Amplifier kit several hundred watts

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G'day all, looking for a nice amplifier kit to make for a sweet little
girl.....

She has 8 ohm 800 Watt stage speaker bins with 18 inch woofers, and a Yamaha
Stagepas 300 PA system to go with it and I'm looking to make a 400 odd Watt
amplifier for her for Xmas......

I have a good electronic tech background, and would probably prefer to go
for something readily available in Australia, or a good design from the net.
This may happily entail PC board making at home, etc.

I have a similar set of 18 inch bins at home and run them happily from a 300
Watt per channel powered mixer. This also means the bins are never
overdriven.....

Thanks,
Peter



Re: Amplifier kit several hundred watts



"Bushy Pete"

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** There have not been any such kits for a very long time.

( Since the Dynaco ST400 kit from the late 1970's ..... )

It is FAR more sensible and economic to buy one.

Shame if it is not your fantasy Xmas gift for that cute gal  !!

IMCE:

The biggest bargain in new power amps at the moment in Australia is this one
by Behringer.

http://www.storedj.com.au/products/product.php?id73%7

Gives 400 watts per channel, at 4 ohms.

For under $500.

Made in China,  OK   -  but a shameless clone of the justly famous QSC
RMX1450  model.





......  Phil




Re: Amplifier kit several hundred watts



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**Not even then. The ST400 was rated at 200 Watts @ 8 Ohms.

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**Agreed.

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**If it's anything like the Behringer crossovers I've used, it should be
just fine.

Here's one I worked on recently:

http://www.altronics.com.au/index.asp?area=item&idA4%170

 Passable construction quality.


Trevor Wilson



Re: Amplifier kit several hundred watts



"Trevor Wilson"
 "Phil Allison"
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 ** So what?

The OP did not specify 8 ohms.

Power output into 4 ohms is the commonly quoted figure in the world of PA a
stage sound -  as it represents the practical maximum clean power ability of
such amps in normal use.

Then folk like to divide the total 4 ohm watt figure into the dollar price
to get  "dollars per watt".

A result less than 1  =  good buy.

For the Behringer EP1500,  that figure  = 0.625.

http://www.storedj.com.au/products/product.php?id73%7



.......  Phil



Re: Amplifier kit several hundred watts



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**Perhaps I misunderstood these words:

"She has 8 ohm 800 Watt stage speaker bins with 18 inch woofers, and a
Yamaha
Stagepas 300 PA system to go with it and I'm looking to make a 400 odd Watt
amplifier for her for Xmas......"


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**Indeed.

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**OK. I guess that makes the Altronics offering almost as good. (0.67)

Trevor Wilson



Re: Amplifier kit several hundred watts



 "Trevor Wilson"
 "Phil Allison"
 "Bushy Pete"
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** Yep  -  two of them.  What load does that make ?

Dunno a thing about the world of stage PA systems  -  do you Trev?

( Hint  -  they do not need to and only rarely operate in stereo )


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** Not at all, the "dollar per watt " figure improves as you go up the power
output scale in a given design range.

Obvious why -  if you understand the economics of power amp manufacture.

The larger Behringer model is the EP2500 ( 2 x 750 watts @ 4 ohms).

http://www.storedj.com.au/products/product.php?id73%8

This one is also a shameless clone of a QSC model.

The magic figure now is a mere  ** $ 0.43  per watt **.

I'd give the Altronics "no name"  (???) offering a big miss.



.......  Phil






Re: Amplifier kit several hundred watts



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**I never claimed to.

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**Better to examine them first. IMO, their construction is barely average.
It is certainly a long way from what I would call good. I don't know about
the Behringer, though their crossovers are excellent.

Trevor Wilson



Re: Amplifier kit several hundred watts



 "Trevor Wilson"
 "Phil Allison"
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 ** By implication  -  you did.



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**  Read what I just wrote  -   for Christ's sake.


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** Then shut up  -   cos others do.

 All  YOU  have done is to confuse the matter with pedantic crap.

 As bloody usual.




......   Phil




Re: Amplifier kit several hundred watts


On Fri, 16 Nov 2007 21:18:44 +1000, "Bushy Pete"

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Let's hope that you really are "Bushy" and that your nearest neighbour
is at least a kilometre away.

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.

Re: Amplifier kit several hundred watts


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Wot Phil ses. I've been down this path already as an edumacational exercise
for my son, a bass player. Bought a pair of amp kits which he built up with
the intention of bridging them, then we started looking for ways to adapt
the vast variety of nice components I've scavenged over the years, like a
transformer the size of your head, and caps the size of an upper arm. Then
a case strong enough not to bend when you mount this heavy hardware, and...
when I a plan we started thinking about pre-amps, speaker protection circuits,
overload protection for the amp, proper sockets to take professional PA
speaker cables (connectors are $30 and you need 8 for stereo), etc...

It's simply not worth it. You'll spend twice as much to get a result that's
half as good. We quit after building the amp circuit boards and decided to
buy an amp. Spent a couple of nice weekends teaching him how to do solid
speaker cabinet work (a pair of 80 litre bins) and that was much more
productive. The 350+350 watt amp we bought for under $200 never gets cranked
anyhow, but the stereo bins do give his band a small PA or a good bass set
when needed.

Clifford Heath.

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