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Multi-Way Conventional loudspeakers with crossovers

Introduction to designing crossovers without measurement
Introduction to designing crossovers without measurement
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Old 18th May 2019, 01:06 AM   #691
brooks is offline brooks  United States
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Btw - I do have the specs and freq graphs for all Philips drivers. I have found some great old docs on these, and also found a gem of a online book by M.D. Hull of Philips ‘Building Hi-Fi Speaker Systems’, from 1980, which includes specs on my drivers, acoustic theory, loudspeaker design, and example systems.

In doing some tests, I’ve found that one mid (Mid#2) is damaged, as its output is about nul and distorted. So I am replacing them with the same type as the Mid #1 (AD5060) which I feel better not having two different mids to worry about with different responses. I’ll remove the bandstop add a simple bandpass and should have a much better speaker. Thanks again.
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Old 21st May 2019, 06:01 PM   #692
Tournesol is online now Tournesol  Belgium
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Quote:
Originally Posted by AllenB View Post
We'll need to use one resistor and one capacitor (per woofer).
I have not read the entire thread, and, may-be some one has even said this, but this is far to be optimal.
To linearise a speaker, you need to compensate both its inductance, by a RC network in parallel, and its peak of impedance at its resonance frequency, by a RLC network, in parallel too.
See:
La correction d impédance RC série
La correction d impédance RLC série
La correction d'impédance RC et RLC série

As the good speakers manufacturers usually provide the impedance curve of their speakers, no need to any measurement on your side.
After the correction done, you will have a flat impedance curve, usually at the DC resistance of the coil (6 Ohms for a 8 ohms speaker, 3 for a 4 Ohms). And you can easily calculate your filter on the theoretical values, it will work as expected.
Just my two cents..
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Last edited by Tournesol; 21st May 2019 at 06:03 PM.
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Old 22nd May 2019, 02:09 AM   #693
AllenB is offline AllenB  Australia
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This is a good tool. I have used this technique of RLC compensation on a woofer's impedance when I introduce a finite source impedance. For example a crossover or an amp. It can help to get the wanted result.

I considered this when starting this thread. My thoughts were that typical woofer resonance is around or below 100Hz. Typical crossovers of this kind, are around or above 1kHz. This is an order of magnitude difference. In other words, this is far enough apart in frequency that the interaction can be considered insignificant for most purposes.

I also find RLC compensation is something that can be applied to a tweeter at its resonance.
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Old 23rd May 2019, 01:38 PM   #694
Tournesol is online now Tournesol  Belgium
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Quote:
Originally Posted by AllenB View Post
This is a good tool. I have used this technique of RLC compensation on a woofer's impedance when I introduce a finite source impedance. For example a crossover or an amp. It can help to get the wanted result.

I considered this when starting this thread. My thoughts were that typical woofer resonance is around or below 100Hz. Typical crossovers of this kind, are around or above 1kHz. This is an order of magnitude difference. In other words, this is far enough apart in frequency that the interaction can be considered insignificant for most purposes.

I also find RLC compensation is something that can be applied to a tweeter at its resonance.
This practice (RLC for all speakers) has 4 major benefits.
1- It helps to have theoretically calculated passive filters to work as expected, not having to tune them on the bench with a mic.
2- It helps the speakers , as they have now a flat impedance curve, to keep their response curve unchanged, whatever the serial impedances of the cables and passive filters.
3- It helps to improve the damping of the speakers: you can easily hear the difference (power amps off), by hitting the membrane of the boomer with your finger.
4- It helps the amplifier(s), especially their power supplies, to get more coherency all over their frequency range, having no more to deal with a schizophrenic Voltage:current behavior. May-be too, we will enjoy a benefit on the micro dynamic looking at the levels in their feedback paths to compensate the difference between voltages/currents VS frequencies.

