Alpha-core advise?


I recently tried some Alpha-core MI 2 speaker cable and was quite impressed. When I made inquiries at Alpha-core, two different engineers gave me conflicting advise. Perhaps some one here can straighten me out. My curent system uses a Threshold S/500 series II driving Thiel 3.5's. The Threshold according to Jon Soderberg who used to work for Threshold is capable of doubling down. The Threshold is rated as 250 Watts per channel. The Thiels are rated as 4 Ohms nominal and 4 Ohms minimum. Independent tests show this to be rather accurate (an amazingly flat load) with one peak at about 33 Hz to about 8 Ohms. Ergo the amp may be pushing up to 500 Watts per channel. It was originally suggested by Alpha-core that I use a pair of MI 2's for my requested 8' run. They latter suggested that I run two pairs (not a traditional bi-wire situation). Unfortunately the speakers binding posts couldn't accept more than one set of the attached silver spades. When I called back, a different engineer suggested MI 3's. I'm a bit confused by the "characteristic impedance" issue. If one were to double up runs of these speaker cables, would the "characteristic impedance" half?, remain the same?, double? or something else? One advantage to this speaker cable line is that they can be made in such a way that they could have integral "spades" rather than added on ones. The advantage of the MI 3's over the MI 2's, due to greater width would be increased surface area if they were terminated in this fashion. The advantage of using double runs of MI 2's would be decreased cost and perhaps (and this depends on the answer to the previous question) better impedance matching. The Alpha-core web site suggests that this design needs little break in. Would these cables benefit from the use of a cable cooker? BTW, I am now considering using 3 meter to 10' runs. What's a boy to do?
unsound
My MI-2 Veracity cables broke in just nicely on their own over a weekend. No cable cooking required. I Have had them over a year now and love them.

As to your other dilemma I plead ignorance but am curious as to the outcome.
very nice cables
I have no doubt that the Threshold amp can deliver 500W, but that does not mean the speakers are demading all of that to require more than the MI2 cables can deliver. I personally think your cables should be sufficient and you state that you like the sound. The techs at AlphaCorps are not in conflict by saying that if you do not want to use doubled MI2s then you can use the larger MI3. And yes the impedance halves in parallel. You may benefit by looking up an old post from Sean about a Zoebel filter at your speaker inputs when using Alpha corps cables. I am very happy with the MI1 cables and this filter on a lower powered system than yours.
When I purchase my MI-2s they came with the Zoebel network already integrated into the design. No extra work on my part. It doesn't hurt to have it on their even if you don't need it from what I was told by Alpha Core.
Thank you for all the replies. I did use supplied external Zoebels when I tried these cables. Oldears, the techs (I was told they were engineers) actually did conflict. The first one said by using 2 pairs of MI 2's I would be doubling the "characteristic impedance" of 2.5 Ohms to 5 Ohms and there by creating a closer match to the speaker load. He also said that 4 lengths on the MI 1's would create a perfect 4 Ohm load, but, the binding posts wouldn't accomodate that. The second engineer said the opposite and that doubling up the lengths would halve the "characteristic impedance". As for the power output of the amplifier, let me say that it is used in a fairly large room (14' ceiling peak) and that the speakers use an active equalizer that boosts the signal below 70 Hz by up to 12 dB's. I would think that would put quite a demand on the amp. Alpha-core seems to have a funny pricing system, 2 lengths of MI 2's cost less than 1 length of MI 3's, yet they claim that the MI 3's have the perfomance of 2 MI 2's. Alpha-core claims that matching the impedance load is what makes their product special. To be fair, they also claim that absolute matching is unnecessary. From what I am led to believe equivilent runs of MI 2's would offer a closer impedance match at a lower price, the MI 3's would offer a less ideal impedance match, better/ bass control and more surface contact with "integral spades" at a greater cost. Any thoughts?
I'm running MI1 biwires from the 4 Ohm tap on a Music Reference RM-200 to VMPS RM-30s.

