Pretty Reasonable 411-8A's

[GM]

FWIW, flared vents of the same length, base diameter as an un-flared one will be acoustically shorter, so will tune it a bit higher, sometimes enough to be audible. Also, the polar, roll off patterns of the 511, 811 are different, so the M19's XO may not work well with the 511 plus the bass bin ideally needs to be inverted to get the woofer closer to the horn regardless.

GM

[TubesNhorns]

GM, I thought that might be the case with the flares on the tuning and figured you'd set me straight.

From available graphs, I can calculate the required port area in square inches. However, calculating the depth of the port remains a mystery. How do you do it?

I calculate the internal cabinet volume at 6.2 ft^2 (woofer only, no horn or CD). With a resonance frequency of 25 Hz on the 416-8A, port area appears to be 30 in^2. I can fabricate a second 'port board' as these bolt into the cabinet in-lieu of the horn. I will make a rectangular port that can be 'shimmed' to change the port area.

I was thinking of starting with a 7.5" x 4" port. Does the aspect ratio (W:H) of the port have any influence? Would a wider shorter port make a difference? Would the depth of the port be the same in any instance?

I will invert the bins to place the woofer closer to the horn. Thanks for the advice.

[GM]

This looks familiar, didn't I already answer this on another thread/forum?

GM

[TubesNhorns]

packages arrived from Bill at GPA. Literature indicates that the 411 and 421 share the same bolt configuration. Mine are the Series II and are different. Cork gasket on outer side indicates mounting behind the motor board.

- - - Updated - - -

So, the 411's sold cheap. Also sold a set of 511 crossovers and used the proceeds to upgrade the 421's to 416 spec. Inverted the Santiagos and installed new risers. Installed the horns on top. Left room in the new horn enclosure to go to a larger CD as previously the 806's were right against the Santiago backside.

Too heavy to move into the garage so the final fitment and refinish were done in the living room. Wired to bi-amp. Almost ready to fire them up (finally).

[Phil-G]

Vintage Altec Lansing 416 8c Low Frequency Loudspeaker Woofer | eBay

this loooks like a 416 reconed 421. yea or nay?

[bowtie427ss]

Vintage Altec Lansing 416 8c Low Frequency Loudspeaker Woofer | eBay

this loooks like a 416 reconed 421. yea or nay?

Looks like a flat magnet(circa EV junk) version 416-8C to me, black spider and all.

[GM]

+1 Look familiar? Electrovoice Model 815 9997 15" Speaker Fresh Recone | eBay

GM

[Phil-G]

the back looks just like the 421s i have without the label. that speaker has vents front and back.

[bowtie427ss]

the back looks just like the 421s i have without the label. that speaker has vents front and back.

Do a google image search for 416-8C. You'll see a lot of examples where the foil cal has been pushed into the vent void.

On at least the early runs there would be a metal plate glued to the front of the pole piece blocking the vent passage to the rear. You'll find fellas here who encountered them when they fell off creating some fairly unpleasant sounds.

While quite similar, i'm not sure they are the same magnet structure as the 421, i think there is a difference in gap/plate depth. There are fellas here who know better than me, hopefully one of them can explain.

The "good" 416-8C's will have a slightly rounded, and bolted magnet structure.

[GM]

"the back looks just like the 421s i have without the label. that speaker has vents front and back."

Let's hope not or it won't perform as it should in either a vented or sealed cab. The point I was trying to make with the link is the lack of quality in the EV's casting compared to Altec's more machined looking finish.

GM