I don't see anything problematic, without seeing or remembering your exact schematic. VGND on C304 looks like there's just two small spokes connecting that lead, if that could easily be widened. Probably not consequential, though.
I have waded through the data and NP's document, but I would like somebody to stupid-ate this for my humble level of perceptions and thread wading laziness: this card can be operated from any DC voltage from 20 to 50 V as a front end without a problem, either single ended or dual pole? What are the ultimate DC voltage guard rails again?
I would stay under +48VDC single supply and under +/-24VDC dual supply. Mine sounds perfect at +/-20VDC.
Thank you. Would +36V single supply work? I suppose +20V single supply would be too low? What are the extreme operating conditions?
Hopefully Nelson could chime in and give us his thoughts. I would stay above 30VDC single supply and above +/-15VDC dual supply. Just my 2c worth.
Having discovered the 'teardrop' function in EasyEda (yours looks like KiCad?), that gives me a comfortable feeling (if nothing else) about the abutment of thin tracks into pads/vias, like this:
In his article Nelson wrote that the J113 and KSA992 have withstood 70V in testing, and suggested 50V as appropriate to allow the use of 2SK170 and other jfets.
I am in the middle of my build and since I am using the standard parts, I will be trying a 60V supply for a larger output voltage swing.
I am in the middle of my build and since I am using the standard parts, I will be trying a 60V supply for a larger output voltage swing.
So, does that mean that single ended voltage can be anywhere from 20V DC to 70V DC, depending on how much output voltage swing you want? What is the downward single ended limit?
20V total or +/-10V bipolar is probably too low even if you do not need the voltage swing, as that may be outside of the optimal operating point, resulting in much higher distortion.
As for unipolar or bipolar power supply, I don't believe that affects the preamplifier performance. I chose to go with single voltage so that I can go with a pseudo-mono power supply - each channel will have its own filter section.
As for unipolar or bipolar power supply, I don't believe that affects the preamplifier performance. I chose to go with single voltage so that I can go with a pseudo-mono power supply - each channel will have its own filter section.
In Spice at least, changing from +/-25V to +/-15V increases H2 by 3dB.
No changes in H3, etc.
Lowering further to +/-10V increases distortion by a further 3dB, so 6dB in total.
Patrick
No changes in H3, etc.
Lowering further to +/-10V increases distortion by a further 3dB, so 6dB in total.
Patrick
I'd say the FE 2022 is completely transparent without being sterile. Sometimes, when a design is very clean, it can unmask ugliness elsewhere... never happens with the FE 2022. It makes everyone get along and lets the VFETs shine and let them do what they do best. That this can be achieved with such an elegant and low-cost design is simply amazing! We are so lucky! It has not left the system since it went in 🙂
So, this means the H2 goes from appx. 100db down to 94db down @ +/- 10V versus 25V rails? Lower the V and spike the H2 a bit? Some people might like that, if that is what the Spice projection means?.
Anybody know when DIY store has another batch of kits coming in? I got on the email list. I think I am becoming slowly un-stupidated after looking at the card and NP's document. Signal output is 0+ and VG for ground if using with single voltage rail, input is IN+ to IN- with single voltage rail, R10 is shorted. It MIGHT work with higher distortion and lower swing @ 20V single rail but 30-60V single rail is recommended?
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Boards are overdue from DHL, and they will go right to the store. Takes the store a week or so
so get them processed.
These boards have a couple of additional features on the artwork - the original design is the base,
but a few more pads will give it some more flexibility.
After this shipment checks out, I will order a larger batch - there will be a an excellent supply.
so get them processed.
These boards have a couple of additional features on the artwork - the original design is the base,
but a few more pads will give it some more flexibility.
After this shipment checks out, I will order a larger batch - there will be a an excellent supply.