I was offered these DIY builds "for parts". What have I got here?

[phantompowered]

 

[suttondesign]

A speaker with weird directionality. Omni for a while from low to mids, beams in the mid, then is wider again in the highs?

 

[phantompowered]

A speaker with weird directionality. Omni for a while from low to mids, beams in the mid, then is wider again in the highs?

How exactly would you surmise this?

 

[suttondesign]

the nature of large drivers is to beam according to a certain formula. you can look up the calculations. i have no idea of the tweeter’s characteristics, but you can look it up on the morel site.

 

[alex-z]

I would pass on those. Whoever built them put a lot of care into the cabinet finish and none into the speaker design.

Huge directivity mismatch between the woofer and tweeter due to their size. Tweeter isn't flush mounted, so there is unnecessary diffraction. The tweeter should be closer to the woofer for a broader vertical sweet spot.

 

[Wolf]

Looks like a Morel MW144, a 5" woofer.
The tweeters look like older Peerless 1" domes. I have some MDT40s, and they look a little different than those.

 

[ChrisG]

There are many possible directivity plots here, depending on the crossover point and slope. The people further up are making assumptions, but we don't have all of the information.

Some examples:
- A "textbook" approach of, say, 2nd (or higher) order at 3kHz would result in the usual "Christmas Tree" shaped directivity plot in the horizontal plane, where the woofer gets narrow before the tweeter is wide again. In the vertical plane, you're subject to the usual lobing at/near the crossover point.
- A shallow highpass filter would allow the tweeter to contribute some energy lower down in the frequency range. Result: much better horizontal directivity, but the vertical lobing is now happening over a wider range. There may be a harmonic distortion penality, depending on how well the tweeter copes with handling content down into the midrange.
- The crossover point may be relatively high, close to where the tweeter is starting to exhibit directivity of its own. Handled correctly, direct radiators can produce a relatively narrow beamwidth used this way.
- Finally, a low-but-steep crossover (say, 1kHz, 4th order) would result in a consistent (wide) directivity, since we're crossing over before the midbass gets narrow. Again, harmonic distortion/power handling penalty against the tweeter.


I agree with those that say the tweeter ought to be flush-mounted. It's possible that the vertical spacing has been chosen for a particular reason, but we don't know for sure.


Chris

PS - I'd ask that the "minor voice coil problem" is fixed before considering purchase. If it's minor, the seller won't mind sorting it for you.

 

[audio_tony]

I had a pair of speakers built around those drivers - they are excellent drivers.

 

[phantompowered]

There are many possible directivity plots here, depending on the crossover point and slope. The people further up are making assumptions, but we don't have all of the information.

Some examples:
- A "textbook" approach of, say, 2nd (or higher) order at 3kHz would result in the usual "Christmas Tree" shaped directivity plot in the horizontal plane, where the woofer gets narrow before the tweeter is wide again. In the vertical plane, you're subject to the usual lobing at/near the crossover point.
- A shallow highpass filter would allow the tweeter to contribute some energy lower down in the frequency range. Result: much better horizontal directivity, but the vertical lobing is now happening over a wider range. There may be a harmonic distortion penality, depending on how well the tweeter copes with handling content down into the midrange.
- The crossover point may be relatively high, close to where the tweeter is starting to exhibit directivity of its own. Handled correctly, direct radiators can produce a relatively narrow beamwidth used this way.
- Finally, a low-but-steep crossover (say, 1kHz, 4th order) would result in a consistent (wide) directivity, since we're crossing over before the midbass gets narrow. Again, harmonic distortion/power handling penalty against the tweeter.


I agree with those that say the tweeter ought to be flush-mounted. It's possible that the vertical spacing has been chosen for a particular reason, but we don't know for sure.


Chris

PS - I'd ask that the "minor voice coil problem" is fixed before considering purchase. If it's minor, the seller won't mind sorting it for you.

Thank you. The "seller" is a friend from my bike club who is happy to simply give them to me for nothing, so I am not concerned about the potential problems with the voice coil. If it's minor enough I am happy to tinker with it also.