3-way speaker system

nakyung

Member
2020-03-08 1:42 pm
Hi guys, I'm new to this forum and to audio, and I want to ask something about the 3 way speaker.

I recently restored a 20 y/o 3 way speaker system and the drivers are, as we know, have deteriorated, so I decided to replace them.
It originally has a 3" tweeter, a 5" midrange, and a 10" woofer. The tweeter still sounds good, but the other two doesn't. I replaced the midrange and woofer with 5" woofer and 10" woofer respectively.

Guess what, it sounds ok but definitely missing something, probably the midrange. Is there anything I can do to improve the sound? Probably replacing the woofer with midrange?

Important to note, the speaker system has NO crossover, and I'm thinking about adding one. Does two woofers in one enclosure sound bad?
 
It's important to know the impedance of each driver, 4 ohms or 8 ohms and from there maybe going with and old school 3-way Pionner crossover that had only a cap for each driver. One for mids (?)and another capacitor for the tweeter (?). That's only an estimated guess of a basic (working) crossover that can play, not hifi. Of course it's an art building a crossover and requires pictures of the drivers and knowing the model and measuring and testing.
 

Galu

Member
2018-04-17 6:50 pm
You gotta have a crossover! :eek: As Inductor says, at the very least there has to be a capacitor in series with the mid and a smaller value cap in series with the treble.

A crossover calculator like this 1st Order 3 Way X-over Calculator - KBapps.com will show you a slightly more sophisticated crossover schematic.

Ideally you should have a dedicated midrange speaker and, if its back is not self-enclosed, it should be in its own sub-enclosure inside the main enclosure to protect it from the back pressure of the 10" woofer.
 

nakyung

Member
2020-03-08 1:42 pm
All of my drivers are 8 ohm, paired with 8-16 ohm amplifier. On ghr tweeter, of course I wired a cap in series.

Putting a cap on the 5" woofer? That sounds good, but AFAIK, when you wire a cap on a speaker, it reduces the bass output, and so does the volume, CMIIW. I tested another 3" woofer with various caps with different values and the result is different too. Small capacitance cap, for example the 4.7 uF, reduces bass and volume the most, while another cap at 470 uF, it does almost nothing, bass and volume the same.
 

Galu

Member
2018-04-17 6:50 pm
Putting a cap on the 5" woofer? That sounds good, but AFAIK, when you wire a cap on a speaker, it reduces the bass output, and so does the volume
Best not to let the 5" driver handle the bass frequencies - leave that up to the 10" woofer.

A series capacitor acts as a filter, blocking the lower frequencies while letting the higher frequencies through.

The smaller the value of the capacitor in uF, the more the lower frequencies are blocked.

A typical value for the tweeter is 2.2uF, but the midrange needs to operate lower down the frequency range so a larger value of, say, 10uF or 12uF is typical.

Remember also that the 5" driver, if open at the back, must be physically protected from the back pressure of the 10" woofer, as I described earlier.
 

Galu

Member
2018-04-17 6:50 pm
Guess what, it sounds ok but definitely missing something, probably the midrange. Is there anything I can do to improve the sound? Probably replacing the woofer with midrange?
Your 5" woofer is probably not sensitive (loud) enough in the midrange frequencies to match the bass output of the 10" woofer.

You really need a dedicated midrange unit (not a woofer) which is sensitive enough to match the 10" woofer.

If you can provide details (preferably links to) your three separate drivers, that would be most helpful.
 

nakyung

Member
2020-03-08 1:42 pm
Thanks for the suggestions @Galu. I bought local made drivers (made in my country) and on the site, it doesn't really mention the full specs, only power and impedance.

After all, I'll have to reconsider about what im going to do later. Still a newbie in audio.
 

Galu

Member
2018-04-17 6:50 pm
Thanks nakyung!

And, since you're a newbie, let me remind you that the capacitors must be non polar (NP) types intended for use in loudspeaker crossovers.

Plastic film types, such as polypropylene, are always NP - see attached image.

"while another cap at 470 uF, it does almost nothing"
A 470uF capacitor will almost cerainly be a polar capacitor (one end + and the other end -) and these types must not be used in loudspeaker crossovers.

You've got some research to do on multi-way louspeakers, but I hope to see you back with more DIY questions in the future. :)
 

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