You'd have to use Ohm's law, and Kirchoff's laws. You want the same acoustical output from each driver.
But there's no way to know the relative outputs of the two different kinds of drivers to begin with.
They will be different.
By symmetry, the voltage at the junction of the middle two 2.4R will be halfway between the two ends.
But there's no way to know the relative outputs of the two different kinds of drivers to begin with.
They will be different.
By symmetry, the voltage at the junction of the middle two 2.4R will be halfway between the two ends.
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re:"Use your multimeter" - that's too practical.... actually it would be too time consuming to wire that actual drivers ATM, so I wired up some 2.7 ohm & 10 Ohms resistors, got 6.1 ohms, so I'm on the right track. re:'What imedance you want?' - anything over 3 ohms would be OK
Re:'I would do it differently' - I don't think that method would share the power enough
Re: 'Ohm's law, and Kirchoff's laws' - my googling tells me to use 'Y-delta' analysis, whatever that is.....
Partying to be done, when I get back I'll put 1.5 V across the resistors and find how the voltage is shared
Re:'I would do it differently' - I don't think that method would share the power enough
Re: 'Ohm's law, and Kirchoff's laws' - my googling tells me to use 'Y-delta' analysis, whatever that is.....
Partying to be done, when I get back I'll put 1.5 V across the resistors and find how the voltage is shared
Other than the original question which is a basic engineering problem that can be solved with Ohms and Kirchoffs laws, I think you need to take a step back and ask what are you trying to accomplish by running two types of drivers without a crossover? Speaker drivers aren't just a resistance, but a nominal impedance. An "8ohm" driver may vary from 6ohms up to 40ohms depending on frequency. When you wire two different drivers in series, the frequency response of both is altered. The only exception might be when a manufacturer sells the same driver with different nominal impedances and even then they might be very very similar but not an exact scaling of impedance.
*short answer: draw the circuit in SPICE, apply a DC voltage and see what current flows. Ohms law = answer.
*short answer: draw the circuit in SPICE, apply a DC voltage and see what current flows. Ohms law = answer.
"a basic engineering problem" - I don't think so, look at the schematic again... I know all the other stuff, just assume it needs to be done
Allen, I don't think that's going to share the power well enough
Allen, I don't think that's going to share the power well enough
Say the amp supplies 10V.
Two 10ohms in series is 20ohms, so that's 5V each and half an Amp.
2.5W per 10ohm driver.
Four 2.5ohms in series is 10ohms, so 2.5V each and 1 Amp.
2.5W per 2.5ohm driver.
Total impedance 6.7ohms.
Two 10ohms in series is 20ohms, so that's 5V each and half an Amp.
2.5W per 10ohm driver.
Four 2.5ohms in series is 10ohms, so 2.5V each and 1 Amp.
2.5W per 2.5ohm driver.
Total impedance 6.7ohms.
I think the solution is here, (Example 2.12):
https://www.brainkart.com/article/Resistors-in-series-and-parallel_38413/
https://www.brainkart.com/article/Resistors-in-series-and-parallel_38413/
Your diagram is the wrong way of connecting drivers. You must not connect serially different drivers (even if they have identical Re)! If both drivers (Re=2.4 and Re=10.2) have different resonant frequency Fs (most likely!), then the power distribution changes - drivers impedance peak at Fs will be at different frequencies. The important point to remember is - loudspeaker drivers are not resistors and must not be treated as such!
Important information are missing from your post - what is the sensitivity (SPL at 2.83V/1m) and the maximum power capacity of the drivers? Surely they are different, so even power distribution will result in different SPL from both drivers - which is not what you want, I suppose.
Sonce, there are two problems here - the power distribution problem, elegantly solved by Allen,
and the solution to the resistor problem posed by my schematic above, which no one so far has been able to shed light on
and the solution to the resistor problem posed by my schematic above, which no one so far has been able to shed light on
Did you want to see this:
I put a 5 watt load on it to be able to show both resistor types...
Or what Allen suggested:
Same load...
Just download Xsim and go wild yourself! You can even play with actual impedance traces of real drivers,
as that would totally change the results compared to resistors...
I put a 5 watt load on it to be able to show both resistor types...
Or what Allen suggested:
Same load...
Just download Xsim and go wild yourself! You can even play with actual impedance traces of real drivers,
as that would totally change the results compared to resistors...
Your schematic from post#1 is wrong because you are overlooking the much bigger problem - please read carefully my previous post (#11). You can not represent loudspeaker impedance as a simple resistor and you must not connect serially two different drivers (as in your schematic)!
Simple resistor analogy will work only if you don't mix different drivers in series conection - as in solution by AllenB (contrary to your schematic from post #1)! But, equal power absorption by both 2.4-ohm and 10.2-ohm drivers makes (some) sense only if both drivers have the same maximum power rating - which I highly doubt! Anyway, more logical requirement is both driver legs to have the same SPL output, which may require different power supplied to 2.4-ohm and 10.2-ohm drivers.
Take a look at this solution:
Both 10-ohm driver in parallel make total 5 ohm impedance. With 10 V supplied by amplifier, each 10-ohm driver will receive 10 W (both drivers receive the same wattage).
