14 replies to this topic

[mjjensen]

To me, keeping a subwoofer cone in control seems like a good thing - which is related to a high damping factor (correct me if im wrong).

I'd just like to know if there is any audible difference in running a sub at 8 or 16 ohms versus 4 or 2 ohms (in terms of enhanced attack and transient response).

obviously the cost of an amp capable of high power at higher impedances is a limiting factor - but will a sub driven at higher loads benefit from the increased impedance??

also, would there be any way of running my front 4 ohm focal 165kx's at 8 ohms??

.mj

[Mr_Bob]

well, i'd rather run my VRx at 1ohm, than a PHD2 at 4ohm. so i guess it comes down to the sound quality of the amp also.
good quality amps have high enough damping factors to be able to run them at low impedances and still have heaps of control.

there are 3 ways to force your front stage into 8 ohm.

buy 8ohm splits and turf what you have
buy another set of splits and wire them in series, (i wouldn't recommend this)
OR use a jacob's accumatch, i have no idea how the accumatch would affect soudn quality though, i presume it would only make things worse, which defeats the purpose of the exercise.

[Sonic Nirvana]

It's a question of how much damping factor is enough....

My "rule of thumb" is that over 100, you just can't tell, so that if you have that at the load you are driving then no issue.

[mjjensen]

thats what i figured

thanks

[shiny_car]

i agree in that any high quality amp will 'have enough' DF.

certainly there's ample at 4ohm for speakers and subs. most monoblocs are more than fine at 2ohm. 1ohm is pushing things, but not only regarding DF, but everything else. so it depends on the amp and how many subs are used (it makes sense to use as few speakers/sub per channel as possible for the sake of DF).

then again, many people, myself included, put little weight into such specs as DF. it gets back to 'there's enough' if the amps of decent quality.

[ripped]

Quote

Originally posted by Mr_Bob:
well, i'd rather run my VRx at 1ohm, than a PHD2 at 4ohm.

why is there a fetish of you SQ boys paying out the d2? there is nothing wrong with the amp's SQ unless you push it into clipping, then the bad things will happen. don't clip the amp and it'll sound fine!

[shiny_car]

hey, leave me out of this.

[ripped]

images/smiles/icon_mad.gif

[1337shiznit]

Quote

Originally posted by rippedskin:
why is there a fetish of you SQ boys paying out the d2?  there is nothing wrong with the amp's SQ unless you push it into clipping, then the bad things will happen.  don't clip the amp and it'll sound fine!

Agreed!

I bet most of these people haven't used a d2 and the others have no idea what they are talking about.

[1337shiznit]

Back to the original topic, no I personally wouldn't bother with running the subs at 8 ohm, simply because you will get much less power and the difference in damping factor won't be audible anyway.

Here is my question for you guys that think it will make a difference, explain to me what the damping factor is? How it is measured/calculated and how a damping factor that is too low can affect the sound?

There are a lot of people who quote all sorts of specs, but have absolutely no idea about the relevance of them.

[LongGone]

Good point. I was going to write an explanation but realised I really didn't know what I was talking about, so I looked it up,

http://www.eatel.net/~amptech/elecdisc/dampfact.htm

http://www.trueaudio.com/post_013.htm

The bottow line on damping is essentially, once you connect some speaker cable and a speaker to the amplifier the wonderful damping specs become somewhat less wonderful. Most amps still sound quite good regardless of this, so one wonders why we bother talking about dampinf factor at all!

[1337shiznit]

Quote

Originally posted by Hutch:

The bottow line on damping is essentially, once you connect some speaker cable and a speaker to the amplifier the wonderful damping specs become somewhat less wonderful.  Most amps still sound quite good regardless of this, so one wonders why we bother talking about dampinf factor at all!

Exactly!

[fraal_moo]

Apparently passive high pass crossovers get rid of any benifits a high DF would produce as well... I reckon I read that on http://sound.au.com if anyone's interested.

[Dr DJ Choss]

8 ohm in the IASCA format with some big amps maybe, but this day and age amps are better (decent ones that is) so 4 ohms will work well.

air flow and cooling is pretty important too.

I wouldn't worry bout it.

[Dr DJ Choss]

by the way, I use and recommend a full active system design- each amp runs 4 ohms bar the sub amp that's bridged 4 ohm mono. (when it's finished) Each amp only does it's alocated frequency bandwidth for the speaker type it powers and is controlled high and low pass by active crossovers.