Wilson Audio MAXX resistors


I am about to replace resistors on my MAXX-1 which is in use for the last 10 years. There is no information in the instruction manual and i have absolutely no idea which resistors are to be used for mid/hi freq.. Does anybody have any information on the effect and procedure for resistor replacement/selection.
fpooyandeh

Showing 12 responses by pbnaudio

Why do you want to replace them ? They don't wear

I'd recommend these if you just want to try different values

Caddock MP9100

Best of luck

Peter
Polk,

If they do, they are seriously wrongly implemented in the crossover as far as power handling goes. In a properly designed crossover network the resistors should not heat up causing their value to change.

Good Listening

Peter
Kkurtis,

I have no argument with that Wilson is a class act, their presentations etc at shows are very impressive, the whole organization comes across very professional. Like wise they build a product with extreme fit / finish.

This of course leads to the question, why implement a part as simple as a resistor that is so under valued as far as power handling that it "wears" out, when there surely are many many choices of resistors that would be powerful enough for the application. Also what does this resistor do to prolonged sound quality does it gradually decline as the resistor "wear" or does it just open up when its service life is expired causing the driver to quit.

From a top quality outfit like Wilson this seems like a sub par engineering choice

Good Listening

Peter
Polk,

In your argument the difference is that a tube do have a finite lifespan, its design dictates that. A resistor properly implemented have a unlimited lifespan it will not wear out, my first post on this subject. To reverse your argument would you expect to replace the output transistors on your SS power amplifier?, probably not.

Good Listening

Peter
Just because it is intentional it does not make it sound engineering. Yes there certainly is different approaches, I would never use a resistor as a fuse, and I'm sure David Wilson does not give a hoot about that too :-).

Good Listening

Peter
Polk, no not really.

A resistor used as a fuse, in my mind is just not the right approach. If it is supposed to act like a fuse, and have any effect to that cause it will have to be run so close to its power handling capability that it heats up so much that it almost self destructs. Doing that time and time over will cause it to change in value which will result in a SPL level change form the driver it is attached in front of. There are many other ways to protect a driver in the crossover design.

Think of to this way, you as the end most likely use speaker wires that have been terminated with super fancy connectors, have AWG the size of welding cable. In addition you have painstakingly tightened your connections with a torque wrench etc, all because you want good tight connections with almost no termination resistance. (probably exaggerated but it helps prove the point)

As the manufacturer of the Speaker you go to great length installing binding posts with almost zero termination resistance, using wire of many times greater AWG that actually required or fancy alloys etc, using capacitors of extreme quality, inductors of Oxygen free copper, etc. and then you finish it off with a component that is run so close to its limit that is is on the verge of breaking all the time and will if you run it just a little over limit. To me that does just not make any sense.

Good Listening

Peter

Bj,

Did you read the entire thread? , I'd recommend starting with the first
post, please do, and then let us know your position on this subject.

And who is the Elk anyway ?

Good Listening

Peter

Bj,

Accepted and thanks for "manning up" the net is full of "Keyboard Ninjas" that post utter nonsense and insults, hiding behind a moniker with no consequences.

I don't know why the Wilson team has chosen this approach, which to me and to others here seems questionable, only they can answer that question.

One thought can come to mind, they simply do not want a driver failure. Because of a marketing position they view that a blown resistor is more palatable to their target group than that of a driver failure, even if this solution comes with some sonic degradation happening over time. Before you and Polk get all puffy again, there is no way this does not happen because of the "resistor fuse" heating up over and over again, and eventually failing. If a resistor is used as a fuse it will have to be run too close to its maximum power handling capabilities even when playing moderately loud to have any effect to that cause.

In your example you were cranking it up while zipping wine and the speaker gave up, had the resistor had adequate power handling you would have rocked on and that would have been the end of it. I would not worry about damaging drivers, if they are behind a properly designed crossover they are pretty sturdy.

A high end system from my point of view certainly should be able to be played loud and proud at times without the risk of it shutting down. That being said gross abuse, amplifier oscillation etc, can and will cause driver failure even with the best designed crossovers.

When you are buying a Wilson speaker you are buying more than just a loudspeaker you are buying a status symbol. They more than anyone have been very successful at conveying that message to their potential group of customers. They come in very fancy cabinets, have leather bound manuals etc. All which of course have nothing to do with that actual purpose of the product, which is to make sound, but it certainly enhances the perception of the speaker.

That of course also the reason that you and Polk react the way you did "how dare someone tell me that my loudspeakers are not perfect ! I was told they were"

Good Listening

Peter
I think I found a way to explain this that is quite easy to understand for everyone:

It is like putting a 80 MPH governor on a Ferrari!

Good Listening

Peter
Hifi,

I agree with the attitude, the ones that feel personally offended if one dares to question a design choice made by the maker of their speaker seem to have it in spades :-)

Anyway, I must clearly question your statement replacing said resistors due to "lightning strikes" are you serious ???  In the rest of the system that the speakers presumably were hooked up to at the time of the "Lightening Strike" there are components way way way more fragile than the above mentioned resistors, did you replace them too ??  Once a lightening strikes anything it usually disintegrates.  That would go for the Amplifiers Preamps etc which are connected to the electrical grid directly - your speakers are not  - they are only connected to the amplifier thats connected to the grid and it would be TOAST.  

So you'll have to come up with a better explanation to why the resistors needed replacing - if you read comments above you may find an answer.

And for the record, I never questioned the value/sound/looks of Wilson Speakers - In fact I think he has done a fantastic job with his company - what I do question is the use of resistors as fuses - electrically it makes  zero  sense.

Good Listening

Peter   


  
Mr_M

Yes they certainly do - however all resistors have a Wattage rating as well which is how much power they can safely handle without heating up and self destruct - a properly integrated resistor should have adequate power handling capabilities to not change its properties when in use.  

Proper practice is at least twice the wattage rating of what the resistor will see in actual use.

In a speaker crossover this is doubly important, depending on where the resistor is inserted in the circuit it will change the frequency response of the speaker system, if inserted anywhere after the first component in a specific crossover rung, its change in value will change both SPL and crossover frequency, this because all preceding components in this rung values are selected based upon seeing a constant load.   In some cases one can place the resistor as the first component but then its even more important that its of proper power handling capabilities as it must be able to dissipate all the effect consumed by the shunt components in the crossover also,  however in this case only a SPL change will happen.

For examples of crossover implementation here are a few examples

http://pbnaudio.com/speakers/speaker-kits/scanspeak-b741
 
http://pbnaudio.com/speakers/speaker-kits/xmax

Good Listening


Peter