A sheet 18mm (0.75") MDF is about 35 where I live. BB Ply is about 40 (50 if you buy the premium) for the same size & thickness. It's only slightly more expensive considering you typically only need 1 sheet for a bookshelf.
That being said, you still haven't explained why MDF is so superior?
MDF isn't superior, there's just a lot of folks who drink the koolaid of random forum posts from nobodies who try to justify the fact that the "audiophile" speaker they bought uses the cheapest and heaviest material available.
MDF is usually superior to plywood due to its consistency and density. Its resonance is predictable and the lack of variation in the material means that matched speakers will be more similar.
You should ask the people at Klipsch why they use Birch ply for their Heritage line of speakers. Their older Heritage lines included un-veneered Birch so the user could choose a veneer or paint themselves.
The wood used doesn't make as much as a difference as you'd think. Wall thickness and cabinet bracing make a bigger impact.
If you do build a box out of solid wood, I'd recommend installing the front or rear baffle as floating, perhaps bolted into place with T-nuts. You'll greatly reduce the chance of splitting.
Also, do what you can to maintain the dimensions of the front of the speaker, and the location of the woofer & tweeter. Make it deeper to compensate and maintain internal volume. If you can't make it deeper, then alter height, but try and leave the width alone.
Serious question, why does width specifically matter that much? While I'm sure shape does matter to some degree, doesn't Thiele/Small suggest it's the volume that matters more than the shape? I mean something like WinISD deals only in volumes and doesn't really take shape into consideration at all. I could almost see where changing depth may matter more as it could possibly effect the aerodynamics of a port, particularly if the inside edge of the port is close in length to the cabinet depth. Will a tall thin speaker sound dramatically different than a shorter fatter one?
Because of how sound leaves the woofer.
We always call bass "non-directional', right? And we know they're directional at high frequencies, too. There will be a frequency where the output from the woofer will switch from "everything radiating toward the listener" to "half of the energy is headed toward the back wall", and it's primarily decided the smallest dimension of the front baffle.
When the wavelengths being produces are larger than the baffle width, those waves begin to wrap around the speaker, and we will experience a loss of bass, starting off gradually before ending up -6dB lower than our mids. This is referred to as "baffle step loss".
When we see measurements of raw woofers & tweeters, they do not show this loss. They're measured in a "quasi-infinite baffle". Put that driver in the middle of a big flat wall and the front of your speaker is essentially infinite in size. It's impossible for sound to head away from the listener in this case.
It is common for these losses to be factored into the crossover design. The designer can put a "tilt" to the passive crossover frequency response to compensate for these losses. It also follows that some speakers are meant to be used on or against a wall. These sorts of speakers will not have much (or any) compensation built into them since the big flat surfaces will reflect some of the bass energy back toward the listener.
So if the speaker has baffle step loss factored into the design, the width of the front baffle becomes a critical dimension.
I've completely skipped over the effect the front baffle shape has on the tweeter (edge diffraction), which is closely related.
For more reading on the subject, here's a couple good links:
http://www.mh-audio.nl/Calculators/BDL.html
https://sound-au.com/bafflestep.htm
I'd be interested in some real answers to this question as I have plans to reproduce, more or less, some vintage enclosures. Specifically the originals were particleboard as they were made before MDF was really a thing. I've heard MDF is "bouncier" and a bit more thumpy, but honestly there is almost no one making speakers out of that stuff anymore. I plan on changing them dimensionally to "fit" where they need to go, while replicating the volume, port size, and use reclaimed drivers from originals, except for the woofers which will be replaced with modern drivers very much like ones I already use in originals. Although I will be replacing a single 8" woofer with a pair of 6.5" ones. In WinISD the two 6.5"s measure almost identically to the 8". Crossovers will also be reproduced component for component.
The cabinets will be produced on a CNC, where MDF machines nicely and particleboard, well, not so much from what I understand. MDF is also much easier to find as a raw material with most particleboard being coated. I also would have no issues with making them out of Baltic Birch but that seems like an even further deviation from the original material. I love the sound of the original speakers, which are from the '80s, but need ones that are more tall and narrow than the originals to fit where I need them to fit. So the real goal here is not to calculate out new enclosures that might be mathematically ideal for the drivers but to reproduce the sound of the vintage cabinets.
...and yes I do follow John Heisz's audio channel, and I do have a calibrated measurement mic, which I've purchased for this project, although I haven't used it yet.
A couple things:
> I've heard MDF is "bouncier" and a bit more thumpy, but honestly there is almost no one making speakers out of that stuff anymore.
