Badlander mods?

[JustPassingThrough]

Changing the 15k to a 39k would reduce the gain, which sounds like it's the opposite of what they're looking to achieve.

Have a look at the coupling caps between stages and see if they can be beefed up. That's an easy win for more low end passing through the signal. Maybe the cathode bypass cap could be increased in value but thats a messier way of doing it in my experience.

 

[bandit2013]

Well, I feel like a total A$$. My diagrams are all wrong at least the one indicating the Badlander has a cold clipper circuit. Signal path is the same, that was based on the tube task chart. It was my measurements I took while poking around the tube sockets to see what was what. Since I was curious to see what can be done with the amp on a preamp basis, I discovered my grave error, the Badlander does not have a cold clipper circuit. Instead I can see why it is called a Rectifier like no other, it does not have a Rectifier preamp circuit in it. I had to double check to confirm I was poking around with the Badlander, yep. It was not the Triple Crown. Besides that, I only had the TC50 out so I would be able to tell the difference.

OK, what I did find was this:

V1A plate resistance: 100k, power net E.
V1A cathode resistance: 3k

V1B plate resistance: 82.5k, power net D.
V1B cathode resistance: 1.5k

V3A plate resistance: 270k, power net D.
V3A cathode resistance: 3.3k

V3B plate resistance: 130k, power net D.
V3B cathode resistance: 1.5k

There is no question about V2 as a DC coupled cathode follower.
V2A pin 1 is connected to pin 7 (V2A plate to V2B control grid).

V4 having a cathode follower tube driven FX send buffer is an assumption. I can check that later.

Based on the resistor measurements and discovery of my mistake, that 15k resistor was actually a 1.5k ohm cathode bypass resistor. Also had to look at the resistor itself for its markings to confirm.

I was wondering why the Badlander sounded so close to the JP2C. In my opinion, it does to some extent, that was while I had the STR443 tubes in that amp.

Take a wild guess what the preamp is? The huge difference is where the tone stack sits and how it is driven.

The first 4 gain stages are basically the same as the Mark VII in crunch and VII modes.

The difference is the last gain stage has 130k ohm plate resistance that drives into a DC coupled tone stack driver. It is the V1B and V3A triode pair that comprise the Mark lead drive circuit. I did confirm this as I measured the resistors several times. That small decimal dot was difficult to see in the amount of light in that room.

This time I did not let the series name bias my thoughts, it is not a Rectifier amp in any way. The preamp is a hybrid of sorts, combination of a Mark lead circuit with a rectifier tone stack driver. Isn't that interesting.

I did not bother to measure the pot values. Most of them are on the small diameter size except for the gain pot.

Changing the 1.5k resistor to anything larger would be a mess. I can be wrong at times, this was sort of embarrassing. Not like I have the schematic for this amp. In other words, the Badlander is practically the same as the crunch and VII modes of the Mark VII. The difference is the tone stack does not immediately follow the lead drive circuit like the Mark VII , instead it gets boosted and then dumped into a cathode follower tone stack driver.

If you have a Bad, you can confirm it yourself. I am not claiming to be an expert and I make mistakes.

 

[bandit2013]

Changing the 15k to a 39k would reduce the gain, which sounds like it's the opposite of what they're looking to achieve.

Have a look at the coupling caps between stages and see if they can be beefed up. That's an easy win for more low end passing through the signal. Maybe the cathode bypass cap could be increased in value but thats a messier way of doing it in my experience.

Yes, that would, but if this circuit was there, it would increase the low end. No cold clipper circuit as I rediscovered that last night.

 

[bandit2013]

Well, I did get around to swapping out some preamp tubes. That did not achieve much except for a slight change in tone. Long plate 12AX7 in the phase inverter did improve the low end a small amount. The Mesa 1990 Chinese 6N4-J in V1 and V3 did raise the gain saturation a bit, had to dial back on the gain as I found the noon setting to result in difficult to control feedback.

Now I am curious what a Mr. Scary Mod or the V2 EVO would do in the V2 position. Anybody have a clue what that circuit is? One or two gain stages with the tone stack driver circuit? Still have not found any video content on that device used in the Badlander.

 

[afu]

I think playing with the bypass caps on the cathodes will give the wanted bass increases. Aiming for around 100 Hz or so on the -3dB point would be a compromise with getting it a little bigger.

For gain, the plate resistors could be increased. The Dual Rec and SLO begin with a 220k resistor on the first stage. That would mess up the clean channel, but gain increases downstream would be the next best thing. Even small increases make a difference.

Another thing those amps do is to add in series resistance heading into a stage. For example, Rectifiers have it after the gain pot as it heads into the grid of the second stage. It adds compression.

Another option is to choose a stage, (probably the final one for crush) and play with the interstage voltage divider prior to it. Dump less signal to ground and see if it's necessary to work backward to get some more from the one before. This amp presents a challenge, because it adds on stages to get progressively more modern and heavy from mode 1 to 3. Changing the interstage voltage divider will cause the middle mode to drive the tone stack harder. I'm not sure what that will do to the EQ.

But, really, you should probably just sell it and get something more suitable.

 

[bandit2013]

Not that this will make any difference. This is the Badlander corrected signal path. No cold clipper as I originally thought.

Here is the same thing but with respect to the Mark VII.

The Badlander also has a single inductor similar to that found in the Mark amps commonly used with the GEQ circuit. Not sure if this is used to preset a characteristic of the signal to emulate a Rectifier amp. Without the schematic, it would be foolish to go any further with this.

 

[starbelly]

I love my Badlander but am also in the same boat. I’m curious how the Mr. Scary mod would fare here!

 

[JustPassingThrough]

I love my Badlander but am also in the same boat. I’m curious how the Mr. Scary mod would fare here!

More gain will be simple to achieve, same with more bass. Like I said ages ago, increasing coupling cap value and lowering a cathode resistor will achieve those things with minimal fuss and be entirely reversible, or could even be put on a switch.

A schematic for this amp would be great but I doubt we'll see one anytime soon.

 

[bandit2013]

More gain will be simple to achieve, same with more bass. Like I said ages ago, increasing coupling cap value and lowering a cathode resistor will achieve those things with minimal fuss and be entirely reversible, or could even be put on a switch.

A schematic for this amp would be great but I doubt we'll see one anytime soon.

If the Badlander had a cold clipper circuit, perhaps that would help. It does not have a cold clipper, not with the measured resistor values are as follows:

V1A plate resistance: 100k, power net E.
V1A cathode resistance: 3k

V1B plate resistance: 82.5k, power net D.
V1B cathode resistance: 1.5k

V3A plate resistance: 270k, power net D.
V3A cathode resistance: 3.3k

V3B plate resistance: 130k, power net D.
V3B cathode resistance: 1.5k

The V1B and V2A circuit is a Mark lead drive circuit. V3B plate resistor is marked to be 100k but 130k was measured. I looked at my second Bad100, same values in that amp as well. I was only looking to see what tube sockets had the dc coupled cathode follower circuit, V2 since it is not mentioned in the manual that V2 is the tone stack driver circuit. Would be nice to know up front before finding out down the road that Russian tube you though sounded great at first sh!t the bed because it is not compatible with that circuit.

So please indicate what cathode resistor should be dropped to increase gain. Can you tell me what the load line change will be? How should I compensate for the shift? Must I change the plate resistor too?

I see nothing wrong with the Badlander as it is. Perhaps your experimentation with your Stiletto had merits, that amp needs some help as it was tuned for a different characteristic. I do not see any virtue of your comments here as this amp is different in design. Sure, no schematic available, however the one can simply measure component values while they are in the circuit. There will be some variances due to impedances (bypass caps if present.) The parts are not invisible so the markings on them can be used to confirm the measured values. Cathode resistors were measured from the tube socket to chassis ground. There could be other components managed with relays but the normally closed state of the unpowered relay was ok for quick measurements.

 

[JustPassingThrough]

Sure.

V3a is an easy target to lower the 3k3 to a 2k7 or lower, and easily done with a pot clipped in parallel to that resistor, find the setting you like, measure the pot, then install that value in parallel. Easy, and entirely reversible.

I'd guesstimate v1 will affect the clean channel as well which might not be what the op is looking for..

Word salad aside, lowering that resistor would boost the gain. I don't understand why you're so against it. At least op has something to work with but it would be more help to them and others if you shared the designators for the resistors.

 

[bandit2013]

Yeah, that would work. Not against it. The Badlander looks easy enough to work on anyways. Cool idea.

A Schematic for this amp would be ideal.

Do not use this for reference. It has some bad spelling and grammatical errors. I also corrected the reference of triode A and B and rewrote it based on how Mesa identifies the triodes which is different than the standard nomenclature. The post I placed after this has the corrections and proper Mesa triode references. I also corrected the errors or typos since I referenced V1B in the description of the second gain stage, it should have been V3B but that was wrong too. I cannot delete this but I will cross a line through the text as it is bad.

I marked one of the better pictures I have of the preamp. Yellow dots ID the cathode resistors and the blue with red center are the plate resistors. Also note that Mesa did not follow the V1A-V1B method assuming the reference of the 12AX7 pin out was correct. they reversed A with B due to ease of design. I do not want to fix the graphic as it was derived from Mesa's tube task chart in the manual.
For reference, the front of the amp would be to the right side of the image and down to the lower right side.

First Gain stage: V1B-pin 1: Plate resistor 100k, R19, Has a voltage reference letter of E marked next to it. this one is hidden by a coax cable in the image. Bottom right are of the image.
V1B -pin 3: Cathode resistor 1.5k, R17. This is the second one to the left of the ferrite bead.

Second gain stage: V1A-pin 6: Plate resistor 82.5k, R42 has a voltage reference letter of D marked next to it. this is on the bottom row next to a diode and relay, lower area about the center of the image. V1A-pin 8: Cathode resistor 1.5k R41. This is near the upper right are of the image, closest to the socket and next to two capacitors.

Third gain stage: V3B-pin 1: Plate resistor 270k, R48, has a voltage reference letter of D marked next to it. it is on the other side of the relay in relation to the plate resistor for the second gain stage. V1B-pin 3: Cathode resistor 3.3k, R49. in the lower left side. This would be the resistor to be paralleled with another to drop its resistance value.

Fourth gain stage: V3A-pin 6: Plate resistor 100k, R53, has a voltage reference letter of D marked next to it. In the upper left area of the image. Also in line with the orange bypass cap. V3A-pin 8: Cathode resistor 1.5k, R52. This one is tucked in between the orange bypass cap and the V3 socket

Note that the image above is for the early release of the Badlander. The one I got not too long ago has a different board revision. That one is Rev 7. The picture I took of that has a few of the parts hidden by some of the components but they seem to have the same reference designators and are in the same general location.

 

[bandit2013]

Just a note: When I measured the cathode resistance, it was from the cathode pin on the socket to the chassis itself (the unpainted area of the chassis that has the control pots mounted to it). I did identify the resistors from further probing to see if that was the only part in the circuit and not connected to other parts assuming they were controlled by relays based on voicing modes.

Here is the larger picture of the full internal gut shot for some reference if you need it. Note that the zoomed in image in the previous post was rotated 90 degrees. That yellow wire is the input signal. It has a ground wire running along with it in grey. Surprised it was not a coax cable. The Rev 7 board assembly is much the same.

First thing to point out, Mesa does not use the standard 12AX7 pinout for identifying triode A and triode B. I checked a few other schematics for reference. In standard form; Triode A uses pins 6,7,8 and triode B uses pins 1,2,3. Based on typical Mesa nomenclature, the triode that uses pins 1,2,3 is their reference to triode A and 6,7,8 is triode B. It is just a matter of preference really. I will stick with the reference that Mesa uses instead of the standard pinout used by the industry may make things easier to follow. The schematic should have the pin numbers of the triode shown. Per the standard form, the 12AX7 is shown like this. Just swap the A and B for reference to the Mesa labeling system. The standard pinout on the left and the MESA version on the right.

I copied this from the other post with changes using the Mesa version of the 12AX7 pinout. I also rotated the image to match the full picture above.

First Gain stage all modes: V1A-pin 1: Plate resistor 100k, R19, has a voltage reference letter of E marked next to it. this one is hidden by a coax cable in the image.
V1A -pin 3: Cathode resistor 1.5k, R17. This is the second one below the ferrite bead.

