Mesa Boogie Mark V sounds fizzy in Channel 2 Crunch, Channel 3 IIC+ and Mark IV mode

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Hektor

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Hello,
I just got my first Mesa Boogie. Decided to get the Mark V because of the versaitility.
Before that i used a Fractal Audio AX8. Because i liked the Mesa models the most i decided to buy the real deal.
After spending all day with it, it seems to me something is wrong with my Amp. The channels and modes listed above dont sound anywhere near the sound demos i see online or even the fractal audio models.
It seems like there is no where near enough gain on all those modes (granted, i am using a strat) and there is alot of fizzyness which i can not dial out. There is no fizzyness on all the YT videos.
Might there be something wrong with the tubes? The power amp tubes seem to be fine. I also tried dialing back Gain, Treble and Presence. but as soon as I do that it sounds like a blanket over the amp, or i do not have enough gain.
As soon as i switch into the Mark 1 mode or the Extreme mode, there is no fizzyness whatsoever.
All help will be appreciated.
 
So in the manual there are a number of suggested configurations "factory sample settings" Curious if you have tried any of those to start with.
 
Hello,
I just got my first Mesa Boogie. Decided to get the Mark V because of the versaitility.
Before that i used a Fractal Audio AX8. Because i liked the Mesa models the most i decided to buy the real deal.
After spending all day with it, it seems to me something is wrong with my Amp. The channels and modes listed above dont sound anywhere near the sound demos i see online or even the fractal audio models.
It seems like there is no where near enough gain on all those modes (granted, i am using a strat) and there is alot of fizzyness which i can not dial out. There is no fizzyness on all the YT videos.
Might there be something wrong with the tubes? The power amp tubes seem to be fine. I also tried dialing back Gain, Treble and Presence. but as soon as I do that it sounds like a blanket over the amp, or i do not have enough gain.
As soon as i switch into the Mark 1 mode or the Extreme mode, there is no fizzyness whatsoever.
All help will be appreciated.
It sounds like you have a pre-amp tube issue. If reverb doesn’t work, it’s either v4 or v5. If Channel 2 works (which is Mark 1 mode) but channel 1 isn’t clean and strong, check v3 - possibly v3B is bad).
 
I have a Mark V 90, a JP2C, a Mark IV, (and a Diezel VH4 and Marshall plexi) I have 25 guitars. I find it much harder to get a full gainy sound with any of my strats with any of these amps, and there are big differences between them, much more than any of my humbucker guitars. I have found that I need a boost pedal and EQ to get a comparable sound with a strat. Do you have a guitar store you can go try out another Mesa amp?
 
This is a long response, I almost replied yesterday after seeing your post but had to think about what may be the issue.

You wrote: After spending all day with it, it seems to me something is wrong with my Amp. The channels and modes listed above don't sound anywhere near the sound demos I see online or even the fractal audio models.

Modeling amps may be close but are not the same thing as the real deal. YT videos, I generally could never get any of my amps to sound like those either, depends on how it was made. If it is a raw method that did not use any DAW software or units used to translate the amp into something it is not like the Two Notes torpedo and stuff like that tend to make it sound different than reality. Also, many may be using extra stuff in the signal chain so it may not be accurate. I tend just to use one effect when making video and that is a Strymon BigSky reverb pedal. Mic on cabinet but buffered through a Scarlotte Dynamic Octo Preamp, that gets routed to a Zoom H6 hand held digital recorder so I can make use of the consumer grade line level out to feed directly into the video camera. I try to keep it as real as possible. Again, I have never been able to replicate the sound, tone or character with the amp in question (Badlander, Mark V90, JP2C, Mark VII, Royal Atlantic, Triple Crown 100 and 50, Roadster, MWDR, and California tweed.) Even the Mese Video content is unreachable.

However, the amp should not be fizzy as you described, even with a Stratocaster. I have two but they do not have single coils anymore. Both are using Zexcoil pickups which are like a humbucker of sorts but has 6 coils vs 2 or one. My other guitars in the HSS formats use single coil pickups and I do not get fizzy notes with the Mark V90 if I ever use it. I gave up on that amp for personal reasons, but it never exhibited the issues you have described. Typical hum and noise with single coils is going to happen with any amp but it is not fizzy sounds.

