Mk IIC+ and Mk IV ... same Lead circuid but sounds different

[justanotherboogieplayer]

Hi folks,

people say, that Mk IIC+ and Mk IV have the same circuid in the lead channel.
But those amps really sound different, how´s that possible.

I A/B ed the amps with a A/B Footswitch, that shortcuts the input of the not used amp, useing same kind of cabs with same kind of speakers in the same angle to listener, at low levels and high levels together with a rock band.

The amps sound different and ... the difference is not small.

You can get an eaqual colour of tone, but it is impossible to get the same richnes in overtones out of the MK IV as the IIC+ has. The dynamic range and the various range of attack of the C+ is also way better than the IV´s.
You can heare every kind of touching the guitar through the C+, while the IV is allways making a nice tone out of it, but not that different.

Does anybody have the same feeling or experiance?

People say, the circuid of the MK IVa is 100% identical to the C+ and the IVb is 98%. Why then is the sound so much different?
Is it the parts Mesa used in various years of production?

What about Studio and Quad Preamps?
Some say it´s the circuid of the IIC. Why not C+?
Early Quads and Studio Preamps (1987 ...) are closer to the IIC+ than MK IVs (1989 ...) are, ... are possibly the parts of those amps more the parts used on the C+?
Are the circuits truely the same, or are there differences?

Lots of questions, ... I know.
Is there anybody who is able to explane those things or have equal experiances, so please let me know.

 

[justanotherboogieplayer]

...forgot to say:

I used all arround equal preamp tubes and have 8 mached 6L6 tubes in the poweramps, so I think there realy are the same basic conditions when I compare the amps. (Did I forget something ?)
There are clearly noticeable differences in the amps ...
.... or am I hearing snowflocks falling down?

Please tell me about your experiances. Thanks.

 

[Marshall_Fascist]

join the rest of us lol.

I think the real tone of a IIc+ comes from the power section, not just the pre.

 

[justanotherboogieplayer]

yes you´re right, the poweramp is very important, too.
I owned a 60 W IIC+ and it had a little less dynamic range then my simulclass amps and a 100 W C+ had, that I was able to compare once.

But what about breath, overtones and attack ? Is it also formed in the poweramp so much?

A lot of people say, that the magic of the C+ lays in the pre.

... you bring me near to an idea ... thanks a lot for that.

I will go downstairs and cross over the amps and see, what happens.

Don´t know how, ... effects loop ... maybe the jack under the chassis, that´s splitting pre and power amp, but MK IV doesn´t have that ...

anyway I´ll go and try C+pre together with IV power and otherway arround.

Thanks.

 

[Boogiebabies]

People say, huh...


The MK IV does not have the same plate voltage or power supply filtering as the IIC+. It has a different OT and PT. You may get close, but a MK IV will probably not be an exact sonic duplication of the IIC+.

 

[justanotherboogieplayer]

Hi Marshall_Fascist,

you are right !!!

I didn´t think, the poweramp makes a big difference, ´cause it´s a simulclass in both amps, but it does!

I just tried it out. I used the effects send and returns to use the preamp of one amp and the poweramp of the other.
In one case you can switch easily on the footboard of the MK IV useing the loop on/off between the two poweramps.
Maybe the effects circuit has some influence on what I tried, too.
The slave out, as far as I know, includes the poweramp, so I didn´t try that and only the IIC+ has the jack between pre- and poweramp, so I only used the FX sends and returns to connect the amps.

The result was astonishing. There was a difference in loudness, which I adjusted (Poweramp of C+ sounds louder), but there also was a difference in dynamic possibillities, a little more attack and overtones in the C+ poweramp and it sounds a little more clear.
The difference was more than I expected.
But most of the difference between the two amps seems to be in the preamp. I can get an equal sustain and almost the same quality of overtones out of the IV, but therefore I have to give it more gain than the C+ needs. If I dial in equal kind of sustain etc., the IV sounds more compressed.
And it´s impossible to get the same dynamic range and breakout into overtones.

