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  »  New  A right midbass solution for Altec 515G...  Its even possible to make my midbass......  Horn-Loaded Speakers Forum     21  93933  05-06-2007
  »  New  Eventually - a reasonable midbass horn from GOTO..  Clever DIY going on where?...  Horn-Loaded Speakers Forum     97  604903  11-19-2007
  »  New  60hz, GPA-515-8ghp horn.....  60hz horn...  Horn-Loaded Speakers Forum     32  159603  07-01-2008
  »  New  ... again on GOTO Unit drivers.....  GOTO get time-aligned help.... Eventualy!!!...  Horn-Loaded Speakers Forum     107  607058  08-16-2008
  »  New  The tapped horns: cons, pros and Sound..  The new use of Trapped Horn idea....  Horn-Loaded Speakers Forum     54  363876  04-23-2009
  »  New  Midbass Horns and Real Estate...  ALE Loudspeakers....  Horn-Loaded Speakers Forum     246  1140153  07-26-2009
  »  New  Macondo’s Midbass Project – the grown up time...  A new house --- again...  Horn-Loaded Speakers Forum     454  1471489  05-20-2010
11-03-2008 Post does not mapped to Knowledge Tree
Kcct82
Beijing, China
Posts 23
Joined on 09-08-2008

Post #: 1
Post ID: 8695
Reply to: 8695
8" Goto Woofer for 60Hz Horn
fiogf49gjkf0d

Hey Romy,

Goto makes 12" and 15" woofers at 100db. I recently found out they make a small two way system using an 8" woofer. The 8 incher's range is 55hz-8000hz so I'm thinking it might be a good candidate for use with 60Hz horns. Looking at Goto's 12" and 15" woofers, they seem to be paper cones and "altec looking". Too bad the website didn't state the efficiency of the 8" driver but I'll try to find out... if it's a 100db like their 12"/15" drivers then it might be something worth looking into... heck I'll be impressed even at 98db...

Keith

11-03-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,249
Joined on 05-28-2004

Post #: 2
Post ID: 8699
Reply to: 8695
GOTO - no one knows anything….
fiogf49gjkf0d

 Kcct82 wrote:

Hey Romy,

Goto makes 12" and 15" woofers at 100db. I recently found out they make a small two way system using an 8" woofer. The 8 incher's range is 55hz-8000hz so I'm thinking it might be a good candidate for use with 60Hz horns. Looking at Goto's 12" and 15" woofers, they seem to be paper cones and "altec looking". Too bad the website didn't state the efficiency of the 8" driver but I'll try to find out... if it's a 100db like their 12"/15" drivers then it might be something worth looking into... heck I'll be impressed even at 98db...

Keith, it is hard to say. I think you need to talk with somebody why use GOTO drivers. I do not know what contrary you are in but you might find some collaborators on line. How accurate and objective would be their comments is another subject – you decide foe yourself.

Generally you do the very same mistakes as anybody else does – you name the rate of horn but you do not specify what the throat size. There are 3 parameters that are critical in horns: moth size (or frequency), throat size and profile type. So, 60Hz horn with 8” throat and 60Hz horn with 18” throat are different horns as you understand.  Usually if to use 8" driver then we are talking about 7” horn – it looks very good. How the driver will work in there – who knows? I would pay attention in case of 8" driver in it’s excursion.  Pressure is excursion + surface. Less surface = more excursion. Mores excursion with lower resonance frequency and consequential softer sustention = less disable driver for horn. (You would need for horn hard-suspended driver with fewer excursions). Evan if the driver has a long excursion then how much of it in homogeneously saturated gap? (The underhand paranoia…) Well, be advised that it all might have no relation to sound. Be also advised that smaller throat = more LF equalization but this rule is not infinite. Lowering throat smaller and smaller we eventually get very nasty sound, particularly with slow opening horns. Where is the golden rule of throat/mouth ratio? I do not know. I think with each driver and each construction techniques it might wary.

Somebody at this site was trying to equate the throat/mouth ratio for MF channel and to apply it to upperbass horns.  It “sounds” like right thing to do but I do not think that the “rule” will be preserved in midbass world. So there is no definitive answers, at least that I know.  If I go for my 55Hz horn I would go for 15” driver with 10-12” throat  but I think that I would it ONLY BECOSE I do not know any good  8” driver. Your GOTO might be such a “better” driver but it might not be. Hey might do good 15" woofers and they make “cheap” 8” versions for “easy” systems. The people who use GOTO would know it. The best bet would be if they send you 8’, 12" and 15” drivers and you would compare them with TAD, Altec, JBL, Vitavox, Klangfilm… but if you do then… you would not post your questions on internet….

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-23-2008 Post does not mapped to Knowledge Tree
Kcct82
Beijing, China
Posts 23
Joined on 09-08-2008

Post #: 3
Post ID: 8938
Reply to: 8699
A little more info on the driver
fiogf49gjkf0d

Thanks Romy, your comment above cleared some of the questions I had regarding 50/60hz midbass horns.

