Grateful Dead Music Forum

A place to talk about the music of the Grateful Dead 

 #121251  by Smolder
 Tue Nov 20, 2012 10:43 am
I've heard and experienced the difference in speaker loads on tube amps. And... am a 'proxie' student of Kimock's preachings on tone on another forum, so hooking up a 16 ohm speaker (in this case a 15) to an 8 ohm tap seemed a pretty natural thing to do.

I never thought much about challenging this approach as I got the mc50 up and running with an SMS. Last week, just on a lark, I hooked that 16 ohm speaker to the proper 16 ohm tap and it made a pretty significant difference. It was literally like taking the blanket off... the high end sparkled like it hadn't in a while. I thought it was just the amps limited tonal range.

Wondering if any one else has experienced this on a solid state power amp... of any tech wizards can weigh in. I was pretty surprised.

Also - yesterday I put fresh caps in where the cap can had been wired and this thing just got louder and even clearer with slightly more pronounced upper mids. Glad I made the effort.
 #121276  by GeneralGoldilocks
 Tue Nov 20, 2012 8:39 pm
Seems like there is a lot of conflicting information on mismatching loads on amps. From what I've been told, mismatching the load as you did will create a more compressed and lower output tone in a tube amp scenario (i guess that is why some players like it, it makes an amp break up earlier, as well). That compression may account for the loss of high end sparkle on the mac.

For the system to be most efficient and to put no strain on components, it seems like matching the impedance is in general the best idea out there. Most OT's can handle the load mismatch, and in most cases your gear will survive, but why test Output Transformers and wear out tubes prematurely, especially on a vintage expensive piece of equipment. I have no idea how mcintosh amps handle this. Supposedly Mesa's are safe to do this with, Fender's can handle a mismatch one up and one down (lots of conflicting ideas here), and marshall's can't handle the load mismatch at all. so who knows on a mac?
 #121279  by zambiland
 Tue Nov 20, 2012 9:09 pm
There isn't much a Mac can't handle. I used to run my 2105 into a cab I wired stereo through a metal jack plate. That meant that the negative side of both channels were connected. It got hot as hell and would shut down after 20 minutes or so (of flat out volume). But, once I figured out what the problem was, it was fine. Most amps would have fried.

Whether it will sound good is another question. I think a match is the best option. The multiple taps is one of the beauties of the Mac experience. I'm about to throw a Mercury Magnetics OT in my Showman for that reason.