Zobel placement?
- Thread starter Justgotohm
- Start date
Justgotohm
Super Member
Just one sub per cabinet, each cabinet on opposite sides of the room in stereo. The crossovers are 2nd order 12mh coil and 375uf of caps. I decided to use the Zobel only based on what I've read in it keeping the ohms stable ? This is my first crossover and built them based on calculators online. If I had more invested I feel I would have used better components and maybe not built it so generic. I matched the cap and resistor to the parameters Parts Express listed for the woofers using another online calculator. I read conflicting answers on weather the Zobel should be mounted on the board or on the woofer itself. I included a pic above. Thanks
BinaryMike
Pelagic EE
Zobel networks in xovrs are usually there to maintain a constant load impedance on the filter network so it behaves as predicted by the design equations. Because Zobel design is governed by driver characteristics, one could assert that it belongs at the driver. What happens if you decide to use that driver with some other xovr? Suppose you put the Zobel at the xovr -- then what happens if you connect it to a different driver? I suggest there is no correct answer to this question.
Justgotohm
Super Member
Ok, sorry I just got a minute to draw this up. I included all caps used not just the values needed. I hooked the Xover up to the woofers on my bench and everything seemed to do what it should as far as sound outside of the cabinets. I am grateful to anyone who can give me a point in the right direction as to the effectiveness of this network. As stated this is a first so I went pretty cheap and given these are subs. Thanks you guys for the input.
Justgotohm
Super Member
I assumed the Zobel is specific to the speaker it is designed for given it is the speakers parameters that are used?
The best article that I've read concerning a Zobel circuit is at Rod Eliot's Eliot Sound Products site.
http://sound.westhost.com/lr-passive.htm#s3.1
You are correct that the Zobel is specific to the driver it's being used on.
My Speakerlabs came with a Zobel for the woofers built into the crossover. When I rebuilt the speakers I bought Smith & Larson's Woofer Tester 2 software/hardware to test the new drivers. It has the ability to calculate for a Zobel also. (no affiliation)
http://www.ht-audio.com/pages/WooferTester2.html
I had the complication that there are 2 woofers per box, 1x 12" and 1x 10". I still had the original 12" and a new Scan-Speak 10". I found that there was a small change needed in the circuit for the capacitor, the resistor stayed the same.
When I first added a Zobel to my mids I put it directly on the drivers. Later when I completely replaced the crossover I put both Zobels (woofers & mids) in the crossover. There was no hearable difference.
In your schematic above it shows a 43ohm resistor in the Zobel. That seems very high. Are you sure that it's not supposed to be 4.3ohms? Everything that I've seen/read so far shows that the resistor in the Zobel will be at or near the nominal impedance of the driver. For instance my 4ohm mids (3.2 ohm DCR) calculated out to need a 3.9ohm resistor and a 22µF cap. You might want to recheck that.
Cheers,
James
http://sound.westhost.com/lr-passive.htm#s3.1
You are correct that the Zobel is specific to the driver it's being used on.
My Speakerlabs came with a Zobel for the woofers built into the crossover. When I rebuilt the speakers I bought Smith & Larson's Woofer Tester 2 software/hardware to test the new drivers. It has the ability to calculate for a Zobel also. (no affiliation)
http://www.ht-audio.com/pages/WooferTester2.html
I had the complication that there are 2 woofers per box, 1x 12" and 1x 10". I still had the original 12" and a new Scan-Speak 10". I found that there was a small change needed in the circuit for the capacitor, the resistor stayed the same.
When I first added a Zobel to my mids I put it directly on the drivers. Later when I completely replaced the crossover I put both Zobels (woofers & mids) in the crossover. There was no hearable difference.
In your schematic above it shows a 43ohm resistor in the Zobel. That seems very high. Are you sure that it's not supposed to be 4.3ohms? Everything that I've seen/read so far shows that the resistor in the Zobel will be at or near the nominal impedance of the driver. For instance my 4ohm mids (3.2 ohm DCR) calculated out to need a 3.9ohm resistor and a 22µF cap. You might want to recheck that.
Cheers,
James
Justgotohm
Super Member
i just checked my order from PE and I had ordered 4.3ohm resistors as far as the schematic goes I did not make the point in 4.3 very legible which is not a good thing if you trying to explain something. Thank you very much for pointing that out and sending the link.
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Cheers,
James
67dylan
Active Member
Lol, I thought that was 43ohms...that would have been a problem. I usually keep the crossover our of the speaker until I like the sound. It's much easier to tweak.
I'd keep everything on the board, but that is by choice. Easier for me to work on the board instead of the speaker.
I'd keep everything on the board, but that is by choice. Easier for me to work on the board instead of the speaker.
