Thanks very much Pano 
. Request mods to delete my previous 3 posts.
Here is fresh query. Three questions I would like to know.
I took the test again with another amplifier module that I have. Low tones sample file results were approx. 0.1, 0.2, 0.4, 0.7, 0.9 V. I was under impression that low frequencies at same level would require more power. Which I am not getting compared to 120hz test file. (1) Why ?
I wanted to see if one has 3 way speakers can one power the tweeter and midrange with Class A amplifier and woofer with more powerfull amplifier keeping the original crossover. it saves us from having to make active crossover. Which would require more electronics, one more stage in front and crossover re-calculations. Besides crossover power loss is distributed amongst two amplifiers.
lets say my test results for 120hz is 1.7volts. 1.7x1.7 = 2.8 (approx 3Watts) Now for peaks I multiply test volt with 4 . so 1.7x4 = 6.8volts. To convert to watts 6.8x6.8 = 46watts. Rounded to 50 watts amplifier is what I need for that particular 3 way speaker at that particular volume.
(2) So second question I ask is in typical 3 way speakers what would be power requirement distribution amongst the three drivers ? I know its little difficult to calculate without knowing crossover and driver impedance etc. But any rough estimate would do.
(3) OR can I do it like this ? At same volume level I run a frequency sweep and measure maximum voltages on each driver ?
Regards
. Request mods to delete my previous 3 posts. Here is fresh query. Three questions I would like to know.
I took the test again with another amplifier module that I have. Low tones sample file results were approx. 0.1, 0.2, 0.4, 0.7, 0.9 V. I was under impression that low frequencies at same level would require more power. Which I am not getting compared to 120hz test file. (1) Why ?
I wanted to see if one has 3 way speakers can one power the tweeter and midrange with Class A amplifier and woofer with more powerfull amplifier keeping the original crossover. it saves us from having to make active crossover. Which would require more electronics, one more stage in front and crossover re-calculations. Besides crossover power loss is distributed amongst two amplifiers.
lets say my test results for 120hz is 1.7volts. 1.7x1.7 = 2.8 (approx 3Watts) Now for peaks I multiply test volt with 4 . so 1.7x4 = 6.8volts. To convert to watts 6.8x6.8 = 46watts. Rounded to 50 watts amplifier is what I need for that particular 3 way speaker at that particular volume.
(2) So second question I ask is in typical 3 way speakers what would be power requirement distribution amongst the three drivers ? I know its little difficult to calculate without knowing crossover and driver impedance etc. But any rough estimate would do.
(3) OR can I do it like this ? At same volume level I run a frequency sweep and measure maximum voltages on each driver ?
Regards
OK, now I understand what you are trying to achieve.
In a 3-way passive speaker the woofer is almost always the least sensitive driver. The midrange and tweeter will match it or, more likely, but attenuated to match the woofer. So if you find your loudest playback level and measure the test tones you will know how much voltage you need for the woofer.
The mid and the tweeter are attenuated, so they also need the same voltage as the woofer. If you split the system with one amp on the woofer and another amp on the mid+tweet, both amps would need to output the same voltage. That would only change if you remove the attenuation from the mid and tweeter.
Is removing the attenuation a good idea? Only if you know what you are doing and understand the crossover. The filter curves a likely calculated with the attenuation in place. If you remove the attenuation, you will change the impedance seen by the crossover and thus the filter function of the crossover. It won't sound the same.
Do you know what the drivers are and what the crossover is? If so, you should start a thread and ask for help to reconfigure the crossovers for dual amp use.
In a 3-way passive speaker the woofer is almost always the least sensitive driver. The midrange and tweeter will match it or, more likely, but attenuated to match the woofer. So if you find your loudest playback level and measure the test tones you will know how much voltage you need for the woofer.
The mid and the tweeter are attenuated, so they also need the same voltage as the woofer. If you split the system with one amp on the woofer and another amp on the mid+tweet, both amps would need to output the same voltage. That would only change if you remove the attenuation from the mid and tweeter.
