MARK IV SETTINGS AND LEAD MODE EXPLANATION

[TheTrooper]

Hi there! I just bought a Mark IV Rackmount Head. It's a 110v version, but since i live in EU i use a converter. I have some questions:
On Lead mode, the sound is.....CLEAN. I mean, no overdrive, similar to R1. I don't understand why; i know each knob is a different gain stage, but even with the Lead Gain on 8 with FAT pulled and Lead Drive on 7-8, i don't have distortion, while i have distortion on R2. It's me not understanding something, or a problem of the amplifier? Now another question: How to tame the volume? It's pretty loud for me (for anybody who still wants to hear eheh). Any advices? Maybe some setting to try out?

 

[bgh]

Are you getting any reverb at all? Reverb and lead share preamp tubes V3 and V4. If your reverb is not working, perhaps one of them is bad and is letting only a clean signal through. (But, thinking it through, this may not be the issue).

Does the tone stack work for the lead channel? Does it have any impact on the tone? Do the lead gain and drive each impact the tone? Do they impact the volume at all? Does the channel volume on the lead channel work?

If you bought this used, is there any possibility that (one of) the previous owners made a mod to the amp - and tried to clone channel 1 into channel 3?

A few final things to test: Does pulling the presence knob for the lead channel do anything at all? Does adjustment of the presence dial impact the tone at all? (I know these are associated with the power section of the amp).

Off the cuff, these are the external things that I would try first. I don't know enough about the internal workings of amps to be able to give you any reliable help.

I sure hope you find out what it is. The lead channel on the Mark IV is an excellent sound.

Thanks for reading.
Hope my feeble attempt is helpful to you.

 

[TheTrooper]

Wow, thanks for the reply and for all the information. I should clarify that is not CLEAN and stop, there is a little bit of distortion, but with gain on 8 with FAT pulled and Lead Drive on 7 it's not a "Lead" (like a Petrucci Lead) it's just a little bit of distortion, and we all know what this monster is capable of with Gain on 8.......
Ok, let's start with question #1:
The reverb maxed on 10 is not really a reverb (or what i refer to a reverb). There is no "depth" or "delay", but a different high frequence (i don't know how to refer to) and a nice amount of hiss or hum (more than when it's off).

#2:

Tone stack: I don't know what you actually mean for "tone stack", but yes, turning the gain and lead drive up there is a change in sound and volume. The Lead master (or volume works).

#3

It's not modded; even if i know nothing about amps, i know that wasn't modded. It's just the Lead that souns strange...

#4

Ok, the presence control.......it doesn't impact the sound really in a big way, maybe has something to do with my problem.

I'm currently using it with a Step down transformer, 220v that gives me 110v. The transformer support 200w (and i don't know what the hell this means), should i use something different? (i don't think, probably if the tranfsormer wasn't working, i would have blown the amp yet)

The amp arrived to my door with the 6L6 not in it, but i put them back.....there is a particular order? Maybe i put them wrong?
I saw a preamp tube (maybe the reverb tube?) that has a white something on the top.....is it normal?
Now that i'm writing i heard again a noise that i forgot: when i turn the amp off, i hear like a little "crackling" noise 2-3 times every some minutes (like a click of some sort). It has something to do with the tubes?
Yeah, definetly i will have the amp check out by somebody in my area.
Thanks again for all the help.
Just a little question.....should i run this monster at high volumes? It's hard to use in my bedroom, but i never had problems of volume with other preamps (modeling or with tubes) and power amps.
I don't have any footswith, so i run thru the different channels with the rotary swith in the back. Does this affect the functions in any way?

 

[ryjan]

Tone stack = Bass, treble, etc

99.9999% chance of a bad preamp tube. Replace them and enjoy your new amp.

 

[TheTrooper]

Tone stack = Bass, treble, etc

99.9999% chance of a bad preamp tube. Replace them and enjoy your new amp.

