my mixer outputs over 9V. I'm now looking into a compressor/limiter since that is how it is handled in recording studios I think.
One can create a fire to test a smoke alarm. Or just not create a fire.
Is this about PA/DJ stuff? Not many use 9V output mixers in HiFi. Also 9V output level coupled to 3V input sensitivity is error by design/choice. My monitor system with hyperfast ADC and telepathic algorithm says that situation is designed to create problems.
Is this about PA/DJ stuff? Not many use 9V output mixers in HiFi. Also 9V output level coupled to 3V input sensitivity is error by design/choice. My monitor system with hyperfast ADC and telepathic algorithm says that situation is designed to create problems.
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no pa or dj here. I have lots of equipment including analog synths. Everything connects to my mixer. The mixer would need to connect the the amp. I need some type of solution to prevent overvoltage going to the amp. This is common in larger recording studios. Not sure about 'hifi' but i'm about keeping my analog signals pure analog, including my analog synths and analog drum machine. I"m willing to build or buy the last piece of the puzzle to get that analog from my synth to the speakers without damaging anything. My ears are not as good as they used to be since i've seen many live shows which led to my interest in building analog synths. I don't trust my hearing to tell if the speakers are clipping. I realize this is not a popular setup and frowned up by 'hifi' enthusiasts at times. Someone even says it is the 'dumbest idea in hifi in DECADES', and I am truly proud of that accomplishment considering how long the hobby has been around.
Adjust gain of the mixers output stage internally and reduce 9V output levels to normal line levels. Solved. At the root. Without adding again extra stuff but by simply taking away the possibility/risk of amplifier damage. This is a 100% remedy for the issue as mentioned in the thread title. You don’t need to protect against what can not occur and your precious analog signals will not be altered/manipulated just like you desire.
However maximum allowable volume is a different matter with regards to loudspeakers and ears. This is not the subject but it is related. Even with for instance 2V line levels that can not damage the power amplifier. We don’t know if your amplifiers are 1W or 1 kW. We used to say the limit was when ears started to bleed but one is better careful as one only gets a set of ears once. If you get assistance from someone with good hearing once you can determine the maximum allowable volume and note that down. Keep it 20% lower and all is good.
However maximum allowable volume is a different matter with regards to loudspeakers and ears. This is not the subject but it is related. Even with for instance 2V line levels that can not damage the power amplifier. We don’t know if your amplifiers are 1W or 1 kW. We used to say the limit was when ears started to bleed but one is better careful as one only gets a set of ears once. If you get assistance from someone with good hearing once you can determine the maximum allowable volume and note that down. Keep it 20% lower and all is good.
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Bob Cordell's soft-clamp circuit from his first book (pp. 368-9), might be one possibility. It's potentiometer adjustable, you can dial the "output voltage must never exceed ±X" setting to whatever voltage X you like. The soft clamp action makes a smoother and more rounded transition zone between not-clamped-at-all and the clamping plateau. Here it is, clamping the top of a sinewave whose amplitude is far too great. Does it increase distortion when the signal voltage peaks are a few hundred millivolts below X volts? Yes it sure does. That's what rounded corners give you.
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Another idea: build your own DIY mixer with standardised signal levels. With all the bells and whistles you want on a mixer (and by omitting unused features).
Challenge. Achievement.
Challenge. Achievement.
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@Mark Johnson wow, I think that is it, thanks! My biggest concern was sending the square into the amp. I would like to implement a peak voltage detector as well, but am keeping that separate for now to keep it simple.
For the peak detector, the closest design I've found to my peak detector is this one which uses op-amps but the ones built into a PIC. I"m using an STM32F373 which also has op-amps, but I was not going to use 64 leds... I have a bluetooth PCB/module done which is sending telemetry data to an iPad or web browser. I can then send all this to the iPad on top of my amp, like McIntosh does with its large displays.
PeakDetector Circuit1
Clip Detector Circuit 1
Clip Detector Circuit 2
I'll check out Bob Cordell's book, thx.
@Mark Johnson which of his 2 books is it? ( Designing Audio Circuits or Systems or Designing Audio Power Amplifiers )
For the peak detector, the closest design I've found to my peak detector is this one which uses op-amps but the ones built into a PIC. I"m using an STM32F373 which also has op-amps, but I was not going to use 64 leds... I have a bluetooth PCB/module done which is sending telemetry data to an iPad or web browser. I can then send all this to the iPad on top of my amp, like McIntosh does with its large displays.
