Altec 32343 Network Divider

[Corona Blue]

Hello Altec Users!

First post here. I came across your forum while searching for info on the Altec 32343 speaker cross-over.

Some time ago, I purchase from a friend a set of home-built PA speakers. Loaded with a 12 inch JBL woofer and plastic rectangular horn. I never used them until recently when I hooked them up to a small stereo system in my workshop. They are a compact speaker, dimensionally resembling something like the 9849, but with a full 1 inch vent gap across the bottom of the entire baffle board. They use the 32343 Network Divider with the HF compensation and 1/4" phone plug input.

They sounded just "ok." Nothing great. One of them sounded a bit different than the other, and the compensation resistors seemed like they were both dirty, needing some cleaning. So I pulled out the 32343 boxes and noticed that one of the caps in one unit was leaking and the same cap in the other unit was completely blown! There was paper everywhere. And I could see that someone had done some messing around in there... bad soldering. I figured that I would just buy some quality caps and go through both units. But then it occurred to me that maybe whoever was in there may have changed something, and I was hoping to get a good schematic to verify that things are right and to get the cap values. Does anybody here have that schematic? Also, thought I would ask if you guys have a preferred type/brand of cap to use in these?

I will post some pics of one of the units tomorrow night.

Thanks in advance,

Allen

[tomt]

i prefer oil caps.

i have no schematic .









37

[Corona Blue]

Ok... here are some pics... sorry, a bit blurry...

It turns out the woofers are JBL 123A-1 (8 ohm)




I don't know about the horn. I found no markings on it. The black rear cover is cast aluminum and the horn is plastic.





I don't know if the cabinet is home-made or if it is an Altec Lansing design. (Ed: Now I think it is DIY). It is made from 3/4 inch birch ply and its outside dimensions are: 24" (H) x 16.5" (W) x 12" (D). It doesn't have a lot of physical depth, as though it was designed around JBL 123A-1 which has a shallow basket.





In both of the 32343 cross-overs, the black plastic caps were leaking, and in one of the cross-overs, one of the 18uf caps fully exploded. I'm sure this happened before I bought these and it's probably why I got them so cheap. Cap values are: 3uf/75V; 6uf/100V; 8uf/75V; 18uf/50V.





So I was looking at replacing the old caps with Solens, since there is not a lot of room inside the control box and they are not too expensive. I've never used them though so I don't know what to expect. The old caps (marked "TSI") do appear to be a PIO cap, judging by all the paper shrapnel plastered over everything. If you guys have any suggestions on better caps, please feel free to chime in.

Thanks again,

Allen

P.S. still would like the schematic if anybody has it. thnx.

[Earl K]

Hi Allen,



- If you click on the above image you'll see the complete collection of ( Lansing Heritages ) 1975 Altec reference charts .

- The last page of those charts, has 3 references to the network model which you have .

- That network # ( 32343 ) was installed in the 9849 ( series ) of speakers.

- The stock 9849-8B has different dimensions from what you've posted / maybe yours was the original design or maybe it's a custom build .

- FYI, 9849s are supposed to have 414 woofers in them / not a JBL and certainly not the JBL 123A-1 model .

- I've scoured the forums and can't find a schematic of this crossover for you / apparently no one has yet committed it to paper .

- Bowtie427 has a pair of these and has made numerous mention of the network having some built-in HF compensation (IE; midrange suppression ) .

- From the capacitor parts ( quantity & the values which you've mentioned ), it appears that the network could have a Zobel in the LF area of the network ( most likely the 18uF cap, if it's wired in series with an @ 7.5R resistor / then strapped across the networks' woofer output ). The 3uF & 6uF caps should belong within the HF portion of the network with either the 6uF cap ( or the 3uF ) spanning ( ie; bypassing ) the typical Altec "T-Pad" & therefore engaging the mentioned HF compensation .

<> EarlK

ps ; What resistor values to you see ?

[Corona Blue]

Hi Earl K-

Thanks for the link and for looking around for the schematic. I looked before I posted. I must commend you guys for having such a nice library of documents!! Very handy!