Here's my understanding of Alpha-Core's MI offerings:

MI3s offer twice the material (i.e., raw copper by weight) and half the resistance of MI2's, which in turn offer twice material and half the resistance of MI1's. Specifically, the equivalent gauge of MI3s, MI2s, and MI1 is approximately 7 AWG, 10 AWG, and 13 AWG respectively. This corresponds to a resistance of 0.0011, 0.0022, and 0.0044 Ohms/ft respectively (http://www.alphacore.com/mispeaker.html).

I thought I recalled a time when the cost of bare, unterminated wire scaled exactly with material (i.e., cost of unterminated MI3's = 2 * MI2's = 4* MI1s), but according to http://www.alphacore.com/shop/Speaker_CablesznCopper.html this is not true today, and indeed you do get a bit of a "bulk" discount as you move up the scale.

The resistance measures are relatively unimportant. Any system will overcome the difference between 0.0011 Ohms/ft and 0.0044 Ohms/ft with only the slightest adjustment to the volume. But impedance is another story.

Resistance is strictly an inhibition to electron flow for DC: i.e., a zero frequency, infinite wavelength signal. Once we introduce alternating current--which is what amps use to drive speakers--then capacitive and inductive reactance interact to also impede current flow. The (complex) sum of resistance, inductance, and capacitance is called impedance. It is the net inhibition to AC flow. Inductance can be thought of as an inhibition to a *change* in current (not simply an amount, or amplitude of current) caused by the generation of a magnetic field. Because music as encoded in oscillating electrical signals is highly dynamic (lots of change), excessive inductance per se--without some other reason for its presence--cannot be considered a good thing. Inductance acts as a low-pass filter, so the closer you get to DC, the better the current flow at the frequency, while the higher the frequency, the greater the inhibition.

Alpha-core's claim to fame is that by sandwiching the (+) and (-) wires so tightly together, they greatly reduce inductance (at the cost of increasing capacitance), to the net effect of low, final impedance numbers. Specifically, they claim a characteristic impedance of ~1.7 Ohms for MI3, 2.5 Ohms MI2, and 4 Ohms for MI1 (http://www.alphacore.com/mispeaker.html). Additionally, they do this in a very smart way: by sandwiching the strands so closely together, the mutual inductance that is generated in one wire as a direct result of oscillating current within it, is canceled almost exactly by the opposite effect in the other wire. So they get low impedance numbers by lowering net inductance--a smart quantity to lower for audio applications. Some folks claim that wires that tend to maximize inductance (the opposite of Alpha-Core's offerings) roll the highs (which may be good or not so good, depending on what's coming out of your amp).

Lower inductance comes at the cost of increasing capacitance. Because the (+) and (-) strands are so closely sandwiched together, it is easier for current to cross the insulation between the strands. Capacitance acts as a high-pass filter, so it is high frequencies that are "shorting" across the wire. But the capacitance numbers are in the pico-Farads/ft, so only spurious frequencies way off the audio scale (and beyond the capacity of most amps to generate) would be affected. So you are kinda' getting something (low inductance) for nothing (high capacitance): a good trade. Some amps may pathologically oscillate when presented with a high capacitance load, so the simple solution is to short the wires with a capacitor and a resistor (called a Zobel network), so the HF energy is simply dissipated as heat in the resistor, leaving the amp unaffected.

What does all this mean? Imagine, if you will, a complicated Rube-Goldberg contraption of pipes of differing sizes, all connected in funny ways and filled with water. This contraption is our analogy to your system as it runs from the wall to your source, pre-amp, amp, and finally speakers. Now start an oscillation at one end by tapping (e.g., at 60 Hz), and the goal is that via this convolution of pressures and relays and valves and so forth, a complicated oscillation of waves--an amplified mimic of the musical source--will come out the other end. With this analogy you can see that when you join a wide pipe to a narrow pipe, or vice versa, as the wave hits the junction it will create reflective waves back down the stream, which in turn will interact and (slightly, or not so slightly) corrupt the signal. This is an example of an impedance mis-match, and with electricity there is the same, analogous phenomenon. When you change impedance, waves are generated on the line. This is one reason why digital cables from a transport to a DAC can make a difference. Even though virtually all transports and all cables will send S/PDIF signals bit-perfect, minor anomalies caused by impedance mismatches generate jitter on the line, and affect the signal (specifically, it's timing). So, impedance matching has some relevancy to audio, and Alpha-Core's claim is that they do a better job than most in minimizing impedance mismatches between the amp the speakers, while at the same time lowering inductance.

