Amps question/complaint

[Baba]

Spurred by a PM, but why the fuck IS it that most amps (still to this day), give you modes/options that you cannot get to with a footswitch or midi? I know that:

1. Not everyone plays live, or NEEDS that, especially if you're recording one track at a time.
2. There are plenty of amps that DO, and I've had them, (Marshall DSL, most Hughes and Kettner offerings, and the like).

Is it simply a cost thing?

This came from a discussion about the PRS MT-15 v2, and while I think of it, another amp I simply cannot use to it's potential, the 5150 Iconic. Don't even get me started on Mesa/Boogie, although I haven't paid much attention to them, maybe it's different these days.

In the case of the Iconic, it actually has a really nice sounding clean mode AND crunch mode, on channel 1, but the ONLY way to use both, is by pressing a button. The DSL rectified this with midi, but EVH? Nope. Sorry. Too bad. Pick one, not both.

 

[Orvillain]

I think that it's really difficult to fit that many relays into a box, and I don't think many micro controllers are up to the task of pushing the kinds of voltages inside an amp around, in order to simplify and digitize the switching technology.

 

[Baba]

I think that it's really difficult to fit that many relays into a box, and I don't think many micro controllers are up to the task of pushing the kinds of voltages inside an amp around, in order to simplify and digitize the switching technology.

So, I know absolutely nothing about that, but, for example, the Hughes and Kettner Grandmeister Deluxe 40 crams an awful lot into a very small box, including effects, so . . .

The DSL solved this with midi or their footswitch. That's what I'm talking about. A LOT more amps should be like the DSL.

 

[Chocol8]

As a counter point, I do not need the switching capability, and I avoid it like the plague.

1) For playing reasons, I prefer to keep the amp tone simple, and not change it song to song or within a song. Pedals give more than enough variation.

2) I want my tube amps simple for reliability and easy repair when needed. No stacks of PCB boards that need to come out for simple maintenance, and no banks of relays that can and do fail. The inside of a tube amp is a hot inhospitable place, so keep it simple, repairable, and minimize the components.

 

[Tenebris]

multifunction footswitches and their cords also become a giant point of failure that can impact lots of different use cases, compared to (for example) a toggle switch on the back of the amp that changes between two or three modes. and if a switch is going to cause a big volume change or require like 90 per cent of players to redial the amp, you may as well put it somewhere it's not going to get hit accidentally.

 

[laxu]

As stupid as it is, many amps still use "one function per cable" 7-8 pin DIN jacks instead of MIDI. I don't understand why, to me it makes zero sense and can't be any real cost thing either. MIDI would be much more suited for complex switching. So that already limits what can be footswitched.

Then we have preamps. These might be done as "crunch channel adds an extra gain stage, lead channel adds a further gain stage" or as fully discrete preamps like each channel on a Mesa Mark V for example. This can then lead to some compromises like your two favorite modes being on the same channel and thus not footswitchable. But these would not make sense to footswitch since you have to reconfigure the whole channel for a good sound.

Then there's features that don't make a whole lot of sense to footswitch. Like most of the time there's not much benefit to having footswitchable power scaling due to volume differences. You might also run into issues like a popping sound when that feature is switched, which you don't want to happen going into e.g your solo sound.

The H&K Grandmeister stuff seems to be extremely complicated with lots of microcontrollers to handle the ability to save pot settings and whatnot.

 

[Desertdweller]

I think that it's really difficult to fit that many relays into a box, and I don't think many micro controllers are up to the task of pushing the kinds of voltages inside an amp around, in order to simplify and digitize the switching technology.

The JMP1 and Triaxis preamps could do this 30 years ago though. I think @Baba has a good question.

 

[Orvillain]

@santiall in your professional ppinonion??

 

[Frodebro]

I would think that people who are into gear with massive tonal capabilities and switching have probably moved well away from traditional heads or combos and are running racks or digital. Tube amps are carbureted engines in a fuel injected world.

 

[EOengineer]

Just thinking about something like a Mesa Mark V, I would expect footswitching through all those modes would incur volume level mismatches due to gain staging differences, at which point you’re having to add a bunch more volume knobs.

Actually the Mark III is a great example of the perils of that. The rhythm channel was really just another mode, and one that was missing a volume control from the factory. The R2 mod (adding a volume on the back of the amp) is by far the most common mod on that amp. I couldn’t use R2 without it.

