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[Marc Platt]

   I have dual 18 subs which came with 2x 8 ohm drivers wired parallel inside the box to a 4 ohm nominal load. I re fitted the boxes with NL8 in and NL4 out to the M/H cabs and I used 8 conductor spkr cables. I wired p1-p2 Mf &Hf which goes out to the tops via NL4 and I used the other 4 wires so each 18in driver gets it's own pair.
  On the amp rack patch panel I have the pairs of p3 and p4 jumped to parallel the 2x 18s in ea box to an amp channel but I used a single pair of 12ga for the 2.5 foot run from the NL8 jack in the pannel to the back of the amps, with small jumper wires connecting the p3+ to p4+ and p3- to p4-.


  Will the use of a single pair of 12 ga for 2.5ft run from the pannel to the amp defeat the damping  benifits of running the drivers seperate in the first place, or is the short run not going to make any diference?

[Bob Leonard]

Marc,
There have been many, many discussions concerning damping on this forum in the past. You could do a search, or you could drop damping from your modern vocabulary. Either way you'll find the results to be the same.

[Tim McCulloch]

   I have dual 18 subs which came with 2x 8 ohm drivers wired parallel inside the box to a 4 ohm nominal load. I re fitted the boxes with NL8 in and NL4 out to the M/H cabs and I used 8 conductor spkr cables. I wired p1-p2 Mf &Hf which goes out to the tops via NL4 and I used the other 4 wires so each 18in driver gets it's own pair.
  On the amp rack patch panel I have the pairs of p3 and p4 jumped to parallel the 2x 18s in ea box to an amp channel but I used a single pair of 12ga for the 2.5 foot run from the NL8 jack in the pannel to the back of the amps, with small jumper wires connecting the p3+ to p4+ and p3- to p4-.


  Will the use of a single pair of 12 ga for 2.5ft run from the pannel to the amp defeat the damping  benifits of running the drivers seperate in the first place, or is the short run not going to make any diference?

Typically the "higher" the pinset number, the higher the pass band frequencies... your HF would be on pinset 4, mid (or LF in a 2 way box) on pinset 3, and subs on pinsets 1 & 2.

For example, in JBL's VerTec 4889 the 2-15" speakers are powered on separate pinsets, so LF is on 1 & 2, mids on 3, HF on 4.  There is no pass-through for subs.

Short runs of small gauge wire will not present an issue as its resistance makes up a very small part of the over all cable resistance.  As for damping factor in general, if it's over 20 you're fine.  Don't obsess over 30 year old marketing hype from Crown.

[Marc Platt]

Marc,
There have been many, many discussions concerning damping on this forum in the past. You could do a search, or you could drop damping from your modern vocabulary. Either way you'll find the results to be the same.

So you don't think I should bother with concern over damping?

[Nicolas Poisson]

So you don't think I should bother with concern over damping?

No, because there is no relationship between the claimed damping factor and the perceived audio quality. Some amplifiers show extraordinary DF and poor audio quality, other amplifiers with "low" (or maybe just "honnest") figures revealed to be quite good.

This does not meen the damping factor is complete bullsh*t, this means the way it is measured by manufacturers makes it useless, as most figures in a spec sheet anyway. Well... usually dimensions and weight are reliable.

[Marc Platt]

No, because there is no relationship between the claimed damping factor and the perceived audio quality. Some amplifiers show extraordinary DF and poor audio quality, other amplifiers with "low" (or maybe just "honnest") figures revealed to be quite good.

This does not meen the damping factor is complete bullsh*t, this means the way it is measured by manufacturers makes it useless, as most figures in a spec sheet anyway. Well... usually dimensions and weight are reliable.

I don't mean the amplifier spec "damping factor", but the actual driver's damping which is from my understanding a value that is only relevant to the drivers anyway isn't it? I know the big hype over amp's with higher values on the spec sheet is said to be a bit of a buzz word since that figure (from the amps perspective) plays such an insignificant role when the actual damping at the driver is calculated.
 I was however under the impression that such factors as wire ga and cable length played a major role in the actual damping, am I incorrect?
 

[Jeff Bankston]

a while back i decided to see what the difference between an 8ohm and 4ohm load sounds like. amp used was a qsc 3500. speakers used were two Ciare ndh12-4 8ohm 12" woofers. source used was a nakamichi reciever with preamp outs connected to the qsc 3500. hard rock music with lots of bass was played on the cd player. the loudness and bass tone control were set on max. i ran the amp in stereo with one 8ohm speaker to each channel. then parrelled both 8ohm speakers to one channel(4ohm) load. we couldnt hear any difference in the sound in any way. then i put the amp in bridged mono and connected both speakers in parrallel for a 4ohm load and that meant each amp channel was seeing a 2 ohm load. no difference in the sound and that includes tightness off bass , sound quality and punch. the speaker cables used were 14 gauge and about 20 feet long. i decided to do this test when a guy i know told me i was hurting the sound by connecting 4 ohm speaker loads. he was here during the test and was surprised that there wasnt any difference. i have "heard" that long speaker cables kill the damping but i have always kept my cables at 25 feet max and use 10 gauge wire for the woofers in the pa system.

p.s. i'm trying to improve the way i explain things. i hope this post is easy to understand.

[Marc Platt]

a while back i decided to see what the difference between an 8ohm and 4ohm load sounds like. amp used was a qsc 3500. speakers used were two Ciare ndh12-4 8ohm 12" woofers. source used was a nakamichi reciever with preamp outs connected to the qsc 3500. hard rock music with lots of bass was played on the cd player. the loudness and bass tone control were set on max. i ran the amp in stereo with one 8ohm speaker to each channel. then parrelled both 8ohm speakers to one channel(4ohm) load. we couldnt hear any difference in the sound in any way. then i put the amp in bridged mono and connected both speakers in parrallel for a 4ohm load and that meant each amp channel was seeing a 2 ohm load. no difference in the sound and that includes tightness off bass , sound quality and punch. the speaker cables used were 14 gauge and about 20 feet long. i decided to do this test when a guy i know told me i was hurting the sound by connecting 4 ohm speaker loads. he was here during the test and was surprised that there wasnt any difference. i have "heard" that long speaker cables kill the damping but i have always kept my cables at 25 feet max and use 10 gauge wire for the woofers in the pa system.

p.s. i'm trying to improve the way i explain things. i hope this post is easy to understand.

I am actually still running at 4ohm loads per amp ch, just instead of the parallel connection of the 2x18's taking place inside the enclosure (as orig) I wired each of the drivers in each box with seperate pair of 12ga and then they are wired to parallel at the amp rack (4ohms nom) Just doubled the effective wire dia.
  When you tested the amp brdg mono with the pair of drivers parallel, you did not hear any difference? Wow that is not what Id expect with double the power.

[Tim McCulloch]

  When you tested the amp brdg mono with the pair of drivers parallel, you did not hear any difference? Wow that is not what Id expect with double the power.

That's because VOLTAGE drives speakers, not "power."  If the voltage at the loudspeaker terminals is the same, the SPL will be the same.

[Marc Platt]

That's because VOLTAGE drives speakers, not "power."  If the voltage at the loudspeaker terminals is the same, the SPL will be the same.

Wouldnt the voltage increase when wired that way?

[ProSoundWeb Community]