With that serial #, tag it's definitely cast as are my 22700 series. If there's any steel 800 series I've never seen one AFAIK. I thought that was the big difference between 800-900 series.
GM
Been looking for a set of cast steel pot 808/802 drivers for field coil conversion. Just won this early 808 on ebay. Add is confusing, says it's for parts, it supposedly works fine when I asked the seller.
Vintage Altec Lansing 808b driver 8 Ohm | eBay
Anyway, the SN is 00954 making it an early unit. The sample cast pot that I dissected for measurements is SN 17283.
Am I correct that the early pots are all cast steel and it was the later pots that were machined steel? The cast pots have the rough textured finish on the outside, it's rather hard to say about this one that I just purchased.
I assumed that the cast steel pots are the early units as steel castings are rather expensive and casting is not EPA friendly. The machined steel pots are either machined from solid bar or it's tubing with a cap welded on and machined.
Thanks
BillWojo
With that serial #, tag it's definitely cast as are my 22700 series. If there's any steel 800 series I've never seen one AFAIK. I thought that was the big difference between 800-900 series.
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
GM, all the 800 series are steel. The early cast units are not cast iron, they are cast steel. Big difference in the actual FE content between cast iron and cast steel.
I had both types of 800 series drivers checked with a XRF hand held analyzer. Within seconds it gives a complete metal analysis and even matches it with an known alloy if there is a direct match. Gives percent of each element to 0.01 percent.
The main element that we are concerned with is FE or iron as that is what forms the magnetic circuit. The cast pot is 97.31 percent FE and is a perfect match for 1215 steel alloy. The machined steel pot is 98.23 percent FE but oddly enough didn't cross to a alloy in the XRF's library.
Even though the cast pot is slightly lower in FE content I choose to use it over the other style pot because the side walls are substantially thicker so the overall FE content is much higher.
I think the non cast pots are either machined out of solid bar (expensive) or a weldment made up of a pipe and cap, machined after welding.
By the way, when using the XRF analyzer, one must grind through any plating before checking. Good news is it is confirmed that cast pot units are cadmium plated and the others are zinc plated.
BillWojo
Yeah, didn't take the time to check it before posting.What I meant was:
"If there's any machined steel 800 series I've never seen one AFAIK. I thought that was the big difference between 800-900 series." Since I quit following Altec in '75 except when the distributor had something new to show, these forums have been a bit of an eye opener as to what all mishmash they were forced into cobbling together
Thanks for the steel primer.I'm a little confused now though; what all are you referring to?: 'both types of 800 series'
GM
Loud is Beautiful if it's Clean! As always though, the usual disclaimers apply to this post's contents.
900 series = all ferrite, you guys know this, i know you do.
Prior to 1974 all small format drivers were pipe and plate welded construction.
Late in '74 introduced the newly designed cast steel pot on the 416-8B woofer, some 420's would also get the new motor.
The HF drivers wouldn't see them for at least another year. The 1975 literature shows a model 802-8E with the new style rear cover, but there is no way to be sure if it was ever produced or what magnet structure was used. I have never seen an 802-8E either in the flesh or a photo.
The 1975 pro catalog lists and shows both the 808-8B and 802-8E, but there is no mention of an 802G before 1976.
Another pure guess on my part, but i am wondering if the earliest 808-8B's still used an annular slit metal phase plug. The reason this comes to mind is that i have 9849's with 23746 drivers. 23746 is a very unique driver among altecs as it is an 806 size motor. But, it uses the new style cast return pot, and my 1975 examples have annular slit metal phase plugs. The clincher here is that this exact same driver can also be found with the Tangerine phase plug in it. I believe Ronsss has one and has shared pics of it here in the past.
Just wanted to share my thoughts and musings.
Not all vegetables make good leaders.
http://i86.photobucket.com/albums/k9...iver_Parts.jpg
GM, this photo (thanks to dgwojo) shows the difference in the pot structure between the two types. You can clearly see the thick walls of the cast pot vs the other newer style.
Not known is if there was any performance difference between the two.
The cast pot style has not only a rougher cast texture finish but a slight taper to it to facilitate release of the pattern from the mold at the foundry.
BillWojo
The newer 80x series pots are the ones that were cast.
A cast pot apparently makes for a better magnetic return circuit .
The change-over happened before the 802g came into existence , sometime during the life-span of the 802d .
I have a pair of 802d cast pots that are identically shaped ( except in their black colour ) to a pair of 802g ( this also includes the slight taper seen at the snout of the driver ).
The taper can be used as a give-away ( for a cast pot ) to the sharp eyed .
Last edited by Earl K; April 15th, 2017 at 07:04 AM.
I would guess the welded assemblies could have certain variances as the welds/joinery vary. I can see where the cast structure would be much more uniform in that respect.A cast pot apparently makes for a better magnetic return circuit .
Not all vegetables make good leaders.
This is what this forum is all about. Not the stuff that could make it the Altec User's Asylum.
Opinion is only as valid as its verifiable supporting evidence.
So I had this all wrong in my head thinking that Altec started with cast steel pots and changed to the welded construction later on.
Well that sucks as the serial number on this 808-8A is 00954 making it a very early one.
BillWojo
Last edited by BillWojo; April 16th, 2017 at 05:09 PM.
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