Hi all
I'm on the way to design my first loudspeaker, and I've learned here how to make an XO, calculate the cabinet size according to T/S params...
But I realise that the most basical rules aren't easy to find (maybe I'm the only one that ignore them
)
So, why not putting all those rules in one thread?
I'm looking for thinks like:
-magical numbers, those L/D/H ratios that give best results (are thos internal dimantions ratios, or external ones?)
-how much a tweeter must be offseted from bafle's center
-distance between a tweeter and a midrange (or midbass)
-time alignment/accoustical centers alignment
-optimal height for tweeters/midranges/woofers
-optimal place for a BR port or a TL port (front, rear, at the top or near the floor)
-bafle step compensation
-standing waves
-edge rounding
-...
what do you all think about this?
Alex
I'm on the way to design my first loudspeaker, and I've learned here how to make an XO, calculate the cabinet size according to T/S params...
But I realise that the most basical rules aren't easy to find (maybe I'm the only one that ignore them
)So, why not putting all those rules in one thread?
I'm looking for thinks like:
-magical numbers, those L/D/H ratios that give best results (are thos internal dimantions ratios, or external ones?)
-how much a tweeter must be offseted from bafle's center
-distance between a tweeter and a midrange (or midbass)
-time alignment/accoustical centers alignment
-optimal height for tweeters/midranges/woofers
-optimal place for a BR port or a TL port (front, rear, at the top or near the floor)
-bafle step compensation
-standing waves
-edge rounding
-...
what do you all think about this?
Alex
magic numbers and the such.
As far as magic dimensions go a lot of people say that the golden ratio is the key. In other words your dimensions would be 0.618 : 1 : 1.618 . Unfortunately this leaves an awfully ugly speaker. If you want a nice tower its just good to do multiples of that. Things to avoid are square cross sections and sides that are integer multiples of others. If you have construction skills of some sort you can even avoid rectangular prism interiors by making an angled baffle or an egg shaped interior.
As far as baffle diffraction goes there is a GREAT simulator out there. You can find it at the following site http://www.pvconsultants.com/audio/diffraction/downloadbds.htm
Its a little tough to learn at first, but once you get it down you can see the effect of a certain arrangement. Unfortunately I'm not sure if there is an ideal placement, but either way this can tell you what the arrangement you want will give you.
This also gives me a chance to not so shamefully (maybe... thats a stretch) show off my new towers. I did an angled baffle and used that simulator to pick where I wanted the drivers to be. I will hopefully be putting a black piano finish on these. I have a lot of experience painting metal (cars), so this will be an experiment for me.
As far as magic dimensions go a lot of people say that the golden ratio is the key. In other words your dimensions would be 0.618 : 1 : 1.618 . Unfortunately this leaves an awfully ugly speaker. If you want a nice tower its just good to do multiples of that. Things to avoid are square cross sections and sides that are integer multiples of others. If you have construction skills of some sort you can even avoid rectangular prism interiors by making an angled baffle or an egg shaped interior.
As far as baffle diffraction goes there is a GREAT simulator out there. You can find it at the following site http://www.pvconsultants.com/audio/diffraction/downloadbds.htm
Its a little tough to learn at first, but once you get it down you can see the effect of a certain arrangement. Unfortunately I'm not sure if there is an ideal placement, but either way this can tell you what the arrangement you want will give you.
This also gives me a chance to not so shamefully (maybe... thats a stretch) show off my new towers. I did an angled baffle and used that simulator to pick where I wanted the drivers to be. I will hopefully be putting a black piano finish on these. I have a lot of experience painting metal (cars), so this will be an experiment for me.
Attachments
..... and ........
I forgot something.
I am under the belief that the tweeter should be pointed at the listener because high frequencies to not disperse like lower frequencies. In other words its very sensitive to directivity. My tweeters were placed so that they would hit my ears on my couch placed 10 feet away. I have a very small angle of 6 degrees, so they are just below the listening height as it is... some high school trig can fill the gaps.
As for port placement it depends on whether you want to floor or wall load it. I personally prefer front loaded, but i have no scientific way to explain my placement. I merely needed a certain length, didn't want a curved pipe, and wanted at least 3 inches between the end of the pipe and the damping material at the back of the speaker. After that it pretty much placed itself.
brent
I forgot something.
