Valves in pedals that run on low voltage...hype?

[clubhouse]

I have some pedals here that use valves in the circuit to gain boost the audio signal through them. They typically have 12VDC PSUs. I've read about 'starved plate' designs in pedals that incorporate valves and there is some argument as to the effectiveness of these designs to the point of the valve adding no discernible colouration above the other gain boosting components in the circuit.

I've used an ART MP pre-amp (12AX7A) as a line driver for a board of effects...swapping valves (brands and 12A/ECC/mil spec variants) made no aural difference...suggesting to me that the valve had little influence in the circuit (harmonic filter?) and the heavy lifting was being done by the ICs and diodes and shit. And then there's the ol' Ibanez Tube King and others.

In this case is the valve there for marketing hype or does it actually contribute gain and tone (harmonic richness?) in discernible/qualifiable amounts relative to the influence of the rest of the circuit components?

Effectrode and Kingsley apparently run under more amp like power conditions. The Effectrode Delta Trem I have has a PSU that supplies 12VDC @ 2A so I'm more inclined to believe there is real valve gain and tone massaging going on there...yes?

[olegmcnoleg]

If you already have a decent tube amp, do you really need more tube 'colour' in your signal chain? I've only really tried tube overdrive, not any other tube pedals, so I don't know the answer. But I think it is an interesting question.

[Slowy]

Sorry to be boring but aren't you asking the wrong questions?
Do you hear a difference?
Do you like what you hear?
Do you like it enough to open your wallet?

'Cos out here in interwebz land you won't get an answer; you'll get every answer.

[Slowy]

If you already have a decent tube amp, do you really need more tube 'colour' in your signal chain? I've only really tried tube overdrive, not any other tube pedals, so I don't know the answer. But I think it is an interesting question.

I think Tube tremelo might be an actual thing..

[clubhouse]

If you already have a decent tube amp, do you really need more tube 'colour' in your signal chain?

I'll leave that one for the personal nature of the player's idea of their own audio signature.

Man, you should have seen some of the lengths we went to, to get a vocalist's recorded sound sounding anything like the sound in the producer's mind. Often caused by having to use equipment that had a unique sonic signature because of availability and cost. Valve pre mic into valve pre into valve compressor with a dash of valve eq into DAC or to tape for another layer of analogue sauce...there was sonic band-aids of all sorts to massage the room sound into what sounded right for the singer, the song and the mix.

[clubhouse]

Sorry to be boring but aren't you asking the wrong questions?
Do you hear a difference?
Do you like what you hear?
Do you like it enough to open your wallet?

'Cos out here in interwebz land you won't get an answer; you'll get every answer.

I don't think so. It's a technical question around the nature of valve specification and if running a valve out of spec, with such a low power supply (if that is indeed what is happening) can that affect the aural perception of signal fidelity, or, if running a valve out of spec is irrelevant (in such designs) because the valve is doing nothing except having the heater glow/pretending to be in the audio circuit.

Often, I'll buy a pedal on reviews because no one local stocks it for me to audition it in person. As I wrote, I could not hear a difference between valve brands and types when I rolled some through the little ART MP but I only did that some time after buying the thing, mostly on price per dB for the noise floor...not valve colouration. That was, I hoped for, a bonus that I could finesse from it with some rolling.

I notice a difference in the Delta Trem with the pedal engaged, but with the effect depth rolled off, compared to pedal bypassed. It uses a raysistor device (similar but different to the opto/LDR roach in a Fender amp vib/trem) to do the wobble and sway and the valves drive the circuit in an amp like way. I very much like the colouration...it's subtle but I'm a player that has to feel comfortable with my sound to feel confident and comfortable playing what's in my head...allows to me focus on what I'm doing more. (I will incessantly knob fiddle to dial in my sound otherwise...can't string two notes together for cringing.) It's a more mid-rangey sound, harmonically pleasant and touch dynamic sensitive. I'm happy and it suits one of my rigs where I can use something like that. If it sucked and I had no alternative application for it, I would've sold it on.

ART MP is none of that. I bought it for different reasons and adapted it to being a board, signal driver. It has done well with Oktavia, Rode, Beyer Dynamic and AKG mics but fell far short of the silky complexity of a Neumann U47 or even an AKG SolidTube. It was cheap and portable.

[olegmcnoleg]

If you already have a decent tube amp, do you really need more tube 'colour' in your signal chain? I've only really tried tube overdrive, not any other tube pedals, so I don't know the answer. But I think it is an interesting question.

I think Tube tremelo might be an actual thing..

Indeed it is, but surely one has this built into the amp

[Jay]

I have some pedals here that use valves in the circuit to gain boost the audio signal through them. They typically have 12VDC PSUs. I've read about 'starved plate' designs in pedals that incorporate valves and there is some argument as to the effectiveness of these designs to the point of the valve adding no discernible colouration above the other gain boosting components in the circuit.

I've used an ART MP pre-amp (12AX7A) as a line driver for a board of effects...swapping valves (brands and 12A/ECC/mil spec variants) made no aural difference...suggesting to me that the valve had little influence in the circuit (harmonic filter?) and the heavy lifting was being done by the ICs and diodes and shit. And then there's the ol' Ibanez Tube King and others.