The resistors I saw all looked like 10w ceramics... going from memory here... 2 x 5ohm in series and an 8ohm. I will verify how they are wired.

I'm just wondering if it might be worth changing out the ceramic resistors for non-inductive 25w (finned aluminum) resistors that I can bolt to the box for extra cooling. These would have the additional benefit of being much smaller than the huge ceramics.

The 18uf cap that exploded was installed right up against one of those ceramic resistors. I can't imagine the heat would have done it any good. I have no idea how long it was like that. I have not used these speakers much since I have had them.

I was hoping to have a look at a schematic of the network to verify if it has been altered. Just wanted to know. If I get a free hour, I will attempt to derive it for the group.

Best,

Allen

[voice of the theater]

Allen--I saw your photos regarding this thread over at L.H. and am posting the link here since you mentioned you'd be posting the photos here eventually. This may help you to get some more info from our members.
http://www.audioheritage.org/vbullet...What-are-these Your H.F. drivers look very similar to Altec 802-8G drivers and the cabinets look to be home-made, but there are most likely other members here who can be more specific/add to these observations.

By the way, I have used the Solen caps (that you mentioned) in my Model 19's and Model 14's and have found them to have excellent sonic characteristics. However, everyone has their own preferences in caps and I have seen threads regarding capacitor preferences generate almost as "spirited" of a debate as threads regarding wire/cables. Best of luck with your project....

[Corona Blue]

Hi V.O.T.-

Thanks for the cross-link over to L.H., and for the info on the Solens. I went ahead and purchased a set for both networks and I'm sure they will be more than adequate. They would have to be better than the old dried up caps that were in there!!

I tend to prefer paper in oil caps or good quality foil in oil, but with the space limitations on this network box, and the cost of oil caps... HA! The caps would be worth more than the rest of the components combined!

With regard to the HF drivers, I too thought they looked a lot like something that might have come in an old Altec. They actually sound very good whatever they are. Great dispersion pattern and wide "sweet spot." The 123A-1's seem to lack punch. I have no experience with them beyond this project, so I don't know their innate character. Do people ever modify these? Or is that considered sacrosanct amongst the vintage JBL fans? Just curious. I'll re-evaluate them after the XO networks are finished.

Well I hope to have some time to draw up the 32343 schematic. When I do I will post at both forums.

Thanks again for the assistance,

Allen

[RonSSS]

The caps you have there are original. All altec crossovers from that era used those black caps with red ends. So I don't think anyone had changed values. I'm betting the blowed up one is the shunt cap that goes across the woofer. Which means someone really cranked the volume!

I don't think you would gain anything by replacing the resistors. They certainly shouldn't be getting hot.

Is that JBL woofer some sort of high powered deal? If someone had these up loud enough to pop that cap, I wonder how the hf fram survived?

I have a pair of the 9849's and I hate to adnit that I've never listened to them......

Ron

Hi Earl K-

Thanks for the link and for looking around for the schematic. I looked before I posted. I must commend you guys for having such a nice library of documents!! Very handy!

The resistors I saw all looked like 10w ceramics... going from memory here... 2 x 5ohm in series and an 8ohm. I will verify how they are wired.

I'm just wondering if it might be worth changing out the ceramic resistors for non-inductive 25w (finned aluminum) resistors that I can bolt to the box for extra cooling. These would have the additional benefit of being much smaller than the huge ceramics.

The 18uf cap that exploded was installed right up against one of those ceramic resistors. I can't imagine the heat would have done it any good. I have no idea how long it was like that. I have not used these speakers much since I have had them.

I was hoping to have a look at a schematic of the network to verify if it has been altered. Just wanted to know. If I get a free hour, I will attempt to derive it for the group.

Best,

Allen

[Corona Blue]

I had a minute to revise the schematic of the Divider Network... just some clean up really. I wanted to show the logical correlation between the Zobel filter in the LF and the LR filter in the HF sections. And I added in the extrapolated inductor values as provided by Earl K. If you have additions or corrections, please advise, and I will do so.





I will re-post on Wednesday with some measurements of the horn driver. One question: If I choose to remove the rear cap, do I need to be careful about anything in particular? What to I need to be wary of?

Thanks!

Allen