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Multi-Way Conventional loudspeakers with crossovers

Box port or crossover dippity do
Box port or crossover dippity do
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Old 20th November 2019, 03:32 PM   #111
AllenB is offline AllenB  Australia
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It's moments like this that make a person feel they can get down to business. I mean, the first thing I noticed when I looked at these is what R2, R3 and C4 were doing
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Old 20th November 2019, 04:02 PM   #112
8ntractor is offline 8ntractor  Canada
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thank you Allen. As soon as I can and I get the meter. I will check out the components and clean up the pcb and the excessive solder and reinstall them R2 is still in but R3 and C4 have been removed. I will be out for the at least the next few days but I really appreciate your help
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Old 21st November 2019, 12:29 AM   #113
AllenB is offline AllenB  Australia
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Enjoy your time
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Old 21st November 2019, 01:50 AM   #114
8ntractor is offline 8ntractor  Canada
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I wish it were so - out of town eye surgery - a shiny new lens but with a follow up visit on Friday will be gone a couple of days. no lifting for a week. thank you again Allen.
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Old 24th November 2019, 02:13 PM   #115
8ntractor is offline 8ntractor  Canada
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I changed out r2 2.2ohm resistor for R3 12 ohm resistor the green line is before the change and the other two lines are raw and gated after the change.

the original r2 was a 20w mundorf supreme that looks like a tube and the new new r2 former r3 is a wirewound greenie. will that effect the sound or should it be a better resistor for some other reason? Will the larger resistor do other unexpected things to the crossover? there seems to be a more pronounced dip with the new resistor. I still have c4 and r3 out.
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Old 25th November 2019, 12:42 AM   #116
AllenB is offline AllenB  Australia
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Hi 8, it would seem you can see, excellent.

Choosing the right type of component can be very important in radio frequency applications, harsh/hot environments, power supplies, low noise applications and such. At audio frequencies with finite impedances we have more relaxed options.
Quote:
Will the larger resistor do other unexpected things to the crossover?
It will alter the damping of the high pass. I'm not implying this will be bad or good, but since it is different, and if it was working before...

An L-pad is one way to get attenuation without (too significantly) altering the load on the filter.
Quote:
there seems to be a more pronounced dip with the new resistor.
It can be difficult to extract surety through measurements that are not clean, but what you describe sounds like the result of a change in phase. You've changed the axial response by the shown amount, and the sound power by an uncertain (but could be measured) amount.
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Old 25th November 2019, 01:59 AM   #117
8ntractor is offline 8ntractor  Canada
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Hi Allen thank you,

the eye surgery was downright weird they keep you awake while they put the new lens in. I can see almost as well as before the surgery and they say it will get better over the next month. Still no lifting 10lb limit.

when you say the damping of the high pass do you mean lowering the FR of the tweeter?
I was thinking about the L-pad but when I enter it in xsim it looks like the 12 ohm resister in parallel raises the FR, so a much smaller resistor may be the ticket. returning the 2.2ohm to R2 and a smaller resistor (1ohm) to R3. that may have less effect on the load than the big resistor in R2? the capacitor seems to raise the mid treble with the larger resistor and negate the smaller resistor so that may not be the best thing unless it is there for other reasons. Because shipping is generally expensive I would like to get a list of components rather than order a few at a time. I will buy the better resistors when I do order.


I am confused about phase and polarity. the crossover schematic calls out normal polarity but I have always had to invert the tweeter even with the thors. I have read a few articles on and will continue to do some homework on it.


Quote:
You've changed the axial response by the shown amount,
is that why the imaging outside of the speakers has changed? I was thinking the dips may be from the cheaper resistor.

The measurement errors are troublesome but seem more consistent without bit perfect in the background. overall the speakers sound pretty good I think there is still more potential there. Thanks again Allen sorry for the long post.
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Old 25th November 2019, 06:05 AM   #118
AllenB is offline AllenB  Australia
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By damping, I mean the load on the high pass components can change the levels especially around the knee of the cutoff. Certainly not likely to happen evenly across the treble.

Don't read too much into what the polarity is. It is chosen due to other aspects of the cross.

When I said the response had changed, I didn't mean the drastic dips.. I'm choosing to ignore those. I was assuming you were too when you said you saw a change. This certainly is not the kind of change you'd see from changing a resistor in a crossover. The kind of change I'd expect to see with regards to phase changes, which would affect the driver's interaction with each other, would be a gentle undulation around the crossover region of a couple of octaves or so and within a couple of dB for a small change. Anyway, if you can see any consistency between these dips, then they could be dealt with. Which reminds me, some have success using ASIO drivers.

The L-pad parallel resistor should normally bring the level down, not raise it.

Last edited by AllenB; 25th November 2019 at 06:09 AM.
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Old 25th November 2019, 08:05 PM   #119
8ntractor is offline 8ntractor  Canada
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thank you Allen So I changed the crossover and put the better 2.2r resistor back in to R2 and the 2.2 cap back in C4. I am reading about crossovers and realize that just putting the 12 ohm resistor in even though it sounds better is not necessarily the correct thing to do.
Quote:
Ah yes, R3/C4 cut in around 6k to make sure that R2 can continue attenuating through the higher frequencies despite the rising impedance.
I would like to purchase the components to lower the FR for the tweeter and carry the attenuation out to 20k. so if I understand correctly R2 should be larger as demonstrated by the speakers sounding better with the 12 ohm resistor maybe around 5.1 ohm would lower the FR about 4-6db and reducing f3 to 2.2 ohms. it does raise the impedance from 6 to 9 at 20k. I am not sure about the capacitor if or what to change it to. there is a rising slope from around the crossover to 20k of about 4-6 db. is it possible that the rising slope is because the tweeter is inverted and the woofer being out of phase is lowering the low treble?

interestingly I ran the best charts from the Thors before the woofer change and the same issues show up when gated. in fact the current speakers look a little better. attached is a copy of the current chart and the best Thor chart gated.
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Last edited by 8ntractor; 25th November 2019 at 08:30 PM.
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Old 26th November 2019, 01:29 AM   #120
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by 8ntractor View Post
it does raise the impedance from 6 to 9 at 20k.
Decreasing the parallel resistor (R3) at the same time as increasing R2, keeps it in line. If you are going to increase R2 much, it might be better to eliminate C4 to reduce the load at the high pass filter.

Pretty soon all this is going to throw the blending off at the crossover. You'll want to keep track of phase changes.

Quote:
is it possible that the rising slope is because the tweeter is inverted and the woofer being out of phase is lowering the low treble?
Even with the polarity reversed that way, they shouldn't have been out of phase originally. Phase does roll around, changing polarity can be used to keep up with that.
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