Never heard them but seem to be famous about the mid range quality ;-) I use the D54 without horn and that's already superb for my ears.
Yes the D54 in the Edgar Tractrix 500Hz horn produces a beautifully expressive and real sounding midrange.The closest sound to it is probably the vintage 15 inch Tannoys.That combination of power and energy but also sounds very relaxed,organic and warm.
Correct.
I dome mid is simply not the right choice in a party application
Many years ago Studio Sound published an article by Philip Newell on studio monitors called then Reflection Arts. Newell noted them ( in the 1980’s) that domes were smoother inside their spl range but horns ruled above that range.
Of course getting a horn to sound anything like a dome mid is an art form…Lol.
Btw have you looked at Eric Alexander’s Tektron high frequency arrangement.
He uses a pettle like cluster of dome tweeters (7 or more). The impact is far higher linearity and power handling such that they can operate down below 1000 hertz.
Half a dozen cheaper dome mids might be your answer then
Would a diy dome mid driver be admissible here?
I was thinking that if the back cup was removed from a compression driver the exposed diaphragm would make an intertwined experiment.
I have a number of Jbl compression drivers to evaluate if any one is interested.
I realise this might be a chicken (check-in in NZ ) stuck in your necks at the thought of compression drivers but thought it was worth calling out.
Great thread guys.
I was thinking that if the back cup was removed from a compression driver the exposed diaphragm would make an intertwined experiment.
I have a number of Jbl compression drivers to evaluate if any one is interested.
I realise this might be a chicken (check-in in NZ ) stuck in your necks at the thought of compression drivers but thought it was worth calling out.
Great thread guys.
Textreme (laminate carbon) is set to take over beryllium as the material of choice for drivers. I think SB will be working on a textreme dome mid before long.
Subjectively on hificompass they describe it was more forgiving.
Subjectively on hificompass they describe it was more forgiving.
I may get some M142T-6 for testing, but my expectations from a $3200 pair of mids are going to be strict.
The thing with carbon, fiberglass or kevlar composites is their mechanical performance and behavior being sensitive to the binding adhesive / agent as well as the mechanical interfacing of all said ingredients. If the "glue" that holds everything together is higher in proportion to the CF by volume, the composite becomes more like a hard plastic. IOW the mechanical properties of the composite is dictated by (among other things).by the dominating percentage of material its comprised of.
Lightly bound CF with minimal resin has a higher internal dampening factor, so a diaphragm made of this type of CF will exhibit smoother response with a broader breakup mode above the 1st diaphragm resonance mode.
In contrast, a greater percentage of resin by volume with CF yields mechanical properties similar to hard plastic / acrylic. This material composite used as a diaphragm will have a sharper upper breakup mode with a higher peak, as seen with other common, very rigid diaphragm constructions and composite materials.
Obviously, textreme isn't just simple woven CF and resin. Thats why its so suitable as a diaphragm material, due to the other details found with its construction. Its a pretty amazing substance which has its own sound signature.
Lightly bound CF with minimal resin has a higher internal dampening factor, so a diaphragm made of this type of CF will exhibit smoother response with a broader breakup mode above the 1st diaphragm resonance mode.
In contrast, a greater percentage of resin by volume with CF yields mechanical properties similar to hard plastic / acrylic. This material composite used as a diaphragm will have a sharper upper breakup mode with a higher peak, as seen with other common, very rigid diaphragm constructions and composite materials.
Obviously, textreme isn't just simple woven CF and resin. Thats why its so suitable as a diaphragm material, due to the other details found with its construction. Its a pretty amazing substance which has its own sound signature.
@macka I've dabbled with CDs being used as mid domes. There's alot of compromises to be made doing this unless you're willing to permanently ruin the driver's functionality as a CD. The phase plug must first be removed and a front mounting flange plate needs to be built with provisions for VC wires and terminals made. If you decide to try the conversion after all this doom and gloom prediction, the chamber will need a light weight, precisely even coating of dampening media. Something like silicone oil or PVA will work fine.
I bought a pair of PRV D3220PH along with titanium replacement diaphragms to try. They are relatively cheap at $90/pc and sound good as CDs, plus they have a smaller magnet to VC size ratio to keep the CTC spacing to the HF driver to a minimum. I don't have high hopes, but the price wasn't so high that it's no big loss if it doesn't work out.
I bought a pair of PRV D3220PH along with titanium replacement diaphragms to try. They are relatively cheap at $90/pc and sound good as CDs, plus they have a smaller magnet to VC size ratio to keep the CTC spacing to the HF driver to a minimum. I don't have high hopes, but the price wasn't so high that it's no big loss if it doesn't work out.
I don’t think so.
I was referring to removing the back cover which will expose the diaphragm.
All that needs to be done in measuring the resonance frequency. The throat can either to sealed or left open
I was referring to removing the back cover which will expose the diaphragm.
All that needs to be done in measuring the resonance frequency. The throat can either to sealed or left open
You won't achieve the best possible linearity and performance as a direct radiating dome driver if the phase plug is still in place, as it won't provide the necessary acoustic dampening of the rearward radiated energy of the dome.
I've tried just removing the CD back chamber and leaving the phase plug in place, both with open and chambered throat of varying volume. It doesn't sound good. Not anything close to a decent larger dome driver.
I know some of us have tried just pulling the rear chamber cup on a CD and facing it the other way, plus inverting the phase. It doesn't sound anything like a decent dome mid. There's multiple resonant peaks across the whole FR and not enough excursion capability due to the typical close diaphragm proximity to the phase plug.
