Rignt-o but without the side "diffusion" they are best wide, with the side "diffusion" I found that vertical gives a much tighter and clearer image... of course if you have a very reflective ceiling and/or floor something needs to be done about that... in the room in the pix the ceiling was very very high, so no prob... otherwise absorption is required imo.
_-_-bear
_-_-bear
Why not a 'A7-Onken' hybrid?
Hope it's ok to bring this back up...
I can't read the language but here's a hybrid altec FLH-onken I thought was interesting...
Which is actually just a variation on the Altec 816vi, I guess.
Any thoughts on how a hybrid like this might work?
My thought would be that maybe the floor loading ports of the other altec FLHs might be better, but I've never heard any of them.
Sorry if I'm a bit slow, but just to verify what I think I'm hearing from the various threads on the Altec FLHs is that they're best if you can back away from them a bit?
I've got a got a big room with vaulted ceilings thats hard to fill with sound but the physical layout (not furniture etc) of the house forces you kind of close to the speakers. So I'm thinking maybe fonkens might better?
And how 'axis-critical' is it? Especially relatively near field?
They say it was designed for situations where 'directivity' is a concern... So I was just wondering?
Thanks,
Phil
Hope it's ok to bring this back up...
I can't read the language but here's a hybrid altec FLH-onken I thought was interesting...
An externally hosted image should be here but it was not working when we last tested it.
Which is actually just a variation on the Altec 816vi, I guess.
An externally hosted image should be here but it was not working when we last tested it.
Any thoughts on how a hybrid like this might work?
My thought would be that maybe the floor loading ports of the other altec FLHs might be better, but I've never heard any of them.
Sorry if I'm a bit slow, but just to verify what I think I'm hearing from the various threads on the Altec FLHs is that they're best if you can back away from them a bit?
I've got a got a big room with vaulted ceilings thats hard to fill with sound but the physical layout (not furniture etc) of the house forces you kind of close to the speakers. So I'm thinking maybe fonkens might better?
And how 'axis-critical' is it? Especially relatively near field?
They say it was designed for situations where 'directivity' is a concern... So I was just wondering?
Thanks,
Phil
How important are the following goals.
Br area 85-90% Sd
Port length < 35cm = 1,16ft
Tuning can be adjusted to driver in my opinion, and when port length is more then 1ft or Br area < 80% cant make to much difference still be a good onken.
Can some one say something about how important this is?
It has some thing to do to have the same air mass in the port is the same as in the box. That is the goal in the onken design?
can not believe when you are a little of that figure it doesn't sound the same.
Br area 85-90% Sd
Port length < 35cm = 1,16ft
Tuning can be adjusted to driver in my opinion, and when port length is more then 1ft or Br area < 80% cant make to much difference still be a good onken.
Can some one say something about how important this is?
It has some thing to do to have the same air mass in the port is the same as in the box. That is the goal in the onken design?
can not believe when you are a little of that figure it doesn't sound the same.
Correct, which is just a '50s era Jensen Ultra-flex reflex loading style which in turn is just a rectangular variation of one of Thuras's examples defined in his original 1932 reflex patent, so if you want to build an original you'll have to ring thirteen pipe vents around the driver as close as physically practical to create an acoustically larger radiator at Fb.
Combination alignments (reflex loaded FLH) were created to extend a truncated horn's LF response, so when done correctly its tuning is actually quite under-damped (peaking) to ~flatten its summed response as well as protect the driver below the horn's loading.
When originally designed, amps had a high output impedance which helps in this regard, so if not re-tuned to a higher Fb when driven with a very low output impedance there's an audible step down in response that in a home or some installed venue apps can be compensated for by corner loading.
WRT vent positioning: http://www.diyaudio.com/forums/subwoofers/176209-help-evaluation-first-sub-build.html#post2353040
In short, the sonic difference is in how the vent system affects the speaker's summed output higher up in frequency above Fb which is in turn further out of phase with the driver's front radiation.
FLHs get their gain from focusing the driver's acoustic power response over a narrower arc, so if we visualize a single complete frequency (1 WL) as a soap bubble of 'x' diameter, then as we squeeze it into an increasingly oblong shape one must be further away with increasing directivity to keep from being engulfed by it ('near-field'), so the narrower the horn's polar pattern (higher directivity factor Q) the farther one must sit to be in its far-field where the 'fullness' of its output will be felt.
IOW, like line arrays, a compression horn's response doesn't initially follow a point source's 1st order shelving response over distance, so in a typical HIFI/HT app this delay offset must be accounted for in a woofer/compression horn speaker alignment for best overall performance on vertical axis since one is normally in the horn's near-field through the XO's BW.
