Mine are 414A. 414Z numbers same?
Mine are 414A. 414Z numbers same?
More or less.Originally Posted by Drugolf
Unless you are prepared to learn how to measure your own driver's TS parameters then it's best to not fixate over numerical differences ( as if they are the deciding factor here > they're not ! ).
Woofers as old as yours are ( dollars to donuts ) no longer up-to-spec, so my advice; run the WinISD numbers and learn something .
Oops, I posted this in another thread too but probably should go here as a follow-up.
SO here is my initial Winisd graph for a Malibu configuration box. There are two of the 411A woofers and using the plans it appears that the cabinet volume is 7.5 Cf. I took that down to 6.8 for loss for bracing drivers etc.
Sealed box. .707 Max Flat amplitude response alignment.
Does this appear as it should? What is it telling me?
Hi Drugolf,
Congratulations, your first LF modeling! A few general comments.
So what you have as box overvolume for loss, drivers and bracing for a 6.8 cu. ft. enclosure is 10%, not a whole lot for that size, probably the bare minimum. Which QL number did you use for modeling? Default?
Win ISD default response is max flat amplitude. But you are not obliged to stick with that you can modify LF response, in this sealed box case, by changing cab volume: larger = more dropping LF and smaller = flatter LF.
It does look like a max flat response babana shaped, some like some don't, with a typical sealed box roll-off.
To me it appears like a too large box generating an early roll-off response, and to someone else it could mean great because he had intended to place the box at the junction of 2 or 3 boundaries therefore raising the low frequency output. But I'm not familiar with the Malibu configuration...
You decide what suits your expectations vs use and box placement. However, you can possibly do better LF wise with a vented box (or smaller sealed volume without being max flat?).
Any reason (e.g. driver Qts?) why you have not modeled it as a vented box? Regards,
Richard
Thanks RMC. I did not adjust Ql for this initial effort/test on my part. But I get what you explained earlier and wen I actually know I am doing this correctly otherwise, I will make the adjustment.
EarlK isn't comfortable with my results so he is checking on his end for me.
Hi Drugolf,
Your Vented box modeled in the other thread is tuned too high giving a quite bumby LF response: + 4.5 db @ 75 hz which may not be desirable sound wise.
By tuning it lower you WILL reduce that LF peak and probably reach a little further into deep bass than the sealed box.
RE: "Tuning Freq on the green vented line I adjusted to 40 (see I remember Earl)."
As far as I recall Earl didn't say one must not tune below 40 hz, period. If I'm right he said that an Fs 40 hz driver should not be tuned lower than Fs, 40 hz in the case mentioned earlier regarding another woofer.
However, here the data you entered in Win ISD shows the 411 driver has an Fs of 18 hz (confirmed by the spec sheet I have). Therefore you are NOT limited here by the "40 hz tuning rule" with the 411 woofer, but rather by the "18 hz tuning rule". I would try again with a tuning frequency in the 30-35 hz or so range to try to get a flatter LF response from the box. Doesn't have to be perfectly flat, but I usually try to stay within one db or so...
Though Altec's recommended enclosure (4.5-8 cu.ft.) is sealed box, driver having EBP at 48.7, it can still be used in a vented box to benefit from vent(s) LF distortion reduction. As indicated by Eminence in "Understanding Loudspeaker Data" re driver EBP: "This is merely a starting point. Many well-designed systems have violated this rule of thumb! Qts should also be considered." And here the Qts you entered in Win ISD for 411 is 0.33, certainly not an "out in the field" number for a vented box, in fact many with such Qts number are loaded in vented.
Finally, a single 4" port isn't a reasonable assumption for a TWO 15" woofer box. TWO 5" dia. min. ports would definitely be a better choice as long as length fits properly in the enclosure, if not you bend the vents or try just a bit smaller diameter ( 4.875, 4.75 or 4.5) and see where it leads to length wise... Regards,
Richard
Thanks Richard. I see what you are saying there with teh Fs for the 411. I didn't catch that it was down that low. I will carry on with doing some modeling as I determine some potential builds with these particular drivers. I am expanding on that aspect over in my other VOTT thread.
Just a FYI, the 411A is 12"
Hi Drugolf,
Sorry for the driver size, my mistake then. Since data sheet didn't give nominal woofer size I guess I concluded too quickly from its 15 5/16" diameter and 14 3/16" mounting hole it would be a 15".
