Advise on entire DIY stereo system

[prattems]

I'm considering building a complete DIY stereo system. My main goal is to have decent sound with little money. I've listed my signal chain below, with motivations for choices. I really appreciate any advise you have about these ideas:

1) A Linux PC with decent sound card (M-Audio Delta 44 now) as source (CD player, WAV files), and as an active crossover and room correction using bruteFIR. I want to use a digital crossover because I am not smart enough to build a physical one properly, I understand that the FIR filters will sound the best, and I like the idea of tuning the XO after the speaker is built. I want to use the PC over a piece of hardware (e.g., the behringer XOs) because it's cheap, and it eliminates both an A/D and a D/A step. The ability to do room correction is also nice.

2) Chipamps. I'd like to use the stereo LM1875 for the tweeters ($45) and the stereo LM3886 for the woofers ($70). I think I can use an Avel Y236651 250VA 18V + 18V transformer for each one ($55 each). I'll put a volume knob on each, and yolk them mechanically for volume control. Any better ideas are very welcome.

3) 2-way bookshelf speakers. I'm thinking a sealed cabinet with sloped front with Usher 9950-20 tweets ($60 each) and Usher 8945P 7'' woofers ($110 each). I prefer the sound of sealed, and these could end up on a shelf in a corner. I like the sloped front b/c it looks cool. I choose the drivers based on reviews, and so would love other ideas in this price range. Also, I will put a cap in line with the tweeter to prevent low frequencies (e.g., <500hz) from blowing it. My thought is that, since the active XO will be set around 1000hz, the cap should have literally no effect on the sound.

4) The Behringer ECM8000 reference mic ($50) into a preamp (I have an ART Tube MP) back into the soundcard for XO tuning and room correction measurements.

That's it. I really appreciate any advise, component suggestions, and especially warnings (e.g., if this will end up being a $1000 boombox-sounding piece of junk).

Mike

[planet10]

Mike,

Bugeting for calibration of the mic (i used Cross-Spectrum Labs) will save you a lot of headaches.

dave

[wakibaki]

Nothing wrong with a Linux PC and soundcard as source, if you're confident about getting your choice of soundcard working under Linux, but this can be timeconsuming, and some cards have insurmountable problems. Of course this is also true under Windoze, but less frequently.

I'd go for a high-efficiency fullrange driver (in the US you can get Audio Nirvana with no problems) in a big (or even not so big) box of some description, this not only allows you to use a low-power, cheap amp like the Sonic Impact, you won't need a mic, calibration, x-overs, and you won't need to fiddle around.

Everybody should have a set of FRs. I'm not a tube guy (for hi-fi), but they give you the opportunity to try the tube sound in a low-power lo-cost amp at some time.

Later you can try cutting a bit of the Bass out of the FRs and adding a Sub.

'Course this won't leave you a lot to DIY apart from the boxes, you'll be obliged to listen to the music instead...

w

[WithTarragon]

Well, the reason to go DIY is partly for the joy of it. Saving money is a frequently a dream that does not come true.

If you are primarily driven by getting a low cost system that sounds great, you may want to go for used equipment. If you want, you can always freshen up the caps on the crossover and amplifier.

For instance: a pair of old Magnepan SMGa (or Klipsch Heresy, or your favorite choice) and an old Adcom GFA 545 (or Hafler DH 200, or your favorite choice). Would be less expensive than what you have in mind.

Be careful, however since you will soon get a number of recommendations that will ignore your price point. Take my recommendations with a huge grain of salt since none of us have any idea what your priorities are in terms of sound reproduction.

[lgreen]

I second that, you should not DIY to save money. All of this is going to add up to more than you expect. Do it because its fun and you get something unique at the end. Buying older classic gear (Klipsch, Infinity Kappa, etc...) is far superior if the goal is to save money, and you can resell it later and recoup a lot of (or all) your purchase money. You can diy some mods to satisfy your diy needs. DIY has almost zero resell value so in the end you lose out financially.
.
If you like medium or loud music chipamps will likely not cut it for the bass. However you can power all the chips from the same transformer to save money. I'd upgrade the LM3886 to a "parallel" configured LM4780 at a minimum and this still may not be enough.

[planet10]

I disagree on the those saying you can't save money. If you go with tried and true kit, and have or can amortize the equipment needed on multiple projects (whether audio or not), then a lot of money can be saved.

And there is no price on the beneficial affects of the hobby to your sanity.

I've had a lot of use commercial kit thru here and none of it matches up (well speakers anyway, my addiction of choice). diy amps are hard to match with commercial gera too... sources (TTs & CDs are harder, but mods can certainly push things forward)

dave

[jleaman]

Maybe a minidisp will be good for you to have also

Chip amp's are good start, however once you have the nac and ears for good sound you will always want to upgrade Now the choice may be to think about if you want to replace some stuff after you built it, or buy something good.

P.s Never cheap out and cut corners on amplifier parts it will just bite you in the but later.

Chip amps = good start

[prattems]

Thank you all so much for your input. I agree with everyone that I have underestimated the $$$, but more importantly, I realized that I might not have the patience to work on this project for a year before hearing a single note.

I think I'm on board with wakibaki's advice to go full range. I like commonsenseaudio's "monitor", with the Super 8 Alnico. I can drive them with my Marantz PM7000 until I find/build a tube amp, and can build a sub in the meantime. It seems like I would need a highpass on FR's if using a sub to avoid LF phase problems, but at least I'll have music while pondering it.

Thanks again,
mike

[tpsorin]

I think that your initial idea is excellent. If done right, it will sound fantastic.
Just take care that you have to adapt your crossover for drivers that you use. Not just using generic 4th order.

Power shall be enough with bi-amp. It depends of your listening room ant type of music.

[prattems]

Seriously, thank you tpsorin for supporting my original idea. After looking through the fullrange forums here, I see that a lot of people end up adding a tweeter to them. I am in no way qualified to judge the fullrange endeavor, I just think I'd rather start with a 2-way if that's where many people end up anyway.

This evening I got an old linux box (fedora 9) successfully running. If there are any computer geeks here, I'm using the JACK server as my audio router. I played CDs with my cheapo internal drive, routed the digital output to brutefir, and from there to my m-audio delta-44 card. I verified that it all worked with some PC speakers, and the standard brutefur script that delayed one of the channels. Now I just need to generate the XO config file for brutefir to read and use.

For time's sake, I'v decided to use my Marantz PM7000 integrated to drive the woofers for now (much more power than cheap chipamps, thanks lgreen). The tweeters I'm considering are rated at 10 watts RMS and 15 max, and I'd love to find an inexpensive tube amp to drive them if anyone has suggestions. If not, then I'll build a gainclone.

So all I have to do it find/build a tweeter amp, build some 2-way bookshelves, and I've got an active XO biamped system with room correction options (:

Mike