How to find the peak decibel gain of the highest gain channel of a high gain amp?

[teemuk]

How about quantifying the depth of distortion available by referring the clipping voltage back to the input?

Or use the good old input sensitivity rating?

[thinkingchicken]

How about quantifying the depth of distortion available by referring the clipping voltage back to the input?

Or use the good old input sensitivity rating?

In the schematic of MXR Distortion +, how did we get the 200 dB gain from it?

[teemuk]

We don't.

200 was quoted as approximate voltage amplification ratio/factor, (I assume) calculated from the feedback ratio of the non-inverting opamp according to basic electronics schoolbook rules*:

(1M/4K7)+1=213.77

But it's an incorrect figure because one also needs to divide it by two because of 10k/10k resistive attenuator, so we actually get about 106.9

*I have excluded the reactive elements for simplicity; in practice the gain ratio is frequency dependent: The capacitive reactance, "impedance", of the 47nF cap in the feedback circuit increases at low frequencies decreasing gain and forming a hi-pass filter. There are other RC filters in the circuit too but a good approximation of peak voltage gain figure is 106.9.

Converted to dB this is only about 40 dB. But if we think about that we only need about 3 millivolts of input to get 300 mV output and those diodes to begin to clipping distort the signal it's a pretty ample figure. Especially since we consider about 20 millivolts as nominal input from pickup (plenty of clipping distortion) and at initial picking transients the amplitude may rise up to one or two volts (hell a lot of clipping distortion).

[thinkingchicken]

We don't.

200 was quoted as approximate voltage amplification ratio/factor, (I assume) calculated from the feedback ratio of the non-inverting opamp according to basic electronics schoolbook rules*:

(1M/4K7)+1=213.77

But it's an incorrect figure because one also needs to divide it by two because of 10k/10k resistive attenuator, so we actually get about 106.9

*I have excluded the reactive elements for simplicity; in practice the gain ratio is frequency dependent: The capacitive reactance, "impedance", of the 47nF cap in the feedback circuit increases at low frequencies decreasing gain and forming a hi-pass filter. There are other RC filters in the circuit too but a good approximation of peak voltage gain figure is 106.9.

Converted to dB this is only about 40 dB. But if we think about that we only need about 3 millivolts of input to get 300 mV output and those diodes to begin to clipping distort the signal it's a pretty ample figure. Especially since we consider about 20 millivolts as nominal input from pickup (plenty of clipping distortion) and at initial picking transients the amplitude may rise up to one or two volts (hell a lot of clipping distortion).

Then, we can somehow calculate the peak gain decibel by looking at schematics. Is it possible to get the same 115 dB with the gain knob of red mode OD2 channel of Marshall JVM410H at maximum from a Marshall JVM410 preamp schematic? Did the 115 dB come only from the red mode OD2 channel gain stage alone or is it actually a product of the whole preamp gain stages? According to the original statement, only the gain knob of the highest gain channel is on max. But the Dumble amp is different though, as he said not only the gain knob of the highest channel is on max but everything is on max.

Below is the schematic of Marshall JVM410 preamp.

marshall_jvm410preampschem.pdf_1.png

So, distorted sounds from an open loop opamp with 200 decibel gain literally sound just like the oscillating distortion pedals that I've posted earlier?

[wpaulvogel]

I’m still not understanding the importance of the 115dB gain figure. Tell me if I’m wrong but unless the output remains clean and sinus, the gain diminishes once clipping occurs and to achieve the 115dB of gain the input voltage must be very low. The low input voltage is below what a typical guitar pickup output voltage produces and therefore the signal clips as it passes through the stages and the gain really isn’t that high anymore. To use a pedal to boost the signal to really high levels before the amplifier also creates the same situation and would make the amplifier hard to adjust to any level of control. I find this with adjusting boost pedals to high levels. Also when the clipping occurs because of the high levels of gain the noise floor is significantly raised because it’s level begins low and is easily amplified whereas the fundamental signal is clipping and gains no more amplitude.

[R.G.]

I’m still not understanding the importance of the 115dB gain figure. Tell me if I’m wrong but unless the output remains clean and sinus, the gain diminishes once clipping occurs and to achieve the 115dB of gain the input voltage must be very low. The low input voltage is below what a typical guitar pickup output voltage produces [...]

