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Altec N-3000F XO rebuild.

gogofast

gogofast

Addicted Member
i just opened up the N-3000F crossover for my Seville's. much simpler than i expected, and getting those tar off was easier than i anticipated. :thmbsp:

looks like 2mfd oil can cap and another 6mfd cap plus 25ohm resistor ('brown devil' :scratch2:) and the tiny coil. i'm gonna try getting some high-end caps
for these, but i need some help figuring out the following:

1. should i leave the oil cap?
2. change the 'brown devil'?
2. what should i replace the inductor with (type, value, awg)?
3. inductor has three wires coming out of it instead of two how come?

thanks for any help and i will post pictures as i rebuild it. it wont be as nice as dgwojo's crossovers though...:no::D

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thanks for the reply.
the speakers are lacking detail in very noticeable way. that's why i wanna rebuild these xo's. i don't have a capacitor testers to test these caps and hearing that oil caps will last almost forever...i don't wanna replace it without good reason. how do these old oil caps compare with today's higher end caps? so you think i should just leave the inductors? if i do replace them, how do i find out what two inductor values to replace with?

oh, and the tar just came off with screw drivers. it was at room temp. and was kinda soft.
 
If it 'twer me, I'd be swapping out both caps to begin with then temp wire the crossovers into the circuits for listening tests. We're talking about a few $$ and a bit more in shipping, if you use something like Solens.

Next, once I was able to verify that the crossover caps did indeed improve performance, I'd swap back in the oil cap to see what differences I'd hear. The other cap, though, I'd replace.

Lastly, I'd be evaluating the overall costs of just building a new version of the whole crossover and reinstall the original components back into the original canister. Reason is that I believe they're worth more intact. The key, though, is determining the value of the tapped inductor.

Cheers,

David
 
I just did a quick internet review. Nobody knows poo about N3000 on the Altec Forum, apparently, and there are a half-dozen inquiries over time. There appear to have been eight iterations of that crossover, versions A-H. The situation is summarized in this post at AA:

http://www.audioasylum.com/forums/hug/messages/12/129504.html

A possible substitute design is suggested there, but my bet is that it will suck. It'll only cost about $20 to find out.

If you want to pack that crossover back together with pieces of foam to protect the components inside and send it to me, I will document it. PM me accordingly.

THEN, if I were you, I'd reassemble it and sell both the crossovers and the tweeters, from which funds, I'd upgrade the Seville(s) (is it one, or a pair you have?) with modern horn tweeters and crossovers.

Yes, I have a design in mind, but I don't know Seville from a hole in the ground. I do know 414s are quite competent woofers, assuming that's what you have.

Here's the result of a recent non-Altec upgrade using the design I would propose:

attachment.php


I'm sensing a trend here. You don't like Santiago, and you don't like Seville. That's not intended as any measure of insult; perhaps it goes more to you becoming a discerning listener.... :yes:
 
Zilch said:
I just did a quick internet review. Nobody knows poo about N3000 on the Altec Forum, apparently, and there are a half-dozen inquiries over time. There appear to have been eight iterations of that crossover, versions A-H. The situation is summarized in this post at AA:

http://www.audioasylum.com/forums/hug/messages/12/129504.html

A possible substitute design is suggested there, but my bet is that it will suck. It'll only cost about $20 to find out.

If you want to pack that crossover back together with pieces of foam to protect the components inside and send it to me, I will document it. PM me accordingly.

THEN, if I were you, I'd reassemble it and sell both the crossovers and the tweeters, from which funds, I'd upgrade the Seville(s) (is it one, or a pair you have?) with modern horn tweeters and crossovers.

Yes, I have a design in mind, but I don't know Seville from a hole in the ground. I do know 414s are quite competent woofers, assuming that's what you have.

Here's the result of a recent non-Altec upgrade using the design I would propose:

attachment.php


I'm sensing a trend here. You don't like Santiago, and you don't like Seville. That's not intended as any measure of insult; perhaps it goes more to you becoming a discerning listener.... :yes:
Click to expand...

hmmm...so i guess the sevilles are odd balls. i've read some good things about them and thought that with crossover rebuild, improve hf/mf detail.
i will pm you.
 
O.K., I have the crossover, and have measured the components, but I can't come up with a schematic yet, because one of the wires from the inductor is broken free, and it's unclear where it goes. I came back to this thread to look at the pics to figure it out, but the Flickr pics say "This photo is currently unavailable" in post #1. Would you upload them to the AK server, please?

Also, where did each of the connecting wires connect?

I have red, black, yellow, white, green and brown.

There's a switch on the attenuation control. I believe it turns off attenuation completely when turned fully counter-clockwise, i.e., that's the max tweeter loudness position. Does that make sense to anyone? Boleros have a switch too?