How is this standardized? If you take a piece of speaker wire (w/ (+) and (-) strands), and don't hook it up to either the amp or the speaker, but simply measure the impedance between the strands it will measure essentially infinite. That is, the insulation between the strands creates a very high inhibition--which is good, because anything measurable would be a short. But in reality the inhibition is not infinite. There is some material separating the (+) and (-) strands, even if it is only air or an almost perfect vacuum. And indeed, there is a slight crossing of electrons between strands--that is, there is both a voltage and a current. An indication of the insulation material's propensity to carry--or inhibit--current is called the dielectric. The longer the cable, the more insulation, or opportunity, there is for electrons to cross. If we took an infinite length of cable, and then asked "Given this infinite length, what is the net inhibition to election flow across the insulation?" the answer would be the characteristic impedance. For RCA interconnects, this is historically 75 Ohms. For speaker cable there is no standard, so Alpha-Core says, "Well, let's make it close to the speaker's average band-wide impedance in a effort to minimize impedance mismatch." (Quotes are mine, not theirs).

At the end of the day, I think most systems would be challenged to uncover a difference between 1.7 Ohms characteristic impedance, 2.5 Ohms, and 4 Ohms--but, no doubt, some will show a difference with different wires. But do this part on listening—I don’t think we can rationalize/intuit that 2, or 4, or 5 Ohms will be better just because one number is closer to a speaker’s average impedance rating: it is better to compare Alpha-Core's offerings as a whole to cables that are in the 100+ Ohms category. I’m sure MI1’s would sound great on some 8 Ohm speakers. Alpha-Core gives a bit of a guide to choosing cables based on characteristic impedance here: http://www.alphacore.com/mifaq.html#select.

Hope this helps
1) The nominal impedance of most any product known to man will vary as frequency is altered. This includes speakers, the output impedance of the amp, speaker cables, etc... As such, the key here is to use components that are "reasonably well matched" in terms of impedance and are capable of delivering the required amount of sustained voltage and current into those impedances without strain. It would be impossible to match impedances in a precise manner as far as the amplifier / speaker cable / speaker is concerned.

2) MI3's present a VERY low nominal impedance to an amplifier. While this can allow greater power transfer to occur, it can also "load down" the amplifier during very demanding passages with difficult speaker loads. On top of that, very short runs of MI3 connected to a reactive speaker can introduce increased non-linearities into the system. This is due to the higher than average amount of reflected EMF that the amp would see from such a low loss / low impedance speaker cable "modulating" the output of the amplifier. In effect, a slightly higher impedance ( like that of the MI2's ) can provide a bit of a "buffer" and add stability to the circuit.

3) Running multiple cables in parallel to the same set of binding posts would actually introduce erratic impedances into the amplifier / speaker equation. This is due to the variance in both spacing and geometry of the paralleled conductors, which are otherwise controlled through design considerations at the time of manufacturing of a single cable run. As such, some of the benefits of matching the nominal impedance of the cables to that of the speaker may be negated. In this respect, more is not always better, especially when one selects an optimal combination to begin with.

4) I would only recommend running MI3's for use on longer runs with VERY sturdy amps ( which are few and far between ). The MI3's lower nominal impedance, very heavy gauge conductors ( 7 gauge ) and minimal high frequency losses will tend to reduce the otherwise greater losses associated with these longer runs. Due to the higher levels of capacitance of these cables, which would be compounded by using longer than normal lengths, may require greater attention to detail in terms of the zobel's used and where they are placed in the circuit.

