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Post by svart on Apr 13, 2015 12:27:21 GMT -6
I've gotten the bug to build another speaker set. I don't know why, because I've got a pile of small speakers that I use occasionally, but I've been really intrigued by the Amphion designs with the aluminum cones. I've decided to look into building a set of aluminum coned speakers using the cheaper Dayton audio drivers: www.parts-express.com/dayton-audio-rs180s-8-7-reference-shielded-woofer-8-ohm--295-364www.parts-express.com/dayton-audio-rs28a-4-1-1-8-aluminum-dome-tweeter--275-130it should be cheap since the drivers add up to about 200$, the crossover will be like 50 and boxes will be whatever you choose to use that is the right size.. So maybe like 400$ for a pair of passive monitors. However, I've downloaded a nifty crossover/box simulator and some measurement files for these drivers so I can play around with modelling the design a bit. This is going to be a relatively slow build since I've got to finish the ADC/DAC stuff and continue with the studio and day job too, but I figure I can play around with the idea for a while and learn this software and such. If anyone is interested in helping, or want to build whatever monstrosity I come up with, I'll be glad to share the design/files I come up with. |
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Post by winetree on Apr 13, 2015 15:44:25 GMT -6
Sounds like you've got your plate full, but still have the thought of what's next.
Always good to keep one step ahead. Good Luck.
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Post by svart on Apr 13, 2015 16:39:25 GMT -6
Sounds like you've got your plate full, but still have the thought of what's next. Always good to keep one step ahead. Good Luck. This is just for fun and my learning. I have zero wish to manufacture speakers! That said, i need to find a decent tweeter waveguide for this. Anyone know of one? |
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Post by svart on Apr 20, 2015 14:13:58 GMT -6
So here's the cart for the speakers I'm planning on building: Everything is from Parts Express: Dayton Audio DMPC-15 15uF 250V Polypropylene Capacitor 027-432 2 $5.98 $11.96 Dayton Audio DMPC-4.7 4.7uF 250V Polypropylene Capacitor 027-422 2 $2.79 $5.58 Dayton Audio DMPC-10 10uF 250V Polypropylene Capacitor 027-428 2 $4.72 $9.44 Dayton Audio DNR-3.0 3 Ohm 10W Precision Audio Grade Resistor 004-3 2 $1.38 $2.76 Jantzen Audio 0.50mH 20 AWG Air Core Inductor Crossover Coil 255-036 2 $6.40 $12.80 Jantzen Audio 0.75mH 18 AWG Air Core Inductor Crossover Coil 255-240 2 $7.81 $15.62 Jantzen Audio 2.2mH 18 AWG Air Core Inductor Crossover Coil 255-268 2 $13.89 $27.78 Dayton Audio RS180S-8 7" Reference Shielded Woofer 8 Ohm 295-364 2 $45.32 $90.64 Dayton Audio RS28A-4 1-1/8" Aluminum Dome Tweeter 275-130 2 $54.75 $109.50 Audyn Cap Q4 33uF 400V MKP Metalized Polypropylene Foil Crossover Capacitor 027-121 2 $9.25 $18.50 Dayton Audio DNR-6.0 6 Ohm 10W Precision Audio Grade Resistor 004-6 2 $1.38 $2.76 Jantzen Audio 0.25mH 20 AWG Air Core Inductor Crossover Coil 255-026 2 $4.25 $8.50 Audyn Cap Q4 0.82uF 400V MKP Metalized Polypropylene Foil Crossover Capacitor 027-107 2 $1.71 $3.42 I'll be building my own boxes with roughly 0.75 sqft of volume. Port is 2" x 4.6" OR 1.5" x 2.3" for a Fs of 39hz. I'm also trying to find a waveguide for the tweeter. I really like waveguides on tweeters, but finding one for DIY is almost impossible these days. I'm crossing these over as low as possible in order to keep the crucial midrange spectrum cleanly in the tweeter domain. I have no reason to do this other than anecdotal evidence that suggests metal tweeters can do this range better alone than two drivers can together, and I have an interest in seeing what will happen when taking an unconventional approach to crossover frequencies. This is the response I get from the crossover design using the models taken from actual speaker measurement files:  |
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kcatthedog
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Post by kcatthedog on Apr 20, 2015 18:34:14 GMT -6
cool what happens in the bermuda triangle at 1k between the black red and blue ?
p.s. if your line is like +- 2/3 db isn't that awfully good; that is looking awfully flat, little low bass bloom, no biggie ?
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Post by svart on Apr 20, 2015 18:49:52 GMT -6
cool what happens in the bermuda triangle at 1k between the black red and blue ? p.s. if your line is like +- 2/3 db isn't that awfully good; that is looking awfully flat, little low bass bloom, no biggie ? The red is the tweeter response, the blue is the woofer, the black is the sum of the two, and is what you'd hear. The response is pretty good considering using lower order filters. |
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Post by kcatthedog on Apr 20, 2015 19:16:52 GMT -6
ah they sum so are actually quite flat there; thx !
