The All Tube Path, Non Channel Switching Thread?

[jack daniels]

One or more of the MF members that are EE majors can/could expound on the simple circuit versus complex circuit pros and cons much better than I can. I'm happy to leave that discussion in their capable hands.

 

[30watt]

I LOOOOVE my VI JCM800 combo from 83.....but I also love my Artist combo, my Reverb 75 and my channel-switching 800 combo.

Fow what I do, a small (5 pedals) board is necessary. If I were playing my favourite brand of music (Bad Company, Free, Skynyrd, Stones, Quo) and that was all I did, my signal path would be

PRS (Dragons) > JCM 800 vertical input combo.

The sound would be crunchy (think Rock and Roll Fantasy or Gimme Three Steps tone) with the guitar on bridge pup at 10, slightly driven at 7, and cleaned up when coil-split.

I'd have some reverb and maybe a splash of delay put on by the FOH engineer.

That, IMHO, would be a setup that would be simple and tasty. But I can't do that, as I'd be WAY too loud for my current venues and not have any variation to go from Chuck Berry to Supremes to Van Morrison to Neil Diamond.

Doesn't mean my tone is bad. It isn't perfect, but that's the nature of what I play-compromise is essential.

YMMV.

 

[JLBIII]

Since there is no radio rock anymore, just oldies like Rage Against the Machine and Bush, I'm watching country closely. Les Pauls through non channel switching Marshalls seem to be a growing segment there. Another oddity I've seen is jazz being played with JTMs and superbasses. I really think the classic amps will always have an following, especially for players who choose to use their fingers more than their feet.

Rage Against the Machine and Bush oldies? Man, I feel like a frickin' dinosaur now. Only within the past couple months have I started using a 50 watt JVM. Before that it was original and reissue 1987's and a '83 2204. Most of the time I just use one channel on the JVM. No dirt pedals. My current main guitar only has a volume knob and 5 way selector switch. I use both all the time to get sounds and tone that I want. We only play originals so I'm not trying to duplicate anyone else's tone. To be honest my 2204 is still my favorite head to use but I'm still on a learning curve with the JVM. The 1987X has that classic Marshall tone, especially when playing my '76 LPC.

 

[Matt_Krush]

From a EE...I'll make this basic and try to keep it for guitarists...

I know this may blow some minds...but whether the amp is tube or solid state....YOUR GUITAR SIGNAL DOES NOT PASS THROUGH ANYTHING!

Repeat that capitalized part many times please.

An amplifier 'recreates' the minuscule signal sent by your guitar (or whatever you are amplifying). Whether the amplifier is a 12AX7, and op-amp, or a 'FET of some type, the signal does not go through it small and come out larger. The valve (tube) or FET allows electrons to flow from a much higher power source in direct proportion at a magnitude higher to the signal received. When a signal hits the tube's grid or a transistor's base...it goes no further. The larger signal is created from the DC power supplied by the transformer after it is rectified (or battery i.e. stomp-boxes). A good amplifier will follow that signal in magnitude & frequency.

So why then are tube amps more revered...or better sounding than solid state amplifiers for guitar?
It has to do with the Even and Odd order harmonics each type of amplifier creates. I'm not talking about playing techniques and pinch harmonics....I'm talking about Fourier analysis of frequencies...You hear them. You may not know it, but they are there. The Even order...it's what make tube amps (good ones) sound like..."Yeah...that's what I like".

Can the signal be degraded by more electrical components in an amplifier or effects chain? Sure. It can also be made better.

So is a simple circuit better than a more complex one? Yes and no...for serviceability complex circuits suck to work on and diagnose, but again tone is subjective.

If we are led to believe, that a simple circuit is best...then that would be what? a single 1/4 watt 12AX7 amplifier?
Being that a 12AX7 is basically 2 6AV6's....a JCM800 would then have 6 circuits in the preamp section (not including EQ) and 2 more for the EL34's.
So that's 8 electrical recreations of the input signal.

Many channel switching amps just kick in an extra 12AX7 or two...and maybe switch between different resistors for more/less gain.
Take for instance the JVM410. The actual amplifier circuit is as simple at the 800, there is just more of it. Not all of the circuitry is used at the same time...some of it is switched in and out. That is the versatility.

