Amplifiers and Dampening factor.

[malsackj]

I remember a discussion on the effects of dampening factor on speakers and amps.

today I found an article to help us better understand why we need to keep the speaker leads very short.

http://www.prosoundweb.com/article/prin ... er_damping

I feel this would apply equally well in both home and field.

Now this explains why powered subs with powered near field monitors can sound very clean and reduce the mud. Add in a good room and you have the makings for a very enjoyable time.

 

[DIYer]

I remember a discussion on the effects of dampening factor on speakers and amps.

today I found an article to help us better understand why we need to keep the speaker leads very short.

http://www.prosoundweb.com/article/prin ... er_damping

I feel this would apply equally well in both home and field.

It says, "In live sound reinforcement systems..".
Most if not all, home setups don't have +- 100' runs of speaker cables for mains.

Now this explains why powered subs with powered near field monitors can sound very clean and reduce the mud. Add in a good room and you have the makings for a very enjoyable time.

I'll bet that has more to do with active crossover than short run of speaker level cables.

 

[malsackj]

Ok Lets look at the math, if 3 ft at 6 ohm and 12 gauge 0.00159.

3 ft 6 ohm
.005+(.004*2) .01
600

8 ft 6 ohm
.005+(.012*2) .03
200

20 ft 6 ohm
.005+(.031*2) .06
100

40 ft 6 ohm
.005+(.063*2) .13
46

So the dampening went from 600 to 46 in 3 ft to 40 ft if my math was correct?

So would having the speaker cables equal in length for the surrounds and mains add to the benefit of a better room sound? Granted it might be a minor improvement and clean up some of the mud in the 100 to 500 hz range.

 

[Flint]

Something doesn't add up there. I need to look into this more.


As for the equal length question, considering that a passive crossover has several components with high resistance or impedance, I don't think it matters all that much. A single L-Pad, Zobel network, or notch filter will have 1,000x the impact than a milliohm of wire resistance. Also, remember that most passive crossovers are built from components with tolerances of +/-5%, which means much more to the difference in sound than such a low resistance in a wire.

 

[malsackj]

In the article it is stating that it can help with controlling the speakers excursion based on the mass and the power. If all the speakers in the surround system are equal, and if a higher dampening factor helps to prevent a cone from adding to the sound by continueing to move after the signal is not present than I would think that the only factor that changed these numbers is the length of the wire. The fact that such a large difference in value from 3 to 40 feet for the back of the room would be a good demonstation that the rear speakers will have some added mud in the rear.

Seeing as you have pointed out also in the past that when sound comes from the rear we are not able to find direction very easily. Adding some of the mud and lack of clarity from the lower amount of control on equal speakers, was just to add a last detail as to why seperates and short cables can help. Does the rear speakers reproduce as accurately as the fronts with different cable lengths? Possibly yes.

 

[DIYer]

Unless I missed it, that article doesn't say what volume level this condition applies. Is this regarding full scale? Also, what sound source was it subjected to? I would say there is a difference between listening to pure tone vs music when testing.
Anyways, this is good read on speaker cable (covers damping factor). http://www.roger-russell.com/wire/wire.htm

 

[malsackj]

Ok if there information is accurate and a speakers sympathetic vibrations after a peak can only be controlled by and dampening factor from 2 to 20. Than this point will not matter. The article is pointing out that the dampening factor that an amp can present to a speaker to help stop the ringing after a peak is not something to be compared on music or test tones. A good sample to test and work from I would say is a kick drum strike. I had a comparison between a yamaha sub kick and a microphone recorded from a single source. When we compared the wave form on the screen the microphone recorded just one cycle of positive and negative, however the yamaha sub kick recorded two cycles. For those not familiar with the yamaha sub kick it is a speaker in a drum shell and placed in front of the kick drum. If we want an accurate recording and play back than should we be asking for the microphone recording or the sub kick. The sub kick is used to get a fuller and deeper base. The reason I am pointing this out is because the microphone records one signal and the sub kick has two cycles, is the second cycle an undampened mass in motion and would dampening factor help to control? If our speakers and cables are not presented with equal dampening factor than can it possibly be coloring the sound we hear?

 

[Flint]

Okay... I've done more reading and compared it to what I know and have a clearer understanding.

The facts are correct, but the conclusions are flawed. The difference between 10 feet of heavy wire and 30 feet of heavy wire are not going to make an appreciable difference. Like I mentioned above, the crossovers alone will provide significantly more variation that the wire. Heck, variation in the speakers will likely be more impactful (unless they are matched pair - most consumer class manufactured speakers are not matched).

That said, I have ranted on and on about putting the amp close to the speakers and using the shortest wire possible. In my stereo rig the longest wire is a 5 foot run of 10AWG wire. For my surround speakers the longest is a 12 foot run of 14AWG wire. I also don't use passive crossovers which have an extreme impact on damping at the cone.

That is an important point - pass crossovers almost negate all this damping talk.

 

[malsackj]

Thank you Flint for the review and insight.