All four 2.5-ohm drivers in series make total 10 ohm impedance. With 10 V supplied by amplifier, each 10-ohm driver will receive 2.5 W (all four drivers receive the same wattage).
Total impedance of parallel connection of both combination of two different drivers is 3.33 ohms (3.29 total with the exact 2.4-om and 10.2-ohm values of drivers), which is equivalent of a nominally 4-ohm driver.
Advantage of this solution is higher SPL than solution given by AllenB.
I will repeat my questions, please answer them:
What is the sensitivity (SPL at 2.83V/1m) and the maximum power capacity of 2.4-ohm and 10.2-ohm drivers, respectively?
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Sonce, Re:sensitivity (SPL at 2.83V/1m) and the maximum power capacity" - unknown and irrelevant - I'm not concerned with the sensible thing to do,
Thanks Wesayo, though it's not clear to me what your graphs are showing, are the Watt levels for each resistor cumulative?
Thanks Wesayo, though it's not clear to me what your graphs are showing, are the Watt levels for each resistor cumulative?
???
Irrelevant?
Then, what are you trying to achieve? Why are you using different drivers together? Why you must use all 6 drivers together? For what purpose?
Thanks Wesayo.
Here's a method to solve the resistor problem: https://instrumentationtools.com/topic/delta-to-wye-and-wye-to-delta-conversions/
Sonce, re:'what are you trying to achieve' - I have a small sound bar with 4x 2.4 ohm drivers which I'm converting to a mono centre channel. The 10.2 ohm drivers are extras I want to add, the only ones I have that will fit. This is just to use up the drivers, precision & accuracy are not a concern, I just want to hear what the result is. The drivers are all 50mm and have the same sized magnets, probably 5W. An additional constraint is that the two halves of the sound bar click together, but... the connector only has two pins. If it sounds bad, I'm happy to throw it in the bin, at least I've amused myself for a bit.
Here's a method to solve the resistor problem: https://instrumentationtools.com/topic/delta-to-wye-and-wye-to-delta-conversions/
Sonce, re:'what are you trying to achieve' - I have a small sound bar with 4x 2.4 ohm drivers which I'm converting to a mono centre channel. The 10.2 ohm drivers are extras I want to add, the only ones I have that will fit. This is just to use up the drivers, precision & accuracy are not a concern, I just want to hear what the result is. The drivers are all 50mm and have the same sized magnets, probably 5W. An additional constraint is that the two halves of the sound bar click together, but... the connector only has two pins. If it sounds bad, I'm happy to throw it in the bin, at least I've amused myself for a bit.
So, all drivers have about the same maximal power capacity, after all!
OK. First, determine with simple tests which driver is better sounding - 2.4-ohm or 10.2-ohm, although you are repeating that the sound quality is not important to you (you can thank me later). Wire two 2.4-ohm drivers serially and hear some music track. Then, hear the same music track with two 10.2-ohm drivers in parallel connection (in anbother box!). Of course, drivers must be mounted in a closed boxes, without other oppening (however small they are).
Compare which driver is better sounding (not which one is louder!) - if necesarry turn Volume control to get the same SPL.
1. If 10.2-ohm drivers are better, then connect them in parallel (5.1-ohm total impedance) and enjoy. You will get +6dB more SPL sensitivity compared to serial connection of both drivers. Do not use 2.4-ohm drivers!
2. If 2.4-ohm drivers are better, then connect all four in series (9.6-ohm total impedance) and enjoy. Do not use 10.2-ohm drivers!
Or, connect two in series parallel with other two in series (for total of 2.4 ohm, about equivalent of nominal 3-ohm driver, but you will get +6dB more SPL sensitivity compared to the simple serial connection of all 4) and enjoy. Do not use 10.2-ohm drivers!
3. If both drivers have the same sound quality, than use all 6 drivers (if you must use all 6) with the connection AllenB proposed.
OK. First, determine with simple tests which driver is better sounding - 2.4-ohm or 10.2-ohm, although you are repeating that the sound quality is not important to you (you can thank me later). Wire two 2.4-ohm drivers serially and hear some music track. Then, hear the same music track with two 10.2-ohm drivers in parallel connection (in anbother box!). Of course, drivers must be mounted in a closed boxes, without other oppening (however small they are).
Compare which driver is better sounding (not which one is louder!) - if necesarry turn Volume control to get the same SPL.
1. If 10.2-ohm drivers are better, then connect them in parallel (5.1-ohm total impedance) and enjoy. You will get +6dB more SPL sensitivity compared to serial connection of both drivers. Do not use 2.4-ohm drivers!
2. If 2.4-ohm drivers are better, then connect all four in series (9.6-ohm total impedance) and enjoy. Do not use 10.2-ohm drivers!
Or, connect two in series parallel with other two in series (for total of 2.4 ohm, about equivalent of nominal 3-ohm driver, but you will get +6dB more SPL sensitivity compared to the simple serial connection of all 4) and enjoy. Do not use 10.2-ohm drivers!
3. If both drivers have the same sound quality, than use all 6 drivers (if you must use all 6) with the connection AllenB proposed.
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