Matching sub plate amp with driver

Assuming you can't test before you buy (choices in New Zealand are limited you know!) - is it possible to determine a good subwoofer plate amplifier by simply looking at the specs?

I'm hoping to use the following sub plate amp:
http://www.acousticconcepts.com.au/sub_specs.htm

with an adire audio Shiva 12" driver:
http://www.acousticconcepts.com.au/shiva_mark_ii_sub.htm

I'm concerned at the apparent low damping factor of the amplifier (200) compared to Adire audio's own plate amplifier (350+ depending on model).

Does the damping factor matter? (I've read about the theory - but being able to calculate the damping factor doesn't really help me - what I want to know is - how does a "low" damping factor affect the sound?)

Does a low damping factor mean I'll need to put the driver in a smaller sealed enclosure to assist the amplifier achieve a good transient response?

I'd like to use the sub mainly for rock / pop music - so (I'm guessing) speed and accuracy are more important than SPL or low frequency. Will plan to use the driver in a dual vented / sealed enclosure.

Any thoughts / comments appreciated,

Thanks,
Dave.
 

kelticwizard

diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
Dave:

Several days and still no answer.

I have always gone on the assumption that any commercially produced product would have a satisfactory damping factor. However, I am not really up on amp design-I have built a few small ones, know the principle, but that is about it.

With no answers, you might be on the wrong forum. I would ask the mod or webmaster to move this question to the solid state amp forum. The builders over there would likely be able to give you some good advice.
 
Thanks kelticwizard,

Yup - I should have posted in solid state.

I've done some more digging - and the more I read - the more it seems damping factor is a marketing term. Probably not as bad as PMPO and the like - but meaningless by itself.

Instead of worrying about metrics and measures - I've asked a few people who have built / used the plate amp in question (www.redgumaudio.com) - and they all have given it the thumbs up.

I'd "trust" the Adire AVA range - problem is the shipping to NZ is soooo expensive - Australasia is the only way to go - which means local product. The only one I've found is redgum.

BTW - We do make some excellent full range pre, integrated and power amplifiers (Plinius and Perreaux) - but those brands don't maek plate amps for us sub maniacs.... I mean fanatics... I mean ... :)

Thanks,
Dave.
 

kelticwizard

diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
Dave:

Most of the plate amps seem to come from one or two companies in Taiwan. I suspect they are made in China. Keiga is one, I forget the name of the other.

Parts Express and others over here simply add their name to them.

How's the shipping from Taiwan over there? I can find you Keiga's homepage-I saw it before.

Still, there is much to be said for supporting your local company. As long as the money is anywhere comparable, that is the way I would go.
 

kelticwizard

diyAudio Moderator Emeritus
2001-09-18 2:33 am
Connecticut, The Nutmeg State
I checked Redgum plate amps. When you do the currency conversion, the prices seem comparable to what is available at most places in the US.

By the way, just to increase your list of options I include the home page of BK Electronics, an English company that cyber friends over there highly recommend. I haven't the slightest idea of shipping, taxes, import charges or whatever, but I figured New Zealand and England might have some sort of deal.

Anyway, click on "Modules and Hybrids" at www.bkelec.com
 
Dave,

From the blurb, the Redgum sounds like it has a good chance of outperforming Adire's far east manufactured plate-amp. The only thing special about Adire's is that they have the factory remove a lot of the bass-boost junk commonly found in these amps. There is a good chance that a very similar plate amp is available in NZ and armed with a schema you could rip out what you'd need to approach equivalency.

As far a damping factor goes it is the inverse of the output impedance. So the Redgum has an Ro of 0.005 and the Adire of 0.003. Now in use you add the impedance of the speaker, say 8 ohms, and of the speaker wire, say another 0.005 (wild guess there) and you have a total impedance of 8.010 for the redgum and 8.008 for the Adire.

As long as the damping factor is >10 you can consider them to be all the same.

dave
 
kelticwizard and Dave

Thanks for your replies. It's not suprising I suppose that most things these days come from Taiwan - not that that is a bad thing - but means at least the stuff you guys get in the USA (or Canada :) - unless home grown, is the same quality as is available here.

Thanks for the Keiga and BK electronics references.... unfortunately - shipping from the UK will be worse than from the USA.

I always end up going back to e-bay and fantisizing over buying an old 70's Marantz integrated or receiver (but again - the shipping $ that turns the dream into a nightmare)

Ah well - there must be something good about being upside down on the world's bottom :)

Thanks,
Dave.
 
Dave Bullet said:
Ah well - there must be something good about being upside down on the world's bottom :)

The world's best rugby players (but not the best rugby machines*). Lots of cool members. The dude who started this forum. The AKSA. Water Rats. (i know those last 3 are in Oz but i'm including the entire hemisphere)

* reserved for some guys i've been helping out for the last 15 years -- ScrumMaster (the web site is way out of date -- but the premier model, the International, is basically unchanged. It has a built-in pnuematic computer of ingenious design.

dave