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Likewise, you are probably aware that the "Gain Boost" pull switch is not really the original gain boost circuit that lifted the drain of the tone stack via a foot switch or pull knob. It is a switch button that changes the filter shelf at the back end of the amp, later relabeled as such on the...

the added pot on the back is a post fx loop master. as simple as that. the loop mod then will add more gain, but there no change in the front panel knobs meaning.

Nah man, they removed it simply because there was not enough space for it on the faceplate. And imho this is a big issue since you cannot turn everything down without messing with the channels' level Mark iv had a global master volume and each channel had a channel volume. solo volume means to...

I will. FYI red channel has no feedback on all rectos (it's the trademark) thus this reduces the variables quite a bit hopefully

@bjosephs thanks for your input! By comparing roadking II schems vs rev F, as far as the ch3 and ch4 are concerned, I cannot find any reason why the RKII has mids so much prominent. Must be something not shown in the diagrams as you said.

So let me turn it back around once more since you likely have more amp experience- wouldn't the tail end be more sensitive to changes upstream in the tone stack including the existence or lack of a ghost circuit? There is a slight difference on the 1st part treble cap on the Rev F schematic. Not...

Why implemented? I wouldn't know but smoothing comes to mind when channel switching. It just doesn't seem substantial enough to make a difference to my unlearned head. If all the pots were providing minimal impedance in the RC network of the non-selected channel and relative higher impedance in...

Hi, with rev F and rev G I mean the first dual rectifier solo series, check www.rectifierguide.com Rev F has Mark III transfomers true and it might have different PI coupling values, and it is less muddy than the rev G, IMHO due to a different bass frequency handling in the first RC network...

Hi guys, so I've always wondered why the first dual rectifier series (up to Rev G) was more mid-scooped than all of the later rectifiers, including the tremoverb, which is based on a rev G. I've started to download and compare all of the available schematics, and started looking specifically in...

MKIV Rev A lead channel Vs MKIV Rev B Lead channel

How common are the 6-tubers? I would dare to say "unicorn-like" :) The tone stack is pre distortion, it is plate fed and it has a recovery stage afterward, so I don't really understand what's the point of having a cathode follower here.

@electric mayhem you can find the best unofficial schematic here https://boogieforum.com/threads/mark-iic-schematic-correct.74680/ But I think you already knew this, so I write it here just in case. What preamp PCB revision is this? (RP11A, RP11, RP11 etc..) Does it have any additional knob...

Mark iib went through different iterations, from RP9A pre amp board which is more loose on the bass side to the RP9C which is tighter (gain pull is also changed to pull deep), similar to the IIC. I have a vintagey RP9A SRG loop modded by MB and I Love it. The loop is now usable and the amp has...

to those that say that R2 is very different between rev A and rev B. I've checked the schematics available online and the only prea amp differences I could find are in the lead circuit, where the rev A is more similar to the IIC+. I did not find any difference in the circuit used by the R2.

Thanks!!! You are a hero!

You should search this forum, there should be circuit changes in both schematics and layout formats that show you the required changes based on the pcb revision board. A IIC pcb reworked becomes de facto a iic+: loop improved, pre and power amp are set to iic+ specs. Then there is the iib loop...

Hi guys, does anybody have a copy of this PDF? It's not online anymore. thanks

It depends... are you using the lead channel or the clean channel only? On the mark II B/C the tone stack is plate fed and put before the VOL1 gain. Then the signal is sent to the lead channel (lead drive). On the mark I, the tone stack is plate fed, but put after the VOL2 gain, and VOL1 acts...

Nice! 100w/60w is class a/b only and hence it is not simulcass. (Class a/b and class a in parallel). If you ever want to sell, let me know! Ciao

Of course there are. 60w, 100w or 75w (simulclass)? Graphic eq or not? Export power transformer or US domestic