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Chip Amps Amplifiers based on integrated circuits

Are Discretes Better Than Chip Amps?
Are Discretes Better Than Chip Amps?
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Old 19th July 2003, 12:32 AM   #41
millwood is offline millwood  United States
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Default Re: Re: Re: Re: Re: Re: summarizing...

Quote:
Originally posted by Kuei Yang Wang
I prefer to get the basics right, before I start fishing at the edge.... BWTFDIK.

Sayonara

I respectibly disagree. As you long as you pay >$1K for your cap and $2K for your resistors, your amp will sound fabulous, regardless of its topology, or build quality.



Oh, don't forget about damping,
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Old 19th July 2003, 12:35 AM   #42
ThorstenL is offline ThorstenL  Germany
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Konnichiwa,

Quote:
Originally posted by nobody special

2- Lowest measured distortion- This school of thought uses all the tricks- current sources, mirrors, active loads, etc. If another stage will lower the distortion, go for it! Feedback in whatever amount gets the job done is acceptable.
Actually, much what you mention helps INHERENT LINEARITY, meaning it stops or reduces alterations to the wholey, holey and only signal. It does so, if well applied without resort to either local or global positive or negative feedback.

Quote:
Originally posted by nobody special

Op amps fall into this category, no matter how much (or little) wire you use to hook them up.
Note anything with a positive and negative input plus an applied feedback loop is a "Op-Amp", even the single FET in the PassZen or a single triode with Anode to grid loop feedback.

Quote:
Originally posted by nobody special

I fall into the first category,
You mean the category which uses "bad" op-amps with feedback?

I belong to the zeroeth category which regards feedback as a tool to get certain results, which like any tool needs application with care. Feedback is no pankea to solve all problems and in my own system at home I prefer to do without.

From MC Pickup to Speaker Output I have 4 active devices, no feedback, not even "local" feedback, all supplies are unregulated. Of course, most of the time I add a digital equaliser via it's analogue inputs into the mix, which has at least 100's of active stages (real or virtual), loads of Op-Amp's, negative feedback etc.

But of course, I did not design the EQ (I did modify though) I just find it works.

Quote:
Originally posted by nobody special

1. I believe that greater amounts (but not ridiculous amounts,
of course) of low order distortion is preferable to smaller
amounts of higher order distortion.
Of course. That is 1950's stuff, read Shorter, Olson and Crowhurst from those days when the JAES was not "just toing the party line". There are plenty more publicatiosn. Including some which suggest higher degrees of "ear congruent" distortion can enhance audibility by a process best translated as "residiium hearing"

Quote:
Originally posted by nobody special

2. I believe that feedback, which is a subtractive process, tends to subtract more than just distortion when overused.
Actually, feedback is NOT a subtractive process. It is ALLWAYS additive.

Secondly, feedback does "subtract" distortion, it redistributes it into different domains (PIM/TIM) and spectrae, hencemy insistence on INHERENT linearity. If nothing goes wrong to start with there is no fallout from fixing it.

Of course, on the additive nature of feedback, the sign of some of the added components may be negative, but the feedback node is ALLWAYS and INHERENTLY additive.

So, at best feedback only adds the signals with signs and magnitudes.

In reality it adds many others... Simply killing the common mode element in this additive process (using inverting mode) helps tremendously, interestingly BOTH objectively and subjectively.

Quote:
Originally posted by nobody special

With these "I believes" it sounds a little like religion, and that might not be far from the truth.
Actually, it sounds like a completely irrational religion AND it is very far from the truth. At least from where I stand.

Quote:
Originally posted by nobody special

Anyway, if I were to build a "type 2" amp, I would probably not bother using discretes, because it is pointless.
Agreed. Valves sound much better and in the dark they glow much longer....

Quote:
Originally posted by nobody special

So, my vote is- discretes are better for minimalist techniques,
Assuming your devices are "good enough", which sadly excludes solid state almost wholesale, Admiral Nelsons protestations ("It's only a fleshwound") nothwithstanding.

Solid state requires the added complexity that makes chips near mandatory to actually work well enough for music. Oh, it requires almost allways some for of (looped) feedback too.

Sayoanra
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Old 19th July 2003, 08:54 AM   #43
jan.didden is offline jan.didden  Europe
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Default Re: Re: Re: Re: Re: Re: Re: summarizing...

Quote:
Originally posted by millwood



I respectibly disagree. As you long as you pay >$1K for your cap and $2K for your resistors, your amp will sound fabulous, regardless of its topology, or build quality.



