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Chip Amps Amplifiers based on integrated circuits

Linn Chakra power amps revealed ...
Linn Chakra power amps revealed ...
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Old 22nd March 2011, 05:14 PM   #1
jo987 is offline jo987  Germany
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Talking Linn Chakra power amps revealed ...

yes I have read some posts/threads about Linn chip amps.
But, having been thinking about the Chakra patent for the last couple of months
I thought it might be interesting to share my ideas and get some answers from the experts.

The idea is to "reveal" the Linn Chakra schematics.
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Old 22nd March 2011, 05:34 PM   #2
tinitus is offline tinitus  Europe
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Linn Chakra power amps revealed ...
well, if you 'redraw' it with your 'own hand', no problem
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Old 22nd March 2011, 08:04 PM   #3
alexcp is online now alexcp  United States
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Linn Chakra power amps revealed ...
From LINN's whitepaper:

Monolithic technology is used extensively throughout Linn’s product range, both as single chips and paralleled devices to increase power output. The CHAKRA topology is the result of more than 5 years of continuous development of Linn’s high-power monolithic amplifier audio circuits, and was initially conceived during development work for the Linn 328A professional monitoring loudspeaker. The Linn 328A required greater power, circuit density and performance than even our reference monolithic power amplifier, the KLIMAX 500 Twin, could offer, and so we began work on developing a solution which performed accurately and consistently in even the most demanding monitoring applications.

The CHAKRA topology we devised uses an array of large bi-polar transistors as ‘boosters’ around a single monolithic. This approach in itself is not a new idea, but Linn’s execution of the monolithic to bi-polar transition is truly unique, and a patent application for the design has been submitted. When output current is less than a few amps, all of the power output comes from the monolithic, maximising the speed and linear properties of this design. At higher output currents the bi-polars provide the majority of the output current, leaving the monolithic to operate well within its capability and so able to correct any error instantaneously. Even under extreme overload conditions, like short circuit, the monolithic never delivers more than a fraction of its safe output, while separate circuitry protects the bi-polars. So with current output virtually unlimited, CHAKRA offers robust and powerful low-frequency response down to near DC. This is essential for the type of servo-controlled bass systems used throughout Linn’s highest performance loudspeaker systems and benefits will extend across all future iterations and applications of the CHAKRA topology. The new topology is also very compact, actually reducing the circuit area and signal path length compared to our previous best paralleled topology and it is also highly efficient, running cooler than any previous Linn amplifier design.

While the new CHAKRA topology represents a massive step forward in Linn’s direct signal path circuitry, the overall performance of a power amplifier is equally dependent on its power supply. Linn’s compact proprietary, audio-optimised Switch Mode Power Supply (SMPS) technology generates stable, low noise power rails for the audio circuitry, with higher mains noise isolation and efficiency than the very bulky and noisy conventional power supplies. The combination of SMPS and CHAKRA technologies creates a wealth of possibilities for new configurations of high-performance, high-efficiency Silent Power amplifiers.

A key design consideration during development of the CHAKRA audio circuit technology was the ability to power loudspeakers in internally or externally active configurations. As a result, active modules can plug directly into the main CHAKRA amplifier for straightforward active system building. Each of these active modules filters the signal for one drive unit, with a separate module allowing simple and subtle optimisation of the system to suit the room, aiding the simple installation of active systems and optimising performance.

The Linn CHAKRA technology eliminates the weaknesses and maximises the strengths of monolithic linear amplifier technology. It combines the speed and precision of a high integration chip technology with the ruggedness and smoothness of discrete ultra-linear bipolar transistors and delivers precisely controlled Linn Silent Power at all listening levels.
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Old 23rd March 2011, 02:07 AM   #4
Gopher is offline Gopher  United Kingdom
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Sounds just like yer typical Class B current boosted opamp circuit that you can find in just about any electronics textbook.

Amazing how you can make something so common and simple sound so fancy.
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Old 10th April 2011, 03:27 AM   #5
jo987 is offline jo987  Germany
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If you look at the patent schematics (upload of the pictures wasn't successful, I will upload them later), there is something new about the circuit.
They have added some inductors "for axtending a switching off period of the second amp (with the bipolars) to smooth any switching discontinuity", as the patent says.
When you look at fotos of the Linn amps (i.e. C2200,Klimax Chakra 500) you will notice the
inducters close to the bipolar transistors.
That's the new circuit by Linn.
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Old 10th April 2011, 03:29 AM   #6
jo987 is offline jo987  Germany
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Here are the two pictures of the patent and of a c2200.
Attached Images
File Type: jpg linnchakrapatent01.jpg (56.3 KB, 2092 views)
File Type: jpg linnc2200amp01.jpg (150.7 KB, 2075 views)
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Old 10th April 2011, 04:20 PM   #7
jo987 is offline jo987  Germany
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Default Klimax Chakra 500 Twin

Here is a picture of the Klimax Chakra 500 TWIN prototype.
My suggestions for the marked areas are:
A. Bipolas with "Chakra" inductors (obvious)
B. OpAmp for ??? (most likely a DC-servo ? in the feedback path), you will find this in every Linn amp with Chakra circuit.
C. Sense resistors. Most likely sensing the V+ and V- current through the TDA and the bipolars. As the manual of the klimax tells us, the amp will monitor the current and will turn-off the amp in case of ultra high current. You will find this also in all Linn amps.
D. Boucherot network
E. A pair of diodes to minimize inductive backloads.
F. Most likely a quad OP-AMP. But what for ? The Klimax senses the input and turns-on when the audio input is >100ÁV. This quad could do this and at the same time acts as an input buffer (?).
G. This is R1 in the patent circuit.

Any other suggestions ??
Ideas and questions welcome.
Attached Images
File Type: jpg Klimax_Twin_Chakra.jpg (58.6 KB, 1988 views)
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Old 12th April 2011, 04:04 PM   #8
jo987 is offline jo987  Germany
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Here is another foto with higher resolution I found in a magazine.
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File Type: jpg Chakra-500-Twin-01.jpg (181.3 KB, 1905 views)
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Old 2nd May 2011, 03:56 PM   #9
jo987 is offline jo987  Germany
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Cool First Schematics

This my idea of simplified schematics for the Chakra circuit.
1. 1st stage as input buffer and low pass filter
2. TDA with OPamp in feedback path as DC offset servo (I have seen this a couple of years ago in a Burmester 878).
3. The Chakra stage withe the bipolars and the inductors.
4. The output shows the boucherot and the protector diodes.

Any mor suggestions on this ?

Kind regards
Attached Files
File Type: pdf Linn_Chakra_Concept.pdf (188.4 KB, 742 views)
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Old 7th May 2011, 01:27 PM   #10
Dag is offline Dag  Sweden
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I think the bipolars are placed differently, see http://www.diyaudio.com/forums/chip-...tml#post582631
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