this circuit has vr10k adj volt 1/2vcc it use vcc55v-100vdc
vdo 100w OTL W????????56-100vdc by fodland - YouTube
vdo 100w OTL W????????56-100vdc by fodland - YouTube
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100W from from a single pair of 2SC5200/A1943? I guess if you had laboratory type super-cooling, you might achieve that number but a practical amplifier will fry when it exceeds 80W RMS. It has no SOA protection either, so it needs to be derated further to ensure it does not fail on peak signal overloads or accidents with input connectors, overdriving etc.
I think 70W would be more realistic but the typical low current power supplies used with such designs are often limited by using a small transformer with poor regulation and this can act like a rubber band, sagging in voltage upon each signal peak and reducing the danger to safe operation. This does work well for safety, just not with high fidelity.
As it stands, the MJE340/350 drivers are lacking current for driving the output stage to power low impedance speakers. There are better, TO220 size types available and not all are expensive. A big mystery though, is what you mean by 2N2504 for Q1,Q3? That is an obsolete thyristor which won't do much as a differential transistor pair. You may have better success with 2N5401, for example.
Q4 is another mystery - How about 2SD669 for the voltage amplifier? It's quite cheap from a number of Chinese producers and also known as H669 etc. It seems to be fairly robust and linear - not too bad as a copy of the original Hitachi semi.
I think 70W would be more realistic but the typical low current power supplies used with such designs are often limited by using a small transformer with poor regulation and this can act like a rubber band, sagging in voltage upon each signal peak and reducing the danger to safe operation. This does work well for safety, just not with high fidelity.
As it stands, the MJE340/350 drivers are lacking current for driving the output stage to power low impedance speakers. There are better, TO220 size types available and not all are expensive. A big mystery though, is what you mean by 2N2504 for Q1,Q3? That is an obsolete thyristor which won't do much as a differential transistor pair. You may have better success with 2N5401, for example.
Q4 is another mystery - How about 2SD669 for the voltage amplifier? It's quite cheap from a number of Chinese producers and also known as H669 etc. It seems to be fairly robust and linear - not too bad as a copy of the original Hitachi semi.
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I would suggest you try the Autona AL125 circuit and use 4 x 2SC5200. I have made it using 4 x MJ15003 TO3 package running at 90v which gave me well over 100 watts into 4 ohms load
Semis like even generic versions of MJ15003 are priced at about $8.00 US ea. in Thailand and the plastic types like 2SC5200, as low as $1 ea. It's a no-brainer as to which type to use there and 2 pairs in parallel does work out to be cheaper and better.
There seems to also be a lot of errors with current Autona schematics shown with 2N3055 transistors and a 90V rail-to rail supply, which must refer to older variations of 2N3055. BD139/140 (shown as 240) drivers wont make the grade either. 'Best to get a reference to a reliable and trusted schematic for that design before enthusiastically buying parts.
There seems to also be a lot of errors with current Autona schematics shown with 2N3055 transistors and a 90V rail-to rail supply, which must refer to older variations of 2N3055. BD139/140 (shown as 240) drivers wont make the grade either. 'Best to get a reference to a reliable and trusted schematic for that design before enthusiastically buying parts.
"wont work" is only the beginning the problems 😉 but the video demonstrated that at least some audio was produced so maybe the schematic is wrong too!
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The schematic probably might work if we put a 62 kOhms series resistor between the zener and the 1st transistor's base 😉.
But 100 watts from one pair of these output devices - no way 🙄.
Best regards!
But 100 watts from one pair of these output devices - no way 🙄.
Best regards!
