This is ONLY a cosmetic upate.
The conversion software from dxf to Gerber caused a slight misaglinment in the Title text.
This is now manually realigned.
No change in the circuitry, so Version 2 is still fully functional.
Patrick
.
The conversion software from dxf to Gerber caused a slight misaglinment in the Title text.
This is now manually realigned.
No change in the circuitry, so Version 2 is still fully functional.
Patrick
.
Smalll Question...
does somebody try and test Tokin VFET (SIT) 2SK182 2SK182ES
stock is > 5000 pcs. only by 1 supplier
different supplier have > 2000 and > 3000 pcs. stock
I don't believe that VFET (SIT) is not newly produced by a small manufacturer in China, 41 years after the end of production the quantities available for purchase are too large and everything looks like new. Many obsolete Japan transistors for example Toshiba 2sc2240 2sa970 Sanyo 2sc3503 2sc2655 ...
are now newly produced in China by a small unknown factory.
According to customer requirements, a transistor, for example 2sc2240, can also be produced with an interchanged PIN BCE order, so I believe that the VFET SIT, such as Tokin 2sk182, will be produced again somewhere in China
does somebody try and test Tokin VFET (SIT) 2SK182 2SK182ES
stock is > 5000 pcs. only by 1 supplier
different supplier have > 2000 and > 3000 pcs. stock
I don't believe that VFET (SIT) is not newly produced by a small manufacturer in China, 41 years after the end of production the quantities available for purchase are too large and everything looks like new. Many obsolete Japan transistors for example Toshiba 2sc2240 2sa970 Sanyo 2sc3503 2sc2655 ...
are now newly produced in China by a small unknown factory.
According to customer requirements, a transistor, for example 2sc2240, can also be produced with an interchanged PIN BCE order, so I believe that the VFET SIT, such as Tokin 2sk182, will be produced again somewhere in China
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> What is the value of the Bourns 3296X?
Depends on the Idss of your J113.
You can use a breadboare and some fixed resistors to get close to 10mA by trial & error.
That will tell you what value of Rdg you need.
I think Morde used 270R (SMD) // 2k trimmer.
Patrick
Depends on the Idss of your J113.
You can use a breadboare and some fixed resistors to get close to 10mA by trial & error.
That will tell you what value of Rdg you need.
I think Morde used 270R (SMD) // 2k trimmer.
Patrick
With a Vgs=1,4V @3mA for the Q1(J113) I managed to set the offset with 500R trimmer in parallel with 270R SMD resistor on the PCB.
Yes, it was just an example of one of my highest Idss J113 devices that was measured @3mA. According to datasheets and some rough extrapolation the Idss is somewhere around 25-30. 🙂
I managed to get both channels up and running with the new matched FQA mosfets. Rail voltages were +-21,7V with the First Watt type of CRC supply and 300VA/2x18V transformer. Bias was stable over one hour 1,35A for left and 1,36A for right. DC offsets were easily settable to few mV without servo.
Some listening impressions:
I had my Ian Canada dual ESS9038 DAC feeding the amp directly. Music was flac files ripped from CDs and also a couple of high-res files 24bit/96/192kHz played with Moode software on a RPi 2. I compared the UDNeSS against my Denon AVR-X3000 amp and Volume levels were matched using DMM and 1kHz sine wave. My speakers are Phonar Veritas P6 Next (4ohm, 87dB/W).
Bass control/separation is still the biggest culprit with my 4ohm speakers, but there has been some positive development since the first proto iteration. Very small difference to my Denon AVR-X3000. Bass depth is very good.
Vocals is where the UDNeSS really shines. Very good presence, details and musical feeling that gives you goosebumps.
Tweeter section was also somewhat smoother and more pleasant than the Denon.
Sound stage has improved since the last listening session with the earlier proto and is on par or better now than Denon.
Overall the UDNeSS has a bit warmer and more pleasant sound and it shines with acoustic/lighter/vocal music.
I would dare to say that this is really good value for money with easy-to-get parts and if you happen to have speakers with higher impedance/sensitivity it will shine even more. I’m a happy camper even with my present speakers. 🙂
Some listening impressions:
I had my Ian Canada dual ESS9038 DAC feeding the amp directly. Music was flac files ripped from CDs and also a couple of high-res files 24bit/96/192kHz played with Moode software on a RPi 2. I compared the UDNeSS against my Denon AVR-X3000 amp and Volume levels were matched using DMM and 1kHz sine wave. My speakers are Phonar Veritas P6 Next (4ohm, 87dB/W).
Bass control/separation is still the biggest culprit with my 4ohm speakers, but there has been some positive development since the first proto iteration. Very small difference to my Denon AVR-X3000. Bass depth is very good.
Vocals is where the UDNeSS really shines. Very good presence, details and musical feeling that gives you goosebumps.
Tweeter section was also somewhat smoother and more pleasant than the Denon.
Sound stage has improved since the last listening session with the earlier proto and is on par or better now than Denon.
Overall the UDNeSS has a bit warmer and more pleasant sound and it shines with acoustic/lighter/vocal music.
I would dare to say that this is really good value for money with easy-to-get parts and if you happen to have speakers with higher impedance/sensitivity it will shine even more. I’m a happy camper even with my present speakers. 🙂
Good point. I ordered 10 pieces of FQAs. I recommend to get some more because the two pairs was all I got out of ten.
So this amp can easily be responsible for the top end (high and mid) and paired with a slightly more powerful class AB for the lows in a bi- or tri amping system 🙂
Yes, e.g. you can use 2x LM3886 in parallel for the bass.
But you still want 6~8-ohm speakers for the tweeter & mid-range.
Patrick
But you still want 6~8-ohm speakers for the tweeter & mid-range.
Patrick
^
Got it. I still need to read the links your provided, me has ben busy. It will take a few months before I can dedicate myself to building this one, but that is okay.
Got it. I still need to read the links your provided, me has ben busy. It will take a few months before I can dedicate myself to building this one, but that is okay.
Just saying...
If a matched semi package were sold I would build this design overnight!
I already have a matched quad of 2SK170BL's for Q2,Q3 but need to read up on measuring JFETs like J113 for Q1 (to find one that has a minimum Idss of 8.5mA and since it dictates what value Bourns 3296 pot needs to be purchased for the Rdg component), as well as MOSFET matching and testing, for Q4, Q5 which require matching Vgs at bias between channels.
Ti Kan has a nice web page describing how matching of different semis can be done:
The β22 stereo amplifier
How many J113's should be purchased to find one that has at least an Idss of 8.5mA?
Morde, you recommend ~ 20 FQA9P25's perhaps to find at least 1 QUAD to match?
Best,
Anand.
If a matched semi package were sold I would build this design overnight!
I already have a matched quad of 2SK170BL's for Q2,Q3 but need to read up on measuring JFETs like J113 for Q1 (to find one that has a minimum Idss of 8.5mA and since it dictates what value Bourns 3296 pot needs to be purchased for the Rdg component), as well as MOSFET matching and testing, for Q4, Q5 which require matching Vgs at bias between channels.
Ti Kan has a nice web page describing how matching of different semis can be done:
The β22 stereo amplifier
How many J113's should be purchased to find one that has at least an Idss of 8.5mA?
Morde, you recommend ~ 20 FQA9P25's perhaps to find at least 1 QUAD to match?
Best,
Anand.
Best to find some other builders and group match.
A larger pool will give better yield, and costs less in the end than each matching his own.
Patrick
A larger pool will give better yield, and costs less in the end than each matching his own.
Patrick