[hans030390]

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Nice to see some new ideas on this thread!
 
Love to see some of you guys turning the ol' gears within the noggin'!
 

 
Does this mean we're on the right track?

 
When people first started mentioning sound diffusion for the T50RP in September/October, I actually wanted to try something much like I just did with the cardboard based off reading I had done and pictures I'd seen of sound diffusers. Problem is, I couldn't think of a good way to do it! I can't believe it took proid mentioning his resonator to make me remember that, hey, the interior section of cardboard might be a simple way to try it out! Looking back, it seems so obvious and simple...

 

[wje]

My T20RP MKIIs arrived today from BH Photo.  I have some other activities to get to tonight, but I'll at least open them up and see what they're about.
 
Meanwhile, for those lovers of the stock T50RP cables, I have two for sale if you'd like to buy them.  

 ... and, probably three of them after I look over the T20RPs.

 

[BlackbeardBen]

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There have been some talks about tuning, though not for the T50RP specifically. For now, I think it's a "testing the waters" kind of thing. If this type of mod catches on, I'm sure we'll see more people discussing specific tuning and tweaking.
 

I don't see how this can possibly "catch on" when the entire point of the Helmholtz resonator is to tune it to absorb one specific frequency band.
 
It is entirely pointless to use a Helmholtz resonator if you're not doing the math (or if you're a masochist bent on doing things backwards, guessing and checking through measurements) to construct a Helmholtz resonator tuned to the specific frequency band you want to affect (and its peak and Q).
 
You don't try to build a house through guess and check - or worse, guess and no check - do you?

 

[hans030390]

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I don't see how this can possibly "catch on" when the entire point of the Helmholtz resonator is to tune it to absorb one specific frequency band.
 
It is entirely pointless to use a Helmholtz resonator if you're not doing the math (or if you're a masochist bent on doing things backwards, guessing and checking through measurements) to construct a Helmholtz resonator tuned to the specific frequency band you want to affect (and its peak and Q).
 
You don't try to build a house through guess and check - or worse, guess and no check - do you?

Again, I think proid was more worried about testing his idea and putting the idea out here rather than getting the tuning just right. As soon as he mentioned it, some people started discussing how they might be able to tune them (vaguely). What does that show you? Once the idea is out there, people will try to maximize the idea for its specific purpose (in this case, Helmholtz resonators in the T50RP). The idea is already catching on to some degree. Would you rather that he mention the Helmholtz resonator without tuning or not mention it at all because he didn't tune it specifically for the T50RP? I don't know about you, but, "entirely pointless" or not, I'm glad proid mentioned the idea!
 
Also consider that the vast majority of members here probably wouldn't even know where to start when tuning a Helmholtz resonator. As simple as the math may be (I wouldn't know. I haven't looked.), not everyone has strong math skills.
 
Keep in mind that the majority of mods for the T50RP didn't come about from specific tuning or objective data. Yes, some people have measurement systems to more objectively test their mods, but the modding process so far has been overwhelmingly based on subjective impressions and trial-and-error. So far, no one seems to have died, and people are generally happy with the sound their modded T50RP produces.
 
Here's a suggestion. Instead of posting on here with an incredibly critical attitude, why don't you be more helpful and tune the Helmholtz resonator yourself if it bothers you so much? You apparently know exactly what you're talking about. Also, the house building analogy is horrible.
 
 

 

[BlackbeardBen]

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Again, I think proid was more worried about testing his idea and putting the idea out here rather than getting the tuning just right. As soon as he mentioned it, some people started discussing how they might be able to tune them (vaguely). What does that show you? Once the idea is out there, people will try to maximize the idea for its specific purpose (in this case, Helmholtz resonators in the T50RP). The idea is already catching on to some degree. Would you rather that he mention the Helmholtz resonator without tuning or not mention it at all because he didn't tune it specifically for the T50RP? I don't know about you, but, "entirely pointless" or not, I'm glad proid mentioned the idea!
 
Also consider that the vast majority of members here probably wouldn't even know where to start when tuning a Helmholtz resonator. As simple as the math may be (I wouldn't know. I haven't looked.), not everyone has strong math skills.
 
Keep in mind that the majority of mods for the T50RP didn't come about from specific tuning or objective data. Yes, some people have measurement systems to more objectively test their mods, but the modding process so far has been overwhelmingly based on subjective impressions and trial-and-error. So far, no one seems to have died, and people are generally happy with the sound their modded T50RP produces.
 
