You'll only confuse them.
David
Like I said earlier, I think the whole concept of damping factor is not very useful. However, if the source resistance of an amplifier relative to the impedance of a first driver is significant, then connecting a second driver identical to the first driver in-series with the first one, makes the amplifier less of a current source. What is so difficult to comprehend about that?
-Pete
I am looking at different ones but I like M8a and M6a together... qts is around 45
Overview of M8a Drivers_HiVi,Inc
Overview of M6a Drivers_HiVi,Inc
more a thought experiment then anything else
I am a little confused about the amount of bass you can get from an open design.
I know you need a low fs and a good baffle for wave blockage but can you get it to where it punches like a passive cab which I am used to?
Overview of M8a Drivers_HiVi,Inc
Overview of M6a Drivers_HiVi,Inc
more a thought experiment then anything else
I am a little confused about the amount of bass you can get from an open design.
I know you need a low fs and a good baffle for wave blockage but can you get it to where it punches like a passive cab which I am used to?
I can hijack my own thread? Since so many gurus are on this thread... can you wire a 8 inch to a 6 inch with no crossover and let them work together the idea is that the six inch will naturally emphasize the higher and the 8 the lower.... the drivers from the same family? Don't beat me up... this is how we learn. I am thinking of an open baffle.
You mean hijack it back since we already hijacked it away.
No problem with an 8 and a 6 in parallel except you can't be sure what will happen at high frequencies. At mid frequencies they will have similar phase response and should always add. At higher frequencies where they will each do their own thing, then their response curves are likely to deviate and they may have some frequencies of cancelation rather than addition. (They might deviate at LF too, but only if their resonances are far apart.)
Try it and see how smooth the response is on pink noise. They might stay in phase best on an axis other than straight out. Your best bet, after you build it up, is to experiment with an inductor on the 8", try different values and work your way into a simple crossover.
Now where were we?
David S.
A lot of people get hung up with two woofers in series. If an 8 ohm resistor in series with and 8 ohm woofer dramatically drops damping, yet an 8 ohm woofer in series with a second woofer doesn't change damping (they voltage split exactly), the nuance that damping actually goes up (since it is now a 16 ohm woofer driven by the same amplifier source resistance) isn't always logical.
Or maybe it is.
David S.
Hi,
Unless the baffle is massive the short answer is no. Baffle loss not only
modifies the frequency response it throws away driver excursion as well.
A typical 15" 96dB, 35Hz Fs, ~ 1 Qts driver in a 2ft wide tall baffle
will go about as loud as a typical 8" 88dB driver in a box. If you
can accept this for the bass quality given fine, but OB is not
IMO for those who want to really crank it, unless you chuck
money at it to get the SPL you want, that is expensive.
rgds, sreten.
Thanks for the explanation. Yes, I would say that I don't exactly understand the difference that you describe.
What about this layout, what ohm's will be seen by the amp if all the drivers if all the drivers are 4 ohm's?
http://www.diyaudio.com/forums/multi-way/200040-stereophonic-sound-single-loudspeaker-2.html
(Further questions coming! I would like to use this with two drivers on the mono section.)
-Tom-
http://www.diyaudio.com/forums/multi-way/200040-stereophonic-sound-single-loudspeaker-2.html
(Further questions coming! I would like to use this with two drivers on the mono section.)
-Tom-
You can wire a 6" and 8" in series. But the results will depend on their impedance curves. Let me exaggerate to a 12" and 3": If the 12" impedance rises faster & higher compared to the 3" (quite likely), at high frequencies the voltage will mostly drop across the 12"! So you won't get that much treble out of the 3" after all.
By the way folks, there is NO such thing as "identical" drivers. The impedances are always somewhat different. This means what was said above about the Q is not really true. In actuality, let's say you have two "identical" woofers in separate "identical" sealed cabinets. One might have its resonance at 33 Hz, and the other at 36 Hz. The first will get much more voltage at 33 Hz, the second at 36 Hz. The voltages won't divide smoothly at all and you can't just extend the damping analysis on that basis.
Then at high frequencies, the impedance curves are not identical. THEN, if in common cavities, at excursion extremes the drivers will each behave differently and exhibit different instantaneous impedances, and the voltage will divide even more unevenly.
So THAT's why series designs aren't generally favored.
By the way folks, there is NO such thing as "identical" drivers. The impedances are always somewhat different. This means what was said above about the Q is not really true. In actuality, let's say you have two "identical" woofers in separate "identical" sealed cabinets. One might have its resonance at 33 Hz, and the other at 36 Hz. The first will get much more voltage at 33 Hz, the second at 36 Hz. The voltages won't divide smoothly at all and you can't just extend the damping analysis on that basis.
Then at high frequencies, the impedance curves are not identical. THEN, if in common cavities, at excursion extremes the drivers will each behave differently and exhibit different instantaneous impedances, and the voltage will divide even more unevenly.
So THAT's why series designs aren't generally favored.
Um.
Perhaps I mixed two differents parts of the hijacked thread.
I was referring to a series connection. A big woofer will typically have very high impedance at high frequencies (let us pretend 90 ohms at 20 kHz). A small speaker like a 3" will have a not so high impedance (let us pretend 10 ohms at 20 kHz). With a simple series connection, the woofer will take 90% of the voltage and the 3" only 10% of the voltage, -20 dB down.
(I'm ignoring the phase angle of the impedance).
That is why series crossovers have bypass elements, i.e. something to short-circuit the big woofer at high frequencies.
In parallel, both drivers see the full voltage, so the crossover elements try to block the frequencies that each driver is not good for.
I *hope* that un-confuses things????
I think the confusion, which maybe I worsened in another post, is a confusion between the WOOFER's own damping (Qts) and the "damping factor" of the amplifier.
The woofer's own damping is set by the mass, suspension, and magnetic system.
- Connecting woofers in parallel does not change Qts
- Connecting woofers in series would not change Qts IF IF IF the woofers were 100% identical in impedance curves at all drive levels. This never happens, so in real life you'll get a complicated mess.
The "damping factor" of the amplifier is really the output impedance versus the impedance of the woofer(s) PLUS the connecting cable. So changing woofers from series to parallel will change the "damping factor" of the amp vs. the woofers.
This probably doesn't matter except for poor solid state amps and for tube amps. But those cases don't matter. Once the output impedance of the amp is so high that series vs. parallel connection makes a difference, the amp is not really a voltage source any more. The amp is no longer accurate as a pure amplifier, and we are into the realm of "it measures like dog poop from an engineering point of view, but sounds very nice in some cases." The sound in those cases depends heavily on the complex dynamic output impedance of the amp vs. the complex dynamic impedance of the speaker...plus the cable(s) in between! This is the realm of synergy, not science.
Even in the case of 33 and 36Hz resonances you won't find the impedance curves that dramatically different. You may get a bit of complimentary "s" shaped errors between the two units but I don't think it would be disqualifying. Interestingly, the combined response of the two would be much like the series combination of a pair of 34.5Hz woofers, and the "damping" effect would be the same in the end.
People series parallel units all the time and have no difficulties if the units are a reasonable match.
David S.
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