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PostPosted: Sat Jul 12, 2014 5:14 pm 
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I just finished building the Royal, seems to work fine. I built it using the chassis and cab of an old solid state Peavey Pacer, so I've got some room left over in there, and a couple of weeks vacation time left. So I'm thinking, perhaps I could add a tremolo circuit?

Could a bias tremolo work, like on the Tremolux? Would the dual modes (SE/PP) make it too difficult?


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PostPosted: Sat Jul 12, 2014 9:36 pm 
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The old tweed tremolo schemes won't work on this amp because they either used bias vary trem on a fixed bias scheme, or used cathode vary trem with a paraphase phase inverter. The TR is cathode biased with a split load phase inverter.

I see 4 options:

Build an outboard trem like the EA Tremolo. I kind of think it sounds better than actual amp trem wi the way it wiggles the gain.

Convert the TR to fixed bias ala a brown face Princeton bias and trem circuit. You need to add a tube, and it's unknow if the power transformer can handle another tube.

Use the vibro champ tremolo circuit. Agains, needs another tube.

Try out the old Danelectro grid bias vary tremolo circuit, like on the Silvertone 1333. Again, another tube.

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PostPosted: Mon May 10, 2021 5:51 am 
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I just might do this mod one of these days... @byoc what are the specs of the BYOC-TRPT1 power transformer and can it handle another 12AX7?


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PostPosted: Mon May 10, 2021 10:52 am 
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The output needs to be a fixed bias, not cathode bias for a bias trem like the tremolux. As Morgan pointed out, you'd need to make some modifications to do this. Not super easy mods, but doable. The problem I foresee is with SE mode. I've never seen a fixed bias SE amplifier before. With the cathode bias, the PP mode cathode resistance is literally half the resistance of the SE mode, so it was just a simple matter of using the rotary switch to put a resistor in and out of parallel. The output transformer doesn't care how the tube is biased, so that won't be a problem if you switch to fixed bias, but as far as switching between the two modes and making sure each is biased correctly.....that might be difficult. I don't know. It might not. But you'd be blazing your own trail, so I don't know how much help I can provide.

Yes, the PT can handle one more 12AX7, but not much else. The TRPT1 is just a standard 5E3 PT. We just had the primaries internally wired so that it had designated 120v and 240v taps rather than having dual primaries that needed to be wired in parallel or series...to make it easier to build.

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PostPosted: Mon May 10, 2021 7:05 pm 
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Thanks, Keith. I'll probably have a go at the Vibro-Champ tremolo circuit so I don't have to convert it to fixed-bias.


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PostPosted: Sun Jun 13, 2021 9:44 pm 
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I finally did add the Vibro-Champ tremolo to the Tweed Royal. Sounds great, except for the terrible ticking. Any good hints about getting rid of that? I might try shielded cable in the signal path to see if it stops picking up the ticks. Moving the oscillator caps around and out of the chassis didn't do anything.


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PostPosted: Mon Jun 14, 2021 10:06 am 
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PostPosted: Mon Jun 14, 2021 10:51 am 
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Meddler wrote:
I finally did add the Vibro-Champ tremolo to the Tweed Royal. Sounds great, except for the terrible ticking. Any good hints about getting rid of that? I might try shielded cable in the signal path to see if it stops picking up the ticks. Moving the oscillator caps around and out of the chassis didn't do anything.



Where do you have the signal from the intensity pot connecting to the tweed royal? Most trem circuits will have some sort of low pass filtering on the LFO signal to reduce ticking. I don't see any sort of LP filtering on the vibro champ. You might need to add that.

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