audioguru2
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How do you figure the impedance for each side?
Car speakers are usually 4 ohms each. Therefore at high frequencies each side has a 3-way and a tweeter in parallel, resulting in 2 ohms.
Adding the woofer lowers the resulting impedance at low frequencies the same.
The TDA1554 IC is designed to power no less than 4 ohms for each side, so it is overloaded at both low and high frequencies.
You need to add a separate amp to power the tweeters and you should add a 3rd more powerful amp for the woofer. I have never seen a woofer connected to both channels like you have, but I guess it will work allright. This connection does not give you separate control of woofer and tweeter levels but maybe resistors can be added to the tweeters to attenuate them.
The tweeters should have capacitors in series with them to keep low frequencies out of them. The woofer should have an inductor in series with it because woofers play medium frequencies strangely. Try it without an inductor and if you don't like the sound, an inductor can be added later. The inductance of the woofer prevents it from being in parallel with the tweeters so the amp isn't overloaded.
The system will end up looking like this:
View attachment 37920
Car speakers are usually 4 ohms each. Therefore at high frequencies each side has a 3-way and a tweeter in parallel, resulting in 2 ohms.
Adding the woofer lowers the resulting impedance at low frequencies the same.
The TDA1554 IC is designed to power no less than 4 ohms for each side, so it is overloaded at both low and high frequencies.
You need to add a separate amp to power the tweeters and you should add a 3rd more powerful amp for the woofer. I have never seen a woofer connected to both channels like you have, but I guess it will work allright. This connection does not give you separate control of woofer and tweeter levels but maybe resistors can be added to the tweeters to attenuate them.
The tweeters should have capacitors in series with them to keep low frequencies out of them. The woofer should have an inductor in series with it because woofers play medium frequencies strangely. Try it without an inductor and if you don't like the sound, an inductor can be added later. The inductance of the woofer prevents it from being in parallel with the tweeters so the amp isn't overloaded.
The system will end up looking like this:
View attachment 37920
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I meant speakers no. 4,2 and ( "1" is connected to both sides) have 4 ohms totaly. and the same thing for 5,3 and 1 = 4 ohms , I have measured it.
The tweeters have caps in series and the woofer also has an inductor connected in series
The tweeters have caps in series and the woofer also has an inductor connected in series
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Hi
Mukhalled, how did you measured the impedance of the speakers?
Audioguru, dont you think the amp #2 is going to be slant loaded by the subwoofer speaker? There is speakers with 2 voicecoils, specially made for this purpose.
The right way to do it, i belive, is to use one amp for the subwoofer and an active filter and a summing amp before that.
//Staigen
Mukhalled, how did you measured the impedance of the speakers?
Audioguru, dont you think the amp #2 is going to be slant loaded by the subwoofer speaker? There is speakers with 2 voicecoils, specially made for this purpose.
The right way to do it, i belive, is to use one amp for the subwoofer and an active filter and a summing amp before that.
//Staigen
audioguru2
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Hi Mukhalled,
If the 3-way speakers and the tweeters are all 4 ohms each, then each amplifier has a 3-way speaker in parallel with a tweeter and has a 2 ohm load at high frequencies. Therefore the amp is overloaded.
You probably measured the DC resistance, but the capacitor in series with the tweeter prevented you from measuring it.
If your woofer is also 4 ohms then the amps are also overloaded at low frequencies.
Since the woofer is connected between different amps then you can't measure its resistance in parallel with a 3-way speaker.
Your amp is overloaded and will fail!
I use Microsoft Paint to copy, paste and sketch schematics.
Hi Staigen,
I think Mukhalled discovered a cool way to power his woofer in mono. Then he doesn't need to replace it with a dual voice-coil one. The amps for the tweeters won't even notice its odd wiring. If he needs more power for it then he'll need a separate amp for it. ;D
View attachment 37921
If the 3-way speakers and the tweeters are all 4 ohms each, then each amplifier has a 3-way speaker in parallel with a tweeter and has a 2 ohm load at high frequencies. Therefore the amp is overloaded.
You probably measured the DC resistance, but the capacitor in series with the tweeter prevented you from measuring it.
If your woofer is also 4 ohms then the amps are also overloaded at low frequencies.
Since the woofer is connected between different amps then you can't measure its resistance in parallel with a 3-way speaker.
Your amp is overloaded and will fail!
I use Microsoft Paint to copy, paste and sketch schematics.
Hi Staigen,
I think Mukhalled discovered a cool way to power his woofer in mono. Then he doesn't need to replace it with a dual voice-coil one. The amps for the tweeters won't even notice its odd wiring. If he needs more power for it then he'll need a separate amp for it. ;D
View attachment 37921
Hi again,
It was hard to draw schematic circuit so i took the one that Audioguru did before and made some changes on it ;D.
