Ahoy!
I am trying to design a 2-way speaker system. For the Tweeter I am considering:
Dayton Audio RST28A-4 - https://www.daytonaudio.com/product/1565/rst28a-4-1-1-8-reference-series-aluminum-dome-tweeter-4-ohm
And for the Woofer either:
1) 8" Dayton Audio DSA215-8 https://www.daytonaudio.com/product/1315/dsa215-8-8-designer-series-aluminum-cone-woofer-8-ohm
2) 10" Dayton Audio DSA270-8 - https://www.daytonaudio.com/product/1316/dsa270-8-10-designer-series-aluminum-cone-woofer-8-ohm
For my use case frequencies below 80Hz are not super important -- but could be nice to have.
With a sealed enclosure the F3 for the DA215-8 is at around 80Hz and for the DSA270-8 it is at around 60Hz.
I am having a hard time figuring out how to evaluate the performance at the higher frequencies. I think my crossover should be at around 2500Hz? Am I giving up midrange sound quality by using the 10" instead of the 8"? Or perhaps the only penalty I am paying is a larger box for the DSA270-8, but with a nice amount of bass extension as the payoff? The max SPL before exceeding xmax is about the same.
I have mostly messed around with subwoofer builds -- so I am pretty clueless about understanding how to evaluate woofers for a 2-way design.
The specs for the DSA270-8 say it has a usable range of 29-6000Hz. But the frequency response graphs look like the are already starting to get wonky by 2500Hz. How do I distinguish between 'usable' and 'sounds good'? I can't go too low on the crossover because then the RST28A won't be able to deliver.
This will be a biamped system using a minidsp 2x4 HD for the crossovers, eq, etc.
I am currently simulating using winISD, but willing to consider alternatives.
I am trying to design a 2-way speaker system. For the Tweeter I am considering:
Dayton Audio RST28A-4 - https://www.daytonaudio.com/product/1565/rst28a-4-1-1-8-reference-series-aluminum-dome-tweeter-4-ohm
And for the Woofer either:
1) 8" Dayton Audio DSA215-8 https://www.daytonaudio.com/product/1315/dsa215-8-8-designer-series-aluminum-cone-woofer-8-ohm
2) 10" Dayton Audio DSA270-8 - https://www.daytonaudio.com/product/1316/dsa270-8-10-designer-series-aluminum-cone-woofer-8-ohm
For my use case frequencies below 80Hz are not super important -- but could be nice to have.
With a sealed enclosure the F3 for the DA215-8 is at around 80Hz and for the DSA270-8 it is at around 60Hz.
I am having a hard time figuring out how to evaluate the performance at the higher frequencies. I think my crossover should be at around 2500Hz? Am I giving up midrange sound quality by using the 10" instead of the 8"? Or perhaps the only penalty I am paying is a larger box for the DSA270-8, but with a nice amount of bass extension as the payoff? The max SPL before exceeding xmax is about the same.
I have mostly messed around with subwoofer builds -- so I am pretty clueless about understanding how to evaluate woofers for a 2-way design.
The specs for the DSA270-8 say it has a usable range of 29-6000Hz. But the frequency response graphs look like the are already starting to get wonky by 2500Hz. How do I distinguish between 'usable' and 'sounds good'? I can't go too low on the crossover because then the RST28A won't be able to deliver.
This will be a biamped system using a minidsp 2x4 HD for the crossovers, eq, etc.
I am currently simulating using winISD, but willing to consider alternatives.
Use the 8”: it has a more linear response above 1kHz, both on and off axis.
For a 2-way I’d use the Scanspeak or Peerless ring-domes in one of augerpro’s (Brandon’s) waveguides.
For a 2-way I’d use the Scanspeak or Peerless ring-domes in one of augerpro’s (Brandon’s) waveguides.
D2604/833000
https://www.scan-speak.dk/product/d2604-833000/DX25BG60-04
Looking at the response curves for the 8" vs the 10" that certainly appears to be true. Especially the off axis response.
Is there some way to determine from the response curve where things are going to start getting ugly? For the DSA215-8, it looks to me like the first really big dip is around 3k.
https://www.daytonaudio.com/images/resources/295-530--dayton-audio-DSA215-8-specifications.pdf
So keeping the crossover point closer to 2500Hz 'seems good'. Is there anything else useful in the datasheet to help give a better answer than just looking at the response curve and making an educated guess? Or does it just come down to experience and experimentation at this point?
Along similar lines -- is there anything in the datasheets that makes the DS2604 clearly a better tweeter than the RST28A -- or is that also just a matter of experience. I know the scanspeak is well loved.
