Thin speaker cable (damping factor)

[doctorcilantro]

I'm testing some speaker wire in my setup:


Quicksilver Mini-Mites 25w/channel

Klipsch RF-7 98db/1w


Solid silver cable 28awg 4feet which is total of + & - leg on one amp/speaker.


Using this calculator (www.tnt-audio.com/clinica/wirecalculator.xls) I'm getting very different damping factors when I
plugin in the above (with 4ohm & 3ohm speaker & amplifier
resistance) as compared to a smaller gauge wire e.g. 16awg. Damping
Factor works out to about 2 with 1db loss whereas the 16awg provides df
of 37 and loss of only .09db.


"Transistors vs Tubes:

In general, 'solid state' amplifiers (transistor amplifiers) tend
to have a higher damping factor than tube amplifiers. Transistor
amplifiers drive the speakers directly and may have a damping factor
greater than 200. Most tube amplifiers drive the speakers through a
large transformer which tends to lower the damping factor of the
amplifier. The damping factor of top notch tube amplifiers may be as
low as 20. Please understand that the lower DF is NOT an indication of
the quality of the amplifier or the sound quality that you will get
from it. Low DF amplifiers can sound really good, easily as good as
amps with higher DFs.

The damping factor indicates the ability of an
amplifier to resist a change in it's output signal. If an amplifier has
a very low damping factor, the speaker load (or any load - like a
resistive dummy load) can cause the output to differ (possibly audibly)
from what it's intended to be. For virtually every amplifier made, the
damping factor is easily high enough to prevent audible changes in the
output signal. Some people say a DF (Damping Factor) of 200 is the
minimum acceptable DF. Others say it's 100. there are even those that
say a DF of 50 is OK. I've tried inserting a series resistor with
speakers and could hear no audible difference at a DF of 50. Around a
DF of ~25, I started to hear a difference with 'some' speakers. At
around a DF of 10, the difference was significant enough to be heard
with virtually every speaker. You may think it always sounded worse
with a low DF. Well, not always. Some speakers (mostly high frequency
speakers) actually started to sound a little better (probably from a
change in the frequency response which was due to its impedance curve).
Of course, some speakers sounded worse with the low DF. In virtually
all cases, the change in sound quality was a 'softer' sound. For very
low DFs, the punchy bass was significantly reduced but the bass sounded
smoother (which may or may not be a good thing - depending on your
taste in music). Now, I'm not saying that the 'smoother' or 'softer'
sound was better (because the change in sound IS a type of distortion).
I'm just trying to let you know how the sound changed with the low
(extremely low) damping factor. "

from http://www.bcae1.com/dampfact.htm

I'm in the process of putting spades on my set of CC89259 and the above 4 foot runs of solid silver.

any thoughts on this?

Jon

[garyrc]

I believe the classic McIntosh tube amps of the 1950s and early 1960s had a damping factor of about 12. They sounded great. At the time, McIntosh had an ad that read: "When will solid state amplifiers sound as good as tubes? When McIntosh makes them!" Some consumers thought McIntosh failed to keep their promise in their first generation of solid state amps -- they were quite good, but not as warm and "lush" as, say, the McIntosh 275 tube amp. Wally Heider recording studio in San Francisco (one of the best) kept their McIntosh tube amps (275s) through at least 1974, in at least the control room I visited. The McIntosh solid state amps had a higher damping factor, though.

In the '60s, one of JBL's engineers published an article that said that there was such a thing as too high a damping factor. His name may, or may not, have been something like George Augspurger (a real guess at the spelling!).

[Duke Spinner]

Augenspurger .

and, no ..

there is no such thing assa too high DF ..

because it degrades laughably, onece you hook a voice coil to it

[Islander]

I've never noticed an audible difference in damping factor, but there's a very noticeable difference in transient sounds with different gauges of speaker cable. Drumbeats and handclaps sound markedly more realistic with bigger cable.

[Guest " "]

my opinion.....A resistor would not be the best way to do this...the resistor adds distortion....the best approach would be to use an autoformer....an autoformer serves to change the impedance while reducing distortion....cost penalty is more power consumption as impedance goes up...but if you have the power to spare...an impedance change from 1.5X to 2X would be the compare point....the autoformers I use for this are the size of a compact disk and have the same stepping as the T2A autoformer.

[doctorcilantro]

I have more reading to do on the three variables affecting speaker wire, but my main point here is that using wire gauge length vs. resistance charts one could arrive at using either large or small gauge depending on length. These kind of charts are commonly referenced as the only point, or variable, that needs to be considered.

Two schools of thought:

"There is some debate about which gauge of wire is optimal. The late Harvey "Gizmo" Rosenberg used 18 AWG (American Wire Gauge) in his personal system at The Triode Guild and mentioned that Dan D'Agostino of Krell preferred the heavier 16 gauge wire. (See Gizmo's article in Positive Feedback for more on this subject.)

Allen Wright, author of The SuperCables CookBook,
is a vocal advocate of using the thinnest wire possible, such as 30 AWG
(or smaller) for interconnects and a thin ribbon of silver foil, 25 mm
wide x 0.05 mm thick, for speaker cables. Do the math and you'll find
that the latter actually translates into a cross section equivalent to
16 gauge, as well, albeit with a much larger surface area than round
wire."

There is something very different going on with the speaker cables in terms of the value of DF. I'm curious how the amps and speakers one uses fit in when combined with high or low DF (due to speaker cable choice).

Jon

[doctorcilantro]

Turns out I have 22awg wire. By 6 feet max at 4ohms, does that mean to include the + & - runs? If you take a look at the TNT calculator I linked to , they make that stipulation. Furerthemonre, I have never seen any chart like the one here make such a caveat. So I can go to CC89259 speaker cable which has an effective 13.5 awg, lower resistance, but have a MUCH different DF.

Wire Size	2 ohm load	4 ohm load	6 ohm load	8 ohm load
22 AWG	3 feet max	6 feet max	9 feet max	12 feet max
20 AWG	5 feet max	10 feet max	15 feet max	20 feet max
18 AWG	8 feet max	16 feet max	24 feet max	32 feet max
16 AWG	12 feet max	24 feet max	36 feet max	48 feet max
14 AWG	20 feet max	40 feet max	60 feet**	80 feet**
12 AWG	30 feet max	60 feet**	90 feet**	120 feet**
10 AWG	50 feet max	100 feet**	150 feet**	200 feet**

[doctorcilantro]

This is what Duke Spinner echoed I believe:

"Speaker Wire and DF: Amplifiers with a HIGH damping factor have a LOW output impedance. As soon as you start adding speaker wire between the amp and the speakers, the damping factor at the speakers starts to fall. An amplifier with a DF of 400 into a 4 ohm load, has an output impedance of .01 ohms. If you use 5ft of 14g speaker wire, the total resistance of the wire is .016 ohms. If you add this to the output impedance of the amplifier, you have a total output impedance of .026 ohms. This reduces the effective damping factor to 154. Longer runs of speaker wire will reduce the effective damping factor even more"

Mike Sanders at quicksilver got back to me that the Mini-Mites have a damping factor of 5. My tube amps then see very little change in DF when using either

13.5awg or 22awg at 3ft (or 6ft total for one monoblock). The change is in voltage lost: .47 vs. .04

JC

[Duke Spinner]

Exactly ...[]