After getting some great tips on extracting phase from response graphs, I'm well on my way to building some speakers for a small home theater setup. I thought I'd start a new thread, journaling the process from design to finished.
Of course, a lot of that design has already happened so some of this will be catching up with what I've done so far.
Warning in advance: I like to write! I write a lot and I put a lot of detail into what I write. That means my posts can be time consuming to write and definitely to read. So grab a drink and follow on...
The thread is definitely open to all comments, critiques and suggestions as I learn most by seeing what others have done and getting a read from others on what works and what doesn't.
First up, some background:
I ended up with a "spare" set of tweeters due to a shipping mishap back when this project started and have been sitting on them ever since. That and some time on my hands, and the bug to build has awakened!
The 850122 is no longer around so I couldn't simply build another set of PeeCreeks. Peerless hasn't exactly sat on its laurels with 6.5" drivers though. We've got a nice selection of alternatives now, namely the 830875, 830874 and 830883. All are "upper end" with cast baskets, good cone materials, shorting rings in the motors, great ventilation, and attractive designs (though the 830883 isn't everyone's cup of tea with the silver basket).
Anyway, budget and ease of design (I don't love the upper peaks of the 830883) won out in the end and I went with the 830874 for the replacement drop ins for the older design I once built. Of course the crossovers and overall cabinet design will likely change as well. In fact, I'll probably redo the high pass for the tweeters, even.
While I was working on the mains, why not do a center channel as well? Lots of research and head scratching later, I've settled on a small sealed 3 way, using Peerless again for midbass (2x 5.25 830656 paper cone) and midrange (an 830870 4" PP) and an SB Acoustic 1" for the tweeter (SB26STC). I went 3 way to avoid the dispersion issues of a side mounted MTM and to get some experience working with a 3 way crossover as I need a bit of a challenge.
The boxes will all be sealed alignment with QTC of around .8 from my simulated models. I'll be using a 12" active sub and the room is pretty small.
Lots of questions to follow as my design goals are to get all the drivers in, measured, enclosures built based on the measurements, and then design and order the crossover components. This seems to be the best way to approach a new project.
Of course, a lot of that design has already happened so some of this will be catching up with what I've done so far.
Warning in advance: I like to write! I write a lot and I put a lot of detail into what I write. That means my posts can be time consuming to write and definitely to read. So grab a drink and follow on...
The thread is definitely open to all comments, critiques and suggestions as I learn most by seeing what others have done and getting a read from others on what works and what doesn't.
First up, some background:
- Last completed project was done in 2004 so it's been well over 10 years ago that I last worked on anything.
- My projects before that were numerous (built small 2-way bookshelf, large 3-way floorstanding, slender 2-way tower, experimented with a sub...) but never used any sort of measurements to make it all come together. I relied almost completely on textbook calculators and published DIY designs.
- The last project was one I got from Parts-Express DIY boards if I recall, the "PeeCreek" using a Peerless 850122 6.5" paired with a North Creek Music Systems D25 1" "matched" dome tweeters.
- See archived site here.
- They worked very well and I was pleased to have built a nice set of speakers for the living room.
I ended up with a "spare" set of tweeters due to a shipping mishap back when this project started and have been sitting on them ever since. That and some time on my hands, and the bug to build has awakened!
The 850122 is no longer around so I couldn't simply build another set of PeeCreeks. Peerless hasn't exactly sat on its laurels with 6.5" drivers though. We've got a nice selection of alternatives now, namely the 830875, 830874 and 830883. All are "upper end" with cast baskets, good cone materials, shorting rings in the motors, great ventilation, and attractive designs (though the 830883 isn't everyone's cup of tea with the silver basket).
Anyway, budget and ease of design (I don't love the upper peaks of the 830883) won out in the end and I went with the 830874 for the replacement drop ins for the older design I once built. Of course the crossovers and overall cabinet design will likely change as well. In fact, I'll probably redo the high pass for the tweeters, even.
While I was working on the mains, why not do a center channel as well? Lots of research and head scratching later, I've settled on a small sealed 3 way, using Peerless again for midbass (2x 5.25 830656 paper cone) and midrange (an 830870 4" PP) and an SB Acoustic 1" for the tweeter (SB26STC). I went 3 way to avoid the dispersion issues of a side mounted MTM and to get some experience working with a 3 way crossover as I need a bit of a challenge.
The boxes will all be sealed alignment with QTC of around .8 from my simulated models. I'll be using a 12" active sub and the room is pretty small.
Lots of questions to follow as my design goals are to get all the drivers in, measured, enclosures built based on the measurements, and then design and order the crossover components. This seems to be the best way to approach a new project.
