Maybe I have not been clear enough: both the Elektor amps (with Quad 303 style triples) with single 2N3055 's and Wireless World ( B.J.Cody?) 2955/3055's provided some 40 Watt RMS in 8 Ohms, so with triple output devices some 5 amps output should not be a problem with 3-4 Ohms load?
Reichelt advertises the 2N3055 for 100V: https://www.reichelt.de/bipolartransistor-npn-100v-15a-115w-to-3-2n-3055-p1987.html
Hey @Boden
It is True that 2N3055 do have a 115W PD but the package that is used in the present amp is TO-3P / TO-247 which has a lower PD of 90W only as per the SOA chart for the transistor maximum you could do is 3Amps at +/- 30volts
Yes, 2 ohms with 3 pair of TIP35 OR 2N3055 - on +/-30 volts. Neither has an SOA problem at that voltage. If the S/B breakpoint is greater than or equal to one rail, you are generally safe. Any current that could exist at higher vce will be short-lived. Less than a quarter of a cycle at a time. Push your supply rails higher and the 3055’s actually fare better with the higher breakpoint. But their gain falls like a stone above 2 amps, where the TIPs will hold up decently to about 12. Trades one set of problems for another. At the higher voltages you need better transistors overall- higher S/B breakpoint AND better gain linearity. Then you just buy the more modern ON or Toshiba.
Ian, do you happen to have spice models for these KEC transistors (or their equivalent)?
I bought whole batch of them, and I'm going to try them.
Hi, unfortunately no. The last Sanyo datasheet for the OEM product was apparently before Spice models were offered for general distribution and they don't make reference to any, as far as I can tell. I doubt that 2nd source manufacturers like KEC, Mospec, ST Micro, Wingshing and others, would have offered the support of spice models for their versions anyway.
Here is a simulation of triple amp (50V rails) with KEC transistors KTB817 and KTD1047.
They are still being produced (in Korea), and can be ordered from Tayda Electronics (75 cents each !). It's a steal!
They are equivalents of old Sanyo 2SB688, 2SD718 that were used in late 70s and 80s Japanese amps by Marantz, Pioneer, Toshiba and many others.
Very good sounding amps.
I was not able to find exact models for them (at least not for 2SD718), so this sim is very crude approximation.
All harmonics are under -120dB (inaudible); Thd is minimal, and it seems to be stable.
This will be next amp to build (after I'm done with new Circlophone), and I can re-use PCBs I made for the smaller triple amp..
They are still being produced (in Korea), and can be ordered from Tayda Electronics (75 cents each !). It's a steal!
They are equivalents of old Sanyo 2SB688, 2SD718 that were used in late 70s and 80s Japanese amps by Marantz, Pioneer, Toshiba and many others.
Very good sounding amps.
I was not able to find exact models for them (at least not for 2SD718), so this sim is very crude approximation.
All harmonics are under -120dB (inaudible); Thd is minimal, and it seems to be stable.
This will be next amp to build (after I'm done with new Circlophone), and I can re-use PCBs I made for the smaller triple amp..
