Ed, good idea!.
Just a quick note(had a 30 minute listen) of the performance of the SOUND PADS.............
...... surprising bass, good midrange, not bad highs, not bad, but not brilliant : very similar to what you would expect from an average full range driver - dual cone type.
The plastic corrugated coreflute I'm using can definately be improved on in the form of corrugated cardboard as suggested by theAnonymous1.
Have an idea in making a SHELLAC VARNISH(even ROSIN based varnish) to coat the cardboard. Will try on some small samples first to see what the result is.
Looking to harden the surfaces without causing warping.
Just a quick note(had a 30 minute listen) of the performance of the SOUND PADS.............
...... surprising bass, good midrange, not bad highs, not bad, but not brilliant : very similar to what you would expect from an average full range driver - dual cone type.The plastic corrugated coreflute I'm using can definately be improved on in the form of corrugated cardboard as suggested by theAnonymous1.
Have an idea in making a SHELLAC VARNISH(even ROSIN based varnish) to coat the cardboard. Will try on some small samples first to see what the result is.
Looking to harden the surfaces without causing warping.
Well I must confess that I am impressed with the sound of these little gadgets. They are not junk or cheap noise makers in my opinion.
I was prepared for a weak and thin sound but the reverse is apparent. Man, can these things vibrate a large panel or what!!!?
That, is where a few facts come to light :
1. If the panel edges or panel itself touch anything, and that includes thin wires, you will hear it, believe me. That's probably why the Audio Express magazine article recommended that the panels be suspended from the ceiling in mid air for best sound.
2. The corners of the panel are the most likely spots to buzz or resonate. Is this why the PODIUM speakers have(quote) ''ROUNDED EDGES BECAUSE THEY JUST SOUNDED BETTER THAT WAY'' ?
3. If the panels are to be mounted on a frame they will ABSOLUTELY require some form of rubber edge support/damping as suggested by Ed. Plus, pieces of blutak or something similar can be positioned in various places by experimentation as they can easily be removed or shifted as required. This may help in damping out any problems in regards to resonance.
4. As mention by theAnonymous1 and I agree, coreflute panel is not ideal and there are other alternatives to try.
After researching all the marketing hype regarding this technology which is a variant on the NXT principle, does it take rocket science for this to work? I think not.
On a positive note, the panels have that unmistakable ''coherency'' , ''crossoverless'' sound and musicality that comes with a full range driver.
In this case however, there is a huge room filling sound eminating in my study that is eery. Something that I have not experienced before.
Horns sort of do this, but in a different way - more up front, smack you in the face way which is not like the real thing from my experience.
Regarding the high frequencies, I can't truly say and conclude or agree that they are inadequate. On the contrary, some recordings sound superb in the high frequency department.
As most of us have been accustomed to forward firing high frequency ''death beams''(LOL) , these diffuse highs are at first strange sounding until further listening reveals that everything is still there only presented to the listener in a completely different way.Room acoustics/damping will play a huge part in the highs no doubt.
I own a large 2 way Azzura horn system and can already notice where it is lacking compared to the actual sound of live music in an acoustic environment which I am quite familiar with.
I guess NXT eciters on panels really are music /room/position dependant. Then there is the compatibilty and characteristic of the equipment, cables running them coming in to the equation.
If there are any knowledgeable NXT experts out there, I would love to hear your advice (or anyone else's for that matter).
I think this project can be licked and provide us with another great panel speaker that's easy to build and very cost effective
I was prepared for a weak and thin sound but the reverse is apparent. Man, can these things vibrate a large panel or what!!!?
That, is where a few facts come to light :
1. If the panel edges or panel itself touch anything, and that includes thin wires, you will hear it, believe me. That's probably why the Audio Express magazine article recommended that the panels be suspended from the ceiling in mid air for best sound.
2. The corners of the panel are the most likely spots to buzz or resonate. Is this why the PODIUM speakers have(quote) ''ROUNDED EDGES BECAUSE THEY JUST SOUNDED BETTER THAT WAY'' ?
3. If the panels are to be mounted on a frame they will ABSOLUTELY require some form of rubber edge support/damping as suggested by Ed. Plus, pieces of blutak or something similar can be positioned in various places by experimentation as they can easily be removed or shifted as required. This may help in damping out any problems in regards to resonance.
