I'm sure this has been discussed in the Mid Dome thread but that thing is long and goes off on tangents like crazy.
When I first started looking at speaker drivers I did come across this driver. My first thought was "this is a crazy response. I don't really understand how this could be useful in any way"
Well, a year later and I have started to understand the beauty of this gem. Can you really use it with these lower order filters? Does anyone have a distortion measurement they could share before I dive into this? I'm open to any kind of advice on how to best utilize this dome.
Backstory behind the system: The wife has requested a system for the kitchen and I am going to design it around this. I want to keep the costs down so I'm going to use Hivi Q2R and a Dayton DA175 woofer. I'll be using lower order filters
When I first started looking at speaker drivers I did come across this driver. My first thought was "this is a crazy response. I don't really understand how this could be useful in any way"
Well, a year later and I have started to understand the beauty of this gem. Can you really use it with these lower order filters? Does anyone have a distortion measurement they could share before I dive into this? I'm open to any kind of advice on how to best utilize this dome.
That probably would be fine. Hificompass tested this driver with a 2nd order 500 Hz high-pass filter in place, similar to yours.
One thing that might be questionable is the harmonic distortion "tumult" between 4 and 5 kHz. When multiple harmonic distortion peaks appear in the same frequency range, it usually doesn't mean much good. How much of this would be audible (partly with your minimalist crossover, although the THD is not high) is a good question.
https://hificompass.com/en/speakers/measurements/scan-speak/scanspeak-d7608/920010
One thing that might be questionable is the harmonic distortion "tumult" between 4 and 5 kHz. When multiple harmonic distortion peaks appear in the same frequency range, it usually doesn't mean much good. How much of this would be audible (partly with your minimalist crossover, although the THD is not high) is a good question.
https://hificompass.com/en/speakers/measurements/scan-speak/scanspeak-d7608/920010
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There's some information on the dome midrange thread, but as you say that's very long and diverse.
What I would like to see is this dome mated with a mid-bass of equal sensitivity. The data says 92db. It should be possible to find an 8" or 10" that's at least 90db.
What I would like to see is this dome mated with a mid-bass of equal sensitivity. The data says 92db. It should be possible to find an 8" or 10" that's at least 90db.
Not an easy task if you consider in a typical baffle step loss and if you want any meaningful deep bass from the speaker.
Some examples of more sensitive mid-bass units with lower F3 in a sealed box
10”
SB SB26SFCL38-4 91db 4 ohms, paper £73
Visaton W250S 90db 4ohms, £82
Monacor SB252E 94db, £70
8”
Scanspeak 22W4534 92.5db glass fibre F3=62hz £110
Scanspeak 22W8534, 89db glass fibre F3= 56hz
SB SB20PFC 90.5db 8 ohm, paper F3=65hz £43
Monacor SPH220HQ 8 ohm, 90db paper F3=54hz £106
SEAS CA22RNX 89.5db, F3=53hz £118
Monacor SPM205-8 8 ohm paper, 89db F3=48hx £37
10”
SB SB26SFCL38-4 91db 4 ohms, paper £73
Visaton W250S 90db 4ohms, £82
Monacor SB252E 94db, £70
8”
Scanspeak 22W4534 92.5db glass fibre F3=62hz £110
Scanspeak 22W8534, 89db glass fibre F3= 56hz
SB SB20PFC 90.5db 8 ohm, paper F3=65hz £43
Monacor SPH220HQ 8 ohm, 90db paper F3=54hz £106
SEAS CA22RNX 89.5db, F3=53hz £118
Monacor SPM205-8 8 ohm paper, 89db F3=48hx £37
Okay, but how much sensitivity will remain if you subtract about 3-6 dB from them because of typical baffle step loss?
It seems the thread start sidetracking...
It seems the thread start sidetracking...
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According to 3rd party measurements it reaches 92 dB between 1-2 kHz. Similar like in the Hificompass measurements.
https://www.dibirama.it/home-page/m...-d7608-920010-mid-range-3-8-ohm-160-wmax.html
https://www.dibirama.it/home-page/m...-d7608-920010-mid-range-3-8-ohm-160-wmax.html
Stat hounds in the weeds here splitting stalks, let’s come down off our baffle steps and bring it back round to dome mids?
The revelator mid-woofer would be ideal here but is more than what I want to spend in my kitchen (wife might say otherwise hut what she doesn't know....)
Right, this is what I see. I really wonder what would happen if you ran it 1st order bandpass. Would it survive?....
@Bmsluite If the D7608 (or any other mid for that matter) is mated with an equally voltage sensitive woofer, it would more than likely need to be padded down to get a flat summing or slightly falling FR towards the top end. Its common to mate lower sensitivity mids with slightly higher sensitivity woofers and tweeters (to a point). The reason for this is how the mids will sum in amplitude with the overlapping response of other drivers along with the bandpass gain of the filters on the mid itself. This often adds up to 3 - 4 dB of pad on the mid compared to the woofer after BSC has been factored in. With BSC, that can equate to another 2 - 3 dB less amplitude needed from the mid. Unless you like absolutely flat FR, there's little reason to use a mid with equal voltage sensitivity as the woofer.
You're welcome to chime in on the dome mid thread about this.
You're welcome to chime in on the dome mid thread about this.
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Electrically, yes. Mechanically it would be straining over 100 dB levels. I've pushed that dome past 70W (with a proper chamber) for short periods of time without issues. Its pretty stout that way. I've also used it as a filler driver a la B&O, which works very well if the level isn't pushed to hard. You only have 1mm p-p to work with, but practically that number is a little higher due to magnetic gap flux geometry.
