Whats wrong with large filter caps for Gainclone?

[Pedja]

Originally posted by Mesh
The problem I have with that is that the data sheets are aimed at low end applications - not esoteric HIFI.

Hi Mesh,

Datasheets and application hints you find in them are basically not aimed neither for low- nor for high-end applications, but only for applications. Of course, you can think the ways to improve the manufacturer’s suggestions, but before you do that, it is not bad to realize what the manufacturer did want to say with them. But anyway, it is wrong to think about the application hints as they are written exclusively with the intention to lower the building costs. Just check the datasheets more carefully, you might be surprised what you can find in them. A lot of very competent and useful suggestions usually completely overlooked and ignored. You might find a lot of useful info that is actually enough for making of the very high end equipment.

(Yes, I do know that the National says that the LM3875 doesn’t require a regulated supply and I am using it.)

Pedja

[millwood]

Originally posted by Pedja

Did you miss something here?

Pedja

I have yet to say an application that specifically says a chip/transistor/device is designed for low-performance applications.

Does anyone know what the original ua741 datasheet say about it as to if it is a high performance chip?

[janneman]

Originally posted by Mesh


The problem I have with that is that the data sheets are aimed at low end applications - not esoteric HIFI. I dont think National would ever recommend 30000 uF for a chip amp. I also dont think they would be suggesting 300 VA or 400VA per channel! for a 30 watt amp running class AB.

Well, since National is in the business to make money from sales of these chips, I would think that they publish app notes that produce sales - i.e. best quality for the cost. Since competition between chip makers is cutthroat, you can bet your sweet afterpart that they take this VERY serious.

Now in esoteric hifi one may want to chose say, a 300-400VA xformer. Since I happen to know that the xformer is disconnected from the amp for about 85-90% of the time, I find it difficult to believe this would make for a huge improvement.

30.000uF is another story. It is entirely possible for the sound quality to deteriorate with increasing capacitance, if you look at the spectrum of the charge pulses in relation to the amp PSRR. Agreed, the GC chips seem to be good here.
I use the rule of thumb: 1000uF per amp of max load current. For a gainclone that would IIRC be about 8,000 uF.

YMMV

Jan Didden

[janneman]

Originally posted by Nuuk
Here we go again! Another drawn out debate over something that is surely subjective.

It is so easy (and reasonably cheap to build one of these Gainclones that it could be done in less time than it takes to read threads like this.

So the answer is build one - with a standard supply, a regulated supply, with two or even four transformers, one, two or four bridges, with small caps, huge caps or with batteries.

When somebody has built the lot, they can post on a thread like this with some authority. Otherwise we are just going over the same ground yet again; and I'm trying to avoid ruts!

Authority for what exactly?

Jan Didden

[Pedja]

Originally posted by millwood



I have yet to say an application that specifically says a chip/transistor/device is designed for low-performance applications.

Does anyone know what the original ua741 datasheet say about it as to if it is a high performance chip?

No, I do not know what was claimed in the 741’s original datasheet but if it was the best chip for its own time, what is strange with it? And in 10 years LM3875 probably won’t be the state of-the-art power amp chip. It is called a progress.

I referred to your claim that this chip was designed for the low end applications. Do you have a crystal ball that is telling you these things?

Pedja

[Peter Daniel]

Originally posted by janneman


Authority for what exactly?

Could it be for experience?

Seems like some members here are lacking in this department and they make up for this with a crystal ball.

[Pedja]

Originally posted by janneman


Authority for what exactly?

Jan Didden

I just can’t believe that I once understood seriously this guy’s questions.

Pedja

[millwood]

Originally posted by Pedja
I referred to your claim that this chip was designed for the low end applications. Do you have a crystal ball that is telling you these things?

Pedja

I certainly don't have a crystal ball for a claim that I didn't make. where did I state that the chip was designed for the low end applications?

On the other hand, we know that the chip is used in many low-end applications, like the alesis amp, the jbl active speakers, to list a couple.

Take a look at your mainstream high-end amp makers and tell us that the overture series is taking off like wild fires, using your crystal ball or not.

Now, the datasheet is a marketing tool and a technical document. Just because it says "high performance" doesn't means it delivers high performance and is not intended for low-end applications. I trust that those engineers at JBL know better about those chips than you and I.

[Peter Daniel]

Originally posted by millwood



Take a look at your mainstream high-end amp makers and tell us that the overture series is taking off like wild fires, using your crystal ball or not.

Now, the datasheet is a marketing tool and a technical document. Just because it says "high performance" doesn't means it delivers high performance and is not intended for low-end applications. I trust that those engineers at JBL know better about those chips than you and I.

With 3/4" front plate it has to be high-end: Bridgeclone - Rowland Concentraclone

[millwood]

Originally posted by Peter Daniel


With 3/4" front plate it has to be high-end:

Damn, I never thought "high-end" is measured in plate thickness. maybe manufacturers should state plate thickness rather than output power, distortion or sound quality for their high-end amps.