Reply by Adrian Tuddenham December 1, 20162016-12-01
whit3rd <whit3rd@gmail.com> wrote:

> On Wednesday, November 30, 2016 at 2:33:11 PM UTC-8, Adrian Tuddenham wrote: > > Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote: > > > Loudspeakers sometimes have hidden surprises. > > > > A while ago I had to design a very high quality pre-amp and equaliser > > system using only E88CC (6922) double-triodes... > > > I found that when I increased the system gain beyond a certain point, > > the whole lot 'took off' into oscillation. ... >> I tracked it down to acoustic feedback into the > > electrodes of the E88CC, which were very rigid but must have had a > > high-Q resonance around 40 Kc/s. > > > > The most puzzling aspect of the whole thing was how a rubbishy > > cardboard-coned ex-television set loudspeaker, squirting noise through a > > few holes drilled in the metal underside of the bench amplifier, could > > possibly have been responding acoustically to a watt or less of signal > > at 40 Kc/s. > > Perhaps the 'equal and opposite' reaction to the cone movement > in the speaker was conducted through the magnet and speaker frame into > the bench and through the amplifier chassis. The voice coil is likely to > accelerate normally at 40 kHz, even if the diaphragm is not following it.
That's a possibility; although I seem to remember that waving my hands around between the bench amplifier and the pre-amp affected the oscillation, so perhaps it was airborn sound but radiated by the metal panel of the bench amplifier. -- ~ Adrian Tuddenham ~ (Remove the ".invalid"s and add ".co.uk" to reply) www.poppyrecords.co.uk
Reply by whit3rd December 1, 20162016-12-01
On Wednesday, November 30, 2016 at 2:33:11 PM UTC-8, Adrian Tuddenham wrote:
> Phil Hobbs <pcdhSpamMeSenseless@electrooptical.net> wrote:
> Loudspeakers sometimes have hidden surprises. > > A while ago I had to design a very high quality pre-amp and equaliser > system using only E88CC (6922) double-triodes...
> I found that when I increased the system gain beyond a certain point, > the whole lot 'took off' into oscillation. ... I tracked it down to acoustic feedback into the > electrodes of the E88CC, which were very rigid but must have had a > high-Q resonance around 40 Kc/s. > > The most puzzling aspect of the whole thing was how a rubbishy > cardboard-coned ex-television set loudspeaker, squirting noise through a > few holes drilled in the metal underside of the bench amplifier, could > possibly have been responding acoustically to a watt or less of signal > at 40 Kc/s.
Perhaps the 'equal and opposite' reaction to the cone movement in the speaker was conducted through the magnet and speaker frame into the bench and through the amplifier chassis. The voice coil is likely to accelerate normally at 40 kHz, even if the diaphragm is not following it.
Reply by boB December 1, 20162016-12-01
On Thu, 1 Dec 2016 00:39:42 -0800 (PST), Phil Allison
<pallison49@gmail.com> wrote:

>boB wrote: > >> >> Multiple output transformers are common place. This 4 channel amp has >> a PFC front end power supply too which is necessary for countries >> requiring CE. >> > > ** More complete bollocks. > >> >> Phil said... >> >> >>** Multi channel class D audio amps can do continuous sine wave power at their lowest rated impedance long as you do not ask all channels to do the same. >> >> >> I was simply responding to Phil's assumption that this 4 channel >> amplifier could onlly supply rated power from one channel at a time as >> far as playing music was concerned. >> > > ** There is NO such wrong assumption from me. > > What I posted above says NOTHING like that. > > You bullshitting ass. > > > >> Assuming that an amplifier is >> going to be used that way is perposterous. >> > > ** You are one preposterous, retarded duck. > > >> >> Just seems a waste of amplifier if what Phil was saying was true. I >> thought he was an expert in this field but I guess not. >> > > ** Bob = boob. > > An illiterate retard with a very nasty attitude. > > > > >.... Phil
boB..... Kisses Phil on the cheek...
