Line array power tapering ... plan B?

[Brisso57]

Just a thought experiment for a line array...

Instead of wiring a complex parallel / series arrangement, why not just buy a bunch of cheap Class T boards and wire the speakers 1 per channel (2 per board) & driven from a single, large-enough PS?

Sure the cheap boards don't have much output before distortion becomes a factor, but hey, each board wouldn't be running near max power.

Any "tapering" needed could be done by a pot inserted with each channel.
Another benefit is that drivers with odd impedences (6 ohm, 12 ohm) could be easily accommodated.

Has anyone taken this approach? What result?

Doug

[wilbur-x]

This method of shadowing will work. I like the idea, T-amps are cheap at ebay nowadays. Tapering or shadowing by pot will not solve the issue with regard to delay from the far drivers.
However, many are attracted to the delay effects due to bigger appearance from instruments. So why not give it a try?
A fly would maybe recognize a 18" flute
There are many line array designs out there teasing the DIYer. eg belly formed arrays meant to cover the audience in a big room, is that an ideal approach to live music? In a movie, yes. At home (max 2 rows of chairs) - I think not. The spread of energy represents just the opposite of wave guides and horns. The McIntosh line arrays with horisontal MTM (example:XRT28) have achived a more narrow pattern that reduces the first reflection from side walls. Reviews tells that the XRT's gives enormous feeling of "being there". Why not go this way with your T-amps ? Just a written thought..

[jerryo]

Hi Brisso57,
I have had exactly the same idea; it would be possible to mount each power amp almost directly adjacent to each pair of drive units giving a "very" short speaker cable.
Doing this would also give some interesting possibilities using an active crossover!
Cheers

[Brisso57]

Originally Posted by jerryo

Hi Brisso57,
I have had exactly the same idea; it would be possible to mount each power amp almost directly adjacent to each pair of drive units giving a "very" short speaker cable.
Doing this would also give some interesting possibilities using an active crossover!
Cheers

I agree. I'm further thinking of building a side-firing subwoofer into the base of the LA, and locating the LA boards' PS there also, with a PS "bus-bar" running upwards.

Can anyone suggest a suitable "budget" 2-ch class T amp board?

Doug

[jerryo]

Hi Brisso57,
I don't think the amp has to be stereo. A forum member Digi01 has designed a very compact pcb for the lm3886 chip from National Semi which is mono but two drive units could be attached to it. It is the smallest pcb amp footprint that I know of.
Worth a look.

[Brisso57]

Originally Posted by jerryo

Hi Brisso57,
I don't think the amp has to be stereo. A forum member Digi01 has designed a very compact pcb for the lm3886 chip from National Semi which is mono but two drive units could be attached to it. It is the smallest pcb amp footprint that I know of.
Worth a look.

OK. Where do I look?

Doug

[jerryo]

Hi Brisso57,
if you search for his forum name (DIGI01) with the search facility all his Threads will come up and there you will find it.
Actually I think the Threads title is; "my 3886IGC pcb" so you could search for that. (IGC=inverted gainclone)
The pcb for the amp is 44mm square and he has a matching power supply board for it of the same dimensions so 88 x 44mm for the whole amp!
There are comprehensive details about the amp so should be a trouble free build.

Cheers.

[Brisso57]

Thanks Jerryo.

I'll check it out.

Doug

[Brisso57]

I'm interested in looking at Arjen Helder's Tripath boards. They seem to have a good reputation and the price is reasonable, fully assembled.

Doug

[jerryo]

Yes, they seem to be an increasingly popular choice and as you say they are ready assembled and tested. They are alot bigger than the DIGI01 boards however.