Hello there.
I have a trashed Rotel RB-2000. Usable are housing, power supply, power meters and heat sinks.
Does anybody have idea for good AB class DIY amp where I can use power supply from this amp (70-75 Volts)?
I do not remember such schematic.
Best regards
I have a trashed Rotel RB-2000. Usable are housing, power supply, power meters and heat sinks.
Does anybody have idea for good AB class DIY amp where I can use power supply from this amp (70-75 Volts)?
I do not remember such schematic.
Best regards
Look for transistor amp modules, generic item here.
About $20 with heat sink, just mount and connect it.
About $20 with heat sink, just mount and connect it.
Can you please look and suggest a clickable link?
Suggesting somebody to go google it as an answer is a waste of time and bandwidth.
Suggesting somebody to go google it as an answer is a waste of time and bandwidth.
Look at this, gives you a pretty good idea about what to do:
I do not have any ties to the seller, or publisher of the article.
I do not have any ties to the seller, or publisher of the article.
is that 70V as in 35+35V? There are heaps of kits for 50-150W amplifiers that run at those voltages.
The diyaudio-flavoured discrete amps are honey badger and wolverine as posted above. Si Chip and other mags have published a few decent amps in that range too. You could also do a big chip-amp e.g. parallel and bridged LM3886 or TDA7293 to get 2x150W (subject to PSU stiffness) into 8R under 0.01% THD.
Or just stack a whole bunch of separate chip-amps in there for a 6x70W/8R active system or home-theatre system or whatever. That will be PSU-limited i.e. you can't drive all the channels at full power concurrently, but that's fine for most purposes because high-frequency (in active crossovers) or home-theatre rear channels need comparatively little power.
What's your use case?
The diyaudio-flavoured discrete amps are honey badger and wolverine as posted above. Si Chip and other mags have published a few decent amps in that range too. You could also do a big chip-amp e.g. parallel and bridged LM3886 or TDA7293 to get 2x150W (subject to PSU stiffness) into 8R under 0.01% THD.
Or just stack a whole bunch of separate chip-amps in there for a 6x70W/8R active system or home-theatre system or whatever. That will be PSU-limited i.e. you can't drive all the channels at full power concurrently, but that's fine for most purposes because high-frequency (in active crossovers) or home-theatre rear channels need comparatively little power.
What's your use case?
Last edited:
Link in my post above was broken.
Search for: 2sc5200-2sa1943-amplifier-board-200-watts-
Image below from Indian site, no ties to seller.
I checked, it is a mono version.
Similar stereo versions are a generic item here.
Free advice: buy with heat sink, less hassle.
Search for: 2sc5200-2sa1943-amplifier-board-200-watts-
Image below from Indian site, no ties to seller.
I checked, it is a mono version.
Similar stereo versions are a generic item here.
Free advice: buy with heat sink, less hassle.
Attachments
Last edited:
Class D modules may be available, not my area of expertise.
Basically, the supply voltage needed should match your power supply.
Basically, the supply voltage needed should match your power supply.
BIG difference between 70 volts total and +/-70 volts. The former will be happy with one pair of output transistors and a simple circuit. Protection circuits could almost be considered optional. The latter requires something like Naresh posted - 5 pairs of C5200’s and a big (or forced air) heat sink. And DC protection, SOA limiting, fuses and the like are not optional.
The amp is 120W/ch into 8 ohms, from 1978.
Described as heavy duty, response from 5 Hz to 100 kHz, 0.01% THD.
18 kilos, or 40 lb. approx.
Picture shows enormous heat sinks.
Not for the faint hearted, nor a small room. It is more suited for a cinema, or auditorium. Or a really large room.
Described as heavy duty, response from 5 Hz to 100 kHz, 0.01% THD.
18 kilos, or 40 lb. approx.
Picture shows enormous heat sinks.
Not for the faint hearted, nor a small room. It is more suited for a cinema, or auditorium. Or a really large room.
That is NOT a "70V rail" amplifier but a +/-70V one; as mentioned above a very different thing.
I can not access Elektrotanya but here´s the link:
https://elektrotanya.com/rotel_rb-2000_sm.pdf/download.html
please somebody download it and upload it here.
