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Old 13th December 2004, 08:17 PM   #21
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Default Re: Re: Re: Chip amplifiers

Quote:
Originally posted by janneman



This is conflicting. A high cap supply will appear very close to a regulated supply. A low cap supply will heavily modulate output on peak signals, which both a high cap and a reg supply will do (much) less. Are you sure you haven't switched your statement around?

Jan Didden
Here is my understanding of more detail of the standard discussion:

The LMxxxx chips sound better in the mids and highs when they see lower capacitance (1500uF or so) rather than the 10,000uF or so in a standard power supply. As noted in the other posts this could be for inductance reasons etc.

The initial approach that started the DIY interest was the original Gaincard implementation that used smallish power supply capacitors. This was the original DIY approach that gained much DIY interest. Since the LMXXXX can handle a pretty noise PS, this works without significant hum etc.

The downside is that in demanding situations (difficult speakers, low end bass etc.) the reserve in the caps is to small (arguably) to effectively handle transients etc. So whether or not the classic gainclone 1,500uF approach sounds good has a dependency on the load you are driving.

The regulated approach has gotten a lot of interest recently because one can use large (2x4700uF) caps before the regulator, but small ones at the chip PS pins (33uF-100uF). The idea is that the chip sees low capacitance (or associated low inductance) but can get the current to handle transients and difficult loads.

So the move to try regulated has less to do with PS ripple and more to do with having a reservoir of power that appears to the chip as low (capacitance/inductance).
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Old 13th December 2004, 08:17 PM   #22
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Quote:
Originally posted by joensd
Well, the point I wanted to make is that you do generalize.
If you wanna make a statement youŽll have to explain.
Satisfied now?

Quote:
Originally posted by joensd
The whole amplifier topology is integrated.
There are so many ways of using a chip...
Including different topologies.
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Old 13th December 2004, 08:26 PM   #23
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Default Re: Re: Re: Re: Chip amplifiers

Quote:
Originally posted by demogorgon



Not with GC's. as everyone who have played with theese chips know, they sound like **** with high large reservoares of capacitance, or rather the inductans that the capacitans brings with it, to more or less extent.

I'm being rather bastant (as in dead certain that my knowledge is aqurate) here now, but this is regarded as a common fact concerning GC's is it not?

regards
marius
Common fact? How so? Might as well call it common delusion, no? I think you can find the same number of people that agree with you as those that don't. Carlos makes strong statements about this, and people start to believe it. But really it is nothing more than one persons personal opinion. I am not bashing Carlos, just pointing out how these mechanisms work.

However, the fact that low cap values do measureably and audibly modulate the output signal is 101 Electronics, not one man's opinion.

Now of course it is possible that you are right, but the probablility is slim in view of the conflict with repeatable and established demonstrations. What I most miss is the critical attitude of people scratching their head how such an apparent conflict could be possible. (Well, one exception. Dimitri DOES try to find an explanation).

Instead all follow unquestioningly the first statement. Even saying, yeah, but GC's are different. Hogwash! How would a GC which is a simple, outdated design amp of which there are 100's of similar types around, suddenly turn the laws of physics upside down just because they are called that way?

There are other threads on this forum where people make strong statements that an amp with a quasi-symmetrical output stage like so many GC's is horrible to listen to!


Jan Didden
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Old 13th December 2004, 08:32 PM   #24
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Carlosfm,

I think one notion is that it always comes across better when some one says:

"In my experience" or "In my extensive testing I have found"

rather than:

"I tested alot of configurations and therefore approach 'x' will never work because it did not work for me".

Not only is it better because people internalize your argument better, it is also more civil, leading to better dicussion.

Someone may hit on a great combination that is counter to your current implementations and priciples. You may think the chances are low but they are likely not 0%.
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Old 13th December 2004, 08:39 PM   #25
dimitri is offline dimitri  United States
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Default one person personal opinion

OK, TDA7294 power supply was optimized up to Shottky bridge, then CLC filter, 10000uF, 50mH, 10000uF.
But later, after 3xLM317/337 (in parallel) voltage stab addition all this iron can be thrown away, as now the filter has no influence, no more.
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Old 13th December 2004, 08:46 PM   #26
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Default As someone who has built more than his share of rotten sounding amps......

I can tell you that what you learn in Electronics 101 does not always apply to making an amp sound good. Especially wrt to cap values in the PSU.

Of course, there are plausible explanations for that.

Oh......wait...some of the hobbyists turned chip amp gurus will remind you that us engineers don't know how to "think outside of the box", and that only they can. Because their minds weren't corrupted by industry.

Yep...........being a chip amp guru.........priceless. (Real end of commercial.)

Jocko
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Old 13th December 2004, 08:59 PM   #27
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i would say with some black gates, caddocks 132 and some lt1083 regulated supply, they sound very good......within there power range.....biamped or triamped...better.
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Old 13th December 2004, 09:09 PM   #28
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Quote:
Originally posted by janneman
Carlos makes strong statements about this, and people start to believe it. But really it is nothing more than one persons personal opinion.
Oppinion?
Yes, why not?
Instead of throwing theories and ashes for the fire why don't you try it?
Believe who you want. I'm certain of what I say, you are not.
You guys seam to make amps "by the book", everything is so "datasheet"-like and so obvious, isn't it?
That is P-A's problem, he did a one-shot design, tried it, it works, let's sell.
No research, no refinement, just happy, just spot-on on first try!
Thats the Microsoft approach, one week after releasing people say it's no good.
While some of the best amps take months or even years of refinement and research to be made, this guy just throws a chip into a fancy green PCB and expects to make a revolution...

Jan, you should really listen to these chips with a high capacitance PSU.
You could do what you wanted, like I did, it would only sound good if you snubb it.
Otherwise, it's all generic theories.

Quote:
Originally posted by moving_electron
Carlosfm,
I think one notion is that it always comes across better when some one says:

"In my experience" or "In my extensive testing I have found"

rather than:

"I tested alot of configurations and therefore approach 'x' will never work because it did not work for me".

Not only is it better because people internalize your argument better, it is also more civil, leading to better dicussion.

Someone may hit on a great combination that is counter to your current implementations and priciples. You may think the chances are low but they are likely not 0%.
Great, be it as you want.
Let the others do the miracle, I don't believe in miracles.
Also, as you never tried what I am saying, you don't have any idea of who's right.
Do you?
So why discuss?

This thread was opened in MY NAME with words I never said, so the spanking has just begun.
Give me the opportunity to open a thread in P-A's name and I will do that.
Fair play?
Where?

roibm's thread was a review and a sharing of his experience with this amp.
I didn't know he was going to open a thread here, I was surprized.
He also opened that thread on the Gainclone forum to share his impressions on the sound of the amp.
He was banned from diyAudio.com!
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Old 13th December 2004, 09:18 PM   #29
ingrast is offline ingrast  Uruguay
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Quote:
Originally posted by carlosfm


....While some of the best amps take months or even years of refinement and research to be made...
Carlos:

I believe most well meaning people here are not satisfied by "how" your projects are better sounding.

I for myself should really appreciate at least an educated guess at "why".

Rodolfo
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Old 13th December 2004, 09:25 PM   #30
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This is what I've been up to lately.
It may be better than any LM chip, not sure yet, it's in-in, I'm testing.
It is a chip, one that demands a totally different approach and implementation.
It sounds fantastic.
What is it?
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