Altec 2 Way Build ala JELabs - 802/32/414

marantzfan

Administrator
Staff member
The tube looks to be recessed 3/8” into the front baffle. I expanded the drawing so the 3/4 baffle was 1/4“ on my ruler and came up with the 4.5”. I can’t imagine 1/4” making much of a difference. @marantzfan can you stick a tape measurer in your tube and measure the length?
Looks like I’m at about 5 1/4” on the tube. Recessed the tubes 1/2” on 3/4” BB baffle, so about 5 1/2” total.
 
Does anyone have a link that explains the different variations of the 414? For example, what’s the difference between 16b and 16c? Thanks
 
That was my post. It is based on personal experience, drivers I have seen in person or online, and from Altec catalogs. I’m also told that Altec because increasingly less organized in the 1970’s and documentation because a bit more difficult to find.

There is a deep hobbyist knowledge base on Altec products, but it is spread throughout the Internet and is difficult to bring together. I wish that Audioasylum were a bit more modern in its platform since it has posts dating back further than almost anyone else. Diyaudio has an incredible depth of information but good luck finding it.

There are a lot of competing audiophile forums. A number go as far as to ban the mention of any other forum, let alone linking to another site. Hifihaven is great in that it allows exchange of ideas from multiple sites. It would benefit us all if some of us began to curate some of our favorite links to other Altec-specific threads or links here at the Haven.
 

Fran604g

Just Call Me Junior
That was my post. It is based on personal experience, drivers I have seen in person or online, and from Altec catalogs. I’m also told that Altec because increasingly less organized in the 1970’s and documentation because a bit more difficult to find.

There is a deep hobbyist knowledge base on Altec products, but it is spread throughout the Internet and is difficult to bring together. I wish that Audioasylum were a bit more modern in its platform since it has posts dating back further than almost anyone else. Diyaudio has an incredible depth of information but good luck finding it.

There are a lot of competing audiophile forums. A number go as far as to ban the mention of any other forum, let alone linking to another site. Hifihaven is great in that it allows exchange of ideas from multiple sites. It would benefit us all if some of us began to curate some of our favorite links to other Altec-specific threads or links here at the Haven.
In that spirit:
Although I haven't frequented Todd White's Altec User's Board forum for a few years, is it still relevant to our efforts? I found it to have quite a lot of info and insight from its members - at least within the realm of 604 drivers.

Cheers,
Fran
 
It is interesting to look at the response of the 614 vs. 9849 with a 414-8C as illustrated In this post. Note that I erroneously provided him with a port length of 6”, not 5.5”. The tuning frequency should be 39hz with the 5.5 inch port.

The 9849 was designed as a control room monitor intended to be mounted “upside down” in the soffit. The 32A/B horn has a 15 degree (IIRC - I’m sure @je2a3 can provide the correct number) downward lobe when mounted this way, perfect for the engineer at the control panel. Installed this way, I can see the bass response being significantly reinforced by the soffit mounting. The 2 x 3” x 5.5” port alignment has a falling bass response below 50 hz, somewhat like the sealed alignment of my Yamaha SN-690s. Bass is deeper but less punchy. The boundary reinforcement should produce a balanced sound.

From my understanding, the 614 is a general use utility cabinet. I’ve seen photos of them hung from ceiling joists, on the wall, or in corners. I don’t know what the intended tuning was, but it appears to be biased toward midbass Vs. deep bass. @John Frum ’s post shows a slight 54hz bass hump that in his opinion would contribute to a punchier, stronger midbass that falls off rapidly below 48hz. I could see this enclosure sounding boomy when placed close to the wall.

Porque no los dos?

By design or coincidence, the port area of two 3” ports in the 9849 is 14 square inches, the same as the 2” x 7” port of the 614. Port length can range from the 3/4” of the 614 to 5.5” of the 9849. If we install and adjustable port or one that where we can replace the port tubes we can tune the speaker based on position in the room or the amp being used. I would think about a flange mount `with PVC or cardboard tubes. It would be easy to reverse the port tubes and mount from the inside with the tube sticking out. Adjust the tube length until tuning sounds right for your room and system and install as normal.

Edit to add: the response curves were for a 414-8C. I’ve seen graphs for these drivers and for 414As. The 414A has a rising response and the 614 may provide the midbass boost it needs. In either case, using two round ports allows for tuning whereas the rectrangular simple port does not.
 
