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-   -   how test electronic crossover without any instruments? (http://www.diyaudio.com/forums/analog-line-level/197082-how-test-electronic-crossover-without-any-instruments.html)

soundnovice 22nd September 2011 05:41 AM

how test electronic crossover without any instruments?
 
hi all,

i have rigged up circuit for 2-way crossover circuits as per Rod Elliott's project 9.
Linkwitz-Riley Electronic Crossover

i dont have signal generator or oscilloscope. i have a pair of full range drivers (old pioneer 4") and T-amp (max 25W/channel). Please let me know how can i test that the crossover circuit is doing its job.

thanks,
Pranam

theAnonymous1 22nd September 2011 05:48 AM

Well, you have a computer right? There is software available that can do what you want (RightMark?). Someone else can chime in on specifics; I'm posting from my phone.

thaumaturge 22nd September 2011 07:25 AM

This will provide you with an audio spectrum analyzer that works with a sound card input. Just have to find a sweeper or pink noise program. Don't know if the gen software also listed is free, if not keep looking.

DL4YHF's Audio Spectrum Analyser
Free Download Audio Multi-Tone Generator 5.0 - Multi-tone audio frequency signal generator

When you get both, you may have to run one on a laptop and one on a desktop. Take a direct gen to analyzer plot as a reference then insert crossover and sample different outputs (Bass, mid, treble). The difference between the reference and the output plots are what the crossover is doing.
(Pink noise is frequency related, White noise is flat across band, use whichever you need).
Doc

thaumaturge 22nd September 2011 08:10 AM

Dang, missed my edit window and now have to type this part twice!


Alternately, the test can be made with only a signal generator (program), a diode, an integrating cap and any DVM. Run signal through diode (input on anode side) and connect integrating cap to cathode side and other leg to ground. DVM reading is across the integrating cap. Take a straight through reading for each frequency step and then record it (write it down). Then take all the same measurements connecting diode to outputs on crossover. (May need to load other legs of crossover with dummy resistors depending on circuit). Diode can be 1N4148 or even a 1N4001. Cap should be a .1uF mylar. Crossover response in db is dB = 20 * Log(Vout / Vin) [where Vin is direct reading and Vout is through crossover reading] If you feed the readings into an excell spreadsheet you can just plug in the formula and it will draw you a graph.
Doc

thaumaturge 23rd September 2011 05:08 PM

Oh, forgot to add a 1Meg bleeder resistor across cap.... do so or charge on cap will just sit there at peak value... save very slow discharge by 10meg DVM load. Doh!
Doc

soundnovice 26th September 2011 04:41 AM

Quote:

Originally Posted by thaumaturge (Post 2721624)
Oh, forgot to add a 1Meg bleeder resistor across cap.... do so or charge on cap will just sit there at peak value... save very slow discharge by 10meg DVM load. Doh!
Doc

thanks thaumaturge, i think its the simples way to test the xover ckt. will try this.

geraldfryjr 27th September 2011 11:11 PM

Winlsd has a Built in signal generator as well.

I have also used Audacity to do such measurements as it will playback a track as you record a new one ,and it also has a built in FFT function to view the frequency response of the selected track.
The chrip function is what you use to create the sweep frequency track.

There are many different free programs to do this,HOLMImpulse is another good one as it will show THD in db as well.

jer :)

Nico Ras 29th September 2011 03:07 PM

Check here www.sillanumsoft.org/Download/VA.exe
Visual analyzer. But remember to protect the input of your sound card against high voltage if feeding it with an amp.


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