Hi Micky
I just posted the LM-1 and Lm-1c projects here
A Speaker Maker's Journey: Introduction to The W. Marshal Leach Jr. Memorial Speakers
I stuck with a Vifa XT25 and Peerless 830991. The f3 and sensitivity are close to your woofer, but have a little leaa power handling. Also, the 830991 has a better FR. it may not matter to you based on your crossover, but i hope you find all the data i posted useful.
Best,
Erik
I just posted the LM-1 and Lm-1c projects here
A Speaker Maker's Journey: Introduction to The W. Marshal Leach Jr. Memorial Speakers
I stuck with a Vifa XT25 and Peerless 830991. The f3 and sensitivity are close to your woofer, but have a little leaa power handling. Also, the 830991 has a better FR. it may not matter to you based on your crossover, but i hope you find all the data i posted useful.
Best,
Erik
Quick question:
My baffle on the center will likely be very short (narrow for a standard tall speaker) at about 7". I'm toying with overlapping the mid and tweeter so it will fit into this space. Is there any problem with closely mounted drivers and a low crossover frequency?
I'm getting a recommended frequency of around 5khz but plan to cross at about 3khz. I know there are lobing issues if you pick too high a frequency and the drivers aren't close enough. But is there any issue if your drivers are closer than required?
My baffle on the center will likely be very short (narrow for a standard tall speaker) at about 7". I'm toying with overlapping the mid and tweeter so it will fit into this space. Is there any problem with closely mounted drivers and a low crossover frequency?
I'm getting a recommended frequency of around 5khz but plan to cross at about 3khz. I know there are lobing issues if you pick too high a frequency and the drivers aren't close enough. But is there any issue if your drivers are closer than required?
Some further (very late) updates. I've settled on layouts and crossover frequencies, as well as bought all the drivers. The tweeter is an SB Acoustics SB26STCN small flange driver so I can mount it closer to the Peerless 830870 4" mid driver.
I'll go with a 3 way design with 2 Peerless 830656 5.25" treated paper woofers on either side of the 4" and 1" drivers.
I'm still playing with crossover options so haven't ordered the final components yet. will be about 650hz between the woofer and mid, and 2.5khz(ish) between the mid and tweet. I'll post up some simulated measurements when I get it tweaked properly. I seem to be having issues with getting a deep enough null when I reverse the polarity. The joys of 3 way simulations I think.
The sub is done enough to be thoroughly enjoying its presence with my old PeeCreek front speakers and a really lousy Dayton "budget" centre channel using the paper coned shielded 5.25" woofers and the old shielded "silky" tweeter. The centre is what I'd describe as obviously "honky" and I can't wait to get this new design built and added to what's shaping up to be a very satisfying system.
The rear channels are based loosely on the "Dayton Budget Project" using the same two drivers I have in the centre. I built them using a smaller sealed design though, and tweaked the crossover to better address the peaking I measured with the woofers. Not sure if the design changed somewhere during production, but mine didn't measure anywhere near what the spec sheet showed.
It's all coming along nicely, albeit slowly.
I'll go with a 3 way design with 2 Peerless 830656 5.25" treated paper woofers on either side of the 4" and 1" drivers.
I'm still playing with crossover options so haven't ordered the final components yet. will be about 650hz between the woofer and mid, and 2.5khz(ish) between the mid and tweet. I'll post up some simulated measurements when I get it tweaked properly. I seem to be having issues with getting a deep enough null when I reverse the polarity. The joys of 3 way simulations I think.
The sub is done enough to be thoroughly enjoying its presence with my old PeeCreek front speakers and a really lousy Dayton "budget" centre channel using the paper coned shielded 5.25" woofers and the old shielded "silky" tweeter. The centre is what I'd describe as obviously "honky" and I can't wait to get this new design built and added to what's shaping up to be a very satisfying system.
The rear channels are based loosely on the "Dayton Budget Project" using the same two drivers I have in the centre. I built them using a smaller sealed design though, and tweaked the crossover to better address the peaking I measured with the woofers. Not sure if the design changed somewhere during production, but mine didn't measure anywhere near what the spec sheet showed.
It's all coming along nicely, albeit slowly.
This project has all components ordered, cabinet is cut but not assembled and even the driver holes and recesses are cut. I've modelled the crossovers and bought components, even without measuring. I may need to tweak things a bit after assembly and testing.
That's for the center speaker.
Rears are done, the sub is done but cabinets are not finished, the fronts are cut and drivers sorted but no crossovers yet.
That's for the center speaker.
Rears are done, the sub is done but cabinets are not finished, the fronts are cut and drivers sorted but no crossovers yet.
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