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Post by svart on Apr 20, 2015 19:34:14 GMT -6
Also, the grey line is the expected enclosure rresponse. You can see it extends the respons quite low.
I'm excited to build these, but it'll still be some time before i do, i think.
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Post by svart on Apr 21, 2015 8:44:27 GMT -6
Crossover.pdf (6.07 KB) <-------------------------------------------------- Crossover schematic---------------------------- Here's the crossover I intend to build. The woofer is a 4th order standard LPF. The tweeter is a 2nd order crossover with a tilt compensator and a light notch filter to flatten the top end response and to squish a resonance peak, respectively.
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Post by kcatthedog on Apr 21, 2015 9:01:36 GMT -6
well please keep us posted. I am definitely interested.
Do you have your amps picked out or do you have them already ?
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Post by svart on Apr 21, 2015 10:04:58 GMT -6
well please keep us posted. I am definitely interested. Do you have your amps picked out or do you have them already ? Just going to use my home stereo or my gainclone for starters so I can compare to what I already know! |
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Post by kcatthedog on Apr 21, 2015 10:39:19 GMT -6
good plan !
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Post by svart on Apr 21, 2015 13:47:30 GMT -6
Also, the box I plan to make is 8"W x 15"T x 10.75"D for a total volume of roughly 0.75 cubic feet. The tweeter should be recessed by 1", either by waveguide or by a step in order to time align it with the woofer.
I'm putting the port on the back, but some folks like them on the front.
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Post by kcatthedog on Apr 21, 2015 14:26:37 GMT -6
I know they say due to bass notes omnidirectionality it doesn't matter, but I feel that I prefer front ports, so not closed like amphion ?
what's your take on overhang etc.. ?
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Post by svart on Apr 22, 2015 7:17:23 GMT -6
I know they say due to bass notes omnidirectionality it doesn't matter, but I feel that I prefer front ports, so not closed like amphion ? what's your take on overhang etc.. ? I think overhang is relative to the design and the modes created in the cabinet, and it's not something that can be modeled without serious 3D modelers. The other one is "chuffing", which can be handled by using flared ports, or much wider/longer ports. This is also something that needs to be listened to and tuned. I'd like to try doing passive radiators, but I don't know how to simulate them properly. I might make a couple test boxes and see what happens when I use radiators instead of ports. |
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Post by kcatthedog on Apr 22, 2015 7:20:39 GMT -6
ya interesting there must be documentation about radiator design as in what is the relationship between the enclosure characteristic, eh speakers and the size/composition of the radiator. I like the idea of apparent but clear bass , no woof  |
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Post by svart on Apr 22, 2015 8:28:54 GMT -6
ya interesting there must be documentation about radiator design as in what is the relationship between the enclosure characteristic, eh speakers and the size/composition of the radiator. I like the idea of apparent but clear bass , no woof Some folks seem to dislike passive radiators for one main reason, they are slower to react than air loading, which makes the low end become smeared in some designs. It takes quite a bit of study and knowledge to design around these issues apparently. it's not as straight-forward as finding a specific size radiator, a lot of physical testing and matching to the woofer/enclosure seems to be required. I think flared ports in the back are the best option right now, at least for my build. |
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Post by svart on Apr 28, 2015 14:58:20 GMT -6
I ordered the parts for these monitors. I'll go get some wood this week and make some temporary cabinets for them. I also got some cheap plastic waveguides for the tweeters since I want to recess them into the speaker to time-align the coils better. They don't have any real mounting points so they'll need machining and some rigging to get them working with the tweeters I think.
I'll keep this updated.
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Post by markfouxman on Apr 28, 2015 18:28:50 GMT -6
I love sound of Al drivers. They have clarity and transparency of good ribbon speakers, but free of many of their image and sensitivity problems. I have NHT XdS with very expensive magnesium Seas woofer and Al Seas tweeter and they are absolutely superb! The drivers you mentioned are highly regarded and would probably give you about 90% of the Seas sound quality (at least 4 times cheaper).
Your biggest enemy here is a woofer breakup (inevitable in any Al cone) at 6.8kHz. On one hand you want to cross the drivers as low as possible to get further away from it, on another, you are limited with tweeter Fs and how loud you want to play. As a rule of thumb with second order on a tweeter you want your crossover point to be at least a couple octaves higher than Fs, otherwise you will start straining your tweeter. You might also consider putting LR4 to make tweeter's life easier.
Another consideration, you don't want the crossover point to go way low, as it is the most sensitive ear range, so any crossover imperfections will be noticeable. Looking at the graphs it looks like 2.3kHz might be a good sweet spot where the woofer response starts falling and you can use it at your advantage. You also might look at LR3, which together with acoustical 1st order would give you an overall 4th order. You probably still would want to take additional care of that breakup peak with a notch, as it might give that sound edge and harshness (wrongly) associated with Al drivers.
