Tweeter resistors

[Serratoga]

Hi everyone,

I have a 1.5 ohm Caddack (MKP 930) resistor on my tweeter at this moment.
I hear that having more than one resistor helps the roll off on the tweeter.
If I parallel 2 of the 3 ohm caddocks it will give me 1.5 ohm as well. can anyone
make more sence of this or is it just myth?

Thanks

[Tube_Dude]

Originally posted by Serratoga
is it just myth?

[Cal Weldon]

Using two of the 3 ohm in parallel gives you 1.5 ohms. It will sound virtually the same as one at 1.5 ohm. You would use the parallel resitors if you need higher power handling.

What do you mean by rolling off?

Decreasing the overall output or tapering the frequency at the high end?

[Serratoga]

Cal, I always thought using more than one resistor to reach a same value caused the Q to lower?So the tweeter has a less sharp roll-off at the crossover frequency. I could be mistaken? and understood it wrong.

[Cal Weldon]

I think we need someone else to pipe in here. I'm not sure about the Q changing.

[bear]

Especially in the case of a Caddock, no difference in the HF response.

What will change ever so slightly is the effective diameter of the wire that connects to the tweeter... will that matter in the sound? Perhaps.

In the case of say a "sand cast" wire wound, the total self inductance of the two will be reduced, but that effect is WAY out of the audioband.

Try running ur tweeters with thin wire and then with THICK wire, and see if you hear any differences. Try measuring the difference in the nearfield with a fixed mic set up and test levels.

Report back.

_-_-bear

[ocool_15]

I'm pretty sure you got something wrong there. If you used wirewound resistors with noticable inductance you may be able to get it to appear more like an ideal resistor by using several in parallel. But for the price you could easily buy a decent resistor.

When parralleling multiple caps you can reduce the ESR(series resistance) of the capacitance value. I think that is the most likely cause of your confusion.

[Serratoga]

I see where I went wrong.

I am using a 1.5 Ohm resistor at the moment in series on the crossover, but if I use a L-pad
design, one in series and the other in parallel thats when the Q lowers and that lowers the high-pass crossover frequency fractionally. Using a 2 ohm and a 7 ohm gives you 1.555 ohm.

[Geoff H]

Serratoga, I think you still have a misunderstanding. Q is a ratio of reactance (either capacitive or inductive) in ohms to resistance in ohms. It does not matter how the resistance is derived, series or parallel combinations.

Energy sent to reactive components is stored momentarily, then dissipated into resistance. Ideally this is the acoustic resistance between the cone and air.

A low parallel resistance across the tweeter will reduce it's Q, and may be of a benefit if the crossover F is too low. Again, whether that resistance is obtained from 1 resistor or several is non relevant. It's the total resistance that counts.

HTH,

Geoff

[audiobomber]

Serratoga, you may get somewhere faster by stating what it is you're trying to achieve. Is the tweeter level a problem? What does the circuit look like?