KLH Model 30 Crossover Help

[dodog]

I was out at a city-wide garage sale this weekend and came across a pair of KLH Model 30's, with badges (no matching TT/stereo though), for $2. How could I pass them up? I've had 23's and currently have 5's in my upstairs system. I'm planning on fixing these up (cabs are in amazing condition) and giving them to a friend. However, the caps need to be replaced. I measured the resistors and, other than looking old, they measure spot-on. No worries there. What do I have here?

Note: back side of crossover is just flipped (black cap on far right)

Yes, the pictures are blurry. Is the silver cap a PIO or is it just a cheap electrolytic? From what I can read:

silver cap: 8 MFD 50 VNP (8 uF, 50V?)
black cap: 2x2 UF 50 VNP (two 2 uF, 50V?)

KLH sure liked to use strange dual-caps. Reminds me of a 2x4 uF that was in my 5's (http://www.audiokarma.org/forums/showthread.php?t=424932&highlight=crossover). Given the layout of the board and the traces, can I just substitute two 2 uF caps (there are two holes per each trace on top, the bottom four holes are all connected to the same trace), making sure to keep them separate to their respective pads? Something like this?

 

[Naptown Rob]

Yep. I do believe you've got that right.

 

[Watthour]

No inductors?

 

[Boto]

I'm curious about the black cap. I had a similar one in my KLH 24. It was actually a dual tap capacitor: it has an 8uf and a 16uf output on it. It may have another line of information below the one you can see.

 

[dodog]

I can snip the leads and take a look tonight. I'm pretty sure it's a 2x 2 uF cap if it's anything like what they did in the 5's. However, it is worth investigating.

 

[dodog]

No inductors?

It could be like the 23's and have the inductor mounted off-board elsewhere in the cab. I was in a bit of a hurry and didn't feel like digging too much through the fiberglass to look around (itchy itchy). Dunno.

 

[dodog]

I'm curious about the black cap. I had a similar one in my KLH 24. It was actually a dual tap capacitor: it has an 8uf and a 16uf output on it. It may have another line of information below the one you can see.

So, I snipped the leads and hooked the caps up to my meter.

Silver cap

Should be 8.0 uF, measured at 11.7 uF (~47% off of spec.)

Black cap

I *think* these should be two 2 uF caps in one package. With the following:

I'm making the assumption that A1 and A2 are two separate caps. If so, Measuring 1 to 2 should result in the two caps being in series.

A1:

Should be 2 uF, measured at 3.57 uF (~78% off of spec.)

A2:

Should be 2 uF, measured at 3.88 uF (~94% off of spec.)

And, for the final test. If these are in series then:

1/x = 1/A1 + 1/A2
1/x = 1/3.57 + 1/3.88
x = 1/(1/3.57 + 1/3.88)
x~= 1.86 uF

When I measured from 1 to 2 I got 1.89 uF. With rounding and all that, I think I'm solid.

I planned a recap anyway but now I have proof that these caps are old and shot (not surprising given their age).

Unless there is a major flaw in my logic, I'll proceed by getting two 2 uF caps and one 8 uF cap per crossover. Thanks for playing along!

 

[dodog]

I hadn't seen specialidiot's thread on his 17's. Looks like the same issue (2 x 2 uF):

Different package than my Temple cap but same result. Other than the L-pad, looks to be the same crossover as well. 8 uF to woofer, 2 x 2 uF to tweeter (even the same resistors). Seems to make sense since given how they used the same tweeters and woofers in various models:

http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=5808