Hello, this is a long post, but please bear with me...
I am new to speaker building, and have already done what some might consider a big "no-no": I bought a pair of Supravox 165 GMF drivers, simply based on some positive reviews and out of a positive gut feeling 🙂.
Nevertheless, I am quite impressed. I mounted them into a mini-baffle for experimentation purposes, and tried them in my office system, and then my living room:
I love the realistic sound, especially of piano, organ, drums, percussion etc. in the midrange.
In my livingroom I have an active crossover (Pioneer D-23) which allowed me to try them at various crossover points and slopes with the tweeter and woofers of my current 3-way speakers (which don't use the original active system anymore).
I used some boards to create a larger baffle, "boxed up" the Supravox baffle with some MDF boards and clamps etc. I definitely liked the Supravox on an open baffle the best, "boxed up" it lost its charm.
Then I added a Hiquphon OW3 tweeter to the baffle, which added the missing "sparkle":
and also took some measurements. With the baffle around the Supravox extended to about 15" width, but nothing added around the tweeter, the frequency response looked quite nice above 1000 Hz.
Crossover points were:
Woofers up to 630 Hz, 6 db slope
Supravox from 630 Hz to 4000 Hz, 6 db slope
Hiquphon from 3200 Hz to ∞, 6 db slope
FR measured from listening position, pointed at tweeter:
My room is far from ideal, which is evident in the lower spectrum of the graph.
Now, I realize of course that these were all just very crude experiments, but I just had to get my feet wet and play around a bit, there is no better way to learn...
My thinking now is, to build "hybrid" open baffle 3-way, similar to this design:
... with the Pioneer active crossover, which I eventually intend to replace with a DIY active crossover (I just started reading Douglas Self's book on active crossovers).
What I don't have yet is a woofer. After a lot of reading here and on other sites/books, I decided that I would probably be happier with a sealed enclosure. I don't need 20 Hz bass, would prefer a smooth roll-off, and prefer the simpler implementation (I am new to this...).
I believe the ScanSpeak Discovery 30W/4558T would work well. I modeled it in Unibox and also in Speakerbuilder Pro 2.0 and got pretty nice looking results for a box at around 55l and an Fb of 36.17 Hz:
The Unibox results looked pretty much the same.
Questions about this idea:
1) Does this all make sense at all?
2) Did I model the woofer correctly?
3) What, besides stuffing, bracing, and non-multiple length panels on the woofer box do I need to worry about?
4) If I run the woofer up to 630 Hz or even higher, do I need to worry about standing waves in the enclosure? Would a "Triangular Prism" shape be worth the trouble?
5) Since the Hiquophon has a much lower sensitivity than the Supravox, would I be better off using a tweeter with higher sensitivity, even though the active crossover could easily compensate for the difference?
6) What other graphs should I examine in my REW measurements?
I realize some may disagree on using an active crossover, but my limited experience was very positive, I already have the amps, the Pioneer D-23, the book... so I want to stick with that idea.
My amps are all solid state amps, in case you wonder...
I should also mention that I have somewhat intermediate woodworking skills and a woodworking shop in the basement.
I am new to speaker building, and have already done what some might consider a big "no-no": I bought a pair of Supravox 165 GMF drivers, simply based on some positive reviews and out of a positive gut feeling 🙂.
Nevertheless, I am quite impressed. I mounted them into a mini-baffle for experimentation purposes, and tried them in my office system, and then my living room:
I love the realistic sound, especially of piano, organ, drums, percussion etc. in the midrange.
In my livingroom I have an active crossover (Pioneer D-23) which allowed me to try them at various crossover points and slopes with the tweeter and woofers of my current 3-way speakers (which don't use the original active system anymore).
I used some boards to create a larger baffle, "boxed up" the Supravox baffle with some MDF boards and clamps etc. I definitely liked the Supravox on an open baffle the best, "boxed up" it lost its charm.
Then I added a Hiquphon OW3 tweeter to the baffle, which added the missing "sparkle":
and also took some measurements. With the baffle around the Supravox extended to about 15" width, but nothing added around the tweeter, the frequency response looked quite nice above 1000 Hz.
Crossover points were:
Woofers up to 630 Hz, 6 db slope
Supravox from 630 Hz to 4000 Hz, 6 db slope
Hiquphon from 3200 Hz to ∞, 6 db slope
FR measured from listening position, pointed at tweeter:
My room is far from ideal, which is evident in the lower spectrum of the graph.
Now, I realize of course that these were all just very crude experiments, but I just had to get my feet wet and play around a bit, there is no better way to learn...
My thinking now is, to build "hybrid" open baffle 3-way, similar to this design:
... with the Pioneer active crossover, which I eventually intend to replace with a DIY active crossover (I just started reading Douglas Self's book on active crossovers).
