N-501-8b Inductors

[dread64]

GM, Marty,

That's quite alright, my friend.
I would send you a schematic, but I don't have one.
And I'm not very good at making them. Reading them? Yes. Drawing them? Yikes.
I just Googled "Altec n501-8b". There seems to be quite a few of them floating around.
Anyhow, once the parts all arrive, and the soldering is done, I'll let you guys know how it came out.
Again, Thanks for everyting!
Dave

[martyh45]

Just so happens I drew one up this morning  You will notice I didn?t label the inductors as I am not sure what they should be, I measured some from an ?A version and only got .306mH. I don?t know if the iron cores are not measuring well on my hand held or what. I can send one of the coils from the 8B to someone with a bridge if they would like to measure them.

[martyh45]

Another interesting note: The first one I started to trace had the bottom of the 28uF cap on the low pass floating. It was soldered to the wrong pin.

[martyh45]

Oops, that should be ??.. and only got 3.06mH? two posts above

[dread64]

Marty,

Well, I hope your meter is working properly.

And all those years that cap was soldered incorrectly, and no one noticed a problem with the sound?
Interesting.

Dave

[GM]

Greets!

Thanks Marty!

OK, we have a N501-8A with CD horn compensation/woofer zobel unit #30904 except adjusted for the Valencia, etc., so should have had a new model number such as N502-8A or some-such.

Anyway, since I couldn't find anything, it appears to have been a stop-gap XO before the across-the-model-lines switch to the adjustable N1201 series. Regardless, if you're system has a N501-8A and not running a high output impedance amp and/or other filters, at a glance this looks like a good upgrade for those seeking a Hiraga style XO for the 511/811, 416/515 loaded cabs. Someone will have to at least sim it using actual driver measurements to see just how much of an upgrade it is though.

GM

[martyh45]

IIRC, every one I have ever seen came in a cabinet with a 902 on a 511 horn. I?ve only had 5 of these so it isn?t exactly what you could call definitive survey. I thought the a7-500 was always loaded with a 416 type so perhaps they were optimized for this combination.

Dave,
I hope it?s reading right on the iron cores too. I have checked more of the Solen air cores I have on hand and they all measure very close to the stated value I.E. a 4.7 measures 4.73, a 1.1 measures 1.11 all within a 1% tolerance. I don?t have any new HQ Iron cores around so I can?t double check against that type. The measurements I got on the 8A coils were within 15% of the value GM gave. Perhaps they drifted a bit or the spec was that loose to begin with.

[bowtie427ss]

Here's a source for some hard to find network schematics. Sorry, only the "A" version of the 501-8 is listed.

http://www.altecpro.com/products/vin...ex.htm#ceiling

If you scroll down into the list of ceiling speakers, a schematic can also be found for the 604-8G network.

[bowtie427ss]

errrrrrr, check that the 604 network schematic is found in the "duplex" list NOT the ceiling list mentioned in the previous post.

[GM]

Originally posted by martyh45:
IIRC, every one I have ever seen came in a cabinet with a 902 on a 511 horn.

<font size="2" face="Verdana, Helvetica, sans-serif">Greets!

902 or 902T (has loading cap)? If the latter, then apparently this is a custom XO for the A7-500 after the switchover to the 902 series to adapt it somewhat to the 511 while maintaining the same power rating as the then new 1200 Hz A7 with 511. Since the 902T wasn't around long, I assume neither did this version of the A7-500.

Then again, in '84 the A7-500-8E lists a N8500-8A, so did they finally get around to renaming the N501-8B or is it yet another variation on a scheme ?

Inquiring minds want to know..........

GM