PeakDetector Circuit1
Clip Detector Circuit 1
Clip Detector Circuit 2
I'll check out Bob Cordell's book, thx.
@Mark Johnson which of his 2 books is it? ( Designing Audio Circuits or Systems or Designing Audio Power Amplifiers )
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@Mark Johnson I'm looking at buying Bob's book. I see 2 on Amazon and want to ensure I get the right one. I see his latest has content from his previous book but not sure if the schematic you are referring to appears in it. I think this book will answer many other questions I have too 😉
I also see you mentioned other in past post: "...Six years later, he devotes eight pages (695-703) of the 2nd edition of his book "Small Signal Audio Design" (C 2015) to just..." Douglas Self's 5th edition of "Audio Power Amplifier Design Handbook" (C 2009) says, on page 271:"
THis is interesting as well:
I also see you mentioned other in past post: "...Six years later, he devotes eight pages (695-703) of the 2nd edition of his book "Small Signal Audio Design" (C 2015) to just..." Douglas Self's 5th edition of "Audio Power Amplifier Design Handbook" (C 2009) says, on page 271:"
THis is interesting as well:
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Bob Cordell calls his soft-limiter circuit "Klever Klipper" and it's included in his Power Amp book (1st and 2nd editions). I don't believe he included it in his second book about Audio Circuits and Systems.
You and your circuit design team might decide to modify Bob's design a little bit, to work within the environment of a preamp instead of a power amp.
You and your circuit design team might decide to modify Bob's design a little bit, to work within the environment of a preamp instead of a power amp.
My team and I have discussed this ( me and my choc lab ) and we both think maybe a voltage divider is the best solution for output coming out of my mixer. I think @ItsAllInMyHead suggested that. Since it is not usually an issue with 'normal' pre-amps and hifi equipment, having a device designed just for my mixer kinda makes sense. It sure would make the design much simpler. I'm guessing I just use 1 resistor in series with the output from the mixer, and one to ground. I'm thinking a 10K and 4K7. Does this seem ok?
What about reducing the too high gain of the output stage of the mixer!? In the book Hochpegel Audio Geräte by prof. dr. Heinrich Laut 3rd edition 1983 this is called the “ultra-effizienz Verstärkungsreduktion” method. This was discovered accidentally after a night of too much Schnapps when prof. dr Laut coincidentally found out that the best way to fight a hangover was not to drink too much.
So reduction of the maximum possible output level instead of first amplifying too much and then attenuating. And messing with raising a probably decent low output impedance. If that mixer is opamp based it is a matter of changing 2 resistors according my electro chick lab.
I get the impression I speak an illegible alien language. Well in fact I do 🙂
So reduction of the maximum possible output level instead of first amplifying too much and then attenuating. And messing with raising a probably decent low output impedance. If that mixer is opamp based it is a matter of changing 2 resistors according my electro chick lab.
I get the impression I speak an illegible alien language. Well in fact I do 🙂
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@roboDNA - We need to differentiate what I'd do personally (what I recommend), and what I offered as a solution to meet your stated requirements.
What I recommend is:
If you must have 'something' then my proposed solution to meet your goal (which is easy and allows flexibility should you later decide that this really may not be what you want) is:
You've got some unique requirements, IMO. My preference (and it is just a preference) is that the signal remain unclipped / unclamped. Prevention via attenuation could do that for you with what I'd consider little effort. That's why if I had to meet your goals with your gear, it's the route I'd most likely choose vs. building another circuit.
After re-reading a few of your posts, it seems like not only do you never want the output voltage of the pre-amp to exceed 3V, but that you want to be able to actively adjust it such that you run to nearly 3V at dynamic peaks for certain passages / music, thus why you may want some visual indicator. Still not completely sure... but most importantly ... have fun with it. Designing / incorporating something to meet your own personal need and succeeding will be super-cool, IMO.
All sorts of solutions are out there. You can now experiment and see what works best for your situation. Let us know. I for one, would enjoy seeing a 'Klever Klipper' in use for a pre-amp just as a curiosity. It works marvelously (why would it not) for the "gain clone" amps for which Mr. Cordell was kind enough to share some design options. Mark J then offered boards a group buy some time ago, if I recall.