I am under the belief that the tweeter should be pointed at the listener because high frequencies to not disperse like lower frequencies. In other words its very sensitive to directivity. My tweeters were placed so that they would hit my ears on my couch placed 10 feet away. I have a very small angle of 6 degrees, so they are just below the listening height as it is... some high school trig can fill the gaps.
As for port placement it depends on whether you want to floor or wall load it. I personally prefer front loaded, but i have no scientific way to explain my placement. I merely needed a certain length, didn't want a curved pipe, and wanted at least 3 inches between the end of the pipe and the damping material at the back of the speaker. After that it pretty much placed itself.
brent
Re: magic numbers and the such.
Too bad, none of theyr excell worksheets works on my computer 🙁
I've got office 2000, french version, and when I try to open something coming from pvconsultans, I got a message telling that the file is protected with a numerical protection unavailable with my language
breguetphile said:
Too bad, none of theyr excell worksheets works on my computer 🙁
I've got office 2000, french version, and when I try to open something coming from pvconsultans, I got a message telling that the file is protected with a numerical protection unavailable with my language
Re: ..... and ........
For the tweeter ofsetting, I rode (on Lynn Olsen's website I think, http://www.aloha-audio.com/) that it must be x far from a side, and 1.618x fom the other (but this has to be condirmed)
what is floor or wall loading? how does this sound?
your speakers look nice 🙂 Where can I find some infos about them?breguetphile said:
For the tweeter ofsetting, I rode (on Lynn Olsen's website I think, http://www.aloha-audio.com/) that it must be x far from a side, and 1.618x fom the other (but this has to be condirmed)
what is floor or wall loading? how does this sound?
info
They are completely of my own design so I haven't really documented them all that well. The following site has some info as well as a screenshot of the cad drawing i made for them. http://www.brentcastle.com/speakers it is not complete, but for the most part its pretty good. all the interior bracing was like a window pane. Damping material was a mixture of carpet padding and acoustic foam as well as some polyfill everywhere but between the braces where the port is.
The tweeter is offset 0.7 inches (1.78 cm). It uses the vifa d25-35 tweeter (aluminum dome) and vifa p17wj0008 6.5" woofer. The front baffle is two layers of 3/4" mdf (18 mm) and the rest is just one layer.
The interior is about 27.5 liters and while I originally liked using a port that tuned it to 45hz, the woofer has now seemed to break in and i can measure the peak there, where it flatlined originally. i have put the 43hz port in and it will be the one i permanently put in when i paint these.
A few of the xo values have been changed to not only attenuate the tweeter due to its higher sensitivity, but also to decrease the gain due to baffle diffraction.
I can most definitely notice a difference with the spikes on. My spikes are the 5/8" (16 mm) and I can most definitely tell a difference with them.
As far as a review of these speakers I think the mids are great, but its probably lacking in the highs department. The bass has seemingly improved and while I was originally gonna mate a sub with these, I do not believe I will now do so.
If you have any other questions I didn't address just holler.
brent
They are completely of my own design so I haven't really documented them all that well. The following site has some info as well as a screenshot of the cad drawing i made for them. http://www.brentcastle.com/speakers it is not complete, but for the most part its pretty good. all the interior bracing was like a window pane. Damping material was a mixture of carpet padding and acoustic foam as well as some polyfill everywhere but between the braces where the port is.
The tweeter is offset 0.7 inches (1.78 cm). It uses the vifa d25-35 tweeter (aluminum dome) and vifa p17wj0008 6.5" woofer. The front baffle is two layers of 3/4" mdf (18 mm) and the rest is just one layer.
The interior is about 27.5 liters and while I originally liked using a port that tuned it to 45hz, the woofer has now seemed to break in and i can measure the peak there, where it flatlined originally. i have put the 43hz port in and it will be the one i permanently put in when i paint these.
A few of the xo values have been changed to not only attenuate the tweeter due to its higher sensitivity, but also to decrease the gain due to baffle diffraction.
I can most definitely notice a difference with the spikes on. My spikes are the 5/8" (16 mm) and I can most definitely tell a difference with them.
As far as a review of these speakers I think the mids are great, but its probably lacking in the highs department. The bass has seemingly improved and while I was originally gonna mate a sub with these, I do not believe I will now do so.
