Page 1 of 2 12 LastLast
Results 1 to 10 of 11

Thread: So here's my thinking????

  1. #1
    Senior Hostboard Member LOUDER's Avatar
    Join Date
    November 16th, 2010
    Posts
    193
    Follows
    0
    Following
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    16 Post(s)

    So here's my thinking????

    Since everybody"s running a sub nowday"s, how small can you make a Model 19 ? I have enough 811's and 421-8h's to do a 7.1. 811 width plus a inch and a half, 811 height plus 16.125 plus a inch and a half, plus 811plus 808 plus two inches plus 3/4's. Does that get me to 80 hz ? The 421 will be reconed as gpa 515 lf's. The Altec 1233's are the closest that I have come across. Please everybody chime in so we know your not dead from the covid-19.

  2. #2
    Junior Hostboard Member horndawg's Avatar
    Join Date
    April 4th, 2006
    Posts
    23
    Follows
    0
    Following
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    0 Post(s)

    Re: So here's my thinking????

    There's this huge thread titled "beyond the Ariel" over at diyaudio where the OP, Lynn Olson, came to a 'sort of' conclusion that a large Hi-eff two way a la Altec Iconic would be his preferred configuration. It took years to get there but that's beside the point. He never managed to built a speaker, but his buddy and partner in crime Gary Dahl managed to do so.

    The components he settled on after some trial are the GPA-416B Alnico and the Radian 745PBNeoBE on an Azura AH-425 horn. This is a round expo horn similar to the 811 in dimensions and low frequency cut-off. He uses the 416 in a 3 cu. ft. sealed enclosure that gets down to around 70 Hz and has a sub assisting bellow that point. I believe it's an AE TD15H with passive radiators for the sub.

    So, to answer your question, it's doable and if you research the aforementioned thread you will find more details i.e. crossover schematics, enclosure dimensions etc.

    PS

    BTW Gary Dahl also tried the GPA 515C Alnico and preferred the 416 in this application

    Here's a link to his description of the system

    Beyond the Ariel - Page 1114 - diyAudio
    Last edited by horndawg; October 29th, 2020 at 09:44 PM.

  3. #3
    Senior Hostboard Member GM's Avatar
    Join Date
    December 26th, 2002
    Location
    Chamblee, Ga.
    Posts
    4,930
    Follows
    0
    Following
    0
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    43 Post(s)

    Re: So here's my thinking????

    As a general rule, the horn/driver sizes will dictate a minimum sealed cab's net volume [Vb] and the driver's specs for vented, so for vented it's ~63.48 L/2.242 ft^3 net tuned to ~52.1 Hz based on Altec's published specs, though remember my [2] NIB measured somewhat differently once warmed up a bit.


    Hornresp [HR] 'says' both types are Xmax limited to ~30 W with sealed ~105 dB/m/2pi/80 Hz and the vented at ~110 dB/m/2pi/80 Hz; both based on typical SS amp/receiver and 0.5 ohm for XO, wiring losses. Overdrive them 1.5x Xmax, add ~5 dB. ~52.1 Hz Fb = 3" dia. x 0.75" vent.


    Anyway, just for reference, I didn't try to work out what the real world minimum [Vb] might be, better to just build and post internal dims and either run them sealed or let us know and will dial in the vent.


    In short, the 421-8H meets your basic requirements.


    For reconed to 515 LF, will need Bill's build T/S specs.


    GM

    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  4. #4
    Senior Hostboard Member LOUDER's Avatar
    Join Date
    November 16th, 2010
    Posts
    193
    Follows
    0
    Following
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    16 Post(s)

    Re: So here's my thinking????

    Horndawg and GM thanks for chiming in. At least we know the covid didn't get you. I'm going to build a prototype this weekend. I'll let you know dimensions and first listening impressions next week. The GPA 515 lf is very similar to a 421 including the magnet size. the only real difference being usable x-max. GPA 515lf x-max .20, re 6.7 vd 23.,fs 27.4 vas 16.6 ref eff 6.7 qts .255 qms 11.63 qes .261 flux density 14,750. Oh and I like the preliminary 3" x .75 vent hole. One buy three in the back at the top so I can carry the around easily.

  5. #5
    Senior Hostboard Member
    So here's my thinking????


    Old Guy's Avatar
    Join Date
    June 23rd, 2003
    Posts
    6,330
    Follows
    0
    Following
    0
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    56 Post(s)

    Re: So here's my thinking????

    Quote Originally Posted by LOUDER View Post
    Horndawg and GM thanks for chiming in. At least we know the covid didn't get you. I'm going to build a prototype this weekend. I'll let you know dimensions and first listening impressions next week. The GPA 515 lf is very similar to a 421 including the magnet size. the only real difference being usable x-max. GPA 515lf x-max .20, re 6.7 vd 23.,fs 27.4 vas 16.6 ref eff 6.7 qts .255 qms 11.63 qes .261 flux density 14,750. Oh and I like the preliminary 3" x .75 vent hole. One buy three in the back at the top so I can carry the around easily.
    The 421 won't be a 515 no matter what you do. The 421's top plate is different, thicker if I recall. You won't know what you have until you test.

