my first two way speaker build. these have to fit in a drawer in a large buffet that our tv sits on. (women are the enemy of speakers) so the primary goal here is good deep bass. a flat frequency response is not a huge priority +/- 10db is a fine goal here.
So here are the drivers...
Dayton Audio PC83-8 3" Full-Range Poly Cone Driver
Dayton Audio TCP115-4 4" Treated Paper Cone Midbass Woofer 4 Ohm
my plan is to wire two of the 4" in series to give me 8 ohms for the woofers and the full range. The speaker will be 7" wide X 7" deep X 27" tall. (not ideal i know, that's the biggest boxes I can get to fit in the drawer) it's going to be made from 1/2" pine. The full range chamber will be on top, 6x6x3 inches and sealed giving .0625 ft^3. The woofer chamber will be 6x6x22 giving 0.45ft^3. I'm going to tune the woofers to 33hz. (i know, bear with me here) That gets us down to 35ish hz at f6 and 105ish f3. The two drivers have very similar spl ratings, i think 1.2db difference in favor of the woofer, so for this project we can say they are the same. On the full range i'm going to do a baffle step/zoble for 4db.(calculator on mh-audio website) 7" baffle is 651ish hz. I was going to run the top full range relying on the natural roll off of the sealed enclosure, that just so happens to have an f3 at 105hz. so does this sound right? full range will be at -4 db. woofer will loose 6 for being under the baffle step, but gain 3 for being two drivers. so full range is at -4db and woofer is at -3db, so pretty much even up to here at the 105hz mark. then the woofer will lose 3 more on its way down to 35hz. the woofer is going to have a first order 12mh coil on it that puts it right in that 105hz range.
Is my logic correct? these are cheap drivers, not for critical listening, that will only hit 80-85db, and i'm fine with all that.
I'm going glue cabinet carpet for the finish since they will be moved around a lot, and to help with diffraction. I'm going to use two 3/4 pvc tubes for the reflex port, cut to 5.35" (winisd still puts that in the red for vent mach but i think it's close enough, they will never get played at full volume) or i might do a right angle bend on a single 2".
So here are the drivers...
Dayton Audio PC83-8 3" Full-Range Poly Cone Driver
Dayton Audio TCP115-4 4" Treated Paper Cone Midbass Woofer 4 Ohm
my plan is to wire two of the 4" in series to give me 8 ohms for the woofers and the full range. The speaker will be 7" wide X 7" deep X 27" tall. (not ideal i know, that's the biggest boxes I can get to fit in the drawer) it's going to be made from 1/2" pine. The full range chamber will be on top, 6x6x3 inches and sealed giving .0625 ft^3. The woofer chamber will be 6x6x22 giving 0.45ft^3. I'm going to tune the woofers to 33hz. (i know, bear with me here) That gets us down to 35ish hz at f6 and 105ish f3. The two drivers have very similar spl ratings, i think 1.2db difference in favor of the woofer, so for this project we can say they are the same. On the full range i'm going to do a baffle step/zoble for 4db.(calculator on mh-audio website) 7" baffle is 651ish hz. I was going to run the top full range relying on the natural roll off of the sealed enclosure, that just so happens to have an f3 at 105hz. so does this sound right? full range will be at -4 db. woofer will loose 6 for being under the baffle step, but gain 3 for being two drivers. so full range is at -4db and woofer is at -3db, so pretty much even up to here at the 105hz mark. then the woofer will lose 3 more on its way down to 35hz. the woofer is going to have a first order 12mh coil on it that puts it right in that 105hz range.
Is my logic correct? these are cheap drivers, not for critical listening, that will only hit 80-85db, and i'm fine with all that.
I'm going glue cabinet carpet for the finish since they will be moved around a lot, and to help with diffraction. I'm going to use two 3/4 pvc tubes for the reflex port, cut to 5.35" (winisd still puts that in the red for vent mach but i think it's close enough, they will never get played at full volume) or i might do a right angle bend on a single 2".
How about a little more money in the woofers, and a regular tweeter? Or, an array of 3 of those full rangers, without a crossover? 🙂
With such wide range drivers all close together and no significant crossover you are going to get awful phase combing effects. For this to sound good you really will need some form of crossover.
If you don’t want to do a crossover, I would think a single full range would give you a much better response. For the smae money as your three drivers you could have one of these,
https://www.parts-express.com/pedocs/specs/295-378-dayton-audio-rs100-4-spec-sheet-revised.pdf
Which will give you a farily flat frequency reponse, a 4 ohm load and good off axis response so the TV will sound OK from most locations in the room.
If you don’t want to do a crossover, I would think a single full range would give you a much better response. For the smae money as your three drivers you could have one of these,
https://www.parts-express.com/pedocs/specs/295-378-dayton-audio-rs100-4-spec-sheet-revised.pdf
Which will give you a farily flat frequency reponse, a 4 ohm load and good off axis response so the TV will sound OK from most locations in the room.
what would constitute a significant crossover do you think? higher order on the low pass? i was planning on a first order low pass with 12mh. should the full range have a crossover too? i picked the 4” speakers bassed on that they will get pretty low in a small box.
