Multi-Watt speaker / ohms setup in 50w mode

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Mark III
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Multi-Watt speaker / ohms setup in 50w mode

Post by GJgo » Tue Jan 01, 2019 8:54 am

Hey guys, I couldn't find an answer to this question in the literature so I asked Mesa, figured I would share.

In my old Mark hundred watters, its known that if I flip the switch to 60w mode to maintain a proper load match I would want to move the 8 ohm speaker load to the 4 ohm jack. I could not find anything about this in the Multi-Watt literature so I asked if this was also the case here or if the amp somehow handles it internally. I was told that the amp has no way to handle it internally so I can move the jack if I want to. Reading between the lines, I think that they're not worried about it since the OTs on Boogies are so robust, but I figure if I can have a correct match I'd like to since an incorrect match will change the response & feel.

Before I asked, one night I was rehearsing (loud) with my band with the amp in 50W mode in the 8 ohm jack and I noticed that I ran out of headroom- I had to dime the solo boost to get it to be a little louder for leads. I'll have to try it again now with the proper load..

Mark II
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Re: Multi-Watt speaker / ohms setup in 50w mode

Post by tbonesullivan » Tue Jan 22, 2019 10:05 am

I'd say email mesa boogie customer service. They are usually very good about getting back to customer inquiries.
Guitars: Hamers, Heritages, G&L Legacies, EBMM Steve Morse, Carvin Bolt, Fender Tele
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Re: Multi-Watt speaker / ohms setup in 50w mode

Post by bandit2013 » Sun Mar 24, 2019 1:20 pm

When you run at 50W, the only change is the drop of two tubes. Nothing else changes to keep the headroom consistent to the 100W power setting. Yes this will tend to saturate the two tubes more so than with 4 tubes. Change in speaker connection (8 ohms into the 4 ohm jack) will not improve the headroom issue. There is a brief note in the manual on page 12 (on-line version) that states it is not overly sensitive to mismatches but that is about it.

Also what color coded power tubes are in your amp? You may gain a small amount of additional headroom with Red coded tubes but probably not as much as you need based on your description. Sorry of not helping your situation.

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