On the tapped inductor, I would expect the inductances not to sum to the total, but the DCRs don't either. Any EEs here have some guidance?
 
sorry 'bout that. the wire came loose while loosening the tar. you're talking about the bare wire that's coming out of the inductor, right? it should be connected to the other end of the square oil cap.

yes, the attenuator had a switch and it turned off the tone control.

i had to delete the pictures from flickr.com due to limited set folder space, but i've uploaded them to the AK.
here you go...
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gogofast said:
sorry 'bout that. the wire came loose while loosening the tar. you're talking about the bare wire that's coming out of the inductor, right? it should be connected to the other end of the square oil cap.
Click to expand...
I'll be able to draw the schematic now. I'm trying other means to measure the inductor DCRs, which should tell us where the tap is.... :yes:
 
gogofast, that tar that came off so easily was probably black bee's wax. I cleaned an Altec N800F that was packed in the same stuff. Tar would not be that easy to remove.

And the problem with the HF in your Sevilles is probably the 3000G HF drivers. It is not a highly thought of Altec driver. In fact, I once read that it's diaphragm was actually a microphone dia, and it is not replaceable. I don't remember where I read that, but wouldn't be surprised if it is true. I feel you should follow Zilch's recomendation, and replace them with a modern unit. You will be astounded with the flat HF available today. And the 3000G's are probably still worth some money to a collector on E-Bay.
 
Attenuation control shown full CCW (max HF).

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gogofast said:
...niiiice!
you da man:thmbsp:
Click to expand...
I'm not real confident about the meaurements on the tapped inductor, but I measured three different ways and took the two that were closest.

What are the driver impedances?

I've posted a link on the Altec Forum. Hopefully someone who knows more will see it and either verify or correct what I have come up with.

I'll PM you about what to do now.... :thmbsp:
 
Zilch said:
I'm not real confident about the meaurements on the tapped inductor, but I measured three different ways and took the two that were closest.

What are the driver impedances?

I've posted a link on the Altec Forum. Hopefully someone who knows more will see it and either verify or correct what I have come up with.

I'll PM you about what to do now.... :thmbsp:
Click to expand...

414z is 16 ohms.
 
Great work Zilch
Looking at your schematic L1a & b form an autofomer. The primary current through L1a induces a voltage on L1b by the turns (N) ratio. In this case the HF driver sees Na+b/Na . A neat way to run a 16 Ohm driver with a 8 Ohm woofer.
Don
 
Thanks, Don. Autotransformers are common in vintage JBL crossovers; it seems they were a popular design approach among engineers at one time.

As used by JBL, they confer some immunity to impedance variation, as well.

I've never understood autotransformers, so I do my best to ignore them, probably to my detriment.

[Same with series crossovers. ;) ]
 
dlp4341 said:
Great work Zilch
Looking at your schematic L1a & b form an autofomer. The primary current through L1a induces a voltage on L1b by the turns (N) ratio. In this case the HF driver sees Na+b/Na . A neat way to run a 16 Ohm driver with a 8 Ohm woofer.
Don
Click to expand...

Could there be more to this than a simple autoformer??? By Zilch's measurements Na~Nb so the voltage step-up ratio ~ 2. Voltage x2 = impx2^2 or 32 ohm if 8 ohm LF imp is taken as ref.

I could be missing something. OTOH, after looking over many old Xover designs over the past year I'm beginning think there's a tendency to "misunderestimate" some of these vintage Xover designs/designers.
 
Not meaning to hijack the thread here- but my experience with the few Altec crossovers I have encountered suggests that their inductors tend to saturate fairly easy. I know when I A/B my Model 19's xovers between the upgrade type and the original the upgrade was much netter and saturation problems were avoided!

Altec typically builds very robust drivers I have found- particularly like their horn drivers and largeer 12"~15 (vintage) woofers. The relatively small inductors in the Model 19's suprized me. When I rebuilt the networks, with the Zilch upgraded ones, my power handling and definition improved substantially. The Erse super iton cores made a bug differance in the low end responce, as did the air core types for the upper end. Of course the new Erse poly caps helped a lot as well as did the new re-design.

So you should be in good hands here with Zilch (& others) on the case. I would think that anyone with these older larger Altecs, using the original networks, that upgrading them might be a viable consideration. After all technology does march on, and in the case of older xover components, sometimes for the better!
DC
 
Interesting thread. I'm waiting for some Solens now, to redo a pair of N800H crossovers, & wasn't sure what to expect from them. These weren't potted in anything, just mounted to a strip of iron channel, & the inductors are 2 different sizes. I haven't found ANY info on them, but that doesn't surprise me too much, as they're from 1202A Musical Instrument cabs (portable VOTT). I'll "probably" eventually bi-amp anyways, so maybe Zilch will want to have a gander sometime. :scratch2:
 
Nice old thread resurrected... Can this be used with 8ohm and is this crossover at 3000hz as is most Altec numbers relate, or is it just the model number?
 
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