Hi Leonard .
I think I have already mentioned further back on this site that the ordinary exciters we use do ,if freely mounted on the panel act as a bass shaker below about 100hz.
When playing low frequency sounds the exciter will start to bounce and shake the panel.
This was very noticeable on my very large 25mm eps panels ,the whole panel would start to shake uncontrollably,and start to walk along the floor!
The eps and the exciter were pushed to there limit and beyond.
The surface of the lower grade eps is not really strong enough to handle this kind of force for long periods.
The 10 watt exciter ,while capable of producing vast amounts of sound above 100hz, would start to get very warm if used below this.
There is also the problem of balancing the exciter!
The music played was the dark knight (batman ) by hanz zimmer .
Looking at the rta the LF response was quite simmer to the TLS I use, but without the ease .
Personally I would always use the TLS for LF if only to save my poor panels and exciter from excessive movement, and also interfering with the mid and high frequency.
A large 7x3ft bass panel was also not a permanent option for me.
Steve
I think I have already mentioned further back on this site that the ordinary exciters we use do ,if freely mounted on the panel act as a bass shaker below about 100hz.
When playing low frequency sounds the exciter will start to bounce and shake the panel.
This was very noticeable on my very large 25mm eps panels ,the whole panel would start to shake uncontrollably,and start to walk along the floor!
The eps and the exciter were pushed to there limit and beyond.
The surface of the lower grade eps is not really strong enough to handle this kind of force for long periods.
The 10 watt exciter ,while capable of producing vast amounts of sound above 100hz, would start to get very warm if used below this.
There is also the problem of balancing the exciter!
The music played was the dark knight (batman ) by hanz zimmer .
Looking at the rta the LF response was quite simmer to the TLS I use, but without the ease .
Personally I would always use the TLS for LF if only to save my poor panels and exciter from excessive movement, and also interfering with the mid and high frequency.
A large 7x3ft bass panel was also not a permanent option for me.
Steve
Hello geosand,
I have played around with the bass shaker as the "Bottom End" for my speaker system.
It's a open frame 6 mm laser cut steel frame that is ~28" high and 30" width with the cross bar mid way and I attached the bass shaker with a 1/4"sorbothane gasket backing the shaker to steel. I attached a 36"x24" carbon fiber panel to the shaker. I found that at the very low frequencies 1-30 Hz one really wants to have a stiff panel. The (XPS/EPS foams tend to distort because of flexing from air pressure. I had it placed under a open table and with a few watts feeding it it vibrated every thing off the table and even vases on shelves in the room. It really fills in the bottom end much better than any of my prior sub-woofers . Have to pay attention to the power and I used a geophone to help with measuring the 0-10Hz band as it couples the very low frequency modes of my listening are a I will try and post a couple of photos of the beast. Cheers,
Steve
I have played around with the bass shaker as the "Bottom End" for my speaker system.
It's a open frame 6 mm laser cut steel frame that is ~28" high and 30" width with the cross bar mid way and I attached the bass shaker with a 1/4"sorbothane gasket backing the shaker to steel. I attached a 36"x24" carbon fiber panel to the shaker. I found that at the very low frequencies 1-30 Hz one really wants to have a stiff panel. The (XPS/EPS foams tend to distort because of flexing from air pressure. I had it placed under a open table and with a few watts feeding it it vibrated every thing off the table and even vases on shelves in the room. It really fills in the bottom end much better than any of my prior sub-woofers . Have to pay attention to the power and I used a geophone to help with measuring the 0-10Hz band as it couples the very low frequency modes of my listening are a I will try and post a couple of photos of the beast. Cheers,
Steve
As we are talking about low frequency panel driving.
This patent (us3164221A)from 1961 but also re-invented in patent (us20060159293A1)1995 fig 8 shows another interesting way to drive a panel .
The patent states that the response is (somewhat)below 20cps to above1000cps ,and can also if wanted be above this.
I spotted this some years ago , but never got around to experiment with it,one day maybe?
This basically looks like a passive ABR to me maybe this is where they got the idea from ?it all depends on how you use it.
Sorry for not using a link but I can't figure out how to do this,if anyone wishes do this please do.
Thanks
Steve
This patent (us3164221A)from 1961 but also re-invented in patent (us20060159293A1)1995 fig 8 shows another interesting way to drive a panel .
The patent states that the response is (somewhat)below 20cps to above1000cps ,and can also if wanted be above this.
I spotted this some years ago , but never got around to experiment with it,one day maybe?
This basically looks like a passive ABR to me maybe this is where they got the idea from ?it all depends on how you use it.
Sorry for not using a link but I can't figure out how to do this,if anyone wishes do this please do.
