Another Tweddle Dee !

[Guy77]

Hi Fred and Marcus, your videos sound great! I really like the bluesy tones these amps can get. They have a great growl to them as well and so much easier to build than many of the other amps here. As da Vinci said, "Simplicity is the Ultimate Sophistication".

Cheers!

Guy

[norburybrook]

Sounds great Marcus! Are your coupling caps per the original Tweedle or have you adjusted them? The 680k is (should be) before the 1M grid resistor so using 640k will put a little more signal into the second stage, not much difference, really.

The Schematic at the beginning of this thread is not correct in the speaker connections, maybe that could be fixed up. NFB should come from the hot side, and the speaker jacks are just the standard Fender arrangement where the extension speaker is paralleled with the main.

Martin,

I have a 470k grid stopper in that position, the 680k is wired on the switch which is supposed to cut the gain going from one stage to another.

here's the layout I worked from.

5e3p_Cascade_Mod_Schematic.png

5e3p_Cascade_Mod_Switch.png

5e3p_Cascade_Switch.png

M

[norburybrook]

Hi Fred and Marcus, your videos sound great! I really like the bluesy tones these amps can get. They have a great growl to them as well and so much easier to build than many of the other amps here. As da Vinci said, "Simplicity is the Ultimate Sophistication".

Cheers!

Guy

Yes, with a few tweaks they're incredibly versatile too. Picking the right speaker and dialling in the bass you want is the tricky thing with these amps as they have a lot of bottom end. I think a pair of 10s in a cab might be perfect. I'm thinking of throwing together a 2x10 cab just to see....my neighbour has a large sheet of plywood in his front garden that's going to the waste....I saw it and thought...'that would make a cab'


M xx

[martin manning]

Marcus, right so in that schematic above it shows the wiper of the gain/volume pot going to the 680k, through the bright high jack, which has a 1M to ground afterward, (so that's an attenuator, and Fred's scheme shows the same). Then the pair of 68k make a 34k grid stopper. The switch diagram above doesn't seem to match the layout diagram... note the 680k has both leads on the switch in the layout. Where is this 470k grid stopper you are speaking of?

[norburybrook]

Marcus, right so in that schematic above it shows the wiper of the gain/volume pot going to the 680k, through the bright high jack, which has a 1M to ground afterward, (so that's an attenuator, and Fred's scheme shows the same). Then the pair of 68k make a 34k grid stopper. The switch diagram above doesn't seem to match the layout diagram... note the 680k has both leads on the switch in the layout. Where is this 470k grid stopper you are speaking of?

On the phase inverter pin 7.



M

[fred.violleau]

@Marcus, I didn't use the 470k grid stopper on the PI since I did add a 1 Meg Master Volume. Did you try different positions on the NFB switch? With the raw position (aka no NFB) it gets pretty loud and ferocious. I did put 470 Ohms 3W resistors on the 6V6s to tame the blocking distortion. It is all pretty much stock Rob's modifications.

@Guy, thanks for the kind words !

@Martin, indeed, Rob's picture switch wiring does not match the layout wiring. I did follow the layout. In this mods, Rob refers to a great addition in conjunction with the switch which is adding a 470k grid stopper on the PI entrance, or adding a 1 meg Master Volume to avoid blocking distortion. I went the MV way, and I love it !

@Marcus, you don't seem to get as much distortion as I do though. Great loop BTW, love this daily morning Rendez-vous, always tasty playing and great tone !

Fred.

[ChopSauce]

That definitely makes for a desirable (not so) little amp. Thanks for sharing all that information - again!

Now, I (also) want one, though...

[norburybrook]

@Martin, indeed, Rob's picture switch wiring does not match the layout wiring. I did follow the layout. In this mods, Rob refers to a great addition in conjunction with the switch which is adding a 470k grid stopper on the PI entrance, or adding a 1 meg Master Volume to avoid blocking distortion. I went the MV way, and I love it !

@Marcus, you don't seem to get as much distortion as I do though. Great loop BTW, love this daily morning Rendez-vous, always tasty playing and great tone !

Fred.

Fred,

so you wire like the layout picture with the 680 across the bottom 2 pins ? ...

When I looked at the actual Photo of Robs amp it seemed to match the photo switch layout NOT the full amp layout. I need to revisit this. It's seems to work as excepted I thought I'd be into high gain territory though cascading , at the moment it's more or less acting a like a master volume only..ah that just came to me...so I don't think it's cascading at the moment I think it's working like a gain and master volume.

Ok it's funny how just going through it you realise what's happening


thanks for the kind words Fred. I enjoyed your playing on this thread hence me wanting to tweak my amp

I'll report back. Hope this isn't derailing your thread.


edit: Looking at this it seems the jumper the the 680 resistor are reversed between the picture and the layout. I'm crap with switches so not sure what that means.


M

[martin manning]

Marcus, maybe this will help? I marked up Fred's mark-up to show the layout for a 3PDT switch, and fixed the speaker connections.

[fred.violleau]

@Marcus, Martin's numbers match exactly what I did.

I did use the 680k resistor. My previous build has a Tweedle Dee bright channel as channel 1. It puts out way too much signal to feed the loop FX without overdriving, so I had to tame it down with a trimmer sending part of that signal to the ground. Hence I was not surprised when I saw it on Rob's schematic

If you added a 470k resistor on the PI entrance, it should act as MV already, so you don't need an extra one. Volume control of each channel are adding More volume, but with a MV then these act as gain controls, and MV act as it should. I will try and record something quick at noon today so you can hear how ferocious this beast can growl

I think you are almost there Marcus, a few solder joints away from serendipity !

Fred.

[fred.violleau]

A quick thought about the switch (which I too spent valuable time trying to understand the signal path...) : When in use, you need to plug into channel one since channel 1 signal is being fed into channel 2 through the jack grounding tip. If you keep using channel 2, you will not get the cascading effect. I am sure you got that already... But just in case

EDIT: BTW I ordered a celestion Rocket 50, and I am eager to try it!
Best sound so far was through my 2x10 prosonic celestion speakers.

Fred.

[fred.violleau]

Here is a link to the a video showcasing the different combinations between channels 1 and 2 with the three stages of NFB.
Video is a bit long, captured with a phone, and I am a bit too excited, I guess that little boy in me enjoying overdrive never gets old
I go from early break up into mild overdrive, and then it some heavy distortion up until blocking distortion, for the sake of the exercice.
I don't think Tweed amps were made to venture into RATM territories... but you can still have some fun !
Let me know what you think!

Fred.

[norburybrook]

Marcus, maybe this will help? I marked up Fred's mark-up to show the layout for a 3PDT switch, and fixed the speaker connections.

Martin ,

Thanks but that's even more confusing from the point that it's totally different from the other 2 now

I have mine wired like the Photo of the switch with the labelling and I think Rootz has his wired like the layout drawing and yours is different again.

are you numbering 1-2-3
4-5-6
7-8-9

with your drawing?



M

[martin manning]

Yes, rows left to right, top to bottom. Fred says my drawing matches his amp.

[norburybrook]

Yes, rows left to right, top to bottom. Fred says my drawing matches his amp.

Good It's Lucinda's birthday today so no soldering......

I shall return to this tomorrow I'm going to pick up my Gray Guitars telecaster tomorrow morning I had made last year. they're shaved the neck down a bit for me as I felt it was a little too chunky so I can get this together with my newly fettled guitar tomorrow


thanks fellas


M