In my case I have a McIntosh MC452 (solid state amp with autoformers) driving a pair of Focal Sopra No2 speakers. Focal lists the "nominal" impedance at 8 ohms, but the "minimum" impedance at 3.1 ohms, so my dealer recommended that I connect them to the 4 ohm taps on the amplifier.
MAC Autoformers?
Someone is selling a MAC MA6500 Integrated claiming its superiority over the Ma6600 due to the fact that "it does not have the degrading autoformer design found in the MA6600". That is the first time I've heard a claim that the autoformer was a hindrance to better performance; I thought quite the opposite. What do you MAC Maves think?
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https://www.stereophile.com/content/mcintosh-mc501-monoblock-power-amplifier-measurements-0 I have to admit that I was quite pleasantly surprised to see the amp double down from it's 8 Ohm tap down to 4 Ohms, but from there down to 2 Ohms, it was even worse than I expected. |
was quite pleasantly surprised to see the amp double down from it’s 8 Ohm tap down to 4 Ohms If you don’t change the tap, it doesn’t double at all when the load impedance halves from 8 to 4ohms And you can’t change the trany tap from 8 to 4 half way through a musical note, when it decides to dip from 8ohm to 4ohms then back up again. Autoformers good interim fix for amp/speakers if the amp can’t drive the speaker without it, till you get the right amp Cheers George |
It doesn't sound like transformers are that well understood by some. Their big failing is that they are massive inductive loads on the output devices. They don't insulate the amp from the load because things happening on the secondary definitely do show evidence on the primary. That's even more the case with autoformers because the primary and secondary are electrically connected. I guess they serve a purpose, but not in amps I like or build. I don't think it makes sense to put a few hundred feet of wire and a couple pounds of iron between gain devices and the load if you don't have to. |
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