Thanks
Steve
I forgot to mention why I found this patent interesting,the flat panel is being driven equally over the whole surface area by air pressure,so that that the panel moves in and out as one,in theory anyway.
The air pump type arrangement in the second patent can drive two panels opposing each other ,there are a lot of options that can be considered especially when you start thinking about it.
Steve
The air pump type arrangement in the second patent can drive two panels opposing each other ,there are a lot of options that can be considered especially when you start thinking about it.
Steve
Hello Moldie,
I have been using PUI exciters and for my Bottom End it's the ASX08604-SW-R
This driver has no problem driving the CF panel at a subsonic frequency of 1 Hz
It is the first time I was able to reproduce the low E bass of the pedal organ in the opening piece of Also sprach Zarathustra,"Einleitung, oder Sonnenaufgang" (Introduction, or Sunrise). You actually feel that note and I had no other sub woofer be able to generate that note with such realism. I attribute this to the low mass of the CF panel and having it free of any baffle.
Cheers,
Steve
I have been using PUI exciters and for my Bottom End it's the ASX08604-SW-R
This driver has no problem driving the CF panel at a subsonic frequency of 1 Hz
It is the first time I was able to reproduce the low E bass of the pedal organ in the opening piece of Also sprach Zarathustra,"Einleitung, oder Sonnenaufgang" (Introduction, or Sunrise). You actually feel that note and I had no other sub woofer be able to generate that note with such realism. I attribute this to the low mass of the CF panel and having it free of any baffle.
Cheers,
Steve
moldie,
Exciting and ambitious plan. It'll be fun. Here are some of my thoughts:
Nothing wrong with this exciter but it may not be the best for your plan. You may not be able to tell easily from the images, but this is about the heaviest and most top heavy exciter, with relatively small adhesive area. I think this exciter might really need some support from a spine, which it doesn't seem like you plan to do, at least not initially. I'd suggest instead the Dayton Ultra instead:
Dayton Audio - DAEX32U-4 Ultra 32mm 20W 4 Ohm
it's lighter, lower profile, and more mounting area. I've had several mounted without spine support for months and they are doing fine. I fear the same wouldn't be true of the 30HESF-4. If you really want the extra power, then maybe go for the Thruster instead of the Ultra.
Don't bet too heavily on the 4:1 aspect ratio based on my earlier input. I've learned since then that some modes provide much stronger output than others, so simply spacing all the modes evenly doesn't really work as well as I expected. That said, when I played around with real "free" (i.e. hung from strings) plywood panels I had the best results with ratios of from about about 2.6:1 to 3:1. Burnt's results did look pretty good so do seem to be worth emulating.
If you read more carefully you will see this doesn't have a PVC foam core. Rather, it's "lightweight" polyethylene. You might infer from "lightweight" that it's foam, but more likely they are just saying that solid polyethylene is light compared to aluminum. That said, I've tried a material like this and the sound was pretty good, but output was low, because it's still pretty heavy. A similar material that works a bit better is aluminum faced with a corrugated (not solid) PE core. This is lighter and hence gives more output with the same power. To me this corrugated version was comparable to a good plywood panel.
Alumalite(R) | Corrugated Plastic Core Panels | Aluminum Composite Panel
Lastly, I wouldn't go too far before trying a few panels mounted to frames using insulation foam around most or all of the perimeter. Personally I've found that arrangement to be better than the "hanging from strings" style. Maybe you will too, or maybe not. But at least you will find out earlier rather than later.
Eric
Exciting and ambitious plan. It'll be fun. Here are some of my thoughts:
Nothing wrong with this exciter but it may not be the best for your plan. You may not be able to tell easily from the images, but this is about the heaviest and most top heavy exciter, with relatively small adhesive area. I think this exciter might really need some support from a spine, which it doesn't seem like you plan to do, at least not initially. I'd suggest instead the Dayton Ultra instead:
Dayton Audio - DAEX32U-4 Ultra 32mm 20W 4 Ohm
it's lighter, lower profile, and more mounting area. I've had several mounted without spine support for months and they are doing fine. I fear the same wouldn't be true of the 30HESF-4. If you really want the extra power, then maybe go for the Thruster instead of the Ultra.
Don't bet too heavily on the 4:1 aspect ratio based on my earlier input. I've learned since then that some modes provide much stronger output than others, so simply spacing all the modes evenly doesn't really work as well as I expected. That said, when I played around with real "free" (i.e. hung from strings) plywood panels I had the best results with ratios of from about about 2.6:1 to 3:1. Burnt's results did look pretty good so do seem to be worth emulating.