Reply by Phil Allison December 1, 20162016-12-01
boB the fuckwit duck  wrote:


> > > > >
> > > >> >> It does work, but it looks like in the past 25 years that I have not > >> >> been in the audio design business in the strictest sense, the method > >> >> of specifying amplifier power has gone more to "music power" where it > >> >> used to be that you could actually get rated output power from an > >> >> amplifier using a sine wave. > >> >> > >> > > >> >** That is not a correct assessment. > >> > >> > >> It was in the USA as far as FTC (Fair Trade Commission) went, at least > >> in the 1970s and 1980s. > >> > > > > > > ** The old duck fool is bullshitting wildly. > > > No BS Phil...
>
** It is nothing but BULLSHIT.
>
> "On May 3, 1974, the Federal Trade Commission (FTC) instated its > Amplifier Rule[12][13] to combat the unrealistic power claims made by > many hi-fi amplifier manufacturers. This rule prescribes continuous > power measurements performed with sine wave signals for advertising > and specifications of amplifiers sold in the US. (See more in the > section Standards at the end of this article). " > > And that is what I was referring to. >
** The FTC test does not require the rated power to be available indefinitely. All the power output figures are SINE WAVE power. You stupid fucking duck. .... Phil
Reply by Phil Allison December 1, 20162016-12-01
boB wrote:

> > Multiple output transformers are common place. This 4 channel amp has > a PFC front end power supply too which is necessary for countries > requiring CE. >
** More complete bollocks.
> > Phil said... > > >>** Multi channel class D audio amps can do continuous sine wave power at their lowest rated impedance long as you do not ask all channels to do the same. > > > I was simply responding to Phil's assumption that this 4 channel > amplifier could onlly supply rated power from one channel at a time as > far as playing music was concerned. >
** There is NO such wrong assumption from me. What I posted above says NOTHING like that. You bullshitting ass.
> Assuming that an amplifier is > going to be used that way is perposterous. >
** You are one preposterous, retarded duck.
> > Just seems a waste of amplifier if what Phil was saying was true. I > thought he was an expert in this field but I guess not. >
** Bob = boob. An illiterate retard with a very nasty attitude. .... Phil
Reply by boB December 1, 20162016-12-01
On Wed, 30 Nov 2016 23:38:22 -0800 (PST), jurb6006@gmail.com wrote:

>>"On May 3, 1974, the Federal Trade Commission (FTC) instated its >Amplifier Rule[12][13] to combat the unrealistic power claims made by >many hi-fi amplifier manufacturers." > >Been there. I was 14 in 1974 but I grew up. The REAL watts, after a time, I started calling "OMWs" which stood for Old Marantz Watts.
I was 20 or so in 1974. I used to call the BS watts, Marketing Watts. Music power and such.
> >But those rules never applied to car amps for example. Who knew you could get 200 watts out of a palm sized EQ/amp that had a 4 amp fuse ? >
Sounds like marketing watts to me !
>Been there. I used the input transformers from Mindblower powered speakers which had a push pull output choke. One output pulled one leg up to 12 V and pushed the other end of the center tapped choke to minus 12 volts. That is 24 volts peak which by IHF standards is a bit over 30 watts RMS into eight ohms. > >I built one for a buddy of mine and told him to be careful with it. He bought car speakers supposedly rated at 90 watts each. Brings it back says one channel is all distorted, and it was. I put the scope on it thinking maybe one of the outputs opened up or whatever but no, the waveform looked good. I brought out a test speaker and it sounded good on that. Then it actually blew the test speaker ! I told him "I warned you". So off to buy more speakers he went. >
I never take speaker power rating literaly to mean that you can drive them with that amount of power on the average... Especially if it's out of its box and at a frequency that vibrates it out of its basket.
>This was after those 200 watt jobs with the 4 amp fuse. These amps of mine took a 15 amp fuse for each channel. I know that seems alot but they fed the transformer directly with zero filtering so the load current had many spikes and valleys which contributed to its demise. Fuses don't like that. > >Later I considered using a Dickson tripler and up the power to nine times what it was and be able to advertise "that tube sound" but after a bit of thought I saw little commercial demand for it. > >But any piece of audio that is for a car or called "professional" is exempt from the FTC and IHF regulation on power output ratings. Phil sees it but the fact is the rating means shit now. Even in home theater equipment, the IHF/FTC ratings (in the US) only apply to the two main front channels. The rest mean shit. >
Forgot about IHF ! Yeah, that too.