Here's a suggestion. Instead of posting on here with an incredibly critical attitude, why don't you be more helpful and tune the Helmholtz resonator yourself if it bothers you so much? You apparently know exactly what you're talking about. Also, the house building analogy is horrible.
 
 

It's not just "tuning" a Helmholtz resonator as in you're automatically close - it's "tuning" as in you have no idea at all what frequency band is going to be impacted, if at all, and what factors affect the tuning.
 
This isn't an entirely unestablished area of acoustics - the Helmholtz resonator is more like the sniper rifle of acoustic tuning, not the artillery that is bass traps, mass loading, or bracing an enclosure.  You can't just spray and pray - if you start in the wrong spot, there's no guarantee you're even going to get anywhere close.
 
That's what my beef is.  I'm not saying it's bad to experiment - only that with such a specific tool it's at best a poor use of your time to skip the math and at worst may be very misleading in that you may attribute results to the wrong causation.  I don't mean to come off as harsh; it's just that it's a fair amount more complicated than typical mods.
 
I would in fact like to do some more comprehensive reading regarding the design of Helmholtz resonators - unfortunately right now I'm preparing for a business trip and it'll be some time before I have any time to dedicate to this.
 
As far as the idea's popularity - it seems to me like people are just taking the "cardboard" part of this and running, mostly ignoring the entire Helmholtz resonator concept.  Even the originator of the idea hasn't made clear exactly what he put in his T50RP (to me anyway, maybe I missed something).

 

[satwilson]

Back to the soldering thing...didn't anyone read the post by MrSpeakers...."cut the stock wiring about 1" from the stock soldering joint at the traces" and solder to your hearts content" Paraphrase....What are you guys doing????? This was just a few days ago...

 

[LFF]

 

[wje]

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Back to the soldering thing...didn't anyone read the post by MrSpeakers...."cut the stock wiring about 1" from the stock soldering joint at the traces" and solder to your hearts content" Paraphrase....What are you guys doing????? This was just a few days ago...

To add to what you've posted, I also believe it's a good idea to use some epoxy to adhere the wires to the outer edge of the driver.  This will prevent the wires themselves from tugging on the solder joint and solder point - possibly, causing damage.  If you don't use a bit of epoxy, you have to be real careful taking the cups apart and putting them back together with the  3 or 4 inches of slack wire hanging from the cups and mounted to the driver.
 
Though I'm going to use the aluminum solder next time and still keep on applying my own wire to the solder dots.  I just prefer having the Fostex 'phones free of the wire they use - it seems like solid core bell wire, if I'm not mistaken.  If you bend and move it too many times, you'll probably snap it at some point.
 

 

[proid]

In fact, when i first read about Helmholtz resonator, i also read about how to caculate the frequency it absorb: http://www.google.com.vn/url?sa=t&rct=j&q=helmholtz%20resonator%20calculator&source=web&cd=6&ved=0CGEQFjAF&url=http%3A%2F%2Fwww.sae.edu%2Freference_material%2Fimages%2Fcontent%2FHelmholtz.xls&ei=92BET8PQELCPiAer5dWbAw&usg=AFQjCNFnmznWtaFGD_kwH6BEIq8Ea75wcw&cad=rja
But again, with this caculation, it seem like i can never absorb the most low frequency because the cup is too small, there isn't enough space to make "right" resonator to absorb 20, 30hz... But it's the most effective way to absorb low frequency, it's must be better than fiberglass, so i tried it and you know, it work. Although i'm not sure what's the specific frequency my resonator absorb but with the calculation, i know how to make it absorb low frequency better: reduce slot width, increase slat width, slat depth, depth from wall. I also tried stuffing fiberglass in the resonator but it didn't work that way, bass was muddy.

 

[Magick Man]

Meh, I just did the cardboard that way in the D2000 to help cut back on high frequency reflections, maybe tame a little of the worst sibilance. For whatever reason, it worked, so I'm happy.

BTW, the yellow "stuff" is 2mm foam matting. I tried 80mil Fatmat and it tightened my mid and upper bass but killed my sub-bass, the foam sheets aren't as extreme and don't do that. Then I went around the inside edge with some yellow Plasticine and then glued down my cardboard diffuser.

 

[satwilson]

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To add to what you've posted, I also believe it's a good idea to use some epoxy to adhere the wires to the outer edge of the driver.  This will prevent the wires themselves from tugging on the solder joint and solder point - possibly, causing damage.  If you don't use a bit of epoxy, you have to be real careful taking the cups apart and putting them back together with the  3 or 4 inches of slack wire hanging from the cups and mounted to the driver.
 
Though I'm going to use the aluminum solder next time and still keep on applying my own wire to the solder dots.  I just prefer having the Fostex 'phones free of the wire they use - it seems like solid core bell wire, if I'm not mistaken.  If you bend and move it too many times, you'll probably snap it at some point.
 

I agree, securing the wires with epoxy to secure the solder joint is mandatory for multiple/mod/openings. I also think your permatex repair, post#6530, is the best for those "who blew it". However my stock wiring is stranded, and once secured....you don't have to worry aluminum/tin lead, "blowing it". I understand anyones preference, free of the wire they use, etc, however IMHO MrSpeakers is right, compared to the traces..your wire, their wire, doesn't matter.
 
 

 

[satwilson]

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I like popcorn too, some people read the "posts/thread." Some people just post...thanks
 
 

 

[hans030390]

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It's not just "tuning" a Helmholtz resonator as in you're automatically close - it's "tuning" as in you have no idea at all what frequency band is going to be impacted, if at all, and what factors affect the tuning.
 
This isn't an entirely unestablished area of acoustics - the Helmholtz resonator is more like the sniper rifle of acoustic tuning, not the artillery that is bass traps, mass loading, or bracing an enclosure.  You can't just spray and pray - if you start in the wrong spot, there's no guarantee you're even going to get anywhere close.
 
That's what my beef is.  I'm not saying it's bad to experiment - only that with such a specific tool it's at best a poor use of your time to skip the math and at worst may be very misleading in that you may attribute results to the wrong causation.  I don't mean to come off as harsh; it's just that it's a fair amount more complicated than typical mods.
 
I would in fact like to do some more comprehensive reading regarding the design of Helmholtz resonators - unfortunately right now I'm preparing for a business trip and it'll be some time before I have any time to dedicate to this.
 
As far as the idea's popularity - it seems to me like people are just taking the "cardboard" part of this and running, mostly ignoring the entire Helmholtz resonator concept.  Even the originator of the idea hasn't made clear exactly what he put in his T50RP (to me anyway, maybe I missed something).

Hey, I just think it's fun to try out different things with my T50RP. For now, I can only use my ears as the judge. I'd like to eventually set up a basic measurement rig. I don't mind a trial-and-error approach.
 
As for my particular usage of the cardboard, I was going for a very basic acoustic diffuser rather than a Helmholtz radiator. Initial listening tests sound good, and I think I hear more sub-bass. Could be wrong. Either way, I'm enjoying it.
 

 

[wje]

I found a pretty interesting article / procedure on DIY Audio in regards to soldering aluminum with regular solder.  Apparently, the key is to prevent the aluminum oxide from building up, which appears to be one P.I.T.A. when soldering aluminum.
 
http://www.diyaudio.com/forums/planars-exotics/197412-soldering-aluminium.

 

[iowercase]

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In fact, when i first read about Helmholtz resonator, i also read about how to caculate the frequency it absorb: http://www.google.com.vn/url?sa=t&rct=j&q=helmholtz%20resonator%20calculator&source=web&cd=6&ved=0CGEQFjAF&url=http%3A%2F%2Fwww.sae.edu%2Freference_material%2Fimages%2Fcontent%2FHelmholtz.xls&ei=92BET8PQELCPiAer5dWbAw&usg=AFQjCNFnmznWtaFGD_kwH6BEIq8Ea75wcw&cad=rja
But again, with this caculation, it seem like i can never absorb the most low frequency because the cup is too small, there isn't enough space to make "right" resonator to absorb 20, 30hz... But it's the most effective way to absorb low frequency, it's must be better than fiberglass, so i tried it and you know, it work. Although i'm not sure what's the specific frequency my resonator absorb but with the calculation, i know how to make it absorb low frequency better: reduce slot width, increase slat width, slat depth, depth from wall. I also tried stuffing fiberglass in the resonator but it didn't work that way, bass was muddy.

Color me naive, but when I enter in some guesstimates of what a cardboard resonator's dimensions are, I get frequencies back ranging from 6-10k.  Which is actually ideal to me since it's the 10k peak and 6-8k sibilance I'm interested in subduing, but I have a feeling I'm missing something critical with my guesses.  Example: slot width .2mm (x-acto slice), slat width 5mm (width of a cell), wall depth 3mm (depth of a cell), slat depth .5mm (thickness of the cardboard itself) = 8020Hz.