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Active crossover design advice.

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Imagewerx

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Hi Guys.I'm looking at building the crossover as shown below......

https://www.te1.com.br/2012/08/high-pass-crossover-ativo-2khz-4a-ordem-butterworth-automotivo/

I'll be making it as a stereo high and low pass,obviously swapping the resistors and caps over to make a low pass section.What I need to know about this design is....

1.The L7660 voltage convertor,is it manly enough to supply the whole four way circuit by itself,or do I need one per op amp?

2.They specify an LM833 op amp,is this an ok kinda device or could I do better for not a massive amount of money? It'll be used in a reasonably high end install with Phoenix Gold midbass and Image Dynamics horns but not for competition use,so absolute perfect quality isn't that important.

3.Is this actually a Butterworth design? My very basic understanding of such circuits suggests to me that it's actually a Linkwitz-Riley,and although all the designs seem to suggest L-R is preferred for such things,is this actually a good enough design for an in-car 24db/octave crossover?

I have actually e-mailed the designer of the circuit to answer these questions,but as he hasn't got back to me hopefully I can find the answer here.

Chris,
 
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I don't understand the language of your referenced link. Is there an English version?
 
Sorry I just used the translator in Google Chrome,here's how it goes.......

Hello
This post is related to a high pass crossover, active 4th order, 24dB/octave with cutting frequency 2KHz. Creating encouraged by the lack of equipment of the type available in the market, the circuit is very simple, small and easy it takes very little to make it.
The tests were done with a Driver TI Automotive, which needs this type of cut, showing a great performance, but the car had a noise connected (as machine dentist) but I believe the uo of some capacitors and / or in a box aluminum this noise ja slow down a bit. This noise also varies with the car and the cable that is being used.
In my case I used an RCA player (radio) to the outlet of the crossover and bound crossover RCA input on the amplifier module (power).
The IC 7808 is a reguldor voltage because the 7660 only operates up to 10V. 7660 is a DC-DC onversor to generate a source / negative voltage and LM833 is an amplifier dual operational happens where the high pass cut itself.
 
Afraid the translation is only slightly more understandable then the original language. :rolleyes:
 
Hopefully it gets the general message across though.As electronics is supposed to be a kinda universal language,at least my questions should make sense?
 
Ok,think I've figured how to make it a Linkwitz-Riley alignment by altering the relationship between the components in the R/C network.

Now all I need to know is the bit about the voltage convertor and what sort of audio quality I can expect from an LM833 and could I do better?
 
My problem is I see no schematic on that website.
 
Neither do I,but it works with the accepted layout for a 4th order high pass crossover. The reason I'm interested in this one is that I can get my head around the crossover bit easily enough,but as I've never used op amps before,the split power supply thing is like voodoo to me and I couldn't work out a definitive answer by myself of how to do it with a single 12 volt supply.This one seems to show exactly what I need in a way I can understand it.
 
If you don't have a schematic, how do you know you need a split supply? :confused:
 
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You found a foreign very old design (the LM833 was a preamp for a vinyl records pickup, remember them? But the LM833 is fine in this project, also you could use a TL072) and the old ICL7660's output voltage changes as the current from the opamps changes with the signals. You might be able to hear its 10kHz operating frequency.

Here is an Australian Linkwitz-Riley 24db/octave crossover project. They speeky zee English there.
**broken link removed**
Maxim has a more powerful positive to negative charge-pump IC that has a regulated output and it operates at a very high frequency that you cannot hear.
 
If you don't have a schematic, how do you know you need a split supply? :confused:
Because as I said above I've never used op amps before and as I understand them now,they all need a split supply?

You found a foreign very old design (the LM833 was a preamp for a vinyl records pickup, remember them? But the LM833 is fine in this project, also you could use a TL072) and the old ICL7660's output voltage changes as the current from the opamps changes with the signals. You might be able to hear its 10kHz operating frequency.

Here is an Australian Linkwitz-Riley 24db/octave crossover project. They speeky zee English there.
**broken link removed**
Maxim has a more powerful positive to negative charge-pump IC that has a regulated output and it operates at a very high frequency that you cannot hear.
Yes I remember vinyl like it was only yesterday. I have seen the Elliot Sound Products design and was thinking it'd be easier just to go with that sort of design.But, I'm on a VERY tight budget and couldn't afford to get a couple of his PCBs shipped across from Australia to England,so need to be able to make it all myself.His schematic doesn't show the power supply,which is the bit I'm struggling with at the moment.
What is a "Maxim",and have you got any part or model numbers please?

Chris.
 
His schematic doesn't show the power supply,which is the bit I'm struggling with at the moment.
Its on the board layout, An ICL7660 or LMC7660 voltage converter chip is used to make the negitve supply.
What is a "Maxim",and have you got any part or model numbers please?
Maxim is a chip maker.
Look up maxim negative voltage converter.
 
ANY opamp can use a single-polarity supply if its input is biased at about half the supply voltage, it has a DC voltage gain of 1 and it uses coupling capacitors. Then it makes a nice POP when powered up or when turned off as the capacitors charge or discharge.

The pcb from Brazil will probably work with Linkwitz-Riley parts except its HUGE antique film capacitors are much smaller today.
 
Its on the board layout, An ICL7660 or LMC7660 voltage converter chip is used to make the negitve supply.

Maxim is a chip maker.
Look up maxim negative voltage converter.
Thanks,but I know where the power supply is on the board I linked to,I meant it's not shown for the Elliott Sound Products design.Never heard of Maxim as a chip manufacturer,looked 'em up and now I have:D.
ANY opamp can use a single-polarity supply if its input is biased at about half the supply voltage, it has a DC voltage gain of 1 and it uses coupling capacitors. Then it makes a nice POP when powered up or when turned off as the capacitors charge or discharge.

The pcb from Brazil will probably work with Linkwitz-Riley parts except its HUGE antique film capacitors are much smaller today.
Ok,so no single power supply for me then.Can I substitute the old fashioned one in the Brazilian design for one of these modern Maxim devices with the same pinouts,but no problem if I have to redesign my PCB?
I would be substituting them for more modern caps anyway,can I use 1% SMDs,or are they not suitable for audio circuits?
 
Find the Maxim charge-pump regulated voltage converter on Maxim's www.maxim-ic.com website, see if you can buy it in England then look at its pinout compared to the old ICL7660 IC.
 
No, that is just another copy of an old ICL7662 but with a higher supply voltage spec. Its output voltage wanders when the load current changes. The Maxim one has more output current and has voltage regulation.

Sorry I can't find the Maxim one, they have many charge-pump voltage converter ICs. An LT1054 and ADP3604 might be the same.

Also,what about the SMD caps in audio circuits?
Ceramic coupling capacitors cause distortion. Use film caps. Are there any film SMT caps available?
 
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