[Kevin P]

We have finished development on our LM4780 based amplifier kits and we are moving forward to sourcing parts for two channel versions with both 50W/Ch & 100W/ch options.   We could offer a multi-channel version but it would require ordering parts in quantity and I'm not sure how they would sell.   Most of my customers are two-channel people and the multi-channel crowd doesn't seem to be interested in kits.  

These are really simple to assemble.   Some of my kid’s toys are more difficult to assemble so the learning curve is not steep.    The chassis is the same we used for the Exodus digital amp and we are using Cardas parts on input & outputs.  

Sound quality should equal any of the audiophile based amplifiers using the National chips.  

Total cost for complete kits would fall in this range:
$300          2-Channel 50W/ch
$400          2-Channel 100W/Ch

$650-$700   5-Channel 100W/Ch


How many people would show an interest in a multichannel kit in that price range?

[MaxCast]

I may be interested...depends where my system is at the time of the offering

Could you make it modular?  Meaning you could build a 2, 3, 4 or 5 channel amp.  Like you said, many of us have a 2 channel amp but may need to add 3 for 5.1.

[Kevin P]

It is tough to make a "one size fits all" type of product.   For more channels of amplification you have to increase the size and/or number of power transformers.  You would also need to add input & outputs on the rear panel.   The only way to do that is to either add a new rear panel or have one panel with holes cut for the highest number configuration (lets say 8-channels) and provide plastic caps to cover unused holes.

The transformer issue is a little more problematic.   The smallest two-channel amp only needs a 250VA transformer.   A 6-channel 100W/ch version would require at least a 1000VA transformer so upgrading would mean throwing out your transformer and adding a larger one.   Multiple smaller transformers can get very expensive and there are some layout problems with trying to put a transformer on every module.   Ideally we want to keep the AC portion of the amp separated by a good distance to prevent noise pick-up.   The transformers also cast an EMI field that is best to keep some distance from the amplification.   We have shielding designed between the AC side & the amplification side of the chassis and if you used multiple small transformers on each module you wouldn't be able to keep this separation.

Overall you will be able to upgrade to more modules but it will likely require a rear panel change and transformer swap.

[bubba966]

Well, I've already talked to you before about a 7 channel amp.

Buuut, that wasn't for this product.

Is something like a 5x100w & 2x50w combo possible in the case? That way the 2 50w channels could be used for the rear center channels, and the other 5 100w channels can be used for the L/C/R/LR/RR speaks.

Something like that would work great for a DD EX/DTS ES 7 channel setup as there's really not much going on in the rear center channels.

At some point I would like to upgrade my amplification. But that's not really a priority right now (finding a job is as a lack of income sucks... ). And I honestly couldn't guess when I'd be in the market for a 5 or 7 channel amp. But I do really like the $700 or so for a 5x100w amp.

[Kevin P]

There is room in the current chassis for 16 amplifier channels at 60W/Ch or 8-channels at 120W/ch.    The problem is there is no way that you can fit 16 standard speaker post on the rear of the chassis and a power transformer of appropriate size might not fit.   After playing with the rear panel I think our limit in the current chassis is probably about 8 speaker binding post on the rear panel (and that is pretty tight), so you could have a 8 x 120W version if the power transformer will fit.

The National LM4780 is basically two LM3886's in one package.   The LM3886 has been used in several high-end amplifier designs.  It has overheating, over & under voltage protection, speaker short-circuit protection and a slow-start mute function.   The amplifier is simple.... the design work has been very easy as National Semiconductor makes the use of these very straightforward for the designer.   There are a number of ways to use the LM4780 and most of the configurations can be achieved with this board.   If you follow the chip amp forum over at DIYAudio you are aware of all the variations, inverting, non-inverting, buffers etc....    We have most of the basic configurations covered and the amplifier board uses a special layout to keep multiple low impedance capacitors VERY close to the chip.  

These will also make their way into some active speaker designs we have cooking.   The cost of quality amplification is one of the biggest reasons active designs have never flown.   We plan on mating these with several of the new Adire Audio XBL^2 drivers (design work already done) which should provide new levels of performance in their price catagory.

[dayneger]

Sounds like you might have an amp alternative for people who make their own Linkwitz Orions.

Some active systems based on those new drivers could be pretty interesting!

Dayne

[mac]

The problem is there is no way that you can fit 16 standard speaker post on the rear of the chassis...

Neutrik Speakon® - 4 or 8 conductor jacks would fit nicely.

Sounds like you might have an amp alternative for people who make their own Linkwitz Orions.

That's exactly what I was thinking.  

[Kevin P]

Yes.... I've looked at other solutions but you really cut the potential market when you go with a proprietary non-standard interface.  

The people who have $500 speaker cables wouldn't be able to use them and the system could never sound right with cheaper cables.  

Funny you mention the Orion.   I have a couple of the Linkwitz crossover boards here and we can just squeeze them in the chassis along with the required 6-channels of amplification.   I'd have to build one up but I'm fairly confident we could have a one box solution for his amp & crossover.  He was the inspiration for this project and I'd like to offer some active projects in the future.   These amplifier modules are perfect for the application.