What are your favourite blues breaker mods?

[neiltheseal]

Hey everyone. I recently put a blues breaker together and I love it. Probably way more than my king of tone clone.

I'm thinking of modifying it and wanted to know what everyone's favourite mods are.

I'm planning:

• presence control (like king of tone)
• hard clipping on/off switch (like king of tone)
• boost of some sort to increase volume
• a way to increase gain

Some questions:

1. It's very quiet (which I know is a known issue) so I tried a jfet boost at the end of the circuit and this helped a lot. I noticed that the JHS Morning glory includes this. Is there any benefit to adding the boost before the volume rather than after?
2. Would there be a benefit to adding the boost at the start or before the gain stage?
3. Would a mosfet boost work just as well?
4. How do I increase the gain without just adding clipping diodes?

Thanks in advance for any assistance.

 

[jesuscrisp]

1) Depends. The pedal running full blast might get you some extra JFET breakup if the volume is after the boost. If it's before the boost it will be likely cleaner and also give you consistent output impedance.

2) If you want more distortion/compression yes, but you're mostly overdriving the first half of the gain stage harder.

3) Yes.

4) There already ARE clipping diodes but I guess you mean other than adding hard clipping diodes.
As the BB and other Marshall pedals have kind of a dual gain stage with a bunch of variables, there's multiple ways:
- add a boost circuit in front
- increase gain in the first op amp stage by adding a resistor between inverting input and lug 1 of the gain pot
- increase gain in the first op amp stage by using smaller gain filter resistors, but also adjust the caps accordingly (e.g. replace the 27K and 33K with 2K7 and 3K3, increase the 10n caps to 100n
- increase gain of the first stage by using a larger value gain pot (like 250K), but keep in mind that you have to adjust the feedback resistor of the second stage as the pot also factors into the gain calculation of that stage
- increase the size of the 220K resistor in the 2nd op amp stage
- decrease the value or jumper the 6K8 resistor in series with the clipping diodes in the 2nd op amp stage
- connect lugs 2 and 3 of the gain pot so the second stage is always at maximum gain.
- decrease the 10K resistor between the 2 gain stages (although I really wouldn't recommend going much smaller than 10K there, plenty of other solutions as you see above.

Otherwise look at the gain level switch in the Wampler Pantheon schematic.

 

[neiltheseal]

thanks so much for this. Lots of great information here. Looks like I’ll have to try these out to see what sounds best.

 

[Feral Feline]

thanks so much for this. Lots of great information here. Looks like I’ll have to try these out to see what sounds best.

If you try the boost before and after and can't decide where it should go because you like it both ways...

Best of both worlds:
Stick the boost on a flip-flop switch so you can have it before or after.

You could have the boost on separate footswitch, or have it always on but still have the order switcher.

Separate:

 

[music6000]

1) Depends. The pedal running full blast might get you some extra JFET breakup if the volume is after the boost. If it's before the boost it will be likely cleaner and also give you consistent output impedance.

2) If you want more distortion/compression yes, but you're mostly overdriving the first half of the gain stage harder.

3) Yes.

4) There already ARE clipping diodes but I guess you mean other than adding hard clipping diodes.
As the BB and other Marshall pedals have kind of a dual gain stage with a bunch of variables, there's multiple ways:
- add a boost circuit in front
- increase gain in the first op amp stage by adding a resistor between inverting input and lug 1 of the gain pot
- increase gain in the first op amp stage by using smaller gain filter resistors, but also adjust the caps accordingly (e.g. replace the 27K and 33K with 2K7 and 3K3, increase the 10n caps to 100n
- increase gain of the first stage by using a larger value gain pot (like 250K), but keep in mind that you have to adjust the feedback resistor of the second stage as the pot also factors into the gain calculation of that stage
- increase the size of the 220K resistor in the 2nd op amp stage
- decrease the value or jumper the 6K8 resistor in series with the clipping diodes in the 2nd op amp stage
- connect lugs 2 and 3 of the gain pot so the second stage is always at maximum gain.
- decrease the 10K resistor between the 2 gain stages (although I really wouldn't recommend going much smaller than 10K there, plenty of other solutions as you see above.

Otherwise look at the gain level switch in the Wampler Pantheon schematic.

or, Build the Parthenon:

Parthenon Overdrive - PedalPCB.com

Compare to Wampler Pantheon

www.pedalpcb.com

 

[jesuscrisp]

or, Build the Parthenon:

Parthenon Overdrive - PedalPCB.com

Compare to Wampler Pantheon

www.pedalpcb.com

Funnily enough I think the best tones in the Pantheon are on standard gain and clipping. Didn't find the extra gain switch to add any think worthwhile, felt more like it was trying to achieve something the pedals wasn't supposed to do, namely stupidly high gain. The bass knob, external presence and volume boost are cool and much needed features though for the KoT design.

 

[cdwillis]

In the stock circuit use a linear 100k for the volume pot instead of a logarithmic pot. It makes the volume a little easier to dial in since it doesn't have a lot of output to begin with.

Put a small cap like a 100pf or 220 pf in parallel with the 220k resistor to smooth it out a little.

Alternatively replace the 220k resistor with a 470k resistor for high gain. I'd definitely add a small cap in parallel with the 470k to tame some of the fizz if you try this.

 

[jimilee]

The pantheon is my favorite. It has #allthemods.

 

[Laundryroom David]

The pantheon is my favorite. It has #allthemods.

Gotta agree. I am not a BB fan at all. I had a pantheon, sold it, have regretted it since. Stock settings are great and the modified settings can do a lot which is fun. Rather than modding a stock BB, I’d just build a parthenon or maybe even a pot and kettle, though it gives me option paralysis lol.

 

[neiltheseal]

The Parthenon seems to be a favourite. I'll have to check that out. Can someone tell me what's going on with the gain swithh in the first gain stage?

It looks to me that the switch is forcing the signal into a 47k and a 1m resistor, and the switch moves to another 1m resistor? Am I reading this wrong?

Also is r6 and r7/8 there to increase gain or some other function?

 

[neiltheseal]

Any way so I did some testing today and these are the things that I think sound great:

• Mosfet boost at the start of the circuit
• Hard clipping diodes (like KOT). I think I like 2 and 4 symmetrical so may have a switch
• 33nf caps after the tone section (less ear splitting)
• 330k resistor in feedback loop of second gain stage
• replace the 27K and 33K with 2K7 and 3K3. Although I still have 10n caps there and not the suggestd 100n

 

[jesuscrisp]

Can someone tell me what's going on with the gain swithh in the first gain stage?

3 scenarios: switch going straight to the 47K resistor, jumping the 1M - least gain.
Switch putting the 1M resistor in parallel to the 1M resistor in the loop, resulting in 547K in the feedback loop - more gain.
Switch not connecting at all - 1M047 in the feedback loop - most gain.

I personally don't like this switch as it all just affects the first stage.


Your mods look good, having the 33n caps for the tone section probably helps as you make the tone way brighter by using 2K7 + 3K3 with 10n caps. The made in Korea Bluesbreaker that JHS worked off for the morning glory has a similar gain configuration, but he counterbalanced it by putting a larger cap in the feedback loop of the second stage with the hi-cut switch.

 

[music6000]

Funnily enough I think the best tones in the Pantheon are on standard gain and clipping. Didn't find the extra gain switch to add any think worthwhile, felt more like it was trying to achieve something the pedals wasn't supposed to do, namely stupidly high gain. The bass knob, external presence and volume boost are cool and much needed features though for the KoT design.

I never did a Mockup the first time around so I have listed it in Project Development:

 

[hamerfan]

Parthenon Overdrive Mockup Pedal

This is a Blast From The Past that I think needs to be mentioned! Blues Breaker with a lot more if you want it: https://www.pedalpcb.com/product/pcb169/

forum.pedalpcb.com

 

[neiltheseal]

3 scenarios: switch going straight to the 47K resistor, jumping the 1M - least gain.
Switch putting the 1M resistor in parallel to the 1M resistor in the loop, resulting in 547K in the feedback loop - more gain.
Switch not connecting at all - 1M047 in the feedback loop - most gain.

I personally don't like this switch as it all just affects the first stage.


Your mods look good, having the 33n caps for the tone section probably helps as you make the tone way brighter by using 2K7 + 3K3 with 10n caps. The made in Korea Bluesbreaker that JHS worked off for the morning glory has a similar gain configuration, but he counterbalanced it by putting a larger cap in the feedback loop of the second stage with the hi-cut switch.

Thanks for this, it's a good explanation and I can see it now.

I'm quite happy with the mods so far. The boost really makes it shine

I'll add a presence control as well as I think that's really helpful on the KOT, although I couldn't be bothered trying that out.

I'll have a go at adding a Pantheon high gain resistor but the pedal sounds great so far. I tried just touching a resistor between pin 2 of the IC and lug 1 of the pot but it did nothing. I assume this is because there is already a direct connection between these and it's being bypassed. Still I might try it out as I feel it needs just a touch more gain. I'm hoping to get it to at least tube screamer territory.

I think this will be my favourite drive pedal ( a spot which is currently held by my kingtone blues power clone). I wonder if a dul drive in the style of the King of Tone is worth doing? Probably.

 

[Dan0h]

This is my Favorite Blues breaker mod.. built several they all kick every other BB I’ve built out the door.

 

[HamishR]

Have to agree with that.

 

[neiltheseal]

Hey everyone, thanks for the feedback. I put my bluesbreaker together yesterday and it is awesome. Exactly what I was looking for. I made the following modifications:

• Mosfet boost at the end of the circuit (kept the sound I liked and boosted it. boost at the start of circuit changed the tone a bit). Makes it LOUD!
• Hard clipping diodes (like KOT). I used an on-off-on switch to go between 2 and 4 asymmetrical and no hard clipping
• Added presence control like KOT (again less ear splitting)
• 33nf caps after the tone section (less ear splitting)
• 330k resistor in feedback loop of second gain stage
• replace the 27K and 33K with 2K7 and 3K3.
• added a 1m trimpot beween lug 1 of the drive pot and pin 2 of the IC. This dramatically increases the gain when turned up and is equivalent to a dod 250 in grit. Although it oscillates at about halfway up so a 500k trimpot would have been better in hindsight. I'm glad this is a trimpot as I cant decide whether I like some gain here or none. Higher gain sounds good but it does lose some of the bluesbreaker character which was why I made this in the first place.

Anyway, I'm very happy with these changes. The bluesbreaker is great but I think it had some shortcomings that I have fixed (to my liking): it was too quiet, too shrill and not enough gain. Not anymore!

 

[paulbarrette]

In the stock circuit use a linear 100k for the volume pot instead of a logarithmic pot. It makes the volume a little easier to dial in since it doesn't have a lot of output to begin with.

Put a small cap like a 100pf or 220 pf in parallel with the 220k resistor to smooth it out a little.

Alternatively replace the 220k resistor with a 470k resistor for high gain. I'd definitely add a small cap in parallel with the 470k to tame some of the fizz if you try this.

I tried swapping the 220k for a 470k. It made a noticeable difference

Thanks
Pb