I think we may be wasting our time here. The OP has had several accurate and consistent explanations, here and at TGP, and still hasn't budged off getting to 115db, understanding db as a way of saying "gain", or getting "db gain" from schematics. I think it's possible that the OP may be after something entirely different and unstated. An even farther out and unlikely possibility is that the OP is really a subtle troll or a question bot. Probably not, but stranger things have happened.

[thinkingchicken]

I’m still not understanding the importance of the 115dB gain figure. Tell me if I’m wrong but unless the output remains clean and sinus, the gain diminishes once clipping occurs and to achieve the 115dB of gain the input voltage must be very low. The low input voltage is below what a typical guitar pickup output voltage produces [...]

I think we may be wasting our time here. The OP has had several accurate and consistent explanations, here and at TGP, and still hasn't budged off getting to 115db, understanding db as a way of saying "gain", or getting "db gain" from schematics. I think it's possible that the OP may be after something entirely different and unstated. An even farther out and unlikely possibility is that the OP is really a subtle troll or a question bot. Probably not, but stranger things have happened.

It doesn't matter if it is 115 dB, it could be 115 dB or more but what's more important is the decibel gain must be beyond 115 dB. I don't understand why people called my questions as trolling or even a question bot.

I'm not after something entirely different or what not. As we have discussed already, we can get decibel gain more than 140 dB from solid-state devices such as open loop opamp but I still didn't listen to how is it sound.

[teemuk]

Then build it. Breadboard and 20 minutes. Granted to get your questions satisfied better and faster than trolling the forums.

[thinkingchicken]

Then build it. Breadboard and 20 minutes. Granted to get your questions satisfied better and faster than trolling the forums.

But I'm not an amp builder that's why I asked my question here. I think some people think I'm trying to insinuate that solid-state amps or distortion pedals are better than tube based devices just because they can generate higher decibel gain. No. I have zero experience in building amps and pedals, hence those questions. Not to mention, people said solid-state devices such as those open loop opamp can generate higher decibel gain but without any example like audios, videos, etc.

For some weird reasons, some people can be offended by mere questions by someone who have no clue at all how electronics work.

[R.G.]

But I'm not an amp builder that's why I asked my question here. I think some people think I'm trying to insinuate that solid-state amps or distortion pedals are better than tube based devices just because they can generate higher decibel gain. No. I have zero experience in building amps and pedals, hence those questions. Not to mention, people said solid-state devices such as those open loop opamp can generate higher decibel gain but without any example like audios, videos, etc.

For some weird reasons, some people can be offended by mere questions by someone who have no clue at all how electronics work.

Aaaaaand that's another possibility. If, as you say, you have no clue how electronics work, you're not likely to be able to understand the answers.

I don't mean this to be negative, but there is a basis of knowledge needed before anyone can understand answers, even simplified ones, to the questions they ask. We've been telling you, as simply as we can, the answers to your questions, but the answers don't seem to be satisfying your internal questions. If you have zero experience in building amps or pedals, and no training (even self training counts!) in electronics, you're not going to be able to understand the answers. Here are some analogies:
A person who has never driven a car wonders why there is special training needed for driving in a Formula 1 racer.
A person who has never gotten beyond algebra wonders how to solve partial differential equations.
A person who has never studied meteorology wonders why weather forecasters get it wrong so much of the time.

There is this concept pervading the internet that a few questions to a forum can make someone understand complex things without going through the underlying training and study that the experts have done. This is one reason I suggested you go read about Dunning-Kruger. People who don't know even the basics in some area of knowledge are further hampered by not knowing how much they don't know about the subject.

Let's do some particulars.

But I'm not an amp builder that's why I asked my question here.

A more appropriate question would then be "I have no electronics experience. How do I learn about building amps?" This very question has been asked here many times, and answered with very helpful and extended answers. People here are willing to help you learn, when you recognize where you need to start.

I think some people think I'm trying to insinuate that solid-state amps or distortion pedals are better than tube based devices just because they can generate higher decibel gain.

There have been long, heated "wars" over whether tube or solid state is better for amps. Some of these wars have been verbally vicious. People remember things like that, and are unintentionally sensitive to them restarting. You have effectively walked into a temporarily quiet battlefield.

I have zero experience in building amps and pedals, hence those questions. Not to mention, people said solid-state devices such as those open loop opamp can generate higher decibel gain but without any example like audios, videos, etc.