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In either case, using two round ports allows for tuning whereas the rectangular simple port does not.
Using the rectangular port with a window to adjust opening could work. Similar to a gate valve. Felt for the guides and a means of tightening once adjusted.
 
3.0 cu ft; same as the 614 cabinets just setup a little differently.

I chose the “let’s not reinvent the wheel” approach and basically built 9849 clones. Cabinet design plans are available online.

I took some creative liberties with the face frames and aesthetic. Also used @je2a3 crossover design.

So far, these are very impressive!
I like the treatment of the 9849 plan. It is a furniture grade (real furniture grade, not Altec furniture grade) version that looks a lot smaller than a speaker the size of a Harbeth 40.2.

They look a lot like a JBL C36. A bit larger but proportionally similar. Unfortunately, a set of legs to make the picture complete runs about $400 on Ebay.

I’m struggling with the form factor for my upcoming 9849 homages. While the 9849 proportions are pleasing, a taller, narrower and shallower version will not need stands and might work well in my room.

Some design inspirations include:

1. Furniture grade version of the 9849, similar to the pair built by @marantzfan. It might look cool incorporating the George Nelson Thin Edge profile to the face frame. This may be accomplished by beveling the plywood edge similar to Fostex horns.

2. Harbeth 40.2. This involves narrowing the cabinet as much as the 32A allows. The 40.2 is 17” wide. I think there is a way to meet that cabinet width with the 16.5” 32A but need to talk to my cabinet maker friend. I think the baffle details (rear mounting, visible screw heads) give a very “domestic monitor“ look.

3. Devore 0/93. This is a wide baffle floor stander. This would take the design in a more conventional direction. Squeezing dimensions lets us get the same volume in a 18” x 13.5” x 31” enclosure. This would be similar to @Salectric ’s speakers. A short plinth, Salectric’s Sound Anchors, or other feet would all that would be needed.

4. Edit to Add: the Graham LS5/8. This is really another take on the BBC large monitor speaker, similar to the Harbeth 40.2.

Edit: I just read my own options and realized what I want is a @Salectric - style enclosure, needing only a plinth or low stand. I would think the BBC Monitor style would work well with these proportions. The baffle could be mounted with a reveal and thin edge style. I think this semi-industrial style works well with the richness is nice veneers.
 
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ICTWoody

Junior Member
Hey guys, just to bring this back to porting for a minute...

I think I've settled on porting my cabinets on the bottom with the 8"x2" round corner slot. But it got me wondering... does port location, when its this big, and with woofers with a low excursion like the 414, where the port is located in relation to boundaries?

I ask, cause I'm planning on making dedicated stands for my speakers, so relative to the floor, the port won't change from that boundary (the floor). But IF I were to rear port them with the same port so that if it needed to change it would just be a matter of a new back panel (easy) would that be detrimental to placement?

The only reason I ask, is there is a chance where I try these out in my small room (12.5x16.5x9') and in there it would be optimal to have them up against, or at least close to the wall. Assuming the port was the same (8x2x7/8" rounded rectangle) and they were on say 8-10" tall stands that didn't interfere with the port... is there any actual difference than being rear ported and 8-10" off the wall?

What about putting them up against the wall and the bottom port being closer to the front? or middle? or back of the speaker? Is there going to be any appreciable difference in sound?

- Woody
 
It is also a lot more flexible. I have a pair of rear-ported monitors with wool socks in the ports because they are close the the wall.
 

ICTWoody

Junior Member
Well... I’m a slut for aesthetics — curse of being a designer and so a front port is out of the running purely for selfish aesthetic reasons. I had to make that call before I had the new front motor boards CNC’d.

So, with that condition...

- Woody
 

Audionut

Next Round Is On Me
Well... I’m a slut for aesthetics — curse of being a designer and so a front port is out of the running purely for selfish aesthetic reasons. I had to make that call before I had the new front motor boards CNC’d.

So, with that condition...

- Woody
A happy middle might be a bottom port placed towards the front and angle cut (45 degree slanting forward)? My 604’s are bottom ported this way and I wouldn’t change a thing.
 

ICTWoody

Junior Member
A happy middle might be a bottom port placed towards the front and angle cut (45 degree slanting forward)? My 604’s are bottom ported this way and I wouldn’t change a thing.
Kinda where I’m leaning. How high is the bottom of your cab off the ground?

- Woody
 
Woody you have mentioned preferring to skip the techno garble/ bunch of math. Damp the floor/stands beneath the port with dense wool or any non foam material.
 
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