>I have seen plenty of them with discrete component mains and a chip driving all the rest of the channels. > >Those "legal" rating only apply to a certain type of equipment and only under certain conditions and only to the two front channels. What goes into cars and bars is completely exempt. > >That's the way it is here, open season on the US consumer. All my shit is 20 years old, I think. Some is older. And my ex brother in law tells me how good these surround systems sound, not to me. > >A bunch of balsa wood cabinets holding speakers that we used to have in $20 radios and one subwoofer to pick the bass up. Bullshit. In fact he is so convinced he gave me his old AR-93Qs that need all the surrounds and the tweeters as well. I should either fix them or sell them. > >But I can't stand surround sound. Too much echo. Too much special effects. In fact I want to watch TV, if I watch TV, in mono.
I use self powered studio monitors pretty much exclusively these days for TV and the computer in the office. Just stereo.
> >They can take their new garbage and put it where it is sure not to get a sunburn. their Win 10, their balsa wood speakers, their cars with more electronics in it than metal, their new TVs, their cable boxes with the cameras (yes, that is not bullshit), their smartphones, all of it. I want a 1967 Chevy. I want an old TV set I can hook my betamax to, you know they were better. I'll take a FM tuner maybe but I want a tuning dial, which drives a tuning capacitor via a string, and hopefully has a weight on it so you can kinda flip it like on those 1970s receivers. > >I am done. I am really done. I mean I do not want to be here. the changes in the world with which I am dismayed will not abate, ever. We got people born into it. One day I will drop fucking dead and I will be thankful for that. > >You can't fix anything, you can't build anything and even if you could most people don't have any money to pay because the banks and rich stole it all. I am eeking out an existence but I see no reason to try. There is no market. > >So I will stick to my old shit and be a little bit happy, and the new generation can deal with it. I wish I could have helped really, and maybe I did. Got the kid, calls me his surrogate Father. Daygo. Starting to understand some things. About why we kill for example. After the Ohio Sate incident he calls me and say he is with me, keep all those motherfuckers out of here, they hate us, why the fuck let them in, and id if it keeps up, kill them all. > >We'll be talking tomorrow I think and I got to get it though his head that the US started this shit and they are pissed just like we would be. But that does not mean to let the in. > >Unless you want interment camps. Australia has them. > >Enough politics. > >Class D amps are great for concerts. The absolute sound quality is simply not that important because things are getting amplified separately. Once all mixed together, proper reproduction is alot more demanding. Separate the issues. > >With amps and politics. (sorry I got into that)
That's OK... There is lots to learn that's for sure. I would rather not have to learn about present day power amp ratings though. Too many changes and not enough time in life to know it all. Heck, not enough brain cells either I suppose. boB
Reply by December 1, 20162016-12-01
>"On May 3, 1974, the Federal Trade Commission (FTC) instated its
Amplifier Rule[12][13] to combat the unrealistic power claims made by many hi-fi amplifier manufacturers." Been there. I was 14 in 1974 but I grew up. The REAL watts, after a time, I started calling "OMWs" which stood for Old Marantz Watts. But those rules never applied to car amps for example. Who knew you could get 200 watts out of a palm sized EQ/amp that had a 4 amp fuse ? Been there. I used the input transformers from Mindblower powered speakers which had a push pull output choke. One output pulled one leg up to 12 V and pushed the other end of the center tapped choke to minus 12 volts. That is 24 volts peak which by IHF standards is a bit over 30 watts RMS into eight ohms. I built one for a buddy of mine and told him to be careful with it. He bought car speakers supposedly rated at 90 watts each. Brings it back says one channel is all distorted, and it was. I put the scope on it thinking maybe one of the outputs opened up or whatever but no, the waveform looked good. I brought out a test speaker and it sounded good on that. Then it actually blew the test speaker ! I told him "I warned you". So off to buy more speakers he went. This was after those 200 watt jobs with the 4 amp fuse. These amps of mine took a 15 amp fuse for each channel. I know that seems alot but they fed the transformer directly with zero filtering so the load current had many spikes and valleys which contributed to its demise. Fuses don't like that. Later I considered using a Dickson tripler and up the power to nine times what it was and be able to advertise "that tube sound" but after a bit of thought I saw little commercial demand for it. But any piece of audio that is for a car or called "professional" is exempt from the FTC and IHF regulation on power output ratings. Phil