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-   -   Introduction to designing crossovers without measurement (https://www.diyaudio.com/forums/multi-way/189847-introduction-designing-crossovers-measurement.html)

Richard10 2nd September 2019 03:39 PM

Thanks for the quick reply. I've thought of a supplementary question. Would I be right in saying that the shunt capacitor affects the roll-off of the bass driver in a different way to the series inductor? By this I mean that with an increase in the inductor value the sound can end up a bit muddy and dull, whereas increasing the capacitance seems to have more effect on the upper midrange nearer the crossover.

AllenB 3rd September 2019 01:22 AM

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I'd agree with that. Increasing inductance reduces the filter Q (changes the response vs frequency around the filter knee), and increasing capacitance increases it. This is the same for the tweeter circuit despite the fact that the C and L are in different locations there.

This image shows response vs frequency around the knee of the filter. Your original filter is around 'yellow'. You are moving towards brown, but not there yet.

Richard10 3rd September 2019 09:26 AM

Allen
Thanks for clarifying that for me. I will try a bit more capacitance.

AllenB 3rd September 2019 10:27 AM

You're welcome. By the way, it can sound wrong, dull or otherwise, but with a high pass added that sound no longer applies. With a correctly matching high pass it should sound right.

adzaj 12th September 2019 07:23 PM

Help with crossover, please...
 
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Couldn't find replacement drivers for Wharfedale E90's, because of a huge aluminium frame size of original 10 inch woofers. I made hole a bit bigger to accommodate 12 inch Dayton PA-310 woofers. Original woofers where 4 Ohm - Dayton's are 8 Ohms. They could be a bit louder to better balance with the rest. What would I have to change on the crossover to gain a few dB?
Thank you!
P.S.
I'm going to bypass LOW Selector, so Inductor L1 should be ignored since L1 and C1 will be bridged.

AllenB 13th September 2019 02:25 AM

I would turn the mid and treble level down. If this isn't enough I would put resistors across the mid and treble drivers. This would be a good idea anyway because R10 and R11 are already large. If you need more, increase those resistors in the switches.

Since the default is to have the woofer at max level I would tend to agree with you about L1 and C1, but they are interesting. They are intended to do some response shaping depending on your level choices but now the levels are being forced. They would cause some reduction in the woofer level with its middle point around 400Hz.

L7 is also only double L4, so its effect is worth considering. With a resistor in parallel this would give a shelving effect, a step with lows at one level and mids/highs at another, lower level with a slope in between. To some degree it would also be lowering the frequency of the filter that includes C6.

This is the thing when it comes to variable level controls. There are a couple of ways to do it. Either you can arrange components to isolate and preserve the driver response shapes, or whenever the controls are adjusted everything will be uniquely different.

With regards to the woofer, L5, C5 and R12 are reducing the level around 200Hz. It's hard to say whether this is to correct a driver issue, adjust for the baffle or something else. Could be worth temporarily shorting.

When it comes to the filter components L6, L3 and C2, for the 8 ohm woofer, double the inductors and halve the capacitors.

adzaj 13th September 2019 02:27 PM

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Thank you for quick reply!
It kinda hurts to kill overall sensitivity... I have these E90's stacked against Klipsch RF-7 and RF-7's are just a tiny bit louder. For now I'm using parametric equalizer in Yamaha RX-A3070 to correct the issue.
I'm gonna try shorting L5, C5 and R12, as you suggested and see what it does.
As for L6, L3 - L3 is already 10.0mH. 20mH is huge in size and also expensive... Is there any way that I could use the old one's and add to them? Parallel? Series?
The picture I attached illustrates what controls are supposed to do - you were right on the money!
Thanks again!

AllenB 14th September 2019 03:47 AM

Quote:

Originally Posted by adzaj (https://www.diyaudio.com/forums/multi-way/189847-introduction-designing-crossovers-measurement-post5913730.html#post5913730)
Is there any way that I could use the old one's and add to them? Parallel? Series?

I was thinking the same thing ;) Inductors in series will add, same for capacitors in parallel.

Richard10 22nd September 2019 05:16 PM

Increasing value of bass shunt capacitor
 
Allen B

A bit of feedback on my query in post 709.
Adding a bit of extra capacitance worked a treat. I only needed to replace that 2.2uf with a 3.3uf and minor tweaking of the tweeter resistor to effect a cure. Thanks for your encouragement.

AllenB 23rd September 2019 12:01 AM

You're welcome ;)


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