Thanks! I'll see what I can dig up when I'm at the shop tomorrow.
That would be this design. Fun little project I did last summer. https://www.diyaudio.com/community/threads/portable-battery-powered-meh-build.415747/
Gen2 adapter for Celestion CDX1-1720 is available.
A400G2
Celestion CDX1-1720/T520-1720 vs 18Sound ND3T/36-EXT
~5 ms window
Celestion CDX1-1720/T520-1720 vs 18Sound ND3T/36-EXT
~5 ms window
BTW, below is a DFM-2535 from the new batch (the Group Buy). Maybe a QC issue, I will check more of them later -
(I accidentally deleted data for the old one, so I don't have a direct comparison. This is for a bit higher input voltage than the previous picture.)
(I accidentally deleted data for the old one, so I don't have a direct comparison. This is for a bit higher input voltage than the previous picture.)
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That seemst correspond to this impedance variation, see this post:
Post in thread 'Group Buy: Peerless by Tympahny DFM-2535R00-08'
Impedance variations of 6 drivers I received yesterday.
For better results some adjustments/recentering of membranes seems to be needed.
Measured on the desk, without a horn/waveguide.
@sheeple, thanks for organising this groupbuy 🙂
For better results some adjustments/recentering of membranes seems to be needed.
Measured on the desk, without a horn/waveguide.
@sheeple, thanks for organising this groupbuy 🙂
Yeah, now only figure out what it is....
Could be the centering of the diaphragm. What else?
Could be the centering of the diaphragm. What else?
Open one that you know is good and one with the dip and look for differences. Check if all of the screws on back chamber are tight.
If there isn't any visual difference, play some music for a few days and remeasure.
If there isn't any visual difference, play some music for a few days and remeasure.
The black is the old one, the blue is one of the new ones -
I have it opened at the bench. All attemps so far always end up with the same impedance curve. Almost like something is just different.
Shouldn't there be a shim between the diaphragm assembly and the top plate?
I have it opened at the bench. All attemps so far always end up with the same impedance curve. Almost like something is just different.
Shouldn't there be a shim between the diaphragm assembly and the top plate?
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That would be unfortunate. Can you see physical differences?
2015 impedance chart: https://www.electrocarts.in/wp-cont...8-1-Compression-Horn-Driver-24-Bolt-8-Ohm.pdf
2018 impedance chart: https://audioxpress.com/article/peerless-by-tymphany-dfm-2535r00-08-compression-driver
impedance chart at peerless website: https://products.peerless-audio.com/transducer/438
2015 impedance chart: https://www.electrocarts.in/wp-cont...8-1-Compression-Horn-Driver-24-Bolt-8-Ohm.pdf
2018 impedance chart: https://audioxpress.com/article/peerless-by-tymphany-dfm-2535r00-08-compression-driver
impedance chart at peerless website: https://products.peerless-audio.com/transducer/438
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It seems something is different with the new diaphragms. They look identical though (the old one seems to be a ~0.2 g heavier).
I'm able to take the old diaphragm and put it into a new driver and get a nice smooth impedance curve (black), repeatedly. Not so the other way around (blue), no matter what I do.
But maybe I was just lucky before, really hard to say...
The only difference I'm able to spot visually is that the perforation of the suspension is positioned a tiny bit differently relative to the terminals...
I'm able to take the old diaphragm and put it into a new driver and get a nice smooth impedance curve (black), repeatedly. Not so the other way around (blue), no matter what I do.
But maybe I was just lucky before, really hard to say...
The only difference I'm able to spot visually is that the perforation of the suspension is positioned a tiny bit differently relative to the terminals...
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in your first comparison, impedance peak of the old one is higher in frequency, in your second, lower than the new ones. how comes?
if that's the case this is evidence that construction has changed. Although my question is if the actual diapragm is of differenz weight and not the assambly etc. pp. ...
if that's the case this is evidence that construction has changed. Although my question is if the actual diapragm is of differenz weight and not the assambly etc. pp. ...
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