AudioCircle

Audio/Video Gear and Systems => The Lab => Topic started by: Jmitchell3 on 1 Dec 2019, 05:37 pm

Title: Crossover design from existing PCB crossover?
Post by: Jmitchell3 on 1 Dec 2019, 05:37 pm
Have a set of klipsch floorstanders and wanted to see if I could interpret the crossover design from lookin g at the pcb crossover? I’m not an electrical engineer so was wondering if this is possible?
Title: Re: Crossover design from existing PCB crossover?
Post by: mboxler on 1 Dec 2019, 05:52 pm
What model?  There may already be a schematic available.
Title: Re: Crossover design from existing PCB crossover?
Post by: Jmitchell3 on 1 Dec 2019, 06:16 pm
Quote from: mboxler on  1 Dec 2019, 05:52 pm
What model?  There may already be a schematic available.

Rp-250F
Title: Re: Crossover design from existing PCB crossover?
Post by: Jmitchell3 on 1 Dec 2019, 06:44 pm
Found this on klipsch forums, maybe actual 250F is similar with different part values?

(https://www.audiocircle.com/image.php?id=201552)

(https://www.audiocircle.com/image.php?id=201551)
Title: Re: Crossover design from existing PCB crossover?
Post by: mboxler on 1 Dec 2019, 06:50 pm
Was going to post that schematic, but you beat me to it.

Can you see the values on the capacitors and inductor?  Looks like it is very similar.
Title: Re: Crossover design from existing PCB crossover?
Post by: Jmitchell3 on 1 Dec 2019, 07:00 pm
Quote from: mboxler on  1 Dec 2019, 06:50 pm
Was going to post that schematic, but you beat me to it.

Can you see the values on the capacitors and inductor?  Looks like it is very similar.

From the photo, top to bottom, left to right:

C1 5.1uF
C2 13uF
L1 0.3mH
L2 .51mH
R2 4ohm
R1 5ohm
L3 ???
C3 36uF
Title: Re: Crossover design from existing PCB crossover?
Post by: mboxler on 1 Dec 2019, 08:06 pm
You're almost there!

If you can bee the back of the board, you may be able to see how the components are connected.

If you have an LCR meter, you could measure L3, but you will need to disconnect the crossover from the woofers to get an accurate measurement.
Title: Re: Crossover design from existing PCB crossover?
Post by: HAL on 2 Dec 2019, 01:25 am
Are you just trying to upgrade the existing passive crossover design, or see if it can be improved?   :scratch:
Title: Re: Crossover design from existing PCB crossover?
Post by: Jmitchell3 on 2 Dec 2019, 02:56 am
Quote from: HAL on  2 Dec 2019, 01:25 am
Are you just trying to upgrade the existing passive crossover design, or see if it can be improved?   :scratch:

Ultimately I’d like to improve it if possible, but I’d like to understand the existing design as a starting point.
Title: Re: Crossover design from existing PCB crossover?
Post by: HAL on 2 Dec 2019, 03:45 am
The woofers have a 2 pole low pass filter driving them.  The frequency response of the network will depend on the woofer impedance.

The tweeter has a 3 pole high pass filter driving it.  The parallel L-R is a shelving filter that works with the series resistor to raise the output above its design frequency.  The response will again depend on the tweeter impedance load.

You cannot fully analyze the circuit response without the frequency and phase responses of the woofers and tweeters.

Title: Re: Crossover design from existing PCB crossover?
Post by: Mike B. on 2 Dec 2019, 04:50 pm
Danny at GR Research here at the Audiocircles could greatly improve what you have. If that is something you are interested in doing send him a PM.
Title: Re: Crossover design from existing PCB crossover?
Post by: Jmitchell3 on 4 Dec 2019, 10:12 pm
Quote from: Mike B. on  2 Dec 2019, 04:50 pm
Danny at GR Research here at the Audiocircles could greatly improve what you have. If that is something you are interested in doing send him a PM.

Yeah, its actually his Tech Tuesday on the RP600m that got me thinking about these towers i had sitting in my front office room :)

I've attempted to do my first gated measurements in the center of my living room on a carpeted area using the umik1 faq on speaker measurements. I don't have the equipment to do impedance sweeps, but I did get woofer and tweeter and total spl measurements and decay graphs...

(https://www.audiocircle.com/image.php?id=201648)

(https://www.audiocircle.com/image.php?id=201649)

(https://www.audiocircle.com/image.php?id=201650)


UMIK how to w/ USB calibrated mic https://www.minidsp.com/applications/acoustic-measurements/loudspeaker-measurements (https://www.minidsp.com/applications/acoustic-measurements/loudspeaker-measurements)
Floor Reflection Calculator https://mehlau.net/audio/floorbounce/ (https://mehlau.net/audio/floorbounce/)