I was looking at the MiniDSP but I just ended up ordering the Dayton DSPB with the expansion/programming boards. Half the price of the MiniDSP and seems to have far more flexibility, and you don't have to buy the different DSP software modules. As long as your're good with 2.1 output it seems to be the far better value. I am just looking to do some eq work and a 2 way crossover between my panels and sub.
You might look into these Class D amps with built in Analog Devices ADAU-1701 (same as on basic miniDSP) and use free SigmaStudio suite from AD to program the crossovers and filters.
Dayton Audio DSPB-250 2x50W Class D Audio Amplifier Board with DSP
Dayton Audio DSPB-250 2x50W Class D Audio Amplifier Board with DSP
Same system as the Dayton DSPB stuff, just integrated into a chip amp board. Pretty nice if you want to run class D. I personally prefer class AB stuff so I am using modified TDA7377 boards. Although the Allo Volt+ boards get great marks on audiosciencereview for SQ so I may try those soon.
Yes this is the base of the build I'm working on. I've heard and seen really great things.
I'm trying to get my head around what is happening to your panels.
What is happening when you are playing music ,does it buzz , does it sound bad ?
Are you saying that the test tones are setting up resonances in the canvas and exciter,plus obviously the ply ?
It's making me wonder how well an electrostatic panel would handle such test tones ?
I must admit I never thought of using test tones on any of my panels.
In the past before I came across dml, I did look into thin film as a drive material.
But the resonances set up in thin film is even worse, it was a nightmare.
It's pretty ironic that I am now using dml panels that use resonances to function properly .
At the end of the day the canvas panel is a drum , but hopefully a de-tuned drum?
I don't remember them going into this in the patent.
Which would of been handy.
Although they did give panel tensions .
Not sure if this would cure the problem though ?
Steve.
OK: more thoughts.
First using different fabrics instead of canvas. Once they are framed you submerge them in water and let it dry: they will shrink in diverse degrees and increase tension.
Second trying to find the materials used in drums and make an open backed box, like a drum, only more shallow. That OB principle could be tried on the canvas panel. Has anyone tried that?
First using different fabrics instead of canvas. Once they are framed you submerge them in water and let it dry: they will shrink in diverse degrees and increase tension.
Second trying to find the materials used in drums and make an open backed box, like a drum, only more shallow. That OB principle could be tried on the canvas panel. Has anyone tried that?
Carlmart.
The problem with increasing tension on the panel is the same as a drum.
The tighter the drum the higher the drum frequency, which could work if you are not interested in the LF.
But this would raise the drum,panel, resonance.
What affect this would have on the panel sound I'm not sure.
It could start the panel making drumming sounds higher up in frequency?
I guess you won't know until you try.
Steve.
The problem with increasing tension on the panel is the same as a drum.
The tighter the drum the higher the drum frequency, which could work if you are not interested in the LF.
But this would raise the drum,panel, resonance.
What affect this would have on the panel sound I'm not sure.
It could start the panel making drumming sounds higher up in frequency?
I guess you won't know until you try.
Steve.
Is there a way to open sweep in REW?
I converted the mp4 file to wav, but REW does not seem to recognize it or accept it.
Carlmart.
The problem with deepening the panel sides ,would be the same as on an open baffle panel.
OK ish on a bass unit ,but would have the affect of putting the midrange in a tunnel, with all the associated problems.
I don't know how or what tension they apply to the canvas panel but it seems about right for 40hz.
But for the sort of volume levels I use the panels for , I would not use them below about 120hz probably.
I have in the past just played my various panels at very realistic levels and at full range ,and slowly reduced the low end until the problem hopefully stops.
We must not forget that these are a full range panels(whatever that is)and not a sub woofer.
Steve.
The problem with deepening the panel sides ,would be the same as on an open baffle panel.
OK ish on a bass unit ,but would have the affect of putting the midrange in a tunnel, with all the associated problems.
I don't know how or what tension they apply to the canvas panel but it seems about right for 40hz.
But for the sort of volume levels I use the panels for , I would not use them below about 120hz probably.
I have in the past just played my various panels at very realistic levels and at full range ,and slowly reduced the low end until the problem hopefully stops.
We must not forget that these are a full range panels(whatever that is)and not a sub woofer.
Steve.
Steve
As I use an LR24 XO @ 300hz, the issue largely disappears. There's nothing obvious when playing music. Organ works may be a challenge though!
