Hi guys,
I want to design a crossover with these cheap speakers I bought from Maplins. I would not call them high-end but I want to get my feet wet with designing a good crossover for them and hopefully they should sound OK.
Specs for the speakers.
The woofer
Power: 20W rated / 40W max
Impedance: 6 ohms
Resonant freq. (f.): 125Hz
Output SPL: 84dB @ 1W/1m
The tweeter
Power: 15W rated / 30W max
Impedance: 8 ohm
Resonant freq. (f.): 2kHz
Output SPL: 88dB @ 1W/m
These are all the secs I could find so these speakers. My first question is the
resonant frequency is 2kHz or 125Hz the min or max frequency that these speaker can produce?
I try using this site /http://www.diyaudioandvideo.com/Tutorial/Crossover/
But got confused with the crossover point between the two drivers. What would be a good crossover point for them?
I want to design a crossover with these cheap speakers I bought from Maplins. I would not call them high-end but I want to get my feet wet with designing a good crossover for them and hopefully they should sound OK.
Specs for the speakers.
The woofer
Power: 20W rated / 40W max
Impedance: 6 ohms
Resonant freq. (f.): 125Hz
Output SPL: 84dB @ 1W/1m
The tweeter
Power: 15W rated / 30W max
Impedance: 8 ohm
Resonant freq. (f.): 2kHz
Output SPL: 88dB @ 1W/m
These are all the secs I could find so these speakers. My first question is the
resonant frequency is 2kHz or 125Hz the min or max frequency that these speaker can produce?
I try using this site /http://www.diyaudioandvideo.com/Tutorial/Crossover/
But got confused with the crossover point between the two drivers. What would be a good crossover point for them?
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re:'These are all the specs I could find so these speakers' - well, that's not enough info,
you'll need to either learn to measure speaker parameters, or easier for you is to use speakers that have all parameters provided, along with frequency & impedance plots.
re:' Resonant freq. (f.): 125Hz' it's a big stretch to call a driver with a resonant frequency of 125 Hz a 'woofer'; it's more suited to mid range use.
Resonant frequency usually has some relationship to the lowest frequency produced, for woofers it's around the resonant freq; for tweeters its approx an octave higher (2x Fs)
re:'What would be a good crossover point for them? ' at a minimum,you need frequency response graphs to make that decision
you'll need to either learn to measure speaker parameters, or easier for you is to use speakers that have all parameters provided, along with frequency & impedance plots.
re:' Resonant freq. (f.): 125Hz' it's a big stretch to call a driver with a resonant frequency of 125 Hz a 'woofer'; it's more suited to mid range use.
Resonant frequency usually has some relationship to the lowest frequency produced, for woofers it's around the resonant freq; for tweeters its approx an octave higher (2x Fs)
re:'What would be a good crossover point for them? ' at a minimum,you need frequency response graphs to make that decision
After looking on the Maplins website I found the data sheets for both drivers. They have the frequency response graphs and some other information.
The woofer its indeed a mid-range speaker but advertised as a bass / mid-range driver.
Data sheet for the mid-range: http://www.maplin.co.uk/media/pdfs/L68AW.pdf
Data sheet for the tweeter:
http://www.maplin.co.uk/media/pdfs/L65AW.pdf
From the datasheet I can gather the mid-range is poor at low frequency sounds but can play higher frequency sounds pretty well. Its starts to drop off around 2000 khz so could this be a good crossover point?
The woofer its indeed a mid-range speaker but advertised as a bass / mid-range driver.
Data sheet for the mid-range: http://www.maplin.co.uk/media/pdfs/L68AW.pdf
Data sheet for the tweeter:
http://www.maplin.co.uk/media/pdfs/L65AW.pdf
From the datasheet I can gather the mid-range is poor at low frequency sounds but can play higher frequency sounds pretty well. Its starts to drop off around 2000 khz so could this be a good crossover point?
if those were ( near as ) perfect components , for medium-low listening volume a 1st order crossover would suffice ; but the woofer is indeed a midrange , so to make it together with the tweeter it would mean to shift the overall point of where the presence ( not the preSence in the tone control nomenclature ) of sound, its warmth , is located , which just happen to be in the 100-400 Hz region 
So another rambling in search of the final touch , a real woofer , would
make sensible improvements in such a project
So another rambling in search of the final touch , a real woofer , would
make sensible improvements in such a project
You asked what a good crossover frequency would be and I'd suggest 4 or 5kHz would be good for a first attempt.
You will need to reduce the level of the tweeter as it will be too loud otherwise, and you may want to apply some extra reduction to the woofer's higher frequencies in response to something called the 'baffle step'.