 

[santiall]

@santiall in your professional ppinonion??

hmmm, I guess it is a fair question. In many cases it is both a traditional reason ('proper' tube amps do NOT have anything digital inside), then add lack of knowledge of amp designers and also that back in the day, programming a microcontroller wasn't as easy as it is nowadays. You needed the micro, an external EPROM that most likely needed to be erased by UV light, the firmware was done in assembler, the in-circuit emulator costed an arm and a leg, etc. etc. Just look at a Marshall 6100 for example, and all that was actually expensive.

The JVM for example has a tiny 8bit micro that costs less than a dollar and does all that and more, and it is programmed in C as by the late 90s the compilers and in-circuit emulators started being much more capable.

Then there are other hurdles, to make everything midi-controllable you need to start replacing switches with relays, handling everything digitlaly, etc. For example a bright switch which is a simple short of a capacitor around the gain control becomes a switch that goes to a micro and a relay that is controlled by the micro, then you need to add power supply for the relay and bring the power to where the relay is physically in the circuit. Multiply that by a number of relays and the physical circuit layout can become complicated so then you ask yourself if it is worth the hassle.

On the other hand, if the switching is complicated, like in many multi-channel amps, it is so much easier to implement a microcontroller to handle everything than hardware logic. Once you have the micro in there, it is pretty much striaghtforward to have midi capabilities as well.

Regarding fully controllable amps, I think the only ones that is 'full' tube is the Triaxis, apart from the 'dynamic voice' (which doesn't have anything dynamic in there btw), everything else is tube and the circuit is pretty much the same as the preamps in some Boogie amps. The Marshall JMP-1 is pretty much a solid-state circuit with a couple of tubes here and there so you don't need to deal with high voltage analog signals which you can do with digital potentiometers.

The Hughes and Kettner amps are like the JMP-1, a solid-state preamp circuit with a tube here please a tube power amp, again, 'easy' to control with off-the-shelf digital potentiometers. Also the Marshall MG amps are fully programmable with digital pots and they are cheap.

I guess amps like the Boogies MkIV or the Roadsters would benefit a lot with a microcontroller instead of the hardware logic that they have inside. Specially the Roadsters with have a full blast pop when you switch one of the channels for the first time. That would be easily avoidable with a little micro inside handling the switching timing.

I don't know, I personally nowadays add a microcontroller as soon as I have more than 2 relays to control. The micro is probably 0.5 USD or less and I can program the switching easily rather than having to deal with a fixed hardware. Whether having midi or not depends more on the type of amp, I do understand that sometimes is an overkill and that not many people actually uses it.

 

[TSJMajesty]

This is a big reason that attracted me to the MP-1 back in the day. I too didn't "get" how you were supposed to access various tones from an amp while playing live. Even if I didn't need them during a song, what was I supposed to do for a different song, change amp settings btw songs? (This is in the context of a cover band, and I wanted my tones to be as close to the song we were covering, as possible.)

So having an amp with MIDI-footswitchable presets seemed like a no-brainer for me, and I used that rig for decades.

 

[santiall]

This is a big reason that attracted me to the MP-1 back in the day. I too didn't "get" how you were supposed to access various tones from an amp while playing live. Even if I didn't need them during a song, what was I supposed to do for a different song, change amp settings btw songs? (This is in the context of a cover band, and I wanted my tones to be as close to the song we were covering, as possible.)

So having an amp with MIDI-footswitchable presets seemed like a no-brainer for me, and I used that rig for decades.

yeah, the MP-1 was mostly done with digital potentiometers too, coincidentally the same ICs as Marshall used in the Marshall JMP-1 later on.
The MP-1 also had some clever gain control with matched pairs of light-dependent resistors, which then Mesa Boogie copied for the Triaxis (and they even patented them...). MB used that control all over the circuit so you don't have to worry about signal voltages. The digitally controlled potentiometers only can take about 30V peak to peak, so you pretty much can't use them anywhere in a traditional amp circuit without some tricks.

So yeah, it may look like an obvious feature but there are some technical hurdles that in many cases aren't worth the hassle.

btw, quite interestingly, the distortion in a JMP-1 doesn't come from the tubes, but mostly by the tubes overdriving an analog switch after the cathode follower, same as the Jose amps use diodes to clip the signal. I don't think we'll ever know if that was done on purpose or it is a happy accident...

I did start a JMP-1 re-issue quite a few years ago, maybe 2013?, as many people was asking Marshall to start making it again but it was when all the rack stuff went out of fashion an you could buy a used JMP-1 for 100USD so it was never pursued.