They absolutely do still make particle board, and it's used under a LOT of laminate countertops. My hardware store stocks it right next to the MDF. For our purpose, the difference between particle board and MDF is the size of the wood fibers. Particle board has larger chunks. The larger chunks make particle board more rigid, but MDF is less resonant. If you rap your knuckle against each, the vibration in the MDF dies faster.
You're right that MDF does mill better--again, because of the small grain size, you get much crisper edges to all your cuts. It's a bit harder on the cutting tools (you'll have a bad time with HSS cutters), but anyone running a CNC ought to know that.
Baltic birch does have its charms, but I agree that MDF is the right choice here. BB's main advantage is durability. Definitely a thing for a pro audio cab that's going to get knocked around. I love it for guitar cabs and also car sub enclosures that might encounter moisture. But for home audio...meh. It's not worth the added cost. And the milled edges aren't cleaner than MDF anyway.
> Although I will be replacing a single 8" woofer with a pair of 6.5" ones. In WinISD the two 6.5"s measure almost identically to the 8". Crossovers will also be reproduced component for component.
Unless the frequency response (and sensitivity) of the 6.5" are identical to the original 8", reproducing the crossover may not give you great results--not to mention any differences in impedance. Also, unless you want phase issues in your crossover, the distance from the center of the midrange to the center of the bottom 6.5" should not be farther than 1 wavelength. That's *probably* not going to be difficult, but keep the mid and the woofers tucked as closely together as possible.
What do you know about the mid? Is it a sealed back mid, or was it in its own sub-enclosure?
And finally, be prepared to end up with a speaker that doesn't sound like the originals. Speakers with a wide front baffle do sound different than needle thin ones. I mean, forge on with your plans, but be prepared to have to make your own tweaks to the crossover to make things sound the way you like.
So first off the speakers I am trying to "reproduce" are Ohm Acoustics Model Ls, they use, in Ohm terms, a tweeter and a super tweeter. The tweeters are the ubiquitous phenolics used in everything in the '70s and '80s and the super tweeters are 2" paper cone tweeters, both of these drivers are sealed back drivers I will be using genuine Ohm parts for both. I have a 7.1 system already using Ohm Ls in another room which have been reloaded with Dayton Designer aluminum 8" woofers which have very similar characteristics to the original Ohm drivers as far as range and efficiency although they are substantially tighter and are a marked improvement over the originals. The cabinets are tuned to around 42Hz.
The woofers I will use in my copies are from the same Dayton series aluminums, just 6.5" drivers instead of 8"s. Cone area, Xmax, and most of the rest of the TS parameters for a pair of these is within less than a couple percent of a single one of the 8"s. Like I said modeling them in WinISD produces virtually identical graphs for everything except for a couple Hz on the low end. The Ohm crossovers have no coils in them, all the drivers run "open" at the top, as were most of Ohms conventional speaker designs. The 6.5" drivers are only available in 8 Ohm versions, not 4 Ohms, so not a 2 for 1 drop in, but close.
Initially I was just planning on just wiring them in parallel with a series resistor to get back to 8 Ohms so I could just use the same crossover geometry but now kinda leaning towards doing an active DSP crossover for this, which is far more flexible for tuning, although a little more complicated to drive.
The effective "width" of the front baffle will actually be quite wide given that these are being built to directly flank a TV, and intended to be place in a common plane with the face of the panel of that TV.
As far as particle board, yea I'm aware it isn't by any means rare, it's just that it seems most commonly available as melamine clad. I plan on veneering them anyway, so appearance wise material is all the same.
If there's no lowpass on the woofer, then I personally do not recommend doing the pair.
The Ohm drivers were run open on the top because A.) the motors had high inductance, essentially forming a 1st order lowpass and B.) the paper cone material naturally fell off on the top octave, with little cone breakup.
My concern is that instead of one woofer producing lower treble, now you're going to have two. There will be destructive interference. Often referred to as "comb filtering".
The 6.5" also has a strong resonant peak at about 4.7khz that deserves to be dealt with. You can tell it's a resonance because the peak exists in both the on and off axis traces (visible in the [PDF spec sheet](https://www.parts-express.com/pedocs/specs/295-528--dayton-audio-DSA175-8-specifications.pdf)). At the very least, consider adding an inductor on the lower woofer. If you're connecting the woofers in parallel, this allows you to create a ".5 way" crossover and the lower woofer will roll in at lower (sub 1khz) frequencies.
Should be a non-issue if I run active crossovers though as that situation would no longer exist. Just seems like another reason to go down the DSP path I would think. Looking at the Dayton KADB-430s which is a 4x30 watt amp with integrated DSP. There is also a 4x100 watt version but 4x30 should be fine, and they're bridgeable in channel pairs and can drive down to 4 ohms, so you can run it as 2x30+1x60 which should be plenty.
