Wilson Audio Maintenance

marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
Sorry, I have been unable to use my computer at home which had to replace, and work has me buried recently. I had said I would give the values of the resistors I bought which were 5R9-10wt and a 6R5-10wt. Later today I will post reply to questions asked after I have time to read and answer.
 

microstrip

VIP/Donor
May 30, 2010
20,806
4,698
2,790
Portugal
There is at less one good reason for the different sound characteristics of Duelund resistors. Although we do not have the details we know they are "cast graphite" . Graphite has a negative temperature coefficient - this means that the value of the resistance will decrease with temperature. Caddock resistors have a minimal positive temperature coefficient, of much smaller magnitude.

This article on this subject is worth reading: http://www.troelsgravesen.dk/graphite.htm

b1.jpg
 
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rhyno

Well-Known Member
Dec 29, 2010
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good for folks to know, but always remember the more resistors you put in parallel, the lower the temperature impact would be, thus negating the negative temp coefficient. so, instead of 1* 5r, try 2* 10r, or 4* 20r ----same r, but power handling 2x in each instance
 

marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
There is at less one good reason for the different sound characteristics of Duelund resistors. Although we do not have the details we know they are "cast graphite" . Graphite has a negative temperature coefficient - this means that the value of the resistance will decrease with temperature. Caddock resistors have a minimal positive temperature coefficient, of much smaller magnitude.

This article on this subject is worth reading: http://www.troelsgravesen.dk/graphite.htm

View attachment 48065
I realize I did a poor job of explaining what differences I heard by replacing the resistors. When mentioning tweeters sounded sweeter they did, but what I should have said was the transients were clearer so everything was expressed more clearly. The jump factor increased and voices easier to follow. It sounds to me that the Duelunds are faster so the starting and stopping of notes from voices and instruments are easier to understand. I love my stereo but I am always open for ways to noticeable improve sound. I would not let these technical arguments keep me from testing anything for sound improvement as long as the cost is reasonable. When reading what Debby said it prompted me to share my experience since this site's name implies the people here are interested in getting the best sound they can.
 

marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
good for folks to know, but always remember the more resistors you put in parallel, the lower the temperature impact would be, thus negating the negative temp coefficient. so, instead of 1* 5r, try 2* 10r, or 4* 20r ----same r, but power handling 2x in each instance
Not sure if your statement about, more resistors you put in parallel, is related to a previous post or not, as I am replacing resistors, not adding
 

marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
The Caddocks take a while to break in. Impossible to seriously compare old resistors to new.
Seems like most thing in sound reproduction need some break-in to me, so after extended break-in is when I compare changes.
 

C.A.P

Well-Known Member
Apr 23, 2010
139
17
363
I am always up for a tweak . That being said, Sophia 1 is not the easiest to get to without a lay down and disassemble of the bottom..

Did you do just tweeter and midrange or Woofer to ?
 

C.A.P

Well-Known Member
Apr 23, 2010
139
17
363
Not sure if your statement about, more resistors you put in parallel, is related to a previous post or not, as I am replacing resistors, not adding
Paralleling resistors with double the value raises wattage but halves their value! IE..... ..2x 10Rx10 --------< ======>------ will be a 20 watt 5r ..
 
Last edited:

rhyno

Well-Known Member
Dec 29, 2010
65
24
913
thats exactly what i wrote CAP.: 2* 10r or 4* 20r = 1* 5r but the former have considerably greater power handling and (with duelund) less variance due to heat per the lower power handling per r when they're paralleled.
 

marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
I am always up for a tweak . That being said, Sophia 1 is not the easiest to get to without a lay down and disassemble of the bottom..

Did you do just tweeter and midrange or Woofer to ?
The tweeter and midrange. I am not sure if there is one on the Sophia III as I see no compartment for them.
 

C.A.P

Well-Known Member
Apr 23, 2010
139
17
363
underneath is a panel that has the 20 ohm woofer and .05 phase resistor ! What a phase one does is odd to me as it must slow down something ! I have pics
 
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marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
I am at work now so when I go home I will check, but I do not remember anything on the bottom when I placed Stillpoint ultras underneath and then replaced with ultra 5s later. I have the III version, is that what you are referring to?
 

C.A.P

Well-Known Member
Apr 23, 2010
139
17
363
Yes the 3 have a 20 ohm bass Wire wound Caddock and a Flat .05 caddock for phase ..If I recall the whole bottom has to come off !
 
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marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
Yes the 3 have a 20 ohm bass Wire wound Caddock and a Flat .05 caddock for phase ..If I recall the whole bottom has to come off !
My manual says the resistors were moved from bottom to the back of speaker for the III version. No mention of a bass resistor. Are you going from memory?
 

analogsa

Well-Known Member
Apr 15, 2017
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Btw, replacement resistors of similar wattage to the Caddocks, but with a different formfactor will fail to efectively act as fuses. The reason being the Caddocks, despite their high dissipation figures can only manage about 5W without a heatsink.
 

marcbrown

Well-Known Member
Apr 17, 2018
51
4
90
My manual says the resistors were moved from bottom to the back of speaker for the III version. No mention of a bass resistor. Are you going from memory?
Btw, replacement resistors of similar wattage to the Caddocks, but with a different formfactor will fail to efectively act as fuses. The reason being the Caddocks, despite their high dissipation figures can only manage about 5W without a heatsink.
Before I switched to Devialet from a 400 wt Audio Research amp I blew 3 tweeters, 2 at same time one party and the tweeters fried but the Caddock resistors were fine. Wilson made me pay even though under warranty, said I abused them. Not sure if the Duelund CASTs would have protected in that case, but the Duelunds protected tweeters driven by Devialet repeatedly loud as they blew first. So from my experience Duelunds worked better at protecting tweeters
 

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