Cabinet Size, Cubic Feet, Ports, for Altec 803b bass speaker

GM · November 29th, 2016, 10:35 PM

Originally Posted by Elitopus1

Its the same woofer besides the impedence. You would just have to adjust the xover values

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416Z=416A minus the magnet cover

Hmm, Fs is ~same, Vas is lower [indicating a smaller cab], but without the pot, Qts is way higher and since this dominates, the cab for the 'Z' typically ideally needs a 2x bigger cab.

That said, the 803B/416A was designed to be driven with a high output impedance [low DF] whereas the 416Z was for higher DF, so match them up with period correct electronics and both will need 'close enough' the same alignment [net Vb, tuning to Fs]

Using T/S without taking history into consideration yields alignments only suitable for modern very high DF amps.

GM

**Elitopus1** · November 30th, 2016, 12:40 AM

So a 416a that has a 21184 cone and a 416z that has the 21184 cone have different specs? Is there a motor or VC difference?

Just curious if its just the 8 or 16 ohm impedence that makes a difference. Maybe I am missing out on something by running 8 ohm gear.

And just to clear things up I am not arguing with you guys. I'm sure you are right. I was always taught that the 416a is the same as the 416z. The Z is just the version without the magnet cover.
I was also taught that the later 803b with cloth suspension is the same as the 416a with the earlier 803a being closer to the original 515 but with a smaller motor.

I know the VC is a different length with 8 or 16 ohms but I have always heard for HiFi that there is no "better" impedence. At least when using solid state amps

**bowtie427ss** · November 30th, 2016, 08:38 AM

So many little variations, and they are loosely documented, or not documented at all. Things like dampers/spiders of varying compliance, various surround dopes(Altec likely used at least 3 or 4 variations over time) with different viscosities and damping characteristics.

Something as subtle as changing the dimension of the chamfer on the nose of the pole piece can measurably alter parameters.

Altec is rather infamous for making subtle changes without notation, or re-designation of model number.

Some of us are aware of 825/828 cabinets with different throat tunings among them, i challenge you to find any published documentation or notation on this.

How 'bout those red surrounds?

On 414's too.........................

It's only because of minds and memories like GM's that details like this get brought to light.

**Elitopus1** · November 30th, 2016, 10:17 AM

So then whats up with the red surrounds? I wonder if anything else about the driver is different or if they just got a "deal" on some red ones

It looks like with all the variations on the 803/416 that one should probably test their drivers with a woofer tester before designing a box around them

**bowtie427ss** · November 30th, 2016, 10:53 AM

So then whats up with the red surrounds?

I wish i knew the answer. Maybe as simple as a temporary scarcity of the black fabric in the supply chain. Certainly there is an explanation somewhere in the past. But, it may be lost by now.

One thing for certain, they reveal that the surround dope used with them was a very clear/transparent product. It also appears that the red surrounds were colorfast. I've never seen an instance where it looked like the red dye was bleeding into the dope like the dye from the black surrounds does.

It looks like with all the variations on the 803/416 that one should probably test their drivers with a woofer tester before designing a box around them

If you have the means, every electrical component should be tested prior to launching any serious build.

**SanJoseMichael** · November 30th, 2016, 01:07 PM

I have not pulled the driver from the cabinet, but from a photo I'd taken from behind, they appear to be treated.

Photo:
http://s397891146.onlinehome.us/edge.jpg

Thiele-Small parameters for 416-8B were found here:
Altec Thiele-Small Parameters

But I don't think 803b (16 ohm) = 416-8B (8 ohm) to use those parameters.

Hence "Figure 24" is as good as it gets for smaller cabinets.

**gdmoore28** · November 30th, 2016, 01:36 PM

I cannot tell you guys how helpful your Altec knowledge has been to me. I spent fifteen years doing ProSound installations, lots of it Altec, but never paid any attention to the nitty-gritty elements I'm now learning. We just went with the recommended Altec pairings and did our best to time align, adjust delay settings, etc. etc. with tools available at that time - ie, zero computer-aided solutions other than early RTA units.

Just about the time I think I'm beginning to get SOME handle on Altec lore, here comes one of you guys to blow my assumptions right out of the water - and I love every bit of it!

No, none of this knowledge will solve the world's problems, but it sure does enhance the hobby.

Thanks for all your wealth of knowledge.

GeeDeeEmm