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Old 13th November 2008, 05:08 AM   #11
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Sorry, to many things going on at once. I had it confused with another post on passive i/v. I am still awaiting the Buffalo.
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Old 13th November 2008, 05:16 AM   #12
Variac is offline Variac  United States
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I'm just interested in various options for a I/V stages that will work with the Buffalo DAC. Not necessarily Pass ones. Certainly balanced though.
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Old 13th November 2008, 07:18 AM   #13
Yunick is offline Yunick  Sweden
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As a Pass fan I would also like to have a Pass circuit in my DAC

As is, it works great if your next stage can take the output swing. I have it mated to a F5 and it sounds good.
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Old 13th November 2008, 11:40 AM   #14
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I too would love to try this as an output for my buffalo - to be honest though I lack the knowledge required to suggest changes and so on. Can the buffalo be modified to put out the right amount to suit the D1?


Anyway, someone back up the thread referred to a group buy for the D1? Where would that group buy be? - I can't find it here?


Fran
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Old 13th November 2008, 11:58 AM   #15
Yunick is offline Yunick  Sweden
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Hi Fran,

The groupbuy finished a few weeks ago, sorry. The layout was made by Zei.

I have had mine playing for a few days according to the original schematic and it do sound good to me. only the output is a bit high thou.. I'm sure there is alot more to tweak to get opimal performance.. Russ have tried a similar circuit called Haiku. He talked about "input bias" should be 1.65V. But I too have not the knowledge to do this..

What do you use today as I/V, Fran?

Best regards
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Old 13th November 2008, 02:29 PM   #16
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I'm using a TP IVY module. Standard TP supplies. Just would be intereseted in trying other IV options - I have a hunch that this DAC can supply much more. Nothing more than a hunch, but I'm willing to build stuff to try it out.

Fran
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Old 13th November 2008, 02:54 PM   #17
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Quote:
Originally posted by Yunick
The schematic can be found here

Khundude, what resistor did you refer to?

Quote:
Originally posted by Variac
I'm just interested in various options for a I/V stages that will work with the Buffalo DAC. Not necessarily Pass ones. Certainly balanced though.
Here's a thread where I sim'd the standard D1.

http://www.diyaudio.com/forums/showt...59#post1329559

-David
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Old 13th November 2008, 07:03 PM   #18
Yunick is offline Yunick  Sweden
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Quote:
I have a hunch that this DAC can supply much more. Nothing more than a hunch, but I'm willing to build stuff to try it out.
Me too

How do you like the IVY module? Have oy also tried buffalo in voltage mode?


Quote:
Here's a thread where I sim'd the standard D1.
Thanks!

I understand that you have experimenting with alot of DAC chip and I/V stages. What is your favourite combo so far?

Best Regards
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Old 13th November 2008, 08:07 PM   #19
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Quote:
Originally posted by woodturner-fran
Can the buffalo be modified to put out the right amount to suit the D1?
It's a wee bit easier to mod the D1 than the DAC.

The D1 should be adaptable to most any DAC current output, you probably just need to tweak the resistor values. The IRF610s aren't wimpy little FETs and could handle more current if need be (properly heatsinked). The lower resistors (R26/R33) control the current bias (~9ma). The upper ones (R27/R34) control the voltage gain. The combo of the upper and lower resistors sets the DC voltage bias point (~15V) of the input to the voltage followers (Q2/Q5) (VOL+/VOL-). I'd probably try to keep that 15V bias point.

So, if the Buffalo puts out twice the current of the PCM63 of the original D1 (I don't know much more the Buffalo puts out) then to cut the gain in half, cut the upper resistors by half, to 750. If that's all you do your VOL+/VOL- bias point becomes 22.5 volts. To lower that back down to 15V cut the bottom resistors by half to 1.65K, which will raise the current bias to 18ma.

Don't know how it will sound, but it seems Nelson tends not to object to more current through a FET.
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Old 14th November 2008, 12:09 AM   #20
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No, I haven;t tried it in voltage mode. The IVY is good - and better than just good when I added in the 10nF caps. That was what opened my eyes to what was possible with this DAC.

I will find out a bit more about the voltage mode and have a listen. I'm using it single ended so just need to sort that out and then I will listen in. I believe I need to add a resistor somewhere to make it go to voltage mode. Have to research this as I don't know much about it.


Fran
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