I am about to embark on Dick Olsher's "Basszilla" design, which uses a 15" woofer in a bass cabinet, with a seperate Fostex 8" driver in an open baffle unit on top of the bass cabinet.
I had been suggested that Marine Plywood would be far superior sound-wise to MDF, but my cabinetmaker says there is not much he can do to enhance the final appearance by rounding edges, etc, using the Plywood, as routing will 'eat' into the underlayers and different grain (I was planning to have the cabinets stained in a walnut color).
However, MDF he says is no problem, and this can be easily routed and finished, plus is about a fifth of the cost the Plywood.
Any suggestions as whether the marine plywood is the better option, even if it will look very 'boxy' and have sharp edging all over? This thing is going to end up BIG and HEAVY, so the edges have me worried!
OR, is the likely difference between MDF and marine plywood not that great sound-wise as I may have been led to believe? I have read that most commercial speakers use MDF....I will use 1 inch for whatever I end up using.
Thanks for any feedback/comments!!
I had been suggested that Marine Plywood would be far superior sound-wise to MDF, but my cabinetmaker says there is not much he can do to enhance the final appearance by rounding edges, etc, using the Plywood, as routing will 'eat' into the underlayers and different grain (I was planning to have the cabinets stained in a walnut color).
However, MDF he says is no problem, and this can be easily routed and finished, plus is about a fifth of the cost the Plywood.
Any suggestions as whether the marine plywood is the better option, even if it will look very 'boxy' and have sharp edging all over? This thing is going to end up BIG and HEAVY, so the edges have me worried!
OR, is the likely difference between MDF and marine plywood not that great sound-wise as I may have been led to believe? I have read that most commercial speakers use MDF....I will use 1 inch for whatever I end up using.
Thanks for any feedback/comments!!
My priorities lie in the best sound.....so maybe the sharp edges and the marine ply are my best bet?
My 'craftsman' is not an audio person, and doesnt know anything much about acoustical qualities, etc.
Maybe I could go the marine ply and have the edges notched out, and quarter rounds inserted? If it were stained, then it would show different grains/colors but might still be aesthetically better than the sharp edges.....
My 'craftsman' is not an audio person, and doesnt know anything much about acoustical qualities, etc.
Maybe I could go the marine ply and have the edges notched out, and quarter rounds inserted? If it were stained, then it would show different grains/colors but might still be aesthetically better than the sharp edges.....
Dick doesn't seem to be too concerned since his is all sharp edges IIRC. Anyway, sharp edges are only an audible concern WRT standing waves across the baffle, so if the dims are short WRT the driver's BW then they can't develop. To have a useful radius for long WLs requires that the driver be mounted in a sphere. For instance, a 1" radius round over only affects the BW > ~2158Hz and I imagine my then the mids/HF driver is beaming, and for sure the LF driver is, so it boils down to how much you want to spend on cosmetics.......
GM
GM
Yeah, the bass cabinet would require a very large radius
to be effective, a one inch radius is just decoration.
Which leaves the baffle. The FE208 protrudes out from the baffle considerably and has a raised ridge around it's circumference, so I wonder if the baffle is affecting things that much.
I made my bass box out of ply, but probably a softer wood than the marine ply (there are various types of marine ply I believe also. Made it with 2, 3/4" layers. That sucker is solid but sure eats into the internal volume.
From my boating experience, I believe that marine is void free
and of course water proof glue. There are other premium dense plywoods such a premium birch and what we call appleply in the US that aren't overly waterproof but are void free and possibly denser. and/ or cheaper.
The trendy thing these days seems to be ply. AND for a bass box you are more concerned about stiffness (which I think plywood excels at) rather than damping which is what MDF does well.
Someday I will veneer the whole thing in some fancy veneer
which will look better than almost any plywood. Square corners make veneering pretty easy compared to rounded. So I suggest the ply, with square corners, WHICH WILL weigh about half what an MDF box would!! If you end up loving the Basszilla , then invest in that fancy veneeer later.
I think the bass in plywood and the baffle in MDF is probably the best which is why I do it that way.
I mailed the new design baffles to Dick yesterday so he can begin
developing the new Basszilla based on the Fe208ESigma and the FT 17 tweeter. He said it will be a while so I think proceeding with your existing driver is a good idea.
I have not faceted the new bafffles, they are just flat slabs, in order to eliminate some variables. As in my previous baffles, the tweeter is under, on a vertical baffle and the 208 is in a tilting upper baffle.
Dick has the new drivers in hand, but who knows, maybe he'll hate them!!
Any decision on your bass driver?
to be effective, a one inch radius is just decoration.