    Bill may have done enough of this to get you an approximation. But even with magnets being close it will still be different. I would likely go with the 421 kit, with a paper or felt dome instead of the aluminum. It should get you to where you need.
    Your neighbors called. They like your music.

  6. #6
    Senior Hostboard Member LOUDER's Avatar
    Join Date
    November 16th, 2010
    Posts
    193
    Follows
    0
    Following
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    16 Post(s)

    Re: So here's my thinking????

    OG, as far as I can remember, all Altec speakers are a 1/2 top plate. The pro models and 515's. (actually .47. I don't know why this is. After machining and plating ? Is this the number that comes up?) I measured some of the speakers in my stock this morning, and they all came up with this thickness. Just didn't have time to post this morning. What was really weird , is that the 515's that I have, all looked bigger than 1/2". But, when I measured them I got the same 1/2". ( Optical illusion ? Must be, big ol' chunk of cast iron hanging off the back.) Anyway,s It wasn't Uncle Willy's call but mine. Didn't even ask him. The last 515 lf kit's he sent me had the orange spider instead of the black one and he's now using latex to seal the surround instead of the c.p. moyen goop we're all used to. I'll update you when I get the new kits. ( Still haven't pulled the trigger on the 299's.

  7. #7
    Senior Hostboard Member
    So here's my thinking????


    Old Guy's Avatar
    Join Date
    June 23rd, 2003
    Posts
    6,330
    Follows
    0
    Following
    0
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    56 Post(s)

    Re: So here's my thinking????

    Quote Originally Posted by LOUDER View Post
    OG, as far as I can remember, all Altec speakers are a 1/2 top plate. The pro models and 515's. (actually .47. I don't know why this is. After machining and plating ? Is this the number that comes up?) I measured some of the speakers in my stock this morning, and they all came up with this thickness. Just didn't have time to post this morning. What was really weird , is that the 515's that I have, all looked bigger than 1/2". But, when I measured them I got the same 1/2". ( Optical illusion ? Must be, big ol' chunk of cast iron hanging off the back.) Anyway,s It wasn't Uncle Willy's call but mine. Didn't even ask him. The last 515 lf kit's he sent me had the orange spider instead of the black one and he's now using latex to seal the surround instead of the c.p. moyen goop we're all used to. I'll update you when I get the new kits. ( Still haven't pulled the trigger on the 299's.
    I remember it being different. I also had a conversation with Jim- forgive the senior moment I am drawing a blank on his last name, but he was a much bigger player at Altec and that was his feeling also. I don't have one to measure right now.
    Your neighbors called. They like your music.

  8. #8
    Senior Hostboard Member LOUDER's Avatar
    Join Date
    November 16th, 2010
    Posts
    193
    Follows
    0
    Following
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    16 Post(s)

    Re: So here's my thinking????

    OG, as far as I can remember, all Altec speakers are a 1/2 top plate. The pro models and 515's. (actually .47. I don't know why this is. After machining and plating ? Is this the number that comes up?) I measured some of the speakers in my stock this morning, and they all came up with this thickness. Just didn't have time to post this morning. What was really weird , is that the 515's that I have, all looked bigger than 1/2". But, when I measured them I got the same 1/2". ( Optical illusion ? Must be, big ol' chunk of cast iron hanging off the back.) Anyway,s It wasn't Uncle Willy's call but mine. Didn't even ask him. The last 515 lf kit's he sent me had the orange spider instead of the black one and he's now using latex to seal the surround instead of the c.p. moyen goop we're all used to. I'll update you when I get the new kits. ( Still haven't pulled the trigger on the 299's.

  9. #9
    Senior Hostboard Member GM's Avatar
    Join Date
    December 26th, 2002
    Location
    Chamblee, Ga.
    Posts
    4,930
    Follows
    0
    Following
    0
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    43 Post(s)

    Re: So here's my thinking????

    Quote Originally Posted by LOUDER View Post
    Horndawg and GM thanks for chiming in. At least we know the covid didn't get you. I like the preliminary 3" x .75 vent hole. One buy three in the back at the top so I can carry the around easily.
    You're welcome!

    So far, though AFAIK I'm immune to it, but the related stuff is starting to get on my last nerve.

    Uh, I posted 3" dia. = 3^2*pi/4 = ~7.07"^2/3.00"^2 = ~2.36x larger, so make it a 3" x ~2-5/16"-3/8" or some other ratio vent as required.

    GM
    Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.

  10. #10
    Senior Hostboard Member LOUDER's Avatar
    Join Date
    November 16th, 2010
    Posts
    193
    Follows
    0
    Following
    0
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quoted
    16 Post(s)

    Re: So here's my thinking????

    GM, I didn't mean to get on your last nerve. I'm just hackin' and a whack'in tryin' to build some cabinet's. Here's my final dimensions. 20" wide, 26 1/2 high. and 16 3/4 deep. accounting for the 2" offset for the 811's, minus the horn volume and speaker volume, I ended up with 3.54 cubic feet. A 930 cabinet is 3.95 cubic feat. And according to the AN # 5 notes this puts me a variable range using a 2 x 10 port opening depending on which speaker recone kit I go with. It's still going to be a nice handle hole to carry it around with. PM me if you need a set of 811's to go with those 421's you are still rotating in the closet.

Page 1 of 2 12 LastLast

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
This forum has been viewed: 20820612 times.