smurfer77
Super Member
I think the terminology of 'hot' and 'cold' used in the bias measurement of alpha SMs is misleading. The 'Cold' output, is in fact electrically hot too. Seems trivial, but this means you need to take some care when measuring power etc, not to accidentally ground the negative speaker out terminal
The amp outputs should be called '+' and '-' (I like this since '-' in a mathematical sense implies pi (180deg) phase change), or something similar. So moving forwards I'm going to refer to the terminals as "+ out ('hot')" and "- out ('cold')". I added 'out' because I don't want to confuse '+' with a DC supply rail. What do you think?
This has caused confusion to others too. This caused me some confusion the first time I measured the power output on my first Alpha without checking the topology because after I saw 'cold' I figured the negative speaker terminal was tied to ground as usual. A rookie mistake for those working on Alphas (and car amps but this happened to me when I got my first Alpha.
Once you take a proper look at the schematic it is clear that topology is balanced output stage with + and - terminals both driven (out of phase), via 2 amp sections per each channel (one section for 'hot' and one for 'cold' (180 degrees phase shifted with respect to 'hot'). i.e. a type of bridged setup. Again, a simple thing and not that uncommon, but I'm sure I'm not the only one who dived into an Alpha without checking the schematic and topology properly
The amp outputs should be called '+' and '-' (I like this since '-' in a mathematical sense implies pi (180deg) phase change), or something similar. So moving forwards I'm going to refer to the terminals as "+ out ('hot')" and "- out ('cold')". I added 'out' because I don't want to confuse '+' with a DC supply rail. What do you think?
This has caused confusion to others too. This caused me some confusion the first time I measured the power output on my first Alpha without checking the topology because after I saw 'cold' I figured the negative speaker terminal was tied to ground as usual. A rookie mistake for those working on Alphas (and car amps but this happened to me when I got my first Alpha.
Once you take a proper look at the schematic it is clear that topology is balanced output stage with + and - terminals both driven (out of phase), via 2 amp sections per each channel (one section for 'hot' and one for 'cold' (180 degrees phase shifted with respect to 'hot'). i.e. a type of bridged setup. Again, a simple thing and not that uncommon, but I'm sure I'm not the only one who dived into an Alpha without checking the schematic and topology properly