sees it but the fact is the rating means shit now. Even in home theater equipment, the IHF/FTC ratings (in the US) only apply to the two main front channels. The rest mean shit. I have seen plenty of them with discrete component mains and a chip driving all the rest of the channels. Those "legal" rating only apply to a certain type of equipment and only under certain conditions and only to the two front channels. What goes into cars and bars is completely exempt. That's the way it is here, open season on the US consumer. All my shit is 20 years old, I think. Some is older. And my ex brother in law tells me how good these surround systems sound, not to me. A bunch of balsa wood cabinets holding speakers that we used to have in $20 radios and one subwoofer to pick the bass up. Bullshit. In fact he is so convinced he gave me his old AR-93Qs that need all the surrounds and the tweeters as well. I should either fix them or sell them. But I can't stand surround sound. Too much echo. Too much special effects. In fact I want to watch TV, if I watch TV, in mono. They can take their new garbage and put it where it is sure not to get a sunburn. their Win 10, their balsa wood speakers, their cars with more electronics in it than metal, their new TVs, their cable boxes with the cameras (yes, that is not bullshit), their smartphones, all of it. I want a 1967 Chevy. I want an old TV set I can hook my betamax to, you know they were better. I'll take a FM tuner maybe but I want a tuning dial, which drives a tuning capacitor via a string, and hopefully has a weight on it so you can kinda flip it like on those 1970s receivers. I am done. I am really done. I mean I do not want to be here. the changes in the world with which I am dismayed will not abate, ever. We got people born into it. One day I will drop fucking dead and I will be thankful for that. You can't fix anything, you can't build anything and even if you could most people don't have any money to pay because the banks and rich stole it all. I am eeking out an existence but I see no reason to try. There is no market. So I will stick to my old shit and be a little bit happy, and the new generation can deal with it. I wish I could have helped really, and maybe I did. Got the kid, calls me his surrogate Father. Daygo. Starting to understand some things. About why we kill for example. After the Ohio Sate incident he calls me and say he is with me, keep all those motherfuckers out of here, they hate us, why the fuck let them in, and id if it keeps up, kill them all. We'll be talking tomorrow I think and I got to get it though his head that the US started this shit and they are pissed just like we would be. But that does not mean to let the in. Unless you want interment camps. Australia has them. Enough politics. Class D amps are great for concerts. The absolute sound quality is simply not that important because things are getting amplified separately. Once all mixed together, proper reproduction is alot more demanding. Separate the issues. With amps and politics. (sorry I got into that)
Reply by boB December 1, 20162016-12-01
On Wed, 30 Nov 2016 20:57:40 -0800 (PST), Phil Allison
<pallison49@gmail.com> wrote:

>boB wrote: > >> >> > >> > >> >> No, I'm not using it for audio in this case. I am trying to use it to >> >> imitate mains power with transformer isolatation on the output. >> >> >> > >> >** Multi channel class D audio amps can do continuous sine wave power at their lowest rated impedance long as you do not ask all channels to do the same. >> >> Aha... Is THAT why they do this ? >> > >** The duck fool is totally incorrigible. > >> >> What if the amp is powering the woofers of a big PA ? >> > >** No problem at all, that is the main application for such amplifiers. > > Quack, quack ..... > > > >> >> It's just that the way they are spec'd these days is evidently >> different than it used to be which was by continuous output at one >> frequency or wide band noise. >> > >** The 1/3 noise power figure is continuous and indefinite. > >> >> So what my bitch is that I cannot >> trust the power rating of an audio power amplifier to do what I want >> it to do any more just based on the power rating in watts. >> > >** You absurd "bitch " is YOU want an *audio amplifier* to do something that only an industrial grade amp need to do. > > IOW, you want the earth for sixpence. > > >> I wonder if anybody is doing a bench review of these amps ? >> I'm not sure if I would trust anybody in the audio industry to make >> the kinds of tests I am intersted in though. >> >> > ** None of them is that stupid. > > Quack, quack..... > > > >> >> It does work, but it looks like in the past 25 years that I have not >> >> been in the audio design business in the strictest sense, the method >> >> of specifying amplifier power has gone more to "music power" where it >> >> used to be that you could actually get rated output power from an >> >> amplifier using a sine wave. >> >> >> > >> >** That is not a correct assessment. >> >> >> It was in the USA as far as FTC (Fair Trade Commission) went, at least >> in the 1970s and 1980s. >> > > > ** The old duck fool is bullshitting wildly.
