Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

Alec Model 19 Custom Built-In Cabinet Plans
Alec Model 19 Custom Built-In Cabinet Plans
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 21st July 2019, 12:45 AM   #1
Aeroaudio is offline Aeroaudio  United States
diyAudio Member
 
Join Date: Apr 2019
Location: North Texas
Default Alec Model 19 Custom Built-In Cabinet Plans

This is my first post on DIY Audio, although I have been following many of the forum posts on speaker projects for over three years. It seems that whenever I do a Google search regarding speaker design, DIY Audio Forum posts are at the top of the list generated (of real information).

Five years ago my wife and I purchased a very unique modern design home that was built in 1967. The house was equipped with every possible high end feature available, including close circuit TV, electric curtains, solenoid controlled lighting from a central panels (one panel built into the master bedroom night stand controls every light in the house), stereo speakers in the ceiling of every room but one (Frazier of Dallas 1.5 cuft cabinet speakers with 8" Altec woofers and Foster horn tweeters), Sony RTR player, Dual 1009SK turntable, and a Fisher tube receiver (Fisher unit long gone). The one room without Frazier ceiling speakers is the "Media Room", which has 15" Wolverine LT15 triaxial speakers built into a walnut wall media cabinet . See attached photos.

I spent last year (with the guidance and help of a great guy Glen) sorting out the Frazier speakers, rebuilding the original drivers, building new crossovers, and tuning the cabinets. if you are interested in more information, I posted the restoration process at Vintage 1967 Built In High End Home Hi Fi | Audiokarma Home Audio Stereo Discussion Forums

This year I am attacking the Media Room system. Originally I planned to reuse the Wolverines and tune the cabinets properly. The builders of the media center cabinets were fine wood working craftsmen, but lousy speaker cabinet designers. But I am getting older, and If I am going to invest my scarce time in a project, I want it to be the best I can afford. So the Wolverines are destined for eBay.

Over the past year I have spent many hours sketching different speaker configurations for the media center. Most of them utilized the Altec 604 coaxial as the basis. I started off trying to keep some of the electronics in the two side areas behind the hinge screens. But I came to the conclusion that it was best to make use of all the volume on the sides, and relocate all electronics to the area above the TV. This area (originally for the TV) is nice and deep, ventilated, and can be totally hidden by two doors that slide out from either side to disappear when open. This also gives me the freedom to change electronics more easily should I want to play with different amps, preamps or sources.

I thought I would try to fit an MTL configurationinto the space available. While I could just about make it fit, the compromises I needed to make did not guarantee success. While volume was adequate, port location and cross-sectional area were not optimal. Going back to a conventional bass reflex design was the best option. But I was hoping to get deeper base in the conventional 604 would get in a bass reflex cabinet. Also the 604 tweeter height was a little bit taller than my seating height on the couch. Without electronics in the area I could mounted lower, but the screens on the doors have woodframe bars that would block the tweeter with the door closed. So a complete re-think was required. FYI Wife is very understanding, but one house rule is that with the door closed the cabinets must look the same. I also do not want to butcher these beautiful walnut cabinets.

I had been reading a lot about the Altec Model 19, and had heard only good things. So using the dimensioned drawings I found of the Model 19 cabinet my plan changed course. Using the modern GPA 416-8B in a 8.8 cuft bass reflex cabinet gets me a respectable 25 Hz bottom end (according to GPA). While installing the the Altec 811-B horn below the 416 can get me the tweeter height closer to optimal. Reading the Model 19 manual I even discovered instructions on how to position the cabinets upside down for studio use. As a final bonus, the drivers clear almost all the screen obstructions.

I was looking for some sign from the audio gods to tell me if this was the best direction to go with the cabinet design. The sign came from an ad on eBay forAltec 811 horns for sale in perfect originalcondition, and just 15 minutes drive from my house. Within one hour of seeing the ad I purchased the horns and brought them home.They were just as described perfect condition and they only cost me $90. In seeing these huge aluminum monstrosities my wife commented "Well if you don't use them for the speakers, I can make them into some very interesting flower vases¯.

Over the past year I have been putting aside funds for this project. Last week I communicated with Bill at GPA, and told him I would be putting in an order for all the parts I needed within the next few weeks. Oklahoma City is just a 3 hour drive North of me. So I can pick up all the components and save both shipping and worry.

