Jonnravn:
Nobody has answered your question in a couple of days. I do not know the answer myself. However, I have a suggestion.
Perhaps a better way to pose the question might be to state how big a box volume you want and what frequency you want to tune it to. Some people just keep adding weight until the proper tuning of the box is reached as measured by the impedance dip at resonance. They might not even know the exact weight, but they might have built the box you are looking to build.
Try giving us your desired box volume and frequency of tuning. See if anyone responds.
LOL, you live in Denmark and you can't get an answer to that question just by asking around? Hmmm...
Nobody has answered your question in a couple of days. I do not know the answer myself. However, I have a suggestion.
Perhaps a better way to pose the question might be to state how big a box volume you want and what frequency you want to tune it to. Some people just keep adding weight until the proper tuning of the box is reached as measured by the impedance dip at resonance. They might not even know the exact weight, but they might have built the box you are looking to build.
Try giving us your desired box volume and frequency of tuning. See if anyone responds.
LOL, you live in Denmark and you can't get an answer to that question just by asking around? Hmmm...
Jonnravn:
You made clear in your first post that you have no problem calculating the weight of the passive radiator.
What I was saying was this. There are two ways to build a passive radiator box.
One way is to decide what your box volume and tuning frequency is, then calculate how much weight to add to the passive radiator. This seems to be the approach you are taking.
The other way is to build your box to the desired volume, then keep adding wieght to the passive radiator until the desired tuning frequency is reached as measured by the impedance dip at the frequency of resonance. The people who use this method often do not even know how much weight they have added. They only know that they have added enough weight to bring the box to the desired frequency of resonance.
My suggestion was for you to determine what your desired box volume and tuning frequency is, then post the results. The XLS is a very popular speaker, and there might well be someone who built one with the box volume and tuning resonance you desire, who had perfectly satisfactory results, but who really does not know how much weight he actually added.
I was not saying that you did not know how to calculate the weight. I was only saying that someone else who built a good-performing box might have added the weight you need for your box, but never bothered figuring out how much weight he added.
Just for the heck of it, what is the box volume and desired tuning for your XLS box? Perhaps someone here has built such a box without even knowing how much weight he added, but got the resonance frequency in the box volume he desired.
You made clear in your first post that you have no problem calculating the weight of the passive radiator.
What I was saying was this. There are two ways to build a passive radiator box.
One way is to decide what your box volume and tuning frequency is, then calculate how much weight to add to the passive radiator. This seems to be the approach you are taking.
The other way is to build your box to the desired volume, then keep adding wieght to the passive radiator until the desired tuning frequency is reached as measured by the impedance dip at the frequency of resonance. The people who use this method often do not even know how much weight they have added. They only know that they have added enough weight to bring the box to the desired frequency of resonance.
My suggestion was for you to determine what your desired box volume and tuning frequency is, then post the results. The XLS is a very popular speaker, and there might well be someone who built one with the box volume and tuning resonance you desire, who had perfectly satisfactory results, but who really does not know how much weight he actually added.
I was not saying that you did not know how to calculate the weight. I was only saying that someone else who built a good-performing box might have added the weight you need for your box, but never bothered figuring out how much weight he added.
Just for the heck of it, what is the box volume and desired tuning for your XLS box? Perhaps someone here has built such a box without even knowing how much weight he added, but got the resonance frequency in the box volume he desired.
Here is a fellow who used two 12" versions of the Peerless Passive Radiator massed to 790 grams each-that is 28 oz, or nearly two pounds.
It seemed to work well for him.
Perhaps two pounds is not out of the question for Peerless Passive Radiators.
http://www.geocities.com/adrian_mack/
It seemed to work well for him.
Perhaps two pounds is not out of the question for Peerless Passive Radiators.
http://www.geocities.com/adrian_mack/
Here is something via Google. Apparently the answer is 625 grams, (22 ounces), can be added.
