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Old 6th December 2011, 02:26 PM   #411
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You want the output stage to feed opamps?
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Old 6th December 2011, 09:51 PM   #412
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Originally Posted by leifchristensen View Post
just a claim imo

all of them will probably behave differently in different circuits

best
Leif
No they do not behave differently but the result could be different.
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Old 6th December 2011, 09:54 PM   #413
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I want to use the balanced outputs of the Legato to feed my opamps. They do the Bal. to SE conversion and have about 8-10dB gain in the present configuration. Input impedance is 4.7K. Actually these are "old version" Borbely discrete opamps with bipolar outputs (I think the last version used MOSFETS).
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Old 7th December 2011, 07:21 AM   #414
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Default Legato 3.1 with dual differential 1704's?

Hi Russ / Brian,

1. Can I use Legato 3.1 for I/V with dual differential 1704 DAC’s (photo attached)? Single 1704 has nominal current-out swing of + and – 1.2mA. Zout of 1Kohm.
2. Will I have enough gain out of Legato 3.1 with such a low current-out level from 1704’s?
3. I am planning on using SE output on Legato 3.1 Do I have to use the outputs from IC2 and IC3 (headphones’) buffers, or can I try the output from pin 1 and pin 7 of IC1? What would be the difference?

Thank you,
Regards,
Boky
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Old 8th December 2011, 11:12 AM   #415
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I had a chance to quickly check the Legato 3.1 specs today.... I see there's "no buffer" option, where the 3.1 uses buffer in the feedback loop……. so that answers my question 3.

I use AD8066 as 1704 I/V - am trying to keep input offset voltage and input current errors as low as possible, followed with transformer for balanced to single ended conversion. Altogether an excellent result…. but one that depends too much on interconnects type / length / pre-amp impedance.

Could someone please tell me if Legato can provide low AND constant offset voltage, and low AND constant bias current to the preceding current-out DAC???

I have searched the threads on Legato and I must say that I am surprised that no one has expressed their concern about Legato [voltage offset + input bias current] errors vs. LSB values of sabre DAC….. maybe people are not interested in low level resolution anymore?

Boky
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Old 8th December 2011, 12:02 PM   #416
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Quote:
Originally Posted by Extreme_Boky View Post
I must say that I am surprised that no one has expressed their concern about Legato [voltage offset + input bias current] errors vs. LSB values of sabre DAC….. maybe people are not interested in low level resolution anymore?

Boky
That is a completely silly thing to say for someone looking for help. I am having a hard time following you. If you claim to understand as much as you seem think you do why exactly are you asking for help?

The ES9018 does not work like other current output DACs, The critical factor is bias modulation at the output. The voltage at the outputs needs to stay as constant as possible. Thus the importance of extremely low input impedance.

To answer your earlier questions. I have no interest in that DAC, so you are on your own. Give it a go. If you do you should be able to simply adjust the gain of the BAL/SE stage. Simple enough if you understand the schematic.

If you don't like the idea of the Legato then do us all a favor and by all means don't try to use it.
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Old 8th December 2011, 01:40 PM   #417
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Originally Posted by leifchristensen View Post
AN 2 watt tants imo
2W because they are carbon film type, for TCR reason I guess. You can use 5W, but they are far more expensive
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Last edited by AndriyOL; 8th December 2011 at 01:43 PM.
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Old 8th December 2011, 02:41 PM   #418
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Originally Posted by AndriyOL View Post
I would say 2W Kiwame carbon film resistors..
These are a horrific waste of money. If you want to use carbon film (and accept the associated higher noise, value drift, etc), just use KOA SPR2 (SPR2CT521R151J KOA Speer Carbon Film Resistors - Through Hole), which are supposedly identical, and much less expensive.

Some say Kiwame resistors are just KOA resistors with a green coating.

If you really don't throwing low noise out the window, you could also opt for metal oxide parts (again, much cheaper).

You will note that not even the Kiwame page lists any meaningful specs (measurements) for the resistors...
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Last edited by BrianDonegan; 8th December 2011 at 02:44 PM.
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Old 8th December 2011, 08:11 PM   #419
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Funny thing that tonight my dac sounds fantastic even with the Vishay Dale. Maybee just because of the 47 uf. Black Gate and 1000 uf Silmic on the output of the supplys and because the caps are burned in !

This is my Final DAC, Final Amp ,Final Transport, Final speakers and Final cables. No more ******* around with Diy all the time.
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Old 8th December 2011, 08:28 PM   #420
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No more ******* around with Diy all the time.
Right, good luck with that. Someone should start a support group for recovering DIY folks.
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