Is removing the attenuation a good idea? Only if you know what you are doing and understand the crossover. The filter curves a likely calculated with the attenuation in place. If you remove the attenuation, you will change the impedance seen by the crossover and thus the filter function of the crossover. It won't sound the same.
Do you know what the drivers are and what the crossover is? If so, you should start a thread and ask for help to reconfigure the crossovers for dual amp use.
ahh! got that. forgot different drivers need attenuation to match. A friend will be giving me Sony bookshelf speakers soon to experiment. He said they are two ways with separate tweeter. But we are again in lockdown for a week so cant visit him. Will update.
Any idea why am I getting low voltages compared to 120hz on low tones sample file ?
regards.
Any idea why am I getting low voltages compared to 120hz on low tones sample file ?
regards.
Out of a normal CD player you should get 700 mV. That's assuming it has a 2V RMS output like most players. And that's also assuming that your meter is linear over that range of tones. It might not be.
It is a good idea for you to check each step along the way. While you do that, I'll double check my test signals, it's been a few years since I uploaded them.
EDIT: Fixed mV level
It is a good idea for you to check each step along the way. While you do that, I'll double check my test signals, it's been a few years since I uploaded them.
EDIT: Fixed mV level
If you don't need the extra headroom of the Aleph 4, I can understand that the J would do better for you.
@Hiten. I checked the Low Tones MP3 and it is correct. 25, 30, 40, 50, 60 Hz. All at -12dBFS. That would be 9dB below the loudest sine wave possible. Meaning that you should get about 710mV from you source.
Whatever you get, it should all be the same. But as your measurements show an increasing voltage as the frequency rises to 60Hz, that indicates a high pass filter somewhere in your signal path. It could be your meter, your source, your preamp or you amp. It could even be a combination of those.
I would suggest measuring the low tones (25, 30, 40, 50, 60 Hz) then measuring the 120Hz and 240Hz signals. This will help show the frequency of your high pass filter.
Whatever you get, it should all be the same. But as your measurements show an increasing voltage as the frequency rises to 60Hz, that indicates a high pass filter somewhere in your signal path. It could be your meter, your source, your preamp or you amp. It could even be a combination of those.
I would suggest measuring the low tones (25, 30, 40, 50, 60 Hz) then measuring the 120Hz and 240Hz signals. This will help show the frequency of your high pass filter.
I measured the line out of my cd player. for low tones I am getting (46, 66, 117, 182, 250 mv). For 120hz I am getting (610mv). for 220hz I am getting (730mv.)
I am suspicious about my cheap tda7498 module. It may have high pass filter. Sample here.
sorry if I am bothering you with minor issues. I will check this thread if other have posted low tone measurements. But (ignoring my measurements) generally I presume for lowtones tests I should get higher volts measurement than 120 and 220hz tones. Correct ?
thanks and regards.
I am suspicious about my cheap tda7498 module. It may have high pass filter. Sample here.
sorry if I am bothering you with minor issues. I will check this thread if other have posted low tone measurements. But (ignoring my measurements) generally I presume for lowtones tests I should get higher volts measurement than 120 and 220hz tones. Correct ?
thanks and regards.
Yes. This thread is a revelation. Normally I listen normal low level. For this test I cranked up the volume. And I am listening around 3 watts maximum. Even if peaks are considered 40/50 watt amplifier would be sufficient I think.
Regards.
addition : I was also wondering if we should even worry about peaks. Since most speakers have 1 - 3 % distortion at peaks/transients we would still get distortion(if we listen loud). So in my case It would even be ok to have 20/30 watt amp. And probably a circuit implementation to soft clip the transients to make it sounds good ?
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Something is not right here. Either your CD player has a major high pass filter, or your meter does. I suspect the meter. Can you check another player? Computer, phone, iPod? Anything that will play MP3 and have a line output.