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Buffalo III - SE

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No - you need to use one or the other. The simplest solution if you wish to use an external clock is to not install the supply for the clock (trident).

I forgot what clock you are using, but doesn't the 957 have a hi z disable pin? It would seem straight forward to implement that feature as a DIY- simply place a grounding switch flip-flop between disables. One would have to swap out clocks however.
 
Not really a Buffalo question bit it is related...

I'm building a Buffalo SE with Placid HD and Placid HD BiPolar
Started with the Placid HD BP. Manual says about the trimmers: Measure resistance between the two outer pins. (pin 1 and 3 in my picture).
I have don that but the resistance does not change. (stays 9.5K). Trimmer is not installed on the PCB. What am I doing wrong here?
 

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On my...

very slowly progressing (in no hurray, as I am waiting for the new TPA USB interface to complete the project) B-IIIse build I went ahead and installed a low profile socket for the oscillator Trident on the board. This DAC will be built up first on MDF for fine tuning and proof of concept, so I can easily listen in both synchronous and asynchronous modes. With B-II right now I am almost certain I prefer synchronous clocking, but being able to make easy comparisons should help me to be sure.
I must say, it is tempting to go with async operation, just because of the higher flexibility this offers. I just finished upgrading a DAC I built for friend with the B-IIIse board/new Tridents, and set him up with an I2S input (via an LVDS/HDMI board from K&K audio) and SPDIF, with a simple rotary switch for input select on the front panel. I must say the B-IIIse provides a simple and elegant solution for those wanting an I2S and SPDIF input.
 
The value of the pot won't make any difference.

The pot just forms a voltage reference which is read by an ADC. It is the DAC itself that does the attenuation digitally.

The attenuation is a linear progession (as the pot is linear) from 0db to -63.5db - but note that decibels are a logarithmic scale. :)

To change the range would require custom firmware, or an external way to manipulate the reference voltage. :)

You could also perhaps use an anti-log pot and/or adjust the output level of the output stage.
 
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The value of the pot won't make any difference.

The pot just forms a voltage reference which is read by an ADC. It is the DAC itself that does the attenuation digitally.

The attenuation is a linear progession (as the pot is linear) from 0db to -63.5db - but note that decibels are a logarithmic scale. :)

To change the range would require custom firmware, or an external way to manipulate the reference voltage. :)

You could also perhaps use an anti-log pot and/or adjust the output level of the output stage.

Thanks, maybe I will go for some (sort of) gearbox solution.
A multiturn linear 10k pot would work right ?

This one maybe http://se.farnell.com/eti-systems/mw22b-3-10k/potentiometer-3-turn-10k-ohm-0/dp/1307124
 
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I finally finished by Buffalo-IIISE. The enclosure is really too small (11.6" x 9.5" x 2.5" inside dims) for good separation between the analog boards and the power supplies, but the hum levels are far below audibility. Good enough.
 

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Joined 2001
Thanks, maybe I will go for some (sort of) gearbox solution.
A multiturn linear 10k pot would work right ?

This one maybe MW22B-3-10K - ETI SYSTEMS - POTENTIOMETER, 3 TURN 10K OHM | Farnell Sverige

Reverse-log pots are not common, but you could use a (normal) log taper pot and hook it up backwards. Just remember that CCW increases volume. :)

Alternatively, you could add an external resistor in series with the ground end of your existing linear-taper pot. This prevents from turning the volume all the way down, but that might not be a problem. If you use a 10k resistor with your 10k pot then your volume at max CCW will be what it is now at 50%.

Cheers,

Dave.
 
Another alternative is a resistor in parallel between the wiper and one end of a linear pot as shown in this article: Potentiometers (Beginners' Guide to Pots)

Reverse-log pots are not common, but you could use a (normal) log taper pot and hook it up backwards. Just remember that CCW increases volume. :)

Alternatively, you could add an external resistor in series with the ground end of your existing linear-taper pot. This prevents from turning the volume all the way down, but that might not be a problem. If you use a 10k resistor with your 10k pot then your volume at max CCW will be what it is now at 50%.

Cheers,

Dave.
 
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