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Post by michaelo101 on Dec 6, 2020 9:10:34 GMT -7
I'm vaguely familiar with the practice of pulling the two outside EL34s on an amp to reduce the power by roughly 50%. Is this O.K. on the Mazerati, to pull the two outside (or two inside) EL-84s to cut the power in half? What change should I make in choosing speaker outs regarding speaker cab impedence? (I have an assortment of 16 and 8 ohm cabinets from which to choose.)
Thanks very much in advance, Michael
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Post by headshrinker (Marc) on Dec 6, 2020 13:03:31 GMT -7
The Mazerati is cathode biased. I'm 99% positive you can't pull two tubes on a cathode biased amp to reduce the power. It screws up the biasing. You can do it on a fixed biased amp like a Twin or four input Marshall.
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Post by Chilly Gibbons (Todd T.) on Dec 6, 2020 13:51:04 GMT -7
Use a quality attenuator, with ALL output tubes in place. Don’t try that on a cathode biased amp. Also, pulling inside or outside tubes assumes that builder wired the push-pull that way. It can just as easily be that the A in A/B is the inside tubes and the B is the outside, or reverse of that. Also changes the load on the output transformer in a bad way.
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Post by "Z" Steve on Dec 6, 2020 13:55:23 GMT -7
Welcome to the forum! You can get great quality advice (along with opinions!) here on the Z Forum. If you do not get an immediate reply, which is rare, you can most likely get your answer from using the search function.
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Post by michaelo101 on Dec 6, 2020 14:06:30 GMT -7
Thanks very much for the fast and clear replies. It's a no-go then. I had done the tube pulling thing with an old Marshall years ago and it helped, but Dr. Zs are definitely their own thing in terms of tone (awesome, I have an early Ghia, too), so I figured the power section was different than a Marshall.
I do have an old Altair attenuator that has been babied and works well. I also should try out a clean boost.
Thanks again. This is a friendly and educational place.
Michael
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