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Old 27th April 2008, 04:53 PM   #591
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Quote:
Originally posted by chalkandtalk
Russ,
Dou you have any idea when you will be taking orders again for the Buffalo?

Will there be some sort of kit which will enable the digital volume control to be used, in the next round?

Dreaming even more: Do you forsee a module which could go before the DAC which will filter the digital input into 2 by 4 to act as a digital crossover?

We should have the new boards ready to go in a few weeks.

We have a seperate project call "Femto" which is a sort of modular USB programmable microcontroller application.

We will have a module into which the FEMTO plugs. That module can be used to control the volume etc on the Buffalo and a drive a VFD display. It is being designed to be flexible to be used with more than one project.

This is the project we had one called "Uber" controller. Perhaps it will still be called that.

There will also be a module to drive Joshua Tree and Darwin boards.

I will have to think about doing some DSP stuff. So much to do, so little time....
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Old 27th April 2008, 04:57 PM   #592
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Quote:
Originally posted by lfat
Hello Russ!

Could You describe the "sound" of the Buffalo: Rather analytical like the PCM1794 family or rather smooth like the WM8740, or totally different?

regards

Georg

Georg,

I am not good at subjective speak. The final sound of the Buffalo DAC will depend very much on how it is configured and what I/V stage is used.

I can say I am very pleased with the result using the "IVY" module for I/V.

It sounds spot on accurate to my ears, yet is not fatiguing. It is very engaging and alive. That's about the best I can do.

Cheers!
Russ
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Old 27th April 2008, 05:33 PM   #593
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It all sounds brilliant.
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Old 27th April 2008, 05:39 PM   #594
4real is offline 4real  Netherlands
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I'm actually hoping the Sabre will not sound at all
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Old 27th April 2008, 05:52 PM   #595
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Quote:
Originally posted by Russ White



I can say I am very pleased with the result using the "IVY" module for I/V.

It sounds spot on accurate to my ears, yet is not fatiguing. It is very engaging and alive. That's about the best I can do.

Cheers!
Russ
The Ivy looks like a nice clean circuit. However, there is no post filtering after the opamps and this is not usual. Have you measuerd the spectrum directly from the balanced outputs.

And how sensitive is the opamp output to imbalance in the +- supply voltages?
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Old 27th April 2008, 06:21 PM   #596
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Quote:
Originally posted by fmak


The Ivy looks like a nice clean circuit. However, there is no post filtering after the opamps and this is not usual. Have you measuerd the spectrum directly from the balanced outputs.

And how sensitive is the opamp output to imbalance in the +- supply voltages?
The filtering is done at the THS4131. No other filtering is required, but it would be easy to accomplish if one wanted it.

The the output of the THS is centered at GND thanks to the VOCM being set to GND. So a difference in the positive and negative rails will not have much if any effect.

The module well be measured for THD and DNR along with the Buffalo.

But after many hours of listening to it I would not change anything right now. It sounds excellent. As they say, the proof is in the pudding, and I like the pudding a lot.

Cheers!
Russ
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Old 27th April 2008, 07:53 PM   #597
NeoY2k is offline NeoY2k  France
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Quote:
Originally posted by 4real
Nicolas,

Do you have any idea how large the PCB is going to be? And what is the IVY going to look like?
I'm doing my best to fit it in the less space possible.

However I'm more and more thinking of making it the smallest - just the DAC, pin headers on each side of the chip, and connectors for everything.

Then have a sepate board for the IV, another for the clock, another for SPDIF input, and a last one for power supplies.

That would allow anyone to improve it the way he likes as I receive a lot of emails from people wanting slightly different things.

So you have everything in a kit, you don't have to take everything, and if after testing there's something you don't like, well, just disconnect it and plug your own.

It should take less room than everything on a single PCB.


Quote:
Originally posted by 4real
I'm actually hoping the Sabre will not sound at all
I'm hoping so too


However, I'm designing the board and still have a few questions (Dustin and Russ... If you could answer...).

- There are 6 power supply rails: 1.2V and 3.3V, for Left and Right, and Digital +1.2V and 3.3V.

I see the interest of using separated Digital and Analog power supplies.
However, if I use separated power regulators for Left and Right analog supplies, can I expect any improvement (channel intermodulation) or does it makes no sense considering how the chip is made inside?

- I'd like to put voltage regulators on a separate board - for easy debugging, testing other ones...
But it takes them quite far from the chip. May that cause any problem? Of course, Caps will be just right on the pins of the DAC.

Thanks,
Nicolas
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Old 28th April 2008, 05:00 AM   #598
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Quote:
Originally posted by Russ White


The filtering is done at the THS4131. No other filtering is required, but it would be easy to accomplish if one wanted it.

Russ
I understand this. However, fc of 192k seems very high and 50k to 96k is more normal with hifi equipment.

Your website seems to say that there are pads for adding filtering. Is this right?
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Old 28th April 2008, 08:07 AM   #599
4real is offline 4real  Netherlands
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Quote:
Originally posted by NeoY2k
[B]
However I'm more and more thinking of making it the smallest - just the DAC, pin headers on each side of the chip, and connectors for everything.
That should be the best option, I guess.

Quote:
Then have a sepate board for the IV, another for the clock, another for SPDIF input, and a last one for power supplies.
Since people will either use it in stereo or in (x%2) ==0 mode, I guess a stereo IVY board should be just fine. You could then simply stack them without needing to much space. mono IVY's should also be fine of course.

Quote:
However, if I use separated power regulators for Left and Right analog supplies, can I expect any improvement (channel intermodulation) or does it makes no sense considering how the chip is made inside?
I you make an external PSU anyway, you could simply leave this descision to the users of the board Just make some jumper to tie the stuff together or leave it separate.
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Old 28th April 2008, 09:00 AM   #600
NeoY2k is offline NeoY2k  France
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Quote:
Originally posted by 4real


That should be the best option, I guess.



Since people will either use it in stereo or in (x%2) ==0 mode, I guess a stereo IVY board should be just fine. You could then simply stack them without needing to much space. mono IVY's should also be fine of course.



I you make an external PSU anyway, you could simply leave this descision to the users of the board Just make some jumper to tie the stuff together or leave it separate.
Yes, I'll put a stereo IV for people wanting stereo, and a 8ch I/V for people wanting 8ch - won't cost me much time to copy/paste it 4 times and connect +VCC and - VCC xD

"PSU" board is just regulators, in fact, just improved ones - a regulator, a transistor, somes resistors and caps.

You'll have to provideat least +1.2 and +3.3 power rails - say hello to Russ's power supplies . If separate regulators are not enough for you, well, you can buy 3 "2 voltages" power supplies.
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