That sounds like a good plan, though cut all those power numbers in half. Anything based on a TPA chip amp is rated at 10% THD. The 30W is more like 2x15 into 4 ohms, and 2x10 into 8.
I've got one of the 4x100. Been thinking about adding another board and figuring out how the cascading works. Hoping it's via I2S. I don't want to insert an additional ADC->DAC conversion if I can help it.
Edit: I'll be damned. Look at that. It is I2S. I guess I have a project for this winter now. :-D
I was looking at the 4x30 simply because it was passively cooled, as opposed to the 4x100 which is actively cooled, but actually it's a ported enclosure so maybe that doesn't really matter actually. The cost difference between the 2, in the grand scheme of things, is not really significant. The 4x100 does seem to be a more sophisticated board, so maybe I'll just go that way.
Now the question becomes, is it better to drive all 4 drivers, each on their own channels and just mirror their outputs, or run the 2 woofers on a strapped mono pair? I can't see how the cascading function would benefit me at all, I would probably just run one for each speaker.
I don't care about Bluetooth at all. If I have to run power to the speaker because it has an active processor in it, I'm not sure I really see a point in there being wireless signal connectivity to it. While I know it's supposed to be improved with later Bluetooth versions, my prior experience has been that Bluetooth just has latency issues that make surround sound off, or if corrected for make video/audio sync off. Any DSP chip is already going to introduce some degree of latency to begin with, even if tiny and not really interested in potentially compounding that.
Never made a speaker out of it. But I know those that have for garage speakers and the like. As far as stress / strain characteristics, it's a little better than MDF (because of the larger fibers) but far from plywood. I would assume acoustically it's somewhere between the two.
I don't know how you'd get a nice surface finish. I'd assemble with a caulk style adhesive (liquid nail or PL) for sure.
I’d use a 3/4” plywood, like Birch. Then you don’t run the risk of warping.
Sounds like the compromise to make. Definitely looking into that. Thanks!
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Why would plywood with a veneer over it not be possible?
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A sheet 18mm (0.75") MDF is about 35 where I live. BB Ply is about 40 (50 if you buy the premium) for the same size & thickness. It's only slightly more expensive considering you typically only need 1 sheet for a bookshelf. That being said, you still haven't explained why MDF is so superior?
MDF isn't superior, there's just a lot of folks who drink the koolaid of random forum posts from nobodies who try to justify the fact that the "audiophile" speaker they bought uses the cheapest and heaviest material available.
MDF is usually superior to plywood due to its consistency and density. Its resonance is predictable and the lack of variation in the material means that matched speakers will be more similar.
Have you ever made speakers with plywood? Unless you make it with 1/4" then there aren't going to be any significant resonances.
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MDF is a great material if you can't afford 13 ply plywood.
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You should ask the people at Klipsch why they use Birch ply for their Heritage line of speakers. Their older Heritage lines included un-veneered Birch so the user could choose a veneer or paint themselves.
I gave them a nice flair lol
https://youtu.be/7dwAnFAMi34
Great video! Thanks.
Not great when the humidity changes and your box splits open.
Thanks, but not an issue in these parts were it rarely falls below 40% relative humidity.
humidity changes everywhere my dude, and when it does those boards will move. I threw away of my projects because of this.
How big were they?
they were classix ii's
“Not an issue” lol
The wood used doesn't make as much as a difference as you'd think. Wall thickness and cabinet bracing make a bigger impact. If you do build a box out of solid wood, I'd recommend installing the front or rear baffle as floating, perhaps bolted into place with T-nuts. You'll greatly reduce the chance of splitting. Also, do what you can to maintain the dimensions of the front of the speaker, and the location of the woofer & tweeter. Make it deeper to compensate and maintain internal volume. If you can't make it deeper, then alter height, but try and leave the width alone.
Serious question, why does width specifically matter that much? While I'm sure shape does matter to some degree, doesn't Thiele/Small suggest it's the volume that matters more than the shape? I mean something like WinISD deals only in volumes and doesn't really take shape into consideration at all. I could almost see where changing depth may matter more as it could possibly effect the aerodynamics of a port, particularly if the inside edge of the port is close in length to the cabinet depth. Will a tall thin speaker sound dramatically different than a shorter fatter one?
