Yes, many brands sell plastic (wood 'look') for the cheaper cabinets and veneer for the more expensive line...
Check the link about the other PL18 design (the TL) I posted before, the threadstarter posted a picture somewhere made in a freeware design program.. He wrote it worked pretty good...
Check the link about the other PL18 design (the TL) I posted before, the threadstarter posted a picture somewhere made in a freeware design program.. He wrote it worked pretty good...
"I spent some time modeling in sketchup,
which works fairly well for being free"
This is a quote from Nebelk from that other thread...about a PL18 TL
which works fairly well for being free"
This is a quote from Nebelk from that other thread...about a PL18 TL
Ok thanks !
Sketchup seams to be a nice software to design my cabinet in 3D to visualize the size but I also need a good software to assist me in tuning the box to the right frequency, compute port size, cabinet size ...
What do you think is the best: placing the port in front or back of the cabinet ?
Thanks,
REALFLEO
Sketchup seams to be a nice software to design my cabinet in 3D to visualize the size but I also need a good software to assist me in tuning the box to the right frequency, compute port size, cabinet size ...
What do you think is the best: placing the port in front or back of the cabinet ?
Thanks,
REALFLEO
I usually prefer the front...but some say this gives more audible port hiss. The down side of using the rear is that the speaker needs space behind it(to rear wall).
I usually guess my port diameter and experiment with different lengths...larger port gives more output (and more high freqs) and less hiss. smaller dia. gives less output and tunes the curve more deeply.
Longer ports tune the freq. lower and shorter tunes it higher.
Because all this is very room and taste dependent I find this works best (and it appears all my ear-tuned cabinets measure very 'flat' in practise....discovered this lately as one of my collegues has a portable spectrum analizer and measured some of my designs a couple of days ago.. he was quite impressed...) to tune it to your own preference..
Though it's more expensive I like to build proto cabinets from fibreboard or PVC first, this way I get to know the driver better and get much better endresults....I've blown away several commercial loudspeakers (not only my opinion) and modified many of them to large improvements. All I can say is follow your ears and compare compare compare (allways changing one thing at the time)..
Don't give up, you'll get there! Afterall you know what you like, don't you?
P.S. there are several programs that calculate portsize, just google...
I usually guess my port diameter and experiment with different lengths...larger port gives more output (and more high freqs) and less hiss. smaller dia. gives less output and tunes the curve more deeply.
Longer ports tune the freq. lower and shorter tunes it higher.
Because all this is very room and taste dependent I find this works best (and it appears all my ear-tuned cabinets measure very 'flat' in practise....discovered this lately as one of my collegues has a portable spectrum analizer and measured some of my designs a couple of days ago.. he was quite impressed...) to tune it to your own preference..
Though it's more expensive I like to build proto cabinets from fibreboard or PVC first, this way I get to know the driver better and get much better endresults....I've blown away several commercial loudspeakers (not only my opinion) and modified many of them to large improvements. All I can say is follow your ears and compare compare compare (allways changing one thing at the time)..
Don't give up, you'll get there! Afterall you know what you like, don't you?
P.S. there are several programs that calculate portsize, just google...
I have a question about calculating cabinet volume.
Do I have to add volume occupied(internally) by drivers and damping material like foam or bitumen sheets ?
Do you think it could help if I paint the interior of cabinets with a waterproof sealer to seal the MDF + the bitumen sheets ?
I'm designing the cabinet now. Is it possible to build a good cabinet(first time) without having to play with his size for testing
Thanks,
REALFLEO
Do I have to add volume occupied(internally) by drivers and damping material like foam or bitumen sheets ?
Do you think it could help if I paint the interior of cabinets with a waterproof sealer to seal the MDF + the bitumen sheets ?
I'm designing the cabinet now. Is it possible to build a good cabinet(first time) without having to play with his size for testing
Thanks,
REALFLEO
The drivers don't take up much volume, a difference in size like what they take (maybe one liter?) usually doesn't change much to the sound.
As for the interior I think it is most important to eliminate the rear radiated waves (in negative-phase) as effective as possible. I got to work with a foam laminated with bitumen to dampen the inside of a generator room in the back of a journal wagon.. This stuff (don't know the brand at the moment) seemed really suitable to dampen both panel resonances and waves in the cabinet at the same time...
I think this material can be DIY-ed.... better....😉
The outside dimensions and finishing of the cabinet maybe deserve even more attention as it influences the radiation behavior of the frontal (positive phase) radiated waves. (I think you allready know enough about this?)
