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Old 29th March 2012, 11:01 PM   #121
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Pemo:

Those values are in a post in this thread by AndrewT...

I used 10 Ohm resistors, 0.001uF capacitors and 1.5uH inductors. AndrewT recommended a range value in each component, I picked up all the highest ones.
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Old 29th March 2012, 11:08 PM   #122
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Thank you again, Pacificblue and DigitalJunkie.

At the end, when I have everything ready, all the grounds will join the earth/safety ground, including this purple "shield" wire, correct?.

I also need to know how to solder the inductor and resistor in parallel in the + speaker output cable, what AndrewT calls the Thiele Network.

Do I have to do it like this:

inductor
--------wire------ ---------wire---- (wire cut, resistor/inductor in the middle)
resistor

Or can I do it like this:

inductor
------wire-------------------------------------wire------- (no wire cut)
resistor

Thanks again.

Last edited by Aguilabrava; 29th March 2012 at 11:10 PM.
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Old 29th March 2012, 11:20 PM   #123
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Default Zobel + Thiele

Pemo:

If you want to see the Zobel and Thiele networks in the schematics, go to National's LM3886 Data Sheet:

http://www.ti.com/lit/ds/symlink/lm3886.pdf

Look for page #6 in the PDF document (Page 5 in the printed version), you will see them in the diagram for Test Circuit #2, the top section Cf and Rf2 is the Zobel, the L and R in parallel at the bottom-right is the Thiele.

They are also shown on the "Single Supply Application Circuit" diagram in page 7.
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Old 29th March 2012, 11:25 PM   #124
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(I don't understand this 2r0)
Thanks and RGDS
Pemo[/QUOTE]

I didn't realize you had the quote including all values recommended by AndrewT, anyhow, 2r0 means 2.0 Ohms.
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Old 29th March 2012, 11:26 PM   #125
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Pacificblue, please check posts 112 and 122...
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Old 30th March 2012, 01:37 AM   #126
Pemo is offline Pemo  Mexico
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Hi Aguilabrava (like your name),
Thanks for the information. I'll build another amp with all this "improvements" to the kit and compare both, the one i built before and the XY Plus (nice name eh?).

Here are some pics of my first XY 3886.
028.JPG

032.JPG

033.JPG

I might use this new chassis for the XY Plus
P1080080.JPG

RGDS

Pemo
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Old 30th March 2012, 09:29 AM   #127
AndrewT is offline AndrewT  Scotland
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Quote:
Originally Posted by DigitalJunkie View Post
Connect it to the safety/earth ground.
Quote:
Originally Posted by pacificblue View Post
The shield connects to ground.
that shield connects to chassis. The wire should be short to minimise inductance. This requires that the shield be chassis connected right next to the transformer. Not at Safety Earth, not at Audio Ground.
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Old 30th March 2012, 09:32 AM   #128
AndrewT is offline AndrewT  Scotland
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Pemo,
you have confused the Speaker Zobel with the Amplifier Zobel.

The Speaker Zobel is there to smooth out the driver impedance so that the passive crossover can do it's job more accurately.

The Amplifier Zobel is there to give the amplifier a load at very high frequency and thus improve stability.

These two Zobels are at opposite ends of the system.
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Old 30th March 2012, 09:36 AM   #129
AndrewT is offline AndrewT  Scotland
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Aqui,
the R//L goes into the speaker feed wire between the amplifier output (PCB) and the speaker terminal (chassis).

Try to keep the inductor away from the amplifier PCB and not too close to a steel chassis/component.
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Old 30th March 2012, 02:36 PM   #130
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Default R//L Thiele.

Quote:
Originally Posted by AndrewT View Post
Aqui,
the R//L goes into the speaker feed wire between the amplifier output (PCB) and the speaker terminal (chassis).

Try to keep the inductor away from the amplifier PCB and not too close to a steel chassis/component.

AndrewT:

Then I can solder the resistor and inductor together in parallel, attach one end to the + speaker output terminal and the other end to the wire coming from the PCB?

I was thinking about removing two little pieces of insulation from the wire coming from the PCB, like 2mm each, and then solder the inductor on top side and the resistor on the bottom side, then putting some heatshrink to cover both resistor//inductor. My question is, would this work since I am not cutting the wire, just two 2mm sections of its insulation to solder the components, or the wire has to be cut and then joined together by the resistor//inductor?.

I am attaching a picture...
Attached Images
File Type: gif Thiele.gif (10.2 KB, 438 views)
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