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Discrete vs opamps... - Page 5

post #61 of 176
1/26/06 at 1:45pm
Quote:
Originally Posted by wakked1
Just a note regarding temperatures... amp like engines should be built to operate optimally at their fully warmed up & loaded state. I thought it was just my imagination but even the GL sounds significantly better after at least a few hours of warmup.

They are and thus I never turn mine power amp off. Keep in mind that temperatures can change dramatically when the amp is playing music.
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post #62 of 176
1/26/06 at 2:01pm
Well, I confirmed my answer:

"the dissipation is maximum at idle in a class A amplifier, and does not increase with applied signal, as it does in a class AB or class B amplifier (it actually decreases to a minimum at full power)."

From this site:

http://www.aikenamps.com/ClassA.htm
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post #63 of 176
1/26/06 at 2:08pm
Quote:
Well, I confirmed my answer:
where does that differ in any way with my responses ?

am i missing something
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post #64 of 176
1/26/06 at 2:33pm
Are we talking about amps for speakers of headphones?
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post #65 of 176
1/26/06 at 2:44pm
Quote:
Are we talking about amps for speakers of headphones?
Does not matter.Class of operation holds to the same laws no matter what it drives and pure Class-A is FULL THROTTLE from the time you hit the "on" switch until you turn it off no matter what it drives and why no I.C. opamp can be pure class-A and why (back to original question) discrete opamps are better than chip opamps in all cases all the time if sound quality is the guage
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post #66 of 176
1/26/06 at 3:49pm
well, in discrete design, transistors have to be matched by hand. In an chip opamp you can be sure not only they are matched, but they are laser trimmed to very high precision. And I am pretty sure a chip opamp has lower parasitics than discrete.

The reason I mentioned about amp for headphones and speakers is that I saw some people were worrying about heat as a factor, I just want to say that for headphone amps the output power is very low. (most headphones have sensitivity of 80-95dB/mW)
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post #67 of 176
1/26/06 at 3:54pm
Quote:
well, in discrete design, transistors have to be matched by hand. In an chip opamp you can be sure not only they are matched, but they are laser trimmed to very high precision. And I am pretty sure a chip opamp has lower parasitics than discrete.
So ? Explain to me how that translates into either good sound or bad sound and why that spec is so important to you over mode of operation.

Quote:
The reason I mentioned about amp for headphones and speakers is that I saw some people were worrying about heat as a factor, I just want to say that for headphone amps the output power is very low. (most headphones have sensitivity of 80-95dB/mW)
one more time....

class-A sounds better than A/B everything else being equal and NO I.C. Op-Amp can be made to operate in pure class-a or it WILL burn up.This has zero to do with power levels and what headphone is used but everything to do with class of operation,what sounds better and why discrete is better than monolithic
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post #68 of 176
1/26/06 at 4:54pm
I get a sort of perverse pleasure from running my E4's from a class A mosfet
follower, the thing just sits there merrily dissipating heat using way more
power than the little E4's could ever use on their own.
Of course there are those who would frown on such a seemingly wasteful use
of the worlds resources...


.
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post #69 of 176
1/26/06 at 4:59pm
Quote:
Of course there are those who would frown on such a seemingly wasteful use
of the worlds resources
well that does not include me man !

Pure class-a means great and consistant sonics across the board no matter what the output level right up to clipping so what is wasteful about that ?

Just don't sit too close with a lot of clothing on or "dance naked" will take on a whole new meaning...........................
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post #70 of 176
1/26/06 at 5:07pm
Quote:
Originally Posted by rickcr42
class-A sounds better than A/B everything else being equal and NO I.C. Op-Amp can be made to operate in pure class-a or it WILL burn up.This has zero to do with power levels and what headphone is used but everything to do with class of operation,what sounds better and why discrete is better than monolithic
Agreed discrete class A is the way to go whenever possible. Class A has always sounded better to me and is one reason why I own my current amp.
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post #71 of 176
1/26/06 at 5:15pm
With nearly every headphone I have heard, particulary ones I live with, there is so little difference between nearly all single ended headphone amps. Even comparing (properly designed and made) tube amps.

If two amps sound significantly different, it is for three reasons.

1. Enough time has passed between the listening of both amps, placebo effect is a factor.

2. Listening was done in a different and louder setting (like a Meet), and listening was done at a higher volume than what is normally listened to. Higher volume = greater perceived dynamics and excitement.

3. There is something wrong with the design or build of one of the amps.

I perfer to live with components in a quiet setting like at home to truly compare amps. And at noisy meets, a well made switch box is my preferred method of comparison.

-Ed
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post #72 of 176
1/26/06 at 5:21pm
I have been quite intrigued by Nelson Pass's current source amps. [1st watt]
That sort of design could rather good for driving ribbon phones....
Nelson's site[s] are are wealth of information for those who enjoy the class A minimalist appraoch.

http://www.passlabs.com/




.
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post #73 of 176
1/26/06 at 5:23pm
Quote:
With nearly every headphone I have heard, particulary ones I live with, there is so little difference between nearly all single ended headphone amps. Even comparing (properly designed and made) tube amps.
This is not about single ended or tubes vs solid state but which is better :

A discrete opamp or a monolithic opamp and since Class-a is clearly audibly surperior in every listening test I have ever done and no chip opamp can be made to operate in class A my conclusion,and one that most who have compared the two agree with,is a discrete class-A op-amp not only wins but by a wide margin over any monolithic chip Op-Amp
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post #74 of 176
1/26/06 at 6:44pm
Just a quick technical question: Is there a difference between 'discrete opamp' designs and what's normally discussed as discrete designs such as the Gilmore amps or the Headcode?

And one thing I wonder is that if normal opamp-based amps are supposed to be inferior, then why are there so many accolades on the Headroom Blockhead / new balanced Max? I never heard these things myself but the comparisons are always very favourable. My initial gut feeling before reading through the thread was that "discrete > opamp" is more like a sweeping statement because I've heard really nice opamp-based amps like the Prehead but was a little bit let down by discrete amps such as the Dynamight; a very good amp mind you but with a few drawbacks I couldn't live with.

In any event, this is another one of those educational threads. I would only love to hear the opamp side's take on this by somebody equally knowledgable as Rick for instance. Too bad that amp manufacturers probably can't take part in discussions like these. Otherwise I would be very interested why manufacturers like Headroom and Meier-Audio stick with opamps even in their high end amps.


To draw out a small conclusion for less technically-versed readers like myself: Is simply not worth bothering with opamp-based amps costing more than, let's say, $800-1000? Or would that be a sweeping statement?
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post #75 of 176
1/26/06 at 6:54pm
Quote:
Originally Posted by rickcr42
So ? Explain to me how that translates into either good sound or bad sound and why that spec is so important to you over mode of operation.
In the realm of electronics themselves (not talking about audio here), chip opamps have much ower offset voltage and biase current (these are the two main DC imperfections of real opamps compare to an ideal opamp) due to the transistors are laser trimmed.

Forget about the other comment, you misunderstood my intention of the post but it is not important anymore, I did not explain my intention clearly in the first place, it's my fault.
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