Sorry i’ve missed to describe the exciters.
They are modified drivers from tectonic. I needed an exciter that had close to 10 mm xmax and strong enough to drive the panel in piston mode. I couldn’t find a regular exciter with this specification. The modification is easy to do. The chassi is made of plastic.
Attachments
That’s a bit clearer now. I was thinking of one panel connected in phase and the with phase reversed, but you said pair of panels. Can you give a reference that discusses this technique?
10mm p-p from the data sheet. It’s stated as x mech max. Which most likely means its not perfectly linear in the whole range.
Thanks. To be clear, I wasn't criticising you for not stating it, only that I expected that it had been stated, and that I was most likely asking for it again.
The BMR voice coil is so thin it will not hold up the magnets weight therefore you must use a frame and spine to hold the magnets weight in place. Although exciters were designed to hold the magnets weight they will benefit from using a frame and spine especially with the larger/heavier exciters.
This is the reason why I say you should build it like a BMR driver with a frame and a spine to hold the magnet in place with some sort of surround material to hold the diaphragm in place as everything will be supported.
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Alvipet,
Very interesting, I will have to try it! Though I am still not yet sure I understand the theory behind the measurement, it's sure easy to try.
Can you describe the panel in your measurements? Thickness(es), materials?
Thanks,
Eric
2 good points in this spec : the resistance (7Ohms) and the inductance (0.05mH) compare to more usual 4 Ohm, 0.1mH at the best so the current and then the force will be maintained further in the frequency range. BL is good not excellent
Good also to have holes at the top of the voice coil to allow the air escaping hopefully with no or little noise.
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Just normal cardboard with an extra layer of corrugated cardboard, 3 exciters used 2 cheap 25mm wired in series and one 32mm in parrel , ribbon crossed at 2400khz , cardboard supported both sides, I cut a slot the length of the two 2"X2" for the cardboard to be slotted down, see my video I've just posted on here, phone recording but you get the idea.Yes, please describe what you did to prepare the stiff cardboard for the panel? And, anything and everything relevant.
Speaker thickness about 40 mm, materials - plywood, honeycomb radiating membrane. Here they are
Sorry, I couldn't reply earlier. Only just now the guests left. Thank you very much for the Karavashkin link. Oh, I made a mistake with the word epoxy. I was thinking about the stabilizing impregnating composition based on polyurethane primers and varnishes covering surface layers. So, what might be the weight of the honeycomb panel after the treatment of polyurethane primers and varnishes both surface layers. An approximate value is enough. Oh, what might be the thickness of that membrane?
I have gone back to read Henry Azima's thoughts again, now with a different outlook, that is, after reading Herger's patents and Gobel's patent (from @Sandasnickaren link), I have a sudden feeling that I'd build a fully enclosed DM speaker, sometime in the late spring or summer. If it's going to be omnidirectional in the far field, I'd be quite content. If it stays between 50Hz to 15kHz, it'd be quite alright. I don't think my hearing would reach that much, but my wife may hear better. True, I've studied the patents deeply. I have some more to read, though.
I have given the links and translated some excerpts for others here to study them too, that is, if they want to.
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Thank you for the link Alvipet.
Are the bass from the panels?
I was wondering about the device below? To make my question more clear : I am wondering about which sub to help panels and I have crossed the "Ripole" (2 woofers oriented like that and load by a slot). Having them in separated boxes may help in trimming the system?
Other questions : about the way to record. You use here a Tascam05.
How is the sound level in the room? I know a bit difficult to answer... low, high as usual, very high?
Have you experience with other recorders (Zoom H1n for example)?
Are there some rules to get a record similar to the sound in the room?
Christian
For monitors as in the video at the link, the weight of the membrane is within 50-70 grams, the thickness is 3 mm
Sorry, I didn't reply earlier. Too many guests at home.
Can you please post few images? And dimensions, etc?
Alvipet,
When I asked for the panel thickness before you replied 40 mm, which seemed rather thick! But I guess you thought I meant the whole speaker.
Actually, what I was trying to get at was enough information to take a reasonable guess at what the coincidence frequency "should" be, based on the details of construction of the panel, and their thicknesses, then I could compare that to your measured result of 1.7 kHz
So far, what I understand is that the whole panel is 3 mm, and is constructed of "plywood" with a honeycomb core, is that correct?
Could you share more details about the construction?
Perhaps the honeycomb core is nomex? How thick?
And what is the thickness of the outer layers of wood, and how many plies are in each of them?
I understand if this is more detail than you want to share....
Thanks
Eric
On video panels work together with PPD subs. They are not quite "Repole". You can read about them here . On their own, the panels provide a linear frequency response down to 50 Hz.
The SPL level in the room is around 75-80 dB during recording. Besides Taskam 05, I also sometimes use the Zoom H4n. But in comparison with Taskam, it records in low frequencies not so thoroughly. I am not an expert in sound recording and therefore I can hardly give you exhaustive advice in this matter.)