3.2 kHz doesn’t look good for the 8”; ideally you’d want a crossover an octave below that - 1.6 kHz, but it depends on the low-pass filter. Also ideally you would want as low a crossover as possible to lessen (vertical) combing between the tweeter and mid-bass.
If you are using a moderate-to-large elliptical waveguide it should easily allow a 1.6 kHz crossover.
data-sheet: Dayton tweeter isn’t as linear and while not on the data sheet it’s also known to have manufacturing issues unlike the previous production model for that same driver.
What you can’t see is that the profile of the fabric and doping of the diaphragm on the Scan in particular is more complex - and they are known for “squeezing” a bit more detail out of a driver. The venting on the Scan & Peerless might be a bit better than the Dayton as well with a little less air resistance, but I’m not sure about that with these particular tweeters.
If you are using a moderate-to-large elliptical waveguide it should easily allow a 1.6 kHz crossover.
data-sheet: Dayton tweeter isn’t as linear and while not on the data sheet it’s also known to have manufacturing issues unlike the previous production model for that same driver.
What you can’t see is that the profile of the fabric and doping of the diaphragm on the Scan in particular is more complex - and they are known for “squeezing” a bit more detail out of a driver. The venting on the Scan & Peerless might be a bit better than the Dayton as well with a little less air resistance, but I’m not sure about that with these particular tweeters.
Real-world measurement:
https://www.dibirama.altervista.org...n-audio-dsa215-8-woofer-8-8-ohm-160-wmax.html
1.6kHz seems about right; probably a narrow notch filter centered at 3.1 kHz as well.
https://www.dibirama.altervista.org...n-audio-dsa215-8-woofer-8-8-ohm-160-wmax.html
1.6kHz seems about right; probably a narrow notch filter centered at 3.1 kHz as well.
For a 2 way design, you want your directivity for your tweeter and woofer to "blend". This means crossing over before your woofer starts to seriously beam and rolloff off axis. If you cross too high, and the woofer is rolling off, you'll see a dip near the crossover point between woofer and tweeter which will get worse as you move further off axis. A smooth even power response is generally a design goal. How this will sound in your listening room I can't say.
if you are not worried about bass, then a 6.5" 2 way - is the best compromise. you get good response down to 80Hz sealed with most 6.5" ways and a higher crossover point reducing tweeter stress, assuming you are not planning on using a waveguide.
By choosing an 8" or 10" - something tells me you want more bass, or feel a bigger surface area will be better for upper bass / lower midrange.
if you are not worried about bass, then a 6.5" 2 way - is the best compromise. you get good response down to 80Hz sealed with most 6.5" ways and a higher crossover point reducing tweeter stress, assuming you are not planning on using a waveguide.
By choosing an 8" or 10" - something tells me you want more bass, or feel a bigger surface area will be better for upper bass / lower midrange.
I do have access to a 3D printer so I could 3D print a waveguide. I do not see one listed specifically for the DS2604/833000. Are the T/S parameters similar enough that I can use a design intended for one of the other speakscan tweeters? Or is that a bad idea?
You can try the waveguide for the Scanspeak 6600 dome. Should perform similarly, but I would do a test print and measure in-box before you spend a lot of money.
A waveguide is the way to go. With the miniDSP you can easily put in the shelf filter to flatten the 6 dB low frequency boost. Before you spend time printing a waveguide you should look at the Viston offerings as they are very reasonably priced. I use them with the high end KE 25 SC Visaton tweeter, but they will work with other 1" drivers. https://www.parts-express.com/search?keywords=visaton waveguid&order=relevance:desc
For 6.5" vs 8" the concern is more about max SPL.
Looking at the 6.5" DSA175-8 vs the 8" DSA215-8, the DSA175-8 would seem to have a lower F3, but at frequencies above 100Hz the 8" has a max SPL is that 5-6dB louder.
The primary use case for this speaker is for a vocal monitor wedge for practice space for a basement band. I don't need to achieve the same crazy high SPL of commercial monitor wedges (124-132dB). But the DSA175-8 seems to max out at around 100dB -- which seems a little underpowered. 106dB seems like it should have enough headroom to be loud enough without always pushing the system to the max.
Frequencies below 80Hz aren't that important because there will probably be an 80Hz highpass on the vocal mic anyway.
I did also consider using a coaxial pro woofer like the PCX12-8. That driver has much higher sensitivity and a max SPL closer to 115dB. But the xmax on those coaxial pro woofers seems to be tiny -- like 2mm. So I would need a high pass at 150Hz to avoid exceeding the xmax at those SPLs.
