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#1 Posted : Saturday, March 6, 2021 10:51:58 PM(UTC)

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Joined: 5/9/2008(UTC)
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Well, it's been a while. Seems my last post here was over 10 years ago!

Way back in the before time, in the long long ago, I built the original Buffalo DAC. One of the very first batch, if I'm not mistaken. It has served me extremely well, basically being in constant usage for almost 13 years. But I've got the itch. A bad case of upgraditis to bring it into modern times. And I think trying to drop in a IIIsePro-28 module is the only cure.

For a bit of background, my Buffalo module receives I2S from the original CS8416 SPDIF MUX. That in turn switches inputs between a 3rd party USB module, Toslink and Coax. All of this input/DAC side is fed by two LCDPS (i.e., four separate power lines, with separate VD and VA to the Buffalo) in the 5-6.6V range. The line stage is an IVY III set to 2VRMS output. It is powered by a Placid BP 2.1.1 (±15V) with the stability fixes made as per this thread. My problem is that after being out of the game for so long I feel like a noob all over, so I'm hoping to get a sanity check on what I can do as an absolute minimum to upgrade.

It seems like the IVY III is still a perfectly cromulent output stage, with no modifications required...? If so, I'll leave well enough alone.

It seems like the I2S input from the SPDIF MUX is still going to be AOK...? If so, I'll leave well enough alone.

What really seems to have changed, and for which I am not sure what to do, is power. Instead of separate VA and VD at reasonable currents, everything on the new modules all comes in through one connector, which is way too much for a single rail on the poor little LCDPS. So what are my options?

My first thought was whether it is possible to feed a Buffalo's regulators from two different power lines? If possible, this would be the cheapest solution. It seems like I could supply VD at the main terminal to feed DVCC, AVCCL, AVCCR and VDD_XO for a total of ~250 mA. Then I could run a separate power line directly into the VDD regulator rather than connect it to the VD supply main board.

The other option seems to be to replace my stack of two LCDPS with a single Centaur, and use that to power everything. This is less preferred; module cost, small amount of casework, noise from MUX, Toslink and USB modules potentially interacting with the DAC, all make it a bit less desirable.

I'd love to hear any thoughts!
#2 Posted : Saturday, March 13, 2021 10:21:59 PM(UTC)

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