5) Goertz flat speaker cables require minimal break-in as compared to the mass majority of other speaker cables. This is due to both their geometry and materials used.

6) I would stick with a single run of MI2's so long as length is kept reasonable. The length that you are working with ( appr 10' ) should be fine for this application.

7) As previously mentioned, these cables provide a very neutral signal path joining the amp with the speakers. Whether or not you like what these cables bring to your system will be more a matter of how good of a job you did in selecting a suitable amp to drive your speakers instead of how much of a personal preference you have for other cabling and the colourations that they bring with them due to inferior design and materials. As such, be forewarned that better / more neutral cabling may not result in "better sound" or "sound that is more to my personal preference". If it sounds like crap with this cabling, don't blame the cabling, as the cabling is simply allowing you to hear what your system really sounds like.

Hope this helps and answers some of your questions. Sean
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Thanks Sean. I was hoping you might respond. The MI 2's were an improvement with the 2 different amps and 2 different speakers I tried them with. Interestingly the greatest improvement was with the smaller less expensive amp and to the smaller less expensive speakers. I miss having them here already. I think that the Thiels and the 3.5's in particular must be amongst the least "reactive" speakers offered. Wouldn't the use of the Zoebles compensate for the greater potential for reflected EMF in the MI3's? It seems pretty clear that your suggesting the MI 2's over the MI 3's for my application. Am I correct in assuming that you don't believe the Threshold S/500 II qualifies as a "VERY sturdy amp"? The idea of using integral spades has some appeal. Obviously the MI 3 lends itself to this application better than the MI 2. In the past you have recommended the use of Alpha-core silver spades, any thoughts on using the Alpha-cores "au-natural"? If so, what would you suggest vis-a-vis the MI 2 vs. the MI3? You mention that the "Goertz flat speaker cables require minimal break-in as compared to the mass majority of speaker cables. This is due to both their geometry and materials used." You have also endorsed the use of a cable cooker in past posts. Are you suggesting that these cables may be exempt from the advantages of using a cooker? BTW, Alpha-core seems to be shying away from making claims about the use of teflon in their latest MI 2 & 3 offerings. Any thoughts on the Alpha-core pricing structure? Seems a bit strange to me. Out side vendors seem to be able to provide more competitive pricing than buying direct as well. FWIW, I did manage to snap off the leads of one of the supplied Zoebels when tightening down on the speaker's binding posts. In the past you have suggested that one could improve upon the supplied design. How would I go about determining how to produce these for my application?
I recall Nelson Pass commenting that the capacitance of the ribbon cables could cause some amplifiers to oscillate. I believe he was refering to his older T-hold models of which yours is one.

A quick note to Nelson or Wayne at Pass Labs should give you a quick answer. It's worth asking to prevent damage to the amp.

Better safe than sorry,

Loon
Rabelais, thank you very much. You have confirmed what I suspected about "characterisic impedance". Knowing is so much better! With regard to "bulk discount" it actually appears to be inverted; as you go up the line you pay a HIGHER rate! Very odd. Since I've already accepted the Alpha-core's as being superior (at least to my ears, in my system, at this time) to other manufacturers offerings, its come down to deciding between alpha-core's products. The scale that Alpha-core offers on their web site re: application in systems seems to be a rather general guide line rather than a strict requirement. Sean's opinion (for which I have great respect) seems to at the very least bear this out. The fact that the difference in price more than doubles is worthy of consideration too. IMHO, the MI 2's appear to be quite a bargain in comparison to just about anything else I've heard. The MI 3's, well thats a different ball of wax. I can't help but wonder if the market segment being pursued here may be more responsible for the elevated price more than the cost of materials.
Loontoon, thank you for the heads up. I believe the use of the afore mentioned Zoebles resolves the amplifier oscillation issue.
Unsound, a little late to the thread, I use MI 2's on thiel 3.6's with Mcintosh mono's - 500 watts per side. I get great sound and don't see the need for a larger guage cable like the MI 3's. Very coherent top to bottom and the amps run cool. Just my nontechnical 2 cents...
Right on, Unsound. You're right about the price jump from MI2 to MI3, but strangely, MI2 < 2 * MI1; e.g.

