I figured I’d easily find an old Internet thread with a list of unregulated amps but no luck. I started to build my own but soon discovered products like the Supernait are unregulated so perhaps the list of regulated amps is actually the shorter one? Can anyone help compile the shorter list. Tx
Are you restricting yourself to Naim, or does this relate to every amp ever?
Just Naim 
250, 135, 145, 300, 500, Statement. I’m not sure about the NAB300 from 1979.
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Great, thanks HH. Quite a short list in the end. Never heard of the 145 before.
Basically, anything related to the 250, is a regulated design. Guess we should include its predecessor, the original 200…? Not sure… 135 & 300 definitely - as direct 250 derivatives. I believe the 500 is effectively a bridged 250…?
Am sure @Richard.Dane can confirm, for us.
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The NAP-V145 was a single channel version of the NAP250.2, intended for AV use.
Yes, the original NAP200 was the first regulated amp, and this was then developed into the NAP250.
I’d forgotten the original 200. Do you know how the NAB 300 fitted in? And NAB rather than NAP, do I recall it was a BBC specific amp?
The NAB300 was a professional version of the NAP250 for studio use. It used similar amp and reg boards but balanced input and frame transformer. According to Naim it didn’t sound as good as a regular NAP250.
Thanks Richard. Was it therefore B for Broadcast?
Possibly, or B for balanced.
I bet that was jolly good for its day
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That is the first time I have seen a picture of the NAB300, other than in the Naim catalogue.
Thank you, Harry…
Wow!!! 
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Here are a couple more, one with lower capacity reservoir caps.
Fun fact - the rear fan is rated at 240V & runs at full tilt all the time.
Regards
Neil.
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There’s definitely something very cool about them, the power amp PCBs are hidden away within the heatsink.
Regards
Neil.
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