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-   -   Quad 63 (and later) Delay Line Inductors (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors.html)

bolserst 3rd July 2021 02:50 AM

@jan.didden,
Congrats on getting your DD amp up and running! :up:
Looking forward to whatever details you can share about the circuit once you have all the bugs ironed out.

Quote:

Originally Posted by jan.didden (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors-post6694729.html#post6694729)
is that natural rolloff caused by the xformers and xover parts?

No, the natural rolloff is due to the under-damped 2nd order HP mechanical response created by the diaphragm resonance. With constant drive from the amplifier(or amplifier + transformer), the diaphragm excursion will not increase below resonance. (This is similar in concept to a dynamic woofer in sealed box)

If you take a near field measurement you should see a LF response similar to those shown in the attached images in this post: Quad esl resonance damping: how?

bolserst 3rd July 2021 02:51 AM

Quote:

Originally Posted by jan.didden (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors-post6682613.html#post6682613)
Yes there seems to be a difference. In this case, I applied the probe EQ after the measurement rather than to the source level, I have to see if that has introduced an error.

Not that this has any bearing on your final results now that you are EQing based on microphone measurements, but just curious if you ever figured out why measurements were different between the setups? One thing I had meant to ask, did you try swapping the connections to the differential probe? Ideally if there is no common mode contamination to the measurement you should get the same response but with opposite phase. I recall having issues with this when I was measuring the response of A SoundLab A-1 interface for different setting of the MID and LF controls. Eventually I had to borrow a Jensen Input transformer to get rid of the problem.
Full Range Electrostatic Question

bolserst 3rd July 2021 03:03 AM

1 Attachment(s)
Quote:

Originally Posted by bolserst (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors-post6678732.html#post6678732)
… I plan to wind up some inductors this weekend that more closely match the winding geometry(ie starting from near zero radius) and see if I can get a better estimate of the coupling factors to use.

Quote:

Originally Posted by Hans Polak (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors-post6671328.html#post6671328)
Here is the version when cross-coupling the inductors with K=0.3 for the adjacent and K=0.1 for those one place further.

I did finally get the time to wind up some inductors more similar to the size and proportions of the actual delay-line inductors.
The new measurements show that the original estimate was not too far off.

New coupling factor estimates are:
K=0.25 (adjacent inductors)
K=0.05 (inductors one place further down the line)

jan.didden 3rd July 2021 06:08 AM

Quote:

Originally Posted by bolserst (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors-post6708512.html#post6708512)
Not that this has any bearing on your final results now that you are EQing based on microphone measurements, but just curious if you ever figured out why measurements were different between the setups? One thing I had meant to ask, did you try swapping the connections to the differential probe? Ideally if there is no common mode contamination to the measurement you should get the same response but with opposite phase. I recall having issues with this when I was measuring the response of A SoundLab A-1 interface for different setting of the MID and LF controls. Eventually I had to borrow a Jensen Input transformer to get rid of the problem.
Full Range Electrostatic Question

I never followed that up unfortunately. I did notice that the amplifier I used in the test (a 200W class D) did not have a very flat response when driving the '63, so that may have been a factor.

Jan

jan.didden 3rd July 2021 06:11 AM

Quote:

Originally Posted by bolserst (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors-post6708511.html#post6708511)
@jan.didden,
Congrats on getting your DD amp up and running! :up:
Looking forward to whatever details you can share about the circuit once you have all the bugs ironed out.


No, the natural rolloff is due to the under-damped 2nd order HP mechanical response created by the diaphragm resonance. With constant drive from the amplifier(or amplifier + transformer), the diaphragm excursion will not increase below resonance. (This is similar in concept to a dynamic woofer in sealed box)

If you take a near field measurement you should see a LF response similar to those shown in the attached images in this post: Quad esl resonance damping: how?

Thanks, got it.

Jan

Hans Polak 5th July 2021 04:16 PM

1 Attachment(s)
Quote:

Originally Posted by bolserst (https://www.diyaudio.com/forums/planars-and-exotics/338927-quad-63-delay-line-inductors-post6708519.html#post6708519)
I did finally get the time to wind up some inductors more similar to the size and proportions of the actual delay-line inductors.
The new measurements show that the original estimate was not too far off.

New coupling factor estimates are:
K=0.25 (adjacent inductors)
K=0.05 (inductors one place further down the line)

Hi Steve,

Great to have these values confirmed.
I've adjusted the model to these two values, but as expected, it makes very little difference.
Even making the second coupling factor K=0 does very little.
But nonetheless, your figures are exact and the model is updated.

Hans
.

mkc 20th August 2021 07:45 AM

Hi Jan,

Any progress with the DD drive?

Mogens

jan.didden 20th August 2021 07:46 AM

I did, but then got sidetracked with an upcoming move of my household and my lab. Sometimes life interferes with your plans ...

Jan

mkc 20th August 2021 08:22 AM

Yes, it's not always easy to find time for the fun stuff. I was just curious.

I'm also in the process of rebuilding house. Has taken far longer than it should... oh. well.

Mogens


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