8' MI1 = $99 + termination;
8' MI2 = $172 + termination;
8' MI3 = $424 + termination

Anyway. Re "Sean's opinion (for which I have great respect)... ." Ditto.

My guess is that MI2's will suit your situation fine, but they have a good team at Alpha-Core and offer a money-back guarantee if you order direct, so you may approach them with the proposition that you'd like to order a set of MI2s and one of MI3s--with every intention of returning one--and see if they'll go for that. Then you can make a decision where it matters most: in your listening room.

Best to you
They went for that deal when I purchased from them. I tried the MI-2 and Python bi-wire and kept the MI-2. Very nice folks to deal with and prompt refund on the returned cables.
"Interestingly the greatest improvement was with the smaller less expensive amp and to the smaller less expensive speakers."

Gear that is less robust will always respond better to improved signal transfer characteristics. "Sturdier" gear has more muscle and can more overcome / deal with some of the more common problems that we run into. As such, i'm not surprised that less expensive gear "woke up" in more noticeable fashion.

"I miss having them here already."

That's easy to fix : )

"Wouldn't the use of the Zoebles compensate for the greater potential for reflected EMF in the MI3's?"

Zobel's have nothing to do with signals within the audible passband. In effect, they are kind of like a "high pass crossover" at ultrasonic frequencies. That is, the value of the capacitor selects what frequencies are allowed to enter into the resistor to complete that portion of the circuit. Since the frequencies that are affected are well beyond audibility, the power transfer characteristics within the audible passband aren't hampered or affected. The only thing that the Zobel does ( in this case ) is to present the amplifier with a suitable load at VERY high frequencies, which is what helps to keep the amp stable and negate the potential for oscillation. As such, the reactance / reflected EMF from the speaker remains the same regardless of whether or not you have a Zobel hooked up.

"Am I correct in assuming that you don't believe the Threshold S/500 II qualifies as a "VERY sturdy amp"?"

I do think that this is a sturdy amp, but i also believe that there are amps out there that are "sturdier". Like anything else, there are most certainly ways to improve upon most any product known to man. Some of this will boil down to empirical fact, some of it to personal preference / voicing of the equipment.

"The idea of using integral spades has some appeal. Obviously the MI 3 lends itself to this application better than the MI 2. In the past you have recommended the use of Alpha-core silver spades, any thoughts on using the Alpha-cores "au-natural"? If so, what would you suggest vis-a-vis the MI 2 vs. the MI3?"

The fewer the connections in a signal path, the better off you are. Having said that, my concerns about reliability and potential damage are what prompt me to recommend the silver spades over a bare connection. This becomes more of a potential for problems as one does more maintenance / removal & reconnection of the cables at the points of termination. Believe me, i have seen some EXTREMELY mangled Goertz cabling in attempts to do exactly what you ask about doing.

As a side note, the bare Copper will tend to corrode in a negative manner whereas the oxidized Silver still remains HIGHLY conductive. In fact, Silver Oxide ( that nasty black crust ) is more conductive than Copper is at its' best. As such, you will have to perform more maintenance on bare Copper connections than you would with the Silver spades.

"You mention that the "Goertz flat speaker cables require minimal break-in as compared to the mass majority of speaker cables. This is due to both their geometry and materials used." You have also endorsed the use of a cable cooker in past posts. Are you suggesting that these cables may be exempt from the advantages of using a cooker?"

"Cable cooking" has more to do with skin effect and conditioning of the dielectric than anything else. Due to the fact that the Goertz design is ALL "skin" and uses minimal dielectric, the benefits of using some type of "burner" are largely negated. On top of that, the lower impedance design encourages greater power transfer, so the amp will "load up" into the cabling and speakers better. This increased level of output helps to condition the cabling in rapid fashion.