No BS Phil... https://en.wikipedia.org/wiki/Audio_power In part... "On May 3, 1974, the Federal Trade Commission (FTC) instated its Amplifier Rule[12][13] to combat the unrealistic power claims made by many hi-fi amplifier manufacturers. This rule prescribes continuous power measurements performed with sine wave signals for advertising and specifications of amplifiers sold in the US. (See more in the section Standards at the end of this article). " And that is what I was referring to. boB
> > As per ducking usual. > > >> >> >> > >> > But this stubborn, autistic old duck is just not listening. >> >> >> But you're not listening anyway. >> > > >** You are being torn apart, limb from limb, ducky. > > You never knew anything about audio and that will never change. > > Bugger off fool. > > > >.... Phil
Reply by boB December 1, 20162016-12-01
On Wed, 30 Nov 2016 21:00:17 -0800 (PST), jurb6006@gmail.com wrote:

>>"What if the amp is powering the woofers of a big PA ? The woofs would >typically be fed the same signal wouldn't they ? Since the highs >usually don't need as much power as the woofers do, wouldn't it make >more sense to have the other channels rated at a lower power ?" > >To do that requires separate windings on the power transformer. Limiting the power of an amp stage and still feeding it the higher rail voltage saves you nothing.
Multiple output transformers are common place. This 4 channel amp has a PFC front end power supply too which is necessary for countries requiring CE. Phil said...
>>** Multi channel class D audio amps can do continuous sine wave power at their lowest rated impedance long as you do not ask all channels to do the same.
I was simply responding to Phil's assumption that this 4 channel amplifier could onlly supply rated power from one channel at a time as far as playing music was concerned. Assuming that an amplifier is going to be used that way is perposterous. That's basically what he said from what I am reading in that line. Power amps used to be rated so I would not have had to ask these questions.
> >Some powered speakers actually do that, and I have seen bi-amp stand alone power amps that do that is well. But at a cost of course.
> >If they wanted they could make an AC coupled unit for the tweeter off one side of the power for the bass amp. That would unbalance the load but they could handle that. But it would be one quarter the power at the same load impedance and I think they want a bit more than that. Or at least some headroom.
Just seems a waste of amplifier if what Phil was saying was true. I thought he was an expert in this field but I guess not. boB
Reply by December 1, 20162016-12-01
>"What if the amp is powering the woofers of a big PA ? The woofs would
typically be fed the same signal wouldn't they ? Since the highs usually don't need as much power as the woofers do, wouldn't it make more sense to have the other channels rated at a lower power ?" To do that requires separate windings on the power transformer. Limiting the power of an amp stage and still feeding it the higher rail voltage saves you nothing. Some powered speakers actually do that, and I have seen bi-amp stand alone power amps that do that is well. But at a cost of course. If they wanted they could make an AC coupled unit for the tweeter off one side of the power for the bass amp. That would unbalance the load but they could handle that. But it would be one quarter the power at the same load impedance and I think they want a bit more than that. Or at least some headroom.