About the "insignificant", OMHO, the best speaker assembly is the one with the less ways as possible, to reduce the acoustic problems of crossovers (phase turns etc.).
So, in my case a two ways (with horn), the crossover frequency is not so far from the resonance frequency of my horn driver, and close too to the first break of the membrane of the boomer. I can hear the difference, despite my filters are 48dB/oct, comparing with/without RLC comp. on each of the two speakers.
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Last edited by Tournesol; 23rd May 2019 at 01:43 PM.
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Old 23rd May 2019, 02:46 PM   #695
picowallspeaker is offline picowallspeaker  Italy
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A boomer!
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Old 23rd May 2019, 03:22 PM   #696
AllenB is offline AllenB  Australia
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I agree that the impedance of a compression driver, and a horn with a cutoff frequency, can be a significant problem. Also these often have to be cut close to their limits to suit other needs.

I have some concerns with other points you have made, but at this level I have no problem with them.
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Old 24th June 2019, 05:10 PM   #697
Breadfan is offline Breadfan  United States
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Thank you Allen B. I have studied your thread and made sure I understood everything before I took the plunge into XO's. I love it. I have been very successful on my first attempt to make really good sound. I am still tweaking my design but I have found that is the best part. I tweak something and then listen, maybe minute, maybe hours before I think it may need more tweaking. I really feel like I have accomplished a lot! Such a great thread!!!
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Old 25th June 2019, 02:11 AM   #698
cgunawan23 is offline cgunawan23
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Hello Allen B, it has been 8 years since you published this tutorial, thank you and thank you, I wish I have a better words to express my appreciation.
XO design has been a show stopper for a newbie DIY like me to embark to the next journey, and you have removed this barrier.
Great job and you shall be proud with your work.

Chandra.
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Old 7th July 2019, 08:08 PM   #699
tubemax is offline tubemax  Netherlands
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Hello Everybody,

I used this tutorial to finish my small speaker project, many, many thanks to the original author for simple and understandable language in explaining problem during designing passive crossover!

I did use on occasion Boxsim program from Visaton website, it was a nice software tool to play around with changing parameters to death but I felt you are never sure how is going to turn out on the end.
To help myself and shorten the developing time I decided to make kind of universal crossover and play with parameters live while listening.
Inside of blue box was hidden 12db or 18 db adjustable high-pass crossover for tweeter with attenuator, polarity switch and choice of 3 different coils… each capacitor bank could go from 0,5uF up to 22uF… in short I could emulate in real-time and listen to the effect.
I have to say it was revelation as you could accurately fine-tune without guess work, but I did not measure final result. This will have to wait until I buy proper microphone.

Mini speakers that I worked this time were 2-way closed box design inspired by BBC Research done in the 70’s designing small monitor speakers for broadcast. I did not copy any of drawings from LS3/5a, just followed designed guidelines and choose myself off the shelf drivers I could afford.
Mini monitors are based on Visaton W130S woofer and Dayton Audio RST28A tweeter as the best candidates without breaking the bank.

I finally came to conclusion that 12db crossover sounded best all-round but 18db was a tad more compressed in comparison. Point here is that you would not have idea how what sound unless is accessible on flick off a switch.

Still, the work done on software program was crucial in finding sweet spot to start with, especially low-pass part of crossover, so once I settled on low-pass, I further spent time with variable high-pass to great delight as you could hear every adjustment and spend some quality time in fine tuning and experimenting.
I could post drawing of crossover if there is interest, for time being just a couple of photos of the speaker and adjustable high-pass crossover.
Attached Images
File Type: jpg Mini 1.jpg (980.0 KB, 107 views)
File Type: jpg Mini 2.jpg (1.04 MB, 107 views)
File Type: jpg Front & back panels.jpg (878.4 KB, 102 views)
File Type: jpg Final crossover.jpg (1,008.5 KB, 112 views)
File Type: jpg Variable 12db:18db crossover copy.jpg (549.8 KB, 110 views)
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Old 7th July 2019, 10:26 PM   #700
Spinifex is offline Spinifex  Australia
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I love those photos of the 'working crossover.' I mean, I REALLY like it. Could you post some more please for us 'mere mortals' to have a closer look at.
EDIT: And... "YES PLEASE" to the drawings of the cross over. This is my dream come true.
https://www.diyaudio.com/forums/atta...sover-copy-jpg https://www.diyaudio.com/forums/atta...-crossover-jpg

Last edited by Spinifex; 7th July 2019 at 10:28 PM.
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