Tweedle Dee - few questions ahead of my first project!

[AleS]

Hi all, new to TAG and amp building, please go easy on me if I ask anything a bit silly!

Having gone through a few of the threads about the Tweedle Dee I still have a couple of outstanding questions and I'd love to hear the opinion of a few folks who might have built the amp.

I've been going back and forth a bit in terms of what to build as my first project, the 5E3 came well recommended as it often is but I never fell in love with the tones I heard. That is, until I heard a great demo of it on YouTube. I'd seen the Dumble mods on the Robinette website and they seemed to address my qualms with the 5E3, tightening it up some and smoothening out the breakup to give a cleaner amp that works amazingly well on the edge of clean. That's exactly how I love using my AC30 and I'd be keen to have something that gives me a similar playing experience and interaction but with a different tonal footprint. I guess perhaps, in amp tech terms, what I'm saying is that I might very well jive with the response of a no-NFB amp...!

My main question is around PT. The two I have both go up to 280 on the secondary, without 5v taps. In my head this is still feasible as I'm not too fussed about the GZ34 rectification and perhaps a low value sag resistor might do a good job of softening it up some (not that I'd imagine a GZ34 to sag/struggle much in a Deluxe style amp anyway) while retaining an HT in the lower end of the correct ballpark. I found it interesting to hear in the video posted above how the guy prefers SS rectification and I can see myself enjoy a slightly stiffer/tighter amp anyway since the AC30 does the squishy thing so well. How do you folks recon this might work out? In terms of OT it's all more straight forward as I have two, one is a Marshall 18w OT, the other a 20w, 6.6k primary Deluxe Reverb. Seems obvious I should go for the latter.

I'm making my way through the many resources on here and around the web, but looks like the layout is largely consolidated (ie Alexander Dumble's layout form the original photos). I would be tempted to make the Normal and Bright channels with individual tone knobs for more flexibility (perhaps giving the Normal channel Rob Robinette's lead voicing mod as I don't see myself wanting an overly dark channel), but again, that should all be doable between the pots and the pots' ground bus, making for a pretty minor modification.

Thanks in advance and will update the thread as I make my way through the different steps of the project, slow as it might well be!

[fred.violleau]

Hey AleS,

Great project ! I have now built three different renditions based on the "Tweedle Dee";

-1st one had silicone rectification, Cathode bypass + NFB on a switch and the rob robinette cascading gain mod. No low input, only high input and Lar Mar type 2 MV and FX Loop to insert time based FX before the PI;
Video of these options here :



Loved the amp. Lots of different sounds, from George Benson clean to heavy rock sounds;
I swapped that amp for some unobtainable speakers;

So I needed to build me another one!
-2nd Tweedle Dee was very similar to the first one, but I added relays so I can switch cathode bypass and NFB on the fly, and added an option to switch between fixed and cathode biasing
Fantastic amp, this one I kept and his a reference in my arsenal. I lent it to a friend who does a lot of recording, and he asked to build one for him;

Which brings us to the last rendition :
Single channel (bright channel), tube rectification, with High and low input, Tilt EQ instead of the usual Tone control, cathode + NFB on a switch AND bias vibrato;
That amp sings great as well. I love the vibrato, works really well with the tweed flavor.

My two cents on those experiments:
-This amp does not offer much headroom from the get go, pairing with different speaker will add a bit of headroom or add distortion;
-It is also bass heavy with single coils, even more with humbuckers;
Again speaker pairing is key to balance what you are looking for;
-I realized the normal channel is usually dark, so unless I played jazz stuff, I did not use it; I would mostly play on the bright channel;
-although the original tone knob works, original interaction between the two channels adds complexity to figure out how to dial the sounds properly, lots of interesting videos on YT on this topic. Also the original tone configuration will add mid and highs as well as gain when you turn it up. I prefer to uncouple the two channels interaction. I also replaced the tone control with a tilt EQ and it adds interesting options sonically without compromising the original sound;
-silicon rectification seems to be a bit stiffer, but it was not a game changer;
-cathode bias vs fixed bias was not a game changer either, very subtle on the tone and feel of the amp;
-Voltages mattered to me, I usually gravitate towards 400V on the B+, higher felt stiffer and I liked it less;
-High and low inputs are interesting if you want to hit the front harder when switching from humbuckers to single coils ;
-I usually gravitate around the edge of breakup, but enjoys going harder when needed (cascading is a great option);
-cathode bypass and NFB are great to add versatility and different sounds from the original design) so you will be able to dial in different flavors of the edge of break up;
-Master Volume : the most transparent one to me was the LAR AMR type 2, tried other configuration which I thought changed too much the caracter of the amp. And when max the MV is transparent and the amp behaves just like a stock tweedle dee;

SPEAKERS

ET95 by WGS are offering a big and full sound in a 2x12 configuration and allows to push the amp hard (cascading and big volumes)
Celestion greenback gets you into rock territories (ok sounding but not my favorite)
Celestion alnico blue is the most balanced option with a single 12 (not to bass heavy) and a chimy edge of break up

Lots of rambling here... hope that may help you figure out what seems to be right for you;
Good luck with your project!
No matter which option you pick, this will be a great amp as it is a simple, yet great design;

Cheers;

Fred.