I can not access Elektrotanya but here´s the link:
https://elektrotanya.com/rotel_rb-2000_sm.pdf/download.html
please somebody download it and upload it here.
+/- 70V
And I am looking for something on high end side.
Not finished modules or D class.
I built before Pass/Thagard A75 mono blocks and do not need something in A class.
Something like M. Leach but for +/-70 V 🙂
Tnx for suggestions.
And I am looking for something on high end side.
Not finished modules or D class.
I built before Pass/Thagard A75 mono blocks and do not need something in A class.
Something like M. Leach but for +/-70 V 🙂
Tnx for suggestions.
Are you sure about the 70+70V? Is that by any chance the unloaded/idle voltage, and the true operating point of the PSU under full load might be more like 60+60V? The Rotel claims 120W/8R which is 31VAC or about 44V peak. So yeah it's definitely not 37+37... but it's a fair bit more voltage than you need/want for a 120W/8R amp.
If it really were good for 70+70V, you could probably swing 60V peaks, which is more like 225W/8R.
I have an old amp that I built from a kit (Electronics Australia 1995, 200-300W "Playmaster") as a kid, which runs at that kind of voltage using 6 of TO3 MJ15003/15004 in each output stage. It's grunty of course but is not so very hi-fi by today's standards; good enough for woofers/subs.
If it really were good for 70+70V, you could probably swing 60V peaks, which is more like 225W/8R.
I have an old amp that I built from a kit (Electronics Australia 1995, 200-300W "Playmaster") as a kid, which runs at that kind of voltage using 6 of TO3 MJ15003/15004 in each output stage. It's grunty of course but is not so very hi-fi by today's standards; good enough for woofers/subs.
What about my earlier suggestions (Honey Badger, Wolverine)? If you don't like those, it might be useful to let us know the reason so we can think about better suggestions.
I thought the same. Maybe the specified 8 Ohm power is determined by the current limits or heat. That said, I have not seen any hints about the rail voltages in the service manual.
Our NS Modular series amps work well on +/- 75V supplies. https://www.diyaudio.com/community/...-ideas-from-1970s-ips-ops.277087/post-4389599
Ostripper's Slewmaster series are another option. https://www.diyaudio.com/community/threads/slewmaster-cfa-vs-vfa-rumble.248105/post-3753356
Ostripper's Slewmaster series are another option. https://www.diyaudio.com/community/threads/slewmaster-cfa-vs-vfa-rumble.248105/post-3753356
Just found the quite obscure transistor datasheet, and not theoriginal NEC one but a scond source supplier or overstock reseller::
https://datasheet.octopart.com/2SC2337-Inchange-Semiconductor-datasheet-15978679.pdf
130Vcer so rails are +/-55V , tops.
Which is more consistent with 120W@8 ohm rating.
Not sure where +/-70V came from.
Maaaybeee amp is actually Japan 100V mains and was plugged into 120V?
Or simply those 70V were estimated or just main capacitors rating?
Power toroid looks beefy, wouldn´t expect it to drop much, and that´s an understatement.
Hope this clears the field and certainly some of the above suggestions look more than competent, only problem remains to fit new amp and transistors into available space, should be quite doable.
EDIT: just found main capacitors C003/004: 15000uF@63V so definitely rails not higher than +/.55V
https://datasheet.octopart.com/2SC2337-Inchange-Semiconductor-datasheet-15978679.pdf
130Vcer so rails are +/-55V , tops.
Which is more consistent with 120W@8 ohm rating.
Not sure where +/-70V came from.
Maaaybeee amp is actually Japan 100V mains and was plugged into 120V?
Or simply those 70V were estimated or just main capacitors rating?
Power toroid looks beefy, wouldn´t expect it to drop much, and that´s an understatement.
Hope this clears the field and certainly some of the above suggestions look more than competent, only problem remains to fit new amp and transistors into available space, should be quite doable.
EDIT: just found main capacitors C003/004: 15000uF@63V so definitely rails not higher than +/.55V
Last edited:
Did you have a look a the wolverine.
There is a GB for boards at the moment if your interested.
There is a GB for boards at the moment if your interested.
Looks good but can you please post the schematic? 🙂
Only doubt could be whether it fits the available space or not., can you provide board dimensions?
Also guess PSU would be built on a separate board.