Hi guys,
I am upgrading my cabinets - Schneider LS-8036 (double woofer + midrange+ tweeter). And now its time for making crossovers. The problem that woofers are 4 ohms each, and my amp NAD 3020 not suppose to handle something bellow 4 ohms load.
I decided to go with series connection (2 woofers + midrange and tweeter) thus load that amp will see be around 6 ohms. But not much examples i saw on designing crossovers for series speaker connections. I made a scheme (see it attached), and would like your advises on few points:
- If i attach on first speaker the coil L1, that means that coil will apply to the second speaker in series too? or I need to add another one on the line from one speaker output to anohter's input?
- And about capacitors on C2 midrange and C1 tweeter, if i add on tweeter 3,3uF (C1) and i need that midrange will receive 10uF, so i need just to add 6,6uF (C2) on the line from output of tweeter to input of midrange?
- will in this connection woofers still receive 3 more decibels as they are combined together, than if only one would be connected?
And please add some tips to newbie in crossover design 🙂 The sound quality is most important here
I am upgrading my cabinets - Schneider LS-8036 (double woofer + midrange+ tweeter). And now its time for making crossovers. The problem that woofers are 4 ohms each, and my amp NAD 3020 not suppose to handle something bellow 4 ohms load.
I decided to go with series connection (2 woofers + midrange and tweeter) thus load that amp will see be around 6 ohms. But not much examples i saw on designing crossovers for series speaker connections. I made a scheme (see it attached), and would like your advises on few points:
- If i attach on first speaker the coil L1, that means that coil will apply to the second speaker in series too? or I need to add another one on the line from one speaker output to anohter's input?
- And about capacitors on C2 midrange and C1 tweeter, if i add on tweeter 3,3uF (C1) and i need that midrange will receive 10uF, so i need just to add 6,6uF (C2) on the line from output of tweeter to input of midrange?
- will in this connection woofers still receive 3 more decibels as they are combined together, than if only one would be connected?
And please add some tips to newbie in crossover design 🙂 The sound quality is most important here
Attachments
Read, learn & inwardly absorb: Introduction to designing crossovers without measurement and Simulated Measurements - undefinition.
Now, on to your proposal.
As you have three passbands (bass, mid and tweeter) its a 3 way crossover, not a 4 way.
Yes, you can put the 2 woofers in series for a nominal 8Ω impedance in that passband.
Yes, using one inductor to feed both woofers will work fine - it will end up being a different value than if you used only one woofer, because the impedance is different, but your modelling (XSim by the looks of it) will give you the chance to work that out for yourself.
Yes, technically you can put the mid and tweeter in series, but that changes how you lay out the respective components for their individual filters - it's more complicated than traditional parallel crossovers and I haven't learnt anything about it yet, so can't help you there I'm afraid.
However - you don't have to use a series crossover for your mid and tweeter.
Remember that the filter components effectively prevent the amp "seeing" the impedance of each driver outside its own band of frequencies, so a traditional parallel layout between your 8Ω combined bass, then your individual mid & tweeter will still give an overall impedance your amp can handle. It would look like this drawn out - note that using the ground symbol to connect up all the "-ve" parts of the circuit leaves a clearer diagram.
Hope this helps,
David.
Attachments
Hi David,
thanks a lot for the response that clarified the issue i am tackling.
Yes those were useful readings, but not much on 3way and impedance handling.
But actually your post explains how to handle the load to amp rather well. Does it mean that amp sees impedance only the one that was produced by the speakers at that range. Thus if tweeter is not playing at a hearable volume on low frequencies it doesn't cause any additionally load to that frequency point to amp, and opposite for woofers?
I actually have another question. If you have 1 8ohm woofer will the output be same volume (db per 1watt) as produced by 2 same name woofers, only 4ohm, connected in series, or 2 woofers in series will bring in theory 3db more?
thanks a lot for the response that clarified the issue i am tackling.
Yes those were useful readings, but not much on 3way and impedance handling.
