I notice that the nominal impedance of the centre speaker is 6 ohm.
That begs the question, what is the nominal impedance of a single mid-woofer?
The impedance is important in relation to the final crossover used to marry the single mid-woofer with the tweeter.
I would definitely not bet my life on that ! 😉
https://www.audioheritage.org/vbulletin/showthread.php?7564-Imaginary-Equivalent-Tuning
Regards
Charles
😱
if the Beta multimeter (on loan) is correct, the value is about/almost 8ohm impedance - the model is 1334.
the crossover is very simple, but given how the box was built, a single volume with the reflex in the center, I'm also amazed how it can sound like this. evidently these mid-woofers, heavy in kevlar are well made.
the inside of the box is not what i thought - it has only one layer of absorbent material on/opposite side of the woofer. it can be improved!!!
if the Beta multimeter (on loan) is correct, the value is about/almost 8ohm impedance - the model is 1334.
the crossover is very simple, but given how the box was built, a single volume with the reflex in the center, I'm also amazed how it can sound like this. evidently these mid-woofers, heavy in kevlar are well made.
the inside of the box is not what i thought - it has only one layer of absorbent material on/opposite side of the woofer. it can be improved!!!
According to an old ebay listing, a 1334 woofer from a Diamond 8 centre speaker has an impedance of 16 ohm.
Were you measuring across the input terminals of the centre speaker system to get your ~8 ohm reading or across the terminals of a single woofer?
Were you measuring across the input terminals of the centre speaker system to get your ~8 ohm reading or across the terminals of a single woofer?
Hi Galu, I dismantled the entire central speaker and measured the single woofer at its terminals with the tester, but don't take my measurement as valid. Now I'll repeat it with the tester and take a photo.
Tweeter 0326h,
at this point, the question I ask myself is the following: the nominal impedance of 6Ohm, how did they calculate it?
I made a two-way 24dB/octave simulation.
at this point, the question I ask myself is the following: the nominal impedance of 6Ohm, how did they calculate it?
I made a two-way 24dB/octave simulation.
The "nominal" impedance of the Diamond 8 centre speaker is 6 ohm.
The word "nominal" tells us the impedance does not necessarily correspond to exactly 6 ohm.
Two 16 ohm woofers connected in parallel inside the centre speaker will result in a combined load of 8 ohm.
Wharfedale state that all the speakers in the Diamond 8 series are 6 ohm nominal, this simply being an amplifier matching guide.
I can find no specs for the Wharfedale 0326H tweeter, but it is likely to have a nominal impedance of 6 ohm.
In my opinion, your crossover network is unnecessarily complicated.
If using a crossover calculator, I suggest you go for a 2nd order (12 dB/octave) calculator like the one in the link below, and enter 16 ohm for the woofer and 8 ohm for the tweeter.
https://soundcertified.com/speaker-crossover-calculator/#:~:text=You can also use a general rule based,and divide by 8 to get the 2nd.
A crossover frequency of 3.5 kHz would probably be about right.
Last edited:
wow!
the impedance of their calculations should then be: 8+8+8 / 3 = 5.333 ?
nice calculation at 3500 in second order 12db
I know I'll do eight million tests with capacitors, inductors and resistors like there's no tomorrow, I can already imagine the all-flying prototype crossover. 🙂
the impedance of their calculations should then be: 8+8+8 / 3 = 5.333 ?
nice calculation at 3500 in second order 12db
I know I'll do eight million tests with capacitors, inductors and resistors like there's no tomorrow, I can already imagine the all-flying prototype crossover. 🙂
The tweeter is not in parallel with the woofers. At no frequency do they play freely together.
Look at any typical speaker impedance and it varies with frequency.. so it's difficult to call it anything. It's kind of an average even though it's not.
6 ohms nominal is like a warning not to use two of them in parallel on a 4 ohm amplifier 😉
What you are probably looking for is a number you can use in the calculator you posted about in #27? You would be better to look at the impedance plot for the driver and pick what it is near the cross. While you're there, look at the response falling off and you'll see that 12dB/oct there adds to your 24dB/oct filter to make 36dB/oct.
6 ohms nominal is like a warning not to use two of them in parallel on a 4 ohm amplifier 😉
What you are probably looking for is a number you can use in the calculator you posted about in #27? You would be better to look at the impedance plot for the driver and pick what it is near the cross. While you're there, look at the response falling off and you'll see that 12dB/oct there adds to your 24dB/oct filter to make 36dB/oct.
Unfortunately, Jeff, you will not have access to a woofer impedance plot.
Consequently I suggest that you, initially at least, make do with the numbers I suggested in post #28.
I regard this as a "get it up and running" exercise rather than a strict exercise in crossover design.
Consequently I suggest that you, initially at least, make do with the numbers I suggested in post #28.
I regard this as a "get it up and running" exercise rather than a strict exercise in crossover design.
Yes and with your experience you can see two moves ahead. It might not hurt to throw out a few ideas now and then to see what sticks, especially when you see someone wandering too far from the path 😉
Like AllenB implied, the impedances do not simply add up, nor do we average them.
Besides, we have established that the woofers are each of 16 ohm nominal impedance, not 8 ohm.
P.S. The 13 ohm (allowing for the resistance of the test leads) that you measured with your ohmmeter is the DC resistance of the woofer. To make an estimate of the nominal impedance we would add on one third of that 13 ohm figure.
P.P.S. Resistance is the opposition to DC. Impedance is the opposition to AC, and is higher than the resistance of a driver over the majority of its operating frequency range.
As long as those ideas are adequately explained to the novice recipient, I have no argument with that! 😉
Frankly I'm not going to explain everything in advance, but if they are interested....
By the way, 5.333 is 16 ohms in parallel with 8 ohms which is where I presumed the frequency split explanation was warranted.
By the way, 5.333 is 16 ohms in parallel with 8 ohms which is where I presumed the frequency split explanation was warranted.