Now I need some input and comments from the DIY Audio community. Please take a look at the attached plans (low resolution in photo, high res in PDF) and let me know what you think. I am especially interested in any comments regarding the port location and size, placement and type dampening material to use, and any thoughts concerning cabinet rigidity. Note that I have isolated the HF horn completely from the LF volume. I have also moved the LF and HF drivers closer together. Depth of driver mounting is identical to the Model 19.

The top,bottom, and sides of the cabinets are 1.50" furniture grade plywood (no voids). The front and back of the cabinets will be 0.75"¯ furniture grade plywood with0.75" MDF bonded to it. I am thinking that with this thickness there is no need for any internal bracing. But I need some reassurance.

All comments and suggestions welcome.

Thanks in advance.
Attached Images
File Type: jpg IMG_2128.jpg (602.3 KB, 328 views)
File Type: jpg IMG_2129.jpg (567.2 KB, 328 views)
File Type: jpg IMG_0775.jpg (650.0 KB, 321 views)
File Type: png IMG_1433.PNG (894.9 KB, 314 views)
File Type: png IMG_1437.PNG (223.0 KB, 307 views)
Attached Files
File Type: pdf Vinewood Cabinet Mod to Model 19s 071219.pdf (595.9 KB, 19 views)

Last edited by Aeroaudio; 21st July 2019 at 04:43 PM. Reason: Cut and paste resulted in punctuation going wonky.
  Reply With Quote
Old 21st July 2019, 04:50 PM   #2
Aeroaudio is offline Aeroaudio  United States
diyAudio Member
 
Join Date: Apr 2019
Location: North Texas
Default Low Resolution Photo of Cabinet Plans

Low Resolution Photo of Cabinet Plans attached.
Attached Images
File Type: png IMG_2896.PNG (283.7 KB, 303 views)
  Reply With Quote
Old 21st July 2019, 06:26 PM   #3
Dilbert is offline Dilbert  Canada
diyAudio Member
 
Join Date: Feb 2009
Location: Toronto, Canada
A very cool house and project. I can’t speak for the GPA 802’s shown on your drawing, but I am using their 902-8A with fantastic results in my 846B Valencia’s. Highly recommended!
  Reply With Quote
Old 22nd July 2019, 12:18 AM   #4
EarlK is offline EarlK  Canada
diyAudio Member
 
Join Date: Mar 2006
Location: Toronto (GTA), Ontario
Nice! project Aeroaudio.

Click the image to open in full size.

I see two different sets of furniture here ?

Click the image to open in full size.

Click the image to open in full size.

Personally, I'd hide the big ducted port ( or just make it a simple slot port located at the top of the baffle board ). I'd also hide the crossover face/knobs ( within a drawer maybe ?? ).

Aesthetically, I'd prefer to see nothing but an expanse of nice wood grain above the woofer ( but that's just my opinion as if it were my stuff ).

I like the horn height and woofer layout / that should work well enough for you ( & the shortish throw distance to the couch and glass ).

I'd also advise to the making of a plain mockup ( removable ) plywood baffle-board where you can experiment with different box tunings ( and maybe port locations ).

It's not a slam-dunk that you're going to get the bass response that you expect and want due to this media center effectively being located ( acoustically ) in a much larger room than its immediate location.

Locating the woofer almost 1/2 way between floor and ceiling will trigger some rarely encountered room modes ( exactly which ones, I can't really tell you ).

You'll want to get a test mic and learn to use something like REW ( to help identify and then tame your somewhat hostile room acoustics > from all the glass & polished marble/terrazzo ).


Last edited by EarlK; 22nd July 2019 at 12:22 AM.
  Reply With Quote
Old 22nd July 2019, 03:19 AM   #5
Aeroaudio is offline Aeroaudio  United States
diyAudio Member
 
Join Date: Apr 2019
Location: North Texas
Thanks for the input EarlK.

The circular port was not my first choice in configuration. Original layouts used a slotted port. But unlike typical speaker cabinet construction, the installation allows no access to the back or sides of the speakers. Everything needs to be accessible from the front. To attach the baffle board I will be using lag screws that will be accessible by reaching through the speaker hole and the port hole. I can get my arm through a 6” diameter port hole, but I cannot reach through a 2.5” slot. So the round port lets me reach the upper bolts.

For initial trials I will use the plastic Precision Port. But it will be replaced later with a turned wood port.

The listening position is 12’ from the speakers. The floor in front of the speakers had a heavy shag rug, and the window facing the speakers are covered with heavy drapes. This should help dampen the hard reflective surfaces. Also the media room is not too large, about 15’ X 15’.

