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In the Forum: Horn-Loaded Speakers
In the Thread: Eventually - a reasonable midbass horn from GOTO
Post Subject: More goto...Posted by Jeffrey Jackson on: 12/11/2007
Hello again, Romy... friends.. cats...
I am sorry for my delinquence in replying... but the good news is that in the past weeks I have managed to get a beginning Goto system together... more on that in a minute..
first, basshorns... the basshorns that I posted here some years back are my straight ~50Hz horns (my memory is fading)... they are 8' long... then rear chamber.. mouth ~ 3' x 4'... throat ~8" x 8"... rear chambers of various sizes and some partially filled with blocks of wood as I tuned resonance... so yes, I also have quite a bit of experience with woofers in midbass horns *with compression* and tuning for optimal results.. measured and listening... I feel that you *must* do both... the one thing that I wish I would have tried was a simple phase plug.. that seems to be the thing that "real" compression drivers have that we don't.. it would be easy.. just turn one from wood... suspend with long screws... of course, this needs to be factored into the horn flare... it adds length, but as we discussed, most midbass horns need more length, not less... and then there is the issue of how much compression.. sigh.. so many variables...
one place that my findings were different from yours was in field coil drivers in my midbass horn... I found that in my application (Jensen F12N) a stronger field really helped the sound... more clarity in the upper reaches of the horn... I have rationalized this as the stronger field is driving Qes down....
oh.. and the double driver being "better" than one... I should really retract that statement.. I did state that I had not personally tried this, and I personally don't like the idea of doing this in the midrange and up, but that two friends had tried this and liked it... I would like to retract it as I am unsure of how much of a fair A>B comparison it was... certainly the horn length changed.. did they adjust the mouth back so that the blend at the crossover frequency was the same? adjust for the new impedance? how do we not know the amp wasn't happier with the new load? it certainly would change the distortion spectra... so, too many variables to pass this on as fact...
so.. now to my new quick and dirty Goto setup... as I began above, I am no longer using my pair of straight basshorns.. I will be constructing something new soon... not sure what just yet.. thinking similar to what I had, but more "wife friendly"... I have moved out of my shop and have to be a bit more domesticated.. but that is a small price to pay to have one of my horn systems in the house again.. ahhh....
so here it is...
JBL 2405 ~7k up
Goto 370 on 600 horn ~1k to 7k
Goto 505 on 150 horn ~220 to 1k
Sealed box 15 ~220 down
(old Pioneer with cast frame, paper cone, and linen surround)
at the moment I am biamping with speaker level crossovers.. Eimac 75tl on horns and SE845 on woofers... I have so many "next steps", but likely next will be to line level cross... then new horns for Goto drivers.. then basshorns.. but I may do the basshorns next.. it is just hard to motivate to start a new woodworking project in winter... but I dearly miss having horns from 200 down...
these are all steps I have traveled before, but each time you start over, you learn something new... but it is hard when you are in the construction stages... I can hear the differing dynamic abilities of the low mid horn and the bass cabinet... sigh... and I *know* how much better line level crossovers are.. every time they astound me...
oh.. and I just found out the 505 has a resonance of 80 Hz... hmmm....
Peace,
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