I bought a Bedini 25/25
The casework is ok, but the bottomplate destroyed. It has ist transformer replaced by an external transformer. Someone resistierst are replaced, a single from the diffamp also.
I want to restore the amp.
I would like to geht a second hand 220v transformer, Maybach a bottomplate. The handles.
What I need most: Please send me schematics!!!!
Any help is appreciated.
Regs, Dirk
The casework is ok, but the bottomplate destroyed. It has ist transformer replaced by an external transformer. Someone resistierst are replaced, a single from the diffamp also.
I want to restore the amp.
I would like to geht a second hand 220v transformer, Maybach a bottomplate. The handles.
What I need most: Please send me schematics!!!!
Any help is appreciated.
Regs, Dirk
I found this thread:
http://www.diyaudio.com/forums/solid-state/22641-bedini-100-100-need-help-set-bias-2.html
Is post 19 the correct schematic? Voltage (2x 27V) seems a bit high...
http://www.diyaudio.com/forums/solid-state/22641-bedini-100-100-need-help-set-bias-2.html
Is post 19 the correct schematic? Voltage (2x 27V) seems a bit high...
Bedini 25/25 Schematic
The schematics in both posts 18 & 19 are accurate for the Bedini 25/25. Aside from the different types of outputs and the fact that there are more of them, this same schematic is very similar to that for the 45/45 and 100/100. The later BA-801 through 803 series amplifiers had essentially the exact same schematic. The secondary transformer for the original 25/25 has a 42V CT secondary. No doubt some of the other versions of the 25/25 such as the 1 Meg model, used larger transformers, a much larger case and heatsinks and much larger power supply capacitors. However, a 42V CT secondary will still provide sufficient voltage for the output stage to produce about 14 VAC, which yields about 25 Watts into an 8 Ohm Load. The 45/45 uses two of the transformers as found in the 25/25 in series. The power supply under no load for the standard 25/25 is +- 28 V DC. The transformer is rated at 250 Watts. Clearly both the 25/25 and 45/45 had rather small transformers. As they have no protection circuits and have robust output stages, the sizing of the transformers was specified to avoid output stage failures. When the power supplies are much improved the sound quality also improves. I have used a 45/45 with one 500W toroid transformer and 60,000 UF of capacitance per channel and the sound quality was much improved.
The schematics in both posts 18 & 19 are accurate for the Bedini 25/25. Aside from the different types of outputs and the fact that there are more of them, this same schematic is very similar to that for the 45/45 and 100/100. The later BA-801 through 803 series amplifiers had essentially the exact same schematic. The secondary transformer for the original 25/25 has a 42V CT secondary. No doubt some of the other versions of the 25/25 such as the 1 Meg model, used larger transformers, a much larger case and heatsinks and much larger power supply capacitors. However, a 42V CT secondary will still provide sufficient voltage for the output stage to produce about 14 VAC, which yields about 25 Watts into an 8 Ohm Load. The 45/45 uses two of the transformers as found in the 25/25 in series. The power supply under no load for the standard 25/25 is +- 28 V DC. The transformer is rated at 250 Watts. Clearly both the 25/25 and 45/45 had rather small transformers. As they have no protection circuits and have robust output stages, the sizing of the transformers was specified to avoid output stage failures. When the power supplies are much improved the sound quality also improves. I have used a 45/45 with one 500W toroid transformer and 60,000 UF of capacitance per channel and the sound quality was much improved.
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