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Old 3rd November 2006, 03:42 PM   #4481
SimontY is offline SimontY  United Kingdom
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With this article fresh in mind does anyone have any opinions on the usefulness of making the ground line on the regulator boards extra thick? I assume the lower the resistance the less the problem. I could add a copper wire along all of it and solder it all up with lots of solder, reducing the "parasitic resistance" of the ground paths to something very low. That should reduce the noise.
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Old 3rd November 2006, 03:44 PM   #4482
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Quote:
Originally posted by poynton
Yes. the mag is old ond a bit faded hence the poor copy quality.

Andy
Ahha, thanks for doing it. Page 3 was hard to read but doable! For future reference I would recommend scanning at 300dpi, in mono, then inserting each page into a DTP program like Publisher, then converting it into PDF format. This will make a small file with very good readibility when printed.

Simon
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Old 3rd November 2006, 03:46 PM   #4483
AndrewT is offline AndrewT  Scotland
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Hi Poynton,
that article confirms the transformer centre tap to audio ground and smoothing caps 0v wired to audio ground. Nice to hear that someone else has seen the light 14 years before me!

Note, that the audio ground is NOT mounted on the joint between the smoothing caps of the dual polarity supply. This is really important.
Quote:
scanning at 300dpi, in mono, then inserting each page into a DTP program like Publisher, then converting it into PDF format. This will make a small file with very good readibility
am I supposed to remember this?
How about starting a Wiki describing the process in detail?
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Old 3rd November 2006, 03:58 PM   #4484
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HI.

The following is an extract from the LM317 spec sheet.

Quote:
Load Regulation
The LM317 is capable of providing extremely good load
regulation, but a few precautions are needed to obtain
maximum performance. For best performance, the
programming resistor (R1) should be connected as close to
the regulator as possible to minimize line drops which
effectively appear in series with the reference, thereby
degrading regulation. The ground end of R2 can be returned
near the load ground to provide remote ground sensing and
improve load regulation.



The last line backs up the article.

Andy
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Old 3rd November 2006, 04:01 PM   #4485
AndrewT is offline AndrewT  Scotland
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Hi Simon,
had another look at post4464.
The smoothing caps BEFORE each regulator break grounding rule 2. They need a separate return to ground NOT a shared return with the post reg returns.
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Old 3rd November 2006, 04:03 PM   #4486
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by AndrewT
Note, that the audio ground is NOT mounted on the joint between the smoothing caps of the dual polarity supply. This is really important.
OT, but I'd like to know more about this. In my power amp I have the centre point between the smoothing caps (split supply) as the star. Am I wrong to do this then??

Quote:

am I supposed to remember this?
How about starting a Wiki describing the process in detail?
lol. Don't know how to do that. I'll look into it later if it seems useful to people.

Simon (off for a workout then soldering BGs or grounds then beers)
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Old 3rd November 2006, 04:18 PM   #4487
poynton is offline poynton  United Kingdom
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Quote:
Originally posted by SimontY
With this article fresh in mind does anyone have any opinions on the usefulness of making the ground line on the regulator boards extra thick? I assume the lower the resistance the less the problem. I could add a copper wire along all of it and solder it all up with lots of solder, reducing the "parasitic resistance" of the ground paths to something very low. That should reduce the noise.

Hi.

I think the lesson is that the regulator should be as close to the load as possible with the return to a star earth.

Andy
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Old 3rd November 2006, 04:22 PM   #4488
SimontY is offline SimontY  United Kingdom
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Quote:
Originally posted by poynton
Hi.

I think the lesson is that the regulator should be as close to the load as possible with the return to a star earth.

Andy
Sure seems that way! I'm getting a little bit tired and confused now but let me know if this is closer to ideal (ignore bottom reg board).

Simon
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Old 3rd November 2006, 05:57 PM   #4489
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Hi Simon,
post 4589,
the caps before the regs and the reg 0v should each have their own grounding connections. That applies to ALL the regs including the 3 at the bottom.

It's all down to seeing that the rectifier and following smoothing caps are part of the charging circuit and that they need their own return loops to keep the buzzing out of the clean stages.

It helps if the smoothing caps and the rectifiers are kept in close proximity and with a very low loop area in the flow and return wires.
Similarly the transformer to rectifier cabling should also have a small loop area for the flow and return wires.

Is the cdp in it's own metal case? If so then the "E" should have a permanent connection to chassis. Again the RCAs should be isolated from chassis.

I see a note beside the 6r8. If you really want to experiment then add a switch in parallel to the disconnecting networks. This is often called an earth lift switch in commercial gear. I do not recommend you leave the switch closed. But feel free to experiment with it. Leaving two earth lift switches closed (whether in sources or pre-amp or power-amp) will create a hum loop and you will hear it. TRY IT and tell us.
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Old 3rd November 2006, 06:19 PM   #4490
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Guys,
I've opened a new threat (sorry Simon I've quoted you and they do not agree...)
Arcam Alpha One upgrade


I've enjoyed some discs, and now I'm almost sure that it sounds not better or worst, but diffrent:
On this heavy rock, White Zombie "Astro Creep 2000" used to sound as Nuclear Assault's records: because of mess and boomy bass it felt powerfull and dense. Now White Zombie sounds more clear, and some feeling of power has gone, even if all the instruments has appeared more clearly. I just need to be used too, but the pleasure is really there!
Click the image to open in full size.

I'm also using some left parts (Farnell has some minimum quantity when order a part) to upgrade the PS of my Sansui tuner, and then what's left will be sold as a pack on eBay. Many things like Elna RJH, Rubycon ZLH...
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QED T260, Thorens TD-318, Marantz CD-43, TK2050, JBL 4313B & MJK's OB: music!
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