4. As mention by theAnonymous1 and I agree, coreflute panel is not ideal and there are other alternatives to try.
After researching all the marketing hype regarding this technology which is a variant on the NXT principle, does it take rocket science for this to work? I think not.
On a positive note, the panels have that unmistakable ''coherency'' , ''crossoverless'' sound and musicality that comes with a full range driver.
In this case however, there is a huge room filling sound eminating in my study that is eery. Something that I have not experienced before.
Horns sort of do this, but in a different way - more up front, smack you in the face way which is not like the real thing from my experience.
Regarding the high frequencies, I can't truly say and conclude or agree that they are inadequate. On the contrary, some recordings sound superb in the high frequency department.
As most of us have been accustomed to forward firing high frequency ''death beams''(LOL) , these diffuse highs are at first strange sounding until further listening reveals that everything is still there only presented to the listener in a completely different way.Room acoustics/damping will play a huge part in the highs no doubt.
I own a large 2 way Azzura horn system and can already notice where it is lacking compared to the actual sound of live music in an acoustic environment which I am quite familiar with.
I guess NXT eciters on panels really are music /room/position dependant. Then there is the compatibilty and characteristic of the equipment, cables running them coming in to the equation.
If there are any knowledgeable NXT experts out there, I would love to hear your advice (or anyone else's for that matter).
I think this project can be licked and provide us with another great panel speaker that's easy to build and very cost effective
el'Ol, I had saved a link to my P.C of such a site before my hard drive crash
The site was in English but was a Chinese company?
Anyway....has anyone got a link they can share?
Ed, yes, that's very interesting and would work. However, from What I'm hearing from a 3 foot X 2 foot polyprop. coreflute panel, I don't think it's needed.
There seems to be plenty of bass but the real test will be in my main listening room with TWO much larger panels and aditional exciters.
I'm expecting more bass and a good probability of more highs according to the technical papers regarding NXT panel dimensions and use of multiple exciters per panel.
I have just got hold of a 5.5 foot X 2.5 foot 2/8'' thick corrugated cardboard sheet to experiment with. In the next day or so, I will be experimenting with this as well as ''foam pvc''(expanded pvc) or ''Sintra'' board.
As I will be visiting my local sign making shop tomorrow, There may be other materials of interest, who knows?
As long as the panel material meets what we know as the basic requirements : light, rigid and not too thick, we will be on the right path I believe.
Then there's the fun of various and possible coatings??
The site was in English but was a Chinese company?
Anyway....has anyone got a link they can share?
Ed, yes, that's very interesting and would work. However, from What I'm hearing from a 3 foot X 2 foot polyprop. coreflute panel, I don't think it's needed.
There seems to be plenty of bass but the real test will be in my main listening room with TWO much larger panels and aditional exciters.
I'm expecting more bass and a good probability of more highs according to the technical papers regarding NXT panel dimensions and use of multiple exciters per panel.
I have just got hold of a 5.5 foot X 2.5 foot 2/8'' thick corrugated cardboard sheet to experiment with. In the next day or so, I will be experimenting with this as well as ''foam pvc''(expanded pvc) or ''Sintra'' board.
As I will be visiting my local sign making shop tomorrow, There may be other materials of interest, who knows?
As long as the panel material meets what we know as the basic requirements : light, rigid and not too thick, we will be on the right path I believe.
Then there's the fun of various and possible coatings??
The cardboard DOES NOT sound any good. It actually attenuates the high frequencies. Bass is better due to to a larger panel size no doubt,but that's about it. By the way the cardboard is actually thinner than I first thought.
Changing back and forth from polypropylene coreflute and corrugated cardboard, the difference is quite obvious. I have a set of drivers on each panel and switch from speaker A & B through my amplifier.
So, next step is to get hold of some large coreflute panels and stick all four exciters on one of the panels to see how it performs.
Not even going to bother with foamcore as I believe the secret is in the open cell corrugated interface that has the greatest effect on sound reproduction and the transfer of high frequencies.