[AleS]

Hey AleS,

Great project ! I have now built three different renditions based on the "Tweedle Dee"

...

Hey Fred thank you so much for the detailed post which offers a lot of ideas and food for thoughts! Also apologies for the slow reaction - I'd completely missed the post as it's been a busy past couple of weeks.

First of all, it confirms the sounds this should give me are definitely something I'm interested in, which is great. It also reassures me that going SS rectification and with potentially lower voltages due to the PT maxing out at 280 should not be an issue as I wouldn't want the amp to be overly stiff, which high voltages contribute too in your pretty extensive experience. I'm thinking of leaving the door open for a potential low value sag resistor should I find the amp too stiff but again, some stiffness is good and a welcome alternative to my squishy AC30.

Like you, I don't see myself having too much use for the Normal channel and had thought about putting a bright cap in that too but swapping the coupling cap back to the 5E3 value of 0.1 thinking this might yield a bit of wooly, more classic tweed tone. Alternatively, I'd thought about giving each channel an individual tone control, with the Normal channel retaining a bright cap but perhaps with a Big Muff style tone control to have a mid-forward Ch1 and a scooped, more Fendery (with the aid the Duncan TSC) Ch2. Is having individual tone controls what you mean by "uncouple the two channels interaction"? And is the tilt eq effectively what I called a Big Muff tone control, blending between a high- and a low-pass filters?

As you say, it strikes me a simple, pure amp which should give quite a few tonal options, especially with the NFB switch. On that topic, do you find the middle position to be of much use?

Thanks a lot once again! And of course, any word of wisdom from any other builder would be more than welcome

Hopefully I'll be able to to update the thread soon with the first few steps of the build. It'll be a slow process, but that's probably a good thing since having shorter moments to work on it should mean being able to focus on individual parts of the process without too much pressure, as one should do for a first foray in something like an amp build

[fred.violleau]

Hey Ales,

Sorry for the late reply, it's been a busy september for me as well;

To answer your questions :
- Is having individual tone controls what you mean by "uncouple the two channels interaction"?
No, if you take a look at the schematic (or the layout), you will see that the volume pots are both connected on pin 3 and then feed the plate of the next amplification stage; The connection on PIN 3 allows interaction between the volumes controls and tone control even if you are only playing on one channel.
There is a great video on youtube, but I can't seem to find it, but found this website that explains the interactions and the variety of tones the interactions produce :
https://kr-sound.com/tweed-deluxe-channel-interaction/

- And is the tilt eq effectively what I called a Big Muff tone control, blending between a high- and a low-pass filters?
The big muff shapes the frequencies in a similar way to the tilt, but the actual tilt circuit is active and boosts as well as cuts freq, whereas the Bif Muf circuit is a passive filter (only loosing frequencies).

- Do I like the middle options for the NFB switch
Absolutely, the variety makes it usefull in different context. I even put these options on a footswitch in my second build so I could change settings on the fly while playing;

Best of luck with your build and take your time, the fun is in the journey !

Fred.

[AleS]

Hey Ales,

Sorry for the late reply, it's been a busy september for me as well;

Likewise, apologise for clocking this late and thanks again for the respons!

To answer your questions :
- Is having individual tone controls what you mean by "uncouple the two channels interaction"?
No, if you take a look at the schematic (or the layout), you will see that the volume pots are both connected on pin 3 and then feed the plate of the next amplification stage; The connection on PIN 3 allows interaction between the volumes controls and tone control even if you are only playing on one channel.
There is a great video on youtube, but I can't seem to find it, but found this website that explains the interactions and the variety of tones the interactions produce :
https://kr-sound.com/tweed-deluxe-channel-interaction/

I'd never taken enough care to see the volume controls are indeed set up very differently, in that you'd normally see lug 2 as your output!

- And is the tilt eq effectively what I called a Big Muff tone control, blending between a high- and a low-pass filters?
The big muff shapes the frequencies in a similar way to the tilt, but the actual tilt circuit is active and boosts as well as cuts freq, whereas the Bif Muf circuit is a passive filter (only loosing frequencies).

Will definitely look into this!

- Do I like the middle options for the NFB switch
Absolutely, the variety makes it usefull in different context. I even put these options on a footswitch in my second build so I could change settings on the fly while playing;

Copy that!

Best of luck with your build and take your time, the fun is in the journey !

Fred.

Thank you so much one again for the information and food for thoughts! Definitely keen to take my time with this and enjoy the process, while taking the opportunity to ponder each step - hopefully I'll have learned something new by the end of it!