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!

4) they run off of ac and it's not just a simple transformer inside that would could bypss with a dc psu.

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

Actually, there are a few people who have converted these to DC and are currently running them in their cars and competing rather successfully with them.

I'm speaking of the Drive Rack specifically.

this just doesn't settle well with me. It might work fine for others, but the fact that you have to purchase multiple units, bothers me...more components = more possibility for problems and interference.

btw - what is this guys (Doug) last name?

does it start with a W?

The line level out of the stereo-link is 2V rms, the standard line level out for home audio systems (eg CD players). The computer sound card standard is 1V rms.

For clarification, the DAC uses 3 power supply voltages: 3.3V for the digital, and +/- % for the analog section. There are on-board regulators for each of these.

We will be introducing a high-end audiopile version within a month that will have a more robust power supply running at +/- 8V, and the headphone output will be capable of a little more than 4 V out, but the cost will also be quite a bit more.

Hope this helps.

I'm not sure what you mean by a four channel version. If you mean 4 channels of decoding (quadrophonic rather than stereo) I don't think it can be done, but I also don't know of any recordings that are quadrophonic since the early 70's. If you mean having 2 sets of outputs, you can simply parallel the outputs and connect two wires coming out of each channel. You could also use a Y cable of some sort.

As for running 2 at a time, I doubt you can run 2 usb soundcards at once. To do it, you would need to configure something at the computer itself. Also, you would need to have some extra current as this card, because of the opamp, buffers, and dac will not play well with other usb devices. The TDA1543 draws about 50ma, the amp portion will probably draw a little less than that, and the pcm2707 will draw a little. If you consider that usb can supply 500mA at 5V, that this soundcard is converting that 5V to 14 or 18V at about 70% efficiency, this means that you only have about 125 to 150mA to work with. It should be fine for one, but I doubt for 2.

Doug

well, the common setup in car audio is to have a set of outputs for the front door speakers and output for the sub. (acutally ther are another set for the rear speakers, but we arent concerned about that. Our problem is that we'll need these outputs at 4volts and also to cross them over on the software side of things (that we would have to take care of). if we split them off with a y-cable then we'd be sharing the power to each input, effectively cutting the voltage in half (is my hypothesis correct?). we could always just build an x-over after the amp but before the speakers but we were trying to have the cleanest/streamlined solution as possible.

No, the 2 voltages in parallel are equal. However many outputs you put in parallel, they will all have the same voltage across them.

However, you can only draw so much current, and if you go into 2 inputs from one output, the amount of current that can be drawn for each output is cut in half. However, the buf634 can provide a ton more current than you will ever need (about 250mA), and you will reach the limits of the usb long before you begin to stress the buffer.

The software crossover would not be possible, however. My advice would be to use a cap (in parallel) and a resistor (in series) to make a low pass filter on one of the parallel lines out. Way less work and sounds better too.

-d

Hello Scott,

Sounds like a cool setup. We are planning on adding a "bass management"
feature to our console which would probably be able to do what you're
looking for. But, that is a long ways in the future. We really haven't
had any demand for something like that. Here are a few other
possibilities that come to mind: If you're just playing out of Windows
Media Player, they have some built in EQ and you might be able to find a
plugin to do what you're looking for. I'm not aware of software that
does exactly what you're looking for. But, you might be able to use
standard recording software with "rewire" support to pipe audio into the
software, filter the channels and pipe it out the sound card. You might
also play out of our digital output, loopback into the digital input,
record into your filter software from the digital input and play out the
analog output.

Sorry we aren't aware of a simple way to do what you're looking for.
But, there must be a way to make it work! Layla or Gina3G will both
work for everything described above.

> sorry, me again.
>
> one last question. what is the voltage output on the balanced outputs?
>
> thanks,
>
> scott

Approx 5.75Vrms

Your laptop should be OK for this application.

Thanks for your inquiry.