Second gain stage Crunch and Crush only: V1B-pin 6: Plate resistor 82.5k, R42 has a voltage reference letter of D marked next to it. It is next to D20 just above the relay. It is in the same row as the R17 and R19 above it. V1B-pin 8: Cathode resistor 1.5k R41. This is near the upper left area of the image, closest to the socket and next to two capacitors C35 and C46. I would assume that relay in that upper left may switch between one of the two cathode bypass capacitors depending on the mode for crunch or crush. This Gain stage is not used by the Clean mode.

Third gain stage Crush only: V3A-pin 1: Plate resistor 270k, R48, has a voltage reference letter of D marked next to it. it is almost in line with the V3 reference designator next to the socket. It is also just below the one relay. It is the 1/4 W sized resistor. V3A-pin 3: Cathode resistor 3.3k, R49. in the lower right side of the socket. It is right above D22 and D25. This would be the resistor to be paralleled with another to drop its resistance value. This circuit is bypassed with the crunch mode so it will only affect the crush mode.

Fourth gain stage Crush, Third gain stage Crunch, and 2 gain stage clean: V3B-pin 6: Plate resistor 100k, R53, has a voltage reference letter of D marked next to it. In the lower left area of the image. Also, it is in line with the orange bypass cap. V3B-pin 8: Cathode resistor 1.5k, R52. This one is tucked in between the orange bypass cap and the V3 socket.

What is not shown is the clean channel, that basically just uses V1A and V3B and bypasses V1B and V3A triodes.

 

[rarebitusa]

Well I really like my Badlanders gain structure. It has plenty for me, however some always want more which is fine. Happened to come across this one

Mr Scary Mod

A resistor change is surely a cost effective approach especially if one is skilled with a soldering iron. Hijacking a tube for something that plugs in is attractive and simply reversible if money is less of an object. Personally I find that a GEQ in the loop and a low drive pedal boost works well to shape the tone, but I'm not chugging alot either.

 

[bandit2013]

Cool find.

Hmm, just realized that the Mr. Scary mod trick would work but will also affect the clean channel as that passes through the tone stack driver. Not that it matters much. Using this is not to make the amp cleaner, just add more bit and gain to the tone structure.

I only have one question that I cannot find the answer too. How well does it fit in the head? V2 is towards the front of the amp about at the center. May have to let the power tubes cool down before reaching in to adjust the gain on the Scary mod. Would be nice to see some pictures of it installed in the Badlander or even a Mesa Dual Rectifier. Adapters are required to fit Mesa as the sockets sit deeper in the chassis than say a Marshall. They are available from Legendary tone website.

Cool that it works though. I thought Kyle Bull made a video before "I modified the Badlander" was the title but could not find it. It was on the 50W version and not the 100W versions he was demonstrating in the video.

 

[edge59AlnicoIV]

Does anyone have a Badlander schematic? I'm checking out a friend's that we want to make sure the voltages are right and have a better understanding of how it works

 

[bandit2013]

Well I really like my Badlanders gain structure. It has plenty for me, however some always want more which is fine. Happened to come across this one

Mr Scary Mod

A resistor change is surely a cost effective approach especially if one is skilled with a soldering iron. Hijacking a tube for something that plugs in is attractive and simply reversible if money is less of an object. Personally I find that a GEQ in the loop and a low drive pedal boost works well to shape the tone, but I'm not chugging alot either.

You so know this is tempting just to get one and try it out. My grid slammer or Flux-drive is an easier solution for me as I do not have to spend money as I already have it.

 

[bandit2013]

Does anyone have a Badlander schematic? I'm checking out a friend's that we want to make sure the voltages are right and have a better understanding of how it works

If you get your hands on such, I would be interested in a copy.

I doubt there are any schematics leaked out on this amp yet.

Are you converting the power transformer to an export version? All that I have is the tube task chart along with some resistor measurements on the basic preamp circuit. I did not take any voltage measurements as I am not fond of poking around a high voltage amp without the schematics to review where to stick the probes.

