On page 213 there is another interesting panel recording with photos !
This is how easy it is to produce good sounding panels if you know what to look for!
And the answer to your question ,would I replace my ordinary speakers with dml panels.
I discovered dml well over ten years ago,and have not gone back .
I only listen to dml now,but keep my transmission line speakers for reference,and to use as a sub for my panels
Steve.
This is how easy it is to produce good sounding panels if you know what to look for!
And the answer to your question ,would I replace my ordinary speakers with dml panels.
I discovered dml well over ten years ago,and have not gone back .
I only listen to dml now,but keep my transmission line speakers for reference,and to use as a sub for my panels
Steve.
Pixel1.
You might find page 253 interesting especially post 2530 .
This is when I stopped experimenting with small panels,as I had reached my goal ,further than my goal ,actually! Of producing a workable small panel.
Many years ago now,when I was playing the machine gun on one of my 60x120cm x25mm panels ,a friend of my wife's poked his head around the door and said he could feel his teeth rattling in his head
You could also feel the pressure pounding on your chest and lungs
The exciter was hardly moving but the panel was putting out such dynamics that it was as if there was a real machine gun in the room
And this was a plain sheet of 70 grade eps ,I was soooo excited,I'm sure only horns could match this.
At the time when I first discovered dml I was actually looking into using horn loaded speakers,but discovered ziggy's forum piezo NXT .
And then later NXT RUBBISH THINK AGAIN,on audiocircle ,which I joined in on.
PIEZO NXT type panel
It's been a long journey.
Steve.
You might find page 253 interesting especially post 2530 .
This is when I stopped experimenting with small panels,as I had reached my goal ,further than my goal ,actually! Of producing a workable small panel.
Many years ago now,when I was playing the machine gun on one of my 60x120cm x25mm panels ,a friend of my wife's poked his head around the door and said he could feel his teeth rattling in his head
You could also feel the pressure pounding on your chest and lungs
The exciter was hardly moving but the panel was putting out such dynamics that it was as if there was a real machine gun in the room
And this was a plain sheet of 70 grade eps ,I was soooo excited,I'm sure only horns could match this.
At the time when I first discovered dml I was actually looking into using horn loaded speakers,but discovered ziggy's forum piezo NXT .
And then later NXT RUBBISH THINK AGAIN,on audiocircle ,which I joined in on.
PIEZO NXT type panel
It's been a long journey.
Steve.
Pixel1.
It's probably the same for pro audio as it is for the hifi market .
Try talking to someone in the pro audio business about dml and see what sort of reaction you get.
They will probably ether laugh at you or pull a silly face .
there seems to be a total lack of understanding.
I don't mention my dml panels at audio shows any more as it is the fastest way to end a conversation!!
Steve.
It's probably the same for pro audio as it is for the hifi market .
Try talking to someone in the pro audio business about dml and see what sort of reaction you get.
They will probably ether laugh at you or pull a silly face .
there seems to be a total lack of understanding.
I don't mention my dml panels at audio shows any more as it is the fastest way to end a conversation!!
Steve.
Pixel1.
I'm still surprised that this patent hasn't been used(not that I know of?)
WO2019061685A1 - Full-frequency sounding structure of loudspeaker
- Google Patents
It is very similar to the painters art canvas we have used with good success on this site.
The choice is limited only by our imagination.
As long as the end result is the best possible sound,of course.
Steve.
I'm still surprised that this patent hasn't been used(not that I know of?)
WO2019061685A1 - Full-frequency sounding structure of loudspeaker
- Google Patents
It is very similar to the painters art canvas we have used with good success on this site.
The choice is limited only by our imagination.
As long as the end result is the best possible sound,of course.
Steve.
Attachments
Hi Steve
Aha, 10mm may well be worth a look. I feel an order to Mr Polystyrene on ebay coming on. Any suggestions as to grade? They offer packaging, medium, high, extra high and ultra high densities. Any suggestions as to best density would be welcome.
Also, what's the recommended treatment these days? Is it still a case of lightly sand and apply a couple of coats of dilute PVA?
I also fancy spraying the panels to match the rest of the new build. Is something like Plastikote any good? I have some left over from my driver doping days.
Cheers
Simon
Aha, 10mm may well be worth a look. I feel an order to Mr Polystyrene on ebay coming on. Any suggestions as to grade? They offer packaging, medium, high, extra high and ultra high densities. Any suggestions as to best density would be welcome.
Also, what's the recommended treatment these days? Is it still a case of lightly sand and apply a couple of coats of dilute PVA?
I also fancy spraying the panels to match the rest of the new build. Is something like Plastikote any good? I have some left over from my driver doping days.
Cheers
Simon
Pixel1.
I was listening to the ply panels last night and was not happy with the sound ,very dull and resonant?
I lifted one of the panels while it was playing ,and the sound improved instantly.
So not a good idea to lean panels up against book shelves.
They still sound like ply panels to me though,they still need a lot more work done.
But they will always have the problem of being a heavy panel.
As will all heavy panels,heavy panels will only get you so far,they have limitations.
This is why I concentrate mainly light panels for home use.
Steve.
I was listening to the ply panels last night and was not happy with the sound ,very dull and resonant?
I lifted one of the panels while it was playing ,and the sound improved instantly.
So not a good idea to lean panels up against book shelves.
They still sound like ply panels to me though,they still need a lot more work done.
But they will always have the problem of being a heavy panel.
As will all heavy panels,heavy panels will only get you so far,they have limitations.
This is why I concentrate mainly light panels for home use.
Steve.
Lordtarquin.
I'm not sure about prices of Mr polystyrene but these are a couple of sites I've looked at in the UK.
Handipack Polystyrene Sheet 1200mm x 600mm
Polystyrene Cut to Size
Buying a couple of panels from custompac seem to cost petty much the same as 20 or so with delivery?
One hundred pounds or so, for 20 8x4ft panels sounds good to me,but wouldn't sound so good to my wife!
I have only had 10mm HD in 40cm square test panels with good response.
I originally had the exciter in the centre,but then came up with the idea of cutting one of the sides at an angle and gluing it to go the bottom,the panel now has no parallel sides.
This panel is also painted with vinyl silk ,you could paint it with anything you like as long as you coat it with pva first!
Coatings will change the sound ,so be aware ,as long as you like the sound created?
I would not recommended using doping compounds on eps,the pva is used to help the sound propagate across the panel, and not necessarily to dampen it.
The higher the grade the higher the weight ,but the higher grades should give better HF from the start.
I would always listen to the new grade of panel to see how it sounds, before deciding what to do.
I usually scuff and coat the exciter area with pva (about two inches of so,to strengthen the surface area) do not paint this area ,the paint will probably not be strong enough to hold the exciter.
I have been concentrating mainly on smaller panels on this site so have not been experimenting with the larger eps.
I'm a little involved in recording my LPs at the moment(or trying to) but when I'm finished I will get back to larger eps panels
Steve
I'm not sure about prices of Mr polystyrene but these are a couple of sites I've looked at in the UK.
Handipack Polystyrene Sheet 1200mm x 600mm
Polystyrene Cut to Size
Buying a couple of panels from custompac seem to cost petty much the same as 20 or so with delivery?
One hundred pounds or so, for 20 8x4ft panels sounds good to me,but wouldn't sound so good to my wife!
I have only had 10mm HD in 40cm square test panels with good response.
I originally had the exciter in the centre,but then came up with the idea of cutting one of the sides at an angle and gluing it to go the bottom,the panel now has no parallel sides.
This panel is also painted with vinyl silk ,you could paint it with anything you like as long as you coat it with pva first!
Coatings will change the sound ,so be aware ,as long as you like the sound created?
I would not recommended using doping compounds on eps,the pva is used to help the sound propagate across the panel, and not necessarily to dampen it.
The higher the grade the higher the weight ,but the higher grades should give better HF from the start.
I would always listen to the new grade of panel to see how it sounds, before deciding what to do.
I usually scuff and coat the exciter area with pva (about two inches of so,to strengthen the surface area) do not paint this area ,the paint will probably not be strong enough to hold the exciter.
I have been concentrating mainly on smaller panels on this site so have not been experimenting with the larger eps.
I'm a little involved in recording my LPs at the moment(or trying to) but when I'm finished I will get back to larger eps panels
Steve
Attachments
Last edited:
Some measurements
Thanks Steve..
I've just ordered five sheets of 400 x 600 x 10mm 70 grade EPS for a fiver.
I've also weighed the 3mm poplar ply and 25mm HD panels - 400 x 565mm. The 3mm poplar ply weighs in at 250g, the 25mm EPS at 180g. So 10mm EPS will weigh in at around the 70g mark at most. That's a lot less mass to shift.
The plan is to PVA it, and then spray paint except for the exciter area as you suggest.