An unusually large 12" though VS my two pairs of 12s having diameters of 12"+ and mounting holes of 11"+ ...
Since these woofers are oversized compared to usual 12 inchers, two > 4" vents may be more appropriate.
BTW Though EBP and Altec may indicate or suggest that 411 is more suitable for sealed box, it does not mean it is automatically unsuitable for vented box use. Regards,
Richard
The 411-8a is very much a 15" woofer ( by all definitions ).
411-pdf from GPA
Perhaps you're thinking about the Altec 412 ?
Thanks Earl for the precision.
I initially used the exact same 411A spec sheet from GPA dated 9/75 as Earl posted to indicate it was a 15" driver, at least in my view. But I could have been wrong which I readily admitted, though it seemed curious to me.
When I googled "Altec 411A" the first item in the results was that pdf spec sheet from GPA, I relied on it since GPA is a known reliable Altec source in absence of the manufacturer... Regards,
Richard
OOps guys, I'm sorry. My bad yes 15" for the 411. I was typing 411 but thinking 414 like I am using in my actual build thread. Altec and there darn numbering system. Tough on us newbies.
The data here has been for the 411. I will continue this for the 414A's over in my other VOTT thead where I am aiming for the Mailbu build.
Hi Drugolf,
I'm a bit confused here. Are you building ( or rebuilding ) a malibu with 414',s Or a total re-think with 411"s?
On the Issue of venting the 411's ; it can be done with good results, BUT BEWARE! The 411 is capable of going sub-sonic. Especially at high volumes. I have witnessed this. We vented the box the old fashioned way at around 20Hz. It was the one I described in your Santiago rebuild thread. I worked with an Altec commercial contractor on the design. Gadzooks did it reproduce low bass!
But warped records would send the cones into the outer realms.
Ed
KEEP ON LISTENING!
Hi Ed,
I agree with your BEWARE. And I'm glad to hear that "411s can be done in vented box with good results".
In his other thread "Altec custom VOTT something" Earl has also warned Drugolf previously about too low box tuning. In that same thread in post # 65 Drugolf wrote: "Richard in my parameters WINISD thread suggested I could drop the tuning down since the 411A FS is pretty low at 18.31."
Yes, but in the present thread in post # 21 I mentioned "I would try again with a tuning frequency in the 30-35 hz or so range to try to get a flatter LF response from the box." Not going subsonic. That was for the 411A box he modeled in Win ISD. Still away from subsonic range. And I hope Drugolf didn't get the idea that he should go as low as earthquake requires...
If he does go vented box as I suggested for lower LF distortion, prudence also dictates the use of a steep high-pass filter, as with most bass reflex cabs. For example, E-V suggests a HPF with an F3 at about 0.8 X Fb (e.g. a 30 hz Fb would then mean a HPF with an F3 at 24 hz). Regards,
Richard
Hi Richard and Drugolf;
If agree with the idea of the high pass filter use with a vented 411. I did mine in the mid '70's when all pre-amps and most receivers had rumble filters. I eventually closed up the box, and it was still good for 25 hz.
Have you ever heard the Altec 9848? By all the gods of Egypt that thing was good for 20Hz and it was sealed. Specs. are in the library.
Ed
KEEP ON LISTENING!
I have two things going on that I am trying to use Winisd with...or at least learn to use it with.
First is the potential Malibu build (or something based on the Malibu design) because I have 4 of the 414A woofers. That effort is the evolution of my VOTT Something thread. Those came in large homemade cabinets with 811B horns, 802-D drivers and a N-500-E network. The initial issue with those that EarlK identified was the poor port design and his suggestion to improve that aspect. This had me looking at Winisd to see how Earl came up with his recommendations. like I said, this is now evolving into a potential Malibu build.
Second, I had 4 Santiago's. I restored one pair fully as seen below. They sound great and yes, depending on what I am listening to they seem to be able to dig deep. Sealed cabinets with the 411's.
The 2nd set of Santiago's are where a new modified build will occur. The original cabinets on those were dinged up enough that we felt it would be best to start fresh. All original components and recapped so they wont need anything done with all of that unless called for with cabinet adjustments. The question in that thread was basically since we are putting in the effort to rebuild cabinets, are there any shortcomings with them related to the original cabinet design, particularly their size? Thus the Winisd exercise there.
Hope that clears up my mess a bit.
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