What I recommend is:
If you must have 'something' then my proposed solution to meet your goal (which is easy and allows flexibility should you later decide that this really may not be what you want) is:
You've got some unique requirements, IMO. My preference (and it is just a preference) is that the signal remain unclipped / unclamped. Prevention via attenuation could do that for you with what I'd consider little effort. That's why if I had to meet your goals with your gear, it's the route I'd most likely choose vs. building another circuit.
After re-reading a few of your posts, it seems like not only do you never want the output voltage of the pre-amp to exceed 3V, but that you want to be able to actively adjust it such that you run to nearly 3V at dynamic peaks for certain passages / music, thus why you may want some visual indicator. Still not completely sure... but most importantly ... have fun with it. Designing / incorporating something to meet your own personal need and succeeding will be super-cool, IMO.
All sorts of solutions are out there. You can now experiment and see what works best for your situation. Let us know. I for one, would enjoy seeing a 'Klever Klipper' in use for a pre-amp just as a curiosity. It works marvelously (why would it not) for the "gain clone" amps for which Mr. Cordell was kind enough to share some design options. Mark J then offered boards a group buy some time ago, if I recall.
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An old post by forum member @Lee Knatta may be illuminating:
Knatta's circuit is noninverting and doesn't include any opamps. If you like, you can adapt his circuit idea to use different DC power supplies instead of +100V and -100V. You can also implement different clamping levels instead of relying upon two 4.7V zener diodes.
Knatta's circuit is noninverting and doesn't include any opamps. If you like, you can adapt his circuit idea to use different DC power supplies instead of +100V and -100V. You can also implement different clamping levels instead of relying upon two 4.7V zener diodes.
@ItsAllInMyHead thanks. I need to take all I've learned since posting my question and make a plan. You are right, I should first try without adding any extra gear in the signal path. I like that idea. I need to understand the mixer better, including how I can ensure the voltage does not exceed 3V using the mixer's faders and vue meter. I suspect the vue meter will be very accurate and be exactly what I need as far as 'voltage peak detector' but without sample/hold. I would just need to adjust the master fader for different styles of audio played. I'll look into how I can SAFELY connect my oscope to the mixer's output to see what the voltage looks like a clean sine at 20khz and 30Hz and I'm guessing that will be the peak no matter what audio I play.
Another option I have is to feed my analog mixer into my focusrite scarlet i2i DAC but I would lose the analog signal I'm working hard to maintain. The DAC will not output more than 3V no matter what I feed it from the mixer. It also has peak detector on input with yellow/red leds.
I'll see how that goes and then look at clip detection circuits again, but I suspect I won't need it. I don't want to play speaker at really high volume, but was doing all this to ensure I was not driving my fancy F5m and speakers at 20% capacity 🙂
I also plan on getting a dB monitor app on my iPad to see if I'm getting 85db at 1meter from the speaker or maybe 2 meters. That is as loud as I want it anyways after I"m done with my experiments.
Funny though, at one point when testing my F5m, I had the mixer fader at 0db, and a cheap pair of re-foamed infinity bookshelf speaker and it sounded amazing and really thumping those things. ( roland TR-8S drum machine demo tracks ) I did not hear any distortion. Perhaps it was a result of having the F5m at only about 400mV bias. I wont' be doing THAT again... hahahahaha!
Another option I have is to feed my analog mixer into my focusrite scarlet i2i DAC but I would lose the analog signal I'm working hard to maintain. The DAC will not output more than 3V no matter what I feed it from the mixer. It also has peak detector on input with yellow/red leds.
I'll see how that goes and then look at clip detection circuits again, but I suspect I won't need it. I don't want to play speaker at really high volume, but was doing all this to ensure I was not driving my fancy F5m and speakers at 20% capacity 🙂
I also plan on getting a dB monitor app on my iPad to see if I'm getting 85db at 1meter from the speaker or maybe 2 meters. That is as loud as I want it anyways after I"m done with my experiments.
Funny though, at one point when testing my F5m, I had the mixer fader at 0db, and a cheap pair of re-foamed infinity bookshelf speaker and it sounded amazing and really thumping those things. ( roland TR-8S drum machine demo tracks ) I did not hear any distortion. Perhaps it was a result of having the F5m at only about 400mV bias. I wont' be doing THAT again... hahahahaha!
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