Cornwall crossover advice

[jbek]

I've got a question for you more technical types out there...

I need to put together a pair of Cornwall Type B crossovers on a budget... I've successfully built a set of Al's crossovers for my Khorns and I don't have the money right now for all those expensive parts...

I do however have my spare AA networks and I was wondering if these could temporarily be turned into Cornwall type B networks till I get the dough to go with the better ALK's??

I have a photo of the type b networks and it looks like they might use the same T2A, 2uf caps, and the 2133 inductor (is that what that is?)... I just don't have an example to make the right connections. As you can see, I'm no electrical engineer... I know just enough to ask the right questions and ensure I don't screw up... I could probably decipher a schematic with a question or two... Can anybody point me in the right direction?

Any assistance would be greatly appreciated!

[Al Klappenberger]

Jbek,

The answer is YES!

1-remove the zener diodes.

2-In the tweeter filter: remove the .45 uH inductor and output 2 uf Cap.

3-change the big 13 uF cap to a 4 Uf

4-move the squawker lead from 4 on the transformer down to 3.

5-move the remaining 2 uf cap from 5 on the transformer down to tap 4

That should do it.

Al K.

[jbek]

Wow Al! That was quick.

Couple of questions:

1. Are the zener diodes the 2 diode looking things sitting in an L shaped bracket with both wires soldered to terminals 8 & 7 (the tweeter terminals)?

2. I'm confused about #2...

a. Is the .45 inductor the circular item with the screw in the top of the black plastic top? Are you saying to desolder the black lead from that goes to the 2uf cap and the black lead going to terminal 7?

b. When you say "remove... output 2 uf cap", what do you mean? Do I leave the connection to the other 2 uf cap and the one going to terminal 8 connected?

c. In my photo of the Type B, that last connection looks like it is soldered to terminal 3 of the T2A...

3. No problem on the 13 uf to the 4 uf... do you recommend anything in particular... since this will be temporary, I'm not sure I want to invest too much (e.g., Solen)... Oh yeah, in the photo of the type B crossover, I only see 2 caps... are they not the same 2 uf caps that are in the AA? Why would I need an additional 4 uf cap?

4. Gotcha!

5. Gotcha!

Thanks again Al! Just want to get things clear!!

Oh yeah, one last thing.. Besides the 301 Tractrix mod, any ideas on a K-600 replacement?? I need to find a pair...

[Al Klappenberger]

Jbek,

1 - Yes, you have the zener diodes identified correctly. You only need to

disconnect one of the two wires from them.

2 - The tweeter filter in the "AA" cosists of a series 2 uF cap, an inductor

to ground and another series cap at the output to the tweeter. The objective

is to reduce this to a single 2 uF cap in sereis. That means "open" the

inductor and "short" the output 2 uF cap. This is the same as removing them

from the circuit.

a - Yes, the .45 mHy inductor is the small round thing mounted with a screw

down through the middle of it. If you take out the screw you will see that

it is actually nearly square. It's just held down by a round plactic washer.

b - You "remove" the 2 uF output cap by short in out or replacing it with a

wire.

c - The squawker is to be connected directly to tap #3 of the transformer.

3 - The big 13 uF cap on the "AA" becomes 4 uF because the load presented to

it by the squawker changes when the transformer taps are changed. It also

has to roll of the squawker at a different frequency. This cap sets the

lower frequency limit to the squawker. The Cornwall needs 4 uF rather then

13. I would used any capacitor you can get other then an electrolytic.

Al K.

[jbek]

Okay. I think I've got it.

Just one last thing -

When you say "short" the 2uf cap, you mean the one next to the .45 inductor... and when you say "short", you mean connect the 2 terminals on top of the cap together...

This would be the equivalent of taking the cap completely out of circuit and connecting the leftover output of the other 2uf cap directly to terminal 8. Correct?

Any ideas on a replacement for the K-600 without making changes to the cabinets?

Thanks a whole bunch for all the assistance AL !!

This allows me to get a pair of old CW's up and running w/o spending any dough! A must for a laid off guy like me...

[jbek]

Oh yeah...

Could I use the 4.3uf Solen you require in your crossover plans as my temporary 4.0uf cap and then reuse that when I'm ready to go to the upgrade??

Thanks again!

[edwardre]

Cool! My '83 CW's have the B-3. I've an extra set of AA's that will now be converted to CW B's.

Thanks JBEK for asking the question. Thanks Al for the answers!

------------------

Ed

[Colin]

Can I bi-amp the B2 crossovers? If not, what do I need to bi-amp the Cornwall crossovers?

------------------

Colin's Music System Cornwall 1s & Klipsch subs; lights out & tubes glowing!

[mike stehr]

Well,

You would have to separate the woofer circuit

on the passive crossover from the midrange and

tweeter circuit.

or the tweeter circuit from the midrange

and woofer circuit, though the first approach

would be probably be a better way, due to the mid and

tweet being horns.

You could reconfigure the terminal block

on the crossover for input for the bass amp

and another input for the mid/tweet amp.

It may require another terminal block.

You could use a active crossover in a 3 way

setup and bypass the passive network altogether.

This would require three amps, though.

It could be done with two amps, but still use

the passive network for the mid/tweet section,

either straight off the amp or a high low pass

configuration on the active.

Or you could leave the passive network alone.

What are shootin' for here Colin,

tubes on the mid/tweet section, SS on the bass

section?

THANX!