The 'best' HIFI/HT speaker alignment for a given app has many variables (not the least of which is personal preference/WAF) and since this subject has been expoundeded on pretty much continuously on the forums in one way or another by numerous folks I'll leave it to the 'gentle reader' to do their own research to form an opinion of their own as to what might work best for them. That, or start a new thread with full details of your room, electronics, any limitations such as listening position, speaker size, placement, WAF restrictions/whatever for folks to offer an opinion and/or some technical insight.
A compression horn's power response narrows with increasing frequency, so as a general rule-of-thumb (ROT), as one moves off axis horizontally, its useful HF BW is limited to where the throat starts becoming shrouded from view, so typically must be toe'd in and since it does, it normally sounds best overall if over-toe'd, i.e. their on axis responses cross somewhat in front of the listening position's 'sweet spot', same as with typical 'FR' driver speakers which have similar power horizontal (polar) responses.
From this we see that the longer the listening distance, the narrower the power response needs to ideally be to keep early reflections from occurring in front of it, ergo the shorter it is, the wider it must be, so the horn either must get bigger in area with a 'faster' expansion or get rid of it altogether and use an appropriate size point source driver to get the desired coverage angle and why the pioneers of audio designed huge horns for huge spaces and shrunk them down for smaller venues with either a two way separate mid/HF horn, woofer combo or HF horn/woofer co-ax being used for recording studio, broadcasting, HIFI or similar acoustically small room apps to keep it size as small as practical.
All that said, best to avoid using any parallel horn walls for high SQ HIFI/HT apps as the only way to quell its long term obnoxious (IME) eigenmodes (standing waves) also excessively damps down its output.
GM
The Jensen Ultra-flex/Onken's rigid requirements are based on Thuras's patent application 'proof-of-concept' which he allegedly chose to keep his math as simple as practical, so in the scheme of things, better overall performance (least harmonic distortion WRT allowable vent compression) is to use T/S to design a single vent based on a < 5% vent mach at design power which will typically be < Onken's minimum vent area and if you want to mimic its 'rich' (distorted) harmonic structure/style, then IME, design using multiple vents and let your ears decide what the max tolerable vent length is for a given app or accept this ROT from Dan Wiggins as an acceptable one:
Lmax = 13,560"/(20*Fb)
Where
Lmax is in inches
Fb is the tuning frequency in Hz
GM
T/S = Thiele/Small = use Fs, Vas, Qts, etc. in WinISD Pro or other vented alignment design program
< = less than
< 5% vent mach = less than 5% of the speed of sound (SoS) = ~1129 ft/sec (~344 m/sec) = ~56.45 ft/sec (~17.2 m/sec)
design power = how much peak power the actual box tuning (Fb) is likely going to need available. If unknown, then use either the amount of power that moves the driver to Xmax in a computer simulation or the amp's peak power rating, whichever is lower
GM
< = less than
< 5% vent mach = less than 5% of the speed of sound (SoS) = ~1129 ft/sec (~344 m/sec) = ~56.45 ft/sec (~17.2 m/sec)
design power = how much peak power the actual box tuning (Fb) is likely going to need available. If unknown, then use either the amount of power that moves the driver to Xmax in a computer simulation or the amp's peak power rating, whichever is lower
GM
Correct, the Onken alignment has too much harmonic distortion to call it high sound quality (SQ) no matter how euphonic it may sound to some folks. They sure look cool though!
One aspect of it that I forgot to address earlier is its better driver damping due to all that vent volume creating in effect a crude two stage TL, so to 'have your cake and eat it too', instead do a vented TL (MLTL). I compared an Altec 416-8C Onken (n = 5.7) with vent area (Av) = driver effective area (Sd) to a comparable MLTL and while the Onken was a lively performer, the MLTL with its single smaller, shorter vent sounded just as open/dynamic, yet smooth as a baby's bottom with a better perceived transient response.
Consequently, the Onken's owner copied my MLTL design except added fake Onken vents because he liked the look so much, but the single 8" diameter vent was actually in the back. Internally, it was folded in half to form an inverted 'U' get the TL's high aspect ratio.
GM
One aspect of it that I forgot to address earlier is its better driver damping due to all that vent volume creating in effect a crude two stage TL, so to 'have your cake and eat it too', instead do a vented TL (MLTL). I compared an Altec 416-8C Onken (n = 5.7) with vent area (Av) = driver effective area (Sd) to a comparable MLTL and while the Onken was a lively performer, the MLTL with its single smaller, shorter vent sounded just as open/dynamic, yet smooth as a baby's bottom with a better perceived transient response.
Consequently, the Onken's owner copied my MLTL design except added fake Onken vents because he liked the look so much, but the single 8" diameter vent was actually in the back. Internally, it was folded in half to form an inverted 'U' get the TL's high aspect ratio.
GM
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