure 5. Stock SDA IC jack of SDA 1B.


Figure 6. Stock SDA IC and jacks of SDA 1B.

The wires going to the SDA jack were somewhat skimpy. I decided to replace them with some Monster Cable 12 gauge in-wall cable (2R-CL) that I had left over from a previous home theater system install.


Figure 7. Inside of SDA 1B cabinet showing crossover boards and tiny wires going to SDA IC jack below. Note the larger Solen film capacitors and Mills resistors. This was my first speaker crossover modification.


Figure 8. Inside of SDA 1B cabinet showing replacement SDA jack and wires.

I do not know if the larger gauge wires for the SDA jack made a sonic improvement, but I subjectively feel better knowing that they are gone. Ironically, after I did the crossover modification for the 1B ( a long, long, time ago), I replaced all the internal wires (except the SDA jack wires) in one speaker. I compared the 1B with stock wiring to the 1B with heavier gauge wire and didn't hear a difference. The wire I used was DALI's (Danish American, Limited) 12 gauge High Resolution Speaker Cable. I reinstalled the stock internal wiring because I did not want to waste more of the DALI cable by rewiring the other speaker.


Figure 9. Blade-blade cable replacement with XLR (pin-pin) connectors.

The cable construction for the blade-blade replacement was more tedious and involved than for the pin-blade replacement. For the SRS and 1B, I had to cut a 7/8" hole through the back of the speakers with a hole saw. In addition to that, grooves had to routed out at the 3, 6, and 9 o'clock positions around the hole to accommodate protruding ribs on the XLR jack housing. A large notch of about 1/8" high by 1/4" wide had to be routed out of the top of the hole to accommodate the XLR jack locking mechanism. All of the opennings in the XLR jack were sealed with electrical tape to prevent hot glue from seeping into the jack and jamming the locking mechanism. The plastic inner housing in the necks of the XLR connectors had to be bored out with a Dremel to accommodate the larger wires of the Z2 cable. I also had to check, double-check, and recheck the polarities of the SDA jack wires to make sure that one speaker's wiring was the reverse of the other. Otherwise, a nasty short circuit condition would result when the SDA cable was plugged in.


Figure 10. Finished SDA 1B XLR cable and jack. There really was no valid reason to put hot glue around the perimeter of the XLR jack plate. The plate fit flush up against the cabinet and was secured by two screws. Furthermore, I used a pound of hot glue over the back of the jack to seal it from inside the speaker cabinet. Sometimes I get carried away.


Figure 11. Finished SDA SRS XLR jack. No hot glue on the outside this time. The jack is placed 20 inches from the bottom of the speaker.


Figure 11. Finished SDA SRS XLR cable and jack.

Conclusion

I do not know which of the Z2's performance parameters contributed the most to the improvements I heard. It may have been one thing or a combination of things. A cable's size, materials, resistance, capacitance, insulation, construction geometry, and termination type all work together to produce its sound characteristics.

It must be noted that the audible improvements noted here were those experienced with my equipment in my rooms. Your results may and probably will differ depending on the cable you select, your electronic equipment and acoustic environment.

[ND13]

You are the "MAN". I tell you, you should make one of those BBs for me. Don't make me beg:D .

[HBombToo]

Nice job and very inspiring.

I have often mused and spoke of doing an interconnect upgrade but it never seemed to spark much attention.

Looks like I'll add that to the ever growing list.

HBomb

[Polk65]

The improvement to soundstage depth intrigues me. This for sure is on my list of things to try.

[jcmccorm]

Raife, thank you once again! Looks like I'm not yet finished with my SDA SRSs. (I've already replaced all of the tweeters and mod'd the crossovers based on your work).

I don't want to start a debate about speaker wire, but, the Monster Z2 Reference speaker wires are pricey. Do you believe that good ol' Home Depot 12ga speaker wire (which I'm currently using to connect the SRS's to my Adcom 5802 amp) would provide the same, or at least part, of the benefits?

Cary

PS. I made a mistake. My rears are using HD wire, my fronts (SRS's) are using 12ga SOund King speaker wire from Parts Express. I am curious about using this same wire for the IC cable.

[DarqueKnight]

Cary,

If you have some cables that you are pleased with, then I say go ahead and try them in this application. I have never used the Sound King or HD wire, but I have read favorable reports on the HD wire on this forum and elsewhere. I would think that any well insulated, larger gauge cable with tight connections would be an improvement over the stock SDA interconnect.

A cable's size, materials, resistance, capacitance, insulation, construction geometry, and termination type all work together to produce its sound characteristics. It would be easier to make a recommendation if I knew which cable performance parameter is contributing the most to the improvements I heard.

[BlueMDPicker]

Raife,

Thanks for yet another excellent SDA article posting.

After hearing the differences in various speaker cables I've had in the mix here, I'm convinced that wire can, and does, make a difference in the sound characteristics (synergy) of an amplification system. Somewhere in time, I'll follow-up with this modification to all my SDAs.

Congratulations on the thought, effort and objectivity you consistently employ.

Mike

[madmax]

As always,
Great writeup! When are you coming out with an SDA adendum to your recent manual??? Put me first in line to receive one.

madmax

[DarqueKnight]

Max,

I have been working on a second edition of the Compendium. I was hoping to be finished this summer, but that is not going to happen. I am now shooting for the end of the year.