A series of trial baffle boards is a good idea. Will play with different configurations. Will also look at different locations for the L pads.

FYI. Some of my posted photos are from the prior owners furniture.
  Reply With Quote
Old 22nd July 2019, 04:03 PM   #6
Aeroaudio is offline Aeroaudio  United States
diyAudio Member
 
Join Date: Apr 2019
Location: North Texas
I hadn’t intended to discuss the room acoustics in this post. Other than wall and floor surface treatments there are no changes acceptable. As Earl points out, the media center is not connected to the side walls, but is open floor to ceiling on both sides by four feet. Behind the media center is a large open floor plan with the nearest wall over 28 feet away. It would be interesting to know what affects this will have on room acoustics. But there is really nothing I can do to change this room configuration.

The room ceiling is 8 ft and the woofer will be 49” above the floor. So half way up as Earl states. But I have seen many 604 duplex cabinet designs with the driver located close to this height. So is this a concern?
  Reply With Quote
Old 22nd July 2019, 07:14 PM   #7
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Greets!

Got plenty to say and not much time ATM, so may be awhile and/or in 'snippits' such as your 'game' changing floor/ceiling eigenmodes causing a huge/deep fundamental null that theoretically will 'suck the life' out of any speaker output centered at ~565 ft/8 = ~70-71 Hz, which of course is where the vocals, most music's 'foundation' is and no practical amount of extra power will overcome it, though not for lack of lots of folks over time trying and have the burned up driver VCs and/or amps to prove it.

Wouldn't hurt to join the AUB also if not already since there's lots of M19 centric folks there: Altec User's Board

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 22nd July 2019, 07:26 PM   #8
GM is offline GM  United States
diyAudio Member
 
GM's Avatar
 
Join Date: Jun 2003
Location: Chamblee, Ga.
Quote:
Originally Posted by Aeroaudio View Post
I hadn’t intended to discuss the room acoustics in this post.

But I have seen many 604 duplex cabinet designs with the driver located close to this height. So is this a concern?
As I just noted, the room dominates, so the driving force behind any speaker design suggestions [at least on my part], so can't have too much detailed info on it.

If with 8 ft. ceilings, you may rest assured that there's a notch in the 604's response in the 70-80 Hz BW, one of several worst places for a notch to be WRT a potentially above average performance IME, but we all hear the same, yet not so much, so as always YMMV.

GM
__________________
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
  Reply With Quote
Old 22nd July 2019, 11:26 PM   #9
Aeroaudio is offline Aeroaudio  United States
diyAudio Member
 
Join Date: Apr 2019
Location: North Texas
Quote:
Originally Posted by GM View Post
As I just noted, the room dominates, so the driving force behind any speaker design suggestions [at least on my part], so can't have too much detailed info on it.

If with 8 ft. ceilings, you may rest assured that there's a notch in the 604's response in the 70-80 Hz BW, one of several worst places for a notch to be WRT a potentially above average performance IME, but we all hear the same, yet not so much, so as always YMMV.

GM
GM, I was hoping you would respond to my post. Regarding your request for more detailed info, attached is a photo of the house's floor plan blueprint showing the media room dimensions, and the living room behind the media center wall.

The woofer I plan to be using is the Model 19's 416-8B. I was just referring to the driver height of some cabinet designs using the 604. The only other knob I have available to turn is the baffle board inclination. I can incline it down a few degrees if it can help in any way.
Attached Images
File Type: jpg Media Room Floor Plan.jpg (266.0 KB, 44 views)
  Reply With Quote
Old 25th July 2019, 02:34 AM   #10
Aeroaudio is offline Aeroaudio  United States
diyAudio Member
 
Join Date: Apr 2019
Location: North Texas
GM. I will post my request for information on cabinet design on the Altec site as you suggest. I already posted on the GPA Altec Facebook site. Still, if you have any thoughts on port configuration and position it would e appreciated.
  Reply With Quote

Reply


Alec Model 19 Custom Built-In Cabinet PlansHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Mouse over image to zoom Custom-built-audiophile-quality-speakers Custom-built-audi djn Swap Meet 7 21st August 2016 05:49 PM
Custom Built PA subwoofer shaggerz Subwoofers 18 30th July 2010 01:49 PM
My Custom Built sub!! marcmdm2005 Subwoofers 0 5th June 2010 06:59 PM


New To Site? Need Help?

All times are GMT. The time now is 12:21 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki