No-global-loop amplification

Simpelstark V1.3

Not quite done but now I have to go to work for a week.
These Simpelstark boards are quick and easy to set up.

I'll post impressions in a couple weeks. I'm very optimistic.;-)
 

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My Simpelstark+ V1.3

Hello All,

Here is my home build of Simpelstark.
More detailed post - in the Solid State Pics Thread.

I've got a fully dual mono configuration - separate transformers, separate PSUs, optocoupled protection.

Very happy about this build - I'm going to use it as my main amp at home for a while :)

Cheers,
Valery
 

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Hi Valery,
Nice measurements for a no global feedback amplifier !
What's the recommended rail voltage and transformer VA for 3-4 ohm speakers ?
Regards

Hi Danny,

Simpelstark V1.3 can drive 4 ohm speakers up to 160W as is.
However, if you need less power, it will feel more comfortable running at some lower rails voltage with those low-Z loads.

What kind of power rating do you have in mind?

Cheers,
Valery

P.S. Nice speakers by the way :up: :D
 
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Hi Valery,

They're about 93db sensitive.
I once tested my speakers and with 1.5V I get 91-92dbc at listening position.
I don't need the high voltage just more current.

I've just finished with a redesign of my speakers, with the new crossover they're now a little easier load, dip is 3.2ohm (100-200Hz)

I enjoy your threads about your different amplifiers, very nice concepts.

Regards,
Danny
 
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Maybe this article of 2017 is interesting.

Distorsion Reduction

More Distortion-Reduction & Taming the Triadtron

Luxman L-590A

Luxman%20L-590A%20Conceptual%20Overview%20from%20Audio%20Technology%20MJ%202005%20Issue%2011.jpg


The idea is quite similar to D. Bollen's scheme: a power amplifier's output is attenuated to match the input signal and the difference between these two signals is first inverted and then mixed with the input signal fed to the power amplifier, theoretically resulting in a large reduction in distortion. Here is the actual implementation from the review.

Luxman%20L-590A%20Schematic%20from%20Audio%20Technology%20MJ%202005%20Issue%2011.jpg


Distortion Reduction
 
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Luxman L-507 uXII

After reading this thread: I went from Class D to Luxman A/AB - And most of what you think is wrong | Audiogon Discussion Forum

I searched for info about Luxman 507

L-507uXII | INTEGRATED AMPLIFIERS | PRODUCTS | LUXMAN | Seeking higher sound quality

ODNF* Version 4.0 innovative amplification feedback circuit

pb2.jpg


An integral part of the design of the L-507uXII is LUXMAN’s original ODNF amplification feedback circuit. This features a fast-primary slew rate and an ultra-wide bandwidth that is achieved through the feedback of distortion components only from the amplification output circuit.

The latest version of ODNF–Version 4.0–is used, resulting in a dramatic enhancement of accuracy in distortion detection, lower impedance and a higher S/N ratio due to a parallel first stage and Darlington connected second stage of the amplification circuit, as well as a 3-parallel first stage error detection circuit.

A 3-parallel push-pull structure output stage achieves complete output linearity of 110W+110W (8Ω) and 210W+210W (4Ω). This type of circuit can achieve high power ratings that are comparable to a separate amplifier and has the force to drive various speaker systems to deliver high grade sound reproduction.

*ODNF stands for "Only Distortion Negative Feedback".
 
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