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Recently, I completed the breadboard for a Buffalo III stereo, which is an intermediate step in the ultimate goal of a Buffalo III dual mono DAC.
The sound is exemplary, and compares very favorably with the two other DACs I have on hand: A Mark Levinson 30.5, and an Audio Research DAC8 (all fed 16 bit/44.1 kHz signals). Each has its strengths and weaknesses, but the Buffalo III does more than hold its own, especially at its price point, even factoring in a reasonable amount for labor.
I have three questions regarding the Buffalo DAC:
1. There is a "pop" through my speakers when I mute or un-mute my pre-amp. I have never noticed this with any of my other source components. The Buffalo is connected by balanced interconnects. The DC offset at the Legato balanced outputs is 0.000V.
2. I have wired my Buffalo III with a volume control and tried to drive my amp directly. The sound was so faint that I had to put my ear to a speaker to hear anything, yet with the volume on the DAC at max the sound through my pre-amp and amp combination is very much in the "normal" range. I had thought that I might be able to skip the pre-amp, but this appears not to be possible with the present configuration.
3. I will want to use higher resolutions than Red Book standard and will implement this by computer using USB (I'm already doing this with the AR DAC8). I had hoped that the higher resolution TPA USB transport would be ready, but I may have to go with an Exa U2I. I have read what seems to be a number of problems with interfacing devices through the Sidecar. Has anyone successfully integrated an EXA U2I through a Sidecar on a Buffalo III dual mono? If so, would you be willing to share the benefit of your experience?
Sincere thanks for your help --
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1. This sounds like a DC problem. Do you have the balanced output ground connected between the Legato and your pre-amp? If so, try leaving it out (just using +out and -out).
2. I assume you are not using an I/V stage for the direct connection (outputs from the Legato). It will solve the problem.
3. Many many people have done this without issue. the problems you have read about recently have been with tweaking the 4-position switch board to trigger the Sidecar. Again, many people are doing it, but you have to use position 1 for the Sidecar trigger, not position 4, unless you do some additional work to turn off S/PDIF auto-detect on the Buffalo (easier to just use position 1, or a different switch mechanism).
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Thanks, Brian, for your very quick reply.
Questi1: Problem 1/2 solved. After the ground is lifted at the Legato output, the pop is gone when mute is engaged, but remains when un-muting.
Question 2: Do I understand correctly that for the configuration to work as a pre-amp, the signal must be taken at the output of the Buffalo III before it goes into the Legato? That would be at one set of the three contacts (+,-, and ground) for each channel, O1-07 and O2-O8.
Question 3: Thanks for your resassurance that this is not a problem. I had planned to use input #1.
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2. No, take the output from the output of the I/V stage, in this case, the Legato.
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2. That is what I did and had no volume. How can I resolve this problem? Thanks!
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Are you wiring the XLR connectors correctly? Pin1: Ground, Pin2: Out+, Pin3: Out-.
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Yes, the pinouts are as you described.
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Do you have the same issue with the SE outputs?
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At this point I have only configured the balanced outputs. I will wire single-ended and let you know. Thanks very much for your very helpful suggestions.
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Are you getting volume control?
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Hello, Russ. Thanks for your interest in this problem. I won't be able to test the single-ended output until the middle of next week. I'll post the results.
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I configured the Buffalo III stereo for single-ended output and I'm getting good output with the volume control (the volume setting is at approximately 1 o'clock) directly into the power amp. However, there is audible 60 Hz hum in both channels with the single-ended output.
I double checked the balanced output directly into the power amp, and have a very faint signal (I have to put my ear next to the speaker to hear it).
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Could you post a picture of your layout, including wiring? Sounds like a ground-related issue.
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A progress update: I assembled a breadboard Buffalo III dual-mono version, and I'm very pleased with the sound. I'm also pleased to report that: Problem 1 from first post: Now there is no "pop" when I mute this DAC with my preamp. It is completely silent. Problem 2 from first post: I have complete control of gain using only the DAC's volume control, so that I can omit my pre-amp, if I choose. I'm very pleased with this possibility. Problem 3 from first post: I built a very nice Windows-based music server which is capable of 24 bit/192 KHz resolution(and I have numerous music files in this resolution that I would like to feed into my Buffalo III DAC), but I need a USB Transport capable of handling high resolution files. I would prefer to keep my system all TPA. Brian and/or Russ, is there any chance that your high resolution USB Transport will become available in the foreseeable future? My next steps are to integrate a pair of Ventus EZs for single-ended headphone output, followed by installation of a USB Transport, and ultimately, the addition of something like a TPA AC-1/AC-2 for remote control. After I'm satisfied with everything on the breadboard, I'll install the components in a cabinet with custom made front and rear panels. Thanks Russ and Brian for making such satisfying and enjoyable products! 
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Hi eseal,
Would it be possible to share all your solutions for the problems you desribed? |
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