Boogie Mk1 Reissue Impedance?

[Dharmajester]

Just picked up a Boogie Mk1 reissue head.

Manual is rather ambiguous.

I get that in 100watt mode I should run a 8 ohm speaker from the 8 ohm out and that in 60watt mode i need to run two 8 ohm speakers from the two 4 ohm outputs.

However if I run it with 6l6’s at 60watt and tweed setting what impedance do the speaker outs become ?
Any advice would be appreciated

 

[revgsmall]

No, you are not getting it!!!! You can run the amp at 60 or 100 watts with the proper impedance load. If you are just running a single 8 ohm speaker you just plug it into the 8 ohm jack in the back. Mesa says that you can run it into one of the four-ohm jacks and it won't hurt the amp. Personally I don't like the sound at all.

If you are hooking up two separate 8 -ohm speaker cabs, then you can and probably should plug each one in to the 4-ohm speaker jacks. You can also run a two twelve cabinet wired in parallel with 8 ohm speakers (which wired in parallel is a 4-ohm load) and run that into the 4 ohm jack.

All the above combinations can be run at 60 or 100 watts with no damage to the Mark I. I prefer the 100 watt mode to get that great, clear bottom end.

As far as that goofy tweed setting, I gave up on it. You can run 6v6 tubes instead of 6l6 tubes, but only in the "tweed setting" . To me it sounded like a thick blanket over the amp.

 

[Dharmajester]

Yes, that would be logical, however the manual states:

With the toggle switch down ( 60 watt position ), the two middle power tubes are in a “standby mode”, thus reducing the overall power to 60 watts rms. To achieve full efficiency in this position, the speaker should be connected to either of the 4 Ohm speaker jacks.

and also :

Keep in mind that this mismatch ( 60 watt position - 8 Ohm speaker jack ) is a mismatch in the lower than proper match direction. This causes the 6L6 power tubes to wear faster, and produces a much “harder” clip. Again, we encourage you to experiment and find the tonality that suits you best.

Which makes me wonder what exactly is going on ?

 

[DanR]

Basically, at the 100 watt setting, the amp/OT wants to see an 8 ohm load. At the 60 watt setting, as two of the power tubes are disabled, the amp now wants to see a 4 ohm load. Mesa kinda encourages trying out mismatches, but the 100 watt/8 ohm and the 60 watt/4 ohm are the proper matches.

 

[charley]

On a side note, I agree that I definitely like the Boogie MK1 RI in 100w mode better. It is loud, though. Try swapping out the stock 12ax7 tube in v1 for a 12ay7. I did this to mine, and it lowers the overall gain, making the amp more Fender-y to my ears. And a bit sweeter sounding too.

I've had my Boogie MK1 RI for about 10 years, and I am still using the original Mesa 6L6's that came stock. I have only ever used the 8 ohm speaker jack, and have run the amp in both 60/100 w modes with no problem.

 

[RussB]

Yes, that would be logical, however the manual states:

With the toggle switch down ( 60 watt position ), the two middle power tubes are in a “standby mode”, thus reducing the overall power to 60 watts rms. To achieve full efficiency in this position, the speaker should be connected to either of the 4 Ohm speaker jacks.

and also :

Keep in mind that this mismatch ( 60 watt position - 8 Ohm speaker jack ) is a mismatch in the lower than proper match direction. This causes the 6L6 power tubes to wear faster, and produces a much “harder” clip. Again, we encourage you to experiment and find the tonality that suits you best.

Which makes me wonder what exactly is going on ?

That is crystal clear. What are you missing?