Hi Leonard
That's wonderful to hear about your honeycomb cardboard experience, thank you! Your thought with mixing materials (take the best from each
) and different shapes is very welcome. This allows an 'out of the box' thinking, in my opinion. The risk is, to get lost in the material labyrinth;-) With my panel, which is similar in weight with yours. size a little different and thickness is 13mm, the bass (body) is definitely missing but lovely mids and highs (a little too much prominent). With my paperboard honeycomb panels I got a better tonal balance but missing the wonderful details of the cardboard panel. Now I'm in process to make 3 or 4 layers with paper and rice glue to replace one paperboard layer and to get more stiffness at the exciter-side. It is mounted on a small poplar ply in a 'drop shape' at 1/3 (length) offcentered (wide). The working processes in modifying those panels are somewhat time-consuming and I hope to be ready next week for a first listening.
Would be great to hear about your projects.
Eric
You are right - I have certainly not seen combinations of materials here yet. So, what combination is giving you the best results? Can you share more details - materials used, how are they stuck together, size of the panels, on which side is the exciter, etc.?
PS: Looks like 100ohms posted the same time as me, asking for more details too
Hi Leonard
That's wonderful to hear about your honeycomb cardboard experience, thank you! Your thought with mixing materials (take the best from each
Eric
Thank you for your kind words. I will keep you all posted about my future projects and findings
I didn't mean two materials stuck together, that I meant was using seperate panels with different materials. Currently I use one panel honycomb and two panels wood with the sizes as in the post and another small piece of wood, that once was the backside of a cabinet, but I will replace that soon with another honycomb panel.
The two woodpanels are wired in series using these DAEX30HESF-4 and the other panels are wired in series using the smaller DAEX25FHE-4, with the goal to tone down the, like 100Ohm described, sometimes very prominent highs of the honeycomb.
So far it works great for me, but I am constantly experimenting and changing some things (for me half the fun of the project)
I have tried wiring them in parallel but this can be a very heavy load for the amp (an old arcam delta 290 atm)
In the past I used a similiar setup but with 2 A3 sized pieces of XPS with a paperlayer on each side in combination with the wood panels, which I also liked alot, kinda like a mid and tweeter combi but I havn't tried crossing them over at different frequencies yet.
I have thought about applying one sheet of fiberglass to one or both sides of a panel to see how that works, but haven't got around to trying that.
-Leonard
Hi Dave
thank you very much for the keywords with the graph. It is very helpful for me.
Eric
Hi Steve
thank you for sharing this. It's really impressing and sounds very good for me, beside the 's' and similar consonants, which have a high level. On your codona record, the high tubular bells are a little exaggerated too for me, when listening with my headphone. Your recordings will be very useful for me, when I'm in train of finishing (final mastering) my honeycomb experiment.
Eric
Hi Eric.
The Damien Rice live recording is a very raw recording(the CD was given away free with a news paper,I found it in a charity shop!) You feel that you are Actually there in the audience,with all the laughing and whistling going on all around you,you can even hear the reverberation of the hall!.
The reason I chose the godona track ,was for the up front clanging metal sounds, even on headphones straight out of the CD player they sound the same.
Not sure what instrument he is clanging though?but not tubular bells .
Not that it notices on the recording,but I recorded the codona track at,very,very loud volume,with the microphone very close to the panels,to help keep the microphone, computer noise down,and hoped it would give an impression of how loud the trumpet could go,but it still sound like a normal recording,you wouldn't guess that I was sitting 10ft back with my fingers in my ears!
Sometimes I stand between the panels with my headphones on,and compare the sound,listening to the panels in this position is like wearing a massive pair of headphones and the two sound very similar.
One thing I have noticed though is that the panels give more low level detail of sounds that are hard to pick out on the headphones.
Many times I have thought that there was something going wrong with the panel ,only to find after listening hard on the headphones,that the sound is on the CD !!!
Actually about a month ago I ripped my whole system apart after realising it wasn't my panels having problems,I really thought that a piece of my equipment was going up the shute,I was at my wits end,spent nearly all day trying to find the culprit ,only to find it was the audio test disc that had the distortions ,not my system!!!
I Still haven't managed to put it all back together yet!
If there is anything wrong with a recording the panels will pic it out!!! Be warned!
Steve
The Damien Rice live recording is a very raw recording(the CD was given away free with a news paper,I found it in a charity shop!) You feel that you are Actually there in the audience,with all the laughing and whistling going on all around you,you can even hear the reverberation of the hall!.