If you read more carefully you will see this doesn't have a PVC foam core. Rather, it's "lightweight" polyethylene. You might infer from "lightweight" that it's foam, but more likely they are just saying that solid polyethylene is light compared to aluminum. That said, I've tried a material like this and the sound was pretty good, but output was low, because it's still pretty heavy. A similar material that works a bit better is aluminum faced with a corrugated (not solid) PE core. This is lighter and hence gives more output with the same power. To me this corrugated version was comparable to a good plywood panel.
Alumalite(R) | Corrugated Plastic Core Panels | Aluminum Composite Panel
Lastly, I wouldn't go too far before trying a few panels mounted to frames using insulation foam around most or all of the perimeter. Personally I've found that arrangement to be better than the "hanging from strings" style. Maybe you will too, or maybe not. But at least you will find out earlier rather than later.
Eric
Koap.
Thank you very much.
The only problem is this patent says very little about the air pump type panel,the fig 8 only describes it as a distributed mode loudspeaker?
The other patent describes the invention more in depth and easy to understand ,and explains the other benefits of this design.
That is the one to read.
Thanks again.
Steve
Thank you very much.
The only problem is this patent says very little about the air pump type panel,the fig 8 only describes it as a distributed mode loudspeaker?
The other patent describes the invention more in depth and easy to understand ,and explains the other benefits of this design.
That is the one to read.
Thanks again.
Steve
Oh wow Steve that sounds amazing! If you won't mind, couple more questions:
- What source/amp are you using to get output below 20Hz (was under the impression most recordings have a high pass above 20Hz)?
- What thickness is the carbon fibre panel?
- How is the carbon fibre panel suspended/damped/hung other than the attachment point to exciter?
Contemplating another experimental setup with:
300X500mm 3K Carbon Fiber Board, thickness TBD
Dayton Audio BST-1
Mild steel welded frame. Would need to see if this wants to ring.
Eric, thank you for taking the time to write such a thoughtful and detailed response!
Noted, plan was to first do free hanging tests before moving on to splines. 3D printing brackets to link the screw holes in 30HESF-4 to flat surface of spline (damping material in between TBD). I'll get samples for both type of exciters then.
Good to know, do you have an idea how many dB's the output peaks differ? Anxious to see the results of Burntcoil's aspect ratio experiments post lockdown.
Well spotted! Evidently muddled up DI-BOND and KAPA mount (unfortunately not locally available, same for the Alumalite).
Worthwhile also testing Coru Print?
Good point, should not get too caught up in the analytical game and not enjoy just listening to the music. Suspect you are correct in that better results can be achieved via damped designs. The reason for the bulk of my initial experiments to be free hanging are:
In terms of insulation foam around the edges, do you think adhesive foam strip (with another layer double sided adhesive tape atop) would work? I'm a bit unclear as to which specific foam surround is best.
Honoured for your input.
Dirk
PS. Long term project idea brewing for a portable Bluetooth rig.
Two orthogonally oriented DMLs atop a 3D printed subwoofer box ala HexiBox v.3. Powered by a number of 32700 LiFePO4 cells.
Noted, plan was to first do free hanging tests before moving on to splines. 3D printing brackets to link the screw holes in 30HESF-4 to flat surface of spline (damping material in between TBD). I'll get samples for both type of exciters then.
Good to know, do you have an idea how many dB's the output peaks differ? Anxious to see the results of Burntcoil's aspect ratio experiments post lockdown.
Well spotted! Evidently muddled up DI-BOND and KAPA mount (unfortunately not locally available, same for the Alumalite).
Worthwhile also testing Coru Print?
Good point, should not get too caught up in the analytical game and not enjoy just listening to the music. Suspect you are correct in that better results can be achieved via damped designs. The reason for the bulk of my initial experiments to be free hanging are:
- Quickly/easily/cheaply test a large number of panel materials.
- Better indication of each material's intrinsic properties (sift out which to do further damped testing on).
- Fastest way to replace the Logitech speakers currently in use 😛
In terms of insulation foam around the edges, do you think adhesive foam strip (with another layer double sided adhesive tape atop) would work? I'm a bit unclear as to which specific foam surround is best.
Honoured for your input.
Dirk
PS. Long term project idea brewing for a portable Bluetooth rig.
Two orthogonally oriented DMLs atop a 3D printed subwoofer box ala HexiBox v.3. Powered by a number of 32700 LiFePO4 cells.
I have 2 of the 16 ohm models. Did you mount them on or through the Panel? I found that just laying them on the panel didn't seem to do much, but I know they recommend cutting a 70mm hole for them to sit in/thru rather than laying on the surface of the panel (Yes I know they sell a mounting kit for surface mounting). Hoping two in parallel will provide more SPL...I'm thinking of trying them on some ultra-light EPS (if they don't fall apart from the shaking lol), but maybe a heavier/denser surface would work better?
