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Old 21st May 2018, 12:47 AM   #21
Pascal Nguyen is offline Pascal Nguyen  Australia
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Join Date: Sep 2016
Location: Sydney
Default Two figures from one source.

A little funny result from my Arta. It was taken at same settings.
At low resolution, my THD is 0.03%
At high resolution, 0.004%
If you like THD percentage, here they are
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File Type: jpg E9A5117E-6B00-4BFC-BFDB-1510BB86F3D3.jpg (705.3 KB, 243 views)
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Old 22nd May 2018, 08:34 AM   #22
Pascal Nguyen is offline Pascal Nguyen  Australia
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Location: Sydney
Default Mum, no 50Hz hum!

Quote:
Originally Posted by MossFed View Post

Second disappointment, 50Hz is -40dB at the output, it was reduced to -60dB with C-R add on (10mF and 2.7R)
Add-on another stage 10mF and 3.9R (because they are nearby, don’t know how to justify for values chosen), 50Hz dropped down to -74dB
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Old 22nd May 2018, 08:37 AM   #23
Pascal Nguyen is offline Pascal Nguyen  Australia
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Join Date: Sep 2016
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YouTube

I don’t have a 300B to experience with so I keep quiet, thanks for watching lengthy and boring posts.

Cheers and once more my gratitude to Mr K

Last edited by Pascal Nguyen; 22nd May 2018 at 08:44 AM. Reason: No editing at all, it was blank.
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Old 22nd May 2018, 12:42 PM   #24
padamiecki is offline padamiecki  Poland
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Hi Moss, keep posting on!
__________________
regards, Pawel
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Old 23rd May 2018, 10:55 AM   #25
Pascal Nguyen is offline Pascal Nguyen  Australia
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Quote:
Originally Posted by padamiecki View Post
Hi Moss, keep posting on!
Hi Pad,
I meant “quiet” for any comparison with 300B amp.
So far, one channel had been rat raced wiring, fortunately working well with an exception of excessive filtering at the driver circle that had to be added for lowering 50Hz ripple, will do some fiddling with the help of any “calculator on line” to work it out the correct RC values (My background is not related to EE). By the way I discovered that the phase of 9v coil is equally important in the ripple reduction, I swapped coil terminals to diodes bridge, miraculously I got another 12 dB ripple less to an agréable value of -88dB for 50Hz noise.
Photos included, please note at the red and blue wires go to the bridge and Arta FFT result (yellow and green).
The biases for my Lateral MOSFET are different from Mr K, due to mine is a 5 pins AllFet 08NP160.
Hope that I will finish the whole amp next week with a presentable pcb and casing.
Thanks for making this thread less monotonous to my monologue.

Cheers from Pascal
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Old 23rd May 2018, 11:20 AM   #26
kokoriantz is offline kokoriantz  Lebanon
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Join Date: Dec 2015
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Thank you MossFed for celebrating this amp. To make it comparable with Nelson Pass Nakamishi posted on YouTube ,can you record it with the same music found on YouTube , just for amazement. I'll post this weekend how to wind shielded secondary , it is very easy . You have done it wrong .
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Old 23rd May 2018, 11:35 AM   #27
Pascal Nguyen is offline Pascal Nguyen  Australia
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Join Date: Sep 2016
Location: Sydney
Default Nota Bene

The amp got his umbilical cord ectomy, it is running on a 50VA toroïdal transformer 240 / 18x2 / ES shield / 9.
ES shield is a must for a single transformer PS, it can be omitted if 9v is ressourced from another transformer (wall wart).
Now i am toying around with the odd and even harmonics by moving the window of biasing, looking for any sweet spot.
The amp is very stable, no pop at power on or off, thermal stability as well, due to lateral mosfets and clever design of driving stage, I mean circle.

Cheers
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Old 23rd May 2018, 11:39 AM   #28
Pascal Nguyen is offline Pascal Nguyen  Australia
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Quote:
Originally Posted by kokoriantz View Post
Thank you MossFed for celebrating this amp. To make it comparable with Nelson Pass Nakamishi posted on YouTube ,can you record it with the same music found on YouTube , just for amazement. I'll post this weekend how to wind shielded secondary , it is very easy . You have done it wrong .
Muchas gracias
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Old 25th May 2018, 01:02 PM   #29
kokoriantz is offline kokoriantz  Lebanon
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Default power supply

The power supply of bi-circleton requires a toroide transformer of 300VA 2x24V for each channel . The transformers need to be customized to 20V +20V(unloaded) +a shielded 9.9v (unloaded) of 160ma .