Which leaves the baffle. The FE208 protrudes out from the baffle considerably and has a raised ridge around it's circumference, so I wonder if the baffle is affecting things that much.
I made my bass box out of ply, but probably a softer wood than the marine ply (there are various types of marine ply I believe also. Made it with 2, 3/4" layers. That sucker is solid but sure eats into the internal volume.
From my boating experience, I believe that marine is void free
and of course water proof glue. There are other premium dense plywoods such a premium birch and what we call appleply in the US that aren't overly waterproof but are void free and possibly denser. and/ or cheaper.
The trendy thing these days seems to be ply. AND for a bass box you are more concerned about stiffness (which I think plywood excels at) rather than damping which is what MDF does well.
Someday I will veneer the whole thing in some fancy veneer
which will look better than almost any plywood. Square corners make veneering pretty easy compared to rounded. So I suggest the ply, with square corners, WHICH WILL weigh about half what an MDF box would!! If you end up loving the Basszilla , then invest in that fancy veneeer later.
I think the bass in plywood and the baffle in MDF is probably the best which is why I do it that way.
I mailed the new design baffles to Dick yesterday so he can begin
developing the new Basszilla based on the Fe208ESigma and the FT 17 tweeter. He said it will be a while so I think proceeding with your existing driver is a good idea.
I have not faceted the new bafffles, they are just flat slabs, in order to eliminate some variables. As in my previous baffles, the tweeter is under, on a vertical baffle and the 208 is in a tilting upper baffle.
Dick has the new drivers in hand, but who knows, maybe he'll hate them!!
Any decision on your bass driver?
Variac,
I ended up getting the Audax PR380's from Madisound, plus their
Basszilla crossovers too.
All set to go at last, am a bit worried about their size and weight, but am sure this will not be a concern once i get to listen to them!
Will go with the marine ply and have the edges rounded off..might look OK after staining or painting, plus soften their appearance a little.
Mark.
I ended up getting the Audax PR380's from Madisound, plus their
Basszilla crossovers too.
All set to go at last, am a bit worried about their size and weight, but am sure this will not be a concern once i get to listen to them!
Will go with the marine ply and have the edges rounded off..might look OK after staining or painting, plus soften their appearance a little.
Mark.
Well, As you know from my longwinded comments, 
everyone that knows that Audax driver really likes it.
I think you are doing the right thing. Every driver in Australia
seems to be expensive so it seems like it is worth paying a bit more to ship in something we know is right. I'm interested in the shipping cost though. Feel free to cry here.
Remember that the real Basszilla has the woofer and vent very close to the ground. Since I am planning to bi-amp with a reasonably large bass amp, I am not so worried about the lost efficency. It is shocking how much you lose by having it high though-I'd say at least 6 dB . Since I haven't finished my second amp, I'm just using one, and I have to use an l-pad on the Fostex to reduce it's output. I might just turn the cabinet over for awhile , but I'm worried about my cats attacking it!
Remember to make the cabinet a little bigger than Dick recommends if you add bracing . Which you should!!!!! Lots!!!
But he does say to not change the width, so making it a bit deeper is the ticket. That also keeps the rear wall of the box further from the driver. Keep in mind that the internal volume is the key, and he calculated the outside dimensions based on 3/4"
wood and no bracing. Since my walls were 1.5 inches thick, I had to make it considerably bigger.
Can't wait for your report when it is done.
Mark
everyone that knows that Audax driver really likes it.
I think you are doing the right thing. Every driver in Australia
seems to be expensive so it seems like it is worth paying a bit more to ship in something we know is right. I'm interested in the shipping cost though. Feel free to cry here.
Remember that the real Basszilla has the woofer and vent very close to the ground. Since I am planning to bi-amp with a reasonably large bass amp, I am not so worried about the lost efficency. It is shocking how much you lose by having it high though-I'd say at least 6 dB . Since I haven't finished my second amp, I'm just using one, and I have to use an l-pad on the Fostex to reduce it's output. I might just turn the cabinet over for awhile , but I'm worried about my cats attacking it!
Remember to make the cabinet a little bigger than Dick recommends if you add bracing . Which you should!!!!! Lots!!!
But he does say to not change the width, so making it a bit deeper is the ticket. That also keeps the rear wall of the box further from the driver. Keep in mind that the internal volume is the key, and he calculated the outside dimensions based on 3/4"
wood and no bracing. Since my walls were 1.5 inches thick, I had to make it considerably bigger.
Can't wait for your report when it is done.