The cabinet size can be calculated to get good results on average. The proto cabinet will only provide the benefit of tuning it to flavour or room... and the outside dimensions can be thoroughly tested..
My preference is rather open clear sound, many others prefer warm and full sound. Now if you make a slimmer design (maybe tweeter in small cabinet on top) you get more open , some say 'thin' sound. If you make a wider cabinet the sound will become warmer and fuller, but the high freqs. won't spread as widely. You can offcourse combine a wide woofer cabinet with a tweeter on top, if that's your preference (fuller bass-mid)...all this with equal cabinet volume...
Don't worry too much about the cabinet volume, but if you want you can leave a panel unglued so you can shift it in and out to tune the volume. Offcourse glue it when your done... Same goes for the port, just try a couple with different length.. Maybe you don't like the idea of making a proto, but all this experimenting is better done on cheaper material than the final cabinet (and believe me you'll be happier afterwards, I messed up many good constructed cabinets myself in ignorance
)
As for the interior I think it is most important to eliminate the rear radiated waves (in negative-phase) as effective as possible. I got to work with a foam laminated with bitumen to dampen the inside of a generator room in the back of a journal wagon.. This stuff (don't know the brand at the moment) seemed really suitable to dampen both panel resonances and waves in the cabinet at the same time...
I think this material can be DIY-ed.... better....😉
The outside dimensions and finishing of the cabinet maybe deserve even more attention as it influences the radiation behavior of the frontal (positive phase) radiated waves. (I think you allready know enough about this?)
The cabinet size can be calculated to get good results on average. The proto cabinet will only provide the benefit of tuning it to flavour or room... and the outside dimensions can be thoroughly tested..
My preference is rather open clear sound, many others prefer warm and full sound. Now if you make a slimmer design (maybe tweeter in small cabinet on top) you get more open , some say 'thin' sound. If you make a wider cabinet the sound will become warmer and fuller, but the high freqs. won't spread as widely. You can offcourse combine a wide woofer cabinet with a tweeter on top, if that's your preference (fuller bass-mid)...all this with equal cabinet volume...
Don't worry too much about the cabinet volume, but if you want you can leave a panel unglued so you can shift it in and out to tune the volume. Offcourse glue it when your done... Same goes for the port, just try a couple with different length.. Maybe you don't like the idea of making a proto, but all this experimenting is better done on cheaper material than the final cabinet (and believe me you'll be happier afterwards, I messed up many good constructed cabinets myself in ignorance
)but when making a proto there will be a tons of differents parameters like: no rounded edges(diffraction), drivers won't be flush mounted on the baffle, no hardwood cover...
Should I try different damping materials at this point ?
Ok maybe the point is just to have an idea of the sound ...
Thanks,
REALFLEO
Should I try different damping materials at this point ?
Ok maybe the point is just to have an idea of the sound ...
Thanks,
REALFLEO
Yes that's it, the rounded edges and material improve only a few percent of the result. The proto just cancels out mishabs of the larger scale...
And try as much as you like on the proto (damping material if you like, but the difference between a pillow inside or most expensive ultra super foam is mostly only a few percent too, not to be underestimated in the endresult offcourse). I make my proto's only to test volume, shape and driver placement (mostly they look quite hideous 😀 ).
And try as much as you like on the proto (damping material if you like, but the difference between a pillow inside or most expensive ultra super foam is mostly only a few percent too, not to be underestimated in the endresult offcourse). I make my proto's only to test volume, shape and driver placement (mostly they look quite hideous 😀 ).
ok perfect ! I think I'll took time to build a proto, it seams to worth the time investment.
Do I have to build the crossover and install it in the enclosure when testing it ? Do you test your box to have a QL of 7 this way ?
So maybe I should try to design the crossover. Do I need it for the proto ?
Thanks,
REALFLEO
Do I have to build the crossover and install it in the enclosure when testing it ? Do you test your box to have a QL of 7 this way ?
So maybe I should try to design the crossover. Do I need it for the proto ?
Thanks,
REALFLEO
Hi realfleo,
I think it is worth the investment, the experience makes you go a lot faster, more determined and less prone to failure. It won't have to cost much, a lot less than messing up the final cabinet.
Don't build the filter in the cabinet, it is much easier to tweak from the outside, just let the speaker leads come through a hole (with minimal leakage!) or the port...
The room also influences total Q so to get best results in your room tune it to preference. On the other hand if you may want to be able to use them on other locations.
To test the proto well (balance and all...) you need to build some sort of reasonably well functioning filter...
I think it is worth the investment, the experience makes you go a lot faster, more determined and less prone to failure. It won't have to cost much, a lot less than messing up the final cabinet.
