with 2pr counterfeit transistors. Yeah, right....
http://cgi.ebay.com/ws/eBayISAPI.dl...MEWA:IT&viewitem=&item=220062422472&rd=1&rd=1
http://cgi.ebay.com/ws/eBayISAPI.dl...MEWA:IT&viewitem=&item=220062422472&rd=1&rd=1
If you could get it to run on ±47V without blowing up, it might put out 60W/8R per channel. The heatsink looks like a very poor design. No sign of thermal tracking for the bias.
I used to look at junk like this from MK V Audio and wonder why they went to all the trouble to kit up something that had a poor design (at best).
Some of the kits from Dick Smith (AU) weren't much better.
I used to look at junk like this from MK V Audio and wonder why they went to all the trouble to kit up something that had a poor design (at best).
Some of the kits from Dick Smith (AU) weren't much better.
and the PCB says "AC 20-26V"
Hi,
the 1943/5200 running on low supply rails perform very well.
4pair are capable of 350W into 2r with a load phase angle of 40degrees and yet stay with the DC SOAR 35degC.
Increasing the load phase angle to 60degrees just takes the 4pair to the 100mS SOAR.
Pulsed operation into 1.2r would just about hit 500W.
All this from +-48Vdc.
From +-38Vdc (26Vac) well that takes some believing.
But if you were talking peak power into 1r2, that needs just 24.5Vpk and even less into 1r0.
the 1943/5200 running on low supply rails perform very well.
4pair are capable of 350W into 2r with a load phase angle of 40degrees and yet stay with the DC SOAR 35degC.
Increasing the load phase angle to 60degrees just takes the 4pair to the 100mS SOAR.
Pulsed operation into 1.2r would just about hit 500W.
All this from +-48Vdc.
From +-38Vdc (26Vac) well that takes some believing.
But if you were talking peak power into 1r2, that needs just 24.5Vpk and even less into 1r0.
Re: Re: 500 WPC on 24v for $69
If I may say, I have found a slightly less expensive way to play with some nice stuff.
I have learned a lot recently by buying three 1980's vintage amplifiers on eBay, for relatively modest sums, and studying their schematics:
1) A Marantz PM450 2 x 60W amplifier, bought for 31 euros and I had to pick it up in Paris. The switches and potentiometers needed lubrication and the inside was extremely dirty, but all in all it was in very good shape. It uses 2 x 6800uF/50V caps in the PS. What I like best in this amplifier is the strict adherence to the KISS principle. I could understand the entire circuit very easily, and everything makes sense.
2) A Luxman LV-111 2 x 50W amplifier, "not working, sold as-is", bought for 33 euros including shipping. It too uses 2 x 6800uF/50V caps in the PS, one of the capacitors had its top off. Replaced the capacitor and a fuse and it's working. Externally it is in mint condition. I admire the work of the production engineers who laid out this amplifier, it is extremely neat and orderly inside. Funny they used a Sanyo STK chip to drive external power transistors.
3) A Yamaha A-760 2 x 80W amplifier "burned, sold as-is", bought for 15 euros delivered. This one uses 4 x 6800uF/63V capacitors. It really had a Rifa RFI capacitor that had exploded, a blown fuse and a small lamp that had burned, which I replaced with a white LED. I somehow managed to find the service manual on the Web and studying this amplifier's relatively complex circuit has been very instructive and enjoyable.
I am fascinated by the "no-nonsense" design decisions of the engineers who designed these three amplifiers (except perhaps the Yamaha that used a daring "X" Power supply configuration). All three date from more or less the same period (early 80's ) and use bipolar power transistors in class AB configuration. They all sound very good (to me, at least), unfortunately I don't have the equipment to measure distortion, SNR, bandwidth and other parameters (I have a Tektronix 2225 oscilloscope and a multimeter, that's all).
I am looking forward to finding a MOSFET-based power amp for not too much and trying to understand it, and the decisions that were made by the people who designed them.
However I confess I don't feel very enthusiastic about the amplifier that was at the origin of this thread. It sold for $77 + $18 shipping and when I think about it that's more or less what I spent for the three amplifiers I bought, with case, transformer, potentiometers, etc.
Merry Xmas to you guys, I enjoy very much reading your posts.
Hi,lineup said:
If I may say, I have found a slightly less expensive way to play with some nice stuff.
I have learned a lot recently by buying three 1980's vintage amplifiers on eBay, for relatively modest sums, and studying their schematics:
1) A Marantz PM450 2 x 60W amplifier, bought for 31 euros and I had to pick it up in Paris. The switches and potentiometers needed lubrication and the inside was extremely dirty, but all in all it was in very good shape. It uses 2 x 6800uF/50V caps in the PS. What I like best in this amplifier is the strict adherence to the KISS principle. I could understand the entire circuit very easily, and everything makes sense.
2) A Luxman LV-111 2 x 50W amplifier, "not working, sold as-is", bought for 33 euros including shipping. It too uses 2 x 6800uF/50V caps in the PS, one of the capacitors had its top off. Replaced the capacitor and a fuse and it's working. Externally it is in mint condition. I admire the work of the production engineers who laid out this amplifier, it is extremely neat and orderly inside. Funny they used a Sanyo STK chip to drive external power transistors.
3) A Yamaha A-760 2 x 80W amplifier "burned, sold as-is", bought for 15 euros delivered. This one uses 4 x 6800uF/63V capacitors. It really had a Rifa RFI capacitor that had exploded, a blown fuse and a small lamp that had burned, which I replaced with a white LED. I somehow managed to find the service manual on the Web and studying this amplifier's relatively complex circuit has been very instructive and enjoyable.
I am fascinated by the "no-nonsense" design decisions of the engineers who designed these three amplifiers (except perhaps the Yamaha that used a daring "X" Power supply configuration). All three date from more or less the same period (early 80's ) and use bipolar power transistors in class AB configuration. They all sound very good (to me, at least), unfortunately I don't have the equipment to measure distortion, SNR, bandwidth and other parameters (I have a Tektronix 2225 oscilloscope and a multimeter, that's all).
I am looking forward to finding a MOSFET-based power amp for not too much and trying to understand it, and the decisions that were made by the people who designed them.
However I confess I don't feel very enthusiastic about the amplifier that was at the origin of this thread. It sold for $77 + $18 shipping and when I think about it that's more or less what I spent for the three amplifiers I bought, with case, transformer, potentiometers, etc.
Merry Xmas to you guys, I enjoy very much reading your posts.
The latest versions have Sanken transistors.
http://cgi.ebay.com/Stereo-Chipamp-...DVWQQrdZ1QQcmdZViewItem?hash=item220065500941
http://cgi.ebay.com/Stereo-Chipamp-...DVWQQrdZ1QQcmdZViewItem?hash=item220065500941
500 WPC
Take a close look at the pics, Its a bridged amp so 35VDC+/- rails could give you around 400watts into 8ohms, and I agree the transistors are probably fakes, but the amp itself is bridged 8 outputs 4 per bridge 4 drivers 2 per bridge 2 input IC's and equal small signal transistors.
All and all put it into a 4ohm load driveing hard it will probably go poof!
Take a close look at the pics, Its a bridged amp so 35VDC+/- rails could give you around 400watts into 8ohms, and I agree the transistors are probably fakes, but the amp itself is bridged 8 outputs 4 per bridge 4 drivers 2 per bridge 2 input IC's and equal small signal transistors.
All and all put it into a 4ohm load driveing hard it will probably go poof!
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