Mark
Variac,
Shipping for the Audax plus the x-overs was $158, which I thought was very reasonable. Zalytron quoted me $300, just for the Audax.
I was going to add a centre-brace from behind the woofer to the rear of the cabinet, with 3 circular holes. I was going to just stick exactly to Dick's internal measurements as per his plans.....are you saying if I add 1" thick bracing, I then need to make the cabinet deeper? Is this because the bracing sucks up a bit of the internal volume? If I use 1" bracing, just one sheet as I have described, what additional length should I add to the depth of the box??
Thanks,
Mark
Shipping for the Audax plus the x-overs was $158, which I thought was very reasonable. Zalytron quoted me $300, just for the Audax.
I was going to add a centre-brace from behind the woofer to the rear of the cabinet, with 3 circular holes. I was going to just stick exactly to Dick's internal measurements as per his plans.....are you saying if I add 1" thick bracing, I then need to make the cabinet deeper? Is this because the bracing sucks up a bit of the internal volume? If I use 1" bracing, just one sheet as I have described, what additional length should I add to the depth of the box??
Thanks,
Mark
Generally, you need to deduct the internal volume used for bracing. One option is to use rope. Glue the rope to the area where you want to brace and then soak the rope and the internal of the speaker box with epoxy resin. This should be very strong, and probably take up less internal volume.
Hey Mark,
Sorry for the delay, but I have jury duty all day so that means actually doing my job all night!
First, if you use 1" instead of 3/4" ply , you will have to make the box bigger already because I believe that Dick uses 3/4" and give exterior dimensions of the box.
I like the idea of a brace directly behind the woofer - especially if
it actually braces the woofer magnet.
I also think you need a brace from front to back at about the middle of the cabinet( right below the woofer)
Then between the middle brace and the bottom, you should probably have something- I used two pieces of square stock from front to back kind of randomly placed. In fact, stay away from neat, even divisions- Make the spacing between each brace and between each brace and wall all slightly different. That way you divide the exterior walls into panels that resonate at different frequencies. By making the box stiff with lots of bracing bracing, the subareas of each wall resonate a a higher frequency than the woofer is trying to reproduce. We have a luxury that the other drivers aren't attached to the bass box , so
area much affected by the bass box resonances either.
For this reason, I suggest that the open baffle have a base that sits on the woofer box. Between the two add a sheet of neoprene, or feet cut from a mouse pad or Sorbathane.
As far as how big to make the box, just add up the volume of all the baffles (length by width by thickness, minus the holes you have in them and the extra thickness of the walls. Increase the depth of the cabinet by the amount to equal the volume of these items.
Take additional volume needed, divided buy:
the internal height and width of the cabinet multiplied together, and
you will get the increase in depth required. Probably only an inch or two
Don't increase the length of the port slot. It's OK if it ends further from the back wall.
Sorry for the delay, but I have jury duty all day so that means actually doing my job all night!
First, if you use 1" instead of 3/4" ply , you will have to make the box bigger already because I believe that Dick uses 3/4" and give exterior dimensions of the box.
I like the idea of a brace directly behind the woofer - especially if
it actually braces the woofer magnet.
I also think you need a brace from front to back at about the middle of the cabinet( right below the woofer)
Then between the middle brace and the bottom, you should probably have something- I used two pieces of square stock from front to back kind of randomly placed. In fact, stay away from neat, even divisions- Make the spacing between each brace and between each brace and wall all slightly different. That way you divide the exterior walls into panels that resonate at different frequencies. By making the box stiff with lots of bracing bracing, the subareas of each wall resonate a a higher frequency than the woofer is trying to reproduce. We have a luxury that the other drivers aren't attached to the bass box , so
area much affected by the bass box resonances either.
For this reason, I suggest that the open baffle have a base that sits on the woofer box. Between the two add a sheet of neoprene, or feet cut from a mouse pad or Sorbathane.
As far as how big to make the box, just add up the volume of all the baffles (length by width by thickness, minus the holes you have in them and the extra thickness of the walls. Increase the depth of the cabinet by the amount to equal the volume of these items.
Take additional volume needed, divided buy:
the internal height and width of the cabinet multiplied together, and
you will get the increase in depth required. Probably only an inch or two
Don't increase the length of the port slot. It's OK if it ends further from the back wall.
With a lot of 15" drivers, small changes in box size don't seem to make a radical change in response, at least in a vented box. One consistant rule seems to be that bigger is better- It usually gets you lower bass.
I made my box considerably bigger than Dick's design, but by the time I finished, using 1.5" (38mm?) walls and a good amount of bracing, they ended up about at his recommendation!
