Here is my plan...critiques and suggestions encouraged

[Dotay]

OK, I've been doing a lot of reading on this site for around a year now I think and I think I've finally convinced myself to take the plunge and try and build a set of DIY speakers for use in my HT setting. I think for my needs and budget the Natalie P design in a tower formation will work well for me. I think I'll use one of the WMTW designs in dawaro's thread for the center speaker. I'll probably use the Modula MT design for the rear speakers. I'm planning on using the RS28A tweeter for all of these speakers.

Now...from what I understand these speakers probably won't really make my cheapo Denon receiver very happy so I'll probably have to go ahead and upgrade to seperates while I'm at it. I'm pretty sure I've decided that I want to go with one of the GC chipamps due to their relatively low cost and their reportedly good sound. I was think that five LM3886's from chipamp.com in the mono channel configuration might work well for me (this is definitely an area that I will take suggestions from those of you that are in the know as I know very little about amplifier design).

This then leads me to a pre-amp. I could probably use my Denon receiver as a pre-amp for a while if I really need to but from the reading I've been doing I think that an Outlaw 950 will suit my wants quite well. I don't need any fancy video switching or anything like that and I'd like to stay ~$500 if possible and this seems to be the going rate for these amps used.

Well, that's my plan (subject to change at any moment :P ). I'd really like to hear your thoughts and whether or not anyone sees any glaring holes in my proposed plan. Specifically I'd like to hear thoughts on my choices for amplification and whether or not you feel the LM3886's will work well with the speakers I'm planning on building. I believe CJD said somewhere in his amplifier thread that a good quality 5 channel chip amp could be made for ~$400. So my amplification budget is under $1000 if possible. If not I can always buy stuff over time and do it that way.

[GrahamT]

Just curious, why not Modula MTM up front with the Modula Center and Modula MTs for surrounds?

[thylantyr]

So my amplification budget is under $1000

You want 5 amp channels, perhaps chipamps but your
budget for amplifiers is ~$1000 ? So why mess around
with chip amps? :lol:

I'd rather get three Crown XLS402 amplifiers to offer
six channels for $750 and it will offer more clean power
than the chipamp and sound just as good. Headroom would
be superior with the Crown pro amp too.

Or....

five amp channels;
Get two Crown XLS402's - $500
Get one Crown XLS202 [or XLS402] - $200 [$250]

Bridge the XLS202 [or XLS402] for 1 channel operation to drive the
center channel, you will have incredible headroom.

But if it was me, I'd raise my amplifier budget just a tad
and get a more robust QSC RMX series of amplifier,
it has variable speed fans and has a better heatsink design.
You would be closer to the $1000 budget limit by using RMX.

Most people that use XLS in HT will do fan mods, either
replace the fans with 'quiet fans' or insert a resistor to
reduce fan RPM to reduce fan wind noise. Others have
disabled the fan for HT use with no issues as their speakers
didn't present a big load.

[JonMarsh]

Probably because of the difference in crossover cost- not insubstantial.

Some Denon recievers won't have any problem with the Natalie P or similar- but they need to be rated for 4 ohms. Those that suggest 6 ohms or higher probably won't be happy when things get cooking.

I don't really have any experience with that specific chip amp- again, power supply, layout, and cooling are pretty important. If you run chip amps in bridge to get some reasonable voltage swing, then a 4 ohm speaker load looks like a 2 ohm load to each chip amp. Possibly not a good thing. You might be better off with your Denon- at least, try it out.

It might be that Audiogon is your best bet- its often possible to pick up good used separates at a fraction of their original price. I've bought several Aragon amps that way.

~Jon

[Dotay]

Just curious, why not Modula MTM up front with the Modula Center and Modula MTs for surrounds?

Cost mainly. The Natalie P's are cheaper by what I would consider a considerable margin. I haven't heard either design yet but from what I've read the Natalie P's sound great, not that the Modulas wouldn't, just not sure if it's worth the extra ~$250. Now as far as the Modula Center vs. the WMTW center that's still up for debate. I'm leaning more towards the bigger center because the two designs will be pretty close in price (I think) and I like the idea of having the same tweeter all the way around.

[Dotay]

You want 5 amp channels, perhaps chipamps but your
budget for amplifiers is ~$1000 ? So why mess around
with chip amps? :lol:

I guess I should clarify this a bit. I was including the pre-amp in this budget as well. So assuming I could get an Outlaw 950 for ~$500 that would leave ~$500 for amps. That's why I was leaning towards chipamps...plus I think it'd be pretty neat to build my own amps. If however these wouldn't work to drive my proposed speakers I'll adjust my budget accordingly.

[Dotay]

Probably because of the difference in crossover cost- not insubstantial.

Some Denon recievers won't have any problem with the Natalie P or similar- but they need to be rated for 4 ohms. Those that suggest 6 ohms or higher probably won't be happy when things get cooking.

I don't really have any experience with that specific chip amp- again, power supply, layout, and cooling are pretty important. If you run chip amps in bridge to get some reasonable voltage swing, then a 4 ohm speaker load looks like a 2 ohm load to each chip amp. Possibly not a good thing. You might be better off with your Denon- at least, try it out.

It might be that Audiogon is your best bet- its often possible to pick up good used separates at a fraction of their original price. I've bought several Aragon amps that way.

