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Simpelstark+ ODNF amplifier boards GB

The BOM in Excel is HERE.

Please make your order via the web store at:

Simpelstark GB - Virtual Zero Audio Store

The reason I'm asking to do it that way - our shipping process is pretty much automated with the tools in the store, plus you will be able to specify the address and choose the preferred delivery method for your convenience.

Please put the desired products to the shopping cart, adjust the quantity if required, and proceed to checkout.

Please let me know if you will have some questions / need assistance with the process.

Cheers,
Valery

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ORIGINAL MESSAGE ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Simpelstark+ ODNF V1.3 is one of my favorite amplifiers, providing unprecedented sound quality at a wide range of listening volumes, from low volume ambient background to high-power focused listening. The amplifier is greatly appreciated by a number of DIY enthusiasts around the globe.

For more details about the design specialties and detailed characteristics please see the attached datasheet.

GB is available for 3 kinds of a bundle:


1) 2 x Simpelstark amplifier PCBs ($26.18)

00_Bundle_0.png



2) 2 x Simpelstark amplifier + 2 x Compact PSU PCBs ($49.43)

00_Bundle_1.png



3) 2 x Simpelstark amplifier + 2 x Compact PSU + Amp Control System V6.2.2 (full set of 5 boards) PCBs ($69.68)

00_Bundle_2.png



Build Guides and technical support during the build will be available as usual.

The prices are shown for the case of reaching the quantity of around 50 bundles.
Orders will be taken via the Virtual Zero Audio Store. Shipping options will be available at checkout - normally it's around $15 for the most of international locations unless you choose some expedited delivery option.

Please express your interest here in the thread. I will open a special discount for placing the orders as soon as we get enough participants.
Don't hesitate to ask questions.

Cheers,
Valery
 

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Last edited:
Founder of XSA-Labs
Joined 2012
Paid Member
Hi Valery,

That’s a nice looking harmonic profile!

774590d1565637380-simpelstark-odnf-amplifier-boards-gb-03-01khz-jpg


Is there a thread or post somewhere explaining the “Only Distortion Negative Feedback” ODNF concept - with schematic? It sounds really interesting.

I have too many amp projects in the queue already, otherwise would probably sign up for this.

Cheers,
X
 
Last edited:
Hi Valery,

That’s a nice looking harmonic profile!

774590d1565637380-simpelstark-odnf-amplifier-boards-gb-03-01khz-jpg


Is there a thread or post somewhere explaining the “Only Distortion Negative Feedback” ODNF concept - with schematic? It sounds really interesting.

I have too many amp projects in the queue already, otherwise would probably sign up for this.

Cheers,
X

Hi X!

Here is the initial thread:
No-global-loop amplification

Here is the post with some theory:
https://www.diyaudio.com/forums/solid-state/312866-global-loop-amplification-16.html#post5328425

Simpelstark V1.1 post:
https://www.diyaudio.com/forums/solid-state/312866-global-loop-amplification-18.html#post5347597

Very good discussion with Brian (traderbam) and Hugh (in the background) helped a lot to clarify my own understanding of what really happens in ODNF setup.

Version 1.1 was tested very successfully, however, later on, I introduced some further improvements in the output stage - current version is V1.3 (you can see the building guide with schematic in the store, being logged in).

The key idea - design an amplifier as linear as you can, having no global loop at all, providing the gain you need (e.g. 29db), and then add 18-20db of ODNF (overall gain will not change).

This is the very promising approach - I continue working on some pretty cool new designs, based on it.
If you will have some questions - please let me know.

Cheers,
Valery
 
Last edited:
I am very interested in 1 x (2), but have a question please - what toroids are needed here?

Hi Twocents,

You can take this one as a "template":
AS-3435 - 300VA 35V Transformer - AnTek Products Corp

Power rating you need for the best performance is around 150-200VA per channel. 300VA one is fine assuming you still use 2 x PSU modules (1 per channel). The secondary voltage you need is 2 x 35...36V.

Cheers,
Valery
 
Founder of XSA-Labs
Joined 2012
Paid Member
One note regarding toroidal power supplies is that using a single big one (300VA) with two CRC boards may tend to have ground loop hum. Quietest way is to have dual smaller trafos and dual CRCs. Use star grounding and isolate dirty Earth/chassis ground from clean 0v common power/analog ground with an NTC (CL60 etc) 22nF film cap.

The loop comes from the SE source input which usually has a common ground and that will tie the two grounds together causing hum.
 
One note regarding toroidal power supplies is that using a single big one (300VA) with two CRC boards may tend to have ground loop hum. Quietest way is to have dual smaller trafos and dual CRCs. Use star grounding and isolate dirty Earth/chassis ground from clean 0v common power/analog ground with an NTC (CL60 etc) 22nF film cap.

The loop comes from the SE source input which usually has a common ground and that will tie the two grounds together causing hum.

Thank you, X - a very valid comment.

In my prototype build, I used 2 x 200 VA transformers - having a true dual-mono as a result.

In case of a single transformer, star ground or T ground approaches show good results.