 

[marshallmellowed]

Let's just take this subject a step further, say I take a simple Fender amp circuit, and I add on the hi gain, and multiple channel circuits to that original circuit. When comparing the signal before and after the amp modification you're saying that the newly modded circuit will not affect the original signal and that said signal won't be degraded whether other channels are used or not? Hmmmm

First off, you're now changing the previous scenario, you're adding "hi gain", in addition to multiple channels. The previous scenario was single channel vs. multiple channels, so let's stick with that and not muddy the waters. Given a single channel amp and a multi-channel amp that uses relays for routing the signal through various paths, the fact that the signal is re-directed through use of relays will not degrade the signal in any way. The various channels will sound different, as that is the whole purpose of having a multi-channel amp, they may be voiced differently, have different gain structures, and so on.

The reason many old timers prefer the vintage amps of old is because of lack of additional B.S. in the circuit so as to make their signal as pristine as possible. There are phase differences in any circuit. The more intense and complex the circuit, the more phase differences. From electronic theory you have voltage leading current in an inductive circuit by 90 degrees, and voltage lags the current in a capacitive circuit by 90 degrees. Now just add more capacitors and inductors and viola....

I am one of those "old timers", and if we're talking about a complex switching amp, using IC's for switching the signal and op-amps for gain, then I would say yes, the signal is affected. I have no idea what you're talking about regarding your "voltage leading current in an inductive circuit by 90 degrees" statement, and I work in the field of electronics. Given two all-tube amps, one single channel, and one multi-channel, whether the signal in a properly designed multi-channel amp is degraded or not, is totally dependent on the switching components used, no more, no less.

 

[jack daniels]

First off, you're now changing the previous scenario, you're adding "hi gain", in addition to multiple channels. The previous scenario was single channel vs. multiple channels, so let's stick with that and not muddy the waters. Given a single channel amp and a multi-channel amp that uses relays for routing the signal through various paths, the fact that the signal is re-directed through use of relays will not degrade the signal in any way. The various channels will sound different, as that is the whole purpose of having a multi-channel amp, they may be voiced differently, have different gain structures, and so on.

You are forgetting the multiple channel amps that use the same tone controls or the same tone stack....

 

[marshallmellowed]

You are forgetting the multiple channel amps that use the same tone controls or the same tone stack....

No, I am not "forgetting" anything, it doesn't matter. You obviously do not understand signal paths and what does and does not have a negative impact on the signal. Like I said, using relays for switching does not degrade the signal, routing the signal of each channel through the same tone controls is irrelevant.

The JVM series is one of the best examples of an all-tube signal path amp using relays for all signal switching. Studying the schematics, it's obvious Santiago designed the amp with emphasis placed on versatility and retaining the integrity of the all-tube signal path.

 

[Trapland]

You can always play a multichannel amp using just ONE channel....it's no big deal.

No you can't always play a multi- channel amp using just one channel, at least if you want the same behavior as a single channel amp. You may be assuming everyone that uses a single channel amp just has one sound therefore one channel of a channel switcher is the same thing, it's not.

I use NO dirt boxes. I only use my guitar volumes (and pickup switch) to go from clean to crunch to lead. I do it with the master cranked. Although a rare few multi channel amps can approximate this, by far the majority cannot. The reason is simple, most multi channel amps are designed to get pretty much all of their distortion from preamp gain and use a dedicated clean channel for cleans. The clean channels don't clip enough and the gain channels don't clean up enough by reducing input. Getting most of your clipping from preamps usually doesn't get very clean when you roll down the guitar. Cleaner yes, but not as clean as.....

Many pre-channel switching amps can get tons of crunch from power tube and phase inverter clipping. This sort of clipping sounds to many human ears like it gets lots cleaner before it gets lots quieter. Sure a 2204 etc can run a lot of preamp distortion too, so the amount of guitar volume cleanliness varies, but one thing happens for sure.... running the least amount of preamp section needed to saturate the power section will make the amp clean up and be more sensitive to picking dynamics than getting similar feeling gain levels from the preamp only.