Hi Cramer, I would propose a different solution, like all three drivers be in the same enclosure placed normal as if this were a free single standing standard loudspeaker. The woofers can be a little larger to dig a little better since this makes a notable difference. Let me take a look what Dayton Audio has got to offer and I'll make you a simple and affordable crossover by simulating, if you agree to that. Are your drivers already purchased?
havnt bought anything yet. they are two chambers in a single box. i just thought i would need to separate the full range to keep the woofers from pushing the full range around.
thats what i was thinking too, except standing vertically from the floor. my goal is cheap, deep bass, in a small box, but giving up total db output. and beat whats premade or a kit from parts express. that c-note kit looks good, but i want to get below 40hz. i was also toying with the idea of that kit and build a bigger box to get the bass deeper.
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Sorry I misread the bit on the 12mH inductor. A first order on the bass is not ideal as the box roll off will be second order but its very low in frequency, so you are basically running the bass drivers as a sub and using the full range accross the rest of the response.
That should be OK. But if Lojzek is happy to do a simulation for you I would take him up on it, you will probably get a much better result that way.
Sorry for my confusion over the bass inductor, I should have read it more carefully.
Andy
That should be OK. But if Lojzek is happy to do a simulation for you I would take him up on it, you will probably get a much better result that way.
Sorry for my confusion over the bass inductor, I should have read it more carefully.
Andy
As I had some spare time and it looked like an interesting challenge. I had a go at a simulation of your current proposal. It was not easy as you are using acoustic roll off for half the crossover but I think I have got something fairly close.
The two bass drivers are in an enclosure that is 12.7L size (This is far too small for a no peaking response) I don't understand your comment it will be tuned to 35Hz as in this enclosure the bass is no where near 35Hz. Any enclosure will push Fs up and you started at higher then 35Hz.
The full range is in a 1.7L enclosure, I have added baffle simulation to it to simulate the half space to full space level loss. Keep in mind if this is near a wall you will get a lot of it back again (a little later) from the reflection.
The 14mH inductor seems to do and OK job of integrating the two but I would think that this design will lack deep bass as boom at bit at the peak. If I have misunderstood something then let me know and I will try to correct it.
The two bass drivers are in an enclosure that is 12.7L size (This is far too small for a no peaking response) I don't understand your comment it will be tuned to 35Hz as in this enclosure the bass is no where near 35Hz. Any enclosure will push Fs up and you started at higher then 35Hz.
The full range is in a 1.7L enclosure, I have added baffle simulation to it to simulate the half space to full space level loss. Keep in mind if this is near a wall you will get a lot of it back again (a little later) from the reflection.
The 14mH inductor seems to do and OK job of integrating the two but I would think that this design will lack deep bass as boom at bit at the peak. If I have misunderstood something then let me know and I will try to correct it.
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this is just a quick thank you for doing this for me. later today ill show you what winisd was telling me, only tool ive got for this sort of thing. ill draw up the side view on some graph paper too.
so the 3rd grader level drawing each block is a half inch. one image of winisd is just the two bass drivers showing box volume and tuning. the other winisd pic is the spl of all the drivers together and showing the port mach of the bass drivers.
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Ok what I hadnt appreciated was that you intended to use a ported enclosure. I can rework it for that now I have the info.
Andy
Andy
I have now simulated your extended bass shelf bass solution. and combined it with the full range with the 1.7L enclosure. I have not added baffle diffraction and loss to this but it would raise the 1K region and reduce the low frequency.
As you can see this is going to give you a lumpy bass response.
As you can see this is going to give you a lumpy bass response.
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What are you trying to achieve and I will see if I can find a better solution within your constraints.
Currently I see you plan to use a 1.7L top enclosure and a 13.5L lower enclosure with a port. An a driver set cost of approx. $30 per speaker
Would you like to stick with the full range with Bass support solution? (Or would you consider a tweeter / bass solution)
Are you happy to modify the relative volumes a bit to provide smoother bass alignment if it stays within the same basic dimensions?
34Hz is an extremely aggressive bass alignment target for a speaker of this size and cost would you consider compromising on the deep bass a bit. Something at 45-50Hz would be much easier to achieve and would probably integrate into a small room better.
Currently I see you plan to use a 1.7L top enclosure and a 13.5L lower enclosure with a port. An a driver set cost of approx. $30 per speaker
Would you like to stick with the full range with Bass support solution? (Or would you consider a tweeter / bass solution)
Are you happy to modify the relative volumes a bit to provide smoother bass alignment if it stays within the same basic dimensions?
34Hz is an extremely aggressive bass alignment target for a speaker of this size and cost would you consider compromising on the deep bass a bit. Something at 45-50Hz would be much easier to achieve and would probably integrate into a small room better.
would reducing the full range chamber raise the full range f3 enough to flatten that lump out? i asume its the combination of two gentle cross over slopes summing together? when i tried that on winisd it looked like the phase got wierd at the xover point but if them being out of phase helps flatten that down? what would you suggest?
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