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Not sure how to cure your ripples, Not even sure how to read your graphs, Looks like your having fun though. Have you tried that PCD program yet, I'm telling ya it's the cats meow when designing crossovers. Just drop in your ZMA files from your Dats sweeps and play with the tumbler buttons. couldn't be any easier.
Mike
For prototyping I use 8 ohm L pads to dial in a resistance 0 to 8 , 8 to 25 and 0 to 25 ohms. I suggest you start your sweeps a bit higher say 500 or 1kHz. I don't know the low freq limits for your driver.
Tumber Buttons ?? Tell us what they do, or what they suggest.
Don
You're right there, CD...having fun and learning a bunch. Don is generous with his time and knowledge! I did download the PCD thing. Haven't gotten too far with it yet - I did manage to import the DATS data and my FR curves from HolmImpulse... but didn't get any further than that yet. It's a big, complex spreadsheet and a little daunting at first. I need a couple of hours to read the directions and play around with it.Quote:
Originally Posted by cradeldorf
Thanks, Don. Yeah, I used an LPAD to get close to the R12 number, then started plugging in resistors. I wish there was a variable capacitor/trimmer that worked in the uF range! :biggrin2:Quote:
Originally Posted by donaldpatten
Mike
esodesign requested you compare the N1500A clone to the time delay filter . See post 27
I believe the ripples are the mechanical loading caused by the horn.
Don
Mike
Please check the horn/driver frequency peak.
I want to make a filter to knock down the peak.
It looks like 1.8 or 1.9 kHz. If you can put a marker on your curve you may not have to retest
I have two Cap sub boxes:
Heath kit: 0.0022 uF to 0.22
DIY : 0.33 to 15uF in twelve EIA steps, built in a round CD box.
Have you listened to your new baby?
Don
They are up down buttons, you just click through the different cap sizes and Inductor sizes and watch the graph to show you how the crossover is gonna perform.Quote:
Originally Posted by donaldpatten
I think Don is awesome too.Quote:
Originally Posted by Alien_Shore
Here is the scope of the chirp pattern using the N1500A clone:Quote:
Originally Posted by donaldpatten
https://live.staticflickr.com/65535/...12ffb3d0_b.jpg
Do you think that the signal that dips right after the main pulse is due to polarity? I think when you combine a 1st order filter with a 2nd order filter, you're supposed to reverse polarity, (which I don't think I did)...
Don, if you mean on the barefoot impedance sweep, the peak of 18.20 ohms occurs at 1836 Hz.Quote:
Originally Posted by donaldpatten
Yes, I've been doing some listening tests. The TD filter improved things quite a bit, even with no enclosure whatsoever. The N1500A clone sounds even better, but it's an unfair comparison, since it has the integrated LPAD, etc. I have the parts on order to build the HF filter you designed out for me. They should be here by Tuesday and I'll get it going, then I can test apples to apples.
Mike
It is getting deep around here.Thank you
Re the N1500A chirp traces : the woofer pulse, is 1st followed by the horn pulse about 400 microseconds later.
The freq resp.curves show the polarity, phasing, and is what is normally what we use.
Re the high pass:
change the Zobel R5 from 30 to 12 and C10 from 2 to 1.5uF.
change the resonance C9 from 8.2 to 4.7uF and the coil L7 , from 2.7 to 1.5 mH.The L7 AWG to start use #18 , add a series small R with the coil (0 TO 5 ohms), use an L pad. We can use a smaller wire gauge in the final design to eliminate the L pad .
With all of this done : Listen to your changes and go with what sounds best.
Don
Thanks again for all your help on this Don.Quote:
Originally Posted by donaldpatten
I played around tonight with the resonance trap and the zobel for the HF driver.
The best zobel I could get was R=10 ohms and C=1.33 uF. This yielded a pretty flat line from 2.6 KHz all the way out to 20 KHz. The resonance trap is a pain to dial in! My calculations showed I need C=6.3 uF, L=1.2 mH, and R=5.2 ohms. This is based on a resonance peak at 1812 Hz (a little different now with the zobel), and the following T/S:Re = 6.479, Qes = 2.16 and Qms =3.95.
My magnet wire should be arriving tomorrow, and I can wind some coils and try to build the HF filter...
https://live.staticflickr.com/65535/...0ea7c105_b.jpg