Ive heard that having an amp(A) with a high damping factor means it can control the cone better than amp(B) with a lower damping factor even if amp B has moderatley more power (or something like that). Anyway what is a good/high damping factor? Is something like 135 good?

Thanx for any help!

You're right, damping factor describes an amplifiers ability to control a woofer cone. It's the ratio of rated load impedance to the internal impedance of an amplifier. The higher the damping factor the more efficiently an amplifier can control unwanted movement of the speaker coil. High damping factor is crucial for subwoofers and the higher the damping factor the better.

It is debatable if anything over 50 is audible even though the best amps like ARC Audio, Zapco, Tru-Tech, Phass etc have over 1000 many times.

Damping factor is calculated by dividing the speaker impedance by the output impedance of the amplifier. In other words the damping factor will decrease as the speakers impedance decreases. This means an amp optimised at 4 ohms will provide tighter bass than when they're running at 2 ohms. A lower damping factor will leave bass notes sounding soft and undefined, regardless of the amplifiers power output. You can see by this that a smaller 100 watt amplifier with a high damping factor can often sound better than one twice it's size with a low damping factor.

We often just aim for over 50-100 so yes, 135 is quite good. :)

That being the case, I was looking around in Jaycar today and saw this amp http://www1.jaycar.com.au/productView.asp?ID=AA0434&CATID=24&keywords=&SPECIAL=&form=CAT&ProdCodeOnly=&Keyword1=&Keyword2=&pageNumber=&priceMin=&priceMax=&SUBCATID=595
Judging from the specs it looks to be pretty good bang for buck. Would you say this amp could power a Image Dynamics IDQ12 D2 wired to 4ohms acceptably for SQ? I know it wouldnt be as good as a more expensive amp but the more money I can save the better.

It would be okay but of course for a little more you would get much better. For example, lets compare the specs of an ARC Audio amp to the Jaycar:

1. Jaycar AA0434 Specifications
- Power/channel @ 4 ohm: 150 W RMS x 2
- Power/channel @ 2 ohm: 230 W RMS x 2
- Power output (Bridged 4ohm): 450 W RMS x 1
- Frequency Response: 20-30Khz ± 1db
- Total harmonic distortion: Less than 0.08% @ 1kHz
- Input sensitivity: 200mV to 3.5V
- S/N ratio: Better than 80db @ 1kHz
- Quiescent current: 0.86A
- Maximum current: 56A. - Damping factor: 136


1. ARC Audio 2100XXK Specifications
- Power/channel @ 4 ohm: 100 W RMS x 2
- Power/channel @ 2 ohm: 180 W RMS x 2
- Power output (Bridged 4ohm): 380 W RMS x 1
- Frequency Response: 20-20Khz ± 1db
- Total harmonic distortion: Less than < 0.01% @ 1kHz
- Input sensitivity: 200mV to 2.5V
- S/N ratio: Better than 80db @ 1kHz
- Quiescent current: 0.93A
- Maximum current: 43A. - Damping factor: 1000

See the power specs of the ARC are actually less than the Jaycar but have a peek at the damping factor of the two.... enough said.

ok good, just checked and my Eclipse amp has a damping factor of better than 200 :)

whats slew rate refer to?

The ARC Audio 2100XXK amp retails for $799. I could buy three of the jaycar amps and have change, is the extra $510 worth it?

Im thinking of buying 2 of the Jaycar amps and 2 of the Image dynamics 12" subs because its only a couple of hundred than what I would have spent with one ID sub and ARC amp and Id have twice the cone.

Jaycar amp : x1=$289 x2=$265 x4=$235

Arc Amp : x1=$799 (retail) (multiple buy discounts ???)

ID subs : x1=$449 (retail) (multiple buy discounts ???)

Idea 1) $738 for a single jaycar amp and single Image dynamics 12" sub

Idea 2) $1428 for the dual jaycar amps and dual image dynamics 12" subs

Idea 3) $1248 for the single ARC amp and single Image dynamics 12" sub

What would you reccomend bang for buck?
Should the dual setup be better (SQ) than the single with the ARC amp?

Are there cheaper prices for buying multiple ARC amps or ID subs? If so what are the prices/conditions?

Thanx!

whats slew rate refer to?

Sometimes referred to as damping factor for tweeters, the slew rate describes the amplifiers ability to accurately control fast direction changes of a speaker cone or dome. Have you even turned your stereo up to discover that your cymbals sound like someone throwing a brick through a glass window? That's because the amplifier simply wasn't fast enough to accurately reproduce the high frequency ring of the symbols. Measured in volts per microsecond, a low slew rate softens the definition of a sound signal which blurs transients and causes the sound to appear muddy. A high slew rate means the amp responses faster which ultimately results in crystal clear highs. :D

The ARC Audio 2100XXK amp retails for $799. I could buy three of the jaycar amps and have change, is the extra $510 worth it?

Did you read what I wrote about the amplifier specs. You might find the sound coming from the single ARC is much better than the three Jaycars you're planning on buying.

Now don't get me wrong, you're perfectly entitled to ignore what I say dude. All I ask is that you research it before you go ahead and buy. Many people have wasted a lot of money buy going for the cheap amplifiers. Only to be shown later when I let them borrow a better amp on trial which is half the size.

As for buying ARC and ID in bulk, of course you'll get cheaper prices. You might also wish to have a look at our specials page (http://www.fastfoursforumscarclub.com/temp/fhrxstudios/specials.asp). :D

Look into other brands as well, if you dont want to spend $799 on the ARC then at least get something that is close like an Audison SRx2s RRP$599. Their are plenty of amps out there and i think FHRX knows just about all of them. Look to spend at least $450 on an amp.

I only put forward those plans as alternatives as there'd want to be a lot more performance for $510 extra. BTW I didnt say I was going to get 3 Jaycar amps, just saying I couldlol .

I tend to consider what you say about audio gospel, so in light of your reccomendations (which are very much appreciated!) Im going to try and get some down to audition. Wish me luck! This might not actually happen as there is no-one I can find down in Tas that sells these brands as normal stock. If all else fails I'll see if I can get a few (about 3) different people to audition them and get back to me. This is probably what will have to happen...better than nothing.

At about $1165 at my last check (still trying to get final prices) this seems to be a good package. Theres a few people at work that are interested too, maybe a bulk order?

Still one question. What would be better for SQ?
1) Bridging to one channel and running at 4ohms.
2) Running in 4Ohm 2 channel mode, one 4ohm channel to each VC.

Thanx heaps for your help...again!

Number one out of those two choices. I don't recommend you run indiviual voice coils with individual channels.

I've seen too many people blow too many things up using this method in the past. :(

Cool, I was thinking that if one coil had a slightly diff signal to the other things would go wrong, but I've also heard of people doing it.

I went into a Car Audio store today and talked to them about the damping factors of different amps. They said that an amp with a damping factor of 50 was much better than one with a damping factor of 1000. Isnt that the reverse of what has been said in this thread? Should I go in there and tell them that 1000 is better than 50 and set things right...I found this page which goes into detail about what the damping factor is http://www.classic-audio.com/marantz/mdampingfactor.html. Basically Ive come to the conclusion that you need to look at the frequency response, damping factor, slew, phase shift, distortion, RMS @ x.xxVolts, etc as a whole rather than going, this 400WRMS amp is better than that 400WRMS amp soley because its damping factor is better. (It probably will be but it might not)

Would it be possible for someone to write up a list of good and bad figures of amp specifications just so people have an idea of what seperates a good amp from a poor amp.
eg:
Damping factor of 10= bad 100+ =good 1000+ =excellent