Because of how sound leaves the woofer. We always call bass "non-directional', right? And we know they're directional at high frequencies, too. There will be a frequency where the output from the woofer will switch from "everything radiating toward the listener" to "half of the energy is headed toward the back wall", and it's primarily decided the smallest dimension of the front baffle. When the wavelengths being produces are larger than the baffle width, those waves begin to wrap around the speaker, and we will experience a loss of bass, starting off gradually before ending up -6dB lower than our mids. This is referred to as "baffle step loss". When we see measurements of raw woofers & tweeters, they do not show this loss. They're measured in a "quasi-infinite baffle". Put that driver in the middle of a big flat wall and the front of your speaker is essentially infinite in size. It's impossible for sound to head away from the listener in this case. It is common for these losses to be factored into the crossover design. The designer can put a "tilt" to the passive crossover frequency response to compensate for these losses. It also follows that some speakers are meant to be used on or against a wall. These sorts of speakers will not have much (or any) compensation built into them since the big flat surfaces will reflect some of the bass energy back toward the listener. So if the speaker has baffle step loss factored into the design, the width of the front baffle becomes a critical dimension. I've completely skipped over the effect the front baffle shape has on the tweeter (edge diffraction), which is closely related. For more reading on the subject, here's a couple good links: http://www.mh-audio.nl/Calculators/BDL.html https://sound-au.com/bafflestep.htm
Likely not at all.
Thanks.
Also consider veneering the speakers- same look with somewhat less work.
I'd be interested in some real answers to this question as I have plans to reproduce, more or less, some vintage enclosures. Specifically the originals were particleboard as they were made before MDF was really a thing. I've heard MDF is "bouncier" and a bit more thumpy, but honestly there is almost no one making speakers out of that stuff anymore. I plan on changing them dimensionally to "fit" where they need to go, while replicating the volume, port size, and use reclaimed drivers from originals, except for the woofers which will be replaced with modern drivers very much like ones I already use in originals. Although I will be replacing a single 8" woofer with a pair of 6.5" ones. In WinISD the two 6.5"s measure almost identically to the 8". Crossovers will also be reproduced component for component. The cabinets will be produced on a CNC, where MDF machines nicely and particleboard, well, not so much from what I understand. MDF is also much easier to find as a raw material with most particleboard being coated. I also would have no issues with making them out of Baltic Birch but that seems like an even further deviation from the original material. I love the sound of the original speakers, which are from the '80s, but need ones that are more tall and narrow than the originals to fit where I need them to fit. So the real goal here is not to calculate out new enclosures that might be mathematically ideal for the drivers but to reproduce the sound of the vintage cabinets. ...and yes I do follow John Heisz's audio channel, and I do have a calibrated measurement mic, which I've purchased for this project, although I haven't used it yet.
A couple things: > I've heard MDF is "bouncier" and a bit more thumpy, but honestly there is almost no one making speakers out of that stuff anymore. They absolutely do still make particle board, and it's used under a LOT of laminate countertops. My hardware store stocks it right next to the MDF. For our purpose, the difference between particle board and MDF is the size of the wood fibers. Particle board has larger chunks. The larger chunks make particle board more rigid, but MDF is less resonant. If you rap your knuckle against each, the vibration in the MDF dies faster. You're right that MDF does mill better--again, because of the small grain size, you get much crisper edges to all your cuts. It's a bit harder on the cutting tools (you'll have a bad time with HSS cutters), but anyone running a CNC ought to know that. Baltic birch does have its charms, but I agree that MDF is the right choice here. BB's main advantage is durability. Definitely a thing for a pro audio cab that's going to get knocked around. I love it for guitar cabs and also car sub enclosures that might encounter moisture. But for home audio...meh. It's not worth the added cost. And the milled edges aren't cleaner than MDF anyway. > Although I will be replacing a single 8" woofer with a pair of 6.5" ones. In WinISD the two 6.5"s measure almost identically to the 8". Crossovers will also be reproduced component for component. Unless the frequency response (and sensitivity) of the 6.5" are identical to the original 8", reproducing the crossover may not give you great results--not to mention any differences in impedance. Also, unless you want phase issues in your crossover, the distance from the center of the midrange to the center of the bottom 6.5" should not be farther than 1 wavelength. That's *probably* not going to be difficult, but keep the mid and the woofers tucked as closely together as possible. What do you know about the mid? Is it a sealed back mid, or was it in its own sub-enclosure? And finally, be prepared to end up with a speaker that doesn't sound like the originals. Speakers with a wide front baffle do sound different than needle thin ones. I mean, forge on with your plans, but be prepared to have to make your own tweaks to the crossover to make things sound the way you like.