What I don't have yet is a woofer. After a lot of reading here and on other sites/books, I decided that I would probably be happier with a sealed enclosure. I don't need 20 Hz bass, would prefer a smooth roll-off, and prefer the simpler implementation (I am new to this...).
I believe the ScanSpeak Discovery 30W/4558T would work well. I modeled it in Unibox and also in Speakerbuilder Pro 2.0 and got pretty nice looking results for a box at around 55l and an Fb of 36.17 Hz:
The Unibox results looked pretty much the same.
Questions about this idea:
1) Does this all make sense at all?
2) Did I model the woofer correctly?
3) What, besides stuffing, bracing, and non-multiple length panels on the woofer box do I need to worry about?
4) If I run the woofer up to 630 Hz or even higher, do I need to worry about standing waves in the enclosure? Would a "Triangular Prism" shape be worth the trouble?
5) Since the Hiquophon has a much lower sensitivity than the Supravox, would I be better off using a tweeter with higher sensitivity, even though the active crossover could easily compensate for the difference?
6) What other graphs should I examine in my REW measurements?
I realize some may disagree on using an active crossover, but my limited experience was very positive, I already have the amps, the Pioneer D-23, the book... so I want to stick with that idea.
My amps are all solid state amps, in case you wonder...
I should also mention that I have somewhat intermediate woodworking skills and a woodworking shop in the basement.
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The ScanSpeak 30W/4558T is a dedicated subwoofer (low Fs; heavy cone); I would not use it up to 630 Hz. Also typical cone break up only 2 octaves above 600 Hz.
IMO open baffles excel especially in mid/bass and low/mid.
Currently I am working on an open baffle with two 15 inch Beyma woofers, up to some 350 Hz (actually one woofer up to 350 Hz, the lower one up to 100 Hz), with a combination of Audax HM210Z10 and Beyma TPL150 for mid and treble.
Your Supravox should work very well with a 300 Hz or so crossover.
When there is lack of low bass, I have a pair of the ScanSpeak 30W for an additional actively powered sealed sub.
Much time will be spent in designing/tuning the passive crossover for the prototype open baffle (a 2 x 4 ft 22 mm sheet of MDF), and building a final baffle when the result is good enough.
IMO open baffles excel especially in mid/bass and low/mid.
Currently I am working on an open baffle with two 15 inch Beyma woofers, up to some 350 Hz (actually one woofer up to 350 Hz, the lower one up to 100 Hz), with a combination of Audax HM210Z10 and Beyma TPL150 for mid and treble.
Your Supravox should work very well with a 300 Hz or so crossover.
When there is lack of low bass, I have a pair of the ScanSpeak 30W for an additional actively powered sealed sub.
Much time will be spent in designing/tuning the passive crossover for the prototype open baffle (a 2 x 4 ft 22 mm sheet of MDF), and building a final baffle when the result is good enough.
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Thanks for your response.
Is your verdict that I should not use a subwoofer-style woofer at all then, or just not cross it that high?
I admit I have never heard a woofer on an open baffle, it seems that you prefer that over a boxed woofer?
Based on previous experience I prefer to go OB as low as possible, but open baffles obviously have their limitations to reproduce low bass. For some music (small scale chamber music for example) that does not hurt. For other genres (rock; large scale symphonic) the lack of low bass calls for additional woof-woof.
My advice would be to build OB bass with a 15 inch woofer and see how far you will get; there are many examples to be found on WWW. The ScanSpeak woofer up to 630 Hz will not work as good, especially when you will filter it first order (the 2k5 cone break up will be very audible).
My advice would be to build OB bass with a 15 inch woofer and see how far you will get; there are many examples to be found on WWW. The ScanSpeak woofer up to 630 Hz will not work as good, especially when you will filter it first order (the 2k5 cone break up will be very audible).
That was my understanding, too, and why I thought a hybrid design with a sealed woofer would be better.
I didn't mention what music I usually listen to. Funk/Soul, Jazz, Classic Rock... well, basically a lot of music that really depends on great bass grooves, so I may be better off with a box...
I didn't mention what music I usually listen to. Funk/Soul, Jazz, Classic Rock... well, basically a lot of music that really depends on great bass grooves, so I may be better off with a box...
When using an active crossover you can easily change crossover frequencies.
The Supravox will work great in a 40 cm (16 inch) wide baffle from 300 Hz up.
The ScanSpeak woofer in sealed box crossed at 300 Hz, but at least 2nd order to prevent the cone break up from entering the picture.
The Sony D-23 is very versatile and you could experiment a lot.
The Supravox will work great in a 40 cm (16 inch) wide baffle from 300 Hz up.
The ScanSpeak woofer in sealed box crossed at 300 Hz, but at least 2nd order to prevent the cone break up from entering the picture.