If you have any other questions I didn't address just holler.
brent
What do you all think about this page, explaining time alignment?
http://www.geocities.com/kreskovs/TimeAligned1.html
http://www.geocities.com/kreskovs/TimeAligned1.html
AC is overrated unless you plan to design a speaker
box where the tweeter is a few feet from the midrange.
Get a tweeter and midrange and place it on your test bench
and offset the centers by an inch or two, tell me if it's audible,
... it's not...
Do the same test with tweeter and woofer. hehe
box where the tweeter is a few feet from the midrange.
Get a tweeter and midrange and place it on your test bench
and offset the centers by an inch or two, tell me if it's audible,
... it's not...
Do the same test with tweeter and woofer. hehe
For every Magic Design Rule, there are dozens of notable exceptions. For me, the most universal rules are trivial:
1. Map out clearly the design goal: frequency response, polar pattern (especially its variation with frequency), power handling...
2. Measure the hell out of the actual drivers you have. Don't rely on other people's data, especially the manufacturer.
3. Model, model, model.
4. Prototype and measure, measure measure.
5. Adjust until you hit your design target. Then listen, listen, listen to see if you picked your target well.
All other rules become less true as they become less trivial.
1. Map out clearly the design goal: frequency response, polar pattern (especially its variation with frequency), power handling...
2. Measure the hell out of the actual drivers you have. Don't rely on other people's data, especially the manufacturer.
3. Model, model, model.
4. Prototype and measure, measure measure.
5. Adjust until you hit your design target. Then listen, listen, listen to see if you picked your target well.
All other rules become less true as they become less trivial.
Bricolo,
I'd love to see what you suggest published on this sites wiki. I am reasonable at business modelling - just not good at speaker modelling. (I'm sure I could help someone design some Wiki pages that are practical to all - regardless of experience level, I just lack the knowledge in the DIY realm).
I see so much "in common" posted on this (and other) sites regarding what is deemed "best practice" for DIY.
What happened to the good old FAQ's of usenet? (What's a "usenet" I hear the younger members cry? 🙂
I firmly believe in the 80/20 rule. I believe most people, if they followed some of the common practices / rules in speaker design, would end up in at least an 80% sounding speaker - which would be at least 50% better (bang for buck) over a commercial model.
Ok - off the soap box.... and a totally unrelated reply to your thread 🙂
David.
I'd love to see what you suggest published on this sites wiki. I am reasonable at business modelling - just not good at speaker modelling. (I'm sure I could help someone design some Wiki pages that are practical to all - regardless of experience level, I just lack the knowledge in the DIY realm).
I see so much "in common" posted on this (and other) sites regarding what is deemed "best practice" for DIY.
What happened to the good old FAQ's of usenet? (What's a "usenet" I hear the younger members cry? 🙂
I firmly believe in the 80/20 rule. I believe most people, if they followed some of the common practices / rules in speaker design, would end up in at least an 80% sounding speaker - which would be at least 50% better (bang for buck) over a commercial model.
Ok - off the soap box.... and a totally unrelated reply to your thread 🙂
David.
Skinny,
If you want to get more precise at cone area measurement, try: http://sound.westhost.com/tsp.htm
Although I doubt this would be more than 5% accurate - in fact I've heard people use "generalised" area's for the various 8", 10", 12" etc... driver diameters without any significant effect on large signal response modelling.
Dave.
If you want to get more precise at cone area measurement, try: http://sound.westhost.com/tsp.htm
Although I doubt this would be more than 5% accurate - in fact I've heard people use "generalised" area's for the various 8", 10", 12" etc... driver diameters without any significant effect on large signal response modelling.
Dave.
The thing is, that for the momment I'm asking for some informationDave Bullet said:
But if all my questions are answeared, I'll be glad to write something for this site 🙂
Some tricks taken from http://www.aloha-audio.com
Magical numbers:
1.000 / 1.618 / 2.618 / 4.236 / 6.853
1/1.618 is also the best position for your tweeter (internal position) to avoid standing waves
the second thing from this site:
Lynn Olson tells that placing a woofer and a port as close as possible to the floor, adds some magic to the sound
Magical numbers:
1.000 / 1.618 / 2.618 / 4.236 / 6.853
1/1.618 is also the best position for your tweeter (internal position) to avoid standing waves
the second thing from this site:
Lynn Olson tells that placing a woofer and a port as close as possible to the floor, adds some magic to the sound
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