Geo
Koap.
Thank you once again,much appreciated.
Tagis.
Pui have a nice looking range of exciter and shakers at reasonable prices.
Is the shell of the shaker metal or plastic?
Steve
Thank you once again,much appreciated.
Tagis.
Pui have a nice looking range of exciter and shakers at reasonable prices.
Is the shell of the shaker metal or plastic?
Steve
Tagis.
It states that the response of the shaker goes up to 10.5k,any chance you can show the full frequency response when you do your tests?
It also states that it is a silent shaker which would be good.
Steve
It states that the response of the shaker goes up to 10.5k,any chance you can show the full frequency response when you do your tests?
It also states that it is a silent shaker which would be good.
Steve
Hello, I recently discovered exciters and am playing with a couple. I have a couple questions though.
I have a home stereo receiver that puts out 50 watts per channel at 8ohm. But most of the exciters Ifind are 4 ohm or are under powered like 25w
Ive been reading thru these pages and several people have claimed one exciter sounded better than running 2 per panel in series? is that correct?
There seems to be limited 8ohm exciteres with the 40w spec they are usually only 25w.
I am using the pink foam boards from home depot for cost effective build. Maybe later ill try some birch or something
I have a home stereo receiver that puts out 50 watts per channel at 8ohm. But most of the exciters Ifind are 4 ohm or are under powered like 25w
Ive been reading thru these pages and several people have claimed one exciter sounded better than running 2 per panel in series? is that correct?
There seems to be limited 8ohm exciteres with the 40w spec they are usually only 25w.
I am using the pink foam boards from home depot for cost effective build. Maybe later ill try some birch or something
Yes, that will work. In fact that is how I built my DMLs. But for prototyping, there is a simpler way. rather than use double sided tape on top, you can use spray adhesive. Apply the spray adhesive to the face of the foam, then apply the panel on top of that. But before applying the panel to the spayed foam, wait until it's not super tacky. That way, you will be able to remove the panel from the foam without damaging the foam, so you can reuse the foam for the next panel you want to test. If it has lost its tack, just spray it with another shot of adhesive.
I don't know what the best foam is, but I do my prototyping with this:
https://www.lowes.com/pd/M-D-10-ft-x-3-4-in-Gray-Window-Seal-Foam-Window-Weatherstrip/1096049
And final builds with this: (also 3/4" wide by 1/2" thick)
McMaster-Carr
the EPDM is more durable and I think the black looks better so is good for a final build. But it's expensive and the adhesive is really strong so it's hard to reuse without destroying it. The gray stuff is cheap and easily peeled off for reuse, so it's great for prototyping. I have not noticed any difference between the two as far as their impact on the panel response.
Eric
Regarding two exciters vs. one, opinions vary. But my observation is that two well placed exciters can be better than a single one (that is, provide flatter response with no other bad effect), while two poorly placed exciters can be worse than a single one.
Do try some plywood, I prefer the 1/4" plywood sold as underlayment. It's very inexpensive, sounds good, and some even look pretty nice. Be prepared for the SPL to be much lower than the pink foam. But you might like the sound quality better, it is very different.
Eric
So for my shop speakers I can fit 2x3 panels so you think I should try the plywood? For eciters on plywood what size do you recommend for my 8ohm receiver? Should I go with larger 32mm in series?
Then I also want to build some 2x2 pink foam ones for my daughters bedroom using a tiny bluetooth amp so Im thinking i should just use smaller 19mm exciters for that?
Dirk,
I have a way of prototyping damped/framed panels that I think is as fast or faster than testing free hanging panels. I have a simple wooden frame shown in the image below. The size can be easily changed just by removing the single screw at each corner, sliding the frame parts to a new size, then replacing the screws in the new locations. The change could be made even faster using corner clamps like these instead of screws:
https://www.lowes.com/pd/Pony-3-in-...uQsvneU_cxXVXStHKbYv8ct14gU9hHEUaAhJeEALw_wcB
I apply the foam to the frame in whatever arrangement I want to try, apply spray adhesive as I described previously, and stick the panel to the foam. Then, with the frame and panel resting on the wash basket as shown, I add the exciter(s). Now the really sweet part of this is that, since the panel is horizontal, I don't need to actually attach the exciter. It can simply be placed on top of the panel with a little weight (say 200g) to hold it in place (I also put a little foam between the exciter and the weight). With this method I can try any number of exciter positions without ever having to attach the exciter to the panel.
So this method allows very quick testing of various:
panel materials
panel sizes
exciter types, number and locations
foam damping arrangements
Eric