The Sony D-23 is very versatile and you could experiment a lot.
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Indeed, the D-23 (Pioneer by the way, not Sony) is great for experimentation. I just need to learn a bit more about the interpretation of my measurements...
The BaSSline by Jeff Bagby is actually very similar to my idea. He uses the AE Lambda TD12H woofer. I heard many great things about this woofer, but I just don't seem to be able to get the same FR when I model it? Here is his simulation.
How could it possibly go that low?
The BaSSline by Jeff Bagby is actually very similar to my idea. He uses the AE Lambda TD12H woofer. I heard many great things about this woofer, but I just don't seem to be able to get the same FR when I model it? Here is his simulation.
How could it possibly go that low?
Apparently the Lambda woofers are in BR enclosures in that design.
BR gives a bit more bass, sealed most of the time sounds better with less coloration and that might be important for the woofer which will also reproduce mid bass.
BR gives a bit more bass, sealed most of the time sounds better with less coloration and that might be important for the woofer which will also reproduce mid bass.
I'd suggest to use a lower x-over frequency between the Supravox and a 30cm woofer. The Supravox should be quite a bit better than the large woofer for about an octave lower, and propably even more. And I'd use steeper filter slopes on the woofer/Supravox x-over, because the woofer will likely have resonances or other nasty features starting in the lower midrange.
Also, you could use a Linkwitz transform to use a relative small closed box and still get deep bass out of it. The Linkwitz transform is essentially an "undo" of the wrong tuning you get from a too small closed box, and then applies a new set of tuning parameters to your system. The Linkwitz transform is often included in active filters, either analog or digital.
Also, you could use a Linkwitz transform to use a relative small closed box and still get deep bass out of it. The Linkwitz transform is essentially an "undo" of the wrong tuning you get from a too small closed box, and then applies a new set of tuning parameters to your system. The Linkwitz transform is often included in active filters, either analog or digital.
Hey there, it has turned quiet in here, what happened to this promising project?
i would be interested to hear how it turned out. I am thinking about experimenting with an open baffle design, not unlike Troels OBL15 but with a supravox as mid.
cheers
J
i would be interested to hear how it turned out. I am thinking about experimenting with an open baffle design, not unlike Troels OBL15 but with a supravox as mid.
cheers
J
I have gone through many iterations of open baffle test designs by now... and am still experimenting. I ended up with a different midrange driver though, a vintage Stephens Trusonic 80FR (8" driver). I wouldn't necessarily say it sounds better to my ears than the Supravox driver, but it just fit better with my other drivers... because my open baffle grew up to be a 4-way!
The most tricky thing to me about open baffle speakers is getting some good low end (down to 30Hz or even lower). I ended up with an 18" subwoofer driver (McCauley 6174), lots of low end EQ, and a bigger amp. And so far, that works quite well.
I haven't really finished my experiments yet, but I will post here again once I have something that is somewhat finished...
Anyway, I wouldn't hesitate to experiment with the Supravox driver. Its sensitivity is great, midrange is very lively. But in my opinion it does need a tweeter and some extra support in the lower octaves, if you want a truly "full-range", as in full frequency range, OB speaker.
Apart from the many great studies that Siegfried Linkwitz posted online, I also recommend reading the english translation of Rudolf Finke's "Open Baffle" PDF. The latter is fairly easy to understand and helped me a lot to improve my OB designs. And if you understand German, read all his other pages, too 😉
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Hello drtebi, thanks for your reply.
a shame there is nor more info about how the original thread-speaker turned out.
does anyone have Frequency resp. of supravox drivers? i dont quite understand the graph on the manufacturer page, it states spl of around 65? for the 165GMF...😕
a shame there is nor more info about how the original thread-speaker turned out.
does anyone have Frequency resp. of supravox drivers? i dont quite understand the graph on the manufacturer page, it states spl of around 65? for the 165GMF...😕
You are right! I never noticed that the graph is somehow wrong. They are definitely not 65dB... they are quite sensitive, the specs say 96dB, and I would guess that is just about right.
I will probably sell my Supravox drivers soon, if you are interested, send me a PM.
I am using a vintage crossover, the Sony TA-D88, so my crossover points are somewhat limited. I am using the lowest possible one for the 18", which is 140Hz. It works out quite well, although the 18" needs quite a bit of boost on an open baffle. Once it has that though, pheeeehhhh, I love it 😉
Attached is a pic of the latest test baffle. Note the size of the iPhone 5 for comparison...
I am really happy about the narrow baffle. It sounds much better than the wider one (about 22") that I was using before this.
Anyway, this project is still in the making... and I am a bit busy remodeling the house right now. But once I make the final baffle, I will definitely post about it here.
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