Burntcoil.
I understand that you have no problem using eq ,but I was hoping you would have at the least had a response up to 10k without eq so that we could match tests.
If the low level sounds have been blocked or not produced for whatever reason,your plot is down by 15db at 8k,eq will not recover them properly from the depths of noise and could affect the tests ,it would have been better to have had it performing properly to start with.
As you say, at the moment this is not the best time to get out the hammer and chisel so I will move on,by the way what glue did you use.
It just niggles me like an itch you can't scratch,I'd have to find the problem testing the exciter ,glue and panel separately,I'll just go and bang my head against a wall a few times and I'll be fine.
I'll try and move on taking into Account the problems.
Steve
I understand that you have no problem using eq ,but I was hoping you would have at the least had a response up to 10k without eq so that we could match tests.
If the low level sounds have been blocked or not produced for whatever reason,your plot is down by 15db at 8k,eq will not recover them properly from the depths of noise and could affect the tests ,it would have been better to have had it performing properly to start with.
As you say, at the moment this is not the best time to get out the hammer and chisel so I will move on,by the way what glue did you use.
It just niggles me like an itch you can't scratch,I'd have to find the problem testing the exciter ,glue and panel separately,I'll just go and bang my head against a wall a few times and I'll be fine.
I'll try and move on taking into Account the problems.
Steve
@Spedge.
I very much appreciate the interest and sympathise with the frustration Steve. Yes hammers and chisels best avoided for now, I have zero back-up.
Glue was a two part epoxy and it was a thin layer so I would be surprised if it was the glue.
Please go easy on the wall. Very difficult to get bricks at the moment.
Best
Burnt
I very much appreciate the interest and sympathise with the frustration Steve. Yes hammers and chisels best avoided for now, I have zero back-up.
Glue was a two part epoxy and it was a thin layer so I would be surprised if it was the glue.
Please go easy on the wall. Very difficult to get bricks at the moment.
Best
Burnt
Burntcoil.
You'll have to hear with me as I get a little emotional when releasing one of my potential patents
Anyway having just been reminded how this idea first started with the loan of the wharfedale panels by a friend a long time ago now.
He said he preferred the sound of the panels with the picture in the frame? But I must admit to being not very impressed.
A few years later I did try again using A4 paper over various panels but the measured response and sound wasn't that good so gave up.
It wasn't until even later when I was playing around with my ply panels,trying to tame the perceived harshness in the central area of the exciter using my finger moving across the exciter central surface area,that I noticed the response changing in the area I was interested in.
Obviously my finger wasn't the best tool for the job,and didn't want to permanently attach it to the panel,so I cut a strip of paper about 1inch wide and about 6inches long to move across the exciter area and watched the frequencies change,at a certain point the frequency would help level out the upper oil can (tectonics expression not mine)hump between 10k and 20k,but would also fill in the dips that always preceded it in the lower area leading up to 10k.
Now this is all well and good,not having such a lumpy HF response ,so stuck the paper strip in place using masking tape,only at the ends of course.
When I eventually sat down listening to music ,it suddenly dawned on me that the sound I had become used to ,listening to heavy panels ,such as podiums,wharfedale,my ply and various others,this had changed.
It suddenly had the atmosphere ,depth and life that I usually feel is missing,I have used a tweeter in the past to try and overcome this ,with only a little success,to be honest the panel response always had too much HF already ,which is why I could never understand why it sounded lacking in that area.
This was something else ,I believe that the strip of paper is acting like a passive radiator producing the light delicate atmospheric sounds that the heavy panel doesn't quite manage,but also correcting other problems along the way,to be discussed.
You won't notice huge amounts of output from such a small area,but the detail will be there.
You must not just place the paper strip over the centre of the exciter area,this does not work,it helps to watch the response as you are moving the paper across the area to find the right position,it is usually when approximately half of the exciter area is covered,but this can be very fiddly to get Wright as I'm sure the exact position changes with panel thickness and materials ,so it's a bit of trial and error im afraid.
As it is only two strips of paper and some masking tape it won't break the bank,but if done correctly it is well worth the effort.
Hope you don't all think I'm a total nutter,because of this.
I have done a bit more testing in the last few days and will take a few pics to show some improvements I've made.
All the best .
Steve
You'll have to hear with me as I get a little emotional when releasing one of my potential patents
Anyway having just been reminded how this idea first started with the loan of the wharfedale panels by a friend a long time ago now.
He said he preferred the sound of the panels with the picture in the frame? But I must admit to being not very impressed.
A few years later I did try again using A4 paper over various panels but the measured response and sound wasn't that good so gave up.
It wasn't until even later when I was playing around with my ply panels,trying to tame the perceived harshness in the central area of the exciter using my finger moving across the exciter central surface area,that I noticed the response changing in the area I was interested in.