I have posted above what information I have. As for the power tubes, no access from the inside of the amp to the pins on the power tube sockets. It is buried under the boards. So if you are looking to measure the plate voltage and currents, a bias probe is necessary. You would probably have to remove the chassis from the shell to get them into place. The Badlander like other Mesa amps runs a fixed bias so there is no point of adjustment. That fixed bias is good for the Mesa EL34 tubes STR447 or STR446 and probably best if the bias color is green, grey, or blue. What the plate currents and voltages are, I have no clue. I would avoid the use of NOS EL34 like Mullards or Siemens types as they may be sensitive to plate voltages above 425 (the limit is based on the applied screen voltage, plates can handle up to 800V in push-pull pentode, I believe the limit is 500V in triode. Badlander is running Pentode 100W, or 50W and triode for 25W. The Badlander runs probably 450V or a bit higher like 470V but as I said before, I have not measured any voltages. It is just an assumption as it is based on existing schematics one can find doing a simple search. Badlander is a hybrid, a combination of a Mark amp and a Rectifier amp. Mark like on the first 4 gain stages, and after that it is all Recto-ish.

6L6GC tubes when switching the bias switch to that tube type will reduce the volume a bit. Again, with the bias colors, green, grey, or blue. The colder tubes in the reds or yellows are a bit less desirable unless you want to neuter the amount of distortion you get from the amp.

No schematics available to the general public. I fall into that category too. If you do find them, I would advise against making them public, Gibson and Mesa have a good law firm and will not hesitate to sue on sharing of their intellectual property.

 

[kmanick]

 

[Snicksound]

View attachment 3432

So I was curious about your drawing that implies FOUR gain stages before we get to the tone stack circuit, which is one more than a Dual Rectifier and without a cold clipper that would be an insane amount of gain (unless a lot of it is being dumped).

So I got to thinking... what if the whole front end is really a Mark???

And I'm starting to think that might be it.

See on that picture, the actual tone stack is near the controls: a quad of 22nF caps, two 500pF caps and two 33.2k resistors. That's textbook a pair of Marshall tone stacks (notice, not 39k or 47k, but good old 33k).

So then... what are those to the right of the picture? Look a lot like tone stacks as well! One has a 500pF "treble" cap then a 22nF and 47nF caps, the other has both a 500pF and 250pF (switched or paralleled? have to check that out), a 22nF and 10nF cap. Add in the few resistors around and that looks like a pair of "fixed tone stack"

So Badlander seems to be: Mark front end, into Marshall style cathode follower and tone circuits.

Interesting...

I have to measure out a few things, but the key to a "more gain mod" might be there, tweaking some of those values to let more signal through?

Also, one could change the first plate resistor to a 220k or 270k (I personally prefer 100k, less compressed IMHO).

I don't see a need for more gain, but to each their own. I'm happy with just the Crunch mode and an extra OD pedal from time to time.

As for "more lows", well the NFB wire is fairly easy to spot (single grey wire that goes from the speaker jack daughter board to between V2 and V5), if you know what you're doing you can simply insert a 500k-1M pot in between with a 4.7nF-ish cap and bam you got a Depth/Resonance control. Could couple with a NFB interrupt switch if you want something like the Modern mode on the Recto.

But note the small inductor close to it, looks like there's already a fixed resonance boost in the form of an inductor across the tail resistor (which is really the Presence pot). Perhaps tweaking the inductor value could do it too (but adding a Resonance control is easier, no need to take the board out, however you need to drill a hole, unless you MacGyver something internal).

 

[rarebitusa]

So I got to thinking... what if the whole front end is really a Mark???

Well to my ears it sure sounds like alot of Mark DNA is embedded in this one.

I don't see a need for more gain, but to each their own. I'm happy with just the Crunch mode and an extra OD pedal from time to time.

Yea with you on that. Depending on the desired tone I find either an OD or a GEQ in the loop easily provides enough "tone shaping" to get there.

As for "more lows", well the NFB wire is fairly easy to spot (single grey wire that goes from the speaker jack daughter board to between V2 and V5), if you know what you're doing you can simply insert a 500k-1M pot in between with a 4.7nF-ish cap and bam you got a Depth/Resonance control

The secret weapon Depth/Resonance. I added that to my Stiletto... simple and so effective. I never understood why Mesa didn't add this to their amps.