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Old 30th July 2011, 07:22 PM   #6671
RCruz is offline RCruz  Switzerland
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Replaced the FT-1 by same value REL-CAP and now there is no difference between channels.

Both have the same gain and the same very low hiss.

The Ft-1 on the left channel was the responsible by the errors.

Anyway, I learned a lot during the process.
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Old 30th July 2011, 07:41 PM   #6672
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Old 30th July 2011, 07:54 PM   #6673
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I'm, glad to hear you fixed the issue.
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Old 30th July 2011, 11:40 PM   #6674
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Quote:
Originally Posted by Salas View Post
All your questions are covered in the pdf guide linked from post#1. Read it.
Salas είσαι κορυφή.

Θα το φτιάξω με την πρώτη ευκαιρία.

thank you :-)
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Old 4th August 2011, 12:12 PM   #6675
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43dB DL160 Salas Riaa update.

After debugging the difference in gain between channels, I compared this build with the one I made for my Benz ACE M and found it to roll a bit in the lows so I did the following actions:

Remove the RC filter in second stage (gone with the 100r + 680uF)
Now there is no filter in 1st and second stage... (I left a 680uF on the buffer drain just to be sure there is enough juice for transients there)

Add a 1k2r on between the psu Vin and the CCS jfet in first stage. (It was direct)

Remove the trimmer on second stage Rsource and replace it by a 46.5r.

Sound became much faster with outstanding attack and the lows are much cleaner and detailed.

I guess the major benefits come from removing the 680u + 100r RC on second stage, but the fixed resistor in second stage Rs also brings more definition.

Lowering current in the CCS adds some ease to it all.

The Rel Cap polystyrene & Tin Foil in the 15,33nF riaa filter position is much more (alive) than the FT-1, althou it lacks the ultimate extension and sweetness in the highs.

Outstanding results.

Thank you all for the precious help.
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Old 4th August 2011, 02:16 PM   #6676
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Its lowering dissipation on the leds ccs jfet by dropping voltage on that 1k2 you used, not ccs current btw.
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Old 4th August 2011, 02:32 PM   #6677
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Quote:
Originally Posted by Salas View Post
Its lowering dissipation on the leds ccs jfet by dropping voltage on that 1k2 you used, not ccs current btw.
Thank you for the correction.... As the jfet acts as a CCS, the current remains the same of course... Sorry for the mistake.
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Old 7th August 2011, 06:34 PM   #6678
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Default GND setup

During this weekend I converted the V12 shunts on my initial Benz Riaa build to V12R.

In the end, I noticed hum in the right channel and decided to implement a new GND setup.

I followed this schematic that totally eliminated hum.
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File Type: jpg cruzgnd B&W.jpg (90.0 KB, 157 views)
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Old 7th August 2011, 06:39 PM   #6679
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Here is the Benz Riaa original schematic.... Next move will be to remove second stage RC filter (C5 R5)
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Old 7th August 2011, 06:44 PM   #6680
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That GND sketch reminds me something? By the way, 1.2 or 1.2R must be checked with oscilloscope over the rails to be sure there are no oscillations in the few MHz range, those are ''fast'' circuits. Little reg layout changes from build to build can make them sing.
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