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Old 19th August 2011, 02:38 PM   #351
needsp is offline needsp  United Kingdom
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Hi Russ

Sounds as if it would be worthwhile me changing to 2n2 then- thanks!
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Old 20th August 2011, 07:19 PM   #352
zhai is offline zhai  Denmark
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Hi all

I'm about to build a Buffalo DAC, and I have some questions.

I would like to use the DAC to feed both a power amp and headphones directly, using the Legato, so what would be the best way to accomplish this? Should I just hook the s/e part up to a headphone out, and if I do this, will the signal pass to both headphones and power amp (connected with balanced signal) at the same time?

Should I, instead, find some way of switching between the activation of these two signals, so that I can turn a knob on the front of the DAC?

I guess my level is about intermediate, as I have built only a few pieces of sound equipment before - DDDAC, TPA preamp and UcD power amp.
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Old 20th August 2011, 07:57 PM   #353
avr300 is offline avr300  Denmark
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Quote:
Originally Posted by zhai View Post
Should I just hook the s/e part up to a headphone out, and if I do this, will the signal pass to both headphones and power amp (connected with balanced signal) at the same time?
That's the way I do it and it works flawlessly.
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Old 20th August 2011, 09:43 PM   #354
LeonvB is offline LeonvB  Netherlands
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Quote:
Should I just hook the s/e part up to a headphone out, and if I do this, will the signal pass to both headphones and power amp (connected with balanced signal) at the same time?
Correct. The SE out of the Legato should be powerful enough to drive most headphones.
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Old 20th August 2011, 09:55 PM   #355
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Anyone know how low impedance its possible to run on the balanced output ?
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Old 26th August 2011, 02:58 PM   #356
MWL168 is offline MWL168  United States
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Default increase SE buffer output

Hi Russ:

I can not get enough volume with my Audaze LCD 2 headphone which is rather inefficient. What can I do to increase the gain of IC1?

Thanks!
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Old 3rd September 2011, 03:05 AM   #357
MWL168 is offline MWL168  United States
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Default Legato 3.1 SE output gain

Hi Russ:

Based on what was stated in the Ventus headphone amp manual; I assume the gain of IC1 is R21/R17 = R22/R18 = R23/R19 = R24/R20. Is this correct?

I also have the following questions:

1. Is it better to lower the value of the resistors determining the input impedance to IC1 (R17 - R20) or raise the value of the feedback resistors (R21 - R24)?

2. If I choose to lower the value of R17 - R20, is it necessary to make the R33 - R36 the same value?

3. Do you have recommendation what resistance range I should use? Currently, using iTune on my Mac BookPro laptop as source, I have to be in the last 1/4 of adjustable range of the Volumite to get enough volume - this with the iTune's volume maxed out.

Thanks!
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Old 3rd September 2011, 03:46 AM   #358
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For best results simply adjust R21-24. Try doubling them for now.
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Old 3rd September 2011, 10:08 PM   #359
MWL168 is offline MWL168  United States
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Thanks Russ!

I don't have 10K resistors handy so instead I put 7.5K Caddock MK132 0.1% in R21 - R24. I still have to turn the Volumite pass 2/3 of the way but I am now getting enough volume for my headphones.

Unless you have concerns I'll just leave the Legato the way it is now.

Thanks again for your help!
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Old 8th October 2011, 09:48 AM   #360
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Default Legato 3 with discret opamp

Anybody know if it is possible to change the LME 49720 to a Dexa discret opamp ( the Dexa have Bipolar input cicuit ) ? I am asking because of the common feedback circuit.
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