Resistor confusion

[Richard Dyszel]

Hi, I'm replacing the crossover components in a pair of Design Acoustic D-6 speakers. I've finished the first one and began working on the second one and noticed that in spite of using the same model drivers at there is one difference in resistors.

In one cabinet the positive input goes to a 5 ohm resistor followed by a 33mfd capacitor before going to positive input to the mid-range driver. In the other cabinet there is a 10 ohm resistor in the same circuit.

I don't know why they are different, I don't know which is correct and I have no idea what difference it makes. Can any one help me with the mystery?

 

[slipperybidness]

Is there a reason that you are replacing the X-over components?

And, 33mfd??? Is that "milli" or "micro"

 

[Richard Dyszel]

The speakers are over 35 years old and the woofers need new foam. I figured that while I was in the cabinets, I would refresh the components too.

Based on what I've read the 33mfd is micro Farad.

the one cabinet that I've finished sounds fine with the new components and the re-foamed woofer.

 

[Swerd]

Unless resistors are visibly melted or burnt, they don't go bad with time. If you don't have schematic of the original crossover, I'd say leave the old resistor as is.

The alternative is to try it both ways, with a 5 ohm and with a 10 ohm resistor. They aren't expensive.

 

[Richard Dyszel]

I guess I'm curious as to why supposedly two identical model speaker cabinets have one different resistor in the crossover. But since I can't seem to get the original schematic I'm stuck with second guessing.

That being said, what difference would going from 5 to 10 ohms on a resistor have in terms of the sound of the mid-range driver? From what I've read, resistors are in a cross over to lower the signal strength to a particular driver to help balance it in relationship to the other speakers. Is that correct?

If so then having a higher ohm resistor would lower the sound level of the speaker it was connected to?

 

[markw]

Apparantly, they sounded fine until you got into this project. I'd say you didn't even notice any difference. All the speculation in the world won't answer your question as to why they did what they did

Try it both ways and see how you like it. If you can't tell the difference, I wouldn't worry about it.

 

[TLS Guy]

I guess I'm curious as to why supposedly two identical model speaker cabinets have one different resistor in the crossover. But since I can't seem to get the original schematic I'm stuck with second guessing.

That being said, what difference would going from 5 to 10 ohms on a resistor have in terms of the sound of the mid-range driver? From what I've read, resistors are in a cross over to lower the signal strength to a particular driver to help balance it in relationship to the other speakers. Is that correct?

If so then having a higher ohm resistor would lower the sound level of the speaker it was connected to?

It sounds like the band pass gain resistor. They can't both be right, so one is wrong. The difference will be 3db output on the midrange.

I suspect the 5 ohm resistor is correct, but that is a very soft guess. The best thing will be to set both speakers the same and try the 5 and the 10 and see which you like best. You should easily tell the difference.

 

[TLS Guy]

On second thoughts, you probably won't tell much difference.

That looks like a design best forgotten. It is beyond hope!

They likely threw those together from whatever was in the parts bin.

 

[slipperybidness]

They likely threw those together from whatever was in the parts bin.

I've never seen anything like that! I think you nailed it.

Is this the precursor to White Van?

 

[Swerd]

I guess I'm curious as to why supposedly two identical model speaker cabinets have one different resistor in the crossover.

Perhaps the mid range drivers varied in their output from unit to unit. That's only a guess.

From what I've read, resistors are in a cross over to lower the signal strength to a particular driver to help balance it in relationship to the other speakers. Is that correct?

Yes

I've never seen anything like this design. On the protruding flat part of the front baffle are 2 drivers, a mid range and a coned tweeter, about 2" in diameter. On the beveled sides are what look like 4 more tweeters. I can only guess that they were added to increase the limited dispersion of the "main" tweeter.

Why the woofer is on the back side is another puzzle.

Without a crossover schematic I won't even try to guess how these various drivers were intended to work together.