New Guy

**Greg_M** · September 8th, 2011, 07:55 PM

Back in the late 60s I played bass through 4 Altec 421A (two cabinets). It all got ripped of in 72 and That was the end of my musical career.....I thought. Now I am gathering up stuff to play again. First out of nostalgia, and then I got the bug again. I always wanted a Sunn 200S so I built/rebuilt one of those to play The Jazz through. My greatest setup was the 421s and so I got one and then another. Having learned something over the last 40 years I started looking for parameters for the 421A and have been all over the net and finally wound up here. I find it really odd that these parameters are so darned hard to come by. I searched here (maybe not well enough) and couldn't find anything. All I have is the Altec Spec sheet which doesn't have a lot on it.

The only reason I want the specs is that I'm not exactly sure what I'm going to do with the 421s. If I have the specs I can put them in anything. HiFi, bass, whatever.

So anyone got those sneaky parameters?

Thanks

**voice of the theater** · September 8th, 2011, 08:11 PM

Maybe (one of) these will help?

http://www.altecpro.com/pdfs/vintage...%20Speaker.pdf

http://www.altecpro.com/pdfs/vintage...%20Speaker.pdf

http://www.altecpro.com/pdfs/vintage...%20Speaker.pdf

**Greg_M** · September 8th, 2011, 08:20 PM

I've got those and all though they have a couple items, they don't have the Thiele/Small info I am looking for.

But thanks for the effort

**voice of the theater** · September 8th, 2011, 08:42 PM

This should help....

Thiele/Small Parameters for Altec LF Loudspeakers

**Cal Weldon** · September 8th, 2011, 08:45 PM

Here's what Ron measured his 421A's at:

Re - 4 ohms
Fs - 38 hz
Qms - 4
Qts -.3
Qes - .33
Zmax - 52 ohms
Le - .49 mH
Vas - 8.5 cu ft
Eff - 3.86 %
Sens - 97.8 db/watt/1 m

If yours is an 8 ohm it may be an older version?

**Cal Weldon** · September 8th, 2011, 08:46 PM

Originally Posted by voice of the theater

This should help....

Thiele/Small Parameters for Altec LF Loudspeakers

No 421A's there. A bit tricky to dig up.

**voice of the theater** · September 8th, 2011, 08:55 PM

Originally Posted by Cal Weldon

No 421A's there. A bit tricky to dig up.

You're right--they are conspicuously absent.... I'm saving the chart to my hard drive anyways--a nice resource to have....

**Greg_M** · September 8th, 2011, 09:01 PM

Originally Posted by Cal Weldon

Here's what Ron measured his 421A's at:

Re - 4 ohms
Fs - 38 hz
Qms - 4
Qts -.3
Qes - .33
Zmax - 52 ohms
Le - .49 mH
Vas - 8.5 cu ft
Eff - 3.86 %
Sens - 97.8 db/watt/1 m

If yours is an 8 ohm it may be an older version?

From the numbers on the basket (etc) I believe it's a 70ish model
Thanks for those numbers

**Old Guy** · September 8th, 2011, 10:04 PM

Just a couple addendum's I think the 421a was absent since it was discontinued years before the list.

If the 421 is original would suggest using the 8H specs, Same cone but higher temp coil.

If reconed, current parts are closer to the 8hII.

Suggestion? Post to CL to see if there is a neighborhood geek who may be able to measure yours. Some guys would do it just for the fun of it.

**Greg_M** · September 8th, 2011, 10:06 PM

Originally Posted by Old Guy

Just a couple addendum's I think the 421a was absent since it was discontinued years before the list.

If the 421 is original would suggest using the 8H specs, Same cone but higher temp coil.

If reconed, current parts are closer to the 8hII.

Suggestion? Post to CL to see if there is a neighborhood geek who may be able to measure yours. Some guys would do it just for the fun of it.

Thanks for that.
I'll have to call my recone guy and see if he can do it or know someone