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Old 29th April 2018, 08:15 PM   #21
guidobullo is offline guidobullo  Italy
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Smile crossover

I made the crossover and its operation is excellent.
the analyzer tells me that the sine waves are as described by elektor, the sound reproduced with my system is qualitatively superior to commercial products that exceed 500 euros.
Comparative tests have shown its quality.
you know some scheme with superior reproduction quality, to indicate me to be able to realize it.
thank you.
guido bullo
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Old 29th April 2018, 08:23 PM   #22
guidobullo is offline guidobullo  Italy
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Default crossover

I insert the values I found on the web, and other files
Hello to all
Attached Images
File Type: jpg Elektor India 1987-10-36.jpg (296.1 KB, 192 views)
File Type: jpg Elektor India 1987-10-37.jpg (391.8 KB, 193 views)
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Old 30th April 2018, 07:49 AM   #23
jmbee is offline jmbee  France
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Quote:
Originally Posted by guidobullo View Post
I made the crossover and its operation is excellent.
the analyzer tells me that the sine waves are as described by elektor...
As you have it, you can easily test effective phase linearity with square waves.
Sum the outputs with a few resisitors an scope its wave form.
No longer square.
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Old 17th October 2018, 04:42 PM   #24
guidobullo is offline guidobullo  Italy
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Smile OP27/LME49710

Hi everyone
I have replaced in the OP27 AD buffer with a LME49710 and inexplicably there is an intense buzz on the woofer, I re-set OP27 and the buzz disappears.
To adapt the impedance of the Sony player I changed the value of the cermet bringing it to 100K, and the value of the capacitor to 1uf
With OP 27 and LME49720 everything works perfectly, while with 49710 no!
Can anyone tell me what the problem is and how to solve it?
If I had to replace the OP 27 with an AD817, can I get a better sound quality?
An OPA132P could be a better solution than the LME49710?
Thank you all
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Old 21st October 2018, 04:17 PM   #25
guidobullo is offline guidobullo  Italy
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Quote:
Originally Posted by Nelson Pass View Post
The key problem is that the standard sorts of filters are not tolerant of the
amplitude and phase errors of the loudspeaker drivers, and the summed results
for any driver whose bandwidth doesn't exceed the filter by a couple of octaves
are not usually good.

Siegfried Linkwitz dealt with it by equalizing and phase-shifting the driver as
part of getting a good response, although that is more complicated and tedious.

A simpler approach is to individually adjust the number and frequency of
the poles of the filter until you get a decent sum, something that you don't
find in fixed-formula filter sets. It still can be time consuming, but at least
it doesn't require additional circuitry.
grazie
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Old 21st October 2018, 04:48 PM   #26
Michael Bean is offline Michael Bean  United States
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Quote:
Originally Posted by guidobullo View Post
Hi everyone
I have replaced in the OP27 AD buffer with a LME49710 and inexplicably there is an intense buzz on the woofer, I re-set OP27 and the buzz disappears.
To adapt the impedance of the Sony player I changed the value of the cermet bringing it to 100K, and the value of the capacitor to 1uf
With OP 27 and LME49720 everything works perfectly, while with 49710 no!
Can anyone tell me what the problem is and how to solve it?
If I had to replace the OP 27 with an AD817, can I get a better sound quality?
An OPA132P could be a better solution than the LME49710?
Thank you all
The 49710 is a single opamp, the 49720 is a dual.

Mike
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Old 22nd October 2018, 10:03 AM   #27
guidobullo is offline guidobullo  Italy
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I do not understand the meaning of what you told me?
The filter works perfectly with OP27 AD, instead with LME49710 bought by Mouser you notice an obvious buzz, what I ask and to know the cause and a possible remedy, possibly
Hello
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Old 22nd October 2018, 10:07 AM   #28
guidobullo is offline guidobullo  Italy
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Logically, OP27 like LME49710 is used in the circuit as a buffer at the beginning of it.
So what you say does not make sense.
Hello
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Old 22nd October 2018, 12:44 PM   #29
Michael Bean is offline Michael Bean  United States
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Quote:
With OP 27 and LME49720 everything works perfectly
The OP27 and the LME49710 are single opamp chips, the LME49720 is a dual opamp chip which is a totally different pin-out, they are not directly interchangeable. The LME49710 also lacks the voltage offset trim function the OP27 has. These chips are not directly compatible, and unless the chip manufacturer specifically states compatibility, it's never safe to assume they are.

Mike
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Last edited by Michael Bean; 22nd October 2018 at 01:05 PM.
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Old 22nd October 2018, 12:57 PM   #30
guidobullo is offline guidobullo  Italy
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Quote:
Originally Posted by Michael Bean View Post
The OP27 and the LME49710 are single opamp chips, the LME49720 is a dual opamp chip which is a totally different pin-out, they are not directly interchangeable.

Mike
I am perfectly aware of the differences.
I do not care about LME49720 because it works perfectly in the filter.
What interests me to know is the reason for the buzz that voluntarily or involuntarily produces LME49710 to replace the OP27 in the circuit, I also want to clarify that the difference between the two chips and in favor of the 49710 that divinely sounds is significantly higher than the OP27. But it produces a buzz.
There is a zip file that you could open to understand the wiring diagram, located on page 1.
Hello
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