These two links to a single thread on diysubwoofers seems to provide the answer. Adrian Mack, the fellow with the above webpage, is one of the posters.
http://www.diysubwoofers.org/talkshop/messages/15818.htm
http://www.diysubwoofers.org/talkshop/messages/15878.htm
These two links to a single thread on diysubwoofers seems to provide the answer. Adrian Mack, the fellow with the above webpage, is one of the posters.
http://www.diysubwoofers.org/talkshop/messages/15818.htm
http://www.diysubwoofers.org/talkshop/messages/15878.htm
Thanx for all you help!
I have tried contacting both DST and Peerless and some of their Danish distributors. and nobody seems to want to help me! (So it is great to find forums like this where people, like yourself, help each other).
The box is going to be a 35 Liter box (that is when everything is installed, before installation it will be, around 42 Liters). that means a box with outside mesurements of 40*40*40cm (think it's around 16*16*16 inches).
I have tried contacting both DST and Peerless and some of their Danish distributors. and nobody seems to want to help me! (So it is great to find forums like this where people, like yourself, help each other).
The box is going to be a 35 Liter box (that is when everything is installed, before installation it will be, around 42 Liters). that means a box with outside mesurements of 40*40*40cm (think it's around 16*16*16 inches).
Jonnravn said:
I was afraid of that.
Before Peerless was taken over by Danish Sound Technologies, they had their own Email address for support. I sent a question to that Email address and received an answer within two days.
After Peerless was taken over by Danish Sound Technologies, they changed the policy to where the Emails for all support have to go to the distributor for your area. I Emailed the distributor with my question. Know what my question was? Which Peeerless models have the aluminum shorting ring in their magnet systems. Not a tough one, don't you agree? I Emailed them this rather straightforward question over a year ago, and have yet to receive an answer.
As a general rule, in any industry, when the company tells you to contact the distributor for an answer to your technical question, that is usually another way of saying "Go away". Distributors are people who are interested in getting sales forces together and shipping schedules, not answering individual tech questions. Their operations do not have engineering offices where the tough questions can be obtained by the tech help. I have had bad experiences in several industries with distributors.
If you want, I can call Madisound or Parts Express tech help with any other tech question you have, since this question appears to be answered. It's a free call over here. I have had good experiences with the tech help in both companies, and it is possible that, with the large volume of Peerless that they sell, a question from either of these two companies directed to Peerless will actually be answered by Peerless' engineering department. Volume = clout.
Well, they're a sorry bunch! OK then, according to this application note: http://www.wescomponents.com/peerless/XLS.htm they had no problem massing their 10" PR to 600g, and in general, the amount of weight the suspension can handle is proportional to its circumference, so.....
The effective circumference of the 12" PR is ~1.183x the 10", x600 = ~710g. This falls ~in line with Adire's 1Kg limit for their 15" so I would be comfortable with it. Beyond this point and you'll have to take a hard look at how much it's likely to be energized. If it's tuned so low that it only moves a few mm and there's some EQ to filter out the signal below Fb (just in case), then it should be able to handle ~1.5x 710 = ~1065g based on my own experiments with the Adire 15" and ServoDrive 18" PRs.
As always though, YMMV, so caveat emptor.
GM
The effective circumference of the 12" PR is ~1.183x the 10", x600 = ~710g. This falls ~in line with Adire's 1Kg limit for their 15" so I would be comfortable with it. Beyond this point and you'll have to take a hard look at how much it's likely to be energized. If it's tuned so low that it only moves a few mm and there's some EQ to filter out the signal below Fb (just in case), then it should be able to handle ~1.5x 710 = ~1065g based on my own experiments with the Adire 15" and ServoDrive 18" PRs.
As always though, YMMV, so caveat emptor.
GM
Jonnravn said:
Well, the plot thickens, (but it has a happy ending for users of single PR systems, as opposed to those who would use two in one box). I am no longer so convinced that you can add 625 grams to any Peerless Drone Cone, (the original name for the Passive Radiator, coined by it's inventor, Harry Olson). That is because the 12" Peerless Passive Radiator comes in three different weights with 3 different Peerless numbers. They all have the same suspension-so how can 625 grams be the most you can add for all three?
