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Old 27th April 2010, 03:13 PM   #531
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I have searched the forums but could not find an answer to this:

On the IVY, when used with Buf II, should I use the supplied 2.20K resistors for R32-R35?

I am asking because the manual states "n/a" as the value for R32-R35. From that I got the feeling they could/should be ommited. But from the pictures showing the stacking option, one can see the resistors in place.

Looking forward to listen to it. Great fun to assemble for a novice DIYer.

Cheers from Norway
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Old 27th April 2010, 05:31 PM   #532
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Default SPDIF problem please help

I do it the setup to configure the B II for SPDIF: changed the input selector in the pcb & used GND for ground & SPDIF for signal & the Led to indicate locked don't lit & the B II don't sound, both Leds on the top of B II are lit, until today the unit was going on very well with setup I2S but now I need to change the setup to SPDIF to connect the hiFace M2Tech 24/192, please help?
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Old 27th April 2010, 05:34 PM   #533
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Quote:
Originally Posted by Naturlyd View Post
I have searched the forums but could not find an answer to this:

On the IVY, when used with Buf II, should I use the supplied 2.20K resistors for R32-R35?

I am asking because the manual states "n/a" as the value for R32-R35. From that I got the feeling they could/should be ommited. But from the pictures showing the stacking option, one can see the resistors in place.

Looking forward to listen to it. Great fun to assemble for a novice DIYer.

Cheers from Norway
Mine is both resistors soldereds R32-R35 & is going on perfectly in balanced mode.

Cheers from Spain.
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Old 28th April 2010, 03:09 AM   #534
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Quote:
Originally Posted by Naturlyd View Post
I have searched the forums but could not find an answer to this:

On the IVY, when used with Buf II, should I use the supplied 2.20K resistors for R32-R35?

I am asking because the manual states "n/a" as the value for R32-R35. From that I got the feeling they could/should be ommited. But from the pictures showing the stacking option, one can see the resistors in place.

Looking forward to listen to it. Great fun to assemble for a novice DIYer.

Cheers from Norway
No You don't need them unless you are using the IVY III with the Opus or similar voltage output DAC. but they won't cause any harm either.
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Old 28th April 2010, 03:11 AM   #535
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Quote:
Originally Posted by merlin el mago View Post
I do it the setup to configure the B II for SPDIF: changed the input selector in the pcb & used GND for ground & SPDIF for signal & the Led to indicate locked don't lit & the B II don't sound, both Leds on the top of B II are lit, until today the unit was going on very well with setup I2S but now I need to change the setup to SPDIF to connect the hiFace M2Tech 24/192, please help?
Try another source to be sure that is not the problem.

And please post this sort of thing on the support forum. Not here.
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Old 28th April 2010, 11:16 AM   #536
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I have tried other source (dvd instead pc), now sounds cut off & locked Led blinks lit & don't lit.
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Old 28th April 2010, 11:19 AM   #537
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Quote:
Originally Posted by Russ White View Post
Try another source to be sure that is not the problem.

And please post this sort of thing on the support forum. Not here.
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Old 28th April 2010, 03:00 PM   #538
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Ok posted in the support forum, thanks in advance for quick help.
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Old 4th May 2010, 11:24 PM   #539
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Quote:
Originally Posted by Russ White View Post
FWIW I did try some low value impedances, (10, 21, 100, 221R). THD was significantly impacted even with 10 ohms.
This is very interesting, but something needs to be clear to me, when you say 10 Ohm, can this be connected straight to ground or to 1.65V? If there is an offset voltage of 1.65V and connect 195R + 10R to 0V (ground potential), then there will be 8mA going through that 10R (and of course 80mV across the 10R), would the DAC work OK under those circuimstances.

I seem to have seen elsewhere on one of the other forums, somebody using a transformer where the primary centre tap is grounded. It did not show the DC resistances of the transformer's two primaries, but I assume not that high. It was said to work. So the DAC works OK with virtually a real short rather than into a virtual earth floating at 1.65V as suggested by ESS using opamps?

My reason from inquiring is that I would use a differential Low Z I/V into a non-opamp diff amp and not having to float I would make a direct-coupled circuit to bring up to 2VRMS and no coupling cap needed to isolate 1.65V - it would add great simplicity using an existing circuit we have developed, very low noise and its gain can be set to 2VRMS. Indeed 1R+1R I/V Z is workable.

Appreciate your comments.

Cheers, Joe
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Old 4th May 2010, 11:44 PM   #540
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Quote:
Originally Posted by Joe Rasmussen View Post
when you say 10 Ohm, can this be connected straight to ground or to 1.65V? If there is an offset voltage of 1.65V and connect 195R + 10R to 0V (ground potential), then there will be 8mA going through that 10R (and of course 80mV across the 10R), would the DAC work OK under those circuimstances.

Appreciate your comments.

Cheers, Joe
Hi Joe,

It makes little difference the voltage at the end of the impedance.

The problem is not one of offset but of modulation.

I have a discrete output stage (no GFB) I just built and am testing for Bufffalo II.

It is called Legato. It works wonderfully. It is a common base trans impedance amplifier followed by a CCS feed emitter follower as a buffer. Very much like a D1 but with lower noise.

So far it is sounding wonderful. The distortion is quite low. Not quite as low as the IVY-III but, quite low indeed for having no global feedback.

Its DC bias at the virtual ground is adjustable. It is easy to get it right at AVCC/2 which is indeed optimal at least when no feedback is employed.

The input impedance is less < .2R (I am not sure exactly yet could be much lower).

Cheers!
Russ
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Last edited by Russ White; 4th May 2010 at 11:52 PM.
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