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Topic with many replies

Create your own festival stereo


Author Message
Written on: 16.06.2011 13:19
Jacob Mortensen
Posts: 14
Saturnus wrote:

Jacob Mortensen wrote:
In my opinion MDF is very good material for sound - it "kills" the sound better inside the cabinet than "krydsfiner :S", (plywood?).


That's actually not a good quality for a reflex build icon_wink.gif



All right icon_smile.gif So you think I should use plywood in the future builds? I am very open for inputs since I am no kind of an expert in this field. My designmethod is something like "trial/error" icon_redface.gif
Written on: 16.06.2011 13:40
Saturnus
Posts: 3047
The difference lies in the inherent adiabatic properties. Plywood tends to be more reflective while MDF tends to be more absorbant of air pressure energy. The only cabinet types that can benefit from an absorbant cabinet is a closed box and a BW4 bandpass cabinet (and only for the closed part of that), all other cabinet types benefit more from a reflective cabinet. This is because in closed box only the driver should reproduce sound, and the object is to transfer all energy inside the box into heat as quickly as possible. In all other cabinet types the cabinet should be as reflective as possible because they work on the principle that there is no internally wasted energy. For example in a reflex cabinet the internal air pressure energy is what excite the volume of air trapped in the port to produce lower notes. The more absorbant the cabinet is the less energy is left for that process, and vice versa for a reflective material.
Written on: 16.06.2011 14:35
Jacob Mortensen
Posts: 14
Nice to get such a theorytical and well described answer - thanks! I will take that in my considerations next time Im stupid enough to spend SU-money on similar projects icon_smile.gif
Written on: 16.06.2011 18:29
Per Andersen
Posts: 15
@ saturnus

I just wondered about where you got all you knowledge from? is it from your education, or just learning by doing?
Written on: 16.06.2011 18:39
Saturnus
Posts: 3047
I have no formal education in the field but you in principle don't need to go to a school to learn such stuff, you can just read (and understand) the books explaining the underlying physics. And do your own research if you are so inclined.

The first starting ground for any would be DIYer with an interest of understanding what actually goes on is naturally to read Vance Dickenson's Loudspeaker Cookbook. After that, and if you don't mind complicated mathematics you should read the works of Dr. Thiele and Professor Small.
Written on: 16.06.2011 18:39
Zaki Souary
Posts: 15
Saturnus wrote:

Zaki Souary wrote:

Does anyone know a shop or place in Copenhagen we can go to and have our system checked out by a pro? We've pretty much given up ourselves. We tried with a thicker line between the amp and the battery, but it didn't work... We're out of good ideas.

Thanks.


If you pay me, I can have a look at it Sunday or Monday.



We'll try with a battery that we know are fully charged, but if that doesn't work, we're in for your deal. Name a price and we're ready.
Written on: 16.06.2011 22:39
Pryning
Posts: 6
Please anyone?
Some device to make my light flash to the music? It would be a really cool addition to our camp.


Pretty please...
Written on: 16.06.2011 22:59
Mikkel S
Posts: 18
Pryning wrote:

Please anyone?
Some device to make my light flash to the music? It would be a really cool addition to our camp.


Pretty please...


You can buy lights with build in mic. They react to the music. They drain a lot of power, though.
Written on: 16.06.2011 23:17
Pryning
Posts: 6
Mikkel S wrote:

Pryning wrote:

Please anyone?
Some device to make my light flash to the music? It would be a really cool addition to our camp.


Pretty please...


You can buy lights with build in mic. They react to the music. They drain a lot of power, though.


yearh i know. I'm just so sure i saw some switch that you ran your input through. But i just cant find it.

[This article was edited 1 times, at last 16.06.2011 at 23:33.]
Written on: 17.06.2011 00:00
ThokN
Posts: 77
Pryning wrote:

Mikkel S wrote:

Pryning wrote:

Please anyone?
Some device to make my light flash to the music? It would be a really cool addition to our camp.


Pretty please...


You can buy lights with build in mic. They react to the music. They drain a lot of power, though.


yearh i know. I'm just so sure i saw some switch that you ran your input through. But i just cant find it.

We use this on a seperate light-system. I don't think it has line in however, only a sensitive mic. No idea of how much power it drains, but it is only 10kr icon_smile.gif
http://www.thansen.dk/product.asp?c=5449550848&n=-1026413937&pn=-1450739965
Written on: 17.06.2011 00:12
Pryning
Posts: 6
ThokN wrote:

Pryning wrote:

Mikkel S wrote:

Pryning wrote:

Please anyone?
Some device to make my light flash to the music? It would be a really cool addition to our camp.