The transformer is put to naked , the center tap split , and equal number of windings taken off until required voltage achieved . By the same way the manufacture has treated the wires ,are retreaded again and the transformer locked back .

The shielded winding will dwell on the opposite side of the secondary wires ,two hours right of the primary entrence . The 9volt secondary to shield is merely 1.5VA that is a very small volume of cooper .

The following explanation will result , a 9.9volt (unloaded) secondary, having 5mm wide footprint wound in two layers, sandwiched between two cooper shields of open loop rings ,wide 15mm , harvested by a 600 ohm (two wires) coaxial microphone cable ,bringing the 9v shielded till the outer circle's pc board .

The wire has 160ma current ,the gauge table shows No 32 SWG or 30 AWG . The diametre is 0.275 mm. This is the minimum . Thicker will not be a problem except that when loaded the 9.9v will be higher than 9v , which the amp can accept without problem .

For the length ,first must know the voltage per turn that the transformer gives . Ten turns wound with any wire can provide precise value , it is between 0.25 to 0.3 volt/turn . Dividing 9.9v by this number gives the number of turns required to wind ,about 32 . Measuring the length of one turn on the donut ,about 17cm and the length of wire needed is fixed ,7m , by allowing some extra 10% gift . The whole wire is wound around a piece of cardboard about 15cm x4cm,with U shaped slots on each end , the ends of the wire are scraped and soldered for voltage measurements while winding .

The cooper foil is 15mm wide having a length just one turn precise . It is isolated by adhesive tape starting from the middle with single continuos band ,isolating also the edges . The shield is fixed on the donut with the endings inner side ,If it has a gap of one mm ,it is not a problem . On the left edge ,from the middle to 5mm downwards solder a thin wire, to end at the middle ,bend it leftwise ,cut it about 2cm long naked wire . Bring the wire to be wound about 5 cm long twisted with the shield wire and fix them temporarily with tape and start winding from left to right , As you are counting so that the lower layer has 4or 5 turn more than the upper one . Once the voltage is checked 9.9v then the arriving wire twists with its beginnig one and ends with same length . The coil is protected with adhesive tape . The coaxial cable of desired length gets its wires and shields exposed on both sides , because the wires can slide in the cable which will allow you to adjust precisely the length. The coaxial shield is separated into two brines , one is soldered along the width of the outer shield foil at the middle and comes on the coil with the cable on the right side , the inner shield's wire now is soldered to the upper's on the left bottom . The two winding wires first overcross the outer shield on a protected edge and go to the right entrance to greet their mates and come back together back to the left side, The coaxial wires are striped a generous 1 cm while the winding ones are scraped and soldered to be wound around the receivers ,soldered and isolated . A thick cardboard covering the wires and the shield solders is firmly adhered with tapes to serve as anchore to the recieving wires , which soldered tips are folded upon the cardboard acting as hooks , prventing the wires to be pulled. A last cooper shield is added isolated only underside, covering every thing bad looking and gets the second brine of the coaxial shield soldered diagonally on it, as the cable is now plied vertically . Done.

The power supply propsed bellow has mutual inductor . I tried it out using 12v/12v 48va isolator transformer , the result is spectacular dynamic sound . This small 50mh will fall about 1mh at 2x1.26A but it is sufficient . The 10000uF capacitors I chose, have a footprint of 18mm only ,which permits denser packing ,hence less inductive .
1pcs/37*22*15 50mH 1.0 Line 10A Annular filter Magnetic ring Common mode inductors Choke coi-in Inductors from Home Improvement on Aliexpress.com | Alibaba Group
20pcs/lot 25V 10000UF 18x35mm Aluminum Electrolytic Capacitors-in Circuits from Consumer Electronics on Aliexpress.com | Alibaba Group

I'll post in few ,a hand sketch proposition for pcb layouts for inner and outer circles .

Kokoriantz
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Old 25th May 2018, 01:13 PM   #30
kokoriantz is offline kokoriantz  Lebanon
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Join Date: Dec 2015
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MossFed , Your amp has Booing sound ,probably the transistors you are using need to be biased higher current . Try it between 1.6A to 1.8A . The bass must sound Paah not boo. Instead of 9volt higher it to 11volt. The two DNs must function at temperature about 50°C . The heat sink I use is just a sheet of U plied aluminum with shredded edges can install one TO220 inside and the other on the back . Yours is gigantic .
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