B&C DE25-8 CD/Stereolab 400Hz horn - diyAudio
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Old 7th January 2013, 07:37 PM   #1
Hylle is offline Hylle  Denmark
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Default B&C DE25-8 CD/Stereolab 400Hz horn

This is my first experince with CD and horn for Hifi use with passive cross over. I need to damp the CD/horn a lot to make it fit a 90dB 8" woofer. I experince that when the signal is low into the CD, when lots of resistance is added to make the soundpressure low to meat the 8" woofer, then I get a deap sugout around 3500Hz, and it also happens with a very low input signal when you connect directly to the CD.
When the input signal is raised the sugout disapears.
I can see on the impedance responce there is also small low drop around 3500Hz, so something is going on there.

Have anybody tryed the same, I know Earl Geddes have used this driver quite a bit.
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Old 7th January 2013, 07:42 PM   #2
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use Autotransformer instead of that much of resistors to attenuate and -d function
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Old 8th January 2013, 06:41 AM   #3
Hylle is offline Hylle  Denmark
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No, of cause it is not the best to pad down so much sensitivity with resistors. But I guess it is some sort of meassuring problem, I belive frequence responce should not be level dependent.
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Old 8th January 2013, 01:38 PM   #4
bwaslo is offline bwaslo  United States
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Your crossover 's frequency response will change when you add a series resistance. An L-Pad would work better, though still not perfect.
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Old 8th January 2013, 02:52 PM   #5
gedlee is offline gedlee  United States
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Quote:
Originally Posted by Hylle View Post
Have anybody tryed the same, I know Earl Geddes have used this driver quite a bit.
The DE25 is obsolete and hasn't been around for years. It was replaced by the DE250.

Resistor padding works fine for me, but designing the HP filter for a horn is not trivial. In any case, the response should not be dependent on the signal level of something is wrong.
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Old 8th January 2013, 03:06 PM   #6
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Maybe the diaphragm is out of alignment?
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Old 13th January 2013, 02:20 PM   #7
Hylle is offline Hylle  Denmark
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I solved my problem, this tendency with a sugout around 3500 hz at very low levels, was removed, when I disassembled the compressiondriver. I could not see anything wrong but a cleared the magneticgab with a peace of paper and after assembling the driver, it works fine.
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Old 13th January 2013, 02:24 PM   #8
Hylle is offline Hylle  Denmark
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I have been playing with the passive crossover now. The driver/horn drops of quicly after 10Khz, I have tryend to bridge the series resistanve with a capacitor but still frequences above 10KHz is not raised, how can that be?
The driver have a rising impedance at higher frequences, But I guess that would not be the problem. Is there anything to do about it?
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Old 13th January 2013, 10:34 PM   #9
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Well, using a compensation filter like that can't do nothing. Post more data. You measurement, where you took it from, your filter values, etc.
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Old 7th March 2013, 10:07 AM   #10
Hylle is offline Hylle  Denmark
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I feel I have made a quite good speaker with this horn/compressiondriver B&C DE25-8 but I have a harshness on especially whomen voices I can get ride off, and I belive it is comming form the drivers. Have anyone experinced the same with B&C drivers? Are there other drivers that will not do that?
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