Anyone know what the attenuation is for a CW2 crossover?

[m00n]

Ready to put together my CW2 crossovers, can someone tell me what the attenuation is for the CW2 with the following:

K-79
K-57
K-33 (Bob Crites version)

[boom3]

If you are using the stock network, or an updated clone, look at the schematic and see the taps taken off autotransformer, that's the attenuation for the mid and tweet. I'm not sure what the attenuation is in dB, I'd like to know myself. The relationship between the taps and dB of attenutaion has been posted here, maybe a search will find it. It may be easier just to Ask Bob, I'm sure he knows off the top of his head. []

[BEC]

I am afraid that is one I don't know. I could measure it if I had a Cornwall II crossover, but don't have one of those. The Cornwall II doesn't use the T2A autotransformer. The one it used is the 3507 according to the schematic I have.

Bob Crites

[Deang]

The K-79 is 3dB less sensitive than the K-77 -- so roughly 102dB/w. I haven't looked at the schematic in some time, and not until Bob mentioned it on the phone today was I fully aware that the tweeter is run full out without any attenuation from the autoformer. So at this point, we know we have a 98dB woofer and a 102dB tweeter. I don't think Bob will agree here, but the tweeter filter is similiar to the AA, and I have feeling that if we measured that tweeter with a microphone, we might see a tweeter putting out closer to 99-100dB/w. That brings us to the midrange. No T2A, so -- we can safely assume the attenuation level is not -6, but either -5 or -7. I would go with -5dB.

[m00n]

So dean according to Bob's chart

Input Taps |

Output Taps |

Attenuation(DB)

0-X

0-4

1

0-Y

0-4

2

0-5

0-4

3

0-X

0-3

4

0-Y

0-3

5

...

...

...

...

...

...

I will set the transformer as such:
Input would be Post 0(Neg), Post Y(pos)
Output would be Post 0(neg), Post 3(pos)

Is that correct?

[BEC]

moon,

5 db is a good place for a trial. Not just to be different from Dean, but for other reasons, I am going to guess that the attenuation should be 7 db. Yes, you are right on the connection for 5 db.

Bob

[m00n]

Should I cut you guys in the middle and go for 6?

[BEC]

No, we both agree that it should not be 3, 6, 9, or 12 db. We can just eliminate those right off the top.

Bob

[m00n]

Ok great.

You know, I feel like the village idiot, here I am trying to build my own crossovers and I don't even know what attenuation is.

[BEC]

moon,

This is not really tough. We are just trying to match up the output of the three drivers in the Cornwall II cabinets. In general the squawker is the loudest (most sensitive) driver in the cabinet and the woofer is the least sensitive. To sound right, we have to at least attenuate (drop down the output) of the squawker some number of dBs to match the other drivers. In some cases we drop the level of both the tweeter and the squawker, but it seems with the Cornwall II that only the squawker is attenuated. We are just trying now to reason out how much to attenuate it since Klipsch hasn't told us that value on the schematic.

If you look at this schematic for the Heresy II, you will see that Klipsch was nice enough to tell us that number right on the schematic. -10 dB.

Bob

[Deang]

"Attenuation" -- just means you're bringing the output level down.

You're probably right Bob. If the K-57 has the same sensitivity as the K-55, and the AK-3 network is -4, then it makes sense for the CII to be -7. Is that one of the things you were thinking?

EDIT: That -10dB on the HII is another good argument for the CII being -7dB.

[BEC]

"Attenuation" -- just means you're bringing the output level down.

You're probably right Bob. If the K-57 has the same sensitivity as the K-55, and the AK-3 network is -4, then it makes sense for the CII to be -7. Is that one of the things you were thinking? 

No, look at the H2 schematic I just posted and consider things that it tells us. The mids and tweets are very similiar between the H2 and C2.

Bob

[m00n]

Thanks Bob and Dean. I'll set it to 7 then. [H]

[BEC]

moon,

Remember, we are just guessing and figuring. You may have to end up trying a couple of settings and doing some listening to get it right. Or perhaps someone will eventually chime in with the specified value. I sure wish now that I had measured one when I had a CII crossover here for a rebuild.

Bob

[m00n]

Ok, one more dumb question regarding caps and inductors.

Does it matter which way a cap and inductor is hooked up on the circuit? If memory serves me correct, it does not.

Thanks
Rick

[BEC]

No, makes no difference.

Bob

[m00n]

Does my xover layout look ok? Nothing too close? One thing to note, the black wire strip was not screwed on and shifted just as I took the picture, so it's not sitting correctly in place.

Also, all my wires will be underneath the board once i start to solder this together.

Which leads me to yet another question. (imagine that)

I'm going to assume that I can trip the cap leads, but what about the inductors? Can I trip those leads or will it affect their values?