Celestion CDX1-1425 deviations

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
diyAudio Chief Moderator
Joined 2002
Paid Member
Hello all

Does anybody have experience on what kind of frequency response tolerances I must expect from these drivers?

I bought them directly from a reputable UK stockist. They look unused indeed but maybe they had a rough trip, the (+) terminals were beaten a bit on both, I don't know if they received a side blow.

I run impedance curve tests first and one driver's shape looked weird. Their unmounted frequency plots were too different as well. I took them apart and re-assembled them carefully to best close impedance plots I could before mounted on horns (Z plots before & after horn mounted attached).

The orientation of the diaphragm sub-assembly proved very influential to the impedance curves. There is no form of mechanical orientation aid. Only two centering teeth at the rim. The diaphragm chassis can turn like a sports watch bezel to where decided. So I had to look on advertisement photographs for how it should point regarding the frame.

The four self tapping screws that fix the magnet and motor to the plastic cross frame do not inspire confidence on both units. Although they don't allow for visible gaps at the mating, they don't screw to a stop either. Maybe one or two did initially but the plastic threads loosened up easily even when being careful.

Anyway these are the responses I get from them when mounted on FaitalPro STH100 horns. Its just quick close up measuring in very low SPL with no baffle, mouths sitting at the edge of a desk. But indicative enough to check the matching. Any expert comments?

Thanx
 

Attachments

  • Mounted.JPG
    Mounted.JPG
    262.7 KB · Views: 791
  • FRvsFR.png
    FRvsFR.png
    29.4 KB · Views: 710
  • Z_RedSansHorn.png
    Z_RedSansHorn.png
    7.6 KB · Views: 664
  • Z_BlueSansHorn.png
    Z_BlueSansHorn.png
    7.6 KB · Views: 656
  • Z_Blue_Mounted.png
    Z_Blue_Mounted.png
    7.3 KB · Views: 214
  • Z_Red_Mounted.png
    Z_Red_Mounted.png
    7.3 KB · Views: 634
I belive your drivers are very fine and matched as well as can be expected. Thank you for showing these measurements, I have been interrested in these drivers for a while. nice output all the way to 20KHz, I dont like the peak at 1KHz though. I expect the two last impedance measurements are with the horn put on the drivers?
Do you have other horns to try them onto?
 
diyAudio Chief Moderator
Joined 2002
Paid Member
I belive your drivers are very fine and matched as well as can be expected. Thank you for showing these measurements, I have been interrested in these drivers for a while. nice output all the way to 20KHz, I dont like the peak at 1KHz though. I expect the two last impedance measurements are with the horn put on the drivers?
Do you have other horns to try them onto?

I hope so because I had to tamper with them. Yes the two last ones are when horn loaded. No other horns around for tests right now. Mainly because only the B&C ME10 would also fit in the narrow tower speaker's baffle and the FaitalPro is the only metallic one I could find that fits, but with a bit of more care in the cutting. But I have non horn mounted close up frequency chart if it tells you anything about the 1kHz thing when raw.
 

Attachments

  • CDX1-1425_Near_A-B.png
    CDX1-1425_Near_A-B.png
    30.6 KB · Views: 223
diyAudio Chief Moderator
Joined 2002
Paid Member
I like Celestion CD's. Dollar for dollar, they're the best in business IMO. Your response is as smooth as any CD on the market which would make for an excellent top end down to 1.5khz or so.

I plan to replace the now dome tweeters for mating my PHL1220s with those. So at 2.5kHz but better at 3kHz if able. That Faital short elliptical Tractrix waveguide looks like taking good control just about there. I moved the listening position at 4.4 meters from the face of the speakers and the domes don't cut through the room sound and its HF absorption as good as they could up to 3 meters anymore.
 
diyAudio Chief Moderator
Joined 2002
Paid Member
POOH thanks for the confirmation because I thought I might have tampered wrongly with them. That gradual 0.5dB to 1dB last octave output difference I will have to re-evaluate after the padding down and I can boost the weaker one with a small capacitor across a series resistor if it persists enough.

What is your opinion about I devise some modification for the magnet to frame assembly? Like drilling the chassis brackets for long screws with nuts? Maybe the deep threading in the plastic that loosened does not guarantee enough or alike screws pressure between the units and makes for the last octave output differences?
 
The 1730 wins on THD and threshold level of compression below 3kHz I suppose.

I like it because it does go lower and it has better rendition of tone and organic realistic sound. It needs less contour on the top end too. A really crazy good treble driver. The 1425 is no slouch though - I like to crossover around 3K and the 1425 is a little bit on the metallic shimmer side where the 1730 is very much real - either one in the right set up should be SOTA if you value realism
 
diyAudio Chief Moderator
Joined 2002
Paid Member
I like it because it does go lower and it has better rendition of tone and organic realistic sound. It needs less contour on the top end too. A really crazy good treble driver. The 1425 is no slouch though - I like to crossover around 3K and the 1425 is a little bit on the metallic shimmer side where the 1730 is very much real - either one in the right set up should be SOTA if you value realism
I do have only DIY FET or tubes preamps and power amps which are polite on the highs so no problemo. Thanks for your valuable input as you have hands on experience with the specific CD + horn I just got. :up:
 
Salas would it be posible for you to make a few on/off aksis measurements on your Celestion/Faital combo?
I am also very interested in the HF108. Does anybody know what is the difference on that one compared to HF108R model?
HF108 was tested in voicecoil magazine, I think It had much distortion around 9-10KHz, and that have made me look for other alternatives. Right now I am also considering Celestion CDX1-1730 and B&C DE-250 I like its low resonance frequence.
 
diyAudio Chief Moderator
Joined 2002
Paid Member
Maybe in the next few days I will have the opportunity to make more meaningful measurements of my combo. About the other CDs you ask I don't know much. From B&C I had used DE12, DE16 and DE38 on Eighteen Sound XT120 horns. I much preferred the DE12 cut at 3kHz on that horn when it had to be with a minimal 12dB electrical passive. DE16 & DE38 were wilder to control on a small horn.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.