ICTWoody
No longer a junior member
Spot on.
I'm real dumb, guys. Sometimes when I ask these questions I just want to be told what to do. This is like a conversation with my girlfriend.
- Woody
Spot on.
Lower and faster.This is like a conversation with my girlfriend.
I like the slot ports cause that is what Altec did a lot, but should I consider using PVC round port tubes so they could be friction fit and changed easy if we need to adjust?
The perfect is the enemy of the good.
I'm far too insecure to tell anyone what to do.I'm real dumb, guys. Sometimes when I ask these questions I just want to be told what to do. This is like a conversation with my girlfriend.
- Woody
You can always add louvers for fine tuning.So what you're saying is a 2"x8" hole in the cabinet with rounded corners is a good starting place? Cool.
I've told the vendor to move forward with the baffles, I'm going to port in the bottom.
I like the slot ports cause that is what Altec did a lot, but should I consider using PVC round port tubes so they could be friction fit and changed easy if we need to adjust?
I really think I'm overthinking this and I should just use a 2"x8" hole and call it good.
- Woody
Since we are compromising anyway, why not start with a 2” X 7” like in the 614? Speaking of which, has anyone modeled the 614 (3.2 cu ft, 0.75” x 2” x 7” rounded corner port) in Bassbox Pro?So what you're saying is a 2"x8" hole in the cabinet with rounded corners is a good starting place? Cool.
I've told the vendor to move forward with the baffles, I'm going to port in the bottom.
I like the slot ports cause that is what Altec did a lot, but should I consider using PVC round port tubes so they could be friction fit and changed easy if we need to adjust?
I really think I'm overthinking this and I should just use a 2"x8" hole and call it good.
- Woody
Since we are compromising anyway, why not start with a 2” X 7” like in the 614? Speaking of which, has anyone modeled the 614 (3.2 cu ft, 0.75” x 2” x 7” rounded corner port) in Bassbox Pro?
Next time just @ me. All speaker designs are compromises.
The difference between a 2" x 8" x 3/4" port and a 2" x 7" x 3/4" port in Woody's cabinets is a tuning frequency of 45 Hz vs. 43 Hz. This is hardly noticeable, and falls into the category of distinctions that will be swamped by cabinet damping and placement.
A 2" x 7" port is definitely on the spectrum I laid out of possible tuning schemes for Woody's cabinets, but tuning is dependent on both port dimensions and cabinet volume. Starting with a 2" x 7" on the basis of, I guess, being good enough for the 614, doesn't strike me as sound. Such a port tunes the 614 to about 54 Hz, but tunes the 5 cu. ft. cabinets to about 43 Hz. And that works fine, but getting there because you selected the port size based on the 614, rather than any understanding of cabinet tuning, is a happy accident.
If you're looking for a response like the 614, the alignment that's going to get you the closest in 5 cu. ft. cabinets is actually the 2" x 10" port that tunes them to 48 Hz. The curves are really similar, but the larger cabinets have better extension.
Thanks!
@John Frum could you model the Altec 614 vs. 9849 enclosures? They are both 3.2 cubic feet. The 614 uses a simple port, rectangular with rounded corners, 2” x 7” x 3/4”. The 9849 is the same dimensions (other than internal bracing and the horn/driver) with 2 x 3” dia x 6” d round ports. The actual ID is slightly smaller, but it seems in the Altec world the drivers tolerate a wide range of alignments.
Many thanks in advance,
R
I took that as a challengeI can’t find it, but there is an Altec advertisement showing the 9849A soffit-mounted in in the control room. I would expect bass reinforcement from the near boundary mounting of the wall and ceiling.
Would you be willing to run the 414A thrPugh the same simulation?
I took that as a challenge
I failed, but I did find some cool old Altec ads, etc.
e.g.,
View attachment 28398
View attachment 28399
source: https://worldradiohistory.com/hd2/IDX-Audio/Archive-REP-IDX/IDX/70s/Recording-1974-12-OCR-Page-0051.pdf#search="altec 9849a"
@John Frum I looked at the 9849A drawing again and scaled the port tubes at 2 x 3” ID x 5.5” L. I can infer what the response change would be but it would be interesting to see how minor port length tweaks will change response.Based on your internal volume and port dimensions, the 614 is tuned to 54 Hz and the 9849 is tuned to 35 Hz. Very different presentations.
Traces generated using 414-8C T/S parameters. Yellow is 614. Red is 9849. Despite the lower output under 48 Hz, I'd likely prefer the punchier 614. Different drivers will yield different results.
View attachment 28395
I Measured my 4 414A's and this is where they came in. if something looks off, let me know.I would, but you'd have to rustle me up some T/S parameters. I don't have that one.
Edited it with new tests on each of them.The Znom is 18 ohms and the efficiency is 90.59. Both seem a bit off.