In this case is the valve there for marketing hype or does it actually contribute gain and tone (harmonic richness?) in discernible/qualifiable amounts relative to the influence of the rest of the circuit components?

Effectrode and Kingsley apparently run under more amp like power conditions. The Effectrode Delta Trem I have has a PSU that supplies 12VDC @ 2A so I'm more inclined to believe there is real valve gain and tone massaging going on there...yes?

I have had the pleasure of playing with the guts of a BK Butler solid state amp which employs a single triode valve as a separate pre-amp. Its anode is powered by a 34VDC rail and the valve gain certainly is noticeable and provides a distinct and interesting audio spectrum imo. The starved plate design appears to be real if one believes Butler's design and on his webside there is documentation to explain how it works (or somewhere on a website anyway).

I am unsure if his pedals also use the 34VDC rail but I would'nt be surprised if they do.

[NippleWrestler]

In the case of Effectrode pedals they run the tubes at around 300 VDC. That's not starving the plates, that's running them like a tube amp would.

Here's what he said "Yes, the tubes operate at 300 Volts D.C. All pedals incorporate a transformerless high voltage power supply which is fully regulated and smoothed to ensure low noise. There are some manufacturers operating tubes at voltages as low as 12 Volts. I guess this is for economic reasons or for lack of ability in power supply design. It’s certainly not for better tonal quality because low voltage operation (current starvation) of tubes sounds terrible"

I've messed around with tube pedals but without the mass of architecture needed in the power supply, and the actual PSU itself, it seemed like a giant gimmick with zero tangible benefits outside of marketing.

Here's a handy graphic basically showing the more voltage the more the output until you reach saturation. You cant get there without volts.



I suppose you could run a series of solid state gain stages into a tube in a pedal enclosure to get the tube to do something off a 9v supply.

[olegmcnoleg]

I have some pedals here that use valves in the circuit to gain boost the audio signal through them. They typically have 12VDC PSUs. I've read about 'starved plate' designs in pedals that incorporate valves and there is some argument as to the effectiveness of these designs to the point of the valve adding no discernible colouration above the other gain boosting components in the circuit.

I've used an ART MP pre-amp (12AX7A) as a line driver for a board of effects...swapping valves (brands and 12A/ECC/mil spec variants) made no aural difference...suggesting to me that the valve had little influence in the circuit (harmonic filter?) and the heavy lifting was being done by the ICs and diodes and shit. And then there's the ol' Ibanez Tube King and others.

In this case is the valve there for marketing hype or does it actually contribute gain and tone (harmonic richness?) in discernible/qualifiable amounts relative to the influence of the rest of the circuit components?

Effectrode and Kingsley apparently run under more amp like power conditions. The Effectrode Delta Trem I have has a PSU that supplies 12VDC @ 2A so I'm more inclined to believe there is real valve gain and tone massaging going on there...yes?

I have had the pleasure of playing with the guts of a BK Butler solid state amp which employs a single triode valve as a separate pre-amp. Its anode is powered by a 34VDC rail and the valve gain certainly is noticeable and provides a distinct and interesting audio spectrum imo. The starved plate design appears to be real if one believes Butler's design and on his webside there is documentation to explain how it works (or somewhere on a website anyway).

I am unsure if his pedals also use the 34VDC rail but I would'nt be surprised if they do.

I had a Buttler-made valve OD unit, (Chandler). It was awesome, and to tweak it you could swap preamp tube types. It was rack mounted, so I sold it when I stopped using a rack. I’m not sure if it added much to a revved up tube amp, but I used it anyway

[clubhouse]

Thanks for the input, cats. The engineering explains my anecdotal, aural observation and I have a better understanding of the relationships involved. That helps a lot for me to better interrogate design and specs on any units I might think of auditioning in the future…another layer of screening out the blind alleyways before ‘paying to try’.

My fault, with the ART MP pre, for thinking I might be able to squeeze something out of it that it was never designed to supply. I’ll still hang on to it as it makes for a handy DI for my bass board.

[FuzzMonkey]

I am also in the opinion that by the time you've designed a power supply to run the tube at amp voltages, the cost-to-benefit ratio doesn't really add up.

I am not a fan of tubes running at low voltages but Steve Bartlett of Baja Electronics would be the man to ask about this subect. I know he has a lot of expertise in this area and has done a bunch of pedal designs using tube in pedals. Both subminiature and 12AX7-sized.

After all, 99.99% of guitarist don't seem to have an issue putting some form of solid-state amplification or clipping in front of their tube amp.

[RectifiedAmps]

Here’s a good discussion of this topic:
http://www.valvewizard.co.uk/Triodes_at ... encowe.pdf

It gets pretty technical and is focused on pedal design, but you can get a sense of the benefits and limitations.

[vintage52]

If you already have a decent tube amp, do you really need more tube 'colour' in your signal chain? I've only really tried tube overdrive, not any other tube pedals, so I don't know the answer. But I think it is an interesting question.

I think Tube tremelo might be an actual thing..

Indeed it is, but surely one has this built into the amp

Or the Origin Effects Revival Trem.......

[Jay]

Here’s a good discussion of this topic:
http://www.valvewizard.co.uk/Triodes_at ... encowe.pdf

It gets pretty technical and is focused on pedal design, but you can get a sense of the benefits and limitations.

That is a great article, thanks