I've tried just removing the CD back chamber and leaving the phase plug in place, both with open and chambered throat of varying volume. It doesn't sound good. Not anything close to a decent larger dome driver.
I know some of us have tried just pulling the rear chamber cup on a CD and facing it the other way, plus inverting the phase. It doesn't sound anything like a decent dome mid. There's multiple resonant peaks across the whole FR and not enough excursion capability due to the typical close diaphragm proximity to the phase plug.
In my view there are two issues with using CD' s inverted.
One is the suspension of the typical 3" diaphragm is usually quite stiff, leading to resonant frequencies around 900 Hz or higher, even for 3" diaphragms. The other is these diaphragms are much flatter than a typical 3" dome.
That being said, the thought of using a 3 or even 4" diaphragm has also crossed my mind more than once.
So, go for it, this is diy after all.
One is the suspension of the typical 3" diaphragm is usually quite stiff, leading to resonant frequencies around 900 Hz or higher, even for 3" diaphragms. The other is these diaphragms are much flatter than a typical 3" dome.
That being said, the thought of using a 3 or even 4" diaphragm has also crossed my mind more than once.
So, go for it, this is diy after all.
@Boden I agree with you. There are too many things which work against you repurposing a CD as a direct radiating dome. The PRV D3220PH has a low Fs around 400 hz, a reasonably compliant surround and adequate diaphragm clearance to the phase plug. The alternative soft suspension Ti replacement diaphragm brings Fs down even further. The phase plug has to go if one wanted to even entertain the notion of decent performance as a dome mid, as it creates all sorts of weird resonances shrouding the back of the diaphragm.
@macka It's not all hopeless. Just have to commit to potentially sacrificing a driver to make it work - something most of us don't want to do.
Using a 2" exit driver, its a matter of using a basic drill press with a 2" forester bit to drill open the pole piece. Next step would be chamfering the opening with a conical router bit, again with the drill press, keeping the speed at a slow rpm and feeding it very slowly by hand. You'd be drilling from the front side of the driver, phase plug down. A thicker plywood board with a hole cut into it large enough to suspend the phase plug away from the drill platform.
The phase plug on most CDs is either plastic or aluminum, so its easy to keep the VC gap clean with some blue tac or aluminum tape covering it. The greatest challenge is clamping the driver in place so it stays put, unless you want to risk holding it with your hands using heavy gloves for protection. It would be alot easier if you know someone with a Bridgeport milling machine, but most of us don't have that access to something that specialized.
The greatest dilemma doing all this is having to offer up a decent quality driver with decent performance on a WG used as a CD. Cheap drivers won't work as well just because they're already bad as a purpose intended CD. You should use a half way decent CD to start with, but that makes it even more of a sacrifice if it doesn't work out. You'll never know unless you try.
In my case, I have a half way decent $100 driver which could be of good use on a WG just the way it is. Thats alot of money to most of us. You'd have to be somewhat adventurous to try the conversion and risk the functional loss of a CD and putting the work into modifying it and possibly ending up with a paper weight. The PRV driver I have has a very good chance of working out well as a converted dome. A plus would be having the choice of 3 different domes, further adding to the potential success of this modification.
IMO, the outcome would need to be performance similar to a $500 Volt 3" mid dome to be worth the hassle and initial cost. I should probably start another thread for this to not derail this one. I haven't decided if its worth it to me, but the initial outlook is good based on what I've already observed.
Using a 2" exit driver, its a matter of using a basic drill press with a 2" forester bit to drill open the pole piece. Next step would be chamfering the opening with a conical router bit, again with the drill press, keeping the speed at a slow rpm and feeding it very slowly by hand. You'd be drilling from the front side of the driver, phase plug down. A thicker plywood board with a hole cut into it large enough to suspend the phase plug away from the drill platform.
The phase plug on most CDs is either plastic or aluminum, so its easy to keep the VC gap clean with some blue tac or aluminum tape covering it. The greatest challenge is clamping the driver in place so it stays put, unless you want to risk holding it with your hands using heavy gloves for protection. It would be alot easier if you know someone with a Bridgeport milling machine, but most of us don't have that access to something that specialized.
The greatest dilemma doing all this is having to offer up a decent quality driver with decent performance on a WG used as a CD. Cheap drivers won't work as well just because they're already bad as a purpose intended CD. You should use a half way decent CD to start with, but that makes it even more of a sacrifice if it doesn't work out. You'll never know unless you try.
In my case, I have a half way decent $100 driver which could be of good use on a WG just the way it is. Thats alot of money to most of us. You'd have to be somewhat adventurous to try the conversion and risk the functional loss of a CD and putting the work into modifying it and possibly ending up with a paper weight. The PRV driver I have has a very good chance of working out well as a converted dome. A plus would be having the choice of 3 different domes, further adding to the potential success of this modification.
IMO, the outcome would need to be performance similar to a $500 Volt 3" mid dome to be worth the hassle and initial cost. I should probably start another thread for this to not derail this one. I haven't decided if its worth it to me, but the initial outlook is good based on what I've already observed.
This is the advice I received when considering it briefly.
https://www.diyaudio.com/community/threads/compression-driver-as-midrange-dome.358132/
https://www.diyaudio.com/community/threads/compression-driver-as-midrange-dome.358132/
Here are the "famous" SBAcoustic SATORI MD60N-6 and their 2.5" dome...
T
T
@tubelectron Would it be a big hassle for you to remove the rear chamber and take some pictures? I'm sure all of us would love to see inside that chamber, which would answer a few questions we had about its dampening.
Yes @profiguy ! It seems quite easy to do : three Allen screws, apparently... I'll do it on Monday, take pictures of the details and post them here. 😉
T