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Chip Amps Amplifiers based on integrated circuits

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Old 11th August 2013, 12:19 PM   #41
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Quote:
Originally Posted by iggy111 View Post
But why not build the FE like this, with optimizations, compensation and SMD parts, but keep the PSU (and even speaker protection) on separate boards?
It is obviously possible but, IMHO, it wouldn't be any better.

On the contrary the LM3886 PS of the FE makes use of not commonly used PCB techniques (in DIY audio pcbs) like striplines which are supposed to improve his performance.

I don't have the equipment to measure those differences but FE's subjective results seem to confirm my choice

Also, KSTR tested (measured) FE beta boards with good results regarding EMI performance of the PS and the board in geenral.
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Old 11th August 2013, 12:54 PM   #42
iggy111 is offline iggy111  Croatia
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Yes, I read a lot of comments about it's sound, so you did something right
And what are striplines?
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Old 11th August 2013, 07:14 PM   #43
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And what are striplines?
Sorry, wrong therm, the right one is Microstrip.

The advantage is that impedance is (almost) constant (so less reflections and distortion), radiates (and picks up) less, and inductance is reduced by 40%.
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Old 11th August 2013, 08:54 PM   #44
iggy111 is offline iggy111  Croatia
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Thanks for the explanation, I learned yet another thing.

I've just read a part of a long discussion on power supplies by some distinguished members of this forum, and the conclusion is that best power supplies are NOT built on separate boards, but comprise of putting the capacitors as close to the ICs or transistors as possible, calculating trace R and L, paralleling the right value caps etc...

A long read, but they actually quantified the reasons why their amps sound better, and some of which coincide with the FE version optimizations. I'll get back to reading now...
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Old 12th August 2013, 12:41 AM   #45
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Thanks for the explanation, I learned yet another thing.
You're welcome

Quote:
Originally Posted by iggy111 View Post
I've just read a part of a long discussion on power supplies by some distinguished members of this forum,
Can you post a link?
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Old 12th August 2013, 02:53 PM   #46
iggy111 is offline iggy111  Croatia
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Two topics actually, this is the first:
Bob Cordell Interview: Power Supplies

And this one (maybe even better):
Power Supply Resevoir Size

In this particular post from the second topic you have a few more links:
Power Supply Resevoir Size

Hundreds of pages, enjoy
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Old 12th August 2013, 06:15 PM   #47
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thanks
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Old 16th December 2013, 12:00 AM   #48
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Was able to test the amp today, I got 45Watts into 4 ohms resistive dummy load using 8Amps 24-0-24VAC transformer. (Single channel driven)

As for the sound, It has a wide soundstage and superb detail, the instruments sounded lively.
I compared it to my LM3875, this one has more detail and the bass has more punch. The LM3875 is much softer/smoother though.

For me the sound character is much like BAKSA 50 but with more refinement, more details and more accurate bass.
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Old 16th December 2013, 02:57 AM   #49
Bigun is offline Bigun  Canada
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Hi,

That's a very nice build by the way.

I'm new to Chip amps. I'm going to build a simple version first to see how it goes. But it's interesting to read about other designs. This design appears to use the LM3886 as a current driver and another opamp for the voltage gain.

So when listening to this amplifier I assume that it is the LM318 that 'sets the tone' for the sound and not the LM3886 ?
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Old 17th December 2013, 12:54 AM   #50
macky is offline macky  Philippines
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Quote:
Originally Posted by jlester87 View Post
Was able to test the amp today, I got 45Watts into 4 ohms resistive dummy load using 8Amps 24-0-24VAC transformer. (Single channel driven)

As for the sound, It has a wide soundstage and superb detail, the instruments sounded lively.
I compared it to my LM3875, this one has more detail and the bass has more punch. The LM3875 is much softer/smoother though.

For me the sound character is much like BAKSA 50 but with more refinement, more details and more accurate bass.
so which layout did you use? is it on the post #31?

Last edited by macky; 17th December 2013 at 12:58 AM.
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