Obviously my finger wasn't the best tool for the job,and didn't want to permanently attach it to the panel,so I cut a strip of paper about 1inch wide and about 6inches long to move across the exciter area and watched the frequencies change,at a certain point the frequency would help level out the upper oil can (tectonics expression not mine)hump between 10k and 20k,but would also fill in the dips that always preceded it in the lower area leading up to 10k.
Now this is all well and good,not having such a lumpy HF response ,so stuck the paper strip in place using masking tape,only at the ends of course.
When I eventually sat down listening to music ,it suddenly dawned on me that the sound I had become used to ,listening to heavy panels ,such as podiums,wharfedale,my ply and various others,this had changed.
It suddenly had the atmosphere ,depth and life that I usually feel is missing,I have used a tweeter in the past to try and overcome this ,with only a little success,to be honest the panel response always had too much HF already ,which is why I could never understand why it sounded lacking in that area.
This was something else ,I believe that the strip of paper is acting like a passive radiator producing the light delicate atmospheric sounds that the heavy panel doesn't quite manage,but also correcting other problems along the way,to be discussed.
You won't notice huge amounts of output from such a small area,but the detail will be there.
You must not just place the paper strip over the centre of the exciter area,this does not work,it helps to watch the response as you are moving the paper across the area to find the right position,it is usually when approximately half of the exciter area is covered,but this can be very fiddly to get Wright as I'm sure the exact position changes with panel thickness and materials ,so it's a bit of trial and error im afraid.
As it is only two strips of paper and some masking tape it won't break the bank,but if done correctly it is well worth the effort.
Hope you don't all think I'm a total nutter,because of this.
I have done a bit more testing in the last few days and will take a few pics to show some improvements I've made.
All the best .
Steve
Nurse, I say nurse! I believe young Spedge has been slipping his dried frog pills into the aspidistra pot again.
Interesting! A bit like a parasitic cone used on those old-fashioned full range cone jobbies everyone pays in gold bars for? Most interesting, and that is something I will experiment with despite my Poplar panels lazing about on the job on the squeaky bits.
Bad form publishing a patentable idea when everyone is on lock down and can't get near the patent office. Positively Eddisonian levels of cunning. There will, no doubt, be a stampede when the doors open.
Burnt
Interesting! A bit like a parasitic cone used on those old-fashioned full range cone jobbies everyone pays in gold bars for? Most interesting, and that is something I will experiment with despite my Poplar panels lazing about on the job on the squeaky bits.
Bad form publishing a patentable idea when everyone is on lock down and can't get near the patent office. Positively Eddisonian levels of cunning. There will, no doubt, be a stampede when the doors open.
Burnt
Plexi DML
Here is my latest DML adventure.
2x4 ft plexiglass .25 inch DML with biamped system. The OB full ranger and the super tweeter have been disconnected but are “nearby” for comparisons. Subs are OB 15” Altec 416 c. Yes, there is a big dB/w efficiency difference but so what... I turn down the subs. Running the subs below 125hz only. They play loud. Just got my minidsp so here goes.
Result.... wow! Just wow.
Here is my latest DML adventure.
2x4 ft plexiglass .25 inch DML with biamped system. The OB full ranger and the super tweeter have been disconnected but are “nearby” for comparisons. Subs are OB 15” Altec 416 c. Yes, there is a big dB/w efficiency difference but so what... I turn down the subs. Running the subs below 125hz only. They play loud. Just got my minidsp so here goes.
Result.... wow! Just wow.
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Dave - that looks awesome! I was missing your posts lately - looks like you've been busy!
I have so far only had experience with EXP panels with no frame or spine supporting the exciter, so as a test to see the difference a spine could make, I put together a cardboard panel and took some measurements with and without the spine. I was expecting quite a difference since I could feel a lot of vibration on the exciter housing without the spine and the cardboard is quite floppy - but there does not appear to be much. Prior to the measurements, I ran a frequency sweep on the panel and added isolation to points around the frame to dampen resonances (dots of soft butyl rubber). Guys, could you please give me your take on my results or how I got them? Thanks, Bruce.
I have so far only had experience with EXP panels with no frame or spine supporting the exciter, so as a test to see the difference a spine could make, I put together a cardboard panel and took some measurements with and without the spine. I was expecting quite a difference since I could feel a lot of vibration on the exciter housing without the spine and the cardboard is quite floppy - but there does not appear to be much. Prior to the measurements, I ran a frequency sweep on the panel and added isolation to points around the frame to dampen resonances (dots of soft butyl rubber). Guys, could you please give me your take on my results or how I got them? Thanks, Bruce.
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Thanks for the feedback Spedge. Funny, this is my first build, but my intuition is that the thin wood is pretty good.
After about 10 hours of playing, I started getting some ugly resonance on the short wire that bridges the 2 exciters on each board and also on the wires themselves at around 400hz. Was very annoying and haven't quite isolated the cause.
The speaker wire is a pretty heavy grade, so could be some combination of that and the exciters breaking in. Having something standing behind the speakers to support the weight of the wires has made it go away for now.