The reason I chose the godona track ,was for the up front clanging metal sounds, even on headphones straight out of the CD player they sound the same.
Not sure what instrument he is clanging though?but not tubular bells .
Not that it notices on the recording,but I recorded the codona track at,very,very loud volume,with the microphone very close to the panels,to help keep the microphone, computer noise down,and hoped it would give an impression of how loud the trumpet could go,but it still sound like a normal recording,you wouldn't guess that I was sitting 10ft back with my fingers in my ears!
Sometimes I stand between the panels with my headphones on,and compare the sound,listening to the panels in this position is like wearing a massive pair of headphones and the two sound very similar.
One thing I have noticed though is that the panels give more low level detail of sounds that are hard to pick out on the headphones.
Many times I have thought that there was something going wrong with the panel ,only to find after listening hard on the headphones,that the sound is on the CD !!!
Actually about a month ago I ripped my whole system apart after realising it wasn't my panels having problems,I really thought that a piece of my equipment was going up the shute,I was at my wits end,spent nearly all day trying to find the culprit ,only to find it was the audio test disc that had the distortions ,not my system!!!
I Still haven't managed to put it all back together yet!
If there is anything wrong with a recording the panels will pic it out!!! Be warned!
Steve
Just stumbled upon this interview about podium speakers, haven't seen it being linked here, so there you go:
6moons audio reviews: Podium Sound Model 1
I find this part the most interesting:
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]" How did you achieve the amazing bass extension?
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Although the size of the vibrating element (panel), density, surface tension and a few other factors affect the bass extension, that is not really what you are asking. The proper answer is in relation to the sound-bridge parts of the loudspeaker. As you saw [while Shelley was doing the repair job on one speaker], I use a high-quality, completely inert, partially rigid rubber to hold the panel in particular places. And if one looks at the loudspeaker with light behind it, one will see some strange dark spots on the sides, which are not aligned with each other and seem to have no relationship with each other at all. But the placement of these sound bridges is absolutely critical and crucial to the bass extension. By adding these to the design, I can alter flaws in the frequency response, sometimes by in excess of a (perceived) 14dB.
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]As you can imagine, the placement of these sound bridges is what takes so much time in the design and cannot really be measured. This is where I will do the design many times until I find an arrangement which is both simple and effective. You may be interested to know that I have a design for a Podium 1 which uses a very large number of sound bridges and absolutely no built-in electronics. But I did not like the performance and the complexity of the physical design concerned me so I went with the electronic/sound-bridge hybrid.
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Who knows, perhaps one day I will have access to a programmable laser that can carve the surface of a vibrating element for me in the same way a violin maker carves his cabinets - and then I will use absolutely no electronics and very few soundbridges, if any. "[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]This kinda correlates to my findings with the styrofoam panel I shared in a previous post. I will definitly investigate that further...
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]-Leonard
[/FONT]
6moons audio reviews: Podium Sound Model 1
I find this part the most interesting:
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]" How did you achieve the amazing bass extension?
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Although the size of the vibrating element (panel), density, surface tension and a few other factors affect the bass extension, that is not really what you are asking. The proper answer is in relation to the sound-bridge parts of the loudspeaker. As you saw [while Shelley was doing the repair job on one speaker], I use a high-quality, completely inert, partially rigid rubber to hold the panel in particular places. And if one looks at the loudspeaker with light behind it, one will see some strange dark spots on the sides, which are not aligned with each other and seem to have no relationship with each other at all. But the placement of these sound bridges is absolutely critical and crucial to the bass extension. By adding these to the design, I can alter flaws in the frequency response, sometimes by in excess of a (perceived) 14dB.
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]As you can imagine, the placement of these sound bridges is what takes so much time in the design and cannot really be measured. This is where I will do the design many times until I find an arrangement which is both simple and effective. You may be interested to know that I have a design for a Podium 1 which uses a very large number of sound bridges and absolutely no built-in electronics. But I did not like the performance and the complexity of the physical design concerned me so I went with the electronic/sound-bridge hybrid.
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]Who knows, perhaps one day I will have access to a programmable laser that can carve the surface of a vibrating element for me in the same way a violin maker carves his cabinets - and then I will use absolutely no electronics and very few soundbridges, if any. "[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]This kinda correlates to my findings with the styrofoam panel I shared in a previous post. I will definitly investigate that further...
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]
[/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]-Leonard
[/FONT]
Tagis.
I've now watched quite a lot of his video's , very interesting.
Not sure about knocking up a DIY exciter ,but who knows?
