Anyone understand starved plate designs?

[jeffamm]

Anyone understand "starved plate" designs?

I'm trying to get a good understanding of "starved plate" designs used for some tube amplifier effects. I understand that they operate at very low voltages but what else is meant or implied by the starved plate? What is the theory of operation?

 

[turbo]

This is a method of simulating tube distortion. It is not very realistic and not very usable if you are a musician.

One of the cheapest ways of emulating a tube amp is to provide some even-harmonic distortion in the output while allowing sharp transients to sag a bit due to the inability of the power supply to keep up with demand. The best way to meet these goals is to play through an actual tube-driven amplifier.

Play through a healthy Fender Champ (50's-60's), and then give up your allegiance to SS amps. It will happen.

 

[jeffamm]

OK thanks for the rant, I guess, LOL, but I'm still looking for some real insight into starved plate designs. Anyone?

 

[sophiecentaur]

Doesn't it just mean what turbo was implying? When there is insufficient standing current available from the power supply / anode load to cope with the dynamic demand of the Anode (plate). This will cause premature saturation (Sounds like an old man's disease!) and distortion.

 

[sophiecentaur]

This is a method of simulating tube distortion. It is not very realistic and not very usable if you are a musician.

One of the cheapest ways of emulating a tube amp is to provide some even-harmonic distortion in the output while allowing sharp transients to sag a bit due to the inability of the power supply to keep up with demand. The best way to meet these goals is to play through an actual tube-driven amplifier.

Play through a healthy Fender Champ (50's-60's), and then give up your allegiance to SS amps. It will happen.

Oh turbo. You quaint old fashioned thing. Of all the colours of sound that are available nowadays, why are you still so wedded to what happens to come from a lousy amplifier technology? It's like deciding to climb Everest with a tweed suit and hobnail boots or using gut strings on a guitar - just an exercise in nostalgia. Do you still listen on 78s? Same thing.

I have a feeling I'm in for a slapping.
I'm surprised someone hasn't come up with a fast DSP that will give you any characteristic one could want and with no appreciable delay. Or have they?

 

[turbo]

I'm surprised someone hasn't come up with a fast DSP that will give you any characteristic one could want and with no appreciable delay. Or have they?

Not yet, nor will they in the foreseeable future, IMO. For the last 20 years, manufacturers have touted their tube-emulation gear in the music rags, and none has even come close.

 

[sophiecentaur]

Wot no slapping? Just a sensible answer?
I can't see why there would be a problem nowadays with processor speeds in GHz. You could almost simulate the path of every electron through the tube at that rate! Are they really trying or are they like Kodak used to be - always a couple of new film emulsions up their sleeve to launch when the opposition turned out a new one. Maybe they don't want to be bothered. They can sell enough without diverting from their existing systems. That would eat their profits and they probably have shares in a valve factory in India.

 

[jeffamm]

Doesn't it just mean what turbo was implying? When there is insufficient standing current available from the power supply / anode load to cope with the dynamic demand of the Anode (plate). This will cause premature saturation (Sounds like an old man's disease!) and distortion.

Sophie, yes I can infer that from the name, but was hoping to find something more authoritative or theoretical. I think the actual limiting factor is not the current available from the power supply, but the size of the resistive load, but same idea.

 

[sophiecentaur]

It's probably just a slang name, in any case. If you know how to drive a valve then you can make it distort how you want. If you can't find the term "starved plate" then look up "Valve distortions" or "valve sound". You're bound to bump into some knowledgeable nerd somewhere - but I don't think he's reading this thread!

Just did a search on Starved Plate and thermionic valve. There are many hits.

 

[jeffamm]

Yes many hits with the same one liner repeated over and over. Been all over Google on this, thanks.

 

[sophiecentaur]

Ignore it then! It's someone's own special term then.

 

[jeffamm]

No, it's a term that's been around for a long time, and has some specific design meaning. I'm just looking for the source of it.

Why was my thread hijack image removed by the way?

 

[sophiecentaur]

Was that image relevant? In the spirit of the forum?

 

[berkeman]

Why was my thread hijack image removed by the way?

Welcome to the PF.

 

[turbo]

If you run tubes at low voltages (starved) they really do not contribute to the tone of the amp - they are there as a marketing ploy. There are all kinds of amps out there with hybridizations of tube/solid-state. None of them sound like a real tube amp.

If an amp-maker could come up with a SS design that distorts, overdrives, and sags like a Fender 5E3 (tweed Deluxe), they could make a mint. The problem is that such an amp has a very dynamic interaction with the player and with the signal fed to it, and that feel is impossible to model with DSP gear, despite the hype in the guitar rags.

 

[sophiecentaur]

If an amp-maker could come up with a SS design that distorts, overdrives, and sags like a Fender 5E3 (tweed Deluxe), they could make a mint. The problem is that such an amp has a very dynamic interaction with the player and with the signal fed to it, and that feel is impossible to model with DSP gear, despite the hype in the guitar rags.

So how could it be that, quite randomly, the first amplifying device to be invented produced an inherently 'better' sound and gives more to the player than any subsequent technologies? That sounds like saying the dinosaurs were somehow superior to the mammals, which came later. Don't bring up Stradivarius Violins please because I haven't an answer except that they probably got better with age. There will never be the possibility of a direct A B comparison with a modern instrument.