Having zero experience (and training, from the format of the questions and responses to the answers) means you can't understand the answers, probably.
And "people" didn't say solid state devices can generate higher "decibel gain", I did, at least on this forum. Well, OK, probably me among others that said much the same thing. Not everything on the net can be reduced to somebody, somewhere, long ago, in a web of fog and mirrors said something vague.
And a video or audio is not going to help you understand that. A youtube video explaining gain (and other complex topics) will more likely leave you with a sense that you ..think.. you understand it, rather than imparting real knowledge. Sorry to be blunt, but youtube is there to make money and collect information on watchers, not to really help you out.
What doesn't seem to have gotten across is that the device, solid state or tube does not matter. There are problems with gain, in and of itself, which make the pursuit of higher and higher gains very difficult and/or impractical. Worse, I haven't seen any explanation from you about the origins of your questions. You're not giving us much to go on to help you.

For some weird reasons, some people can be offended by mere questions by someone who have no clue at all how electronics work.

It's not that there are weird reasons, and it's probably not that the "some people" are offended. It's much more likely that the people you're asking, here at least, have been trying to help others on line for twenty years or more, and they've seen a lot of all kinds of raw beginners, really clueless people who will never understand, and active trolls trying to muddy things up for their own juvenile purposes. That can and does lead to what might be described as "help fatigue". With experience in what is arguably an expert forum, over time people learn what does and does not lead to real help dispensed to people who need it. That leaves them less inclined to spend a lot of time on people (or trolls, or bots, all of which have happened) that don't seem to be receiving the help. Again, sorry to be blunt, but this is factual. If you meant me, I'm not offended. Just sad that it's not helping you. As well as watchful for some of the things you might be as well as just a beginner.

I really wish I could help more, but you're going to have to ask lower-level questions and use them as a basis to build on.

[wpaulvogel]

The reason I don’t understand your interest in exceeding this level of gain (115 or 140) is because in real world scenarios using a typical output guitar pickup, the signal level into the amplifier is already too high for this level of gain because clipping occurring and reducing gain.

[wpaulvogel]

How to find the peak decibel gain of high gain amplifiers? You don’t have an education level with substantial understanding of the concepts or mathematical experience needed to calculate.

[romberg]

The reason I don’t understand your interest in exceeding this level of gain (115 or 140) is because in real world scenarios using a typical output guitar pickup, the signal level into the amplifier is already too high for this level of gain because clipping occurring and reducing gain.

This is a very important point. At a certain level of amplification (gain) the signal will clip. This is not considered a bad thing as most guitar players like the way this sounds. So, as you add gain you keep pushing the guitar's signal into this upper wall. But there is also something else going on.

Riding along with a guitar's signal is another signal. It is background noise. It is produced by the electronics in the guitar itself. There is not much one can do to eliminate this noise short of cooling the guitar and cable to absolute zero. Normally it is much much weaker than the output of a guitar's pickups. So, it is not very noticeable. But then gain is added...

At low amounts of gain the guitar's signal may be say 100db louder than the background noise. So, it does not compete much with the guitar's signal. Now a bunch of gain is applied. Both the guitar's signal and the noise are amplified. And the guitar signal starts to clip. The guitar's signal is not getting any louder but the noise is. The range between the noise and the guitar signal is being compressed. So, now the guitar's signal may be only 12db louder than the background noise. You still don't hear the noise much as long as you keep playing. But when you stop playing the noise is very bothersome. Thus many high gain amps will include noise gates that mute the amplifier when the guitar signal stops.

If the gain is increased even more then the noise itself will start clipping. It is now just as loud as the guitar. And at this point no one can probably tell the two signals apart. It also probably does not matter what the guitar signal is because the noise will more or less drown it out. This is why you don't see guitar amps with say a 1000db of gain. It is pointless to increase the gain beyond a certain limit. My guess is that limit is very close to the gains reported by circuit simulation at the beginning of this thread.

Mike

[wpaulvogel]

I already stated this in an earlier post along with others also stating this.

[thinkingchicken]

But I'm not an amp builder that's why I asked my question here. I think some people think I'm trying to insinuate that solid-state amps or distortion pedals are better than tube based devices just because they can generate higher decibel gain. No. I have zero experience in building amps and pedals, hence those questions. Not to mention, people said solid-state devices such as those open loop opamp can generate higher decibel gain but without any example like audios, videos, etc.

For some weird reasons, some people can be offended by mere questions by someone who have no clue at all how electronics work.