And as a side note...Marshall has made some brilliant modern channel switchers that emulate the cranked power stage sound and behavior. I could and have used a DSLs red channel almost exactly like I use a JMP. Near clean to plenty of saturated crunch on one channel with only the guitar. I think the JVMs sound stellar, but I could never get them to clean up with the guitar at the saturtion level I wanted with the guitar full up.

So you can sometimes use a multi channel amp on just one channel. But when it doesn't do what you need it to, it's indeed a big deal.

This is the fun of this thread, people use different amps different ways.

 

[marshallmellowed]

 

[mickeydg5]

As I said "Everyone is different." You like what you like. That has nothing to do with what others do. With my thinking one uses whatever it takes. I like versatility, lots of versatility.

 

[mickeydg5]

From a EE...I'll make this basic and try to keep it for guitarists...

I know this may blow some minds...but whether the amp is tube or solid state....YOUR GUITAR SIGNAL DOES NOT PASS THROUGH ANYTHING!

Repeat that capitalized part many times please.

An amplifier 'recreates' the minuscule signal sent by your guitar (or whatever you are amplifying). Whether the amplifier is a 12AX7, and op-amp, or a 'FET of some type, the signal does not go through it small and come out larger. The valve (tube) or FET allows electrons to flow from a much higher power source in direct proportion at a magnitude higher to the signal received. When a signal hits the tube's grid or a transistor's base...it goes no further. The larger signal is created from the DC power supplied by the transformer after it is rectified (or battery i.e. stomp-boxes). A good amplifier will follow that signal in magnitude & frequency.

So why then are tube amps more revered...or better sounding than solid state amplifiers for guitar?
It has to do with the Even and Odd order harmonics each type of amplifier creates. I'm not talking about playing techniques and pinch harmonics....I'm talking about Fourier analysis of frequencies...You hear them. You may not know it, but they are there. The Even order...it's what make tube amps (good ones) sound like..."Yeah...that's what I like".

Can the signal be degraded by more electrical components in an amplifier or effects chain? Sure. It can also be made better.

So is a simple circuit better than a more complex one? Yes and no...for serviceability complex circuits suck to work on and diagnose, but again tone is subjective.

If we are led to believe, that a simple circuit is best...then that would be what? a single 1/4 watt 12AX7 amplifier?
Being that a 12AX7 is basically 2 6AV6's....a JCM800 would then have 6 circuits in the preamp section (not including EQ) and 2 more for the EL34's.
So that's 8 electrical recreations of the input signal.

Many channel switching amps just kick in an extra 12AX7 or two...and maybe switch between different resistors for more/less gain.
Take for instance the JVM410. The actual amplifier circuit is as simple at the 800, there is just more of it. Not all of the circuitry is used at the same time...some of it is switched in and out. That is the versatility.

I kind of like this guy.
Like, like likelike.

 

[Trapland]

Wow... I never intended this to be an anti channel switching curmudgeon "we're the only ones doing it right" thead. Just a "I like my single channel amps and here's how I use them, any one else?" sort of thread.

I like (and have owned) most Marshalls, channels or not.... I just play these.

 

[mickeydg5]

Not arguing but perhaps you should not have mentioned other type of amplifiers.

 

[Trapland]

I did? I guess I did as examples, but never negatively. Heck, I really really like today's DSLs and JVMs. I think they sound amazing. The red channel on a JVM is the sweetest high gain sound ever. But for the way I use them, I would have to relearn my technique.

I guess instead of bashing amps that I clearly stated were excellent and understood as useful, I was more trying to defend the single channel players technique of using the guitar controls for everything. At lease I never said anyone was wrong for liking what they like, but I am hearing a bit of "we're wrong" for not using multi channel amps.

 

[spacerocker]

One or more of the MF members that are EE majors can/could expound on the simple circuit versus complex circuit pros and cons much better than I can. I'm happy to leave that discussion in their capable hands.

You don't need an "EE Major" to understand this stuff - just look at the circuit diagrams!

The JVM410 in Crunch Orange, for example, has exactly the same circuit topology as a JMP2203! - that's right - exactly the same number of valves, gain stages etc. All the other "complex circuitry" (by which I assume you mean extra valve gain stages) is switched out of circuit. Each channel has it's own Gain, Volume, and Tone Controls. These controls for the other channels are switched out of the circuit, so have absolutely no effect on the tone of the channel being played!

