Soundlab M1 and Alpha-Core cables


Hello Everyone,
My understanding is that Soundlab speakers are high impedance speakers, and that is why they are hard to drive. Alternatively, my understanding is that Alpha-Core MI and AG series speaker cables are low impedance and high capacitance. Would this mean that these cables would be a good match electrically with the Soundlabs? Thanks in advance for your thoughts.

Regards,
Dennis

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Sean -

I'm a little curious about the comments you made on output impedance of the amp and impedance ratings of the speaker cables and speaker. I use AC MI-2 and from what I can tell from specs published on the website they are 2.5 ohms impedance. My speakers are Spendor 1/2e rated at 8ohms nominal impedance (they dip but stay pretty flat overall). I have not perceived any issues with my amp, which is custom built and while I know the input impedance, sensitivity and gain, I don't know the output impedance. Ideally if I have the AC MI-2 specs correct what should be a good output impedance range for my amp?
Unsound: The Reference speaker cable is stacked ala Goertz and the Signature is placed side by side ala Nordost. I guess that David is trying to play both sides of the street simultaneously. The end result is that these two cables would measure and perform quite differently, even though they might use extremely similar materials. The difference in geometry i.e. stacked or side by side makes for a huge difference electrically. Stacked gives you a MUCH lower impedance( what we want ) whereas side by side will put you up over 80+ ohms ( at least ).

For the longest time, i thought that the Magnan's were "side by side", but when i looked at the info on the Reference last night, it stated "stacked". As such, i chalked it up to memory failure and "ass-u-me'd" that the Signature's were built like this too. They aren't and i'm glad that you pointed this out. As a point of reference, i've used and liked some of Magnan's interconnects, but never their speaker cables.

As to their terminations, i too think that they are the weak point of the design. It almost looks like they are using a "standard" solid or stranded lead attached to the foils. To my mind, this pretty much negates many of the benefits of the foil. On top of that, there's got to be a very measurable impedance bump in this region, creating inconsistencies in the signal path.

As to the AP cabling, they've used two different geometries over the years. Their copper cable used one design geometry and their silver cabling used another. I was involved in several different MAJOR debates about this cabling. My question to proponents of this cabling, and the manufacturer of this cabling, was that if one design is electrically superior, which is what they stated was demonstrated in their computer modeling, why would they use anything but that geometry regardless of the type of conductor used? The fact that they talk so much about skin effect yet neglect to mention "strand jumping" was also a HUGE falling point with me. After hearing these cables, i could not get rid of them fast enough...

As to your idea about using hollow cables and configuring them into a twisted pair, that would be an inconsistent mess. Due to the oval shape and twisting them, you would run into massive differences in contact area between the conductors. This would result in an ever changing impedance and inconsistent Td ( Time delay ) through the cabling. One would hear this as a smeared sound with a lack of focus and solidity. Compared to many cables though, it would be no better or worse.

Clio09: Most any Solid State ( SS ) amp should be fine here. Output impedance for most SS amps is quite low and are therefore quite suitable for use with Goertz flat series of speaker cabling. On the other hand, many tubed amps have an output impedance that is anywhere from one to a dozen ohms or so, introducing further variations into the equation. Using a low impedance cable like that of the Goertz design may cause poorer sonics rather than improvements. This would be due to the lack of "buffering" that most higher impedance speaker cables would present as part of the load that the amp sees. The less "buffering" that a high output impedance amp sees, the less linear and consistent the sonics will be.

As a side note, Nelson Pass ( and a select few others ) are making special amps with VERY high output impedances on purpose. The lack of linearity is being purposely taken advantage of for use with other non-linear devices i.e. limited bandwidth full range speakers utilizing a single driver. The lack of "buffer" or "damping" introduces a bass peak, which helps to balance out the sound of these otherwise "lean" sounding speakers. Kind of like using two negatives and trying to make a positive. Only problem is, the results can vary SOOOOO drastically, that a LOT of trial and error will be required in order to obtain the desired results. It is my opinion to start off with the highest level of consistency possible and build from there. Sean
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Sean, thank you for your reply. At the risk of appearing argumentative, wouldn't it be possible to twist these tubes in such a manner so that the same side of each coductor would maintain contact? The only reason I suggest this arrangement is because Alpha-core suggests that "purling" has some advantages. Perhaps we could even abandon the idea of twisting. Would hollow oval tubes have an advantage over solid oval conductors?
Sean,

Thanks for the clarification. I have rather enjoyed the AC MI-2 cables over the last year or so. However, I have been interested in doing A/B comparisons against the AC MI-2 just for the heck of it. The Magnan's were on the list, but now I think I'm going to give the Supra Swords a listen instead.
Unsound: If you look at how Alpha does their "purling", the conductors are "stacked together" and THEN twisted. As such, their impedance remains consistent and they are not configured as a standard "twisted pair" configuration. Maybe i misinterpreted what you were saying i.e. the twisted pair configuration and ended up putting words in your mouth, but that's what came to mind. It would be hard to keep "hollow" cables "stacked together" when using some type of core, hence my "logical deduction".

Clio09: As far as the Magnan's go, they might well be worth a shot. The reference might have some slight theoretical advantages over the Goertz and it would be an interesting comparison. The foil would have even less skin effect than the "strapping" that Goertz uses, although i see the potential for a far less consistent impedance in that specific configuration. That is, the Goertz conductors tend to cling together relatively tightly in the way that they are bound. I don't think that the Magnan's are built in similar fashion.

On top of that, it would be easier for the foil to kink, bend, crinkle and / or seperate from one another, potentially introducing other electrical side effects. All of this is besides the previously discussed comments pertaining to how the foils themselves are terminated.

As far as speaker cables go, there's a comparison that i wanted to make for quite some time. I purchased the necessary parts quite some time ago, but never got around to it. Once i could put these cables together, the end result would be a conductor that was nearly equivalent to the Goertz MI-2's in gauge with a similar, but slightly higher nominal impedance. Due to the materials used, skin effect should be slightly reduced and treble speed may be slightly increased.

This is all theory though, so until i can get around to doing this and performing the associated tests, it's all a moot point. As we all know, there can sometimes be major divurgences between theory and reality : ) Sean
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PS... When making comparisons, try not to confuse "different" for "better". It's an easy thing to do because of the "newness factor" : )