Hi there.
Can anyone out there suggest a bi-polar or digital alternative for rebuilding some old Class B (1980's)mosfet amps. I have HUGE power supplies (68-0-68 Vac) and smoothing (20 000uf per rail), heatsinks and cases.
I would need to get a component list and a PCB design.
Would you be kind enough to help with this project?
Regards,
John
Can anyone out there suggest a bi-polar or digital alternative for rebuilding some old Class B (1980's)mosfet amps. I have HUGE power supplies (68-0-68 Vac) and smoothing (20 000uf per rail), heatsinks and cases.
I would need to get a component list and a PCB design.
Would you be kind enough to help with this project?
Regards,
John
Just doing a bit of Googling for you.
I have found this design....http://3.bp.blogspot.com/-zNZi3Xw8j...AAAdg/gimcj9Y_n8g/s1600/Actrk600schematic.jpg
I have found this design....http://3.bp.blogspot.com/-zNZi3Xw8j...AAAdg/gimcj9Y_n8g/s1600/Actrk600schematic.jpg
What's your goal for the rebuild?
The honey badger is a nice design, very low distortion and easy to get stable. I've built variants of it, not on its official PCBs but by modifying vintage PCBs in vintage gear. It's only a minor variation on the common Lin topology used by most class AB solid state amps ever made so PCB reuse is possible.
With boosted supplies for the amplifier front-end, that you likely already have, the honey badger could be adapted to use MOSFETs.
The honey badger is a nice design, very low distortion and easy to get stable. I've built variants of it, not on its official PCBs but by modifying vintage PCBs in vintage gear. It's only a minor variation on the common Lin topology used by most class AB solid state amps ever made so PCB reuse is possible.
With boosted supplies for the amplifier front-end, that you likely already have, the honey badger could be adapted to use MOSFETs.
First of all IMHO there's nothing wrong with MOSFETs in the right circuit.
You might look at the circuits Nelson Pass donated to the public for private use.
Be more specific...what 'ya got? Some old Soundcraftsmen stuff?
You might look at the circuits Nelson Pass donated to the public for private use.
Be more specific...what 'ya got? Some old Soundcraftsmen stuff?
Have a look at the APEX designs posted in this Forum in the solid state section.
They are very reasonable amps, there's a couple versions which are quite flexible, one of them will be happy with your cabinet, heatsinks and power supply.
They have been built by many so reading the threads will provide a lot of practical building info and ideas.
Part of your problem will be more "mechanical" than "electronic", trying to fit new stuff within the physically available space matching what you already have, so going for a relatively simple design will help you.
They are very reasonable amps, there's a couple versions which are quite flexible, one of them will be happy with your cabinet, heatsinks and power supply.
They have been built by many so reading the threads will provide a lot of practical building info and ideas.
Part of your problem will be more "mechanical" than "electronic", trying to fit new stuff within the physically available space matching what you already have, so going for a relatively simple design will help you.
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Yeah, you'll really need to give better information.
A few jpegs posted would reduce the uncertainty.
Assuming that the Mosfets are good, and there are enough of them, then it is a good idea to re-use them. Otherwise, what do you have besides a power supply and maybe some heatsinks and chassis?
What's wrong with the old amps??
Might be worth repairing, possibly.
I'd stick with a Mosfet design, since you have the Mosfets.
How about some more information?
Also what do you want to DO with the amps when they are working?
A few jpegs posted would reduce the uncertainty.
Assuming that the Mosfets are good, and there are enough of them, then it is a good idea to re-use them. Otherwise, what do you have besides a power supply and maybe some heatsinks and chassis?
What's wrong with the old amps??
Might be worth repairing, possibly.
I'd stick with a Mosfet design, since you have the Mosfets.
How about some more information?
Also what do you want to DO with the amps when they are working?
mosfet amp rebuilds
Hi there, and thanks to those who have replied and will still do so!
The reason for these rebuilds are that these amplifiers had a pretty poor reputation for reliability even when new😡. With the power-supplies, smoothing, heat-sinks and cases available, one can get far more power and reliability than these ever were. The other reason is that mos-fets, when they are obtainable, are incredibly expensive in this country🙁. Bi-polar transistors, on the other hand, are more easily and economically sourced. Please refer the photos(sorry, not very good quality😱) attached to see what I'm talking about.
Hi there, and thanks to those who have replied and will still do so!
The reason for these rebuilds are that these amplifiers had a pretty poor reputation for reliability even when new😡. With the power-supplies, smoothing, heat-sinks and cases available, one can get far more power and reliability than these ever were. The other reason is that mos-fets, when they are obtainable, are incredibly expensive in this country🙁. Bi-polar transistors, on the other hand, are more easily and economically sourced. Please refer the photos(sorry, not very good quality😱) attached to see what I'm talking about.
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