It´s interesting, what boogiebabies is stating... isn´t plate voltage or power supply filtering having an effect on both, preamp and poweramp ?

 

[Boogiebabies]

The IV has one less preamp fliter than the IIC+. The thing about plate voltage is that if it is there, the amp can draw it and maintain a certain level of attack. With the IV have 25-30 less nominally less tube current draw I find it to be smoother with the capability to sag just a bit. Witht he EQ engaged it could be a chugging demon as long as the lead presence is pushed in. This is also important when slaving. The R2 and lead have a different negative feedback circuit and dampen the power section slightly different from each other. The R2 pull has a 680pf cap and the lead has a 1000pf cap to the negative feedback loop. They both smooth out the power section.

Are you pulling the presence on the IV's R2 or lead channel.
It is much less compressed and more like the IIC.

 

[srf399]

So you;re saying that with the lead or R2 presence pulled out they are less compressed?

 

[Marshall_Fascist]

lol

glad I could help Boogie Player! Btw, I have a Mark III, so welcome to the mark family.

 

[Tuna141]

When I first got my Mark IV, I A/B'd it to my Mark IIC (non + version). Switching back and forth between the two amps, I tried to dial the IV to match the tone of the IIC. I could get in the same ballpark, but never really that close.

I had originally thought I'd sell the IIC if the IV could replicate it's tone. Well, I still have my IIC. The IIC's clean is much livelier and richer than my IV's. The lead channel of the IIC is much more touch sensitive, harmonically rich, has more singing sustain that the IV's.

Don't get me wrong, I love both amps. The IV offers tons of tone variation and offers great footswitching capabilities, which makes it an ideal live amp. But in the tone department, the IIC has it beat, IMO.

 

[Tuna141]

I can add some more input verses the IV vs the IIC's power section:

I use a Triaxis & Egnater IE-4 preamps in a rack for my live set-up. I've tried using both the Mark IV and the Mark IIC's power sections (via effects return jack) to power these preamps. I originally wanted to use the IV's power section due to the switching options available, but have found myself using the C's due to it's better tone. For some reason, the IV's power section sounds "boxier" and kind of flat when compared to the IIC's.

Both amps have EV speakers. To be fair, I never swapped preamp or power amp tubes (both 6l6's) between the amps, so the tubes may be contriobuting to some of the difference.

 

[Boogiebabies]

So you;re saying that with the lead or R2 presence pulled out they are less compressed?

Less.



I have to disagree on the MK IV clean. Mine has more bounce than
and NBA game and is more controllable than the IIC due to the master
controls. Now, I am not saying that the IIC clean is not better than the IV, but a bit easier to balance.

 

[justanotherboogieplayer]

Hello Tuna 141,
I totally agree. You absolutely found the words to describe it.

Thank you very much, Boogiebabies, you know a lot about Boogies.
I tried out the R2 and Lead Presence pulled and the IV didn´t sound that much compressed any more, but stil more than the C+.

It is amazing to see (hear) that the poweramps have so much influence on the total result and that there is a noticeable difference between IV and C+, even if it is Simul Class in both amps.

I bought 8 mached 6L6 Tubes, to have the same basic conditions when I compare Poweramps. What I found out, is exactly the same as Tuna is describing.

It is so nice (and cheaper) to take a IV to live performances, but when I do, I´m missing something and the audience, even non-guitar-players, they notice the difference. Maybe I´m playing different, when I have the C+ with me.

Poweramp .... I know alot more about it, since all you nice guys helped me, but still there is the Preamp - Difference.

Does anybody know more about Studio Pre or Quad ?

Why is the chanel I in a Quad build like a C, not like a C+ ?
Is it really the same ?
How about the Studio Pre ?

 

[4nkam]

Does anybody know more about Studio Pre or Quad ?

Why is the chanel I in a Quad build like a C, not like a C+ ?
Is it really the same ?
How about the Studio Pre ?

I'm always curious to learn more about the Studio and Quad

MJ

 

[Marshall_Fascist]

Does anybody know more about Studio Pre or Quad ?

Why is the chanel I in a Quad build like a C, not like a C+ ?
Is it really the same ?
How about the Studio Pre ?

Same Here!!!!


Like, why is the top part of a quad a IIc? and not a +? And why is the bottom part, a black dot III? Why not a blue or green or red or even purple?

 

[Tuna141]

Boogiebabies,

"I have to disagree on the MK IV clean. Mine has more bounce than
and NBA game..."

I'm still not real happy with my IV's clean. I'm looking for more of that jangly Fender/Vox type clean, that I just can't seem to dial in - it always seems flat and boxy/midrangy to me. If I up the treble & presence, it gets kind of ice-picky and harsh. I was able to liven it up some by dropping in an EI Gold preamp tube, but it still not to where I'd prefer it.

Would you mind sharing your settings? Thanks.

 

[justanotherboogieplayer]

.... the more I compare, the more I notice a difference.

Useing the clean channel, the difference is even bigger, I feel.
You have to use R1 and R2 of the IV to get the whole bandwidth of the IIC+´s clean channel, while R2, especially whith "fat" is able to go into the C+´s lead area.

I mostly play a R9 Les Paul with Dommenget PickUps, which have 4 wires. With push-pull I can change from common HB to parrallel wired coils, kind of inbetween sounds of a strat, but in one PickUp.
So this guitar has a really wide range of output I can switch between and dial in with the volume pot.
If I use those possibillities, what I´m doing more than switching channels, I allways find the C+ much more sensitive than the IV. That is noticeable in varriation of loudness of the note and also in character, clean - chrunchy, soft - agressive, whispering - crying, etc. ... changing just by the way you hit the string and allmost clean to fully cranked, useing vol. pot. and coil switching, too.
I can´t emagine any amp being able to compare with the C+ in this.

MK IV has more separated areas for each channel. You can get really clean to more-than-you-need-distortion, but therefor you have to switch between channels. Then you can get the edges of every area.

But it lacks a bit of touch-sensivity, when you compare to the C+. Here you can change the character of tone from note to note, without the need of switching.
This is really noticeable, if you use clean channel only, too.

Settings:
MK C+ :
Vol 1 6-8, (´cause lead is useing Vol1, too.)
Trb. ~ 7,
Mid. 4-7,
Bass allways lower than 3,
Master. ~2
Ld-Gain 4-7.
Ld-Mast. ~ 4
EQ ~V,
Pres. 5-7,
Rev. 7-8 (no other effects any more, exept a Maxon AD900 in the FX)
Pull Deep,
Vol 1 - Bright.

MK IV
... ? ... don´t really know. I´m still twistin´ and switchin´.
... didn´t find anything like the "Pull Deep" yet.
... some extreem settings are interesting, like R1 or R2 Gain at 10, +"Fat",
or extreme EQ settings.
... honestly ... I don´t know jet.
It´s allways a good tone, but I didn´t find, what I like at the II C+, though.

 

[Boogie Woogie]

Hi to all,

I am also an owner of a Mark IV, I have the wide body combo version to which I added an Avatar 2x12 cabinet (V30 with V12h30).

I have been also on the quest of having the MKIIC+ sound out of my amp. I opened it yesterday and following the schematics found on the net, I saw that there was small differences in the circuit. I will identify all the differences and post them soon.

What I discuvered is that the amp must be in full power mode to have enough plate voltage on the tubes to sound good. On full power, with EL34 in the outside sockets the voltage measured on pin 5 was 46.5V and in the inner sockets 50V. Now I don't know if these are correct or they should be higher? Any one could help on this?

I also was wondering what are the modifications requires to match the circuitry of the MKIIC+. I am an electrical engineer and have done a lot of modifications in tube amps, but I always had the schematics. In this case, the ones I found on the Internet were incomplete. I would really appreciate it if Boogie Babies you could send me these schematics.

Thanks a lot for all the help!
Note: my email is [email protected]
Keep rockin!