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Old 17th October 2011, 05:31 PM   #371
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Wow! This makes me very happy indeed.
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Old 17th October 2011, 05:58 PM   #372
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Quote:
Originally Posted by oneoclock View Post
1000 Hz. + 7 dBu. measure 7 dB down is correct.
The measures in balanced and unbalanced are very close.
The output level and measurement equipment configuration is identical to IVY

Click the image to open in full size.
Legato III 3.1
What does that work out to in terms of THD? I am very pleased with the picture so far.

I am suspicious that there may something wrong with your IVY-III or possibly there are some resistor values that should be tweaked. Because the performance is very far off the mark.

Is there anything different about it from stock? Is it mounted using the mezzanine connectors?

Thanks!
RUss
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Old 17th October 2011, 06:08 PM   #373
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Get this distortion has cost me effort. The transistors Q2-Q3 and Q5-Q6 have to go well together and touching. I've been moving this until they were good together and lowered distortion. I had -115 (-122) dBu two harmonics one positión but I could not place again.

They should be glued in origin before soldering?

This measure is a Textronix AM700, is worse than a Audioprecisión and may be in poor condition. But compared to other DAC is the best I've ever measured.

Will I try to measure a Buffalo IVY from a friend to see if they look to close Ivy measures than mine. Do not go to be defective.
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Old 17th October 2011, 06:15 PM   #374
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Yes I placed the patterns back to back specifically so that the Qs could be joined thermally. I am glad you picked on that. I will make it more explicit in the manual. I glue mine together with a little thick CA or epoxy.

Great work!

So it seems to me that works out to something between -116 to -118db THD?

Very good. Thanks for sharing!
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Old 17th October 2011, 06:17 PM   #375
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Well I have been considering a resistor value change in IVY-III. Your testing may help me decide new values along those lines. I really appreciate you sharing your results.
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Old 17th October 2011, 06:26 PM   #376
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Everything is mounted like regular unity.
The balanced and unbalanced IVY measures had a similar measure.
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Old 17th October 2011, 06:27 PM   #377
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Quote:
Originally Posted by Russ White View Post
Yes I placed the patterns back to back specifically so that the Qs could be joined thermally. I am glad you picked on that. I will make it more explicit in the manual. I glue mine together with a little thick CA or epoxy.

Great work!

So it seems to me that works out to something between -116 to -118db THD?

Very good. Thanks for sharing!
What ? New information to and "old" board. Manual says zip

Lid off again - mixing epoxy...
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Old 17th October 2011, 06:30 PM   #378
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OneOClock are those stock resistors?

Are you using 12 or 15V rails?
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Last edited by Russ White; 17th October 2011 at 06:33 PM.
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Old 17th October 2011, 06:31 PM   #379
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Quote:
Originally Posted by avr300 View Post
What ? New information to and "old" board. Manual says zip

Lid off again - mixing epoxy...
Sorry for the omission. I will correct that.
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Old 17th October 2011, 06:37 PM   #380
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Quote:
Originally Posted by Russ White View Post
Yes I placed the patterns back to back specifically so that the Qs could be joined thermally. I am glad you picked on that. I will make it more explicit in the manual. I glue mine together with a little thick CA or epoxy.

Great work!

So it seems to me that works out to something between -116 to -118db THD?

Very good. Thanks for sharing!

When the two transistor was very closed together, the values oscillates between -115dB to -120dB (15 seconds of period)

Correctly glued will drops to -122 dBu (or less)

I remark, all the values needs to be corrected with 7dB less, -115dBu = -122dBu
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