Alpha-Core Goertz speaker cables


My curiosity is tickled by these speaker cables and the idea that low cable inductance is the desired electrical characteristic for speaker cables, after low resistance. I find no discussion of this in the past topics and few systems show these speaker cables. What are your thoughts on this type of cable and its advantages and disadvantages? Any current users of the M1 or M2? I am currently using Wyred 4 Sound Sx-500 monos with short anti-cables and Von Schweikert VR-4JRs. Thanks in advance.
tgrisham

Showing 4 responses by almarg

A lot of people have reported excellent results with them, but I'd be cautious, as Elizabeth suggested. Their ultra-low inductance is achieved at the expense of ultra-high capacitance, and if a Zobel network is not used that can cause some amplifiers to oscillate, and possibly fry. Although since you are using monoblock amps the relatively short cable lengths will reduce that possibility, since the total capacitance of the cable is proportional to length.

The extent to which the ultra-low inductance will make a difference (as opposed to being overkill) depends on the impedance of the speakers at high frequencies. The lower that impedance, the greater the likelihood of there being a difference (which is not to say that the difference will necessarily be for the better, subjectively). But as with most dynamic speakers (as opposed to electrostatics, for instance), I suspect that the impedance of your speakers rises considerably, rather than falls, at upper treble and ultrasonic frequencies.

The combination of ultra-low inductance and ultra-high capacitance also results in the cable having ultra-low Characteristic Impedance, about which the Goertz website says as follows:
The characteristic impedance of the Goertz MI cables in the order of 2 to 4 ohms closely matches the impedance of loudspeakers. Almost all other speaker cables have characteristic impedance ranging from 50 to 200 ohms, a mismatch which causes distortion due to signal reflections. Impedance matching primarily improves the clarity of the highs and upper mid-range, but many users have also experienced improvements in the lower mid-range. The cause seems to be that signal reflections caused by impedance mismatch enter the feedback loop of many amplifiers and disturb their ability to reproduce faithfully even lower frequency signals.
IMO that makes no sense, at least in the context of a dynamic speaker. The reflection effects that it refers to will only occur at RF frequencies, and possibly to a small degree at ultrasonic frequencies. At those frequencies the impedance of a dynamic speaker will be much higher than the 4 or 8 ohm impedance it may have at audible frequencies, and at those frequencies the impedance of the speaker therefore will not come close to being a good match to the characteristic impedance of the cable. Very conceivably it could even be a worse match than would exist between the speaker impedance at those frequencies and the characteristic impedance of a cable having ordinary parameters.

Regards,
-- Al
A p.s. to my previous post. In addition to capacitance being proportional to length, as I had mentioned, inductance is also proportional to length (as is resistance, for that matter). The relatively short length that you require will reduce whatever difference having low inductance per unit length might make.

Regards,
-- Al
Gkp, without knowing any of the details of your system and setup, particularly what amplifier you are using and how long the cables are, I'd have to say that without a Zobel it would be a significant concern.

The MI3, along with the AG3, have the highest capacitance of any of the Goertz cables, at 1500 pf/foot. From the perspective of the amplifier, using a biwire pair will double that.

Factors that would increase the likelihood of a problem are long cable length, the amplifier being solid state, the amplifier having wide bandwidth, and the amplifier using relatively large amounts of feedback.

Regards,
-- Al
Gkp, if it were a solid state amp, with 8 feet of cable being required, I would definitely recommend against using a pair of biwired MI3's (without a Zobel, at least). I couldn't find detailed specs on the Debut Mk1 (particularly bandwidth and how much feedback position 6 corresponds to), but FWIW my instinct is that since it is tube-based you would probably be ok, but nevertheless the risk isn't worth it.

I suspect that the chances of oscillation and/or damage occurring would be small, but even so putting 24,000 pf of capacitance across each of the amplifier outputs doesn't figure to be helpful sonically.
At this point I will probably pass on the extra set of cables and just get better jumpers.
Sounds like a plan!

Regards,
-- Al