Help on Altec N501-8b

[Earl K]

- Thanks for taking the time to rip apart your newly won prize ( ).

- I realize that it's a major PITA / but anything that you can add to the spotty bit of Altec info that we have here / is much appreciated .

- I'm happy to eat my words ( about it being a "cheapened 501-8a" ) btw .
- From what you've said so far, my speculation is tending towards Altec having included an HF contour circuit for the horn ( ie; inline RC combo ) .

- Anyways >< muchos Thanks !

[sbjacob]

- Thanks for taking the time to rip apart your newly won prize ( ).

- I realize that it's a major PITA / but anything that you can add to the spotty bit of Altec info that we have here / is much appreciated .

- I'm happy to eat my words ( about it being a "cheapened 501-8a" ) btw .
- From what you've said so far, my speculation is tending towards Altec having included a HF contour circuit for the horn ( ie; inline RC combo ) .

- Anyways >< muchos Thanks !

My pleasure as this is my way of stress relief. I may put these on boards as I need to build another pair.I like Clarity SA caps combined with %10 of the cap value with Mundorf Supremes.

[Russellc]

- It was used with the A7-500-8E system, consisting of a 828E cabinet / 902-8T on a 511b horn / & 416-8C for a woofer .
- This info was findable in the LHF library ( even though it's not searchable using the sites' search-engine ) .


- As far as the N501-8b schematic, I really doubt that it's anything more than an updated version ( ie; cheapened enclosure ) of the N501-8A whose schematic can be found over at Altec Pro ( use Google ) .

- You've got one, open it up , compare its' cap values to those of the N501-8a, & post the results so the rest of us can learn something from your thread .

>< cheers

I have a set of the 501 8b, it came with my 828 cabs, 902 8b and 416 8c.
Dont think its the same as 501 8a, I've seen that schematic, this one has a bizzillion resistors, which I didnt see in the 8a version.

russellc

[Russellc]

Most of the Altec home VOTT systems crossed at 800 not 500, but I beleive these 500 crosses were used in the Barcelonia and Santiago systems.


I think:
Barcelona = 411 woofer, 806 HF, 511 horn, 500 cross
Santiago = 411 woofer, 806 HF, 811 horn, 500 cross

...but I could be wrong... ..you can search here to confirm.

500 hz was also used in the A7.

Russellc

[Russellc]

I opened up and is similar to the N501-8A however there is are a few more caps.I replaced the 3uf cap and added a Dayton Film and Foil bypass cap .47uf on the 28uf caps until I can get some new ones.I will post inductor value later as I can not find my leads on my inductance meter.Also I will post ohm and watt of the resistors and when I get time post a schematic.Attachment 39959

Thank-you, it will be much appreciated. I was never able to find the schematic on line.

Russellc

[Earl K]

Don't mind me, I'm just doing some housekeeping here !

I have a set of these x-overs ( N501-8B ) that I am recapping. Does anyone have info on the inductor values? I would like to replace them with higher quality inductors, but not sure what mh they are. Any help would be greatly appreciated.

I measure 2.7 mH and .3 Ohms DCR with a hand held meter. I checked the meter with some solen air cores I have on hand and both the dcr and inductance were within tolerances of the published values.

Both the same? I see two in the box.

Yep, one measures exactly 2.67 mH and the other 2.71. The dcr is the same for both as is the part number (18236).

Greets!

FWIW they should be ~3.6 mH.

GM

And please don't tell me I just ordered four
of the wrong inductors.

Geez.

Dave

You did not screw up ordering the 2.7 mH inductors. The 2.7 mH ind (for both inductors) + 28 uf cap will give a Butterworth crossover at 580 hz.

That's good, gets the crossover up above the 511b's cutoff.

All,

I've finished this little project using Jantzen coils and caps. The 2.7mH coils seem to have worked out just fine. The only problem I've encountered is what I believe to be a weak solder joint in the left channel bass section. I will be slaying this dragon tomorrow. At any rate, when the bass isn't cutting in and out in the left speaker, the sound is way better than it was with the stock 1285 x-overs. So in my opinion the effort was well worth it. Once I've trouble shot the intermittance issue, it should be heaven.

Dave

All these imbedded quotes are taken from this thread, over at Hostboard .

<> cheers

[Altec Best]

A year late You know what they say better late than never Thanks Earl.

I was just messing with the N501-8A the other day.And why I was looking for some info on them,I was thinking that the 8B was the same until I found this thread.

[Art J.]

Hey Gang, was it finally confirmed that the 8B was a combination
of the 8A and the 30904 as in the preliminary diagram?
I only have an 8A here and the equalizers.

[Earl K]

Hey Gang, was it finally confirmed that the 8B was a combination
of the 8A and the 30904 as in the preliminary diagram?
I only have an 8A here and the equalizers.

That "preliminary schematic was drawn up by "martyh45" . He ( presumably recognized, & ) drew the "HF EQ" circuit into the schematic that he created .

The assumption here was that he had these 8B" crossovers to work from .

He later measured both coils with in the 2.7 mH region ( he even pointed out the part number of the "8B" coil is different than the "8A" version ).

There is a difference in the value of the coils .
- 2.7 mH vs the 3.6 mH of the "A" version .



<> cheers

[Art J.]

Interesting, thanks Earl. The only way I can calculate a 2.7mh coil to work
is if matched with a 21 uf cap, which raises the crossover point to 650hz.
I think the mystery still continues with this one.....................


On the light side, I found this Hi-End crossover circuit on one of my
Ham Radio sites. Its easier to post it here, plus the other site has been
too grumpy lately anyways...........

[Altec Best]

Its easier to post it here, plus the other site has been
too grumpy lately anyways...........

Hear Hear !