Kindhornman, I use a 4 LED status display. It's based on an LM quad compartor, backed up by its own stabilized +15V PSU (local). It powers 4 LEDS.
Blue LED is simply an indication of power on (optional).
Green LED informs you that there is a signal present at the output, as small as 100 mV.
Orange LED tells you that you are near the 0 dB VU point, i.e. near the safe maximum.
Red LED warns you that you are dangerously close to what will soon become clipping.
While hardly the point, it also makes for a lovely LED light show, never fails to impress most viewers. I have the schematic but also a well designed PCB, if memory serves with all required GERBER files as well. If you think it might be of interest to you, let me know and I'll send it over as some proof of my belief in what you're going for and of course as a free donation.
However, please note that this is visual indication only, it only tells you what's going on, but does no more than that. Fully scalable, of course, adjust for reference points by adjusting the input voltage divider.
Blue LED is simply an indication of power on (optional).
Green LED informs you that there is a signal present at the output, as small as 100 mV.
Orange LED tells you that you are near the 0 dB VU point, i.e. near the safe maximum.
Red LED warns you that you are dangerously close to what will soon become clipping.
While hardly the point, it also makes for a lovely LED light show, never fails to impress most viewers. I have the schematic but also a well designed PCB, if memory serves with all required GERBER files as well. If you think it might be of interest to you, let me know and I'll send it over as some proof of my belief in what you're going for and of course as a free donation.
However, please note that this is visual indication only, it only tells you what's going on, but does no more than that. Fully scalable, of course, adjust for reference points by adjusting the input voltage divider.
On Nelson's designs for DIYers, I think it's fairly predictable which ones will be favored most.
Locally, Nelson is revered for the simplicity and low cost of his designs. People always say that's what drew them in most, plus of course Nelson's impressive track record.
Most take them as perfection itself, very uncritically. Very few people my mention that some of those designs are very choosy about the speakers they drive, which I must say is also my impression. The few that I tried really shined with my unusually light load speakers, but were not nearly as happy driving AR94, which are not exactly an evil load, but are definitely harder to drive.
Also, there seems to be sort of a movement to evolve them over and above their original form. These I don't know, haven't tried them, so I cannot comment.
Locally, Nelson is revered for the simplicity and low cost of his designs. People always say that's what drew them in most, plus of course Nelson's impressive track record.
Most take them as perfection itself, very uncritically. Very few people my mention that some of those designs are very choosy about the speakers they drive, which I must say is also my impression. The few that I tried really shined with my unusually light load speakers, but were not nearly as happy driving AR94, which are not exactly an evil load, but are definitely harder to drive.
Also, there seems to be sort of a movement to evolve them over and above their original form. These I don't know, haven't tried them, so I cannot comment.
I've had Pass amps driving Infinity 2.5 and 4.5 speakers. They are 4-2ohm loads, have killed several amps, and the Pass amps do much better than most. Some Threshold amps did well to - oh, they were Pass amps too... Some other amps also did well, but my experience is that Pass amps do very well with difficult loads.
" . . . even John Atkinson has no idea why the subjective reviews can be superlative when he sees what should be clearly audible flaws in some pieces over his decades of measurements done alongside most equipment reviews at Stereophile "
Stereophile take a lot of flack for their subjective reviews. However, I respect the overall integrity of the magazine precisely because JA juxtaposes the purple prose with objective measures. Indeed, it is strange that someone can go into raptures over an amp that produces 3 or 4 percent distortion and on the other hand be a little reserved on amplifier that measure superbly.
Unfortunately, I cannot help but feel if something glows, costs way over its functional worth etc, it's going to garner a good reviews.
It reminds me of the old folks and autos
' they just don't make them the way they used to'
To which most of us would reply
'Thank goodness!'
Stereophile take a lot of flack for their subjective reviews. However, I respect the overall integrity of the magazine precisely because JA juxtaposes the purple prose with objective measures. Indeed, it is strange that someone can go into raptures over an amp that produces 3 or 4 percent distortion and on the other hand be a little reserved on amplifier that measure superbly.
Unfortunately, I cannot help but feel if something glows, costs way over its functional worth etc, it's going to garner a good reviews.
It reminds me of the old folks and autos
' they just don't make them the way they used to'
To which most of us would reply
'Thank goodness!'
Hey, I like old cars. You can't beat the sound of a tuned engine on Weber carbs!
Of the stereophile staff only a couple are completely and irrevocably deranged. Others are odd, but at least are up front if they like old altec horns and sub 5-watt tube amps so you know to avoid their reviews if you are not into that stuff.
Of the stereophile staff only a couple are completely and irrevocably deranged. Others are odd, but at least are up front if they like old altec horns and sub 5-watt tube amps so you know to avoid their reviews if you are not into that stuff.
View attachment Behringer - B2031p - Schematic.pdf
has useful limiter.
IIRC Rod Elliot has a distortion indicator that compares power amp output to input.
Dan.
IIRC Rod Elliot has a distortion indicator that compares power amp output to input.
Dan.
Thank all of you for discussing the light idea and dvv for taking it to another level. That would be a nice visual clue. At the same time I was asking if there was a simple way to just limit the input voltage to the amplifier so you couldn't drive it above a set point limit. I guess that is the definition of a limiter then. In live music applications there was always a compressor limiter and these were before the power amps. I guess it isn't as simple as just shunting any power over a set voltage limit.