Here are the three 12" Passive Radiators that Peerless offers:
830547: 290g, Fs=12.6 Hz, available in America at Parts Express, PE# 297-610
830548: 425g, Fs=10.4 Hz, the one listed on the Peerless website and available in America at Madisound and Speaker City. It is probably also the one offered by most Perless dealers worldwide.
830549: 625g, don't know the Fs. Got number from Peerless App Note, (more on that momentarily).
Here are two versions of the Peerless 10" Passive Radiator:
830468: 265g, Fs=13.7 Hz Available in america at Parts Express, PE# 297-606
830481: 400g, Fs=11.2 Hz.
Before this looks hopeless, let me point out that Peerless has on it's website three application notes dealing with the XLS series in three enclosures-closed box, vented and Drone Cone. Guess what? The enclosure using the 12" Drone cone is 35 liters-exactly your size. so this should spell it all out for you. Here is the page with the Application Notes:
http://www.d-s-t.com/main/index.htm
Or else just go to www.peerless.dk, click "Enter" then click "Engineering".
I told you there was a happy ending!
You did not mention if you planned to use the Peerless XLS driver in the enclosure you are building, just the Passive Radiator. Also, is it possible that you are using the 10" XLS driver and the 12" Passive Radiator? That is very common and very recommended-having the Passive Radiator larger than the driver. The Peerless Passive Radiators have an Xmax twice that of the XLS drivers, so you can get away with using the same size for both driver and Passive Radiator. But larger is always better. that is why some people use two Drone Cones per box.
At any rate, if you do use a different driver, or use a 10" XLS driver in a box with a 12" Passive Radiator, the box tuning will remain the same as the in the Application Note. The box response will likely change.
As for being skeptical about 625g being okay to add to any Peerless Passive Radiator, (even though Audio Asylum quoted a Peerless Tech Support person writing just that), it is because 625g just happens to be the weight of the heaviest Passive Radiator that Peerless sells. This could mean one of several things:
A) The 625 grams is meant to be added to the lightest PR that Peerless sells-the one with 290 grams;
B) It is meant to be added to the most common PR that Peerless sells-the one with 425g;
C) Peerless conducted tests and found that it just so happens that the weight limit is about twice what the weight of the heaviest PR they sell-the one with 625 grams.
D) The Peerless Tech could have asked, (or thought he had asked), the Peerless Engineer how much weight you can add to the PR, and the Engineer answered how much weight the PR can handle in total-that is, the weight it comes with and weight added by the builder.
To be honest, I think (D) is the most likely possiblity.
At any rate, your 35 liter box will be tuned to 20 Hz by a 625g 12" Peerless PR, and for sure that has to be as low or lower than you want to go. So you are all set. Moreover, the Application Notes both give examples of exceptionally small boxes for the XLS drivers, (would you consider putting a 12 incher in a box smaller than 1¼ Ft³ and expect any deep bass out of it?), so boxes with one PR per box are essentially covered. The larger the box, the lighter the PR has to be for the same tuning, so overweighting is not an issue for boxes larger than than the Application Note examples.
For boxes with two PR's per box, the story is still unresolved. Adrian Mack, (see post # 6), weighted his Peerless PR's, (two to a box) at 790 grams. However, that is only about 25% heavier than Peerless' heaviest PR, so maybe he was just going a little past the limits and getting away with it.
Hmmm, I might give Madisound Tech help a call Tuesday just to clear this up. The XLS is a very popular speaker, and I have seen more than one reference on the net to where someone has used two PR's per box. This might need investigating.
A) The 625 grams is meant to be added to the lightest PR that Peerless sells-the one with 290 grams;
B) It is meant to be added to the most common PR that Peerless sells-the one with 425g;
C) Peerless conducted tests and found that it just so happens that the weight limit is about twice what the weight of the heaviest PR they sell-the one with 625 grams.
D) The Peerless Tech could have asked, (or thought he had asked), the Peerless Engineer how much weight you can add to the PR, and the Engineer answered how much weight the PR can handle in total-that is, the weight it comes with and weight added by the builder.
To be honest, I think (D) is the most likely possiblity.
