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Old 24th April 2008, 12:05 AM   #531
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Default Firmware for volume controlled Buffalo

Hey Folks,

I am very pleased with the volume control of the Sabre DAC. Well I am pleased with the DAC in every regard...

I wrote this firmware to use with my Buffalo DAC.

It is written for Hi-TECH C (free for DIY use with Hi Tide IDE) utilizing an old Joshua Tree controller board I had lying around.

A PCB is not really required. All you need is a PIC16F690,PIC16F685 or PIC16F687 any of those should work fine.

You will also need a 2-5K linear pot with the high side connected to VDD and the low side to GND. The wiper gets connected to AN0.

Anyway the code is pretty self explanatory. RC0 and RC1 are the I2C lines.

Some of you working on Sabre DAC projects may find useful tidbits in it. If you do that's great. If not, well I don't really care.

You could actually use a smaller PIC like a PIC12F675 and it would port very easily. You could even do this with the Buffalo board alone by using a PIC12F675 and keeping one of the switches open and connect the wiper to that switch position output. I may try that myself at some point.

Also it would port pretty easily to an AVR.

I just happened to have this PCB and chip handy.

The volume will track the pot. Its simple, and it works perfectly for me.

Enjoy!!!

We will have the modules ready to roll soon.

Cheers!
Russ
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Old 24th April 2008, 12:07 AM   #532
NeoY2k is offline NeoY2k  France
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MDR, have you heard about the ENSATT?

Bref, I'm in the 5e St Just. Cool xD

I draw the board tomorrow. I'll submit it, if anyone wants me to modify some things...
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Old 24th April 2008, 01:00 AM   #533
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Default Test Rig

Here is the Buffalo in my DAC test Rig. The volume controller PCB is top left. You can see the three wires heading to the front and the pot.

There is an IVY under the DAC.

Cheers!
Russ
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Old 24th April 2008, 02:22 AM   #534
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Default Patch :)

I just noticed that I had a small error in main.c.

In the setup method I was setting the modulator gain register with the mute value.

No bonus points for any of you for pointing it out first

Here is the corrected file:

rename it main.c
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Old 24th April 2008, 02:33 AM   #535
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Hi Russ,

I didn't notice that one. I did notice you are using the slow rolloff instead of the fast.

I did a listening test and didn't hear any reason to change it to slow. As some others have noted in the thread recently, the slow rolloff could result in some alias images.

I didn't do a thorough listen test. Did you set that based on a listen test? I decided to leave it at the default, which is the sharp rolloff beginning at .45 fs
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Old 24th April 2008, 02:36 AM   #536
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Hi Ross,

I have been playing with it back and forth. Between sharp and slow. I just happen to have it at slow right now.

This is partly because I employ analog filtering at the IVY (about 100khz fc). So slow filter curve should not result in too many nasties.

It sounds really great either way and I would be hard pressed to note a difference.

Cheers!
Russ
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Old 24th April 2008, 02:50 AM   #537
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My Brother Ken(Runs a recording studio here in Nashville) is here today and we are listening to 192/24 masters on the Buffalo. Incredibly nice, and he brought a great selection.

One the artists we are listening too is a local Violinist playing Brahms. So sweet and pure it is giving me goose pimples.

But That's not all, he also has some incredible local jazz band with a double bass that sounds like he is slapping it form just in front of the chair. Amazing. When the string is plucked, you hear (or feel) every nuance.

So I can say without a doubt this is the best DAC I have heard, especially for hi-res material.

I am using a 80mhz clock so I can do 192khz SPDIF/AES.

My brother is not leaving until I promise to build him one, of course that was already planned.

Cheers!
Russ
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Old 24th April 2008, 03:22 AM   #538
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To top it all off I just tapped into my keg of home brewed (I have more than one hobby) Foghorn Stout. Wish I could pour you guys a few.

What a great night.

Cheers! (gulp)
Russ
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Old 24th April 2008, 03:49 AM   #539
Cappy is offline Cappy  United States
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Russ,

That beer looks good. I'll take one right now!

I'm up for the "Dustin Challenge":

"1. Sabre in synchronous mode, with very high end transport with low jitter mclk.

2. Crappy transport full of jitter, then let the Sabre do its thing."

But your Buffalo has to support it -- will it have a switch for synchronous mode that takes out ASRC?

In addition to SPDIF, My Empirical Audio Pace Car "transport" also does I2S out with a SuperClock 4 as mclk.

Bill
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Old 24th April 2008, 03:55 AM   #540
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Hi Cappy,

I have to say (modesty be damned) it's a hell of a good beer

Yes the Buffalo will support the "Jitter Reduction - Off" register as a switch. So you can feel free to experiment away with an ultra low jitter source.

As for me, I am perfectly happy with the jitter reduction.

You can disable the on board clock by bringing pin 1 of the XO low, or just omit the XO. And there are two pads next to the master clock for external master clock input.

Cheers!
Russ
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