You will need to reduce the level of the tweeter as it will be too loud otherwise, and you may want to apply some extra reduction to the woofer's higher frequencies in response to something called the 'baffle step'.
Haz , The first part of your reply goes against the second part . I thought you were talking about woofer to midrange cutoff freq .
In that way , it sounded reasonable !
I was reading some days ago in this forum about difference in 2 and 3 way
design ( ...considerations) , and eventually it isn't written anywhere that a 2 way it's easier than a 3 way , considering that to allow a good bass reproduction you have to take into account that a speaker is a passband device and there's a strict relation to cone diameter , low freq. and power , so to tailor a crossover and the drivers to a baffle is just a matter of projecting what you need.
The first part of your reply goes against the second part . I thought you were talking about woofer to midrange cutoff freq .In that way , it sounded reasonable !
I was reading some days ago in this forum about difference in 2 and 3 way
design ( ...considerations) , and eventually it isn't written anywhere that a 2 way it's easier than a 3 way , considering that to allow a good bass reproduction you have to take into account that a speaker is a passband device and there's a strict relation to cone diameter , low freq. and power , so to tailor a crossover and the drivers to a baffle is just a matter of projecting what you need.
That's a typical midrange , I guess !
Haz ,
In that way , it sounded reasonable !
I was reading some days ago in this forum about difference in 2 and 3 way
design ( ...considerations) , and eventually it isn't written anywhere that a 2 way it's easier than a 3 way , considering that to allow a good bass reproduction you have to take into account that a speaker is a passband device and there's a strict relation to cone diameter , low freq. and power , so to tailor a crossover and the drivers to a baffle is just a matter of projecting what you need.
That's a typical midrange , I guess !
Sorry for being a little sorry on this subject I simply want to design a simple crossover for these two drivers for a TDA7000 and TA2024 type fm radio I don't really care for the bass that much.
A few days ago all I knew about a crossover was that it separated different frequencies to make them suitable for a typical driver. These drivers are probably a little overkill for the job but I thought it would be fun to use a 2 way speaker setup. A full-range driver connected directly to the TA2024 its no doubt easier but I'm not going to learn anything new by doing that
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To begin with the tweeters appear to be approximately 4-5dB louder than the woofers.
Now, you have dismissed the importance of bass for your intended use. I can accept that, but it will be important that you create the right balance in the lower midrange/upper bass region so at least the vocal region will be reasonably weighted. Although this should be measured, you might guess at losing another few dB toward the top of the woofer range.
With a combined total of over 6dB of tweeter sensitivity to burn, You may be best using an L-pad which requires 2 resistors placed after your high-pass filter.
By the way if I might put my tuppence in, the woofer has a peak at 1kHz and it would take an inductor, a capacitor and a resistor to fix. It is in a reasonably sensitive region so may be worthy of some attention. I could see other ways out of it, such as crossing closer to 2kHz requiring a more substantial tweeter.
This woofer may sound good, with or without any changes. To cut to the point though it costs to deal with issues like this and this money is better spent on a woofer that is simpler to work with. That said though they certainly don't need to be special or extravagant to sound good.
Feel free to overlook this for the time being as it should be easy enough to correct afterward. The same could almost be said about baffle compensation in this case.
Well, you have to give Maplin credit for truth in advertising - those spec sheets make the drivers look like rubbish, I did a quick sim of the mid driver, which confirmed this....
it will work best in an open backed box or open baffle.
Try a simple single cap xover, to attenuate the tweeter you can use this calculator:
L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker voltage divider - sengpielaudio Sengpiel Berlin
Let us know how they sound, it's always a challenge to make a silk purse...., & you never know, they might just sound OK... (but I wouldn't put money on it...)
it will work best in an open backed box or open baffle.
Try a simple single cap xover, to attenuate the tweeter you can use this calculator:
L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker voltage divider - sengpielaudio Sengpiel Berlin
Let us know how they sound, it's always a challenge to make a silk purse...., & you never know, they might just sound OK... (but I wouldn't put money on it...)
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I'm having some problems finding the 0.24 mH inductor for the crossover. So I'm going to try and make one, I've seen some 22 SWG enamelled copper Wire on ebay priced per meter. Hopefully 22 SWG is thick enough.
If I wind it around a one inch former 44 times I should get around 0.24 mH for the 4khz crossover frequency. I have an inductance meter so I can wind and measure as I go. Will let you know how that turns out.
If I wind it around a one inch former 44 times I should get around 0.24 mH for the 4khz crossover frequency. I have an inductance meter so I can wind and measure as I go. Will let you know how that turns out.
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