A9-B power requirements

[revans]

Hi there,

Just wondering how much power (in watts) would be necessary for a supply to run the Amp9-Basic? Considering a new project with the Amp9 and was thinking about running it with one of these: http://www.wellforces.co.nz/index.ph...emart&Itemid=2

Also, I see you can run it from 12-24V... what's the difference between running it at 12V or at 24V? Higher power output or something like that?

Thanks.

[krilli]

It depends a lot on what you're using with the thing. You CAN squeeze 400 Watts out of the thing if you really lay on it.

You can get away with 30W per channel, 50W per channel is nice, and 100W per channel is the max. you can squeeze out of the amp with the right kind of load. Then add a "fudge factor" of say 10%.

So at 30W/channel you'd want a ~130W supply, at 50W/channel, around 220W is good, and ~440 for max blast power party.

edit - and yes, by doubling the voltage, you get quadruple the output wattage.

edit 2 - This post is the bomb: http://www.41hz.com/forums/showthrea...can-I-get-from ... shows you how to calculate the power you get into the speakers you have at the voltage you're running

[V-bro]

To get a more lively 'feel' of what this means (as it is by no means linear) I always like to refer to the THD+N versus output power graphs in the Tripath datasheets. They have two graphs to show what happens at two different supply voltages and load:

[revans]

Ok, thanks guys. Btw, this is in relation to these kits: http://www.theloudspeakerkit.com/pro...t-Speaker.html
I'm mulling knocking a few up and am considering the A9-B as an amp for them.

Krilli, I used the formula on the thread you linked to, and with 24V got max power per channel of 32.4W... does this mean I'd really only need a 140W supply?

Just thinking though, how well would they go together? The M4s are 8 ohm and relatively low efficiency... (85dB 1W@1M)... might not be as loud as they could... then again that's not really what I'm after.

[V-bro]

In the past I have used down to 4A supply, BUT at 15V with good results. BUT that was in a very small room and I never pushed it out that loud...

I don't think I would be really pleased with these M4's, but that's me and I don't know them... so my comment is pretty much useless for you...

They use a type of tweeter I never really liked and the efficiency at 8 ohms is pretty low.

[revans]

They use a type of tweeter I never really liked

Haha, I'm definitely not enough of an audiophile to tell the difference between tweeters

Having finished the boombox, I now want to make an actual set of speakers, however shipping costs are once again killing me (Tang Bands in the boombox had free shipping off eBay ). The LSK M4's are far cheaper (and simpler, with the slot-together box) than any of the kits from Madisound (NZ$150 shipping ). Surprisingly, there's actually now a retailer of DIY audio stuff in NZ (www.hasaudio.co.nz), but their prices are still > M4s

I reckon they'll probably sound better than my boombox, which to my untrained ears sounds fine (except for a lack of bass).

EDIT: Another thing, I actually found an Impulse H6 kit from the HAS store mentioned above on Trade Me (NZ eBay): http://www.trademe.co.nz/Browse/List...x?id=269658551
It's going for NZ$200, while it retails in their store for NZ$490, and I found it on eBay for NZ$560. It's not what I'm after at the moment but it seems like a good deal... Is the H6 as famous as they make out? Any comments?

[V-bro]

That H6 looks a million times better than the M4 kit! I'm quite sure it sound better too!

[revans]

Only thing is, they're just a bit on the huge side (for me anyway)... though it is a good deal. The M4s would be NZ$400 as a comparison... Hmm, this is sounding convincing. I guess I could buy them as a future investment

[krilli]

OK, skimming this, quick answers
1) The max power calc depends on impedance
2) 8 Ohm / 85dB is quite low, I'd skip those particular speakers (I'd say they call for a 100W plus amp, running at 50V)

[Scratchy]

Have a look at these DIY designs:
http://sites.google.com/site/undefinition/diy

The Overnight Sensations are small and rated quite highly.
One of our members here WWWJD has built a pair of these with an AMP6:
http://techtalk.parts-express.com/sh...d.php?t=212169

His post is here:
http://www.41hz.com/forums/showthrea...ed-and-awesome!