It's a great pity that these exciters have been dismissed as toys or just noise makers. I am getting some fantastic sound here and I feel confident that the sound will only get better with some decent size panels correctly mounted in some frames.
Changing back and forth from polypropylene coreflute and corrugated cardboard, the difference is quite obvious. I have a set of drivers on each panel and switch from speaker A & B through my amplifier.
So, next step is to get hold of some large coreflute panels and stick all four exciters on one of the panels to see how it performs.
Not even going to bother with foamcore as I believe the secret is in the open cell corrugated interface that has the greatest effect on sound reproduction and the transfer of high frequencies.
It's a great pity that these exciters have been dismissed as toys or just noise makers. I am getting some fantastic sound here and I feel confident that the sound will only get better with some decent size panels correctly mounted in some frames.
I found one American and two German manufacturers of piezo actuators:
http://www.amercanpiezo.com
http://www.argillon.com
http://www.physikinstrumente.com
and one American shop:
http://www.piezo.com
6 g 20x60 mm Fs 60Hz seems to be common.
But is Fs below the operating range, as with dynamic drivers?
http://www.amercanpiezo.com
http://www.argillon.com
http://www.physikinstrumente.com
and one American shop:
http://www.piezo.com
6 g 20x60 mm Fs 60Hz seems to be common.
But is Fs below the operating range, as with dynamic drivers?
Interesting links el'Ol. Some of those piezos may be useful.Thanks for that.
Lat night I mounted all of the 4 drivers I have on the corflute sheet. The sound output increased noticeably of course, but, here's the thing.........the aditional two drivers were mounted to the far left and right of the panel.
As I was once again able to switch from one pair to the other quite easily and quickly, the sound quality was not as good as the more centrally mounted drivers.
It all makes sense now when you realise that the PODIUM speakers mount their drivers down the centre line of the panel width. Also noticeable from the photos on 6 moons , and as mentioned before, no one driver is positioned at the EXACT CENTRE of the panel - important?....yes, I think so.
Lat night I mounted all of the 4 drivers I have on the corflute sheet. The sound output increased noticeably of course, but, here's the thing.........the aditional two drivers were mounted to the far left and right of the panel.
As I was once again able to switch from one pair to the other quite easily and quickly, the sound quality was not as good as the more centrally mounted drivers.
It all makes sense now when you realise that the PODIUM speakers mount their drivers down the centre line of the panel width. Also noticeable from the photos on 6 moons , and as mentioned before, no one driver is positioned at the EXACT CENTRE of the panel - important?....yes, I think so.
Hi,
Regards, Timo
It's funny, many years ago I was involved in the development of the first piezo motors drivers for PI Ceramic, their manufacturer. If interested see Ansteuerelektronik und Leistungsendstufen für neuartige Piezomotoren hoher Leistungsdichte PI Ceramic 1996.
Regards, Timo
Changed the position of the sound pads so that I had them mounted in a straight vertical line. An improvement was noticed.
Here's an observation - two pads per channel is not sufficient in a large listening room unless you listen to your music at below normal or realistic levels. I was however, testing both channels on only one sheet of corflute(3 foot X 2 foot) which is far from ideal.
This was soon obvious when the pads were beginning to get warm as I increased volume and listened at a reasonably loud volume for about 30 minutes.
I think that four per channel(bearing in mind the resulting impedence change) at least is what's required to spread the power input between drivers to a safe level. Will do that tonight and run a mono (summed stereo) signal to the four pads wired up for eight ohms.
I'm not sure what the sensitivity rating of these pads are as they are not stated anywhere that I have seen? I presume that they would be in the low to mid 80's ?
Before I give the cardboard panel idea away, I might try to varnish with shellac to see what happens.
Here's an observation - two pads per channel is not sufficient in a large listening room unless you listen to your music at below normal or realistic levels. I was however, testing both channels on only one sheet of corflute(3 foot X 2 foot) which is far from ideal.
This was soon obvious when the pads were beginning to get warm as I increased volume and listened at a reasonably loud volume for about 30 minutes.
I think that four per channel(bearing in mind the resulting impedence change) at least is what's required to spread the power input between drivers to a safe level. Will do that tonight and run a mono (summed stereo) signal to the four pads wired up for eight ohms.