I am not opposed to using a waveguide -- but I do also want this project usable by Christmas -- so keeping things simple is good.
One solution I have considered is doing an MTM inspired design. Using two 6.5" woofers could give me more SPL while keeping the crossover frequency higher.
But, of course, MTM designs bring a bunch of other problems I don't know how to address into play.
In the end I guess my design requirements are:
1. sounds great on vocals
2. loud enough to be heard over the drums and guitar
3. small box size
4. 2-way
I was originally planning a 3-way design -- but then I got sticker shock when I saw how much the price of amplifiers has gone up since I last bought some.
I have decided to use the MiniDSP 2x4HD for active crossover, room correction, and to also hopefully EQ any feedback. Probably not a good choice for a mobile rig, but this will be setup in the practice space and not moved around -- so it just needs to sound good there. Also, if the box sounds terrible and I have to do a new design -- it is much easier to reprogram the MiniDSP than it is to try to reuse a passive crossover network.
So I am now considering two options:
1. 8" woofer and 1" tweeter using a waveguide
2. dual 6.5" woofers and a 1" tweeter with no waveguide.
Or perhaps I can find a single 6.5" woofer that is good in a sealed box down to 80Hz while also being able to output at 105dB without exceeding xmax?
Looking at the response graphs for the 6.5" DSA175-8 vs the 8" DS215-8, is there something I can see that will tell me if the DSA175-8 would actually have more appropriate directivity to match with the tweeter?
https://www.daytonaudio.com/images/resources/295-528--dayton-audio-DSA175-8-specifications.pdf
https://www.daytonaudio.com/images/resources/295-530--dayton-audio-DSA215-8-specifications.pdf
To my untrained eyes, it looks to me like the off axis response of the 6.5" DSA175-8 is worse between 2-3K. And also the 8" DSA215-8 would seem to have a flatter response between 1-2k. So, if I opt to use a 6.5" woofer -- the DSA175-8 does not look like a winner to me. But I don't actually know what I am doing.
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I like the ease of simply adding the Visatron WG 148R to my order. But how do I actually know if it is going to work with a particular tweeter. It seems like a lot of times even if the sound quality is going to be great -- I would still need to 3D print an adapter plate because the screw holes on the tweeter and the screw holes on the WG do not line up? Or I drill new holes in the tweeter flange?
Obviously I would like to just order a good sounding tweeter from parts express that works out of the box with the WG 148R and has a suitably low Fs. But it is less obvious how to comb through the 9 pages of search results for 1" dome tweeter to find a suitable match.
8” Elliptical looks about right.
https://www.somasonus.net/scanspeak-d3004-6600
Maybe accept the dip at 10-14kHz and try a 6.8uf cap in series and see what the resulting high-pass is like when modeled. Reverse phase for integration with mid bass.
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The Dayton Audio RST28F-4 (Fabric dome) works better than the RST28A in a waveguide. It works in the Visaton WG148 without any kind of adapter. In the waveguide it can crossover low enough to match an 8 inch woofer. (Probably around 1.4Khz but not sure if you would even need to go that low, but somewhere between 1.5Khz and 2Khz is likely, NOT 2.5Khz as you originally suggested. The main problem of an 8" two-way (and very difficult with a 10") has been hinted at above...beaming / directivity.)
Pair that with the new Signature Series SIG225-4. F3 of 70Hz in a 0.55cf sealed box.
Pair that with the new Signature Series SIG225-4. F3 of 70Hz in a 0.55cf sealed box.
might try this in white resin
https://www.pcbway.com/
another Chinese source for resin prints
https://www.wenext.com/3d-printing/sla
A more expensive but US source for SLS prints:
https://www.jawstec.com/
Then there is a “marketplace”:
https://craftcloud3d.com/?utm_campa...all3dp.com/2/best-cheap-3d-printing-services/
Generally I’d avoid FDM prints, but there are some out there getting high accuracy prints in a variety of materials from FDM.
https://www.pcbway.com/
another Chinese source for resin prints
https://www.wenext.com/3d-printing/sla
A more expensive but US source for SLS prints:
https://www.jawstec.com/
Then there is a “marketplace”:
https://craftcloud3d.com/?utm_campa...all3dp.com/2/best-cheap-3d-printing-services/
Generally I’d avoid FDM prints, but there are some out there getting high accuracy prints in a variety of materials from FDM.
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That sounds convenient. It looks like I do need to carefully remove the faceplate from the RST28F and attach the WG148 in its place?