Oh, don't forget about damping,
I respectfully declare this total and utterly nonsense. First comes the topology, the type of components (FET? BP? Tubes?) the the detailed diagram, then the implementation. And then IF you get all this optimised, you can indulge in 100$ resistors, and convince yourself it really makes a difference. But make a non-optimal choice in one of the basics, and no amount of money thrown at it makes a difference (except on the price).

Jan Didden

(Yes I know you were only joking, but a lot of people here may actually BELIEVE you, for pete's sake)
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Old 21st July 2003, 08:35 AM   #44
carlosfm is offline carlosfm  Portugal
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Default Re: Re: Re: Re: Re: summarizing...

Quote:
Originally posted by millwood

Well, with a few tweaks, y ou can get excellent sound out of that amp, including that woeful NAD. start with gold-plated resistors, plentium coated caps, tungsgen reinforced heatsinks, 14K white gold jacks, and silver-plated cover, you don't have to worry about those sucky transistors anymore.

BTW, don't forget about using aluminum oxide insulation pads.



As they say in banking, there is no bad amp, just with the right resistors,
Well, just for reference, my Nad is a Monitor Series Receiver 7000.
My money couldn't buy better about 12 years ago.
It's extensively tweaked.
Hey millwood, even with all those things you wouldn't go far if you didn't replace those nasty JRC op-amps on the preamp.
My Nad has OPA2132.
And it plays very well indeed, but still not enough current/PSU (?) to drive my Epos 11 speakers properly.
But let's say this amp, as it is now, is good hi-fi.
My GC is high-end.
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Old 4th August 2003, 09:15 PM   #45
MarcelvdG is offline MarcelvdG  Netherlands
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One disadvantage of chip amplifiers I haven't seen mentioned explicitly yet:

I don't know for sure if this applies to the National Semiconductors chips (I would be surprised if it didn't, though), but with some expensive exceptions, most bipolar IC processes have only very bad lateral PNP's with a very low current handling available. This is in fact why quasi-complementary output stages are so popular in monolithically integrated amplifiers. Making a fully complementary output stage with lateral PNP's would be difficult to do and would require an enormous chip area.
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Old 4th August 2003, 11:45 PM   #46
ThorstenL is offline ThorstenL  Germany
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Konnichiwa,

Quote:
Originally posted by MarcelvdG
One disadvantage of chip amplifiers I haven't seen mentioned explicitly yet:

I don't know for sure if this applies to the National Semiconductors chips (I would be surprised if it didn't, though), but with some expensive exceptions, most bipolar IC processes have only very bad lateral PNP's with a very low current handling available. This is in fact why quasi-complementary output stages are so popular in monolithically integrated amplifiers. Making a fully complementary output stage with lateral PNP's would be difficult to do and would require an enormous chip area.
Actually, not only IC's have usually "bad" PNP Transistors. In virtually ANY "complementary pair" the NPN (or N-Channel) transistor has a higher Beta, better Beta linearity and a higher Ft.

That's solid state for you. There where good reasons why the old masters never made a "P-Channel" Tube....

Sayonara
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Old 4th August 2003, 11:48 PM   #47
fdegrove is offline fdegrove  Europe
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Hi,

Quote:
There where good reasons why the old masters never made a "P-Channel" Tube....
LOL...

Man oh man...

Good one Thorsten,
__________________
Frank
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Old 5th August 2003, 12:36 AM   #48
Steve Eddy is offline Steve Eddy  United States
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Quote:
Originally posted by Kuei Yang Wang
Actually, not only IC's have usually "bad" PNP Transistors. In virtually ANY "complementary pair" the NPN (or N-Channel) transistor has a higher Beta, better Beta linearity and a higher Ft.
Aye, but then that could be seen as beneficial as it would produce an asymmetry between the pairs increasing second/even order distortion giving it a somewhat more "single-ended" characteristic.

se
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Old 5th August 2003, 12:43 AM   #49
ThorstenL is offline ThorstenL  Germany
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Konnichwa Eddy San,

Quote:
Originally posted by Steve Eddy


Aye, but then that could be seen as beneficial as it would produce an asymmetry between the pairs increasing second/even order distortion giving it a somewhat more "single-ended" characteristic.

se
Sure.

So, you are saying that all the people who listen to fully complementary Solid State Amp's REALLY only like to listen to distortion? Works for me, Let's run with it....

Sayonara
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Old 5th August 2003, 03:05 AM   #50
Steve Eddy is offline Steve Eddy  United States
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Quote:
Originally posted by Kuei Yang Wang
So, you are saying that all the people who listen to fully complementary Solid State Amp's REALLY only like to listen to distortion? Works for me, Let's run with it....
No, what I said was:

Aye, but then that could be seen as beneficial as it would produce an asymmetry between the pairs increasing second/even order distortion giving it a somewhat more "single-ended" characteristic.

se
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