At any rate, your 35 liter box will be tuned to 20 Hz by a 625g 12" Peerless PR, and for sure that has to be as low or lower than you want to go. So you are all set. Moreover, the Application Notes both give examples of exceptionally small boxes for the XLS drivers, (would you consider putting a 12 incher in a box smaller than 1¼ Ft³ and expect any deep bass out of it?), so boxes with one PR per box are essentially covered. The larger the box, the lighter the PR has to be for the same tuning, so overweighting is not an issue for boxes larger than than the Application Note examples.
For boxes with two PR's per box, the story is still unresolved. Adrian Mack, (see post # 6), weighted his Peerless PR's, (two to a box) at 790 grams. However, that is only about 25% heavier than Peerless' heaviest PR, so maybe he was just going a little past the limits and getting away with it.
Hmmm, I might give Madisound Tech help a call Tuesday just to clear this up. The XLS is a very popular speaker, and I have seen more than one reference on the net to where someone has used two PR's per box. This might need investigating.
>I am no longer so convinced that you can add 625 grams to any Peerless Drone Cone, (the original name for the Passive Radiator, coined by it's inventor, Harry Olson). That is because the 12" Peerless Passive Radiator comes in three different weights with 3 different Peerless numbers. They all have the same suspension-so how can 625 grams be the most you can add for all three?
====
The values I suggested are total weights, so subtracting the weight of the particular version from these numbers would be the max that can be added. I assume they offer different ones for the same reason Adire, Lambda, and Stryke originally did, so that the amount of added weight required could be minimized. Not all apps need heavy PRs.
Anyway, Peerless doesn't say how much can be added, we just know they offer up to a 625g version. Regardless, how much can be added is a function of excursion, limit it and the weight can go up considerably. What would be nice to know is the total weight it can safely handle at max excursion. I'm comfortable with my guesstimate, but it would be nice to know for sure.
Actually, if I were using it in a design I would use a bit higher limit, 752g, based on its circumference/other's PR specs/experience.
GM
====
The values I suggested are total weights, so subtracting the weight of the particular version from these numbers would be the max that can be added. I assume they offer different ones for the same reason Adire, Lambda, and Stryke originally did, so that the amount of added weight required could be minimized. Not all apps need heavy PRs.
Anyway, Peerless doesn't say how much can be added, we just know they offer up to a 625g version. Regardless, how much can be added is a function of excursion, limit it and the weight can go up considerably. What would be nice to know is the total weight it can safely handle at max excursion. I'm comfortable with my guesstimate, but it would be nice to know for sure.
Actually, if I were using it in a design I would use a bit higher limit, 752g, based on its circumference/other's PR specs/experience.
GM
That is true. After all this checking on websites, poring over Application Notes, and reading direct quotes from Peerless Techs, basically all we really know for sure is that Peerless sells a PR wieghted as much as 625, and might or might not be weighted some more.GM said:
LOL, with Jonnravn, that makes at least three of us who would like to know for sure from Peerless.GM said:
GM said:
725g is only 16% over 625g, which Peerless sells. So it probably is a safe bet, especially if Adrian Mack is having success at 790g. I'm sure that any limit Peerless gives doesn't imply that going a little over means swift destruction. But like you said, it sure would be nice to find what what Peerless actually says.
Incidentally, about those different PR numbers. The Parts Express page says there is a threaded M5 hole to use as weighting. I would guess that the only difference between the three Peerless PR's is that the lightest one has an empty threaded hole for a bolt, and the two heavier ones have a bolt in them. So looking for dealers for your correct Peerless PR number probably doesn't make any sense. Just add the correct weight bolt. How heavy a bolt you can add, of course, is the question of this thread.
The bolt hole is so you can add washers, etc. to the basic mass plug. They probably have them for sale separately, I didn't look. I prefer the Adire, ServoDrive, etc., units. They have a cardboard tube that you can load whatever you want into them. I used clay with lead fishing weights mixed in.