Well in this case it is a serious question. If you just have digital input you have control at what FS means in terms of power output. If you have an analogue input you cannot prevent someone 'cranking it up'. One might hope that with peak output of 107dB said persons ears would give out first but perfectly valid to discuss the edge cases and IF they can be designed for.
Plan b is make it digital only of course.
Plan b is make it digital only of course.
Yes. To provide an indicator only, is useful for those who are certain that any clipper or soft limiter can be heard, so want to make their own decisions on listening level.
Some secondary limiting that protects the loudspeaker might be advised. It's nice to not clip the output stage.
It's fairly easy to make a clipper that is really benign until it starts to clip. The soft limiters sound better to most ears despite the onset of distortion at lower levels, but they are almost by definition not "audiophile".
Thanks everyone for the comments. Yes 107db should be plenty for us sane people but there is always the crazy consumer who thinks hey this would be great to take outside and have a party and just pushes it up since there is no distortion up to the destructive level, I guess you can't really plan for stupidity but it is what people do. I always stayed away from selling any raw drivers to people with cars since that seemed to be the point at one time, how loud can you get yours even if you couldn't possibly sit in the car and not ruin your ears, they would just blow things up for fun and then send the stuff back to the manufacturer for warranty repairs, not something I wanted to be a part of.
I do like the idea of the lights and really for analog I would think the output voltage of most preamps would be reasonable, but once we get to digital it seems there are no standards for output voltage. One device may be 1 or 2V and another may be 5V output, that must be hard to deal with.
Who said I want to just throw away all the work that others have tried to do in creating great sound circuits, I just want to protect the speakers and amps when the input voltage is unknown and can be excessive.
I do like the idea of the lights and really for analog I would think the output voltage of most preamps would be reasonable, but once we get to digital it seems there are no standards for output voltage. One device may be 1 or 2V and another may be 5V output, that must be hard to deal with.
Who said I want to just throw away all the work that others have tried to do in creating great sound circuits, I just want to protect the speakers and amps when the input voltage is unknown and can be excessive.
obligatory H2G2 quote which seems apt for the car audio crowd as seen by the non-car audio crowd:
"Disaster Area was a plutonium rock band from the Gagrakacka Mind Zones and was generally regarded as not only the loudest rock band in the Galaxy, but also as being the loudest noise of any kind at all. Regular concert goers judged that the best sound balance was usually to be heard from within large concrete bunkers some thirty-seven miles away from the stage, whilst the musicians themselves played their instruments by remote control from within a heavily insulated spaceship which stayed in orbit around the planet - or more frequently around a completely different planet."
"Disaster Area was a plutonium rock band from the Gagrakacka Mind Zones and was generally regarded as not only the loudest rock band in the Galaxy, but also as being the loudest noise of any kind at all. Regular concert goers judged that the best sound balance was usually to be heard from within large concrete bunkers some thirty-seven miles away from the stage, whilst the musicians themselves played their instruments by remote control from within a heavily insulated spaceship which stayed in orbit around the planet - or more frequently around a completely different planet."
The first computer speaker for which I did the electronics was a JBL-branded one for DEC, part of their ill-fated entry into the home computer market. I had thought that stereo audio taper potentiometers didn't track channels very well, so I used linears.
When I started reporting to Rick Weisman, he mentioned that he liked the speakers because it was difficult to drive them into distortion with whatever line-level source he was using. This was not the result of limiters or compressors, just low gain! And there was the curious psychological effect of the linear taper pot.
Other clients and cultures have other preferences. A little subwoofer done for Epson required what I regarded as an absurd amount of gain, and was a serious challenge to achieve adequate signal-to-noise ratio. I had a front end that should have been fine, but for the d.c. flowing in the initially-chosen surface mount resistors, one in particular, which had a truly hideous excess noise index. Replacement with a metal film reduced the noise by about 30 dB!
When I started reporting to Rick Weisman, he mentioned that he liked the speakers because it was difficult to drive them into distortion with whatever line-level source he was using. This was not the result of limiters or compressors, just low gain! And there was the curious psychological effect of the linear taper pot.
Other clients and cultures have other preferences. A little subwoofer done for Epson required what I regarded as an absurd amount of gain, and was a serious challenge to achieve adequate signal-to-noise ratio. I had a front end that should have been fine, but for the d.c. flowing in the initially-chosen surface mount resistors, one in particular, which had a truly hideous excess noise index. Replacement with a metal film reduced the noise by about 30 dB!
and with a compressor in line with the speakers you'll get more sales because they'll "sound really good when you turn them up".
A number of self powered speakers intended for near field monitors in "studios" (I use that work advisedly here) have protection built in, I have seen too often people pushing them too hard (into protection) because "they give me a better picture of the sound".
It is, however, probably the best route to go.
Cheers
Alan
A number of self powered speakers intended for near field monitors in "studios" (I use that work advisedly here) have protection built in, I have seen too often people pushing them too hard (into protection) because "they give me a better picture of the sound".
It is, however, probably the best route to go.
Cheers
Alan
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