Don't build the filter in the cabinet, it is much easier to tweak from the outside, just let the speaker leads come through a hole (with minimal leakage!) or the port...
The room also influences total Q so to get best results in your room tune it to preference. On the other hand if you may want to be able to use them on other locations.
To test the proto well (balance and all...) you need to build some sort of reasonably well functioning filter...
ok perfect !
What kind of bracing should I use:
horizontal bracing like that design:
http://www.solen.ca/domont/premium/prembox.jpg
or vertical bracing:
http://www.partsexpress.com/imageslarge/302-700i.jpg
I want to place the port on the baffle.
Should I use braces in my proto ?
Thanks,
REALFLEO
What kind of bracing should I use:
horizontal bracing like that design:
http://www.solen.ca/domont/premium/prembox.jpg
or vertical bracing:
http://www.partsexpress.com/imageslarge/302-700i.jpg
I want to place the port on the baffle.
Should I use braces in my proto ?
Thanks,
REALFLEO
Just the largest surfaces, with every brace you half the potential resonant wave into one needing far more energy and on a higher freq.
When thick enough material with good enough internal damping is used the resonaces will decrease a lot with just a few braces.
By the way, some companies can measure the specs of your design for just little money. You can even get a simple microphone and use software (cheap or maybe even free) to get an idea of how it measures... I have a fine device for this I bought a few years ago for about 500 EUR. I don't know the latest on this....
You can push a wooden stick between two panels to get an idea in your proto of how bracing would affect it. Afterall you won't play loud levels right away, will you? ("Don't go far over 95 db for the first 100 hours or so!....").
A nice thing to add is when you're quite satisfied with the proto, build the second one for real. You'll be glad you tackled all those problems in the proto, and can do A/B testing with the real one! Most designs I made this way turned out even that littlebit better in the real one...
Don't build till late, get a workshed where you can leave everything behind more or less and sleep over the experiences more often than your urge for "the listen" would normally allow. Sometimes the greatest ideas went through my head thinking over it a night, sometimes I lay in bed bad tripping on the knowledge I should've done this or that, don't let this happen!
Offcourse you know a lot I posted allready, but just don't like it to go wrong....
When thick enough material with good enough internal damping is used the resonaces will decrease a lot with just a few braces.
By the way, some companies can measure the specs of your design for just little money. You can even get a simple microphone and use software (cheap or maybe even free) to get an idea of how it measures... I have a fine device for this I bought a few years ago for about 500 EUR. I don't know the latest on this....
You can push a wooden stick between two panels to get an idea in your proto of how bracing would affect it. Afterall you won't play loud levels right away, will you? ("Don't go far over 95 db for the first 100 hours or so!....").
A nice thing to add is when you're quite satisfied with the proto, build the second one for real. You'll be glad you tackled all those problems in the proto, and can do A/B testing with the real one! Most designs I made this way turned out even that littlebit better in the real one...
Don't build till late, get a workshed where you can leave everything behind more or less and sleep over the experiences more often than your urge for "the listen" would normally allow. Sometimes the greatest ideas went through my head thinking over it a night, sometimes I lay in bed bad tripping on the knowledge I should've done this or that, don't let this happen!
Offcourse you know a lot I posted allready, but just don't like it to go wrong....
Hi,
Yesterday I read a lot about testing loudspeaker and I was wondering if I need to break-in driver and calculate Q, Vas anf fs.
If I have to break-in my driver, can I use WinISD to generate a 25Hz frequence and a normal home theater amp connected to my drivers for 12h ? The book Loudspeaker design cookbook suggest a "25Hz with a normal voltage for 12h", I thought about this solution cuz I don't have a signal generator and voltmeter at home.
I also want to know what kind of test should I perform on my proto. The book I'm reading(loudspeaker design cookbook) talk about testing Ql to be close to Ql=7 but what are the other important criterias to mesure on my proto ?
Thanks,
REALFLEO
Yesterday I read a lot about testing loudspeaker and I was wondering if I need to break-in driver and calculate Q, Vas anf fs.
If I have to break-in my driver, can I use WinISD to generate a 25Hz frequence and a normal home theater amp connected to my drivers for 12h ? The book Loudspeaker design cookbook suggest a "25Hz with a normal voltage for 12h", I thought about this solution cuz I don't have a signal generator and voltmeter at home.
I also want to know what kind of test should I perform on my proto. The book I'm reading(loudspeaker design cookbook) talk about testing Ql to be close to Ql=7 but what are the other important criterias to mesure on my proto ?