GM
GM
I actually started my Subwoofer project by reading the aplication note from peerless (so the size of 35 liters, is not just taken out of thin air ).
at first I was going to build a sub just like the one in the aplication note. but I was not satisfied with the fact that the sub drops almost 6 DB from 100Hz to 30Hz. I fund that using 2 passive radiators with a weight around 675-700 grams a piece, would make the sub drop only about 2.5-3 DB from 100 to 30Hz.
it seems that if i use a highpass filter with a cutoff frequency of around 20Hz, I will not get into to much trouble with the max excurtion of the units
All drivers are 12" and the amplifier is a 400 Watts digital subwoofer amp. (same one as Jamo uses in there D8 sub.)
).at first I was going to build a sub just like the one in the aplication note. but I was not satisfied with the fact that the sub drops almost 6 DB from 100Hz to 30Hz. I fund that using 2 passive radiators with a weight around 675-700 grams a piece, would make the sub drop only about 2.5-3 DB from 100 to 30Hz.
it seems that if i use a highpass filter with a cutoff frequency of around 20Hz, I will not get into to much trouble with the max excurtion of the units
All drivers are 12" and the amplifier is a 400 Watts digital subwoofer amp. (same one as Jamo uses in there D8 sub.)
Well, I feel pretty comfortable with GM's estimates, especially since Adrian Mack, who seems to know what he is doing, exceeded them and seems pleased with the results.
Also, other Passive Radiators seem to be rated for 1,000g or more.
Just for the heck of it, though, at this point I really am interested in what Peerless has to say.
I'll give a call to Madisound this week and see what they say. It is very observant of you to note a +3 dB difference at a frequency by doubling the Passive Radiator area. I tried that with other programs and I did not get the same results-I used Bullock and White's freeware. I should check it on Subwoofer Simulator, a program written by our own F4ier.
I always felt intuitively that the larger the Drone Cone area with the same tuning, the greater the efficiency. But I never received any verification on this.
If worse comes to absolute worst, you can always make the box a bit larger while keepting the PR weight the same. That will lower the box tuning frequency.
Also, other Passive Radiators seem to be rated for 1,000g or more.
Just for the heck of it, though, at this point I really am interested in what Peerless has to say.
I'll give a call to Madisound this week and see what they say. It is very observant of you to note a +3 dB difference at a frequency by doubling the Passive Radiator area. I tried that with other programs and I did not get the same results-I used Bullock and White's freeware. I should check it on Subwoofer Simulator, a program written by our own F4ier.
I always felt intuitively that the larger the Drone Cone area with the same tuning, the greater the efficiency. But I never received any verification on this.
If worse comes to absolute worst, you can always make the box a bit larger while keepting the PR weight the same. That will lower the box tuning frequency.
>I fund that using 2 passive radiators with a weight around 675-700 grams a piece, would make the sub drop only about 2.5-3 DB from 100 to 30Hz.
====
Hmm, how did you arrive at this 'pie-in-the-sky' gain? This assumes that one PR is compressing, but it's not since it represents a low vent 'speed' already. Dual PRs lowers vent 'speed', reducing excursion, and rocking coupling motion if laid out as bipolar. These make it worth the extra $$ IMO since group delay is better than sealed in the passband.
GM
====
Hmm, how did you arrive at this 'pie-in-the-sky' gain? This assumes that one PR is compressing, but it's not since it represents a low vent 'speed' already. Dual PRs lowers vent 'speed', reducing excursion, and rocking coupling motion if laid out as bipolar. These make it worth the extra $$ IMO since group delay is better than sealed in the passband.
GM
I believe it was Deon Bearden who claimed this, but AFAIK no one's been able to duplicate his measurements, I know I certainly haven't. Think of it this way, the PR is the equivalent of a tube vent of whatever its cross sectional area and the 'length' required for the desired Fb in the form of added mass. Due to its extreme size, vent speed, ergo acoustic compression, will be ~non-existant if the PR is at least as large as the main driver (it should be at least 1.5-2x for best performance since it needs to displace much more air than the main driver), so if two are used, whatever this is gets cut in half, but one half of something already inaudible.........
You want wide BW gain from a single driver in the LF will require a huge horn.
GM
You want wide BW gain from a single driver in the LF will require a huge horn.
GM
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.