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First One - mosFET amplifier module

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Lazy Cat

Lazy Cat

Member
Joined 2007
Look Mark this is trivial, XLR is balanced output and can be floating, isolated from GND, but when we want RCA output, negative phase of transformer's secondary winding should be connected to DAC analog GND and not be floating anymore. Obviously this GND is not present on XLR, so it should be made separately. I cannot help you from here on since I don't know the sch, but any basic DIY-er could find analog GND reference point inside your DAC.
This is an issue only with transformer's output, opamp DAC outputs XLR or RCA have analog GND (GND from analog PSU) present on their pins, like Benchmark DAC-s etc. To solve your problem, 3 min job.
 
M

Mark Verhoeven

Member
Joined 2009
Andrej,

I understand, so what AudioNote is doing for XLR is fine, but their connection to RCA isn't exactly the way it supposed to be.

As you describe, for decent RCA function, it's needed to connect negative phase of transformer's secondary wiring to DAC analog ground. That's no problem for me to do, as I have schematic.

Let's look at this picture (most left) as that looks like my output transformer:

Fig-11-4-2.gif


A = Positive Phase, I do connect that to RCA center pin
B = Negative Phase, I do connect that to analog ground
CT needs to be connected to RCA ground???

Do I also need to connect CT to analog ground?
 
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Lazy Cat

Lazy Cat

Member
Joined 2007
I'll certainly need few weeks to perform PCB artwork to the highest level possible as new v1.4 incorporates almost 40 semiconductors. PCB dimensions and fixing holes will stay exactly the same so v1.4 will be direct replacement to v1.2, one hour to swap both channels to the new version.
Stay alert, high resolution First One v1.4 is coming soon. :yes:
 
H

hose4

Member
Joined 2013
Lazy Cat said:
Naim SuperUniti as a source, First One amplifier (final version) and Thiel CS3.7 loudspeakers, that's all what you need, pure High End :cloud9:

Green light for production is ON. :wiz:
Click to expand...

I agree. The sound is clean and clear. Music is communicative. I still cannot believe SuperUniti as s streamer/preamp is so good as a preamp. Very neutral.

Listening to FO1.3 and FO1.4 shows quite big differences. Both have very good resolution.

To my taste FO1.3 is warmer in sound. It is looser in the bass department and has less spectral information in treble region.

FO1.4 just sounds clean and clear. It is very neutral in the whole spectrum has very good resolution. Main and background sounds are easy to follow. Does not compress when the music gets complex. To whatever we listened during Sunday session was always enjoyable. It does not draw attention to itself.
 
Lazy Cat

Lazy Cat

Member
Joined 2007
pinnocchio said:
Hi LC,

Would be great if you would sell blank PCBs and a BoM for those like me who really enjoy soldering SMD components. Makes it more DIY..

I know i might be dreaming but it would be great :D

Ciao!
Do
Click to expand...

Hi Dominic

First One v1.4 will simply be too complex for domestic SMD assembly, take my word and please comment after presentation, would really like to hear your opinion afterwards. :)

Also there will be some news regarding modules differentiation as follows:

- First One v1.4 S (small - ex. VSSA) - 100 W/4 ohm
- First One v1.4 M (medium) - 200 W/4 ohm
- First One v1.4 L (large) - 400 W/4 ohm

First One release will of course be presented in medium size. ;)

Before official launch, as usually, First One v1.2 is available from the stock.

Stay tuned, regards L.C. :wave:
 
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