Thanks,
REALFLEO
You can use any signal that makes the speaker move, house music for instance. A 25hz sinuswave will not be produced in free air and won't bother you or your neighbours. The moderate voltage can be produced
by an amp...just don't push it too far...
I also play bassheavy music to break it in, only I take longer period than 12 hours (several periods of a couple of hours spread through a couple of days...)
Be carefull with a free-air operated driver, it won't be able to handle great power!
The proto tells you much more by listening than mere measuring would. I for instance made a proto once with the speaker cut-outs in the front and the side, a separate panel was used to cover the cut-outs that weren't 'in use'. This tells a lot about whether making a wide-undeep or narrow-deep cabinet. You can also make two separate panels, one with the speaker cut-outs, you can test whether you want the woofer or tweeter on top....The human ear can judge things that cannot be judged as easy by measuring, good results depend on both offcourse...Ql is dependant on cabinet volume (combined with a given driver..) things like radiation behavior are easier to hear than measure for instance. It's more important to train your own ears and get familiar with the drivers. After this you'll probably think it was easier than you thought (the driver combination for instance is excellent to start with. And these drivers don't need a lot of effort to sound great. They don't need any heavy filtering, and a bassreflex cabinet is fairly easy to tune.
Just 1:create, 2:listen, 3:tweak, 4:listen and THAN 5:measure, go back to 3: and so on......
Larger cabinet: higher Ql, lower roll-off, higher low freq. output, eventually sloppy bass.
Smaller cabinet: lower Ql, higher roll-off, lower low freq. output, tighter bass, good transient response, eventually bass shy.
Read this, especially the part described in post#10 on radiation behavior off-axis and on-axis....
http://www.diyaudio.com/forums/showthread.php?s=&threadid=91218
by an amp...just don't push it too far...
I also play bassheavy music to break it in, only I take longer period than 12 hours (several periods of a couple of hours spread through a couple of days...)
Be carefull with a free-air operated driver, it won't be able to handle great power!
The proto tells you much more by listening than mere measuring would. I for instance made a proto once with the speaker cut-outs in the front and the side, a separate panel was used to cover the cut-outs that weren't 'in use'. This tells a lot about whether making a wide-undeep or narrow-deep cabinet. You can also make two separate panels, one with the speaker cut-outs, you can test whether you want the woofer or tweeter on top....The human ear can judge things that cannot be judged as easy by measuring, good results depend on both offcourse...Ql is dependant on cabinet volume (combined with a given driver..) things like radiation behavior are easier to hear than measure for instance. It's more important to train your own ears and get familiar with the drivers. After this you'll probably think it was easier than you thought (the driver combination for instance is excellent to start with. And these drivers don't need a lot of effort to sound great. They don't need any heavy filtering, and a bassreflex cabinet is fairly easy to tune.
Just 1:create, 2:listen, 3:tweak, 4:listen and THAN 5:measure, go back to 3: and so on......
Larger cabinet: higher Ql, lower roll-off, higher low freq. output, eventually sloppy bass.
Smaller cabinet: lower Ql, higher roll-off, lower low freq. output, tighter bass, good transient response, eventually bass shy.
Read this, especially the part described in post#10 on radiation behavior off-axis and on-axis....
http://www.diyaudio.com/forums/showthread.php?s=&threadid=91218
Thanks a lot for all your detailled anwsers !
What is your opinion about testing drivers. Should I use fabricant specs or mesure it myself ?
Thanks,
REALFLEO
What is your opinion about testing drivers. Should I use fabricant specs or mesure it myself ?
Thanks,
REALFLEO
v-bro said:
All this on same driver offcourse....
The complexity of creating a design is in discovering the ways to balance the freq. response, for instance a larger cabinet works on the under 150 hz part of the curve. A wider cabinet works more on freqs above this, though in a negative way above the midrange part of the curve... Radiation behavior of the high freqs depends much on a small and rounded enclosure, low freqs spread around fairly easy anyway. This can help keeping the balance on very high angle off-axis..
The simplicity is in understanding this well and after vast listening experience you'll find the point where you don't want to change anything anymore, or at least you'll know better what part causes what needs to be changed. And eventually most loudspeakers seem to keep sounding better over time due to breaking in....
The given manufacturers thiele and small parameters should match quite well with reality, the frequency response (and with some other brands also the power handling) mostly don't look just as nice when measured by yourself. Measuring the freq response can be done in many ways to make it look nicer, mic. distance, dead or semi dead room, sometimes even the scaling or layout are misleading...
Also impedance is just the 'on average' value, distortion is mostly not given by manufacturers, most of them don't show off-axis response etc.etc.