Problem? Or benefit? This speaker will be used as a vocal floor monitor. I've noticed that many commercial monitor wedges have 12" and 15" woofers and speak of 50° horizontal and 90° vertical dispersion patterns. Seems like beaming can be beneficial if the aim is to direct the sound at a single performer and limit spill to keep the volume on stage down?
Clearly, putting a waveguide on the tweeter isn't going to affect the directivity of the woofer -- so I am assuming the goal is to make the tweeter more closely match the beaminess of the woofer? For someone standing directly in front of the speaker the difference should be minimal? but as you get more off axis it should help keep the sound more balanced -- especially near the crossover frequency where both drivers are contributing to the sound?
In an ideal world, would the diameter of the waveguide match the diameter of the woofer cone?
This is a nice driver. Looks like the 6.5" version can achieve the same SPL if I am willing accept an F3 of 100Hz. So I could choose between better off axis response or better bass extension.
What? An 8” wide waveguide with an 8” midbass? That’s just crazy! 😉
In truth though it’s more about the actual result, though the result is primarily a function of the diameter of the driver or waveguide ALONG WITH THE BAFFLE. “Deep” waveguides/horns or even drivers also substantively effect this.
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The tweeter that mates perfectly with the WG148 waveguide is the KE 25 SC tweeter. I have used this tweeter in many speakers and it has a very flat response and can achieve distortion figures of 0.1% at moderate listening levels. Mouser is selling it in the USA. Call to order and insist they wrap the tweeter box completely in bubble wrap or foam before dropping it in a box to ship it. If it ships bouncing around in an empty box, send it back as it will be junk at that point as the face plate will shift when dropped on it's side by UPS.
Here is a link to Mouser: https://www.mouser.com/ProductDetail/Visaton/KE-25-SC-8-Ohm?qs=VWNNG7jHlrIxfM3uThNIqQ==
There is a link to the datasheet on the Visaton site: https://www.visaton.de/en/products/drivers/dome-tweeters/ke-25-sc-8-ohm
Here is a link to Mouser: https://www.mouser.com/ProductDetail/Visaton/KE-25-SC-8-Ohm?qs=VWNNG7jHlrIxfM3uThNIqQ==
There is a link to the datasheet on the Visaton site: https://www.visaton.de/en/products/drivers/dome-tweeters/ke-25-sc-8-ohm
Hmmm...I thought so. I plan on a build with the RST28F-4 in the Visaton WG with the SIG180 woofer. I have read that the RST28F fits the waveguide and have seen and heard speaker with this tweeter and waveguide combination. The tweeter comes with a protective metal grill and a plastic phase shield under that. One post I read, the designer thought the grill was glued on but he said he just popped it off. Well...mine WAS glued on and I was able to get it off with a razorblade knife and pry it off with my Allen wrench that I had used to remove the screws in the faceplate. NOTE, this is necessary as the waveguide does NOT fit over the protective grill. I also cut the plastic phase shield off with my knife. On the second one I didn't and the waveguide WILL fit over the plastic phase shield. I have not used this combination yet, but I have used this waveguide and build an adapter using the baffle cutout to clamp the tweeter to the waveguide.
Faceplate removed...
Protective grill dome removed. Plastic phase shield (permanently) removed from one. Faceplates put back on...
DIY adapter to clamp tweeter to waveguide. The tweeter used below did not have a faceplate so I could just clamp them together. For the RST28 the faceplate covers the holes on the back of the waveguide so you'll have to drill holes in the faceplate or add some sort of adapter.
Having either wide or narrow dispersion can have their advantages and will be determined by the tweeter. The woofer will be omnidirectional at low frequencies and start to beam at some point. What you want to avoid is a directivity MISMATCH. You want the directivity to blend smoothly from the woofer to the tweeter. Smaller tweeters will have wider directivity.
yes.
Yes, if you are directly in front of the speaker AND CLOSE. But there will USUALLY be reflections (more specifically early reflections) and poor directivity will result in poor sound quality at the listening position.
From what I have read, yes, but I don't really know the details or caveats around that.
6.5" will give better directivity control and 8" will provide better bass extension. I tend to want to cross over to a subwoofer below 100Hz, thus I suggested the 8" knowing what your plans are, but crossing over at 100Hz should be okay.
The 8" will achieve higher SPL - even though they have basically the same sensitivity, the 8" will take more power and thus be able to go louder. However, knowing your plans I don't think that will matter at all because if you run them as loud as you can as close as you plan you will probably be deaf relatively soon.
There are always tradeoffs - nothing wrong with using the 8", but if it were me I'd go with the 6.5".