Whereas the first Compendium was intended as a quick reference guide for long time SDA enthusiasts, the second edition will be more tutorial in nature. Surprisingly, most of the people who wanted one were first short time owners or people looking to buy their first pair. For those types of owners, the Compendium seemed to raise more questions than it answered.

I do not have an idea of what the final page tally will be, except that it will be larger than the first one.

The price will be far, far less than a pair of quality interconnects.:)

[madmax]

Originally posted by DarqueKnight
The price will be far, far less than a pair of quality interconnects.:)

So, it will be far less than 10 G's... :D

madmax

[DarqueKnight]

Clarification:

The price will be far, far less than a pair of reasonably priced quality interconnects.


Of course, Trump might think $10K for a pair of wires is resonable.:D

[schwarcw]

Great Writeup!

I'm a new SDA, and the compendium would probably be great for me. I bought a used pair of SDA 2s from the original owner about six weeks ago. They were in immaculate condition, and I couldn't turn down the $100 price tag. I didn't know what I was buying and all you great folks have helped educate me about these speakers. Of course the sound from them was the first clue that I had something really special. I am planning to buy the silk tweeters this month. An I've seen bits and pieces about the benefits of a crossover upgrade. Maybe one of you SDA enthusiasts will direct me to the thread with some detailed information about the how and where to get the parts. Thanks again for the information.

Carl

[dorokusai]

Excellent post....makes me wish I posted pictures of my projects :)

[DarqueKnight]

Originally posted by dorokusai
....makes me wish I posted pictures of my projects :)

Well, you should.:)

I hope this will hold me for a long while. I'm tired of smelling solder.

[DarqueKnight]

Originally posted by schwarcw
Maybe one of you SDA enthusiasts will direct me to the thread with some detailed information about the how and where to get the parts.

Do a search on "sda modification".

[dorokusai]

Mark me down for a couple copies of the new SDA bible :)

[DarqueKnight]

Sure. I think it's very considerate of you to get the puppy his own copy this time.;)

[candyliquor35m]

I can't wait to try this. I'll probably rig something using some 10-12 gauge wire and a flat spade for now. I vote this into the Hall of Fame Sticky. Oh wait, we don't have a Hall of Fame Sticky :)

[I-SIG]

Add me to the SDA Bible list as well.

Wes

[dorokusai]

Originally posted by DarqueKnight
Sure. I think it's very considerate of you to get the puppy his own copy this time.;)

Hey, she is a Polk fan, shouldn't she be a Polkie :)

[SDA SRS 1.2]

Count me in for the second edition as well! I keep the first one at work and read it over and over again every so often - makes me look forward to getting home and enjoying those great speakers. Thanks again Raife for such a great Compendium! :)

Robbie

[dcarlson]

Is there anyway I could get the first edition compendium while waiting for the second edition? :)

[DarqueKnight]

dcarlson,

I don't have any copies of the 1st edition left other than my two personal copies, one of which is signed by Matthew Polk and stays in a vault, and the other which is my reference copy.

I used to have stacks of them hidden in a closet until a few months ago. A fellow was selling his SDA's on eBay and posted a picture of the Compendium in his ad. That cleared me out.

[jcmccorm]

Hehehehe. I feel at least partially responsible for that.

I saw the ebay ad also and had to have a copy of Raife's compendium.

I'm glad I got one of the last ones!!

Cary

[dbnh]

I'd be interested in hearing about testing results of one of the above mods from anyone who chose to use VH Audio's 9 AWG star-quad raw wire (Chris VenHaus - great audio guy who has tons of DIY recipes/items, as well as ready-to-go cables, etc. - I swear by his power cords...).

Anyway, the tweaks sound like wonderful ideas to eke a bit more out of my SDA 1-Cs. DarqueKnight, thanks for sharing. Also, for what it's worth, I use Walker SST on my audio gear to include my speakers cables and the SDA interconnect cable pins. I've heard definite improvements with the SST in my system - soundstaging, imaging, detail, etc...

[2-tall]

Do you feel that this interconnect cable would be better than the AI-1 that I am using?I am using a Carver amp that is a common ground.

[DarqueKnight]

If you have a common ground amp, why are you using the AI-1 interface cable?

The answer your question is...maybe.

You might hear some improvement using an SDA interconnect composed only of wire rather than the AI-1 cable which is composed of wire and a transformer.

I have never used an AI-1 cable, but I have read reports that it can cause a slight loss of high frequency detail.

[2-tall]

When I purchased my 3.1TL's the AI-1 cable came with them .There was no other cable included with them.Trying a different cable could be interesting.

[SCompRacer]

I have never used an AI-1 cable, but I have read reports that it can cause a slight loss of high frequency detail.

I had asked Ken about using the AI-1 cable with common ground amps and here is what he said:

"The only thing it could do is add to the source impedance of the SDA circuit path and slightly reduce the level of the SDA corrective signal. Probably, if you were using common ground amplifiers it would be best to use the stock cable, there might be a small increase in the level of the SDA signal produced by the speaker."

I have both but never compared the two.

[BobMcG]

Terrific write-up. Put this longtime SDA'er on the list for a new SDA bible when it's ready.