SystemD LiteAmp

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#302
Ok. There seems to be vital interest regarding PCBs.

So I will go for a second buy. PCBs and NSL-32 only!
Please post here until Friday July 3rd the type (Mainboard or Gainboard) and how many pieces you wish to have.
In addition if neede please state if and how many NSL-32 you need.

Costs:
NSL-32: 0.88 EUR per piece
PCB for Mainboard: 2.43 EUR per piece
PCB for Gainboard: 1.99EUR per piece
Shipping inside Germany: 3.60EUR
Shippininginternational: 5.60 EUR
 
#306
ryk said:
2Χ every item make us a stereo amp? (I haven't read all the thread....yet!)
Click to expand...
It just makes the empty PCBs and Photocouplers for a stereo amp.
I am not offering completely assembled amp modules like it is common on ebay.
You will additionally need 2x all parts of the MainboardBOM, 2x all remaining parts of the GainboardBOM, 2x assembly work for the Gainboard, 2x assembly work for the Mainboard, 2x struggle through the real life get it going for the Mainboard, 2x struggle through the real life get it going for the Gainboard, + housing, connectors, power supply.

Besides reading the thread you definitely should check the BOMs in detail and see if you can get all parts .
And read through the assembly instructions and get it going section of the BOM-files, in order to see if you feel comfortable with all that.
 
#307
ChocoHolic said:
It just makes the empty PCBs and Photocouplers for a stereo amp.
I am not offering completely assembled amp modules like it is common on ebay.
You will additionally need 2x all parts of the MainboardBOM, 2x all remaining parts of the GainboardBOM, 2x assembly work for the Gainboard, 2x assembly work for the Mainboard, 2x struggle through the real life get it going for the Mainboard, 2x struggle through the real life get it going for the Gainboard, + housing, connectors, power supply.

Besides reading the thread you definitely should check the BOMs in detail and see if you can get all parts .
And read through the assembly instructions and get it going section of the BOM-files, in order to see if you feel comfortable with all that.
Click to expand...

Understood! I have seen the boards, I was just asking to make sure what should i need for a stereo amp.I am planning on order from farnell everything i need. Some things i have them already, i will ask when time comes (e.g. opamps). Only scary part is the 360ΚHz tuning, since i don't have an oscillograph, but i will think of something, someone might help me out.

So, 4x every board (for 2 amps).
 
#310
ryk:
2 pcs of the main boards
2 pcs of the gain boards

Optional, in case you want to implement the limiter functionality on the gain board:
2 pcs NSL-32

Cresnet:
PCBs and NSL Like for ryk.
Sorry, no PCBs on stock. I will order them after the running collection of requests is finished.

Siankovic:
😉 alright
10 pcs of the main boards
10 pcs of the gain boards
10 pcs NSL-32

@all:
Please send your shipping adress by PM, I will then give you my paypal data for easy payment.
Also possible to pay by bank transfer, please let me know.
 
#312
The power amp on the mainboard needs large input signals.
Voltage gain is factor 4.9.
Consequently you need large input signal, in order to reach clipping an input signal of roughly 8Vp into 5.5 kOhms is needed.
The gainboard is providing the necessary gain to be driven by line level signals and also provides symmetric inputs with high input impedance.
The gainboard also offers the option to implement a limiter (NSL-32 + TL074 with all the stuff around the TL074).

Instead of the gain board you can of course use an existing pre amp (if it can drive 8Vp into few kilo ohms) or your own custom design gain stage.
 
#318
ryk said:
ryk:
Is there a way for the Limiter to be switched on-off?
Is it advisable to have it always on?
Click to expand...

The limiter influences the signal chain only by the NSL-32.
The TL074 is only used to measure the output level and forming proper limiter attack and release behavior. TL074 is not in the signal path.
When playing below 90% of clipping level, the NSL shows only its dark resistance and the introduced errors are neglectible.
Please refer to posting #160.
Neglectible at least in terms of measurements, I did not go for extensive listening comparisons without limiter vs with limiter.
Theoretically you can disconnect both resistor terminals of the NSL by a dual switch. Personally I guess the related wiring will add more harm (i.e. hum) rather than improving things. Nevertheless it is a possible mod.
Of course you can also assemble the gain board without limiter at all.

Scope:
If you cannot measure the oscillation frequency, then it is advisable to substitute the pot by a fixed 100 Ohms resistor.
In general the absence of a scope will make if more difficult to search errors. Remember the build from Reactance, thanks to his screen shots it was possible to narrow down the search to the area of the feedback and loop gain network. Reactance then pretty fast found the wrong feedback resistor. Without a scope, it would have been much more difficult.
 
#320
😱😱
...pretty unexpected amounts 🙂

I am collecting your orders.
In order to make sure that everybody is in - I will post a consolidation list after the collection phase is over. So you can double check if I got everything right.
Few days later I will order the PCBs.
Of course private details like adress and money transfer remain backstage.
 
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