I'm getting reliable results using REW and a calibrated UMIK-1 measurement mic. Add in a passive pre 'amp' after the miniDSP 2x4 HD and the ply panels actually sound pretty decent. But I think there's more to be had. With the 15 inch Monacor bass units handling bass duties for the first four octaves the emphasis now needs to be on getting the rest right.
Attached is an illustration of the kind of response I'm getting (1/3 smoothing). I listen to a lot of orchestral music and this benefits from the slight downward FR (about 3db drop overall).
Simon.
Thanks Steve..
I've just ordered five sheets of 400 x 600 x 10mm 70 grade EPS for a fiver.
I've also weighed the 3mm poplar ply and 25mm HD panels - 400 x 565mm. The 3mm poplar ply weighs in at 250g, the 25mm EPS at 180g. So 10mm EPS will weigh in at around the 70g mark at most. That's a lot less mass to shift.
The plan is to PVA it, and then spray paint except for the exciter area as you suggest.
I'm getting reliable results using REW and a calibrated UMIK-1 measurement mic. Add in a passive pre 'amp' after the miniDSP 2x4 HD and the ply panels actually sound pretty decent. But I think there's more to be had. With the 15 inch Monacor bass units handling bass duties for the first four octaves the emphasis now needs to be on getting the rest right.
Attached is an illustration of the kind of response I'm getting (1/3 smoothing). I listen to a lot of orchestral music and this benefits from the slight downward FR (about 3db drop overall).
Simon.
Attachments
Here's the DML panel before any EQ - 1/3 octave smoothing again.
Also, I've included the panel with some EQ - 1/6 octave smoothing this time.
I ran out of PEQ levers to pull to fix a couple of dips and had to do this by tweaking the input PEQ.
My hope is that the EPS panel will be better above 2.5khz and will require less EQing.
Simon.
Also, I've included the panel with some EQ - 1/6 octave smoothing this time.
I ran out of PEQ levers to pull to fix a couple of dips and had to do this by tweaking the input PEQ.
My hope is that the EPS panel will be better above 2.5khz and will require less EQing.
Simon.
Attachments
Lordtarquin.
That is probably the best un EQd response I have seen posted on its site.
Could you please give microphone position and distance from panel.
I recognise the classic response the hump in the midrange and the dip at 10k followed by a peak.
If it was me, I would pull down the response in the midrange a little maybe slanting towards the hf slightly,
Your second plot gets a little lumy in the 200 to 400hz area for some reason ?
The dip and peak at 10k could be corrected on the panel itself(not with the paper strips used for ply.
You would have a response within +- 2.5db.
This would give a good looking response plot ,but it does not tell the whole story.
I usually measure dml by putting on peak hold and movin the microphone around the panel area ,usually about a metre in front.
I then do the same from my seating area ,but this time I move the microphone about one or two feet ether side of me and up and down.
This will give you more of an idea of what is being produced in the room, which can vary from one inch to another.
If Using a single point position response with dml ,you could be correcting something that is not in the room response, and make it worse.
If from your seating position you get a dip ,but at a foot to your right at the same frequently you don't get the same dip ,you might even get a peak! What do you do?
And don't forget it changes as you move up and down a few inches as well.
You might find it interesting if you do this in real time still on peak hold,moving the microphone around the room and watch the frequency response change .
Using this method You should be able to get a more accurate average response of your seating area.
It is not like ordinary speaker where if you move to one side a few inches ,you loose everything above say 5k.
You cannot measure a dml with one point, the frequency and phase changes all the time from the centre of the exciter all the way to the edges of the panel!!!
I can not stress enough that what is produced at one point of a panel will not be the same at another point on the same panel!!
In this way If measured as a whole ,you will know the full output of the panel.
I hope this will be taken into consideration when measuring DMLs.
Steve.
That is probably the best un EQd response I have seen posted on its site.
Could you please give microphone position and distance from panel.
I recognise the classic response the hump in the midrange and the dip at 10k followed by a peak.
If it was me, I would pull down the response in the midrange a little maybe slanting towards the hf slightly,
Your second plot gets a little lumy in the 200 to 400hz area for some reason ?
The dip and peak at 10k could be corrected on the panel itself(not with the paper strips used for ply.
You would have a response within +- 2.5db.
This would give a good looking response plot ,but it does not tell the whole story.
I usually measure dml by putting on peak hold and movin the microphone around the panel area ,usually about a metre in front.
I then do the same from my seating area ,but this time I move the microphone about one or two feet ether side of me and up and down.
This will give you more of an idea of what is being produced in the room, which can vary from one inch to another.