What is the best exciter design, moving coil,moving magnet, piezoelectric,thin film,other?
Maybe something totally new?
I have thought about piezoelectric exciters ,but it means investing in a amp, I'd have to put my hand in my pocket, ouch!
Steve
I've now watched quite a lot of his video's , very interesting.
Not sure about knocking up a DIY exciter ,but who knows?
What is the best exciter design, moving coil,moving magnet, piezoelectric,thin film,other?
Maybe something totally new?
I have thought about piezoelectric exciters ,but it means investing in a amp, I'd have to put my hand in my pocket, ouch!
Steve
Occasinally, I use that exact technique of vibrating a piece wood with a small neo magnet and a iron core inductor to determine the fundamental vibrational frequency of of a guitar top. The inductor need not touch the top to work( just be held very close). This application was described by Brian Burns in mid 1970s.
From personal experience I can tell you that this is extremely inefficient and very hard on amplifiers. I don’t know what the impedance characteristics of my ferrite core is but my amp doesn’t like it(vibrates and overheats) and I don’t use it for extended periods- just brief tests.
This is attractive for simplicity but needs lots of work to use it for audio Hi Fi in DMLs
That is a beautifully simple exciter design which looks fun to experiment with but Dave is right it needs work.
A few thought below, because yes I am tempted.
The force available from the motor is defined by F = BLi where B = magnetic flux, L = length of wire in the magnetic field and i = current. To increase F you need to increase those factors but there are limits.
To increase B you need an N52 grade magnet as a minimum but there will be a limit on how big a magnet you can use as an increase in mass reduces the acceleration available and therefore the responsiveness.
The closer you can get the magnet to the coil the higher the magnetic flux as well so this will reduce displacement which reduces output- its always a balance.
You can increase L by using more wire but coils are low pass filters and if you go too far in this direction you will reduce the top end response. If you have ever taken a tweeter apart to repair it you will know the voice coil is tiny.
That doesn’t mean it is not worth pursuing but you would need to pay close attention to the top end response if you are going to increase L.
This means the best way to increase output would be something like
Use an N52 grade coin shaped magnet- probably not thicker than 2mm to keep the mass down.
Keep the distance between the coil and the magnet small- I would suggest a maximum of two millimetre
Increase the amount of wire in the coil until you hit the 20kHz roll-off.
Increase the current to the coil.
The amplifier drive problem can be solved using a transformer to match the output impedance of the amp with the input impedance of the motor which you will have to measure. This will have to be a custom wound transformer but thats not too hard as there are kits available.
I would go for an array of these micro-drivers driven by a single transformer.
@ tagis, Intriguing, thanks for the share !
A few thought below, because yes I am tempted.
The force available from the motor is defined by F = BLi where B = magnetic flux, L = length of wire in the magnetic field and i = current. To increase F you need to increase those factors but there are limits.
To increase B you need an N52 grade magnet as a minimum but there will be a limit on how big a magnet you can use as an increase in mass reduces the acceleration available and therefore the responsiveness.
The closer you can get the magnet to the coil the higher the magnetic flux as well so this will reduce displacement which reduces output- its always a balance.
You can increase L by using more wire but coils are low pass filters and if you go too far in this direction you will reduce the top end response. If you have ever taken a tweeter apart to repair it you will know the voice coil is tiny.
That doesn’t mean it is not worth pursuing but you would need to pay close attention to the top end response if you are going to increase L.
This means the best way to increase output would be something like
Use an N52 grade coin shaped magnet- probably not thicker than 2mm to keep the mass down.
Keep the distance between the coil and the magnet small- I would suggest a maximum of two millimetre
Increase the amount of wire in the coil until you hit the 20kHz roll-off.
Increase the current to the coil.
The amplifier drive problem can be solved using a transformer to match the output impedance of the amp with the input impedance of the motor which you will have to measure. This will have to be a custom wound transformer but thats not too hard as there are kits available.
I would go for an array of these micro-drivers driven by a single transformer.
@ tagis, Intriguing, thanks for the share !
Last edited:
Hi Steve, apologies I missed your question(s) earlier. Still using polycarbonate, but haven't been playing with the DML's much, as Covid has forced me to share my 'office/spare bedroom/experimentation sound studio' with my daughter who has been home schooling. Hope to get back to them, DML's, soon. Might I add, from your recordings I really like your taste in music. Regards, Simon
I should point out that this recording and the codona recording was done on a 8 inch or so panel that I knocked up and was up and running in no longer than 15mins,this is the beauty of smaller panels using 2mm card from a box my wife was throwing away,the only tools used was a pair of scissors and some double sided tape (I'm still waiting for my blue Peter badge) usually I treat the panel with PVA and tweek the sound in various ways,but I was in a hurry.