Maybe I'm discovering something others here have known for a while? Namely, that you need to attach the exciters with some other means than the included 3M glue strips?
After about 10 hours of playing, I started getting some ugly resonance on the short wire that bridges the 2 exciters on each board and also on the wires themselves at around 400hz. Was very annoying and haven't quite isolated the cause.
The speaker wire is a pretty heavy grade, so could be some combination of that and the exciters breaking in. Having something standing behind the speakers to support the weight of the wires has made it go away for now.
Maybe I'm discovering something others here have known for a while? Namely, that you need to attach the exciters with some other means than the included 3M glue strips?
Raph.
Let's face it,the way exciters have been marketed as a toy for making a noise on cardboard boxes ,has made them a laughing stock with the hifi community,plus even experts have trouble trying to understand dml,all they see is cone break up and distortions.
Covid.
Your exciters are being unbalanced by the wire,this is causing the exciter to rock sideways ,there is a danger of coil damage,a spine is called for to hold the magnets steady
I have been banging on about not using tape of any sort for at least 10 years now,welcome to the clud.
Steve
Let's face it,the way exciters have been marketed as a toy for making a noise on cardboard boxes ,has made them a laughing stock with the hifi community,plus even experts have trouble trying to understand dml,all they see is cone break up and distortions.
Covid.
Your exciters are being unbalanced by the wire,this is causing the exciter to rock sideways ,there is a danger of coil damage,a spine is called for to hold the magnets steady
I have been banging on about not using tape of any sort for at least 10 years now,welcome to the clud.
Steve
By the way ,the glue I have always used is pva,and I think it is essential to scuff the exciter foot with sandpaper to aid glue adhesion,shiny plastic is not the best surface to try and glue!!
I'm not saying pva is the best ,but I have always had good results with my 10watt exciters they have stayed on for years,if the panel is accidentally dropped heavily on it's side the exciter will sheare off,but not if a spine was fitted of course.
Steve
I'm not saying pva is the best ,but I have always had good results with my 10watt exciters they have stayed on for years,if the panel is accidentally dropped heavily on it's side the exciter will sheare off,but not if a spine was fitted of course.
Steve
I've been testing various materials with DAEX30HESF-4. I tested Ply 4, 6 mm, ceiling tiles, EPS 2,5 and 5 cm, cardboard and a big Ikea picture with some SEMI sturdy cup holders. I must say, that out of all of them I really like the sound coming out of the picture and from 2,5 cm EPS, but I still get a lot of base resonance as I'm afraid to stick them to any of the surfaces because that's the last excited that is available in Poland.
Any ideas what can I do to reduce the resonance without sticking the exciter onto the surface? I also found a double sided tape from 3m, similar to the one that Tech Ingredients guy used to talk about. Any idea if this will do? 3M VHB RP45 Double sided acrylic tape Thickness: 1,1MM
Any ideas what can I do to reduce the resonance without sticking the exciter onto the surface? I also found a double sided tape from 3m, similar to the one that Tech Ingredients guy used to talk about. Any idea if this will do? 3M VHB RP45 Double sided acrylic tape Thickness: 1,1MM
Wow, Dave - this is amazing and totally surprising coming from you. A few pages ago you were experimenting with composite materials, and now plexiglass! And the results are wow.
I use plexiglass a lot in my diy audio - for enclosures, but would never have considered plexiglass for DML panel material. This thread remains incredibly interesting and also confusing.
Exciter wobble.
I'm getting side tracked again ,but I think it is very important while I think of it,that if you are using your exciter to produce large amounts of LF without mounting on a spine,it will start to wobble uncontrollably,boosting the low end will make it even worse.
You can try and mount the cable on top of the exciter to try and balance it ,but The wire will have it's own resonance.
Tricky.
If like me you don't use your exciter down to these extreme levels ,free mounting is no problem,
My exciter have quite a large terminal on the side so balancing is a major problem.
Steve
I'm getting side tracked again ,but I think it is very important while I think of it,that if you are using your exciter to produce large amounts of LF without mounting on a spine,it will start to wobble uncontrollably,boosting the low end will make it even worse.
You can try and mount the cable on top of the exciter to try and balance it ,but The wire will have it's own resonance.
Tricky.
If like me you don't use your exciter down to these extreme levels ,free mounting is no problem,
My exciter have quite a large terminal on the side so balancing is a major problem.
Steve
Hey Steve, thanks for the tip!! You mean just something like plain old Elmers Glue All Multipurpose glue, which is a PVA glue? I would have thought you need some exotic epoxy concoction!
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I think your diagnosis then of "Exciter Wobble" is spot on Dr Steve, because it did seem to get worse when I pushed more LF to the DMLs.
My plan is to suspend the panels, one each on one of these things:
An externally hosted image should be here but it was not working when we last tested it.
I'll have to think about how best to incorporate the spine in there. Or perhaps will have to cook up something on the back that just "neutralizes" the weight of the wire.