If Using a single point position response with dml ,you could be correcting something that is not in the room response, and make it worse.
If from your seating position you get a dip ,but at a foot to your right at the same frequently you don't get the same dip ,you might even get a peak! What do you do?
And don't forget it changes as you move up and down a few inches as well.
You might find it interesting if you do this in real time still on peak hold,moving the microphone around the room and watch the frequency response change .
Using this method You should be able to get a more accurate average response of your seating area.
It is not like ordinary speaker where if you move to one side a few inches ,you loose everything above say 5k.
You cannot measure a dml with one point, the frequency and phase changes all the time from the centre of the exciter all the way to the edges of the panel!!!
I can not stress enough that what is produced at one point of a panel will not be the same at another point on the same panel!!
In this way If measured as a whole ,you will know the full output of the panel.
I hope this will be taken into consideration when measuring DMLs.
Steve.
Thanks Steve, very helpful indeed.
The unEQd response seems pretty consistent whatever I do. I've tried measuring near field from about 1m and also from my listening position. I usually stick the mic on my tripod to try to get some consistency, so it will be easy to get some controlled results from different positions.
As I understand it, the usual strategy is supposed to be to measure drivers near field or where room effects are minimal, use output level EQ to fix driver response and then use input EQ to correct for room response.
With DMLs and especially OB bass, room interactions are a critical part of the setup. With the miniDSP 2x4 HD I have 10 EQ bands per output driver (4) and 10 EQ bands per channel (2). I've played around with 1/12th and 1/6th octave smoothing when doing the EQ. 1/3 smoothing is a little too crude.
I'm glad you mentioned phase - it's all over the place! I had planned to have a go with linear phase crossovers with the miniDSP, but I've still to get to grips with it - not enough taps are available and I cannot yet work out how to configure it (I've used RePhase).
I'll give the mic position thing a go - probably on Thursday when the mini heatwave is over.
Cheers
Simon
The unEQd response seems pretty consistent whatever I do. I've tried measuring near field from about 1m and also from my listening position. I usually stick the mic on my tripod to try to get some consistency, so it will be easy to get some controlled results from different positions.
As I understand it, the usual strategy is supposed to be to measure drivers near field or where room effects are minimal, use output level EQ to fix driver response and then use input EQ to correct for room response.
With DMLs and especially OB bass, room interactions are a critical part of the setup. With the miniDSP 2x4 HD I have 10 EQ bands per output driver (4) and 10 EQ bands per channel (2). I've played around with 1/12th and 1/6th octave smoothing when doing the EQ. 1/3 smoothing is a little too crude.
I'm glad you mentioned phase - it's all over the place! I had planned to have a go with linear phase crossovers with the miniDSP, but I've still to get to grips with it - not enough taps are available and I cannot yet work out how to configure it (I've used RePhase).
I'll give the mic position thing a go - probably on Thursday when the mini heatwave is over.
Cheers
Simon
Lordtarquin.
Yes you are quite correct,the usual strategy for measuring cone or dome drivers is to measure the sweet spot directly in front of the units.
If you moved the microphone to the left of right a small distance the response would be appalling.
When you take a measurement in front of the exciter area on a dml panel ,you area measuring the sweet spot produced by the primary output of the exciter,which is exactly the same as measuring a standard drive unit such a tweeter ,midrange,and bass unit ,but all rolled into one!
The HF will beam from this area.
What happens after this primary output is what sets off the dml on the rest of the panel.
The phase I was talking about ,was the phase across the panel,which could probably be about 50% out of phase with itself and varying between these two states.
This is why dml has been described as being chaotic in nature.
If you move a microphone, say at about 2inches distance, across a large dml panel ,you will see the response varying greatly with large dips and peaks.
It is the combination of the whole that fills the room with sound,this also includes the response from the back and the sides of the panel also.
You cannot measure one point on a panel and say this is the response of that panel.
On my smaller panels ,they maybe a different story ,as they are becoming more of a point source?
Measuring a dml is not as easy as it seems,using standard measurements.
Most dml that I have measured from say 2inches in front of the exciter area will give a really good response,but sometimes, the rest of the panel response(DML) can be appalling!!!
I could go on?
But this subject is vast.
I stick to what I hear and measure in my room,it's a lot easier that way.
by the way the dip and peak in the hf response ,I believe is a resonance and distortion(phasing) in the coil area,you can level it ,but really you need to get rid of it,this can cause a harsh sound.
Steve.
Last edited: