New at runoffgroove.com: Thunderbird

[Giglawyer]

Could this be modded to emulate a Marshall Super Bass, or are the circuits too different?

Was this some sort of thread-killing question?

[Gary]

Was this some sort of thread-killing question?

Maybe?  For two reasons.
1) Asking about mods before having built/breadboarded/tried it is maybe a little off-putting?
2) What you are asking for was alluded to in the posted article, particularly the part about the function of the "Tone" control (beginning sixth section down).  This functions as a sort of variable "jumper" between the Bright and Normal channels of the target amp.  As you know, the Normal channel of that amp is much the same as the Super Bass (depending on what specimen of SB you've seen).  Turn the Tone knob all the way down and you should find what you are looking for.  If not, then the time would be right to discuss making changes to the circuit.

I encourage you to breadboard the circuit if at all possible.  It is non-committal that way.

[Giglawyer]

Was this some sort of thread-killing question?

Maybe?  For two reasons.
1) Asking about mods before having built/breadboarded/tried it is maybe a little off-putting?
2) What you are asking for was alluded to in the posted article, particularly the part about the function of the "Tone" control (beginning sixth section down).  This functions as a sort of variable "jumper" between the Bright and Normal channels of the target amp.  As you know, the Normal channel of that amp is much the same as the Super Bass (depending on what specimen of SB you've seen).  Turn the Tone knob all the way down and you should find what you are looking for.  If not, then the time would be right to discuss making changes to the circuit.

I encourage you to breadboard the circuit if at all possible.  It is non-committal that way.

I think you may have misunderstood my question.  I was trying to inquire as to whether the Marshall Super Lead and Super Bass circuits were so similar that this project could be used to emulate a Super Bass amp.  If the answer is "I don't know," that's fine.  I certain didn't mean to offend or be "off-putting."  I am also not asking anyone else to mod  or change the circuit.   I am just wondering if this would be a good staring point to experiment with for a Super Bass (or not).  I will read the article again. 

[Gary]

Let me try once more:
Turning the Tone knob all the way down functions like using the Normal input of the amp.  The Normal input of the amp is essentially the same as the Super Bass.

[electrip]

So if a Split-Cathode and a Shared-Cathode for V1 just sound and behave the same there is no need to mod.

electrip

[stm]

Project text has been updated with some frequency response graphs.

[Caferacernoc]

I find it interesting that diodes in the feedback loop are used for "hard clipping" and are then followed by diodes to ground for 'soft clipping". Not that I disagree. I think tube screamer type pedals only sound like like "soft overdrive" because of the pre distortion bass cut.

[YouAre]

I find it interesting that diodes in the feedback loop are used for "hard clipping" and are then followed by diodes to ground for 'soft clipping". Not that I disagree. I think tube screamer type pedals only sound like like "soft overdrive" because of the pre distortion bass cut.

Stark difference here is that the opamp with feedback loop clipping diodes setup is inverting, whereas the tubescreamer is non-inverting. I feel like the inclusion of the "clean" signal being mixed with the clipped signal in non-inverting opamp stages has a big impact on the sound.

[azrael]

Very cool, just saw this project, and it's very quickly moved up the top of my list of things to build. Love ROG circuits!

[sajy_ho]

Sorry for hijacking an old thread; I'm gathering parts for this project and I couldn't find the 1N5711 diode.
The only Schottky diodes I could find around are 1N5819 and BAT43. Can I use one of these?
Is there something speacial about the 5711 in that place or it's just the forward voltage? I mean if it's only the forward voltage that matters here, so I probably could use a silicon diode here, am I right?

1n5711 data: http://www.st.com/st-web-ui/static/active/en/resource/technical/document/datasheet/CD00000759.pdf

[bool]

MY gut says go with BAT43.

Of course, wait for someone else's "second opinion" before you make the final decision.

[samhay]

1N5711 is not critical, you just want something with a low Fv -
http://www.diystompboxes.com/smfforum/index.php?topic=109465.msg1011898#msg1011898

[sajy_ho]

1N5711 is not critical, you just want something with a low Fv -
http://www.diystompboxes.com/smfforum/index.php?topic=109465.msg1011898#msg1011898

Thanks Sam, I guess I should search more before posting.
So probably I go with BAT43

[henkiejan]

The Thunderbird is a great pedal, but has imho one major disadvantage: it's noise level.
Options to bring this level down, besides shielding, no vero, etc, could be to decrease the resistor values around the opamps or to decrease the numer of components altogether.

One of the first questions that popped up was: what is the function of the 10M resistor to ground at the input? Isn't the input impedance decreased (to 909 k) by using the 10M resistor to ground parallel to the 1M to Vref? Could anyone explain, please?

[B Tremblay]

The Thunderbird is a great pedal, but has imho one major disadvantage: it's noise level.
Options to bring this level down, besides shielding, no vero, etc, could be to decrease the resistor values around the opamps or to decrease the numer of components altogether.

How are you assessing the noise level? With your own build of the circuit or by demo clips?

[henkiejan]

How are you assessing the noise level? With your own build of the circuit or by demo clips?

My own build, on vero, based on a verified layout on Guitar FX Layouts. Input wires have been shielded, but it's still a bit too noisy for me.

I'm trying to learn each day. I'm curious why in many effects the resistor values around op amps are so high (in theory adding noise), and why certain components are there in the first place.
An answer would be much appreciated.

[B Tremblay]

I'm sorry to hear that the noise is excessive to your ears. It is a high gain circuit and necessary to employ best practices for minimizing noise.

Reading RG Keen's Tech articles will provide better answers to your more general questions than I could ever hope to offer.

[strassercaster]

1N5711 is not critical, you just want something with a low Fv -
http://www.diystompboxes.com/smfforum/index.php?topic=109465.msg1011898#msg1011898

Thanks Sam, I guess I should search more before posting.
So probably I go with BAT43

i am just minutes from finishing mine . i didnt have and couldnt find any 1n5711 i substituted some 1n270 germaniums  they have a forward voltage of .380 on my meter. do you think ill be ok ? i just have to hook up my power amd we shall see . i did the tagboard layout and I cant wait to try it. i made a modded marshall shredmaster/hyde and love it. I am hoping this will even be better if possible . Runoffgroove has some amazing circuits . Id like to thank them for these wonderful designs . Thank You

[mp3j3rk]

i am just minutes from finishing mine . i didnt have and couldnt find any 1n5711 i substituted some 1n270 germaniums  they have a forward voltage of .380 on my meter. do you think ill be ok ? i just have to hook up my power amd we shall see . i did the tagboard layout and I cant wait to try it. i made a modded marshall shredmaster/hyde and love it. I am hoping this will even be better if possible . Runoffgroove has some amazing circuits . Id like to thank them for these wonderful designs . Thank You

I am pricing parts out for this build and am weighing the alternatives for the 1N5711.  How did your 1N270 work out?

[strassercaster]

i am just minutes from finishing mine . i didnt have and couldnt find any 1n5711 i substituted some 1n270 germaniums  they have a forward voltage of .380 on my meter. do you think ill be ok ? i just have to hook up my power amd we shall see . i did the tagboard layout and I cant wait to try it. i made a modded marshall shredmaster/hyde and love it. I am hoping this will even be better if possible . Runoffgroove has some amazing circuits . Id like to thank them for these wonderful designs . Thank You

I am pricing parts out for this build and am weighing the alternatives for the 1N5711.  How did your 1N270 work out?

Sorry i didnt see your wuestion. I eventually got the 5711 and put my 1n270 back in it is a taf warmer and less edgy i preferred it to the 5711. i tiggled it and could hear a difference