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Chip Amps Amplifiers based on integrated circuits

Using chip amp like Hafler transnova ?
Using chip amp like Hafler transnova ?
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Old 21st April 2015, 12:03 PM   #1
UltimateX86 is offline UltimateX86  France
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Default Using chip amp like Hafler transnova ?

hello,

Do you think it is possible to made a chip amp power amplifier based on the transnova schematic ? (floating power supply)

thanks
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Old 22nd April 2015, 11:04 AM   #2
bentsnake is offline bentsnake
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I can't imagine why not. With a quick look at the schematic it's just some NE5532s (very widely used) hooked to some power output transistors.

However, speaking frankly, if you have to ask the question, then the answer is no. The Transnova is large and complicated, which means many chances for error. This invokes the first law of dynamics: if something can go wrong, it will.

On the other hand, what do I know? Maybe you can knock the thing out in 20 minutes, right every time. I can't prove otherwise.

Still, if you're new at this little-black-chip stuff you might be better off with something a bit more straightforward. You might consider, maybe, a 20-watt LM1875 amp, which is more like what chip amps are all about.

The circuit given on page 2 of the data sheet would serve you well. Notice that in the shown circuit pins 3 and 5 are for power, the audio circuit is really quite simple as such things go. The data sheet is here: http://www.ti.com/lit/gpn/lm1875
.
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Old 23rd April 2015, 01:35 PM   #3
geraldfryjr is offline geraldfryjr  United States
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The Hafler Transnova was a Discrete Transistor design.
I don't really see this happening, the local feedback was a method of using several points along the stages of the circuitry combined together to form the final negative feedback signal.
You can't get inside of a chipamp to implement this.

FWIW

jer
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Old 23rd April 2015, 02:55 PM   #4
forr is offline forr  France
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Quote:
Originally Posted by geraldfryjr View Post
The Hafler Transnova was a Discrete Transistor design.
I don't really see this happening, the local feedback was a method of using several points along the stages of the circuitry combined together to form the final negative feedback signal.
You can't get inside of a chipamp to implement this.
You may refer to the intial Acoustat Trans-Nova amp circuit (US patent #4467288 by James Strickland) which, according to the author, uses an error feedback scheme.

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Source : COSTRUIRE HIFI :: Leggi argomento - acoustat transnova twin 200 info

I think Trans-Nova initially refered to the transresistance output stage, the current through Ra in the patent defining its voltage gain.
The Hafler Trans-Nova (9300, 9500 in 1991, P1500, P3000 of nineties) were also conceived by Strickland and based on the same idea.

Click the image to open in full size.

UltimateX86 only thinks of a floating power supply which is not specific to only one manufacturer, however the Acoustat schematics was the first I saw to have one.

More recently ATC, QSC and Behringer, I think, use floating power supplies.
The scheme was mentioned in an article about power amps published AudioXpress some years ago.

The most recent published amp (two weeks ago !) having a floating power can be found here : volumes | Linear Audio ,
preview --> A Low Parts Count Audiophile Power Amplifier

With a floating power supply, the + and - power supply pins of a chip power amp will see almost the varying voltage across the load.

However, some little chip can have the output boosted by power transistors, and may present a possibility of a floating power supply for the output stage.

Last edited by forr; 23rd April 2015 at 03:16 PM.
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Old 23rd April 2015, 11:33 PM   #5
geraldfryjr is offline geraldfryjr  United States
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Ohh Okay, Yes, I guess I was thinking differently from what I had remembered from an article in magazine back in the late 70's and they had published the schematic as well.

The only thing that they were going on about in the article was the method of the feedback system, I don't remember if and how much they described the power supply situation.

To me it didn't look like anything special at all when you think about it and trace the current paths.

The Sunn Concert Power amplifier has a similar configuration only it is a BTL output stage.

There has been a few different discussion about this type of setup in these threads a while back and here is one that I do remember well,

QSC audio - floating supply amplifiers

Sorry for the confusion.

I stand corrected, Yes I think that this could be done with a chip amp, I wasn't thinking about the floating supply I just remembered some of the details of the feedback network as it was described in the article I saw some 30/40 years ago !! He,he,he,he

jer
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Old 24th April 2015, 12:24 AM   #6
tomchr is offline tomchr  Canada
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The schematic looks like a pretty standard MOS output amp. Seems like a job for an LME49830.

Tom
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