It is a weird driver, gotta make your own chamber for it, seems like off axis breaks away really early at like 1.5khz?
I wouldn't pair it with a big faceplate tweeter or as high of a xover point. I'd pick a smaller overall sized tweeter to get it closer to the dome. All in all this is probably the last dome I would buy if I were making a three way with a dome mid. I'm mostly just baffled it doesn't come with it's own chamber.
I wouldn't pair it with a big faceplate tweeter or as high of a xover point. I'd pick a smaller overall sized tweeter to get it closer to the dome. All in all this is probably the last dome I would buy if I were making a three way with a dome mid. I'm mostly just baffled it doesn't come with it's own chamber.
Yes…..that’s precisely what dome mids are good at…..excellent mix monitors for identifying poor mic placement phase issues or when you’re pushing eQ or compression too hard on a source. But as a listening playback for enjoyment device?…..not so much…..the pokey nature brings the passband too front and center and makes the spatial image too unbalanced. Back in the early days as an assistant, I can still hear a visiting engineer shout….” Hey get me the pokey boxes please” in a distinct English accent……no names to protect their innocence LOL. Great driver for center channel speakers though……really locks dialogue to the image and intelligibility is fantastic. I don’t use dome mid three ways anymore in the control room as a coax driver does just as well in the same regard in a smaller box. Even a little full range mix cube can do the same job. Power handling isn’t as good mind you but you don’t need much volume to bring a phase issue into the light.
This is why when you see images of studio consoles taken during actual sessions and not staged photos, you’ll see three or so sets of monitors on the bridge…..each with a purpose. If you enjoy the sound of loud high precision monitors, go ahead and build it as we each have our own taste or preference when it comes to playback. Me….after decades of tuning in to phase anomalies, I much prefer the mash up of a good two ways anymore these days as most recordings fail the three way test miserably…..and the trend today is far worse.
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@Bmsluite Those fillament characteristics aren't going to be an issue if you choose the correct densities and geometry/shape of the chamber. We're talking about a small diameter, less than 4 inches and a wall thickness of about 1/4 inch. You can put a few hundred pounds on top of an average grade PLA printed chamber and it would survive just fine. I haven't noticed any noteworthy ringing with even thinner wall PLA printed chambers I've done on similar sized drivers. If you look at the older Vifa, Seas and Peerless drivers, they all had much thinner, more resonant chambers and although they were on the skimpy side, they didn't cause any significant issues with driver FR or THD. Erring on the side of caution, I'd always choose fiber loaded ABS, as it has a proven track record.
As far as the chamber geometry goes, a properly dampened circular chamber won't be a problem. Seas and Audax use a toroidal terminated chamber which deals with the majority of standing wave issue with the mean diameter WL being suppressed via the interrupted primary diameter. It also forms a short TL with this shape. All of the tweeters and mids using a similar shape of chamber have zero issues with standing waves or resonances, given the dampening media is suitable for the bandwidth of frequencies radiated from the back of the diaphragm. An excellent example of the toroidal chamber is the Seas T35-C002, which happens to be dampened with only a rolled up piece of wool felt. The Audax TW025A28 is another tweeter with this shape of chamber and has ZERO dampening media, yet its one of the finest 25mm metal domes I've listened to. Same goes for the T35-C002.
You're welcome to experiment with elaborate shapes of chambees on the D7608, but i can save you the hassle after having been there and done that myself. There's no significant benefit to using a TL shaped chamber on this mid. You alsp don't want it larger than 500 ml, otherwise you sacrifice lower mid output and sensitivity (what you're trying to preserve to begin with on a driver with 1mm p-p xmax).
I sincerely can appreciate your engineering skills, but I can honestly say I've tried all of the common tricks available on the D7608 rear chamber design, including tapered TLs. You're of course welcome to try yourself but I'm just being upfront, saying it won't yield anything ground breaking in trying to extract anymore performance from the D7608.
As far as the chamber geometry goes, a properly dampened circular chamber won't be a problem. Seas and Audax use a toroidal terminated chamber which deals with the majority of standing wave issue with the mean diameter WL being suppressed via the interrupted primary diameter. It also forms a short TL with this shape. All of the tweeters and mids using a similar shape of chamber have zero issues with standing waves or resonances, given the dampening media is suitable for the bandwidth of frequencies radiated from the back of the diaphragm. An excellent example of the toroidal chamber is the Seas T35-C002, which happens to be dampened with only a rolled up piece of wool felt. The Audax TW025A28 is another tweeter with this shape of chamber and has ZERO dampening media, yet its one of the finest 25mm metal domes I've listened to. Same goes for the T35-C002.
You're welcome to experiment with elaborate shapes of chambees on the D7608, but i can save you the hassle after having been there and done that myself. There's no significant benefit to using a TL shaped chamber on this mid. You alsp don't want it larger than 500 ml, otherwise you sacrifice lower mid output and sensitivity (what you're trying to preserve to begin with on a driver with 1mm p-p xmax).
I sincerely can appreciate your engineering skills, but I can honestly say I've tried all of the common tricks available on the D7608 rear chamber design, including tapered TLs. You're of course welcome to try yourself but I'm just being upfront, saying it won't yield anything ground breaking in trying to extract anymore performance from the D7608.
@mayhem13 The pokey sound you describe is simply a change in near to farfield balance. A good 3 way designed with some directivity control is significantly better in almost every way than a 2 way system. I believe alot of people are just used to the typical sound of a cookie cutter 2 way and are willing to put up with its limitations being a familiar sound.
