Welcome to the forum. 
Correct.
Efficiency across the majority of the BW is inherent to the drive unit. The enclosure only impacts the LF response. To increase midband efficiency, you'd need a front horn.
Depends on the dimensions of said horn, but a major imbalance in sound pressure levels between the low frequency region and the midband is the most likely result.
Should do.
Difficult to say from the published data, since the HF region is so heavily compressed that it doesn't give a clear idea about how it's behaving. Possibly.
Correct.
Efficiency across the majority of the BW is inherent to the drive unit. The enclosure only impacts the LF response. To increase midband efficiency, you'd need a front horn.
Depends on the dimensions of said horn, but a major imbalance in sound pressure levels between the low frequency region and the midband is the most likely result.
Should do.
Difficult to say from the published data, since the HF region is so heavily compressed that it doesn't give a clear idea about how it's behaving. Possibly.
Thanks for quick response.
Hmmm. So If I could make the horn easily removeable, I could use it or not as desired.
Hmmm. So If I could make the horn easily removeable, I could use it or not as desired.
Good news.
My A7.3's just arrived from Darcher Audio. Dan had been hunting for grey sets for weeks and finally found a few pairs. So I now have all the parts to go ahead with the FH3's.
The only issue is the ply I bought is 19.5 mm thick (measured all the way around).
I have heard mention of needing to change dimensions in one of the build threads but cant find the post(s).
I will have to change some cuts but should I be recalculating all the cuts to maintain exact internal dimensions/volume?
Has anybody already drawn up plans or have the sketchup file so I can adjust it properly? (Winking at you Dave)
Cheers
Dean
My A7.3's just arrived from Darcher Audio. Dan had been hunting for grey sets for weeks and finally found a few pairs. So I now have all the parts to go ahead with the FH3's.
The only issue is the ply I bought is 19.5 mm thick (measured all the way around).
I have heard mention of needing to change dimensions in one of the build threads but cant find the post(s).
I will have to change some cuts but should I be recalculating all the cuts to maintain exact internal dimensions/volume?
Has anybody already drawn up plans or have the sketchup file so I can adjust it properly? (Winking at you Dave)
Cheers
Dean
aesthetics, mostly, but considering the driver mounting height is approx 32" ( 809mm) it also helps with vertical dispersion
Scott could answer more technically, but I think the answer to the second question is: "yes, there are reasons not to change the geometry & CSA of the second section of the folded path"
FH3 is derived from a hypex horn. If you make the front straight, you change the cross section and horn expansion profile; this will in turn alter the gain & functional BW of the box. The dimensions / shape of FH3 generally pull several duties; the sloping front provides the expansion while also angling the driver up slightly, since for some people the mounting height would otherwise be a little low.
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I doubt either will damage anything, and you may or not hear much difference.
Remember the single number listed on the spec sheet is DC resistance. Even the simplest graph of test sweep for T/S parameters will show the wide range of impedance with frequency.
In the case of the A7.3 the REVC = 5.4Ohm, but the impedance curve shows the peak at 70Hz of approx 35 Ohms, a minimum slightly higher than 6 Ohms ad at 300-400 HZ range, a fairly smooth rise that with minor resonant peak at 1500Hz, continuing to approx 12 Ohms at 40K.
Since any driver mounted in an enclosure may likely display different impedance characteristics from the test specs, and music is far more complex than any test signal, there will be few points at which the nominal "match" between any driver and any transformer coupled amp is "perfect" .