The waveguide can be tricky. While it has its advantages (time alignment not the least) depending on the tuning it will also raise the output in some 1kHz-6kHz range. You will need to really scratch your head how to deal with that. The easiest way would probably be using a DSP to shape the responses and quickly find optimal crossover points. If you have a calibrated mic and a good measuring system that will be quite easy to tune everything nicely. With passive crossover it can be more of a challenge...
Best, M
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Post by Deleted on Apr 28, 2015 20:44:04 GMT -6
Hi svart, did you use something like Akabak to simulate your cabinet?
Still have it on an older drive but have no compatible OS anymore and would have to install a virtual machine to get it running again...
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Post by svart on Apr 29, 2015 9:13:58 GMT -6
I love sound of Al drivers. They have clarity and transparency of good ribbon speakers, but free of many of their image and sensitivity problems. I have NHT XdS with very expensive magnesium Seas woofer and Al Seas tweeter and they are absolutely superb! The drivers you mentioned are highly regarded and would probably give you about 90% of the Seas sound quality (at least 4 times cheaper). Your biggest enemy here is a woofer breakup (inevitable in any Al cone) at 6.8kHz. On one hand you want to cross the drivers as low as possible to get further away from it, on another, you are limited with tweeter Fs and how loud you want to play. As a rule of thumb with second order on a tweeter you want your crossover point to be at least a couple octaves higher than Fs, otherwise you will start straining your tweeter. You might also consider putting LR4 to make tweeter's life easier. Another consideration, you don't want the crossover point to go way low, as it is the most sensitive ear range, so any crossover imperfections will be noticeable. Looking at the graphs it looks like 2.3kHz might be a good sweet spot where the woofer response starts falling and you can use it at your advantage. You also might look at LR3, which together with acoustical 1st order would give you an overall 4th order. You probably still would want to take additional care of that breakup peak with a notch, as it might give that sound edge and harshness (wrongly) associated with Al drivers. The waveguide can be tricky. While it has its advantages (time alignment not the least) depending on the tuning it will also raise the output in some 1kHz-6kHz range. You will need to really scratch your head how to deal with that. The easiest way would probably be using a DSP to shape the responses and quickly find optimal crossover points. If you have a calibrated mic and a good measuring system that will be quite easy to tune everything nicely. With passive crossover it can be more of a challenge... Best, M Excellent post. The breakup on the woofer for the dayton is indeed harsh! Besides using a 4 pole LPF on it, I decided to move the crossover down further. The tweeter had a very nice curve to begin with, and a lot of users have mentioned good results around 1400-1500 corner frequency, so I targeted 1500 for the corner and only had to move the rolloff up a few hundred hertz, and then match the output, which was much hotter than the woofer. I figure that the worst that would happen is I have to redo the crossover at a higher point. |
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Post by svart on Apr 29, 2015 9:15:04 GMT -6
Hi svart, did you use something like Akabak to simulate your cabinet? Still have it on an older drive but have no compatible OS anymore and would have to install a virtual machine to get it running again... I used an excel spreadsheet in "passive crossover designer 7" for the box dimensions and port diameter/length. |
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Post by markfouxman on Apr 29, 2015 16:40:08 GMT -6
I targeted 1500 for the corner and only had to move the rolloff up a few hundred hertz, and then match the output, which was much hotter than the woofer. Ah, that explains it. On the graph the crossover point looked awfully close to 1kHz, which would really be pushing things... Best, M |
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Post by svart on Apr 30, 2015 7:04:48 GMT -6
I targeted 1500 for the corner and only had to move the rolloff up a few hundred hertz, and then match the output, which was much hotter than the woofer. Ah, that explains it. On the graph the crossover point looked awfully close to 1kHz, which would really be pushing things... Best, M It does, but the tweeter has a dip around that area, so the crossover point graphically looks lower than it is mathematically. The woofer also has a slight peak in that area too, so the woofer corner is lower than 1KHz, but the peak brings it up to match the tweeter rolloff at a higher frequency. These graphs are made from actual frequency graphs taken from speakers. I have a few different files for each and they are all only slightly different, so I suspect that the graphs are a good representation of the speakers themselves, with all the peaks and dips. |
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Post by svart on May 4, 2015 11:57:58 GMT -6
So although I was sick over the weekend, I still made some time to put together my crossovers and cut out a test panel for woofer/tweeter placement. I started with the flat faced one, without the waveguide.
I did a simple test of the front baffle with the drivers loaded just to see what I could hear from it. I was pretty surprised at how wide the tweeter image was. There weren't any significant hotspots/beaming like I had expected. Maybe this is because I haven't used a domed tweeter for anything in a long time and had forgotten how wide the pattern is.
In any case, the crossover worked as expected. I haven't built the boxes yet, so that remains to be done.
So far I expect these to sound pretty good. I think the tweeter might be a little hot compared to the woofer, but it's hard to tell without the box.
Also, the woofer is 7" on the OD of the mounting rim, but there is quite a bit of distance between the rim and the surround. I'd say that the woofer cone actually measures closer to that of a 6-6.5" speaker than a true 7".
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