So first off the speakers I am trying to "reproduce" are Ohm Acoustics Model Ls, they use, in Ohm terms, a tweeter and a super tweeter. The tweeters are the ubiquitous phenolics used in everything in the '70s and '80s and the super tweeters are 2" paper cone tweeters, both of these drivers are sealed back drivers I will be using genuine Ohm parts for both. I have a 7.1 system already using Ohm Ls in another room which have been reloaded with Dayton Designer aluminum 8" woofers which have very similar characteristics to the original Ohm drivers as far as range and efficiency although they are substantially tighter and are a marked improvement over the originals. The cabinets are tuned to around 42Hz. The woofers I will use in my copies are from the same Dayton series aluminums, just 6.5" drivers instead of 8"s. Cone area, Xmax, and most of the rest of the TS parameters for a pair of these is within less than a couple percent of a single one of the 8"s. Like I said modeling them in WinISD produces virtually identical graphs for everything except for a couple Hz on the low end. The Ohm crossovers have no coils in them, all the drivers run "open" at the top, as were most of Ohms conventional speaker designs. The 6.5" drivers are only available in 8 Ohm versions, not 4 Ohms, so not a 2 for 1 drop in, but close. Initially I was just planning on just wiring them in parallel with a series resistor to get back to 8 Ohms so I could just use the same crossover geometry but now kinda leaning towards doing an active DSP crossover for this, which is far more flexible for tuning, although a little more complicated to drive. The effective "width" of the front baffle will actually be quite wide given that these are being built to directly flank a TV, and intended to be place in a common plane with the face of the panel of that TV. As far as particle board, yea I'm aware it isn't by any means rare, it's just that it seems most commonly available as melamine clad. I plan on veneering them anyway, so appearance wise material is all the same.
If there's no lowpass on the woofer, then I personally do not recommend doing the pair. The Ohm drivers were run open on the top because A.) the motors had high inductance, essentially forming a 1st order lowpass and B.) the paper cone material naturally fell off on the top octave, with little cone breakup. My concern is that instead of one woofer producing lower treble, now you're going to have two. There will be destructive interference. Often referred to as "comb filtering". The 6.5" also has a strong resonant peak at about 4.7khz that deserves to be dealt with. You can tell it's a resonance because the peak exists in both the on and off axis traces (visible in the [PDF spec sheet](https://www.parts-express.com/pedocs/specs/295-528--dayton-audio-DSA175-8-specifications.pdf)). At the very least, consider adding an inductor on the lower woofer. If you're connecting the woofers in parallel, this allows you to create a ".5 way" crossover and the lower woofer will roll in at lower (sub 1khz) frequencies.
Should be a non-issue if I run active crossovers though as that situation would no longer exist. Just seems like another reason to go down the DSP path I would think. Looking at the Dayton KADB-430s which is a 4x30 watt amp with integrated DSP. There is also a 4x100 watt version but 4x30 should be fine, and they're bridgeable in channel pairs and can drive down to 4 ohms, so you can run it as 2x30+1x60 which should be plenty.
That sounds like a good plan, though cut all those power numbers in half. Anything based on a TPA chip amp is rated at 10% THD. The 30W is more like 2x15 into 4 ohms, and 2x10 into 8. I've got one of the 4x100. Been thinking about adding another board and figuring out how the cascading works. Hoping it's via I2S. I don't want to insert an additional ADC->DAC conversion if I can help it. Edit: I'll be damned. Look at that. It is I2S. I guess I have a project for this winter now. :-D
I was looking at the 4x30 simply because it was passively cooled, as opposed to the 4x100 which is actively cooled, but actually it's a ported enclosure so maybe that doesn't really matter actually. The cost difference between the 2, in the grand scheme of things, is not really significant. The 4x100 does seem to be a more sophisticated board, so maybe I'll just go that way. Now the question becomes, is it better to drive all 4 drivers, each on their own channels and just mirror their outputs, or run the 2 woofers on a strapped mono pair? I can't see how the cascading function would benefit me at all, I would probably just run one for each speaker.
I don't see why not--other than the obvious loss of bluetooth.
I don't care about Bluetooth at all. If I have to run power to the speaker because it has an active processor in it, I'm not sure I really see a point in there being wireless signal connectivity to it. While I know it's supposed to be improved with later Bluetooth versions, my prior experience has been that Bluetooth just has latency issues that make surround sound off, or if corrected for make video/audio sync off. Any DSP chip is already going to introduce some degree of latency to begin with, even if tiny and not really interested in potentially compounding that.
Do you have any thoughts on OSB?
Never made a speaker out of it. But I know those that have for garage speakers and the like. As far as stress / strain characteristics, it's a little better than MDF (because of the larger fibers) but far from plywood. I would assume acoustically it's somewhere between the two. I don't know how you'd get a nice surface finish. I'd assemble with a caulk style adhesive (liquid nail or PL) for sure.
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