I found some info on the driver after digging through Japanese sites. I don't know if these info will help interpret wither the woofer will be good for MB horn but perhaps you can see something interesting from these specs... thanks.

GOTO SG-20WR:
20cm (8 inch)
20W
8 ohms
96 db/w/m
100,000 Maxwell
8,000 Gauss
55hz (Qo 0.25)



11-23-2008 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,249
Joined on 05-28-2004

Post #: 4
Post ID: 8939
Reply to: 8938
The last 5-10Hz... and the driver.
fiogf49gjkf0d
Keith,

You would never know from the data how those upperbass driver will behave in horns. The 55Hz of air resonance (if it is true number that always not the case) is a good number for 60-70Hz horn. I really would like to know the max amount of mm that the driver runs away and the length of the gap. Knowing excursion, magnetic density (8,000 Gauss is on low side), geometry and sensitivity it is possible to make a rudimental assessment, which still might not be related to actual sound. I am a little concern that the driver has just 96dB. It might be a sign that GOTO went economical on magnet – that would be bad. Or it might be a sign that GOTO wanted to keep the bottom knee of this driver to be “soft” – that is very good sign.

If you are looking for 50/60Hz midbass horns then I would say that this diver might be a bit too stiff. GOTO has SG-30WR driver that has 10Hz lover resonance frequency and it might be a better chose if you insist to stay with GOTO. The last this you would like to have is to build 60Hz midbass horn and to learn that your driver (not the horn) eat the last 5-10Hz. Do not forget that in your 5-10Hz will be the 70% of your horn’s cost…

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
11-08-2009 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,249
Joined on 05-28-2004

Post #: 5
Post ID: 12178
Reply to: 8938
The KCCT82’s midbass horn.
fiogf49gjkf0d

 Kcct82 wrote:
Thanks Romy, your comment above cleared some of the questions I had regarding 50/60hz midbass horns.

I found some info on the driver after digging through Japanese sites. I don't know if these info will help interpret wither the woofer will be good for MB horn but perhaps you can see something interesting from these specs... thanks.

GOTO SG-20WR:
20cm (8 inch)
20W
8 ohms
96 db/w/m
100,000 Maxwell
8,000 Gauss
55hz (Qo 0.25)

Got today from web pictures of the Keith midbass horn.  So, it is GOTO SG-20WR loaded to 50/60hz midbass exponential like ½ size, interesting…. The picture with a person in front dives an idea about the dimensions but it would  be nice to know from Keith the mouth size, the length, the throat size, and the mass of the horn.

Formally the KCCT82’s installation was mentioned in here:

http://www.goodsoundclub.com/Forums/ShowPost.aspx?postID=10333

KCCT82_Midbass_1.jpg


KCCT82_Midbass_2.jpg


KCCT82_Midbass_3.jpg

The Cat


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
04-08-2011 Post does not mapped to Knowledge Tree
Kcct82
Beijing, China
Posts 23
Joined on 09-08-2008

Post #: 6
Post ID: 15954
Reply to: 12178
It's not a Goto 8in driver
fiogf49gjkf0d
Hi Romy, I ended up using a TAD 1101h 11 inch driver, 97db, 38fs, and is what I believe a stronger cone than the Goto 8 inch. The DIY mid bass horn is a 1/2 space 53hz hyperbolic horn with 5in x 5in square throat. Length is about 8'6", height of mouth is 3'4", and width is 5'4". I'm still learning how to implement it but can confirm that back chamber is a must. For 2 years I left the back open and could never get a center image in the lows along with many other problems. It is much better now and next is to optimize the chamber size. Best, Keith
Page 1 of 1 (6 items) Select Pages: 
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  A right midbass solution for Altec 515G...  Its even possible to make my midbass......  Horn-Loaded Speakers Forum     21  93933  05-06-2007
  »  New  Eventually - a reasonable midbass horn from GOTO..  Clever DIY going on where?...  Horn-Loaded Speakers Forum     97  604903  11-19-2007
  »  New  60hz, GPA-515-8ghp horn.....  60hz horn...  Horn-Loaded Speakers Forum     32  159603  07-01-2008
  »  New  ... again on GOTO Unit drivers.....  GOTO get time-aligned help.... Eventualy!!!...  Horn-Loaded Speakers Forum     107  607058  08-16-2008
  »  New  The tapped horns: cons, pros and Sound..  The new use of Trapped Horn idea....  Horn-Loaded Speakers Forum     54  363876  04-23-2009
  »  New  Midbass Horns and Real Estate...  ALE Loudspeakers....  Horn-Loaded Speakers Forum     246  1140153  07-26-2009
  »  New  Macondo’s Midbass Project – the grown up time...  A new house --- again...  Horn-Loaded Speakers Forum     454  1471489  05-20-2010
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