sconeman wrote:
I'm almost certain the speakers are 8 ohms. It doesn't say on the units themselves, but on the amp outputs the label says (speakers 8 ohms) I assumet the sub is as well. If I just take my multimeter and test the resistance across the speaker will it give me the right info?
Yes, you can just stick the DMM on the input/output of the speaker to get Ohms. This matters, but not a lot. What matters is the efficiency. For "efficient" speakers, and lets define that at >90db at 1meter with 1Watt, you can get away with...... drum roll... one watt. Seriously. So 560W is silliness and unnecessary. Plus it gets expensive. Lets be fair and say that the speakers they sold you are about 84db per watt at a meter away. For each increase of 3db we need to double the last wattage. So, 87db is 2watts and 90db is 4watts and 93db is 8watts and 97db is 16watts and 100db is 32watts. I think once you hit 32watts requirement you really probably have more power than you need to get some incredibly loud sound out of almost any speakers. Imagine 32watts into a 100db per watt and one meter speaker. The speakers would walk across the floor.
I know one watt sounds crazy, but many many tube amps use less than one watt and you can get very respectable volume into efficient speakers. But, we are not talking about tube amps and we are probably not talking about efficient speakers. We are probably talking about something from Peter Daniels at audiosector.com or chipamp.com or 41hz. There are a few others. Using the LM3886 chip (you can get it for 3.50 each channel at apexjr.com) is a great great choice. The sound quality is spectacular for the price. You can buy boards for, I think, $6 each at chipamp.com. The power supply will be a bit expensive cuz of the transformer. Try to find a cheap 18V toroidal transformer with, for 6 channels, probably a minimum of 600VA. You could give or take a few hundred VA on that but overkill is a positive thing with the transformer and if you can find one that gives closer to 800-1000VA its going to make a nice difference in punch and not a huge huge difference, but a noticeable difference, in price. Try to keep the ouput voltage from minimum 16V to max 24V.
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Like I mentioned earlier, about the pre-amp, I want to avoid switching the inputs. I want to be able to mix inputs (maybe even surround inputs) together so I can, for example, play Halo and listen to music from my Ipod or computer. With the creative card I have (and it's digital input) I could presumably do so on the computer, but since Creative has horrible, horrible support such a function has been disabled since I bought the card.
I suppose you could switch two inputs "ON" and have a volume pot for each input. GIO does this make sense? I think it could work fine for your Halo plus music option.
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I looked at that and $800 seems very accurate. The enclosure/heatsinks/transformers alone are going to hit at a minimum of half of that cost. Enclosure probably around 70, heatsinks about the same, transformers maybe 80 each for the biggies and 30 for the little guy. My estimates are probably accurate but I tend to shop for best price ALL the time and find deals. Heatsinks can really add up if you cant find a good ebay deal on them.
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From 41hz.com, the AMP9 (4 channels, 50W@8ohm) is close to what I want to make, but I think compared to what I'm used to that might end up being a little weak.
50W is going to be great per channel on almost any speakers. The commercial marketers like to WOW you with high wattage that is either unnecessary or NOT there. 50W is not weak by any means.
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The folks at 41hz seem to be fond of Tripath chips? I know nothing about what chip is what and where to find them, but I'm thinking I'd like to buy the parts separately from the PCB because I think the kits might be a bit of a rip-off? Unless I'm wrong and the amp chip itself is quite expensive, I don't see how a couple of capacitors (even the bigass 10,000 microFarad caps can't be more than a buck or two a piece??), transistors, etc. can add up to $80. Given the power I want I think the 41hz AMP10-BASIC sounds ideal, and I'd want to buy 3 of them to power all 6 speakers, but I'm heasitant to blow the $240 just yet before I totally know what i'm doing.
Hes fond of them because he is good at designing around them and because the other chips that are popular have audiosector and chipamp already doing a better than anyone else job at designing for them. I think a lot of the DIY kit guys try not to step on each others toes since there is not a lot of money to be made selling kits to a very small public.
The chips are not expensive and the caps can be had for 1.99 each 12,000uf 50V at apexjr.com. Best deal on the net per microfarad.
With a kit you really dont have to know what you are doing. You just have to be safe. $240 is a good deal for that much power and that many channels. You will spend that much in time and frustration doing it any other way, however both ways will be fun and rewarding and I dont think that even if you were as frugal as I am that you could get away with less than $240 for that many channels including pcb boards.
Remember that the AMP9 kit does NOT include power supply. You can either use two car batteries to get 24V and recharge them regularly or you can build a power supply which will NOT be cheap even building it on the cheap. Lets see...
If you go with probably the least expensive toroids I can find you would use
http://www.antekinc.com and pay about a penny per VA.. Thats cheap cheap cheap. So lets say only $44 for each of 3 AN4218 toroids. Thats 400VA each toroid with double secondaries from each for one set of secondaries for each channel. so $132. You could go with one AN8420 for $84 but it has 4 secondaries. Not a big problem, just a preference for one set of secondaries per channel.
We need caps. At 1.99 each for 12,000uf lets say 16 of them for 32 plus shipping. Luckily you will be buying LM3996 from the same guy. Saves on shipping and overall cost. 6x3.50 gets 21. Rectifiers are 2.50 each from apexjr so we need 6 of them for $15. Various resistors will run a few more dollars and some wire is another few bucks.
On/Off switch maybe $2, plug $2, Fuse holder $1.50, snubber caps for power caps and rectifiers add approx $10 could be lots more or less depending on what quality caps you use, but $10 is nice number

Enclosure... maybe build your own but I have been using wood enclosures and if I were using metal I would probably not have so many grounding problems. Premade metal enclosure. I think you could go to the local electricians store and get a switch box that would fit all of this, but it wont be pretty. However, you might get away with $50. Other than that probably upwards to $70-$100 for something pretty to house 3 transformers and closer to $50-$70 for one.
So lets guess that if you do most of this yourself you are into ~$225 for power supply without the enclosure. The kits are dependent on the supplier but we can guess that you are at a minimum of $240 and thats a fair price. You dont need much in the way of heatsinks for each chip, but we need to remember that the kits do not supply enclosures, switches, wires, fuses in most cases, RCA inputs and outputs, speaker outputs, or heatsinks.
So it is entirely possible to run into about $600 for 6 channels.
Somebody correct me if you think my numbers are crazy. They sound fair to me.
Ri