I have been experimenting and got some clarity on a problem that affects others here.
A half dozen pages or so back a few members posted about using Exciters that have the plastic stabiliser legs on them , They didnt like the feet and cut them off.
See photo attached below of a DAEX30HESF-4 , It has no stabiliser legs and i encountered serious issues with them at first.
They are rated at 40 watts / 4 Ohms however when i fed them with 40 watts they overheated , just by feel i think they were about 65 Celcius and because of the heat , the diaphragm got soft and the exciter drooped downwards causing the coil to chafe on the magnet , when the exciter is drooped down like that it rattles and resonates terribly , before you ask , Yes i supported the wires to take weight off the exciter.
My fix for these was to fit mounting hardware and a wooden spine , see pic below.
I think if i had chosen exciters with the stabiliser legs i wouldn't have had this problem as the legs prevent the droop i encountered.
If i use a single flat panel again i will use the exciters with stabiliser legs , i can see the need for them now.
I am sure Dayton are aware of this heating issue and thats probably why they brought out the range with stabiliser legs.
I , like many others , have had issues with the VHB tape not sticking , I am using 3mm laminex MDF panels and all the exciters i tested fell off within minutes , i even tried putting a coat of superglue on the MDF , let it dry and then stuck a fresh exciter on but it still wouldn't stay stuck.
I tested some Bullfrog quad exciters and they also didn't stick , maybe they stick just fine to other materials but not for me.
I think i would have serious issues attempting to use superglue to fasten a bullfrog quad to any panel because the glue might start to go off before i finished applying the last of it , maybe a different type of adhesive could work on those.
Its a work in progress.
In the above pic , the panels are 600 x 970 mm , i fastened one exciter on the 2/5 th position , and the second one i held on by hand , moving it around the panel while i played some high volume Double Bass , Cello , Drums and guitar music until i found the richest , warmest sounding spot , just a 2 inch movement made a big difference.
A half dozen pages or so back a few members posted about using Exciters that have the plastic stabiliser legs on them , They didnt like the feet and cut them off.
See photo attached below of a DAEX30HESF-4 , It has no stabiliser legs and i encountered serious issues with them at first.
They are rated at 40 watts / 4 Ohms however when i fed them with 40 watts they overheated , just by feel i think they were about 65 Celcius and because of the heat , the diaphragm got soft and the exciter drooped downwards causing the coil to chafe on the magnet , when the exciter is drooped down like that it rattles and resonates terribly , before you ask , Yes i supported the wires to take weight off the exciter.
My fix for these was to fit mounting hardware and a wooden spine , see pic below.
I think if i had chosen exciters with the stabiliser legs i wouldn't have had this problem as the legs prevent the droop i encountered.
If i use a single flat panel again i will use the exciters with stabiliser legs , i can see the need for them now.
I am sure Dayton are aware of this heating issue and thats probably why they brought out the range with stabiliser legs.
I , like many others , have had issues with the VHB tape not sticking , I am using 3mm laminex MDF panels and all the exciters i tested fell off within minutes , i even tried putting a coat of superglue on the MDF , let it dry and then stuck a fresh exciter on but it still wouldn't stay stuck.
I tested some Bullfrog quad exciters and they also didn't stick , maybe they stick just fine to other materials but not for me.
I think i would have serious issues attempting to use superglue to fasten a bullfrog quad to any panel because the glue might start to go off before i finished applying the last of it , maybe a different type of adhesive could work on those.
Its a work in progress.
In the above pic , the panels are 600 x 970 mm , i fastened one exciter on the 2/5 th position , and the second one i held on by hand , moving it around the panel while i played some high volume Double Bass , Cello , Drums and guitar music until i found the richest , warmest sounding spot , just a 2 inch movement made a big difference.
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bdjohns,
First I should clarify, because I forgot to in my initial post, that the frequency responses I originally posted were both made with the same volume setting on the amp, and gave virtually the same average SPL. The curves were manually offset several dB only for clarity, as they were otherwise on top of each other.
