Tweedle Dee - 4 component mod for Dumble Classic tone stack

[bluesfendermanblues]

Having rebuild my 5e3 clone to Tweedle Dee specs., this little amp is my grab and go amp, but like most users I tend to favor the "Bright" channel with the tone pot and been looking for a simple way to mod the "Normal" channel for a Dumble Clean stack sound.

Here it is:

Simply add a (4 component) t-notch stack in front of the normal channel volume pot. I have done a lot of experimentation in order to arrive at the "correct" values.

You take a 100k in series with a 220k resistor bridged by a 1.5n (1500pf) cap. The connection point between the two resistors are connected with a 4n (4000pf) to ground. The 100k resistor is input and the 220k is the output.

Connect this little circuit between the 22n (coming from V1a) and the Normal volume pot. (I should add that I have reversed the in/out log on both pots, so the are wired like normal volume pots. Hence, the t-notch stack 'sees' 1M ressistance.)

If you want more scooped mids a la fender black face scooped sound, you reverse the circuit and make the 220k the input and the 100k the output.

Thats it.

Background:
How did I arrive at the "Correct" values?. Its a matter of taste of course, but being a strat player I prefer the Classic stack (330p, 100k slope, 47 mid, 100n bass). The skyliner is more adapt for humbuckers IME.

We've had a lot of tone stack discussions on the amp garage over the years, but IMEO in the end its a matter of turning the knobs until you arrive a sound to your liking. BTW. I never use the bright, mid, deep or rock/jazz switches

As an experiment dial your knobs to your favorite setting and take your multimeter to measure the actual resistance on the bass and mid pots.

I have found that the value of the pots at my favorite setting" in the skyliner vs the classic stack is very minor - in real life. Using KA potentiometer you will find the a 250KA dialed to "4" (11 o'clock) has a similar ohm resistance as a 500KA dialed to "4". Maybe that just me, but I think a lot of confusion stem from us comparing schematics.

On my amps with classic stack, I rarely touch the bass pot, I usually sounds best at "4" and when I measure the ohm value on the pot (with wires disconnected) "4" equals a value of 100k. Same with the mid control, I rerely touch it and it is also usually on "4" and the equals 40k.

Before I put thenew t-stack in the tweedle dee amp, I tried an interim simplified tone stack with a 250KA treble pot wired with a 100k for bass and a 39K for mids. Sounded fine to me. Never missed the bass and mid pots. So why not settle with a this simplified tone stack?......because is takes out a lot of db's, making the "Normal" channel weak in comparison with the "Bright" channel (not a problem in usual ODS amps with more tubes).

This sent me looking for a more efficient 'tone stack'. The t-notch only dampen the mid and bass where you want the damping but leaved the higher freqs nearly untouched. Therefore, if you - like me - rarely touch the tone controls and can live with fixed equalisation, the t-notch is a good solution.

If you like the Skyliner better, You substitute the component values in order the get more low mids etc.

Have fun!

You can use the duncan tsc tone stack calculator "Big Muff" tone stack to simulate the right values. All you have to do is set the top resistor to 10m Ohm, which in effect takes it out of the circuit.

[dcribbs1412]

Thanks bluesfendermanblues
have my Twe Dee on the bench
this sounds interesting
may give this a shot
appreciate your work

D

[10thTx]

Like this??

With respect, 10thtx

[bluesfendermanblues]

Like this??

With respect, 10thtx

Almost.

The 15n bridges both resistors

[bluesfendermanblues]

....and remember the neat trick.

If you reverse the 100k and 220k - you get instant blackface sound with more mid scoop.

[10thTx]

Yes, that makes sense! Thank you for sharing.

With respect,10thtx

[CHIP]

Thanks for this Bluesfendermanblues.

[shane]

Yes Bluesfenderman thats a very cool mod

'Course theres no reason you cant have it both ways round:

[bluesfendermanblues]

Wow, elegant solution!

Btw. I have made further trails, and if you want Skyliner sound, you all you have to do is change the the 4n to 2n - changing the mid dip from 350hz to 620 hz.

Would be cool having it 'all' on a switch; Skyliner, Classic, Blackface

[ayan]

I've enjoyed reading the post, cool stuff. By the way and for what it's worth, the Skyliner mid dip sit around 460 Hz according to a nice spectrum analyzer shot from Gary Johnson of a Skyliner amp with all controls at 12 o'clock.

Cheers,

Gil

Wow, elegant solution!

Btw. I have made further trails, and if you want Skyliner sound, you all you have to do is change the the 4n to 2n - changing the mid dip from 350hz to 620 hz.

Would be cool having it 'all' on a switch; Skyliner, Classic, Blackface

[shane]

Here's a couple of ways you might get all three (I hope!).

[10thTx]

Just another variation.

With respect, 10thtx

[bluesfendermanblues]

I've enjoyed reading the post, cool stuff. By the way and for what it's worth, the Skyliner mid dip sit around 460 Hz according to a nice spectrum analyzer shot from Gary Johnson of a Skyliner amp with all controls at 12 o'clock.

Cheers,

Gil

Hi Gil, Interesting - For me (Strat guy) the 'sweet spot' is with the bass and mid a tad lower than 5 and the treble on 6-7. Do you think the dip sits at 460Hz at these settings? could be interesting to know - maybe one should try running some pink noise through the amp and check the curves of the different circuits suggested above on a spectrum anl. like Gary Johnson. So far, I have arrived at the above mentioned values with a combination of calculations and trial and error, soldering components in and out of the circuit and playin' playin. What I hear from the amp is pretty close to what I hear from my other D clones. It's like building cross-overs for Hifi Speakers....you wear out the carpet

Funny thing about component values...if you use a 47n for mid in a fender BF (twin, princeton) the dip sits at 350 Hz, which probably suited 2x12" or 1x10". I you use a 22n like in a Fender Super the dip sits at 550 Hz which probably suits 4x10".

I have an 80's celestion G80 in my tweed. could be that I tweaking to this speaker and my strat. So as usual your mileage may vary .

[ayan]

Hi,

The treble pot can shift the notch right to left to an extent, but I don't think the middle or bass shift anything left to right. Turning up the treble will shift the notch a bit to the left, so I think you would be even a bit lower than 460 Hz with the treble turned up in a Skyliner stack.

G.

Hi Gil, Interesting - For me (Strat guy) the 'sweet spot' is with the bass and mid a tad lower than 5 and the treble on 6-7. Do you think the dip sits at 460Hz at these settings? could be interesting to know - maybe one should try running some pink noise through the amp and check the curves of the different circuits suggested above on a spectrum anl. like Gary Johnson. So far, I have arrived at the above mentioned values with a combination of calculations and trial and error, soldering components in and out of the circuit and playin' playin. What I hear from the amp is pretty close to what I hear from my other D clones. It's like building cross-overs for Hifi Speakers....you wear out the carpet

Funny thing about component values...if you use a 47n for mid in a fender BF (twin, princeton) the dip sits at 350 Hz, which probably suited 2x12" or 1x10". I you use a 22n like in a Fender Super the dip sits at 550 Hz which probably suits 4x10".

I have an 80's celestion G80 in my tweed. could be that I tweaking to this speaker and my strat. So as usual your mileage may vary .

[bluesfendermanblues]

Just another variation.

With respect, 10thtx

Brilliant !