Interested in better understanding this notion. What kind of waveguide and what would the waveguide do for this? Have an effect on the higher part of the range or the lower end of this range (my understanding is a horn would be needed for this).
Following this approach, I wonder how high an 8" mid woofer could be good at.
There's nothing really much to it, Geddes speakers all follow the same basic principle.
A 6" woofer with a 6" waveguide have pretty much the same directivity profile. That is the woofer starts to beam as the waveguide starts to control the tweeters directivity. These two overlap/match in frequency. The ideal is to pick a woofer that can cross over during this narrowing of directivity and crossover to the tweeter around this point. So for a 6" driver you would want to cross over around 2200-2500Hz.
An 12" would better suit 1100Hz cover as mentioned above, but it'd be done with a 10" too provided the tweeter on waveguide could handle it.
An 8" would do well crossed around 1700Hz.
Most metal cone drivers do not suit this approach because they need lower xovers to mitigate their harmonic distortion peaks. You can get around this by crossing over before the woofer starts to beam but it places additional demand on the tweeter so you need something that can cope.
A driver that bucks this trend is the SB17NAC with it's ribbed metal cone and lack of harmonic distortion peaks.
This is probably getting off topic although I suppose it is relevant to the use of large PA mids and mid bass drivers.
The famous JBL engineer Drew Daniels offered up an all-out system design with the JBL high eff midrange 2123H at its core:
Untitled
This is well worth reading! Note his comments about using a cylinder enclosure 1 foot deep and filled with fiberglass (and ONLY fiberglass!!!) as being crucial to extracting the best from the 2123H or the subsequent, still higher quality JBL 2012H.
Fwiw.
I cannot attest to this personally, but I plan to try a short transmission loading with a ready-made 4 foot folded t-line by Obcon Single 10" Labyrinth from eBay. I'll be using the 18SOUND 10NDA520 with some UltraTouch recycled cotton insulation.
Alex
Untitled
This is well worth reading! Note his comments about using a cylinder enclosure 1 foot deep and filled with fiberglass (and ONLY fiberglass!!!) as being crucial to extracting the best from the 2123H or the subsequent, still higher quality JBL 2012H.
Fwiw.
I cannot attest to this personally, but I plan to try a short transmission loading with a ready-made 4 foot folded t-line by Obcon Single 10" Labyrinth from eBay. I'll be using the 18SOUND 10NDA520 with some UltraTouch recycled cotton insulation.
Alex
I agree they are pretty good. The 10FH530 had the least variance in it's frequency response compared to the rest! I just like the other ones better from a harmonic distortion standpoint.
Thank you 5th elemen.
I got two RCF 10L-750YK and they are excellent in the range 175-1100hz.
Very open and clear sound.
I had thought about acquiring a pair of those, but the limited Xmax kept me away from them, as well as a limited F(-3) point. Have you tested the harmonic distortion of those?
Looking forward to it, have my eyes on this for quite some time, plan to mate it with the TPL150H in a stand mount I have in mind.
T/S Parameters for the Beyma 10MC700Nd. Unit was cold, but it was already broken in at full-Xmax with a 20Hz sine wave for 1 hour. T/S parameters did not shift much after break-in, which to me is good because it says the sound character should be consistent either way. For all practical purposes, they are reasonably identical.