I have, however, tried something else. I have cut down some of the ultra high density EPS to 30x40cm and secured it to one of the canvas panels with canvas removed (i.e. using just the frame. I have secured it at each corner and at intervals on the sides to about 6mm of foamed close cell foam (foam stuck to the frame then the panel stuck to the foam). It's very similar to the method described by DMLBES a few thousand posts ago and in the other fora.
The results are extremely encouraging. I get none of the spurious noises I have experienced with everything else I've tried. I plan to try a pair of stacked panels per side with the 4 ohm exciters wired in series. This will give a larger radiating area and more power handling. In theory, mutual driver coupling MAY give a bit of a midrange boost, but I don't know whether this works for panel speakers in the same was as it does does conventional coned drivers.
Simon
I know I've posted this in some thread on this site, but it seems timely:
Lots of variations available.
Seems simple and straight forward for a DML.
Readily available.
Metal or plastic frame.
Equal tension across surface of the drum head.
I'd think a drum head (usually some kind of plastic) would provide a good surface on which to attach an exciter.
Not certain what the circular shape would do.
Steve -- re:
Why "de-tuned"?
-- Andreas
See: Base drum head
Lots of variations available.
Seems simple and straight forward for a DML.
Readily available.
Metal or plastic frame.
Equal tension across surface of the drum head.
I'd think a drum head (usually some kind of plastic) would provide a good surface on which to attach an exciter.
Not certain what the circular shape would do.
Steve -- re:
Why "de-tuned"?
-- Andreas
Attachments
I'm no expert but I notice, many times it is mentioned the best material is both light and rigid. A drum head is light but not rigid. Drum head surface oscillates when struck, waves roll across a drum surface, where as DML's entire flat surface should vibrate in a transverse direction without bending. I would think using the drum head would be a good edge of frame to mount a plywood or EPS sheet on but not as good for the transduceing surface it's self. Any opinions?
normgr00
I'm minded to agree. When trying the canvas panels with a bit of ply glued in place for the exciter, I could easily see some very odd oscillations occurring. However, I have had more success using the canvas frame to mount some ultra high density EPS on to. Of the half a dozen different panels I've tried to date, my 30x40cm panels using this approach are giving me the best sound to date. I may try doubling up to 2 panels per side, but this can wait for a bit.
I should add that I like a whole range of different music genres, but for me, a speaker MUST be able to handle large orchestral pieces (think Mahler, for example), and my DML / OB bass hybrid setup has given me more of what I'm after than any speakers I've owned to date.
I'm minded to agree. When trying the canvas panels with a bit of ply glued in place for the exciter, I could easily see some very odd oscillations occurring. However, I have had more success using the canvas frame to mount some ultra high density EPS on to. Of the half a dozen different panels I've tried to date, my 30x40cm panels using this approach are giving me the best sound to date. I may try doubling up to 2 panels per side, but this can wait for a bit.
I should add that I like a whole range of different music genres, but for me, a speaker MUST be able to handle large orchestral pieces (think Mahler, for example), and my DML / OB bass hybrid setup has given me more of what I'm after than any speakers I've owned to date.
I'm curious on how to assemble the EPS on the canvas frame.
Guessing the frame provides some rigidity to the EPS, which probably alters the damping. What about gluing wooden pieces to the four sides, on the inside of from outside, not necessarily meeting at the corners, or even rounding the corners as some have tried?
Best of both worlds?
Guessing the frame provides some rigidity to the EPS, which probably alters the damping. What about gluing wooden pieces to the four sides, on the inside of from outside, not necessarily meeting at the corners, or even rounding the corners as some have tried?
Best of both worlds?
No. Its a raw board, and out of the box it's programmed to be a 2 way adjustable crossover. You buy the RCA hat board and the programming module and then you have the ability to program the DSP chip to do anything you need, and the RCA ins and outs if you don't want to make your own running from the board headers. Then you can put it in whatever enclosure you want. It's definitely a DIY solution but in the end it's way more flexible than the MiniDSP at half the price.
As for the canvas stuff, way back in this thread there were a few guys getting good results of tightening their canvases by using gesso or stain blocking primer like Killz. You want to start with a quality canvas, then do a couple layers of gesso, which will tighten the canvas as it dries, and stiffen it a bit. You may also need to shim between the frame and the canvas on the inner edges. They also used small wafers of balsa glued to the back of the canvas to attach the exciter to. Results were decent but I'm assuming it doesn't take too long with the vibrations and the weight of the exciter to stretch out the canvas a bit and you're back to where you started.