Pretty please...


You can buy lights with build in mic. They react to the music. They drain a lot of power, though.


yearh i know. I'm just so sure i saw some switch that you ran your input through. But i just cant find it.

We use this on a seperate light-system. I don't think it has line in however, only a sensitive mic. No idea of how much power it drains, but it is only 10kr icon_smile.gif
http://www.thansen.dk/product.asp?c=5449550848&n=-1026413937&pn=-1450739965


that looks alright. And as you say it's only 10 kr icon_razz.gif
I'm gonna get that.

But if anyone knows of another one i would like to hear about it.

I will alså see if i can find out how much power it uses, and post it here icon_smile.gif

thx
Written on: 17.06.2011 09:36
Rasmus123
Posts: 108
Saturnus wrote:

The difference lies in the inherent adiabatic properties. Plywood tends to be more reflective while MDF tends to be more absorbant of air pressure energy. The only cabinet types that can benefit from an absorbant cabinet is a closed box and a BW4 bandpass cabinet (and only for the closed part of that), all other cabinet types benefit more from a reflective cabinet. This is because in closed box only the driver should reproduce sound, and the object is to transfer all energy inside the box into heat as quickly as possible. In all other cabinet types the cabinet should be as reflective as possible because they work on the principle that there is no internally wasted energy. For example in a reflex cabinet the internal air pressure energy is what excite the volume of air trapped in the port to produce lower notes. The more absorbant the cabinet is the less energy is left for that process, and vice versa for a reflective material.


But if you build a 18inch subwoofer wont MDF 22mm be better than Plywood ?

http://www.diyaudioandvideo.com/FAQ/Build/

"MDF is a somewhat like particleboard in that it is made up of wood fibers glued together. The difference is the density of the fibers in the wood. Fiberboard is denser, harder, and stiffer over plywood and particleboard. It is a dead wood that won't resonate"

[This article was edited 1 times, at last 17.06.2011 at 09:40.]
Written on: 17.06.2011 10:36
Saturnus
Posts: 3047
Rasmus123 wrote:

Saturnus wrote:

The difference lies in the inherent adiabatic properties. Plywood tends to be more reflective while MDF tends to be more absorbant of air pressure energy. The only cabinet types that can benefit from an absorbant cabinet is a closed box and a BW4 bandpass cabinet (and only for the closed part of that), all other cabinet types benefit more from a reflective cabinet. This is because in closed box only the driver should reproduce sound, and the object is to transfer all energy inside the box into heat as quickly as possible. In all other cabinet types the cabinet should be as reflective as possible because they work on the principle that there is no internally wasted energy. For example in a reflex cabinet the internal air pressure energy is what excite the volume of air trapped in the port to produce lower notes. The more absorbant the cabinet is the less energy is left for that process, and vice versa for a reflective material.


But if you build a 18inch subwoofer wont MDF 22mm be better than Plywood ?

http://www.diyaudioandvideo.com/FAQ/Build/

"MDF is a somewhat like particleboard in that it is made up of wood fibers glued together. The difference is the density of the fibers in the wood. Fiberboard is denser, harder, and stiffer over plywood and particleboard. It is a dead wood that won't resonate"


It's those kinds of generalizations you have to look beyond. High quality plywood is stiffer and harder than MDF, and have exactly the same density. And best of all it's not a dead wood so it will resonate which is a desirable quality as I described above.

I'll reiterate myself, the main reason MDF is used extensively in commercial speaker is not that it's better, it's because it's cheaper. Most quality professional speakers are made of plywood.
Written on: 17.06.2011 10:46
Rasmus123
Posts: 108
Looks like the price are the same as MDF: http://www.ezwoodshop.com/plywood/plywood-prices.html

3/4 Plywood is also 40 dollar.


I think that MDF has a better low tone quality wich is good for deep bass sounds, our system plays perfect with MDF. If you use Plywood i think the sound would reflect and you wont get that deep bass sound.

In our system the sound becomes a part of the box and channels the sounds to the ground, wich is very useful when you want to make a strong bass.

[This article was edited 1 times, at last 17.06.2011 at 10:50.]
Written on: 17.06.2011 11:00
Ruben
Posts: 69
Rasmus123 wrote:

Looks like the price are the same as MDF: http://www.ezwoodshop.com/plywood/plywood-prices.html

3/4 Plywood is also 40 dollar.


I think that MDF has a better low tone quality wich is good for deep bass sounds, our system plays perfect with MDF. If you use Plywood i think the sound would reflect and you wont get that deep bass sound.

In our system the sound becomes a part of the box and channels the sounds to the ground, wich is very useful when you want to make a strong bass.


When you go to a hardware store e.g. Silvan (or any other) plywood will always be more expnsive than MDF in the same thickness. And especially filmed birch plywood is at the top.

For me - the main reason I DON'T want to use MDF for outdoor projects, is the ability for it to fall apart when it gets wet. As you mentioned yourself, MDF is wood particles glued together and moist/rain can dissolve the structure.

What would be more sad than running out of power is to see your stereo, which you have spent a couple of thousands on, go to waste.

[This article was edited 1 times, at last 17.06.2011 at 11:01.]
Written on: 17.06.2011 11:12
Rasmus123
Posts: 108
MDF should be fine if you give it 3 times Oil Paint Outdoor.

I also think that building it in Plywood you will make hollow sound.

The best thing to do would be building the bass in a MDF and the middle tones and horns in Plywood to prevent a heavy lifting.

[This article was edited 1 times, at last 17.06.2011 at 11:40.]
Written on: 17.06.2011 11:45
Saturnus
Posts: 3047
Rasmus123 wrote:

Looks like the price are the same as MDF: http://www.ezwoodshop.com/plywood/plywood-prices.html

3/4 Plywood is also 40 dollar.


None of those plywood are even close to being high enough quality for loudspeakers. For for example 12mm you need at least 7 ply plywood, for 18mm you need at least 11 ply plywood.
Written on: 17.06.2011 11:47
Saturnus
Posts: 3047
Rasmus123 wrote:

MDF should be fine if you give it 3 times Oil Paint Outdoor.

I also think that building it in Plywood you will make hollow sound.

The best thing to do would be building the bass in a MDF and the middle tones and horns in Plywood to prevent a heavy lifting.


No no no. You're not listening to a thing I say, and ignoring all scientific evidence. It's actually vice versa, plywood is best for bass, MDF is acceptable for midrange (if it's a closed box.
Written on: 17.06.2011 12:02
Jim Daggerthuggert
Posts: 600
Rasmus123 is a clever troll, "misunderstanding" every thing. That or a very stupid person. I'm pretty sure it's the first.

Read a couple of his post in diferent topics and see if I'm not right.
Written on: 17.06.2011 12:05
Rasmus123
Posts: 108
I read this: http://www.diyaudioandvideo.com/FAQ/Build/


Jim please stop hunting me, i do not have a bounty!

And now i read this:

http://answers.yahoo.com/question/index?qid=20080531220410AAIX4vP

[This article was edited 1 times, at last 17.06.2011 at 12:07.]
Written on: 17.06.2011 12:08
Saturnus
Posts: 3047
Rasmus123 wrote:

I read this: http://www.diyaudioandvideo.com/FAQ/Build/


Jim please stop hunting me, i do not have a bounty!

And now i read this:

http://answers.yahoo.com/question/index?qid=20080531220410AAIX4vP


http://www.frommyexperience.com/google-confirms-moon-made-of-cheese.php
Written on: 17.06.2011 12:19
Rasmus123
Posts: 108
http://www.youtube.com/watch?v=Im8WhG-8FGw

Written on: 17.06.2011 12:35
Phaedras
Posts: 42
Rasmus123 wrote:


....



Obvious troll is obvious!

Stop posting completely irrelevant stuff and stop trolling icon_smile.gif
Written on: 17.06.2011 12:36
Rasmus123
Posts: 108
Phaedras wrote:

Rasmus123 wrote:


....



Obvious troll is obvious!

Stop posting completely irrelevant stuff and stop trolling icon_smile.gif


Stop hunting trolls. Your obvious a troll hunter.

Go join the army of troll hunters! http://www.youtube.com/watch?v=ydCVAff68oA

[This article was edited 1 times, at last 17.06.2011 at 12:40.]
Written on: 17.06.2011 13:05
Jim Daggerthuggert
Posts: 600
http://i1191.photobucket.com/albums/z479/TrollHunterRF/troll.jpg


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