Think of a multi-channel amp like the JVM as a single channel amp that you can switch different settings into. You can switch in extra gain stages (just like when you use transistor stomp boxes in your pristine simple single channel amp circuit path), switch in different volume levels (via the channel volumes) or switch in different tone pot settings for each channel.

All the switching is done via relays (in the JVM at least) - so when a component is switched out IT'S OUT and can have no effect on the tone of the active circuit.

But with all the extra stages switched out, the JVM is basically a JCM800!

I have played 23 years with a single channel amp, and 7 years with a JVM (albeit modded) - I'm never going back!

 

[Gunner64]

Bottom line If it sounds good to you play it! And no matter what we use for amps our delays, choruses, flangers, ect. Do alter the signal right?. So even if you play a 59 Les Paul through an totally stock 68 plexi wearing homemade hemp underwear, if you use effects your running through the dreaded silicon, so there goes your pristine all tube signal path right? My opinion is If you like what your playing, no matter what it is, tube s.s. modeler, and it inspires you to play, and play better, more power to you. And lets face it some guys here can make anything sound great, I wish I was one of them.. I need all the tonal help i can get..Id play with tubes in my pockets if i thought it would help, Dampers on of course.

 

[marshallmellowed]

It's true, if your ear holes like what's coming out of the speaker, use it.

 

[Stemiles90]

guitar-class 5+ fingers/vol pot ,guitar-fender drri + fingers /vol pot = happiness.

 

[iron broadsword]

I've played a lot of amps and been tinkering with circuits for years.. I'm no expert like I said but think of it like train tracks. When they flip the switch and the track now goes left at the Y, the entire train goes left. That guy in the caboose wishing they were going right is gonna be sad cause unless he jumps he is going left too.

When something is out of the circuit, it's out. It's an on-off thing. And while it's true that many multi-channel amps are voiced differently than your classic single channel amps, there's no reason you couldn't build an amp with your 3 favourite preamps from your fav marshalls and put them into the power section of a classic 1959slp. If one of those preamps were from the same amp, then you'd legit be playing that amp when on that channel. The JVM is a great example. It has a bunch of classic preamps, and a stiffer power section for the modern thing.. but with a few tweaks you can get the power section to do the classic thing and have your cake and eat it too.

 

[spacerocker]

When something is out of the circuit, it's out. It's an on-off thing. And while it's true that many multi-channel amps are voiced differently than your classic single channel amps, there's no reason you couldn't build an amp with your 3 favourite preamps from your fav marshalls and put them into the power section of a classic 1959slp. If one of those preamps were from the same amp, then you'd legit be playing that amp when on that channel. The JVM is a great example. It has a bunch of classic preamps, and a stiffer power section for the modern thing.. but with a few tweaks you can get the power section to do the classic thing and have your cake and eat it too.

Yes, you have hit the nail right on the head! I get a bit tired of reading how single channel amps are soooo much better than multi-channel amps because of their "simpler signal path" and how "they haven't got all that extra stuff in there sapping the tone". These sort of comments usually come from those who haven't got a clue how these amps work, and are just jumping to conclusions about how the amps work to back-up their pre-conceptions!

There ARE reasons why stock multi-channel amps don't sound exactly like vintage amps, but these reasons are seldom to do with the complexity or otherwise of the signal path! Usually multi channel amps are voiced in such a way that they can cope better with high gain channels, as well as clean and crunch channels. Specifically, this is due (on the JVM at least) to:

1) The use of a resistor rather than a choke in the power amp circuit
2) The lack of a "treble peaker" circuit used on the JCM800s
3) The value of the plate resistors (chosen for more gain - in itself an old way of hot-rodding 800's)
4) The voicing of the tone stack (more trebly on older amps, more mid-focused on modern ones)

none of these differenecs are due to signal path complexity, but component choices to get a more versatile amp overall. As Iron Boardsword says - most of these changes are easily modded to produce a multi-channel amp, with a more classic sound (like mine!). What's not to like?