Oh, ok. Yeah, Bass, Mid and Treble affect the tone (Mid and Bass less than Treble, but it's how a Boogie works, i read the manual everyday, i find it relaxing )

Well i hope that the problem are only the preamp tubes.....any advices? Brand or whatever? Should i replace the reverb one?

 

[bgh]

I my original post, I thought you were getting a clean sound through the lead channel. Thus, the range of questions (and the question about the amp being modded).

If you are getting some distortion, and your reverb is having issues, I go back to what I was thinking earlier - either V3 or V4 is bad. Replace them one at a time with a new preamp tube and you will probably get the issue fixed.

PS: To answer your other question, on the Mark IV, the reverb is spread over two preamp tubes - V3 and V4.

PS2: (Other than being a horrible computer) - I run TADs in V3 and V4 of mine.

 

[TheTrooper]

I kinda want to replace all of them, not only one. I might buy from Eurotubes, they have pretty decent prices. Let's say i want to replace the 6L6s too: i know the BIAS can't be adjusted, but i can put any type of tubes? Even if not Mesa's? If i put JJ 6L6 do i have to pick the ones with my amp bias or whatever BIAS they have it's good?

 

[bgh]

Even if you replace all of them, I would replace them one at a time (starting with v3 and v4). Otherwise, you will not know which one of your existing preamp tubes are bad. Toss the bad ones and keep the good ones as emergency spares.

There is a sticky-thread at TGP that lists a bunch of online tube retailers. Lot's of good experiences with Doug's Tubes and Eurotubes. Tell them you want either a quad or 2 pairs of power tubes for a Mark IV and they will pick out some that are in the correct bias range.

http://www.thegearpage.net/board/showthread.php?t=1197164

Hope this helps!

PS: I run 6L6s in the inner pair on mine, and EL34s on the outer pair. Sounds very nice. Plus, when running in "class A", I get an EL34-only sound. It's pretty cool.

 

[dodger916]

I kinda want to replace all of them, not only one. I might buy from Eurotubes, they have pretty decent prices. Let's say i want to replace the 6L6s too: i know the BIAS can't be adjusted, but i can put any type of tubes? Even if not Mesa's? If i put JJ 6L6 do i have to pick the ones with my amp bias or whatever BIAS they have it's good?

You can use any tubes, PROVIDED the tubes draw the correct current when idling at your particular amp's plate voltage. In an adjustable bias amp, you get tubes that match each other for idle current draw, and then adjust the bias so that they idle at ~ 70% of maximum plate dissipation (MPD). In Mesas, because they don't have an adjustable bias (aside from swapping resistors), you must get tubes that naturally idle within Mesa specs at your amp's plate voltage. And here's the rub: many on-line dealers will grade tubes at a specified plate voltage, which may not align with your amp's plate voltage. Reputable, knowledgeable dealers will know this and supply tubes that idle within the Mesa range when run at your amp's plate voltages. Mesa pre-grades their tubes to ensure they are matched and fall within Mesa specs.

Eurotubes is a knowledgeable dealer. I've bought power tubes from them in the past, and they understand Mesa amps and the grading process. You can also use tubes from Groove Tubes that fall within their Distortion Rating between 4 and 6.

Preamp tubes won't matter for a Mark IV, but some Mesa amps that have a "cathode follower" preamp tube slot that will require a more sturdy tube in that slot(s). Chinese tubes are good in cathode followers; Russian tubes no so good. Hope I didn't completely confuse you!

 

[TheTrooper]

I kinda want to replace all of them, not only one. I might buy from Eurotubes, they have pretty decent prices. Let's say i want to replace the 6L6s too: i know the BIAS can't be adjusted, but i can put any type of tubes? Even if not Mesa's? If i put JJ 6L6 do i have to pick the ones with my amp bias or whatever BIAS they have it's good?

You can use any tubes, PROVIDED the tubes draw the correct current when idling at your particular amp's plate voltage. In an adjustable bias amp, you get tubes that match each other for idle current draw, and then adjust the bias so that they idle at ~ 70% of maximum plate dissipation (MPD). In Mesas, because they don't have an adjustable bias (aside from swapping resistors), you must get tubes that naturally idle within Mesa specs at your amp's plate voltage. And here's the rub: many on-line dealers will grade tubes at a specified plate voltage, which may not align with your amp's plate voltage. Reputable, knowledgeable dealers will know this and supply tubes that idle within the Mesa range when run at your amp's plate voltages. Mesa pre-grades their tubes to ensure they are matched and fall within Mesa specs.

Eurotubes is a knowledgeable dealer. I've bought power tubes from them in the past, and they understand Mesa amps and the grading process. You can also use tubes from Groove Tubes that fall within their Distortion Rating between 4 and 6.

Preamp tubes won't matter for a Mark IV, but some Mesa amps that have a "cathode follower" preamp tube slot that will require a more sturdy tube in that slot(s). Chinese tubes are good in cathode followers; Russian tubes no so good.

Hope I didn't completely confuse you!

Sorry, but you did! HAHAHAH .
I understand nothing about tubes and stuff like that, but from what i have read from you, that means that i should know the voltages of my amp, so i need somebody that can tell me that, right? I have to take the amp to a tech in my near area....What's the name of the tool that reads the voltages? (i can't remember)

 

[bgh]

I kinda want to replace all of them, not only one. I might buy from Eurotubes, they have pretty decent prices. Let's say i want to replace the 6L6s too: i know the BIAS can't be adjusted, but i can put any type of tubes? Even if not Mesa's? If i put JJ 6L6 do i have to pick the ones with my amp bias or whatever BIAS they have it's good?

You can use any tubes, PROVIDED the tubes draw the correct current when idling at your particular amp's plate voltage. In an adjustable bias amp, you get tubes that match each other for idle current draw, and then adjust the bias so that they idle at ~ 70% of maximum plate dissipation (MPD). In Mesas, because they don't have an adjustable bias (aside from swapping resistors), you must get tubes that naturally idle within Mesa specs at your amp's plate voltage. And here's the rub: many on-line dealers will grade tubes at a specified plate voltage, which may not align with your amp's plate voltage. Reputable, knowledgeable dealers will know this and supply tubes that idle within the Mesa range when run at your amp's plate voltages. Mesa pre-grades their tubes to ensure they are matched and fall within Mesa specs.

Eurotubes is a knowledgeable dealer. I've bought power tubes from them in the past, and they understand Mesa amps and the grading process. You can also use tubes from Groove Tubes that fall within their Distortion Rating between 4 and 6.

Preamp tubes won't matter for a Mark IV, but some Mesa amps that have a "cathode follower" preamp tube slot that will require a more sturdy tube in that slot(s). Chinese tubes are good in cathode followers; Russian tubes no so good.

Hope I didn't completely confuse you!

Sorry, but you did! HAHAHAH .
I understand nothing about tubes and stuff like that, but from what i have read from you, that means that i should know the voltages of my amp, so i need somebody that can tell me that, right? I have to take the amp to a tech in my near area....What's the name of the tool that reads the voltages? (i can't remember)

All you need to know is which Mesa amp you have - the tube dealer will be able to tell you which tubes can operate best in the ranges for that Mesa amp. Eurotubes is particularly good at this (the tubes in my Mark IV came from them).

Now, if you decide to buy and install tubes "off the shelf", then you will need to bias the amp to match the tubes you put it. But, Mesa amps do not have an adjustable bias.

The easiest thing to do is to buy tubes that match the known voltages of Mesa amps. The tube dealer should be able to help you.

 

[Authorized Boogie]

I saw a preamp tube (maybe the reverb tube?) that has a white something on the top.....is it normal?

A white tube indicates a loss of vacuum = failed tube. You need to do some preamp tube troubleshooting and you should be fine.

 

[TheTrooper]

I kinda want to replace all of them, not only one. I might buy from Eurotubes, they have pretty decent prices. Let's say i want to replace the 6L6s too: i know the BIAS can't be adjusted, but i can put any type of tubes? Even if not Mesa's? If i put JJ 6L6 do i have to pick the ones with my amp bias or whatever BIAS they have it's good?

You can use any tubes, PROVIDED the tubes draw the correct current when idling at your particular amp's plate voltage. In an adjustable bias amp, you get tubes that match each other for idle current draw, and then adjust the bias so that they idle at ~ 70% of maximum plate dissipation (MPD). In Mesas, because they don't have an adjustable bias (aside from swapping resistors), you must get tubes that naturally idle within Mesa specs at your amp's plate voltage. And here's the rub: many on-line dealers will grade tubes at a specified plate voltage, which may not align with your amp's plate voltage. Reputable, knowledgeable dealers will know this and supply tubes that idle within the Mesa range when run at your amp's plate voltages. Mesa pre-grades their tubes to ensure they are matched and fall within Mesa specs.

Eurotubes is a knowledgeable dealer. I've bought power tubes from them in the past, and they understand Mesa amps and the grading process. You can also use tubes from Groove Tubes that fall within their Distortion Rating between 4 and 6.

Preamp tubes won't matter for a Mark IV, but some Mesa amps that have a "cathode follower" preamp tube slot that will require a more sturdy tube in that slot(s). Chinese tubes are good in cathode followers; Russian tubes no so good.

Hope I didn't completely confuse you!

Sorry, but you did! HAHAHAH .
I understand nothing about tubes and stuff like that, but from what i have read from you, that means that i should know the voltages of my amp, so i need somebody that can tell me that, right? I have to take the amp to a tech in my near area....What's the name of the tool that reads the voltages? (i can't remember)

All you need to know is which Mesa amp you have - the tube dealer will be able to tell you which tubes can operate best in the ranges for that Mesa amp. Eurotubes is particularly good at this (the tubes in my Mark IV came from them).

Now, if you decide to buy and install tubes "off the shelf", then you will need to bias the amp to match the tubes you put it. But, Mesa amps do not have an adjustable bias.

The easiest thing to do is to buy tubes that match the known voltages of Mesa amps. The tube dealer should be able to help you.

I don't have to check the voltages with a particular tool? If i tell Eurotubes that i have a Mark IV rackmout that runs at 117v (110v or whatever) they can privide me a set of preamp a power tubes so easily?

 

[ryjan]

I don't have to check the voltages with a particular tool? If i tell Eurotubes that i have a Mark IV rackmout that runs at 117v (110v or whatever) they can privide me a set of preamp a power tubes so easily?

Yup.

My advice is to simply order a complete set from Mesa. Their tubes sound great and are guaranteed to work in the correct range. An definitely, buy two 6L6's and two EL34's. They sound amazing in the Mark IV.

 

[TheTrooper]

I don't have to check the voltages with a particular tool? If i tell Eurotubes that i have a Mark IV rackmout that runs at 117v (110v or whatever) they can privide me a set of preamp a power tubes so easily?

Yup.

My advice is to simply order a complete set from Mesa. Their tubes sound great and are guaranteed to work in the correct range. An definitely, buy two 6L6's and two EL34's. They sound amazing in the Mark IV.

Well, i can't thank you guys enough for the help you are giving me. Ok, i will definetly try 6L6's and El34's.
Thank you all again!

 

[ryjan]

No problem. The Mark IV is still in my top 3 best all time amp category. I was stupid and sold mine a few years ago but I will get another some day.

 

[TheTrooper]

Just another silly question: How do i date the amp? The serial number is 012550

 

[Authorized Boogie]

Just another silly question: How do i date the amp? The serial number is 012550

That amp left here 10/05/2006

Thanks!

 

[TheTrooper]

Just another silly question: How do i date the amp? The serial number is 012550

That amp left here 10/05/2006

Thanks!

Thank you very much!

 

[dodger916]

Just another silly question: How do i date the amp? The serial number is 012550

With an amp that age, I'd start with dinner and a movie. :wink: