3 Channel Dual Settings

[afu]

For sheets and giggles, I swapped modes on Channels 2 and 3. I read in another post that my channel 2 is most like the second channel of the 2 channel rectos and I wanted to try that out. I put Channel 2 on Modern and Channel 3 on Raw. I use Modern for AIC, Metallica, Soundgarden, and other "heavier" stuff. Raw is for Zeppelin, Monster Magnet, AC/DC and stuff like that.

The weird thing is the gain and volume settings are different between the channels. I don't use loads of gain, but the difference is striking. Modern Channel 3 would have volume on 10:30 and gain on 12. When I put this on Channel 2, I had to drop the gain to 10 and raise the volume to 11 or more to get an approximate sound.

Same thing with Raw. On Channel 2, I would have the volume and gain in the general area of noon. On Channel 3, I have the volume on 12 and the gain at 9. I did clean it up a bit more than usual, but getting it to the normal sound is at about 10:30. I know the presence control is different on 3, but it doesn't seem to have a lot of taper until it's almost maxed out and then it's easy to make it really harsh. Switching to Vintage on Channel 3 gives more use of the presence, but I have to have the gain knob just turned on just low enough to start making sound to be in the ballpark of my Raw setting.

The other weird thing is that the overall channel characteristics have changed. The normally dark 2 is brighter and the normally bright 3 is darker. The modes aren't as dark or bright as when they're in the other channels, but it's striking. I know the channels are optimized for 2 to be Vintage and 3 to be Modern, but it's weird how a change in the gain structure made such a difference.

 

[ryjan]

For a more convincing Metallica tone that has all the fury but added tightness sans boost try Vintage mode in channel 2 (3 for the Roadster). I've found through my extensive (and often unhealthy) fanboi tone obsession to be where the Jaymz tone lives. With the right settings, guitar, and playing you get a great Load/Reload/Garage Inc tone with all the Recto anger and a hint of Mark Series bite and sweetness.
Since dialing this sound in I have not really had a use for Modern mode except when I'm jamming alone and want that fun "SOOPER SCOOP" metal tone that disappears in a mix.

 

[afu]

After seeing Metallica live, it struck me how deep and clear James' sound is. For awhile, in Channel 3 on Modern I used the following to get a tone that sounds really good for Creeping Death, Fight Fire With Fire, or And Justice For All:

P: 12:30
B: 12
M: 10
T: 1
V: 9
G: 11:30 - 12:30

I notice he doesn't really crank the gain these days, but Kirk seems to. I know the Deizel is making a lot of his sound, but I'm not shelling out that much for an amp. And his secret mods on the Triaxis make owning one to get his sound pointless. My Dual will have to do.

Lately, I've been giving a lot of love to Vintage and Raw. After much twiddling, the gain modes overlap quite a bit and getting my Modern distortion on Vintage is really freakin' easy and has less of the piercing highs that have to dialed back. I've started to dump all the frequencies over 9 kHz just to have a clear, yet finely distorted sound. I can even kind of ape a Marshall tone by cutting the bass to 9 or 10, mids around 1, and treble around 4.

Anyway......

 

[afu]

And speaking of Soundgarden: http://youtu.be/uEl7u9Z3lK0

They show Kim's Tremoverb settings around the 28 minute mark; front and back.

 

[ryjan]

Those are some good settings. Very neutral and balanced. Keeping the gain around (or under) noon is the secret to keeping a Recto tight. Any more gain and it gets mushy and buzzy.
When I first got my Roadster I set channel 4 to Modern and channel 1 to clean and kind of blew off the rest. I ran through the other modes in all 4 channels of course but I never gave them much time because I assumed I'd mainly live in the modern mode. After a while I started getting a little bored with it so I began looking in craigslist and the forum classifieds for a Mark IV or something a little more...well...I guess something a little less punishing. :lol:
The Modern mode is fun and for certain genres it's almost a custom fit but for fast or technical thrash style riffs the extended bottom, stiff feel, and scoopy tone can be a bit of a turn off. I thought I'd go back to the Mark series amps which I love but always struggled with.
After messing around with the vintage mode in channel 3 a few months back I've changed my mind. It has all the qualities I loved in my old Mark IV but none of the finicky, schizo crap that they are known for. Plus the Mark IV has two channels (Rhythm 2 doesn't exist in my world) where my Roadster has 4 very useable channels and several other great features that I actually use.

The funny thing about using a Recto to get the Metallica sound is I found that Modern works best for their old MOP and AJFA sounds with the bass and mid backed off and the presence and treble a bit higher and for their modern and live tone channel 3 (2 on your 3 channel Recto) Vintage with your settings nails it. :lol:

 

[Jorn218]

afu and Ryjan would you please expand on what you guys are talking about a bit more with some setting examples so I can wrap my head around this some more? This is a very interesting bit of information and I just want to make sure I am understanding it properly.

 

[afu]

I'm not sure what you want expanded. Can you ask for specific details?

 

[ryjan]

I wasn't aware we were being vague. :lol:
I was going on and on of the virtues of channel 3 vs channel 4 on my Roadster. This equates to the virtues of channel 2 in a 3 channel Dual or Triple Recto. Our member Silverwulf pointed out in another thread that this channel is more akin to what one would find on the old 2 channel heads which is what I believe spurred this discussion.
What setting examples are you looking for? What kinds of music do you play?

 

[Jorn218]

Sorry guys, I might have made myself a tad confused. I was reading what yall wrote, but interpreting it as if one would use say on a 3ch rec, ch.2 vintage, you get a gain structure that is as mean as ch.3 modern, but not along with the tonal qualities that make ch.3 annoying to listen to after a while.
I am asking because I have not ventured beyond ch.2&3 modern, and ch.1 both clean and pushed. This I the first thread where I have read of ch.2&3 vintage and raw actually being able to be used to mimic other channels modes to make them useful. If I can utilize knowledge you guys are passing along, I could apply it to my own applications.

Ryjan, you werent being vague. I just wasnt grasping what you guys.were talking about. You asked what type of music I play. I play blackened death metal exclusively through my Mesa rig. The one thing I never liked about my D.R. is ch.3 modern playing this style of music. Ch. 3 Is too my ears, way too inorganic. It is fine for thrash maybe, but it does not have that liquid boogie vibe to it. I am chasing that liquid mark 1 vibe with the D.R. using more gain and tonal shape of the Rectifier amps. I know it is there hidden somewhere, hiding behind ch.3 grunt grunt grunt chugga chugga chugga dryness. Youguys were talking about unlocked secrets of vintage and raw modes so my ears perked up.

If you arent folowing me maybe a visual reference may help.
waynebarlowe.wordpress.com/artwork/hell
How Barlowe is capturing the organicness of his interpretation of The Pit, I am after a tonal organicness that gives a similar feel.

 

[ryjan]

Forget the rest of the amp for a while and just mess with your channel 2 in vintage mode. Full power and diode rectification. Start with everything around noon and work from there.

 

[afu]

The distortion available as you turn the gain knob overlaps between modes, with Vintage being able to get the upper distortion of Raw and the lower-to-mid settings of Modern. The feel is a little different, but not by much. Turning the gain above 1 or 2 o'clock on any of the modes begins to get mushy so if you want a little more distortion or a clearer distortion from your Raw mode, switching to Vintage and setting the gain low will get you the same sort of sound. Alternately, if you play on Modern with the gain at or below 12, you can get about the same sound on Vintage mode, but it may be less defined.

Modern mode has a different feel. Part of it is the taper and design of the presence in channel 3, but another aspect is (if memory serves me) a bypass capacitor on the cathode(s) in the preamp. This attenuates some of the lower frequencies and produces that tighter bass response. Attenuating the lows also shifts the middle frequency up a little and gives the mode a brighter feel. In combination with the presence circuit in Channel 3, you get a very percussive, yet deep sound.

By dialing in a similar distortion in Vintage that you can get in Modern, you will have a fatter low end and feel, but slightly less definition. Dialing in the sound on Channel 2 of a DR will give you the "proper" presence control from the negative feedback circuit, which is less percussive. YMMV, but it's just a different way to get a similar sound.

My original post was surprise at how the Modern mode changes channel 2. After thinking about it for awhile, I was able to think about the way the circuit changes and what that would do, but it's still really strange in practice.

 

[Jorn218]

Alright I am getting it. I will need to apply it to practical application now.

For lack of better terms the gain structures could be visually represented in a similar fashion to this

Raw: 1 2 3 4 5 6 7 8
Vintage: 7 8 9 10 11 12 13 14 15 16
Modern: 15 16 17 18 19 20 21 22 23 24

While not exact, it simplifies what you guys are saying. breaking up each mode into a range of 8 digits(while each alone would be 1-10 on its own scale) the modes overlap slightly at each end.

Re reading the manual about the Gain knob when discussing it alone, I can really see where the channel cloning on the old Rectifiers would really become useful. You could set one as your rhythm setting and bump the gain up a bit to add more compression for leads while retaining the exact tonal settings on the other channel.

Now reading further when applying the tone controls, it seems that great detail is discussed with trebles and mids while bass seems to be almost an afterthought. Quote, "However, the actual frequencies and style of lows it mixes in changes from channel to channel". A little more detail here from Mesa as they did for mids and treble would have been nice.

One last question. Do either of you know what the frequency range each channel is tailored for in respects to each mode? IOW the upper and lower extremes as well as the mid peaks.

NOTE: I did not know that the 2 channel heads did not have the same modes as the three channel heads.

 

[ryjan]

That's a good analogy for how the gain structure overlaps in the modes.
The tone controls are not like that of a parametric EQ. They don't really boost or cut a set frequency but they control the amount of signal passing through in that frequency range.
I'm not an electrical engineer so I can't really explain what's going on from that perspective but I did have this explained to me by someone who works on amps once. He said to imagine a water pipe and each tone control was like valves diverting the water to different places. The first valve is the most important, right? Because this valve decides how much water will continue to flow to the next valves depending on how wide you open it. This would be the treble control. It's first in line and like the water in the pipe your amp only has so much signal to ultimately send to the power amp. Crank it all the way up and there will only be a trickle left for the rest. Keep it balanced and you'll have a more even amount of signal to distribute to the other tone controls.
As for what frequencies are manipulated in each tone control we'll all have to wait until someone more knowledgeable than me comes along to help.

 

[afu]

The reason bass is considered least is because it has the least effect on the circuit. In TMB EQ circuits, bass is surrounded by treble and mids; the treble comes first, bass comes next, and the mids go to ground. That's why the treble has the most influence over the circuit; it gets the whole signal and spits it out after filtering the lows. The mids not only affect your middle ranges, but also determine the amount of low frequencies you hear. Those lows will become more prominent as you turn the mids down.

The tone controls in the Rectos come after the preamp stage. Tone controls require an additional amplification stage to recoup lost volume. Rectos do this with the FX loop and/or phase inverter. That's why the 3 Channel's FX send and output control are tied together and why they recommend conservative volume settings on the preamp if using the FX loop. The kind of EQ-ing accomplished is akin to running an EQ in the FX loop, except for Channel 1. Channel 1 only uses the first 12AX7 before the EQ, using the second half of V1 to reamplify it and then runs into the FX loop. It has the most dynamics, because it passes through the least amount of amplification and has the tone stack so close to the input.

Channel 2 and 3 are run through 4 additional stages that alternate between squishing the signal to get a lot preamp distortion and then make-up gain stages that add gain to the squished signal. The end result is a much more compressed feel. (In amplifier design, distortion is the breakup accomplished by overdriving the valve and gain is only an increase in volume. The Gain knob should actually be called a Distortion knob.) By the time the tone controls come in, the overall character is set and the EQ kind of tailors it. That's why Mesa says to be conservative with the gain control. If you set it too high, the preamp has already squashed and re-amped the signal by such a degree that the tone controls have very little effect.

So, what's one to do to establish a bass tone in an amp with a TMB EQ at the end of 5 amplification stages? You control the bass by the value of resistors and capacitors on the cathode of the 12AX7s. It's called an RC filter and the type is a high pass filter. Attenuating the bass frequencies removes noise and unusable frequencies, and an overall tonal character of the low frequencies can be sculpted. From memory, the attenuation begins in a Recto at V1 right around 87 Hz and drops quite heavily below that. Channels 2 and 3 have differing capacitor values that switch with the channel and are partof the tonal difference between the two. They also attenuate low frequencies, but the exact value escapes me right now. Some drop tunings aren't even getting the fundamental notes of the first several frets of the low string amplified no matter what channel you're on.

Another influence over the tone between the channels is the Presence. Aside from being a different variable resistance, the Presence on Channel 3 is not a normal control. Presence is usually wired from a part of the phase inverter that has negative feedback from the output circuit being fed to it. Negative feedback reduces volume a little, but adds stability to the circuit. Channel 3 has a different circuit that fakes a real Presence. Channel 2 has the normal negative feedback type of Presence.

I calculated the stages a few years ago, but I don't remember most of the particulars. I also don't really want to print data sheets and do the math, either. I wouldn't expect the frequencies below 70 or 80 Hz to have much impact and it probably drops in value after 6 or 7 kHz. In any case, most 12" guitar speakers only reproduce (roughly) between 70 Hz up to 6 or 7 kHz, so any amplification above or below that has little consequence as tone. Going back to drop tunings, that means anything below a low D is probably not being accurately reproduced by a typical 12" speaker (the note may be sounding, but it's so low in dB as to not be audible). Anything above the high roll off might be reproduced as noise if it's reproduced at all. As I mentioned above, I've begun to cut frequencies over 8 or 9 kHz and it reduces some noise in high gain settings, but allows enough of a tail to not really affect the audible range.

Whew, ADHD.

 

[afu]

http://amps.zugster.net/articles/tone-stacks

I'ma try ta explain this.

Go down to "Three Knob". The wiper of the Treble pot runs to the volume pot, but it isn't pictured. The treble runs to the bass, the wiper of the bass goes back to treble, and the middle has a hot leg grounded and is connected from it's wiper to the same hot leg of the bass pot as the treble. Obviously, the treble pot has a huge impact from being both first and last in the circuit and having the other two wired to it. The middle pot has a large control over the bass, because one leg is "ground" (off) and the other is it's full potential as a resistor. As the wiper (variable element of the pot, leg #2) moves between it's full resistance potential and ground, it also affects the curve of the low mids of the bass as it's tied right to the bass pot. The bass' wiper has less of an influence over the circuit, as it's largest increases are below what the amplifier is reproducing, but turning the mid all the way up will increase the signal to the treble pot enough to potentially cause distortion.

The Tone Stack Calculator will show it in a graph. You can replace the values of the Marshall tone circuit with the values from the Recto schematic if you want to.

 

[afu]

I got curious and looked up a 3 Channel schematic. This one has a mute switch. It's probably for a Dual/Triple Reborn. On this schem, Channels 2 and 3 had normal negative feedback to the Presence control with the following differences: Channel 2 Raw and Channel 3 Modern have alternate Presence circuits. It is a RC high pass filter that grabs signal from between Treble and Master pots down to the Presence pot. It (no matter which mode or channel) then goes to the Mid pot at the grounded lug. Channel 1 also has an alternate Presence circuit.

As far as I can tell, the coupling cap after the V1 switch that sends the signal to Ch's 2+3 is followed by a filter circuit to voice each channel differently just prior to another switch to the Gain knob. The modes also have a separate section that voices them in channels 2 and 3 individually. I know they made changes to the Reborn, but I'm betting that it was values of components more than full circuit changes. So some of this applies to the old 3 Channels.

The only other schems I found were for the 2 Channel models. Anyone have a 3 Channel one that isn't Reborn?

 

[ryjan]

That's great info man. Thanks for taking the time to post all of that.

 

[Shemham]

There's a load of information here that I consider outright false or at least largely misconceived so I try to correct a couple of things here.

Firstly, the crucial differences between Vintage and Modern mode is indeed in the presence circuit. Vintage mode utilizes NFB whereas Modern uses simply another pot to filter the highend to ground. Another relevant difference is in the tone stack circuit where the vintage mode is assumed to be used with 500pf treble cap where as modern mode is supposed to be used with 680pf treble cap value. These two modes share the exact same coupling caps, cathode resistors and caps as well as grid resistors so no differences in the gain stages.

The channel cloning feature is what complicates how the different models use these features. I tried to create a table of features for each amp model to shed some light how the amps function between the channels on Vintage and Modern modes:

2 Channel Recto:
-orange higain: 500pf treble cap, NFB used
-red modern: 680pf treble cap, separate presence circuit & NFB not used
-red vintage: 680pf, both NFB and the separate presence circuit used
-orange modern: 500pf treble cap, separate presence circuit & NFB not used

Non-multiwatt 3 channel Recto:
-orange vintage: 500pf treble cap, NFB used with 22k presence pot
-orange modern: 500pf treble cap, separate presence circuit with 22k presence pot
-red vintage: 500pf treble cap, NFB used with 100k presence pot
-red modern: 680pf (500pf parallel to 180pf) treble cap, separate presence circuit with 100k presence pot
Additionally, according to the schematics floating around internet the presence circuit on the orange channel seems to have 33k resistor before the presence pot whereas the red channel seems to have 22k. Unless the data on the schematics is false, the 2 channel Rectifiers, Road Kings and Roadsters seem to utilize 22k resistor in this position for both orange and red channel.

Multi watt 3 channel Recto:
Orange and Red channel
-vintage mode: 500pf treble cap, 22k
-modern: 680pf (500pf parallel to 180pf) treble cap, separate presence circuit with 100k presence pot

Secondly, the difference in gain between Modern and Vintage mode is not as great as assumed. Even if the NFB may somewhat reduce the gain in Vintage mode, its effect is more noticeable in the feel, volume and dynamics of the mode. Practically you can get about as high gain sound with Vintage as with Modern, but Vintage ends up sounding more balanced/controlled and smoother.

The raw mode (at least in the non-multi watt 3 channel model) is very different because it actually reduces the amount of gain available for the circuit by dropping the 680k/.002 highpass filter before gain pot and instead uses the 2M2/82pf circuit which would be in parallel with the former circuit in Vintage and Modern modes. In the original 2 channel models this circuit was one of the components used to form Orange Clean sound. If my deduction is not flawed, the original Rev C/D's clean mode was VERY close current Raw mode.

afu: The schematic that you're viewing is most likely a schematic for the original 3 channel model. To this date I haven't found any leaked Reborn schematics floating around Internet. I've been told that Mesa only provides those directly to amp techs.

I hope I clarified some things rather than further confused the discussion...

 

[afu]

http://schems.com/manu/mesaboogie/boogie_dualrectifier_3ch_solo_head.pdf

Look at page 7. The Presence controls have switching between using NF and the alternate circuit. Vintage and Modern in Channel 2 use NF and Raw and Vintage in Channel 3 use NF. The pot value will make the taper and frequency different, but the Presence controls change with the modes.

You are correct about the cathodes. The main difference between Channel 2 and 3 before the tone stack is the filter circuit between V1 and the Gain pots. My memory was from the 2 Channel schematic and the cathode switching it has.

I just edited this, because you are right about the distortion between Vintage and Modern. There is little difference. I think the thing for me was always switching between Modern Channel 3 to Vintage Channel 2 required some major differences to achieve a complementary sound. In Channel 2, I switched between Modern and Vintage with the tones at noon and the presence off, adjusting only the volume to compensate for the differences. The distortions are incredibly similar, but the voicings would require changes to have each one in it's sweet spot. That's the major difference between the distortion sounds in Modern and Vintage; voicing.

I'm man enough to say when I'm wrong. I got a little turned around thinking about the cathode switching in the older amps, it's been awhile since I'd looked, and I should have referred to something before stating "fact" when my memory was fuzzy in the first place.

 

[Shemham]

http://schems.com/manu/mesaboogie/boogie_dualrectifier_3ch_solo_head.pdf

Look at page 7. The Presence controls have switching between using NF and the alternate circuit. Vintage and Modern in Channel 2 use NF and Raw and Vintage in Channel 3 use NF. The pot value will make the taper and frequency different, but the Presence controls change with the modes.

I tend to take the information on these schematics with a small dose of reservation as some of the values have been found false. For instance, 2 channel Rectifier schematics available on schems.com show the gain pot values to be 1M ohm while they actually are 250k/220k ohm. The official manual for the 3 channel head actually suggest that you could change the presence pot to make the channels essentially same (save the treble cap's value and treble roll-off) which sounds fallacious if the modes still alternate NFB on the channels as the scribbles on the page 7 of the schematic suggest. But if those notes are correct then I naturally stand corrected.

I didn't mean to direct my previous message to you, but rather just as a contribution to the discussion as a whole. Sorry if I made it seem otherwise.