|
Home | Forums | Rules | Articles | diyAudio Store | Blogs | Gallery | Wiki | Register | Donations | FAQ | Calendar | Search | Today's Posts | Mark Forums Read | Search |
Solid State Talk all about solid state amplification. |
|
Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving |
![]() |
|
Thread Tools | Search this Thread |
![]() |
#1 |
diyAudio Member
Join Date: Dec 2004
Location: Tilburg
|
![]()
Hi, has anyone build or has expierience with the class A amps designed by Knutt Nygaard?
I was considdering building the current feedback design.Any comments would be welcome. |
![]() |
![]() |
#2 |
diyAudio Member
|
Hé Mènneke,
at 25 watt it is laid out for Tj= 80 C. The powersupply and heatsink cost a bundle: add two more 1216/2922 and the bias can go a lot higher with heatsink temperature at 55 C instead of 45 C., Tj =75 C. 4 times 2SA1216 or 2SC2922 go for 17 Euro at Schuro. With a few alterations the PCB layout of the elektor LMA50 can be used for 4 output transistors. Replace the wirewound by MPC71, at Schuro for 0.62 Euro or at Speaker en Co. ![]()
__________________
Why does it hurt when I Pee ? (Ay Ay Ay https://www.youtube.com/watch?v=w5fLGWrHouk) |
![]() |
![]() |
#3 |
R.I.P.
Join Date: Jul 2004
Location: Scottish Borders
|
Hi,
tell us more about MPC71. Advantages? Is Schuro the make or supplier? regards Andrew T. |
![]() |
![]() |
#4 |
diyAudio Member
|
Hi Andrew.
MPC71 is the name of the white block emitter resistor you see in japanese amplifiers for decades. It is a metalband resistor with low self inductance, unlike wirewound resistors. Not completely inductance free, resistors that are supposed to be are 10 times the price. MPC71 has a 5watt rating, MPC72 is 10 watt, made by Motorola. There is also a dual version, the MPC725, if space is limited. Like ring emitter transistors, MPC's are easilly available nowadays for $ 0.50 a piece, a DIY bloke like me had to travel half of Europe to buy them for five times as much in my early college days. I used to scavange broken japanese amps for these parts. (still do actually, the MPC725 i call Double Dutch ![]() Nygaard also uses ceramic caps in his designs. The ceramic caps i swapped for low cost styroflex capacitors. (i cherish my precious Siemens styroflex's ) I havent got a clue why some still use ceramic caps, other than that they are cheap caps in the pF range. Steve Bench did tests on capacitors, check out the curve for ceramic's.
__________________
Why does it hurt when I Pee ? (Ay Ay Ay https://www.youtube.com/watch?v=w5fLGWrHouk) |
![]() |
![]() |
Thread Tools | Search this Thread |
|
|
![]() |
||||
Thread | Thread Starter | Forum | Replies | Last Post |
1500W RMS Class D PCB - which Class D Driver Chip is it ? | mosfetsound | Class D | 11 | 1st April 2011 11:17 AM |
Can a Class AB PP amp be said to be operating in Class A at low signal levels? | ray_moth | Tubes / Valves | 19 | 23rd January 2009 07:52 PM |
How about a round-up of Class A kit power amps, or collectable vintage class A? | Brisso57 | Solid State | 4 | 14th February 2007 10:30 AM |
New To Site? | Need Help? |