Model 19 crossover caps

[Valveboy]

Hi folks,
I've seen similar posts to this, but not really any definitive answers... Is there a source for the non-polar caps in the 19 crossover? One of the pair I'm rebuilding has two of the four caps blown. There was an obvious meltdown in the 8mf and 21mf caps, brown goo on the ends of each. (Yes, GPA has the drivers for rebuild, they were fried). Resistors and coils appear to be ok, just the caps.
Thanks
Dave

[dgwojo]

I'm rebuilding a pair of N1209-8A crossovers right now, I bought all my Solen Caps from Madisound, and Parts Express, they're 5% tolerence versus the stock 20% used back then. If you need an unlisted value, just wire a combination of them in parallell and add the values together, like three 7mfd ones together for 21mfd, it's best when using multiples to use similar values. Dave.
http://www.madisound.com/chateauroux.html
http://www.partsexpress.com/webpage....&WebPage_ID=71

[dgwojo]

I compared my N1201-8A crossover to the N1209-8A, the internal caps and resistors are different, I don't know about the three coils, I don't have a way to measure inductance. I'll also open up a Model 19 crossover this week to compare it to the N1201-8A, I think those should be the same. The N1209-8A contains two 2 ohm resistors, two 8 ohm resistors, two 18mfd caps, one 6mfd cap, one 10mfd cap, three coils, and two L-Pads with only two legs off each used. More later this week, Dave.

[armandh]

caps age and rather badly. any that are over 10 years old are questionable. unless you have a meter you may not have what the circuit calls for.
catastrophic failure on very old lytics not that unusual. just change them all. no less often than a tube amp of similar vintage.

[armandh]

ps Ive never seen an air coil inductor change.
want to learn more?
http://web.mit.edu/smcs/8.02/

[Earl K]

Hi

Those Model 19 crossovers used two types of caps to my knowledge.

The "Callins" type and the other type that was really only identified by the "AC" moniker ( usually followed by 3 lines of other info ).

I have a box of these "AC" caps that are of larger values than the caps in the 1201 or 1209 crossover.

Out of curiousity late last fall I cracked one open. Visually, to my eyes its a straight ahead "paper in oil" cap . I found a central plug of tightly rolled brown kraft paper that was mildly damp. These things are made as a tube within a tube. ( The paper roll was inside the inner tube.) Then gobs of that pinkish red plasitc is used as a single hermitical seal that plugs the ends of the inner and outer tubes. My caps are in the process of drying out & somewhat oxidizing as something in the oil reacts with the trapped air .

These caps have fairly audible resonances to the trained ear .

This is all quite long winded - but I would certainly encourage anyone with these types of caps to change out them out . I'd start by trying out / listening to a similar sort of dielectric. ( PIO )

I also have a Callins here that I haven't yet broken open - so I can't tell you it's dielectric type.

I use quite heavily bypassed MPP in oil on my 288s. The bypass caps are all Dry Film MPP or KP types. ( MPP = MetallizedPolypropylene. KP = Film & Foil Polypropylene )
The "oilers" makes quite a difference in the quality of audible circuit damping . They are extremely generous to the lower mids while somewhat suppressing the higher mids ( happily that's an FR area where just about all the dry film types excel in their own particular signature of transient release ) .

<. Earl K

[zelgall]

I rebuilt my 19 Xovers last week because when I lifted one end of the caps to measure the values I found they were way out of spec. eg the 21mF's were 25 and 17mF the 6's were both under 5. So out they all went and I replaced them with some rel caps, wonders and some vintage oils. Sound is much better, clearer with better dynamics. I'm not sure how much is the type of caps and how much is having crossover values correct to the original. I didn't change the resistors or the coils as they measured OK.

[RonSSS]

Excellent info Earl. Thanks.
I'm looking at a model 19 xover right now, and indeed...Callins and AC caps.
I would really like to hear from others who have tried high end caps in these or other Altec Crossovers. Jeff Markwart has done great work here, and has some reccomendations. There have to be other caps that work well.
I changed the caps on my Duplex's to some I bought from North Creek Audio. They were called "ZEN" caps, and to be honest, they were painful. They said to let them break in....they were painful. They also said they could be wired in the other direction for a mellower sound????
Anyway, the point I'm trying to make is that I think horns are really revealing, and the caps will have a great effect on what you hear.
Coils:
I didn't try different coils. Too much money for the flat wound coils. But how about simple wirewound air coils? We can make those ourselves.....
Anyway,
Ron

[sburke]

I'll pipe up here. I posted this over on AA sometime back. I built external crossovers for my Model 19's using ASC motor run caps, Mills resistors, and Goertz inductors. Pretty much the same values as the existing crossover. The crossovers turned out very good IMO. They didn't change the Altec sound and tightened up the bass and provided more clarity in the upper frequencies. I made the crossovers so I would have the ability to bi-amp and separated the circuit between the drivers. In addition, I rewired the internal drivers and added binding posts to the back of the cabinets. A pair for each driver. I've attached a pic. You can compare the size of the new crossover with my foot off to the right.

[RonSSS]

Nice work! I love the non-inductive pegboard! Good idea.
How much were the inductors?
And where did you buy them?
Ron