Crossover shunt upgrade. What obstacles to look for? Worth upgrading?

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gringo117

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Hello to every tinkerer, DYI enthusiast, curios people of how things work and make them better.

This is my first post or question on any audio site, so bare with me and my ignorance in regards of knowledge about audio.

I am in the middle of upgrading my speakers: Triangle Borea BR03. Not that they sound bad, quite the opposite, but I believe that they can do better.
I am doing it in stages and not in a real hurry. First I ordered some material to dampen the  resonance of the box. I have already cleaned the box of the old material and the glue. Some antivibration paint will be used, then felt will be glued on the walls and last the dampening polyester will be put back.
That part is pretty straight forward.

Also understanding the circuitry of the crossover and drawing down its elements for the low pass filter and high pass filter was fine. Well, not understanding, as the values of each part and why used is definitely out of the reach of my knowledge of electronics in regards to the drivers.

I went through several feeds/post, videos and could not find the answer that would satisfy me about the crossover shunt upgrades. The reason why I am asking is that I want to change all the parts in the crossover and in the high pass filter there is a shunt with and air coil inductor. I can meassure the inductance of that coil and replace it if the thicker gauge air coil (same inductance), as the origin one has very thin gauge wire.

And here come my doubts. If I change that, then the resistance decreases quite dramatically in the shunt. Would there be a need to add a resistor in serial after the coil to have the same value as in the origin set up? What is the purpose of this upgrade then? Lower "noise" of the resistance of the new coil + resistor ?
What other obstacles to look for?


richidoo

Hello Gringo, welcome to AudioCircle!

Any changes made to a well designed commercial speaker will change the sound of it. The stuffing, the cabinet resonance, the DCR of conductors is all considered and accepted by the design team after 100s of hours of listening tests. Of course, they build to a price, and some compromises are made with quality of materials and build process. But these compromises are compensated with engineering choices and voicing tweaks. So upgrading small coil for larger gage coil may bring some improvement in one way, but reveal faults in another unexpected way. But your taste in SQ will be different than the Triangle engineers, and there's nothing wrong with tweaking a speaker to suit your own taste and learning about speaker design in the process. Most people trade speakers based on tweeter voicing, so learning to adjust the tweeter resistors can fine tune a speaker to your taste and avoid the churn.

Likely you will not hear much difference by increasing the tweeter coil wire gage, but it's noticeable if the change in gage is big.  I think I have 14ga on my tweeter. That's bigger than most woofers, and comparing it to the 22ga stock there is a noticeable difference, but can't say better, just different. Audiophile perspective would say it's more detailed, but "music lover perspective"  would say the added detail can be distracting or even annoying on lesser recordings. I never tried a compensation resistor on it, but I did install a 100ohm resistor in parallel with shunt tweeter coil to damp coil resonance, I liked that. Rick Craig of Selah Audio advised to add a compensation resistor in series with the bigger shunt coil, but I have yet to try that 5 years later...  he is usually correct about such things. :)
 
The woofer coil gage is far more critical because it is in series and the resistance is inversely proportional to the electrical damping of the woofer cone, so less resistance = better damping = more midrange detail and bass "slam."

Upgrading the tweeter cap(s) may yield more valuable improvements because stock caps are almost always barely "adequate."  I like to use Jantzen caps, I think they are great value for the money. Even the red SuperiorZ is vastly better than Solen or bennic typically found in stock XO circuits. But not as costly as Mundolf, Clarity, Jupiter, teflon etc. Upgrading woofer cap will have less affect than on tweeter.

The shunt resistance of the tweeter coil does affect the attenuation of the tweeter. Reducing coil DCR will make the tweeter sound louder, but because the shunt coil is probably followed by resistor network dedicated to attenuation, the effect of the small change in coil DCR may not be noticeable. You can try the new coil with and without a physical DCR compensation resistor to see if it matters. Speaker voicing is an art, there are very few "absolute right" answers.

Be sure to lift one leg of the stock tweeter coil off the XO circuit so you can get accurate measurement of its DCR to compare to the replacement coil. Resistor noise is not a concern with speaker level XO filters.

Other obstacles to look for: psychology of critiquing ones own work is tricky business. Adjust the sound to suit the immediate impression, but then after you think it is good enough, then allow lots of listening time on lots of different music before you make final acceptance. What sounds good on initial change, may grow tiresome after an hour or a month. Or, one particular song may reveal a problem not heard when you made the change. The tweaks will get lesser and lesser as you approach the ideal. If you decide "it's done" and then have to tear it open again a week later, over and over, then it will discourage you. Understand from the beginning that voicing is not like adjusting a carburetor or fixing spreadsheet. You are fitting a tool to best interface with your mind, and the mind is fickle so be patient and always see the humor in your self-deceptions. Remember this is supposed to be fun, even when it isn't. Don't expect it to be easy. Easy is just leaving it alone, "good enough." Like any worthwhile endeavor, the last 1% is the hardest to achieve.

Phil A

Welcome to AC!

gringo117

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Thank you Phil and
Thank you Richido for the reply.