People are naturally conservative and that's an end to it. There are enthusiasts who will tell you that old sports cars 'handle' better than modern ones because they allow the chassis to move. They don't win races though, do they?

 

[jeffamm]

Was that image relevant? In the spirit of the forum?

Given that the thread is getting hijacked, I think it was very relevant. I haven't used this forum much so I don't know what the "spirit" of it is, but given the hyperbolic off-topic rants my question has generated, it seemed to me to be in spirit. Here's the link to the image, you can decide for yourself

http://www.jontanis.com/gallery/d/3429-2/thread_hijack.jpg"

 

[jeffamm]

If you run tubes at low voltages (starved) they really do not contribute to the tone of the amp - they are there as a marketing ploy.

Sorry, but this is just ignorant. I really didn't come here to debate the merits of a starved plate design for guitar effect purposes, but if you insist on it, I won't shy away.

If an amp-maker could come up with a SS design that distorts, overdrives, and sags like a Fender 5E3 (tweed Deluxe), they could make a mint.

True, but really has nothing to do with the first quote.

You are free to not like starved plate effects, but why do you need to attempt to squelch a conversation about them?

 

[jeffamm]

welcome to the pf.

tnx 73

 

[sophiecentaur]

Given that the thread is getting hijacked, I think it was very relevant. I haven't used this forum much so I don't know what the "spirit" of it is, but given the hyperbolic off-topic rants my question has generated, it seemed to me to be in spirit. Here's the link to the image, you can decide for yourself

http://www.jontanis.com/gallery/d/3429-2/thread_hijack.jpg"

If you don't know the 'spirit' then look at a few random threads. You may not find too many random / irrelevant pictures there. People tend to be more interested in some Science and possibly sensible discussion. I think you knew what I meant, really. Just because you may say there's some possible political message in the picture, it's really not the place for it. I might hazard a guess that you are 'quite young'??

 

[jeffamm]

If you don't know the 'spirit' then look at a few random threads. You may not find too many random / irrelevant pictures there. People tend to be more interested in some Science and possibly sensible discussion. I think you knew what I meant, really. Just because you may say there's some possible political message in the picture, it's really not the place for it. I might hazard a guess that you are 'quite young'??

I think of myself as young, yes. I'm 50. If an image of terrorists holding a hostage is considered political here, it suggests there are folks who agree with the terrorists. I think it's just an amusing way to point out that someone is hijacking the thread. So is the spirit here to be both unhelpful and ill-humored?

 

[berkeman]

In an effort to get this thread back on track...

I think most of the responses were basically trying to help, and yes the topic of tube amps will generate some controversy. I guess we haven't been able to help much beyond guessing what the term means, based on how tube amps work.

 

[sophiecentaur]

I think of myself as young, yes. I'm 50. If an image of terrorists holding a hostage is considered political here, it suggests there are folks who agree with the terrorists. I think it's just an amusing way to point out that someone is hijacking the thread. So is the spirit here to be both unhelpful and ill-humored?

I think the spirit is to allow a thread to go where it leads. We established fairly early on that there wasn't an answer to the OP so where was the hijack? SO we, helpfully, looked on the net for the answer (no joy) and then we went down memory lane, for the benefit of our retro friends. Perhaps I saw that picture as 'Shouting' in capital letters only more so. Like I said before, you don't see much of that on this forum. There are plenty of places where you do, though.

 

[dlgoff]

Valve distortion is commonly referred to as overdrive, as it is attained by driving the valves in an amplifier at a higher level than can be handled cleanly. Multiple stages of valve gain/clipping can be "cascaded" to produce a thicker and more complex distortion sound. In some modern valve effects, the "dirty" or "gritty" tone is actually achieved not by high voltage, but by running the circuit at voltages that are too low for the circuit components, resulting in greater non-linearity and distortion. These designs are referred to as "starved plate" configurations, and result in an "amp death" sound.

Bold type by me.

http://en.wikipedia.org/wiki/Distortion_%28music%29"

 

[turbo]

That's pretty accurate, Don. The tubes in these designs are running so cold that the filaments don't even glow. They are not acting as gain stages, as in a normal tube amp, but as filters to dirty up the sound of clean op-amps and transistors.

 

[turbo]

Sorry, but this is just ignorant. I really didn't come here to debate the merits of a starved plate design for guitar effect purposes, but if you insist on it, I won't shy away.

You didn't state what you wanted to know about low-voltage tube applications, nor why. My "ignorance" is a matter of opinion. For your information, I have been restoring, repairing and (yes) building tube amps for decades, so I do know a *little* bit about them. I demoed a 5E3 clone at an annual guitar show in Portland. It is now the favorite "house amp" at a pretty decent recording studio.

Plus, I am certainly not anti-SS. BB King and David Hidalgo get wonderful results from SS amps, and when BB is traveling and can't bring along his Gibson Lab-series amps, his contract specifies that the venue will provide an older (SF or BF) Fender Twin Reverb plus a back-up. The Twin is a very loud and clean tube amp with a SS rectifier, so NO sag.