But you raise a good question. And the answer is that the distortion for 1 and 2 exciters at the sound level I was using was virtually identical. Today I did a few more measurements, cranking up the volume to see if there was a difference at higher volumes. My thought was that the two exciter version might have lower distortion at high volumes, but it was not the case, at least not at the volumes that I was permited to use before protests from my wife!
Below are the total harmonic distortion results for both 1 exciter (dashed) and 2 exciters (solid), a the loudest volume I was allowed to use. No real difference I would say.
Now here is a question for you all. As in this case, I have found that whenever I add a second exciter in series with the first, and set the volume control on my amp at the same level, the SPL is virtually the same for both 1 and 2 exciters. Is that what should be expected? My thinking would be that the additional resistance should actually reduce the total output, as Power=V^2/R. But what "should" happen to SPL with the addition of a second exciter (in series) with the same volume setting on the amp (ignoring any effect of constructive or destructive interference)?
Eric
Ears are the ultimate measure but not everyone can determine what they are hearing actually sounds good. Being an audiophile for over 40 years I have learned that what one hears is mainly based off of "EXPERIENCE". Sure there are people that actually have better hearing then others but to process what ones heard needs experience. The more experience the better one can process the information one is hearing. For example if you have never heard even a decent pair of stereo speakers then you would think everything sounds good which is why a lot of kids now days think there blue tooth speaker is the best sounding speakers in the world. lol When someone tells me that it sounds good my first reply is compared to what? The same way hand to eye cordination can be improved so can what one hears. Now are there some people who have a lot of experience and good hearing but cant differentiate between the two sources? Sure there are as there is always opposite ends of the spectrum.
Very cool
It's amazing the sound I get on the soft case alone.
not great, but definitely does the trick.
better than a big amp for portable practice
I just ordered two 6"x8" 1/8th inch thick bamboo kitchen cutting boards with rounded edges to try from amazon
maybe I'll VHB some 0.5mm carbon fiber onto it for some low end
It's amazing the sound I get on the soft case alone.
not great, but definitely does the trick.
better than a big amp for portable practice
I just ordered two 6"x8" 1/8th inch thick bamboo kitchen cutting boards with rounded edges to try from amazon
maybe I'll VHB some 0.5mm carbon fiber onto it for some low end
Earborne,
Nice solution. I've never seen a mount like that before. It should indeed support the exciter, and give you the ability to fine tune the location of the exciter relative to the panel, to avoid distorting the surround. As long as the mounting hardware it self doesn't rattle, I think I like it.
Eric
Nothing should be touching the panel diaphragm except for the exciters voice coil.
The legs hinder vibrations and act like damping since its touching the panel diaphragm. If people who built the exciters new what they were doing they would of REVERSED the legs so that the legs stick to the spine for support instead of the diaphragm.
Adhesive that sticks well is 2 part epoxy adhesive.
The DAEX30HESF-4 you mounted it correctly as you mount it to the spine and not the diaphragm.
More and more I find myself responding to different DMLs as I would respond to violin player playing the same music on two different violins.
This experience is probably not original to me.
In their essential character and emotional conveyance DMLs seem to me more like instruments than "loudspeakers".
Yep...I have tinnitus, but I can still pick up nuances in output that others miss.
Critical listening requires many hours of practice
In this case I trust Eric can spot the difference between the two outputs
Eucy
Yes i agree , The Bullfrog quads were damped , definitely not as sharp or clean due to the legs as what the DAEX30HESF-4 were , and the VHB tape failed within a few minutes so i need to go back to the drawing board and engineer a better approach from scratch.
Of the pair of panels i made , one is crystal clear perfection but the other has little bit of misalignment from my mounting screws being slightly off center and it rattles like a dancing skeleton at some frequencies (drum kick) so i need to tweak the adjustment of the M4 locknuts , i shouldnt have to stuff around so much to get a workable product so its quite disappointing.
I wonder if Dayton would consider thickening the end of the voice coil to give a bigger bond area ?
This is to be expected. Those magnets are way too heavy to be supported by flimsy little plastic feet and DS tape alone.