The brands you use though have quite a good reputation on being
quite honestly presented.... 😉
Here's a nice link to a thread where boundary effects are shown quite nicely:http://www.htguide.com/forum/showthread.php4?t=13689
That's what a room can do!
So that's why some designs need to be disigned to adapt to the room in the best way...I have a very asymmetric room that allows me to place pretty high Ql speakers without becoming too 'boomy'. Some rooms have such bass amplification properties that smaller enclosure (low Ql) would be preferred....
Offcourse the amplification should be judged from the listening position...
Many equal drivers are placed in different size enclosures in different designs by the way... That's what I mean by saying it's just a matter of preference. Bass reflex at least allows you to tune the bassport to preference..I've seen commercial designs in the past that were even supplied with different ports in various length, advertised to let you tune it to your room.....
That's what a room can do!
So that's why some designs need to be disigned to adapt to the room in the best way...I have a very asymmetric room that allows me to place pretty high Ql speakers without becoming too 'boomy'. Some rooms have such bass amplification properties that smaller enclosure (low Ql) would be preferred....
Offcourse the amplification should be judged from the listening position...
Many equal drivers are placed in different size enclosures in different designs by the way... That's what I mean by saying it's just a matter of preference. Bass reflex at least allows you to tune the bassport to preference..I've seen commercial designs in the past that were even supplied with different ports in various length, advertised to let you tune it to your room.....
interresting ...
In the book Loudspeaker design cookbook, the author is saying to over-volume the box and ajust the volume with a removable solid filler. What kind of stuff should I use ?
From the same book
Do have a idea how to include them in the Qts ?
Thanks,
REALFLEO
In the book Loudspeaker design cookbook, the author is saying to over-volume the box and ajust the volume with a removable solid filler. What kind of stuff should I use ?
From the same book
Do have a idea how to include them in the Qts ?
Thanks,
REALFLEO
A solid filler can be bricks inside the proto...
Qes only includes Rs from the driver, because any series resistance influences total Q it can be wise to keep this in mind. Or even try and re-calculate Qes and after this calculate Qts again (from new Qes and given Qms together).
I don't calculate much on this, I make sure my cables and (if I even use) coils have very low resistance. Low freq. lowpass filters need very high coil value and have inherent high resistance (becasue the long wire needed). Therefore I use PLLXO filters on the lower freqs. (high value filter components have exaggerated down-sides to them, especially coils) Don't be fooled by using coils with a core in a two way, your midrange will suffer from this, air coils are always preferred in normal passive filters. I warn for this because the low resistance value makes these coils look like good quality, they're not...
Preferrably use thick wire (low resistance) air coils (no core...)
Qes only includes Rs from the driver, because any series resistance influences total Q it can be wise to keep this in mind. Or even try and re-calculate Qes and after this calculate Qts again (from new Qes and given Qms together).
I don't calculate much on this, I make sure my cables and (if I even use) coils have very low resistance. Low freq. lowpass filters need very high coil value and have inherent high resistance (becasue the long wire needed). Therefore I use PLLXO filters on the lower freqs. (high value filter components have exaggerated down-sides to them, especially coils) Don't be fooled by using coils with a core in a two way, your midrange will suffer from this, air coils are always preferred in normal passive filters. I warn for this because the low resistance value makes these coils look like good quality, they're not...
Preferrably use thick wire (low resistance) air coils (no core...)
I mesured Thiele/Small parameters last weekend with the voltage divider technique and I experienced some differences. Fs are close to Vifa's specs but not Qts.
Vifa
Fs:39Hz
Qts:0.35
Mesured
Fs:39.5Hz and 40.5Hz
Qts:0.40 and 0.44
What should I do, use an average of mesured Qts, average of all Qts(including Vifa's Qts) ? I guess I'm building 2 cabinet of the same size ?
I know I already asked you if I need to include other series resistance in my calculation of Qts but I read a technique that suggest to calculate the resistance of the crossover circuit and the resistance of the amp. What do you think about that ?
Thanks,
REALFLEO
Vifa
Fs:39Hz
Qts:0.35
Mesured
Fs:39.5Hz and 40.5Hz
Qts:0.40 and 0.44
What should I do, use an average of mesured Qts, average of all Qts(including Vifa's Qts) ? I guess I'm building 2 cabinet of the same size ?
I know I already asked you if I need to include other series resistance in my calculation of Qts but I read a technique that suggest to calculate the resistance of the crossover circuit and the resistance of the amp. What do you think about that ?
Thanks,
REALFLEO
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