Please explain speaker matching crossover + amp

[arjanmaas91]

Hi all,

So lets say I got a amplifier with 2 channels that each put out 50W of power.
I'm planning to hook a 2-way to each channel. And then lets say I found a 50W RMS woofer with just the right specs and a Tweeter with the right specs and same sensitivity.

The tweeter will most likely be something like 10-15W together with a 50W woofer. Maybe that is incorrect but at least not a 50W woofer and a 50W tweeter right?

So if I put a crossover and a 50W woofer and a 15w tweeter on a 50W amp channel, wont the tweeter blow up or something? (im an audio noob).

I mean the crossover does not split the power in 2, they each will get 50W power right? or will the crossover make sure the tweeter gets less?

Basic overall question: How to match speakers with an amplifier when using a 2-way crossover?

 

[eriksquires]

Hi Arj,

The power in music is not evenly distributed. Most of it is in the bass.

In addition, since tweeters are usually more sensitive, you end up burning up some of that power in padding resistors, so at the end of the day, 10 or 20:1 power utilization between the tweeter and woofer is not uncommon.

By this I mean that while playing music if the woofer gets 10 watts, the tweeter itself may only get 1 during a particular musical passage.

Best,


E

 

[Zarathu]

Do it the easy way. Get rid of passive crossovers.

 

[eriksquires]

Do it the easy way. Get rid of passive crossovers.

This in no way helps the original poster answer his question about how to match a tweeter and a woofer.

Best,


E

 

[system7]

Passive crossovers often work well enough... 😀

Here's a design using a 4 ohm woofer and 8 ohm tweeter.
ALTO I | Visaton

It has a lowish 4 ohm impedance at low frequencies, and I'd prefer to use a 8 ohm driver to lift that to nearer 6 ohms. But interestingly that is an off-the-shelf Visaton 3kHz 8 ohm crossover with an 8.2R added for a bit of level reduction on the loudish tweeter.

The project file is here:
Alto I – Boxsim Projektdatenbank

Copy the .bpj to the projekte folder in Boxsim, and you can see how it works:
Software | Visaton

 

[eriksquires]

Arjan,

To finish answering your question, at the bottom, when you are done with a 2-way design, your limiting factors are usually your speaker's sensitivity and the woofer's power handling.

The sensitivity determines how loud the speaker is for a given input. Very sensitive speakers play very loudly with very little input. 5 Watts with a speaker rated at 110 dB efficiency is not unreasonable. Small 2-way monitors are usually in the range of 83 dB or so. They need a lot more power to be listenable. For them, 30-60 Watts is probably a good minimum.

Best,

E

 

[arjanmaas91]

Thanks for all the feedback. Realy usefull information. I finally start to get it more and more 🙂 learned a lot on different forums past few days.

So let me explain what I'm trying to build. I wan't to build a very compact 2.1 bluetooth speaker. I realy aim for a small size yet good quality sound. Volume does not matter to me. If its loud... fine... if its quite for easy listening... also fine 😀

I found this tiny subwoofer:
Tang Band W3-2088S0F 3.5" RBM Micro Subwoofer 4 Ohm
Size: 3.5”
Impedance: 4 ohm
RMS: 25W
PEAK: 50W
FREQ. RESPONSE: 45 to 1000 Hz
SENSITIVITY: 77 dB

I'm trying to match that one with a fitting midrange + tweeter for the left and right channel.

For my first project I used 2 full range drivers and I was not satisfied with the sound... Therefore I want drivers for each individual range (low (1x), mid/fullrange (2x), highs (2x))

So I did a quick search:

Woofer / Fullrange:
Dayton Audio ND65-4 2-1/2" Aluminum Cone Full-Range Neo Driver 4 Ohm
Size: 2.5”
Impedance: 4 ohm
RMS: 15W
PEAK: 30W
FREQ. RESPONSE: 85 to 20.000 Hz
SENSITIVITY: 83 dB

Tweeter:
Dayton Audio ND16FA-6 5/8" Soft Dome Neodymium Tweeter
Size: 5/8”
Impedance: 6 ohm
RMS: 10W
FREQ. RESPONSE: 3.500 to 27.000 Hz
SENSITIVITY: 88 dB

What is your input on this combination? I know it's not the best combo but I struggle to find the perfect one. Maybe I need to find a proper small midrange not a fullrange. Also, maybe this tweeter is still too sensitive? I know the sensitivity of the sub is quite low (at 77db) but it should still add bass to the overall sound right? I bet that sub is still better then just having a fullrange alone. right 😛 ?

I'm just trying to build a 2.1 system around that compact woofer because I like that little thing 😀 not sure if its a smart more. Imput welcome.

 

[AllenB]

The benefit of this 'sub' would be its size. This tends to work against other things, for example efficiency, or bandwidth. The type of enclosure you use would be important in getting satisfactory performance.. in other words deep enough bass and loud enough while considering sensitivity. Why not simulate some, maybe build and see?

 

[eriksquires]

Given how small you are going, you should consider a single driver, full range for the satellites. A FaitalPro 4FE32 is also in this category.

I think with a little googling you can find a number of compact speakers based on single driver FaitalPRO drivers.

Best,

E

 

[arjanmaas91]

Thanks for the input. I will research further 🙂 Maybe indeed a single fullrange is better.

 

[AllenB]

For my first project I used 2 full range drivers and I was not satisfied with the sound...

Maybe you just haven't met one you liked? I have a pair of these in a small system. They can be listened to without equalisation. The problem with full range drivers is that it is difficult to make them well. They can have issues with cone breakup. Sometimes this can be lessened with equalisation.

If you are going to go with tweeters then you might find more is available with dedicated mid/woofers.