You will also notice that the 30HESF-4 has an M6 hole on the magnet, whereas the lighter drivers only have M3 holes. But the flanges on its sides can also be used for mounting to a brace exactly as you have done.
The wattage is only an indication of power handling, and is normally tested and then rated with low crest-factor white noise. Different kinds of music have different crest factors. Highly compressed, low crest-factor music program might blow your driver at 60W, whereas other, less compressed music, with a higher crest factor might be fine even over 80W. I would be very surprised if a 40W amplifier blows a 40W driver, or even heats it up significantly.
Maybe the rivers heated up because the coils were rubbing in the pole gap??
The stabiliser legs are only for units with smaller magnets. Those legs will not support larger magnets.
MDF has a porous surface. You'd have to seal it first before sticking DS tape or superglue to it.
https://www.diyaudio.com/community/...s-as-a-full-range-speaker.272576/post-7269780
Those units with supporting legs are designed to be used with supporting legs unless you support the magnet in some other way. The legs themselves make no difference to the sound. But I tend to cut them off anyway because I can situate multiple drivers closer together and then support all the drivers on a single brace-plate.
Anything touching the panel other then the exciters voice coil will change the sound. Just touching/holding the panel with your fingers will change the sound. Anything touching the panel will add weight to the panel and also act as a damping factor.
Its no different then adding any type of weight to a conventional cones diaphragm will change the sound.
Now I am not saying adding weight will make it worse or better but it will NOT sound the same.
Its no different then adding any type of weight to a conventional cones diaphragm will change the sound.
Now I am not saying adding weight will make it worse or better but it will NOT sound the same.
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More thickness equals more weight which means something will change be it sensitivity, frequency response etc.
Hello Eric
It probably means it is not related to the 1 or 2 exciter cases but to REW or the measurement set up (distance, reflections...). It is the difficulty of measurements in room and of the use of REW where the treatment are not fully explained.
Christian
Hello Eric
Let me try...
Same SPL in both cases is what I expect and also what I had in my experiment. The 2 exciters are in series so for a given amp volume adjustment the current flowing is divided by 2, the force applied to the panel by each exciter also (F = Bl.I), the total force remains the same, SPL also. The force remaining the same, as the SPL, the displacements are the same (or close) so the distortion is not modified.
The overall power capability is increase has you have 2 exciters (each voice coil being able to resist to its own power).
More funny, the total electrical power coming from the amplifier is reduced which make sens as having 2 magnetic circuit, there is a better use of the current in the current to force conversion.
So in the end, its not the SPL which is increased at same amp volume but the power efficiency of the system (less electrical watts for the same SPL). The total power handling is also increased.
This for 2 exciters. For 4 in series, parallel, to be checked.
Christian
I found the opposite, that the DAEX30HESF-4 is very hard to heat up. Do you have any HPF? You probably wont get much response in the low sub frequencies, but exciter will still try to do the work, resulting in heat instead of sound.
Only way I managed to heat them up has been to really push the sub frequencies, but with a HPF at 90Hz I have been throwing double their rated power and they still stay at ambient temp. If you are using them full range I would still put an HPF, but around 20-40Hz instead.
But without support they will start sagging eventually anyway. I finally worked out a solution for proper support and cable management for my plates.
It is five 3D printed parts that holds the exciters in place. One plate with holes for the M6 screws in the middle of the exciters, then four arms that screw into the frame that have a long hollow slot inside in which cabels can be pulled. Only way to keep them stackable was to add a separate little box for connectors on the outside of the frame.
Unfortunately the placement of the exciters on my excisting plates is not precise enough to just add the supports though, so need to redo them all
With speaker elements the common convention is that each doubling of number of elements will increase sensitivity by 3dB, and also increase power handling by double. Double the power gives another 3dB, resulting in a 6dB total increase. The same should be true for exciters, unless there is some cancellation happening when they work on the same plate.
So 4 exiters in series-parallel should give 12dB more than a single exciter if you give it 4x the power.