I'm not sure what the sensitivity rating of these pads are as they are not stated anywhere that I have seen? I presume that they would be in the low to mid 80's ?
Before I give the cardboard panel idea away, I might try to varnish with shellac to see what happens.
Thanks Damo.
The idea is that the cardboard needs to be hardened without adding too much mass.
I have been thinking along the lines of Shellac because it dries hard and there will be minimal, if any, shrinkage.
Some of these plastic based varnishes cause a considerable shrink on anything that's able to flex if forced to.
You should see what DOPE (used on model planes) does !!
Anyway, the whole project is on the line tonight (seriously !) if the 4 drivers still warm up at loudish levels. I mean they were not ''hot'' last night, but it's still a concern as to what it's doing to their life span.
The idea is that the cardboard needs to be hardened without adding too much mass.
I have been thinking along the lines of Shellac because it dries hard and there will be minimal, if any, shrinkage.
Some of these plastic based varnishes cause a considerable shrink on anything that's able to flex if forced to.
You should see what DOPE (used on model planes) does !!
Anyway, the whole project is on the line tonight (seriously !) if the 4 drivers still warm up at loudish levels. I mean they were not ''hot'' last night, but it's still a concern as to what it's doing to their life span.
O.K............all is well no drivers cooking or smoldering at high levels. Only slightly warm to the touch. When the number of pads increases to 6 per panel this should be adequate and sensitive enough for most amplifiers.
I have ordered another 4 pairs of SOUND PADS just this morning and had an interesting conversation with the supplier. We talked about the various panel materials tried and he stated that the most adequate material that has been used is CORFLUTE.
Hmmmmmm???..........maybe, but I'm not convinced until I try a giant piece of it. I do know that some commercial ceiling panels and picture frame NXT products use it quite successfully.
Last night I heard some surprising and very low frequencies (but not at subwoofer levels) occasionally show up while listening to classical music on FM radio. That was with corrugated cardboard propped up with a balsa wood stick from behind, so it looks promising that low frequencies can be extracted from large panel sizes.
What was not so pleasant was some buzzing/resonances around the edges of the cardboard and one or more of the drivers. The drivers are only held in place temporarily by cheap paper masking tape(re-useable!!) so I don't expect a perfect coupling in that area
I'm also not surprised that the edges buzz either - the panel was hacked off the side of a rectangular box with a rather blunt knife!!
However, if corrugated cardboard wins the panel material game, the edges will need to be treated or sealed with some sort of rubber or similar compound. There's a lot of energy shooting towards these edges - trust me
I have ordered another 4 pairs of SOUND PADS just this morning and had an interesting conversation with the supplier. We talked about the various panel materials tried and he stated that the most adequate material that has been used is CORFLUTE.
Hmmmmmm???..........maybe, but I'm not convinced until I try a giant piece of it. I do know that some commercial ceiling panels and picture frame NXT products use it quite successfully.
Last night I heard some surprising and very low frequencies (but not at subwoofer levels) occasionally show up while listening to classical music on FM radio. That was with corrugated cardboard propped up with a balsa wood stick from behind, so it looks promising that low frequencies can be extracted from large panel sizes.
What was not so pleasant was some buzzing/resonances around the edges of the cardboard and one or more of the drivers. The drivers are only held in place temporarily by cheap paper masking tape(re-useable!!) so I don't expect a perfect coupling in that area
I'm also not surprised that the edges buzz either - the panel was hacked off the side of a rectangular box with a rather blunt knife!!
However, if corrugated cardboard wins the panel material game, the edges will need to be treated or sealed with some sort of rubber or similar compound. There's a lot of energy shooting towards these edges - trust me
What type of corrugated cardboard are you using? The best type to use is very thin 5-layer double corrugate, like the example at this link.....
http://www.smurfitkappa-obalysturovo.com/DropdownMenu/Products/Corrugated+Cardboard/
Are you using the SoundPads as-is, or have you removed the exciters? The SoundPads are designed to dampen low frequencies to keep the excursion of the exciter in check. If you remove the exciter and build a frame that allows the motor to be firmly attached you will get much more low end. This way the exciter will act more like a conventional driver at low frequencies.
http://www.smurfitkappa-obalysturovo.com/DropdownMenu/Products/Corrugated+Cardboard/
Are you using the SoundPads as-is, or have you removed the exciters? The SoundPads are designed to dampen low frequencies to keep the excursion of the exciter in check. If you remove the exciter and build a frame that allows the motor to be firmly attached you will get much more low end. This way the exciter will act more like a conventional driver at low frequencies.