When I measured the impedance like it shows in the attachment, I disconnected the amplifier and it was not 4 ohms but i added some resistors in parallel, then it became 4 ohms 8). This was the right side. I measured the left side and did the same thing to get 4 ohms.
*(There is a filter connected to the bass speaker to get low frecuencies)
It was hard to draw schematic circuit so i took the one that Audioguru did before and made some changes on it ;D.
When I measured the impedance like it shows in the attachment, I disconnected the amplifier and it was not 4 ohms but i added some resistors in parallel, then it became 4 ohms 8). This was the right side. I measured the left side and did the same thing to get 4 ohms.
*(There is a filter connected to the bass speaker to get low frecuencies)
audioguru2
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Hi Mukhalled,
Don't do that!
By adding 4 ohms to the amp now its load impedance is 1.33 ohms.
Hi Staigen,
Mukhalled previously sketched the speaker system that shows each channel with a 2 ohm load at high frequencies, and a 2 ohm load at low frequencies, with the heating brilliantly divided between the amps for low frequencies.
The amps attempted to drive peak currents of at least 5A though the speakers but the absolute max peak current rating of the TDA1554 IC is only (!) 4A.
Amps don't have a massive current capability like the mains where you can keep connecting stuff in parallel with it. Now Mukhalled added even more stuff as a load for his amp.
Don't do that!
By adding 4 ohms to the amp now its load impedance is 1.33 ohms.
Hi Staigen,
Mukhalled previously sketched the speaker system that shows each channel with a 2 ohm load at high frequencies, and a 2 ohm load at low frequencies, with the heating brilliantly divided between the amps for low frequencies.
The amps attempted to drive peak currents of at least 5A though the speakers but the absolute max peak current rating of the TDA1554 IC is only (!) 4A.
Amps don't have a massive current capability like the mains where you can keep connecting stuff in parallel with it. Now Mukhalled added even more stuff as a load for his amp.
Hi Audioguru,
I didn't add 4ohms, it was just the ohmmeter which showed 4ohms.
View attachment 37926
I didn't add 4ohms, it was just the ohmmeter which showed 4ohms.
View attachment 37926
audioguru2
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Hi Mukhalled,
You said you disconnected the amplifier and added resistors in parallel. Then you posted a sketch with "a 4 ohm resistor" added in parallel.
Post a sketch of how it is wired including the resistors you added!
View attachment 37927
You said you disconnected the amplifier and added resistors in parallel. Then you posted a sketch with "a 4 ohm resistor" added in parallel.
Post a sketch of how it is wired including the resistors you added!
View attachment 37927
audioguru2
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Mukhalled,
You can't measure impedance with an ohmeter, just measure resistance. You can't measure the resistance of the tweeters because they have a capacitor in series with them. You can't measure the resistance of a channel including the woofer because the woofer is connected between different amps.
The 3-way speakers also have a cap in series with their mid-range and tweeter parts so you can't measure the resistance of them, just the woofer part of them.
A 4 ohm speaker has a resistance of about 3.5 ohms plus the resistance of your meter's probes.
Please show a sketch of the amp, speakers and the resistors you added. ;D
You can't measure impedance with an ohmeter, just measure resistance. You can't measure the resistance of the tweeters because they have a capacitor in series with them. You can't measure the resistance of a channel including the woofer because the woofer is connected between different amps.
The 3-way speakers also have a cap in series with their mid-range and tweeter parts so you can't measure the resistance of them, just the woofer part of them.
A 4 ohm speaker has a resistance of about 3.5 ohms plus the resistance of your meter's probes.
Please show a sketch of the amp, speakers and the resistors you added. ;D
Hey Mukhalled, you must use AC to measure the impedance. In this case you also must use several freqs to get a usable measurement, say at 100 Hz, 200 Hz, 400 Hz, 800 Hz and so on, but i would not do it that way, i would have used 3 or 5 amps, one for the subwofer and the others for the other speakers.
//Staigen
//Staigen
A
Alun
- Jan 1, 1970
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You could measure the resistance by connecting to a signal generator and measureing the voltage drop (use a true RMS meter or oscillosope) at differant frequencies when the speakers are connected to it, if you know the internal resistance of the signal generator then it's quite easy to calculate the impedance connected accross it.
audioguru2
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You don't need to measure anything!
Just read the labels on the speakers, use a little common sense and calculate their parallel impedance.
Just read the labels on the speakers, use a little common sense and calculate their parallel impedance.
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