That FR is without a chamber. It really needs one to perform well and be crossed down to 500 - 600 hz. With chamber, it levels out to 91 dB average. Dont bother trying to run this mid OB. It won't sound right due to the dampening it has behind the motor. Dont be tempted to remove the felt. If you do, it will worsen the FR from the front side. Its not designed for that. Also, without the felt, you'll end up with an additional small peak just above 1k from the VC gap resonance that appears. The intended way SS designed this dome to operate is with the felt and in a chamber of less than 500 ml.
I did see a bit of the thread where someone was making a back cup for it. I succeeded in making one of the these to tame the GRS planar mid. I have 3 large 3d printers and lighting fast CAD skills so the sky is the limit as far as how many styles I can test. Whatever I come up with, I will make the file public domain.
@Bmsluite I already designed a chamber for it and had someone convert the drawing to STL. However, I had alot of bad crap interfering with progress on this in the last few months, keeping me from finalizing the design, specifically having the mains panel fail on our house, also taking out our entire central AC system with it.
Before the power finally failed, it fluctuated to the point it messed up all of my 3d print attempts on the chamber. Ill be trying again soon to get a decent pair of chambers done based on my design.
The main reason people don't have much success with the SS mid is in fact the chamber (or lack thereof). Once you have that, it transforms the mid into a completely different animal, way better than any other mid dome I've heard under $150. Of course you have to work with its strengths and avoid using it in the range where it doesn't play well. 600 - 3.5k is totally doable with 2nd order filters. Without the chamber, you lose the lower mid output, which also negatively effects the rest of the range.
Before the power finally failed, it fluctuated to the point it messed up all of my 3d print attempts on the chamber. Ill be trying again soon to get a decent pair of chambers done based on my design.
The main reason people don't have much success with the SS mid is in fact the chamber (or lack thereof). Once you have that, it transforms the mid into a completely different animal, way better than any other mid dome I've heard under $150. Of course you have to work with its strengths and avoid using it in the range where it doesn't play well. 600 - 3.5k is totally doable with 2nd order filters. Without the chamber, you lose the lower mid output, which also negatively effects the rest of the range.
Sorry to hear about your house. That really sucks.
I can print it out for you if you need it to keep going. I have like 80 rolls of filament. All different kinds for different things. I get rolls in bulk to they only cost me like $6 for regular stuff like PETG.
@Bmsluite The devil is in the details with the rear chamber. Its not just a simple cup on the back of the magnet. There are a few things to consider with the way SS has applied felt in an attempt to aperiodically dampen the VC gap resonance. The chamber volume must react against this resonance which normally occurs just above 1k. This is actually a common issue with most dome drivers that have wide VC gaps. Morel and Dynaudio have this issue with many of their dome drivers.
Regarding the chamber printing, the infill ratios and filament material need optimization to get a rigid and stable wall that will resist sagging and warping without much fussing with settings or supports. While print time is a secondary concern, I wanted to keep the design simple and basic to work well on other brands of printers with various types of filament.
My design incorporates a toroidal shape at the end to reduce standing waves and reflections without the need of excess dampening. This is to attempt preserving as much lower mid output sensitivity as possible while lowering Qtc and controlling the secondary peak.
Regarding the chamber printing, the infill ratios and filament material need optimization to get a rigid and stable wall that will resist sagging and warping without much fussing with settings or supports. While print time is a secondary concern, I wanted to keep the design simple and basic to work well on other brands of printers with various types of filament.
My design incorporates a toroidal shape at the end to reduce standing waves and reflections without the need of excess dampening. This is to attempt preserving as much lower mid output sensitivity as possible while lowering Qtc and controlling the secondary peak.
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This is a double edge sword. You actually do not want that. I thought the same thing when I started designing and testing things for audio with filaments. If you go too stiff you end up creating a high frequency resonance in the part itself. Everything resonantes. If you want stiff, just use ABS-GF. You're not going to want to do that. Creality PETG is about as a dead a material as I have found. When I need added stiffness I go to Tinmorry PETG-CF.
I have tested the following filaments:
PLA - rings like crazy
PETG - Some brands are good, some brands ring terribly
PETG-CF - Fantastic, all of it
PA6 - Pretty good but expensive and not worth the cost over PETG
PA12- Same as above
PA612-CF - Crazy Rigid but does ring. It rings in a softer way though. Sort of like a paper cone resonance. Very strange stuff
PC - This stuff is good. Its not easy to print but its even better than PETG and its virtually indisctructible
PC-CF - Same as the nylon CF
HIPS - Its ok, but its a wierd filament
PP - This is what your car bumper and your milk jug are made out of. Its really soft but its not elastic. Useful for mounting points you want to isolate from other resonances
ASA - Very stiff and rings like crazy
ABS - Sort of like ASA but doesn't ring as bad. Still not good
TPU - Like PP but stretchy. Good for making gasket but still better off laser cutting a closed cell foam gasket
I run an engineering fab shop so I get to use all the different filaments in different applications. Of course, I then try to apply them to audio.
I used a bunch of spikes and some wool for the planar mid. That ended up working better than any circular shape. I tired 14 other shapes and styles. It just smashes the wave wave in all directions through the wool. The energy is still there but it gets dispersed throughout a huge range of frequency and damped. It calmed down the planar mid enough that I could actually use it then.