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Old 17th September 2009, 04:32 PM   #2291
iko is offline iko  Canada
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I don't blame you, there's a very intimate relationship between a shunt reg and the circuit it powers. The closer and tighter the ties, the better. Shunt + Load = Love

As long as it doesn't result in flaming love...

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Old 17th September 2009, 10:02 PM   #2292
RCruz is offline RCruz  Switzerland
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Lesson nº xyz
Remenber I had a "woosh" sound on the right channel ?

Well, after thinking about it, I connected the riaa right channel board to the left shunt, and left the right shunt disconnected.

Imediately the woosh disppeared and the sound became stable presenting a credible stereo image.

There is a problem with the right shunt....!

Now I lost a bit of dimension and power but gaining quitness I can now visualize the whole sound picture.

The low PSRR of the riaa benefits more from a low noise feed than sheer power.

The shunt plays a really important part on this design !

Ricardo
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Old 17th September 2009, 10:43 PM   #2293
iko is offline iko  Canada
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It could be that the zener is not properly bypassed. That kind of noise doesn't sound like the usual hum from the power supply. If I were you I'd replace the zener and the cap in that shunt, as a test. It could also be just a bad solder somewhere.
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Old 17th September 2009, 11:18 PM   #2294
Salas is offline Salas  Greece
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First suspects are the Zener and its cap, second set of suspects is the driving BC550 and its 2SK source. Unluckily Ricardo could not get the low noise red glass Zeners online yet. Those with the black plastic and silverish stripe that he has on the photo can be dodgy. Also some assymetry or grounding fault can plague one shunt when using 2 and a remote trafo/rectifier & main filter. Not necessarily by humming on one frequency, but boosting the noise floor well up as a whole. ''Woosh'' is low SNR. First must replace the Zener.
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Old 18th September 2009, 12:43 PM   #2295
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Default my pre is over

some photos

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.
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Luca
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Old 18th September 2009, 01:01 PM   #2296
AndrewT is offline AndrewT  Scotland
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can't see anything of worth using 150 by 113 pixels.
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Old 18th September 2009, 01:13 PM   #2297
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sorry I do not know how to properly post images on forum

http://img36.imageshack.us/img36/9218/spa1318.jpg

http://img29.imageshack.us/img29/1264/spa1317.jpg

http://img156.imageshack.us/img156/5611/spa1315.jpg

http://img33.imageshack.us/img33/1333/spa1319.jpg
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Old 18th September 2009, 03:01 PM   #2298
AndrewT is offline AndrewT  Scotland
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now that is a quality image.

When the Wiki comes back on line, who's going to write instructions for the various ways to attach pics?

And we will not include the way to circumvent the 100k limit adopted by the Forum.
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Old 18th September 2009, 05:11 PM   #2299
Salas is offline Salas  Greece
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Quote:
Originally Posted by urbano63 View Post
some photos
Congratulations!

What exactly did you combine beyond the simplistic in there? Is it OK for hum, and did you have time to listen to it? How do you like it?
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Old 18th September 2009, 08:35 PM   #2300
RCruz is offline RCruz  Switzerland
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The offending zener was replaced and now there is no more "woosh"... both channels sound the same with a very low ripple at full volume...

It seems this component is critical for the "transparency" of the shunt.

With two shunts, I notice a much better transient response and wider soundstage (I believe this is due to the better separation provided by the dual mono setup)

I believe a glass low noise zener with a big Ruby ZLH would make a big difference.

Luca.... Splendid works !

Ricardo

Last edited by RCruz; 18th September 2009 at 09:05 PM.
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