Last week, a Sears Silvertone 1482, this week, a Mesa Boogie Mark II. When it was new the 1482 came with an 8ohm speaker, and the output transformer was wired for 4 ohms. The Mark II has a sticker that says, "100/60 (watt) models use 4ohm jack for 8ohm speaker." This amp has (1) 8ohm jack and (2) 4ohm jacks (in parallel). Is there a reason why we would disregard the standard way of connecting an output transformer? Thanks
Looking at the schematic for the Mesa Mk II, there seems to be one jack on an 8 ohm transformer tap (for a single 8 ohm speaker) and two jacks in parallel on a 4 ohm tap (for two 8 ohm speakers used simultaneously).
I should have added that a single 4 ohm speaker can of course be plugged into one of the parallel jacks on the 4 ohm tap.
Agreed. As to what Malcom said, that is exactly what I instruct tube amp users to do with their outputs. BTW, thank you Malcom for taking a look at the schematic, I love that you care! But these two amps came from the factory this way - in both cases, an 8ohm speaker was knowingly placed or instructed to be placed on a 4ohm tap.
They like the sound and response better that way. It surely will not harm the amp in any way. We were a Mesa dealer in the 80s, and that was a common note on the amps. It shoves the tubes down the curves a little ways, that's all.
Wow, thanks everybody. I read the User Manual for the Mark II. In paraphrasing, they say that achieving max output power and clarity are the only technical reasons to properly match the OT to the speaker load. Other combinations will affect tone subjectively or allow one of two speakers to be louder than the other. Also, for guys running a single 8ohm speaker with a full 100 watts and the lead overdrive engaged, you are less likely to blow up the speaker on the 4ohm tap.
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