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In the Forum: Horn-Loaded Speakers
In the Thread: Eventually - a reasonable midbass horn from GOTO
Post Subject: More on GOTO / Experience Music horns...Posted by Jeffrey Jackson on: 11/21/2007
Hello again, Romy.. let me see if I can clear some of this up....
first, you are indeed correct on your horn thoughts.. but some clarification is in order...
Ming Su is the importer of GOTO to the USA... Goto Japan only ships horns from flare frequency 150 and up... if you want something bigger, they offer assistance and drivers...
they do this for the very reasons you state.. such a horn really has to be considered in the context of the room and with the whole of music reproduction in mind... large horns require much thought... Ming would like to provide this custom basshorn service to his customers in the US market.. Goto Japan has nothing to do with this...
Ming is relatively new to this art of horn building... he has heard quite a few Japanese systems.. he has heard many traits that he liked.. afer living with compression driver top end and GOTO 15's in Onkens to cover 300 and down, he really wanted to try horn loading lower... I have built quite a few such horns and some friends connected us...
he has listened to Goto's advice quite a bit.. they have very strong thoughts on how to do things... some you will find humorous, others you will agree with... they beleive that electronics don't really matter.. the driver is the primary importance above all others... to them, it is silly to buy expensive electronics if you do not have double drivers on all your horns.. (I do not believe in this, at all) .. they also do not believe in time alignment... I have heard the amazing transformation that time alignment brings, both with digital correction and with physical alignment... Goto says the drivers can just go anywhere.. their philosophy is that a low distortion loudspeaker is the most important thing...
double drivers... I am with you on double drivers... I understand that it shortens a horn.. to me, that is usually a bad direction.. length helps with loading.. especially in the lower frequencies... (at high frequencies I tend to like short horns, subjectively)... I also find that double drivers in the mids and up confuse things a bit.. a touch "blurry"... but I must say that I know two people who liked double drivers in the 300 to 1500 range better than single.. do note that both have *large* rooms... also note that Ming'shorn has adequate length at over 8' for a 60Hz flare...
so Ming's system... I think he will get "there"... he has several options.. locate the 300 cycle horns in the mouth of the midbass horns... flip the midbass horns sideways to the floor and then position the midhorns above the midbass horns... third, place the midbass horns sideways along the ceiling and use low basshorns below... 300 cycle horns could go into the low bass horn mouth...
as they are, if the 15's in boxes go below the dual compression drivers, at least those two would be very close in alignment...
so what have we skipped.... the rear chamber and reactance annulling... yes, I know this subject very well... it makes a very audible difference... and deserves our attention... Bell Labs actually published a formula for source impedance with regards to horn impedance.. it was quite enlightening.. they used very high output impedance amps with their horns... and, yes, they had *giant* aluminum diapragmed compression driven bass horns... interesting, no?
hyperbolic is just a slower starting exponential.. it is what goto favors.. you can cross closer to the flare frequency with this expansion.. it loads the driver very well down low... as an example, my goto 150 horn with single SG505 is 50 inches long! this is well over a half wavelength at 150Hz...
the throat of Ming's horn is two times 100 mm diameter openings, I believe... I did not build the dual throat adaptor.... the drivers are quite impressive in scale.. the pictures make them seem smaller than life... but I do wish we could have the rear chambers modified for the task, as you pointed out... Goto, as far as I know, does not do this for any of their horns... for each driver they sell a few different size horns.. and no changes to teh driver... :^(
cost for such a project varies widely... this one required hiring help as the individual pieces were too large to carry with one person... in standard black finish (actually three coats of stain and paint) it would be about US$15k... this includes delivery and setup in the continental US... moving to even a 70 Hz horn would drop the price significantly... adding veneers would quickly raise the cost...
I am working on a LONG ceiling mounted straight horn for a Cogent large driver.. still planning stages only, but I cannot wait to hear it...
I would recommend this construction method to any DIY'ers, but just be forewarned that it takes *lots* of time to build in this method... I used up nearly 40 sheets of 4' x 8' plywood in this construction... so just moving the panels is work...
hmmm... and Ming's email to you... I think you guys had a miscommunication... Ming will not be using any cone drivers on this horn... if we build a horn for the cone drivers, then it will be for use from 70 down and properly tuned...
anything else I missed?
keep pursuing the sound!
Peace,
Me
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