Now I have a question or two to ask you. Did you buy the amp new? Is it a head with cabinet or is it a combo amp? If it is new, I would assume Mesa is using the STR441 tube in the power section. The preamp tubes will all be the same type. If the amp is used, it may be questionable what tubes are in the amp including the life of the power tubes. If it is a combo amp, it makes me think the speaker is questionable. I have burned out many of the MC90 speaker but that is just my luck. Usually the dust cap separates from the cone and it makes some nasty noise like the VC is toast. That will sound fizzy but on all channels regardless of voicing or power mode. It still does not rule out the speaker if a combo or the speaker cable if you have a head and type of cabinet choice and its associated impedance. Mesa amps prefer 8 ohm loads or 4 ohm loads. If you have two 8 ohm cabs, they should both be plugged into the 4 ohm jacks since the are in parallel. If you have two 16 ohm cabs, you can use the 8 ohm jacks, again the jacks will place the cabinets in parallel.

The power amp tubes seem to be fine. How did you determine this? Power tubes can make noise and some may be fizzy compared to others. If you do not have a tube tester then it is assumed they are ok but that is not possible to determine how they look when power is applied.

If the amp is new, I would assume they are the STR441 6L6GC tubes and the bias switch is set for 6L6. If the amp was second hand, what tubes are in the amp and is the bias switch set correctly for the type in use? It probably is since you did not mention power tube failure. Just note that the Mark V90 must be using all of the same type. Older Mark amps that were Simul-class could run a mixed set of 6L6 and EL34 including the Mark IVb. Not possible with the Mark V90 and have that to be sustainable.

If used amp: it was more common to have the Mesa STR440 tubes have been described as sounding Fizzy in some amps. Mostly with the MWDR or the JP2C. I never took notice to that with the Mark V90 though. Depends on the tube bias color as it is listed on a silver label around the tube base. For a Mark V90, the RED, YEL, or GRN are ok to use. If the amp has STR445 power tubes in it, well that is probably the problem. I tried those in the Mark V90 and it was a no-go. STR448 tubes did not sound good in that amp either.

Now for the Deep dive: What power mode(s) are you using? CH3 has 4 power modes when using 90W. At 45W you get the same combination.
  1. 90W full power and pentode mode
  2. 90W full power and triode mode.
  3. 90W Variac power and pentode mode
  4. 90W Variac power and triode mode.
For the 10W power, you only can select full power or variac power as the tubes will be runing in tirode. This holds true for all channels. Also it uses the Rectifier tube for the power supply.

CH1 and CH2 have only two for 90W, full power or variac power.
At 45W you get 4 power modes.
  1. 45W full power and silicon diode tracking
  2. 45W variac power and silicon diode tracking
  3. 45W full power and tube rectifier tracking
  4. 45W variac power and tube rectifier tracking.
Have you tried different power modes to see if the fizzy character changes?

Are you using the FX loop? If so, what is in the loop? To narrow things down with the amp, remove any FX in the loop so there is nothing plugged into the amp. Bypass on fx units may not be a true bypass so that can affect the sound quality some. If you are using the FX loop without anything plugged into the amp, try using the hard bypass mode. This will be loud so you should back down on the channel volume controls first.

You wrote: I also tried dialing back Gain, Treble and Presence. but as soon as I do that it sounds like a blanket over the amp, or i do not have enough gain. This will happen with any amp in general. Dialing back on the presence should not totally blanket the sound, backing off on the treble, depends on how much backing off and where is it set? Gain, That will also have some effect on the amount of distortion you get. I assume you feel the amp is too bright if you are resorting to that strategy? The Stratocaster can be on the thin side. As others suggested, boosting the guitar signal on the front end may help improve response. The amp should not sound fizzy regardless of the guitar and its pickups. It may be noisy though as that is the common trait for single coils to start with. Sometimes the quality of the guitar cable itself could be the culprit but doubt it as it would be that way more consistently than as you described.

How does the amp sound when nothing is plugged in? Does it make noises without any guitar signal? That usually is an indication if you have a bad preamp tube or power tube. Generally you may hear white noise or a slight hiss, perhaps a hum but that noise floor should disappear when signal is applied to the front end.

What model is your Stratocaster. Type of pickups in the guitar. Sometimes that can matter a great deal.

As soon as i switch into the Mark 1 mode or the Extreme mode, there is no fizzyness whatsoever.
This will take some time to decipher from the schematics. Something is up with that. I will post a follow up with my assessment on this issue.
 
Based on the characteristic of fizz, it goes away with the Mark I mode on CH2 and Extreme mode on CH3, that would suggest that there is a feed back change for both of those modes. The schematics I have do not have the details that control the relay RY-FB. I have seen the some of the missing content but did not include the matrix for the various modes.

Preamp tubes that get a voltage shift with channels are as follows: All of them. Go figure. CH1, CH2 and CH3 will set different voltage levels on the plates of the preamp tubes. Sometimes that can be all it takes to bring out the issue with the preamp tubes.

First one I would suspect is the Phase inverter tube V7. Since this tube is directly related to the negative feedback circuit (aka Presence), it will get a shift in character when using Extreme mode, I suspect the same occurs for the Mark I mode as well based on its audible characteristic. Fizzy tone goes away due to the drop in negative feedback signal to the phase inverter. There is a dramatic change in the Presence control when using the Extreme mode, None for CH2 but does not mean the source for the negative feed back circuit does not change with Mark I mode like it does with the Extreme mode as it uses the 4 ohm tap on the OT vs the 8 ohm tap for the other modes.

The next three culprits would be V1 and V3 as they are both used with all channels.

If I can remember the common issue with fizzy tone, it generally pointed to the phase inverter tube. It should be balanced and matched triode but not critical.

If you do not have any extra preamp tubes to mess with, I would try swapping V7 with V2 and see if that fixes anything with the fizz (CH1 and CH3) It is a 50/50 chance the tube in the phase inverter is not bad with both triodes, so it may affect CH2 or not when you swap them.

Another issue, check to see if the reverb cables are connected properly. The black one is more towards the front and the white one towards the back. If they are mixed up, that could make things sound terrible.

If this is a used amp, I would recommend preamp and power tube replacements to start with, this includes the 5U5GB tube. Just keep in mind the head version is more difficult to gain access to the preamp tubes especially V1. If it is a combo, that makes tube change much easier as you have more room to get your hands in there.

Just a note: the gap in the preamp tube pins faces the front on all preamp tubes except for V3 as that preamp tube faced the opposite direction. Getting the tube shields on and off is the hard part.

If you can get Mesa tubes, great. While you change the preamp tubes, you only need to remove the 4 power tubes, leave the rectifier tube in place so you do not mix it up with a power tube. I did that already, not a good thing to do. The Rectifier tube is the one closest to the power cord. There is a tube chart on the one side of the amp, sometimes it is hard to see. The manual also has that in the back for reference. Also, if you are going to reuse the power tubes, keep the outer pair together and the inner pair together. If they are Mesa tubes, look for the silver label it will be marked with a bias color RED, YEL, GRN, GRY, BLU. The first three colors listed are better for the Mark V90, GRY and BLU may have too much power tube saturation.
 
Sorry for the long post and questions, just trying to be helpful. Fizzy can mean many things, so without hearing what the amp is doing it makes it difficult to pinpoint the issue.
 
If this is your first tube amp, may as well let you know how to determine the power tubes.
If they are branded with the Mesa logo, the STR# will be printed on the glass just below the logo.
The types of 6L6GC tubes are as follows: STR440, STR441, STR443, STR445, and STR448. Since it is a Mark amp, the tubes face downward and the logo is upside-down. If you look at the black plastic base of the tube, there should be a label on it with 10 AC RED (YEL,GRN, GRY, BLU) The 5 abbreviated letters represent the bias color, red, yellow, green, grey and blue.

STR445.JPG


The rectifier tube does not have an STR# and does not have a bias color label either.

rECTIFIER TUBE.JPG



As for the preamp tubes, the type is usually above the mesa logo. 12AX7-A if it is hard to see in the picture. I pulled the images off of the Mesa website.

12ax7.JPG


For non-Mesa tubes, there will be no STR# unless it is specific for that brand. Most 12AX7 tubes including the ECC83 variety will have that on the glass and its brand or logo somewhere. Mesa does not make tubes, they buy them in bulk, and test them through a specific process. (the ink on the glass may be done by the manufacturer or it may be done by Mesa ). The label on the power tube is done after testing.
 
GREAT write-up, Bandit, GREAT write-up!

To the OP, I found my 2022-built JP2C to have a "tearing"-like sound in the top end, a kind of fizzyness I couldn't dial out without changing preamp tubes to ANOS (almost-new-old-stock), with 2 1950s RCA's in V1 and V2. The power tubes (from Mesa, STR445 I think, or 443) also by then had about 100 hours on them. This was playing through a fairly new vertical 2x12 recto cab. The fizziness finally went away. But about 6 months later, the V1 tube crapped the bed, so I put a Russian made EHX tube in there, with brand new STR448 power tubes on Bandit's recommendation. The fizziness is back... so it may be power tube related?
 
In respect to the OP on the new Mark V90. If this is a new amp that was manufactured within the last 4 years you still have a 5 year warranty that covers defects, I would send an email to Mesa customer service and ask how to fix the fizzy issue. Without hearing the fizzy sound, it is hard to relate if this is normal or something that should not be there. Some power tubes do have a fizzy characteristic to them and much the same can be said about preamp tubes. If the amp was made after 2020, the chances it has the original transformers that was used prior to the change in vendors is slim.

@Darkstar2 , my apology for recommending a fizzy power tube. I never considered the transformer change in manufacturers to have such an impact on tone characteristics. My JP2C (2016) is from the second or third run from 2016, it was shortly after they made a mod to the FX loop for the clean channel. I found the STR448 to sound great in my JP2C (2016). Not fizzy at all. Very much on par with the STR415 NOS tubes I bought direct from Mesa at about the same time I got the STR448 tubes. The STR448 has more chime on the clean channel compared to the STR415 and the gain channels there is a hint of airiness to the tone with the STR448 that has some musical appeal. the STR415 was just a bit more meaty sounding. I found the STR443 tubes lacked any power tube distortion, they were not fizzy and a bit too warm of a tube and got no where near the gain characteristics I was getting with the STR440 tubes with the same bias color. The lame ducks were the STR441, not a good fit for the JP2C (2016). I was impressed how they sounded in the Mark V90 (2012). May as well adopt adding the year the amp was made to the model-name. Perhaps that is TMI but now that there are differences that are not well documented, having the year reference may help.
 
No worries at all Bandit, I wanted to try a different power tube and your experimentation with them made me WANT to try various changes. The STR448's I got from Sweetwater (who couldn't send me color code BLU to save their lives...) are YELLOWS, so I know I can't have an exact apples-to-apples comparison. I figure the fizzyness goes away after about 100 hours of play time on the tubes. I'm probably at 30 hours so far on the 448's with the EHX Russian-made 12AX7 in V1. My next move is to get one of those new Ibanez 5-band parametric EQs that are coming in March and see if I can't dial out some of the fizz.
 
Just what the OP has dealing with, the Fizz should not be there. If this was the STR440 tube, I would have to say that is normal. If you had Blu bias color of the STR443 I doubt getting the same bias color in a different tube would be the same. When it comes to different tubes in the 6L6GC family, they do not sound the same. The STR445 is a wicked tube and it will also work well in the JP2C, actually they sounded much closer to the STR415 than the STR448. The one's that came in the Mark VII were greens, gave them a try in the JP and it was nice. Good match to the STR415.

I have some Yellows in the STR448, I will try them out in my JP and see how it works out. You got me curious if I would get the same effect. Reds, those will be lame. I have those too.
 
I'm always shooting for straight-up late 80s Metallica tones, or recent Heathen tones (Mark III). So that may impact what we're both describing to each other about tube characteristics and amp settings.
 
I am after more of a sinister tone. With that I can make adjustments with the GEQ or tone controls to suit many other sounds. More of the IIC+ heavy sound. I am not much for chugging but in that arena of sorts. Sort of on the modern scope vs the 80s hair band. Then again I do a lot of early stuff too like Led Zepplin, ACDC, Pink Floyd and the JP fits as it is quite flexible.
 
to the OP what did you get a head or a combo? if it's a head what are you using for a speaker cab?
 

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