But actually your post explains how to handle the load to amp rather well. Does it mean that amp sees impedance only the one that was produced by the speakers at that range. Thus if tweeter is not playing at a hearable volume on low frequencies it doesn't cause any additionally load to that frequency point to amp, and opposite for woofers?
I actually have another question. If you have 1 8ohm woofer will the output be same volume (db per 1watt) as produced by 2 same name woofers, only 4ohm, connected in series, or 2 woofers in series will bring in theory 3db more?
Yes, that is it exactly.
So, you want to compare one 8Ω woofer with (for example) 88dB sensitivity for the standard 2.83V input, with two 4Ω woofers, each having the same 88dB/2.83V sensitivity, wired in series to get an equivalent 8Ω load.
If we then apply the same 2.83V signal to each part of the comparison, the single 8Ω woofer produces its expected 88dB, no problem.
The pair of 4Ω woofers will produce 88dB as well. This is because of them being in series - therefore each of them only "sees" half of the applied voltage, so each one will produce less volume, but their outputs combine as if they together were a more efficient driver.
They will be capable of getting 3dB louder, at maximum power, because between them they can handle twice as much power.
Note that most speakers are not perfect 8Ω or 4Ω loads, and they do not have the same impedance at all frequencies, so instead of trying to apply 1Watt, which would be a constantly moving target, speaker manufacturers apply 2.83V when doing their tests, (being the equivalent of 1W into a theoretically perfect 8Ω load). So it’s best to try and think in terms of voltage rather than wattage for comparisons like this.
Cheers,
David.
Do a search. Diaural crossover, by Ray Kimber. This is a great starting point.
Your C1, 3.3uF will also block frequencies to the midrange. There needs to be an alternative path.
Your C1, 3.3uF will also block frequencies to the midrange. There needs to be an alternative path.
Here is a link to his patent. Click on the pictures. Try to get a feel for the way it separates frequencies.
US6381334B1 - Series-configured crossover network for electro-acoustic loudspeakers
- Google Patents
US6381334B1 - Series-configured crossover network for electro-acoustic loudspeakers
- Google Patents
Thanks David, i am learning a lot from you.
Well, then in theory not much of advantages to put double 4 ohm woofers if you could put one with 8 ohms.
Well, then in theory not much of advantages to put double 4 ohm woofers if you could put one with 8 ohms.
Crossovers without capacitors, wow that's something to experiment. I just wonder on what basis they put 8ohm resistor between tweeter negative and amp ground? Is it just the value of tweeter impedance?
Please disregard this sub-optimal version of a serial crossover. It is a waste of amplifier power combined with non-ecological production of heath.
Not quite so.
Class A amps generate more heat because of lower efficiency, but they have no crossover distortion, so maybe there is some benefit in sound quality.
Diaural crossover have no audio benefit over regular series crossover and they draw more power from class AB or D amps, generating more heat from amps and more heat from the resistors in the crossover.
Class A amps generate more heat because of lower efficiency, but they have no crossover distortion, so maybe there is some benefit in sound quality.
Diaural crossover have no audio benefit over regular series crossover and they draw more power from class AB or D amps, generating more heat from amps and more heat from the resistors in the crossover.
strong point
but the benefits aspect for amateur diyer point of view its easy to test. In one cabinet Diaural is implemented, in another ordinary crossovers, and you keeping the ones with "preferred" differences, if no hearable differences - leaving simpler version 🙄
No, it is not easy to test. Which crossover is simpler is a dubious question. Diaural crossover demands high power resistor, series crossover need a small capacitor. Which one is simpler?
Also, tweeter in Diaural crossover must be with higher efficiency, because it is attenuated by the resistor which is inherent in the design. On the other hand, tweeter in the series crossover may be with the same (low) efficiency as the midbass driver.
Also, tweeter in Diaural crossover must be with higher efficiency, because it is attenuated by the resistor which is inherent in the design. On the other hand, tweeter in the series crossover may be with the same (low) efficiency as the midbass driver.
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