Other panels I have used 1mm card glued together with PVA,the card was from old serial boxes,also egg boxes,and paper-mache surprisingly with good results.
wood pulp has been a favourite for cone speakers for sometime now so shouldn't be surprised it sounds so good.
I hope this hasn't put anyone off.
Steve
Other panels I have used 1mm card glued together with PVA,the card was from old serial boxes,also egg boxes,and paper-mache surprisingly with good results.
wood pulp has been a favourite for cone speakers for sometime now so shouldn't be surprised it sounds so good.
I hope this hasn't put anyone off.
Steve
That should be the Damien Rice recording not the codona recording
The method used to do the recordings,has been a long and hard slog,but is basically simple, I've downloaded some recording apps and am now using my gallery note 4 using(I know it's old ,like me,but it works) the two microphones in the top and bottom of the phone for stereo (didn't know that it had them there, could even make it into a dummy head?)
The sound is remarkably good with good frequency response and silent and with no strange noises,the annoying thing was the app said it was MP4 but it was m4a or whatever,so I still have to go through conversion processes.
I had a thought that to make comparisons by recording the original from CD or maybe YouTube,or maybe recording from YouTube and everyone could listen to YouTube to compare,it was just a thought,so you would know what the original track sounded like?
Just a thought.
Steve
The method used to do the recordings,has been a long and hard slog,but is basically simple, I've downloaded some recording apps and am now using my gallery note 4 using(I know it's old ,like me,but it works) the two microphones in the top and bottom of the phone for stereo (didn't know that it had them there, could even make it into a dummy head?)
The sound is remarkably good with good frequency response and silent and with no strange noises,the annoying thing was the app said it was MP4 but it was m4a or whatever,so I still have to go through conversion processes.
I had a thought that to make comparisons by recording the original from CD or maybe YouTube,or maybe recording from YouTube and everyone could listen to YouTube to compare,it was just a thought,so you would know what the original track sounded like?
Just a thought.
Steve
Hello everyone,
I came up with an idea for a frame for the panels:
- Make a simple wooden frame the size of the panels
- Put threaded rods through the corners and along the edges as needed
- Glue some accoustic foam or some other spongy material on it
- Drill holes in the panels to fit the threaded rods
- fasten the panels using wingnuts and rubber spacers
So you can controll the amount of dampening along the edges with the wingnuts.
I made a crude prototype for testing, to fit some 30x110cm panels inspired by Burnt's "Tall Blondes", I'll attach some pictures.
First listening impressions are pretty good, I am going to use these as desk speakers for my PC.
Should be easy to adapt the design to all kinds of panel materials and sizes and if you keep the dimension the same panels can be easily swapped to provide a controlled enviroment to test different materials.
It would be great if you could provide some feedback and suggestions on how to improve the design.
Also I'm thinking about purchasing a mic for testing and came across the miniDSP Umik-1, which seems to be a good candidate and I was wondering if someone here has any experience with that model or could recommend a different model in the same pricerange.
-Leonard
I came up with an idea for a frame for the panels:
- Make a simple wooden frame the size of the panels
- Put threaded rods through the corners and along the edges as needed
- Glue some accoustic foam or some other spongy material on it
- Drill holes in the panels to fit the threaded rods
- fasten the panels using wingnuts and rubber spacers
So you can controll the amount of dampening along the edges with the wingnuts.
I made a crude prototype for testing, to fit some 30x110cm panels inspired by Burnt's "Tall Blondes", I'll attach some pictures.
First listening impressions are pretty good, I am going to use these as desk speakers for my PC.
Should be easy to adapt the design to all kinds of panel materials and sizes and if you keep the dimension the same panels can be easily swapped to provide a controlled enviroment to test different materials.
It would be great if you could provide some feedback and suggestions on how to improve the design.
Also I'm thinking about purchasing a mic for testing and came across the miniDSP Umik-1, which seems to be a good candidate and I was wondering if someone here has any experience with that model or could recommend a different model in the same pricerange.
-Leonard
Attachments
UMIK-1 is great. I pay an extra $20 and buy it through cross spectrum labs and they provide third party calibration. You may need to open up mic (spanner ring) and set dip switch to set proper gain for your application. Get a $20 SPL meter from Amazon to set absolute SPL calibration periodically.