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6C33 OTL Fine tuning - BGs, ground and wire dressing

Posted 3rd March 2013 at 03:58 PM by wlowes
Updated 8th December 2014 at 01:39 AM by wlowes (Update - Bulk foil resistors)

The amps continued to run in and proved to be keepers. Well worth doing some final spit and polish. There was a little hum on one amp and some noise / hash on the tweeters of both channels. Nothing major, but certainly audible at 1 foot.
Using AC filament supply for all but the input tube, I figured I should re read the best practices on wire dressing, hum pots, virtual center tap etc.
Looking back there were some spots to improve.
1. tight wire twist on path from bridge rectifier to first caps. Done, no real change.
2. tight twist on b+ supply to input tube plus added BG 3uF 250v cap right at the tube. No change to noise but love the improvement in sound
3. tight wire twist from psu to b+ on all power tubes plus BG 10uF 250v on each power tube. Like the input tube the BG brought an immediate lowering of noise floor that really brought a finishing to the SQ. Quiet background, micro details and just a smooth rich sound. Not colored, just the way it...
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Old

The best sounding I/V resistor

Posted 3rd March 2013 at 10:22 AM by dvb projekt
Updated 3rd March 2013 at 04:17 PM by dvb projekt

As many of you know, i am using the Texas Components TX2575 Bulk Z-Foil resistor for a long time
in important circuit positions, especially as I/V resistor.

Recently i stumbled over a short recommendation from Thorsten Loesch.


Quote:
Originally Posted by ThorstenL View Post
Hi,
I would second Rohpoint, Neohm less. Rohpoint are truely excellent. For my first TDA1541 Non-OS DAC (in 98) I handmade bifilar wound Non-inductive 25 Ohm resistors.
In susequent builds I compared to Rohpoint (which I have used extensively and found no reason to handwind resistors.

In my commercial designs we use a specfic type of SMD resistors after auditioning tons.
Some SMD resistors are really bad, some are so-so and some are most excellent, though no patch for a Rohpoint Squaristor GR102.

Ciao T

Because i know Thorsten as a man who had the perfect sound in mind,
i ordered one pair 30R to try them in my Tube-I-zator.


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