~Jon

Thanks for the reply. My receiver is a Denon AVR-1603 and I'm pretty sure it's only rated at 8 Ohms. It's a pretty basic receiver and it has worked fine with my current speakers (Energy C-7's) but I doubt it would be able to handle these speakers. Like you said however, I could always try it out and see how it did.

I've also been checking audiogon pretty regularly. Any suggestions on amps to keep an eye out for?

[megame]

you could also try http://www.twistedpearaudio.com/ if you want to use a gainclone... the ref_c seem to be all the rage at diyaudio at the moment.

[cjd]

Paralleled LM3886 (or a LM4780 paralleled) would be quite happy with 4ohm speakers on a +/-35V supply (25-0-25 trafo). Should do 120W or so into 4ohm. In fact, a single LM3886 is quite comfortable with a 4ohm load.

The Mauro design is superb and a step away from the basic chip-amp design.

C

[Dotay]

Paralleled LM3886 (or a LM4780 paralleled) would be quite happy with 4ohm speakers on a +/-35V supply (25-0-25 trafo). Should do 120W or so into 4ohm. In fact, a single LM3886 is quite comfortable with a 4ohm load.

The Mauro design is superb and a step away from the basic chip-amp design.

C

I've been doing some reading on this design on the diyaudio website and it definitely looks different than the other chipamps I've looked at. Most chipamps I've seen had the power supply board seperate from the rest of the amp while this design apears to have the transformer connecting directly to the board. Anyone want to comment on the differences between the two approaches?

I really need to do some more reading before jumping into the amp project. I'd feel pretty comfortable with the speakers, but the amps seem to have so many more variables. If I were to run 5 channels would I need a huge transformer or 5 smaller ones? It's questions like this that I need to figure out way before I start ordering parts...ok now I'm just talking out loud so I'll stop now... ops:

[thylantyr]

The Mauro design is superb and a step away from the basic chip-amp design.

I see too much electronic baggage in the design. I'd rather
use a standard design using LM4780.

http://www.diyaudio.com/forums/attachment.php?postid=609507&stamp=1112280850

The power supply design is 'text book', nothing special.

Cost: [single channel]

http://www.twistedpearaudio.com/

RevC PCB Set (stereo pair) $25.00 USD
RevC Kit (PCB set + parts) $95.00 USD

So for a 2 channel amplifier you need 2x ..

$95 x 2 = $190 ... plus

You will need to provide a transformer with two 24V secondaries, power fuse, input (RCA) and speaker output connectors, wire, chassis, etc.

Add another $100 for the rest of the parts?

I can get a brand new pro amp for $200 that would beat this, a better pro amp for $250, and a 2400w one for $400.

[Brian Walter]

Thylantyr, I think you miss-read the pricing for the RevC amplifier kit. The $95 includes a set of PCB's and parts, that is for a stereo pair, you don't need to multiply by 2. As for whether the $200 pro amp would beat this, in power most likely, but sound quality, I don't know, I haven't heard either one. Reviews have been rather favorable for the RevC amp. I guess it all boils down to whether you want to build something yourself or not. Some DIY'ers don't limit themselves to speakers. I have built both speakers and amplifiers, and I enjoy both about the same. For someone living in a cold region, amp building in the winter can beat working in an unheated workshop building cabinets.

[thylantyr]

Thylantyr, I think you miss-read the pricing for the RevC amplifier kit. The $95 includes a set of PCB's and parts, that is for a stereo pair, you don't need to multiply by 2.

The site isn't very clear. But now that you mention it,
the comedy level rises. Four PCB's to make a 2 channel
amp seems 'busy'.

The BrianGT's LM4780 PCB's are better as the 4780 is
dual LM3886 and he wired it up for parallel mode
to drive 4 ohms. 1 PCB, 1 channel.

[Brian Walter]

Thylantyr, when they worked up the PCB design for the RevC board, the designer specifically left the power supply portion off so that he could use them as monoblocks, but the kit contains the separate power supply boards and parts. I personally would prefer to power a multi-channel amp with a single power supply (I know others might prefer otherwise), so getting all those extra PS boards and parts included with the kit would be a waste for me.

For the price, I think BrianGT's LM4780 kit would be a better way to go. It's certainly a more robust amp with the channels paralleled. The sound quality may not be as good as the RevC, but I suspect I wouldn't be able to hear the difference between the two.

Brian Walter

[Brian Bunge]

Brian and I are actually talking about running quad 3886 paralleled per channel for a 2 channel setup to go with my big Dayton 3 way towers. I figure having an amp that can handle a 2 ohm load is a good thing with these monsters. Brian recommended the multiple 3886 chips both for better power handling and better heat dissipation. I'll have to see how much this will cost though as Kevin at DIYCable has 2 channel Hypex amp kits starting at $495 including the case. It'd also run cooler and take up less space so that might be a consideration as well.

[DeanP]

Is there a link to "BrianGT's LM4780 kit "?

[ThomasW]

http://www.chipamp.com/

[pjchooch]

The only thing the RevC has in common with other 3886 GCs is that it has a 3886 in it. It uses it in a completely different way though. It like comparing two amps that use the same output FETs but different topologies.

This is a good read on how it works (by the designer): http://www.twistedpearaudio.com/docs/project_my_ref.pdf

I have built a set of these and they are really amazing. The power supply is integrated into the same board as the amp, but uses the big caps as shielding between the rectifier and the amp section. Zero noise. Worth a serious look. I also have a 4780 amp from chipamp.com. It is very nice, but a very different animal. The RevC is in a differnt league in terms of sound quality though.