I had a bunch of parts sitting around about a dozen years ago and was intrigued by the Herzog by Garnet Amps. I had a Ceriatone 4k3 (probably DC30) OT that they had sent by by accident at some point and told me to keep it.
So I built a pretty stock 5e3 with VVR using that OT (so I had only 4 and 8 Ohm Secondary options using 2 6V6s instead of 4 EL-84s.)
I added dummy load with cement resisters so that I can use just the line out straight into another amp with no speaker plugged in.
I eventually did the Edge mod as well (for normal channel). It does keep the bottom end more under control if wanting to drive it heavy... but I'm still rarely ever using this amp... and neither are my friends.
I want to try something different, and the Tweedle-Dee is currently intriguing me. I don't mind disposing of the dummy load/line out idea if necessary (I'll build a more 5f1 style Herzog down the road). That said, I'm not interesting in gutting this build just to start over as a Tweedle-Dee. I'd like to try out that flavour with reasonable mods.
1) I am hesitant about putting in the GZ34. I have one sitting around, but I wonder if it is counter-productive if I am always running the VVR under halfway all the time already. VVR works great for my and I love that it is also preserving tube life at the same time. So I am wondering how key the GZ34 is to the Tweedle-dee, or is it just to get certain levels of headroom that I am not interested in? This is the one amp where I don't have an extra heatsink on the chassis for the VVR, so I feel like if I use the GZ34, I also need to add better heat dissipation for the MOSFET. I suspect that committing to 32uF filter caps requires the GZ34 because perhaps it's too high of filter cap values for a 5Y3. What thoughts do ya'll have on this?
2) Regarding the filtering... I'm also curious about how those values work. I have a single 33 uF cap in my bin, but I also have 4x 40uF caps and a 22uF and some others:
I'm wondering what's worth trying. I also see that Rob Robinette also suggests not bothering with the 4th cap or splitting to separate cathodes on the input tube. I'd love to know more about how certain choices are made as one works down the B+ line. I often seea much larger first stage and then sometimes smaller values as you progress down the line. I see the Deluxe reverb maintains the same 3x 16uF as the 5e3 but actually adds a 32uF first stage before a choke (while using a GZ34 rectifier). A Hot Rod Deluxe is SS rectified and uses a 47uF, Choke, and then 3 x 22uF caps. Do the resisters values also interact with the caps, or are they more about tweaking the B+ voltage?
I don't mind experimenting a bit. I'm thinking of starting with the preamp and PI (and LNFB) component value mods while continuing to contemplate the power section mods... Basically the stuff on the right side of Rob's layout:
Advice on turning my "Experimenter 5e3" into Tweedle-Dee
Moderators: pompeiisneaks, Colossal
Advice on turning my "Experimenter 5e3" into Tweedle-Dee
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Re: Advice on turning my "Experimenter 5e3" into Tweedle-Dee
Sorry, so the less that I stick to the actual Tweedle-Dee Schematic, the less this should be in the Dumble Discussion section. I did the simpler Robinette changes, and I like them so far.
I didn't split the first tube's cathodes, but switched to a single 470 ohm cathode resister to get the Tweedle load closer.
I didn't have a 3.3M resister for the Local NFB so used a 4.7M instead.
I also didn't have the 110K PI plate and tail load resister, but used 2x 220K in parallel to get the same value. (I'm doing some real dumpster-style hacking here).
For now, I also didn't do the PI balance pot and just did the 100K resister in place of the 33k + 56K + 10K pot... but I am tempted to try the pot for some fun.
I think I am now going to try swapping out the first filter cap only for a 30uF, and see what I think.
I don't know if it would be noticeable, but I could parallel an 8uF on the second cap to get it up to 24uF.... I don't know... there is a certain amount of the loose feeling that I like. I think my favourate of the Marshalls would be the original JTM45 largely because of it's less filtering... So I don't want to clamp things down too much.
I didn't split the first tube's cathodes, but switched to a single 470 ohm cathode resister to get the Tweedle load closer.
I didn't have a 3.3M resister for the Local NFB so used a 4.7M instead.
I also didn't have the 110K PI plate and tail load resister, but used 2x 220K in parallel to get the same value. (I'm doing some real dumpster-style hacking here).
For now, I also didn't do the PI balance pot and just did the 100K resister in place of the 33k + 56K + 10K pot... but I am tempted to try the pot for some fun.
I think I am now going to try swapping out the first filter cap only for a 30uF, and see what I think.
I don't know if it would be noticeable, but I could parallel an 8uF on the second cap to get it up to 24uF.... I don't know... there is a certain amount of the loose feeling that I like. I think my favourate of the Marshalls would be the original JTM45 largely because of it's less filtering... So I don't want to clamp things down too much.
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