Aaaaaand that's another possibility. If, as you say, you have no clue how electronics work, you're not likely to be able to understand the answers.

I don't mean this to be negative, but there is a basis of knowledge needed before anyone can understand answers, even simplified ones, to the questions they ask. We've been telling you, as simply as we can, the answers to your questions, but the answers don't seem to be satisfying your internal questions. If you have zero experience in building amps or pedals, and no training (even self training counts!) in electronics, you're not going to be able to understand the answers. Here are some analogies:
A person who has never driven a car wonders why there is special training needed for driving in a Formula 1 racer.
A person who has never gotten beyond algebra wonders how to solve partial differential equations.
A person who has never studied meteorology wonders why weather forecasters get it wrong so much of the time.

There is this concept pervading the internet that a few questions to a forum can make someone understand complex things without going through the underlying training and study that the experts have done. This is one reason I suggested you go read about Dunning-Kruger. People who don't know even the basics in some area of knowledge are further hampered by not knowing how much they don't know about the subject.

Let's do some particulars.

But I'm not an amp builder that's why I asked my question here.

A more appropriate question would then be "I have no electronics experience. How do I learn about building amps?" This very question has been asked here many times, and answered with very helpful and extended answers. People here are willing to help you learn, when you recognize where you need to start.

I think some people think I'm trying to insinuate that solid-state amps or distortion pedals are better than tube based devices just because they can generate higher decibel gain.

There have been long, heated "wars" over whether tube or solid state is better for amps. Some of these wars have been verbally vicious. People remember things like that, and are unintentionally sensitive to them restarting. You have effectively walked into a temporarily quiet battlefield.

I have zero experience in building amps and pedals, hence those questions. Not to mention, people said solid-state devices such as those open loop opamp can generate higher decibel gain but without any example like audios, videos, etc.

Having zero experience (and training, from the format of the questions and responses to the answers) means you can't understand the answers, probably.
And "people" didn't say solid state devices can generate higher "decibel gain", I did, at least on this forum. Well, OK, probably me among others that said much the same thing. Not everything on the net can be reduced to somebody, somewhere, long ago, in a web of fog and mirrors said something vague.
And a video or audio is not going to help you understand that. A youtube video explaining gain (and other complex topics) will more likely leave you with a sense that you ..think.. you understand it, rather than imparting real knowledge. Sorry to be blunt, but youtube is there to make money and collect information on watchers, not to really help you out.
What doesn't seem to have gotten across is that the device, solid state or tube does not matter. There are problems with gain, in and of itself, which make the pursuit of higher and higher gains very difficult and/or impractical. Worse, I haven't seen any explanation from you about the origins of your questions. You're not giving us much to go on to help you.

For some weird reasons, some people can be offended by mere questions by someone who have no clue at all how electronics work.

It's not that there are weird reasons, and it's probably not that the "some people" are offended. It's much more likely that the people you're asking, here at least, have been trying to help others on line for twenty years or more, and they've seen a lot of all kinds of raw beginners, really clueless people who will never understand, and active trolls trying to muddy things up for their own juvenile purposes. That can and does lead to what might be described as "help fatigue". With experience in what is arguably an expert forum, over time people learn what does and does not lead to real help dispensed to people who need it. That leaves them less inclined to spend a lot of time on people (or trolls, or bots, all of which have happened) that don't seem to be receiving the help. Again, sorry to be blunt, but this is factual. If you meant me, I'm not offended. Just sad that it's not helping you. As well as watchful for some of the things you might be as well as just a beginner.

I really wish I could help more, but you're going to have to ask lower-level questions and use them as a basis to build on.

So you're insisting that I'm an actually a person who have experiences in building amps and pedals. Cool, can't help with that but it's fine. It's up to you.

When it comes to these stuff relating to "oh the Marshall JVM410H have more gain than this amp or that pedal so it is more suitable to play heavy music than this and that", blah, blah, etc. But most demos showing Marshall JVM410 especially on Youtube even with the gain maxed on the highest gain channel which is the OD2 it is not that unbearable to be honest compared to the feedback oscillating noises that the pedals produced in my previous shared videos.

As we have discussed previously, an open loop op amp have more gain than the maxed out highest gain channel of Marshall JVM410. So if someone tried to experiment with an open loop op amp by making it into the form of a solid-state amp, the end product will be just a noise generator? Correct?