Thread: 1/3 Octave Software EQ

Originally Posted by scott_fx

ON AN UP NOTE! i am in communication with a guy who is designing a usb dac with 4v outputs. I'll keep you posted.

oooo - details?

http://www.dbxpro.com/

I honnest to god do not know why I didn't post this earlier....I feel incredibly slow right now...lol

it isn't cheap, but it's a better piece than the 700...but quite a bit bigger, and a lot more expensive...but it comes with software as well...

Originally Posted by Quack

• Muse Research's Receptor - a piece of hardware that accepts VST plug-ins. Thought this was interesting because it shows that people are trying to do the exact opposite of us...process the sound off the computer. Might be controllable from the PC and would take on all the processing load.

Did you guys even look at this? Seems very similar to the productd in Red's last post. It's got spdif in/out and is designed to accept vst plug-ins (read limitless EQ, crossover potential depending on the design of the plug-in). And, you can control it all from your screen. If you're thinking about going outboard with your processing, you may want to take a closer look.

i'm curious though, if we get a quaility line driver with the m-audio or whatever, and use a software eq (total cost seems to be about $700 for those to together), why in the world would a mom all in one solution cost more than $2-$3K???

Also scott, way cool job man!

ok, bothe those solutions look really cool but I'm not sure i'm willing to dump 1-2 grand into my system since: 1) i dont compete 2) i have a convertable (noisy) 3) i have a built engine, headers, high flow cats, and straight pipes (LOUD) 4) they run off of ac and it's not just a simple transformer inside that would could bypss with a dc psu. they probably run about 38v dc after the transformer or have a complex arrangement of regulators that give it a wide range of voltages. if anyone needs proof i can supply responses ive gotten while looking into hardwiring similar rack mounted x-overs ...so me being selfish I'm exploring something a bit less expensive. even those have balanced outputs which would rock (for me)!


back to the non over sampling usb dac. The gentlman that i've been talking with ok'd me to post this to you guys:

Hi there, The standard NOS DAC using a TDA1543 has about 1.5V output at best (TDA1545 has something like .5V). You can parallel the chip which, since they output current, increases the voltage. The problem there is that they will draw a lot of current by the time you have 4V. They also get really hot. However, if you have the current to give and a fan you can stack enough chips to meEt the 4V requirement.

However, I may have a different solution for you. I am working on a NOS USB DAC that also has a volume control and a gain stage. The whole thing is powered via usb so there is no need for a power supply. The gain stage uses an opamp (like an OPA2132) and a pair of BUF634 buffers. I use a pair of either 9 or 7V DC-DC converters to get +/-18V (or +/-14V) from the USB jack to power the opamp. The effect is that you should be able to get a very high output with 4V not being a problem. If you didn't want a volume control, you could just use some resistor dividers in its place for always on full. Then you would just set the opamp's gain where you want it to get 4V out.

Anyhow, I am almost done with the board design, and I am hoping to get some prototype boards made in the next couple of weeks. If all goes well I'd like to sell a few after that. You can see the schematic and a preliminary board design at http://headwize.com/ubb/showpage.php?fnum=3&tid=6233

Oh, I have no plans for doing anything with balanced output. I'm a single ended triode kind of a guy. There are a few diy dac's with balanced output floating around, though I don't recall seeing any for usb.

Doug

and

What I am hoping is to be able to sell a board + TDA1543 + Nichicon ES coupling caps + I/V resistors for around $20 (or less perhaps) This depends in part on getting a large quantity of TDA1543's, but I think it should be possible. The volume pot can be found for about $20 at a number of places (percyaudio.com sells Nobles that will fit for $20, and the Alps "Blue" can be found at http://www.tangentsoft.net/audio/shop/ and http://www.amb.org/shop/ among other places) and I'll also probably make room for a Panasonic that can be found at DigiKey for about $3. The rest of the parts can be found at DigiKey, and I would guess that it will cost about $60 for the parts (the DC-DC converters are expensive.) So, about $100 for the whole project, though it could be done for about $80, and high end parts could send it to $150 or so.

So there you have it... i think hardware wise we are getting close. keep in mind these boards have only two outputs so with most of us, we'll need 2 boards...getting us the $300 mark...not too shabby

i mention 2 boards because most of us will be running sub/front systems. for those that aren't competing and/or want rear speakers you would probably have to either purchase 3 kits -OR- split the signal from one kit to go the rear and sub (not sure about sq penalty) -OR- run the rears off of a soundcard output while using the usb dacs for the fronts and sub. actually, depending on your ultimate goals you could probably get just one Usb DAC for the front speakers and then use the conventional soundcard outputs for the sub and the rear speakers. so there are a lot of options out there.

Originally Posted by Quack

I posted this in the Frodo forum (since I use FP). Frodo's been silent lately, so I'm not real hopeful that it will get much attention.

i liked your post so much that i stole it and reposted it in the centrafuse forum :-)

Originally Posted by scott_fx

i liked your post so much that i stole it and reposted it in the centrafuse forum :-)

Great...if you get a quick, positive response, I may just switch over to Centrafuse. I think Frodo's got a lot going on right now (read: less development/support).

vst plug-in support?

it is a quick and positive response

Wow...with response times like that, I may be converting over soon

Originally Posted by scott_fx

vst plug-in support?

it is a quick and positive response