If you apply some careful thought into designing a 3 way with or without a large dome mid, it will easily surpass a decent 2 way in almost every aspect. The near to farfield transition of most typical large 3 ways is less than optimal. That's simply due to corners being cut in the crossover and the chosen drivers, which usually lack the bandwidth capability to fully and cleanly overlap the neighboring driver. Add to that steep filters, then you have the issue of abrupt acoustic (phase) transition between drivers. The audible effects of this jump are worsened by sudden directivity changes, primarily between a larger woofer and mid. A larger baffle will also worsen the problem.
Some ways around this sudden jump in directivity and phase is the use of one or more of the following...
Large 3 way monitors like most ATCs with large woofers and 3 inch mid domes have too low of an xover point between LF and mid. This is audible when increasing the listening distance as the woofer starts beaming before the wider radiating mid takes over. The same may also happen between the mid and the tweeter.
Most 2 ways have the woofer transition to the tweeter well past the woofer break up point. Not only do you now have audible cone breakup to contend with, but also the directivity and phase jump of the wider radiating tweeter taking over. The known solution to this is running a tweeter WG, which also can be applied to the mid on a 3 way.
Properly designed 3 ways have more advantages and usually perform better than most 2 ways. Its mainly the commercial 3 way designs that give the decent ones a bad name.
Every design has compromises that need to be dealt with. You just have to choose what works best for your situation. Not all 3 way speakers have issues with directivity jump between woofer and mid, just as most 2 ways have between woofer and tweeter.
If you apply some careful thought into designing a 3 way with or without a large dome mid, it will easily surpass a decent 2 way in almost every aspect. The near to farfield transition of most typical large 3 ways is less than optimal. That's simply due to corners being cut in the crossover and the chosen drivers, which usually lack the bandwidth capability to fully and cleanly overlap the neighboring driver. Add to that steep filters, then you have the issue of abrupt acoustic (phase) transition between drivers. The audible effects of this jump are worsened by sudden directivity changes, primarily between a larger woofer and mid. A larger baffle will also worsen the problem.
Some ways around this sudden jump in directivity and phase is the use of one or more of the following...
- building a 4 way instead
- midrange WG
- multiple smaller LF drivers
- more suitable xover points
- narrower baffle width
Large 3 way monitors like most ATCs with large woofers and 3 inch mid domes have too low of an xover point between LF and mid. This is audible when increasing the listening distance as the woofer starts beaming before the wider radiating mid takes over. The same may also happen between the mid and the tweeter.
Most 2 ways have the woofer transition to the tweeter well past the woofer break up point. Not only do you now have audible cone breakup to contend with, but also the directivity and phase jump of the wider radiating tweeter taking over. The known solution to this is running a tweeter WG, which also can be applied to the mid on a 3 way.
Properly designed 3 ways have more advantages and usually perform better than most 2 ways. Its mainly the commercial 3 way designs that give the decent ones a bad name.
Every design has compromises that need to be dealt with. You just have to choose what works best for your situation. Not all 3 way speakers have issues with directivity jump between woofer and mid, just as most 2 ways have between woofer and tweeter.
This Peerless chamber is pretty clever I think. It has all the characteristics you are referencing. I will probably copy this and try it first. Easier to model than you'd think. Just use circular pattern tool
You'll see that that the chamber did boost the tweeter's lower frequency response significantly. I feel this shape/design will be a good starting point. Probably just do various on the radii of the curves. The lowest radius is quite sharp which is interesting to me.
I very much appreciate this bit of information as figuring out volume would have been its own adventure unto itself.
I'll just try a couple in comparison with yours. If I don't get anywhere with the first few I'll probably throw in the towel. I went way too far with the last build. I printed at least 25 horns before giving up and doing waveguides where I modelled, printed, and tested another 15 shapes. Then I printed like 30 different port stands. Too much.... It did turn out incredible though.
I agree with this wholeheartedly. I cannot go back to 2 ways. Its anathema to me at this point.
I know alot of people wonder why SS didn't include a chamber for the D7608. One of the main reasons was the driver being employed in some OEM designs. These had their own proprietary chambers, some of which integrated with the main enclosure.
Another reason for not including a chamber with the D7608 was how SS designed the mounting flange. This also required access to the rear motor for integration into the enclosure and mounting the driver.
When the D7608 came out under a different part number, there were 2 different versions with their own motor dampening applied. Having a detached chamber allowed tuning the mid for integration with different woofers along with their own baffle spacing and the consequential varying of acoustic centers.
Another reason for not including a chamber with the D7608 was how SS designed the mounting flange. This also required access to the rear motor for integration into the enclosure and mounting the driver.
When the D7608 came out under a different part number, there were 2 different versions with their own motor dampening applied. Having a detached chamber allowed tuning the mid for integration with different woofers along with their own baffle spacing and the consequential varying of acoustic centers.
What damping materials have you tried? I honestly haven't success with any damping material in rear chambers outside of the R14 rockwool. Seems most material just makes the chamber act as if it were larger. They don't seem to have much effect on actually dispersing the tones unless you mechanically disperse them which is what I did with the spikes.
Someone recomended magic eraser to me once and I did test that. Very strange result since it made the chamber non effective. It was as if I just filled it with in. You can still blow through magic eraser so it isn't closed cell. Just might be too dense
Rockwool is one of the effective dampening materials if its non roving. Sheeps wool is also good due to directional fibers. It needs to be installed with the fibers running front to back. Magic eraser doesn't work for me in most cases for absorption, but it helps with diffusion of higher frequencies through itself. Sheeps wool is my go to dampening material when filling an air space with it.
The white dacron fiber fill and magic eraser tend to reduce volume more than dampening the high air pressure zones, so when filling the enclosure with it, you tend to see an elevation in Fs.
The white dacron fiber fill and magic eraser tend to reduce volume more than dampening the high air pressure zones, so when filling the enclosure with it, you tend to see an elevation in Fs.
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