"BTW, Alpha-core seems to be shying away from making claims about the use of teflon in their latest MI 2 & 3 offerings."

They still produce their older version along with offering the newer Teflon insulated version as far as i know. Given that the Copper conductors already have a very thin layer of dielectric applied directly to them, the difference between the "old school" Goertz insulation and the newer Teflon models may not be as great of a difference as one might expect. I haven't any personal experience with the newer Teflon models, so i can't say. The one time that i would highly recommend the Teflon models over older models is if one lives in an extremely humid environment. The older dielectric used is more sensitive to moisture whereas the Teflon isn't.

Any thoughts on the Alpha-core pricing structure? Seems a bit strange to me. Out side vendors seem to be able to provide more competitive pricing than buying direct as well.

Price structure on most products is based upon manufacturing and distribution costs. Just because something uses 2x, 4x, 8x, etc... the amount of materials to produce, doesn't mean that the price to actually manufacture that product is 2x, 4x, 8x, etc... that of the original. This has to do more with increased complexity of handling( more material may require more labour as it is harder to work with ), increased cost of packaging, shipping costs, etc...

On top of that, "charging what the market will bear" also enters into the equation. As we all know, many "high enders" don't think that they are getting something special unless it costs more. Since Goertz is "reasonably priced" compared to many other brands, they probably jacked up their top of the line cable a bit in order to offer the higher level of prestige that price brings with it. As previously mentioned though, there are times where a "top of the line" cable may not be best for a given installation, so "more is better" doesn't always apply.

As to retailers offering a better deal on the cable vs buying direct, Goetz is simply charging list price for their cables. This protects their dealers, which can offer as big or little of a discount as they see fit. Whether or not a dealer will offer the same type of trial period may be a bit of a factor in the price differences that could exist in such a situation.

"FWIW, I did manage to snap off the leads of one of the supplied Zoebels when tightening down on the speaker's binding posts. In the past you have suggested that one could improve upon the supplied design. How would I go about determining how to produce these for my application?"

Simply purchase the proper parts in the corresponding values, attach their legs together in some form of permanent fashion and attach them to the speaker terminals. I use MUCH heavier and higher grade parts than what is needed, but then again, i tend to go overkill on most things. I also covered the parts in shrink wrap so as to avoid the potential for broken connections and / or shorting out at the binding posts.

One could actually attach some form of spades to the legs of the Zobel so as to avoid crimping or cutting off the leg at the point of connection. I used banana plugs on mine, which allows me to tighten down the posts on the spades and then attach the Zobel's by inserting them into the holes in the binding posts. No interference between the speaker cable / binding post connection and the Zobel can still do the job it is supposed to.

Hope this helps. Glad that you found the Pass designed products / Goertz combo to be as synergistic as i have.

Clio09: The Python's have WAY more dielectric and are therefore a lower grade cable. There are also quite a few electrical ( impedance, velocity of propogation, etc ) variables involved with the Python's, depending on how they are terminated / geometrically configured. More conductors also means more connections with increased potential for differences in signals. I'm not surprised that you picked what you did as the Python type of design came about more from trying to market a more conventional looking cable than an actual product improvement design innovation. Sean
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Thank you all for your responses. I just recieved an 8' pair of MI 2's with silver spades from a fellow Audiogon member. They sound even better than I remember the loaners sounding. The ones I just purchased sound a bit warmer than I remember the original ones sounding. This may also be due to a recent change in line stages. Actually more like the new line stage getting a chance to settle in. Alpha-core was kind enough to shoot me an e-mail advising me that 10' was about the maximum length they would recommend for the MI 2's in my system. Should a pair of MI 3's avail themselves, I might give them a try. These Alpha-core speaker cables are hands down the best I've ever tried. I never thought cables could make this much of an improvement. Any thoughts on Alpha-core interconnects?