I also wanted to make a baffle tilted down at an angle, attached to the rear of the box behind the driver. I think that such a thing
would maybe direct the waves reflected off the back of the cabinet downwards rather than back out through the cone.
Of course that creates a hollow area behind that baffle which would have to be filled with sand or something. Anyway, I ran out of room so couldn't do it.
If you make the shape less flat front to back, you get the greatest volume. Of course we worry about standing waves in a box which has a lot of similar dimensions, BUT people say for subs it doesn't matter because the wavelengths are so much larger than the cabinet dimensions.
So here's a question: If the bass box reproduces up to about 200hz, are the wavelengths still too long to worry about?
I made my box considerably bigger than Dick's design, but by the time I finished, using 1.5" (38mm?) walls and a good amount of bracing, they ended up about at his recommendation!
I also wanted to make a baffle tilted down at an angle, attached to the rear of the box behind the driver. I think that such a thing
would maybe direct the waves reflected off the back of the cabinet downwards rather than back out through the cone.
Of course that creates a hollow area behind that baffle which would have to be filled with sand or something. Anyway, I ran out of room so couldn't do it.
If you make the shape less flat front to back, you get the greatest volume. Of course we worry about standing waves in a box which has a lot of similar dimensions, BUT people say for subs it doesn't matter because the wavelengths are so much larger than the cabinet dimensions.
So here's a question: If the bass box reproduces up to about 200hz, are the wavelengths still too long to worry about?
As you may be aware, I scored some surplus JBL's that aren't a model that they sell as a component so the specs aren't available. Looks like I will be just plugging them in also.
I used some plywood with a bunch of plies thats only about $35 a sheet. Got it at Plywood and Lumber sales off Bayshore Ave.
You should make them big enough to compensate for the bracing as mentioned above of course. Also you could model the box in Win isd or equal to make sure response looks OK. It's easy since you probably have specs for the driver.
I'd invite you to hear them, but mine are dissembled, and I have jury duty for the next 5 weeks so I'm pretty stressed for time!!
Are you using the Fostex he recommends?
I used some plywood with a bunch of plies thats only about $35 a sheet. Got it at Plywood and Lumber sales off Bayshore Ave.
You should make them big enough to compensate for the bracing as mentioned above of course. Also you could model the box in Win isd or equal to make sure response looks OK. It's easy since you probably have specs for the driver.
I'd invite you to hear them, but mine are dissembled, and I have jury duty for the next 5 weeks so I'm pretty stressed for time!!
Are you using the Fostex he recommends?
I haven't bought the Fostex yet. I think I will send "the man" an email, asking him what he recommends. I think Madisound sells both of them. The older one is actually cheaper so I may just go with that. I got the plywood at Home Depot just yesterday. They cut everything for me and did not charge for the cut. I used the coupon that HD sent me for opening a credit card account and received another 10% off. So, it works out to about $40 for a full sheet. I'm planning on fiberglassing the internal of the box, and uses either plexiglass or Lexan for the Fostex baffle.
And good luck with jury duty, I just finished one at the criminal court and I was stressed out even though I'm not the one that commited an alleged crime.
And good luck with jury duty, I just finished one at the criminal court and I was stressed out even though I'm not the one that commited an alleged crime.
Well, I think Dick doesn't have an opinion yet. He says he doesn't have time until the middle of November to study the new Fostex and the tweeter that it needs. So if you want to be safe I guess the old one is the way to go. BUT, he is going to do a Basszilla update with the new one, eventually. You never know though, maybe he will hate the whole idea once he tries them. 
I guess you are right, there is a pretty big price difference between the two. Probably $150/pr all told including the tweeters. The clear baffles are a good idea. I'm amazed that they didn't occur to me what with the clear full range open baffles being discussed elsewhere here. TAP plastics on Van Ness may be a place to get plexi or polycarbonate. But the baffles are small enough that it seems that you might be able to find some thick pieces as leftovers somewhere.
My jury case is criminal and horrible. It is educational though. I think anyone should be required to go through a trial before being allowed to comment on news reports about jury decisions
I guess you are right, there is a pretty big price difference between the two. Probably $150/pr all told including the tweeters. The clear baffles are a good idea. I'm amazed that they didn't occur to me what with the clear full range open baffles being discussed elsewhere here. TAP plastics on Van Ness may be a place to get plexi or polycarbonate. But the baffles are small enough that it seems that you might be able to find some thick pieces as leftovers somewhere.
My jury case is criminal and horrible. It is educational though. I think anyone should be required to go through a trial before being allowed to comment on news reports about jury decisions
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