Is it possible to remove the actuator from any piezo tweeter? On Ebay you get the "PT1-1016" from various shops. They claim it works from 1kHz on crossoverless.
http://cgi.ebay.de/2-x-Hochtoener-P...14&_trkparms=72:1229|66:2|65:12|39:1|240:1318
Or is it just the horn flare that limits the operating range?
http://cgi.ebay.de/2-x-Hochtoener-P...14&_trkparms=72:1229|66:2|65:12|39:1|240:1318
Or is it just the horn flare that limits the operating range?
The Anonymous1, I'm using just the standard 3 layer double faced cardboard about 4mm thick in total. It's interesting that you feel the 5 layer version is better and I can get hold of this locally.
The SOUNDPADS are being used AS IS at the moment.
Can you give me some tips on how best to dismantle them without causing damage as that would be much appreciated
I agree that used without the attached circular stick on cardboard disk and those stupid ''arms'' would result in better sound as you have previously implemented, similar to the PODIUM speakers?
Did you have the panel free floating but held at just the four corners or the entire panel?.
What do you think was the cause of the RESONANCES you spoke of??
elOL, the speakers on ebay are similar to the ones I pulled apart.
All you do is remove the screws at the driver end of the horn and the back will come off exposing the rear of the piezo driver.
To me the sound of the piezo cones mounted on the large boards went down to about 800hz, but that was not measured and is only subjective based on listening.
You will still need an impedence matching transformer to get these things to go loud.
PARTS EXPRESS sell large 4 inch diameter screw on horn drivers ''similar to KSN1188'' that have a built in transformer. You would be better off trying those. They are LOUD
I know, because I have a pair.
Thinking of pulling them apart
The SOUNDPADS are being used AS IS at the moment.
Can you give me some tips on how best to dismantle them without causing damage as that would be much appreciated
I agree that used without the attached circular stick on cardboard disk and those stupid ''arms'' would result in better sound as you have previously implemented, similar to the PODIUM speakers?
Did you have the panel free floating but held at just the four corners or the entire panel?.
What do you think was the cause of the RESONANCES you spoke of??
elOL, the speakers on ebay are similar to the ones I pulled apart.
All you do is remove the screws at the driver end of the horn and the back will come off exposing the rear of the piezo driver.
To me the sound of the piezo cones mounted on the large boards went down to about 800hz, but that was not measured and is only subjective based on listening.
You will still need an impedence matching transformer to get these things to go loud.
PARTS EXPRESS sell large 4 inch diameter screw on horn drivers ''similar to KSN1188'' that have a built in transformer. You would be better off trying those. They are LOUD
I know, because I have a pair.Thinking of pulling them apart
Ziggy said:
This was actually a recommendation of NXT I had found in an article. I doubt I would be able to find the article again if I tried, it was a couple of years ago.
Ziggy said:Can you give me some tips on how best to dismantle them without causing damage as that would be much appreciated
I will take some pictures of an exciter so you can see what it looks like without the extra stuff attached. I believe they were just attached to the plastic shell with some double sided tape or glue on the back.
Ziggy said:
The entire perimeter of the panel was attached to the frame with 1/4" expanded foam tape. I don't know what was causing the resonances. I don't have any sound measurement equipment and I didn't spend much time experimenting with it.
TheAnonymous1, Thanks!!!.......I'll go the 5 layer cardboard laminate route. Is 5mm (approximately) too thick?
Great photos - they will help.
How did you remove the central voice coil ''foot'' from the cicular pad and what did you use to stick the voice coil/foot on to the new 5 layer stuff?
Your advise is much appreciated
Great photos - they will help.
How did you remove the central voice coil ''foot'' from the cicular pad and what did you use to stick the voice coil/foot on to the new 5 layer stuff?
Your advise is much appreciated
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.