You really got me with the last part about the other obstacles.   Those a years of experience speaking. Patience and persistance.
It is rarely that something goes right after the first attempt. In almost anything. Not trying to achieve that, however I am not against it, if it happens.   :)

Never the less "measure twice, cut once" is the method here for me and if the result is not good, then the process starts again.
I was not yet at that stage and was not considering, how to troubleshoot the speaker/crossover. So that is something that I will need to think about when putting the XO back: should be easy to put in and take out. Thanks for that.

Yes, the caps are already chosen: funny as Jantzen SuperiorZ are the replacements. Resistors Mundorf MResist Supreme.
On the woofer XO changing the iron core coil to air core. I will measure the resistance of the old coil and buy a gage air coil that has similar resistance.

Basics of those I get but not the shunt with the coil on the tweeter. Which brings me back to few questions that came up when reading your reply:
- You have changed the coil from 22ga to 14ga. I have not measuered the old coil yet, but I believe it is even thiner than 22ga. But I am not planning to go that far as 14ga.
Anyhow, you stated the following on the changes:
1." Reducing coil DCR will make the tweeter sound louder".
I thought that lowering resistance on the "active" wire will make woofer/tweeter louder, not the resistance on the shunt connected to the "null" wire.

2. "Audiophile perspective would say it's more detailed"
Detail and precision is currently what I am aiming for. My assumtion about the shunt (2nd order) is that it filters out further unwanted frequencies, logically I would say that the lower resistance there the better, but ... there is more than meets the eye. I just do not know what.


I will need to read about the design and all about speakers. Any suggestions on books? I heard about the "Loudspeaker Design Cookbook" by Vance Dickason and "Designing, Building, and Testing Your Own Speaker System with Projects" from David Weems.
I know that best is to test for my self and see how each component behaves and what effect does it have in overall. I will need to buy a lot of cheap resistors as the shunt coil upgrade is happening and fine tuning can  begin.  :wink:

richidoo

1." Reducing coil DCR will make the tweeter sound louder".
I thought that lowering resistance on the "active" wire will make woofer/tweeter louder, not the resistance on the shunt connected to the "null" wire.

Sorry! Yes you are correct! A short would mute, so reducing shunt resistance decreases output level.

Quote
2. "Audiophile perspective would say it's more detailed"
Detail and precision is currently what I am aiming for. My assumtion about the shunt (2nd order) is that it filters out further unwanted frequencies, logically I would say that the lower resistance there the better, but ... there is more than meets the eye. I just do not know what.


The filter function is not changed with lower resistance coil. Inductance is the same so it still corners at the same freq with same slope. Resistance change is very small, it's still copper conductor. I understand your question, will 22ga have same electrical damping as 14ga + resistor? Technically yes, damping should be the same. I did not add resistor when I upgraded tweeter coil and I got more detail and still measures correctly, but I jumped from 22 to 14. And it did not make the tweeter sound more attenuated.

In upgrading tweeter resistors from metal oxide to wirewound (as you plan to do) I found the added detail the wirewound made me attenuate tweeter a little more to achieve balanced sound with the more detail. The better harmonic complexity and textural detail remained even after increasing attenuation on the tweeter network without adding the DCR resistor. YMMV, you have to try it and see, this is about taste, custom tuned xo. I am more music lover than audiophile, avoiding listening fatigue is higher priority for me than getting more detail. But ironically, often they go together as distortion is reduced in general.

Quote
I will need to read about the design and all about speakers. Any suggestions on books? I heard about the "Loudspeaker Design Cookbook" by Vance Dickason and "Designing, Building, and Testing Your Own Speaker System with Projects" from David Weems.
I know that best is to test for my self and see how each component behaves and what effect does it have in overall. I will need to buy a lot of cheap resistors as the shunt coil upgrade is happening and fine tuning can  begin.  :wink:

Those are good books. Also read the technical forums and articles online.
Best thing is to make friends with local speaker builders and let them help you with design choices and xo tuning.
Where do you live?

gringo117

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In upgrading tweeter resistors from metal oxide to wirewound (as you plan to do) I found the added detail the wirewound made me attenuate tweeter a little more to achieve balanced sound with the more detail. The better harmonic complexity and textural detail remained even after increasing attenuation on the tweeter network without adding the DCR resistor.

How did you do that? I mean increasing attenuation on the tweeter network without adding the DCR resistor.

I am from Slovakia.  Asking more complex question on this forum was/is a bit premature, as I understand a half of it, if anything. Also getting in touch with others around here (Slovakia) relates to it. When I am asked a not simple question I expect the other side to understand the basics and vice versa.
At least that is what courtesy expects of me. Therefore until I am not comfortable with the elementary things, why bother others.
This post was an exception as I was very curious and could not  find an answer anywhere. But it already helped me and I found out, thanks to you, where and how to search for answers.  :)

FullRangeMan

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Welcome  :thumb:

ArthurDent

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Greetings & Welcome to AC gringo   :thumb:

gringo117

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Thank you FullRangeMan and Arthur.  :)

FullRangeMan

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Hi,
In the 1990s I noted car audio guys used to paint mate black inside its car sub boxes to tame hi freq and up the bass, I noted they also used a brown felt from car hood to stuffing the box, so I used these in my next DIY speaker and was stunned with the results.
https://www.audiocircle.com/index.php?topic=100689.0