Follow the links in posts 195 & 196...
I only brought up the half-brain-chicken thing wondering if it were possible for one to write but not read.
I only brought up the half-brain-chicken thing wondering if it were possible for one to write but not read.
Sounds to me that the threadstarter decided to go with the square wheel, after experienced people advising him to go with the round one.
Now he found out that the square wheel wobbles a lot, he wants advice on how to deal with the wobblyness.
Easy solution: go with the round one.
A lot of people have experience using the round wheel, they allready added a bearing to make it run smoother, put in some suspension , maybe just because they were bored.Heck they allready fitted it with a tyre !
By all means, go with the square one.
I expect a new thread in the near future how to fit in a square bearing.
Klaas
Now he found out that the square wheel wobbles a lot, he wants advice on how to deal with the wobblyness.
Easy solution: go with the round one.
A lot of people have experience using the round wheel, they allready added a bearing to make it run smoother, put in some suspension , maybe just because they were bored.Heck they allready fitted it with a tyre !
By all means, go with the square one.
I expect a new thread in the near future how to fit in a square bearing.
Klaas
(I know, I havent been asked...)
I haven't, but I have seen a dog immediately leaved the room as I turned on a linear amp made by me 10 years ago, connected to piezo horns. 🙂
Deep bass can also scare the hell out of a dog, much like a thunderstorm can. Pets should not be subjected to that kind of thing anymore than you'd stick your kid in the backseat of a car and blast the stock 6X9's. You always get your idiots though eh.
I have seen a dog leave the room immediatly after turning on a class d amp as well..... but it was homebrew single ended p2p wired and never seen the likes of a scope 🙂 Smart dog. I knew I'd done well with it when he stopped running for the upper floor.
This brings to mind something...... gasp.... t...... tt.... ttttTOPICAL. (whew). That wasn't easy.
Um, I think a few posts ago I brought up listening to what must have been a commercial class d based home theatre system. The people who had it enjoy the best of the best but obviously they know jack all about audio. That's the system I said you could clearly hear heterodyning on the surrounds? Anyway....
I noticed how the subwoofer kept comming online just when in use. Why is that? Most likely because it's of such poor construction/quality that if left on you'd hear the sucker hissing and humming. The bass from it dirty as my above mentioned homebrew thing, and much less well controlled. You'd hear that noise sticking around when it wasn't in use if they leave it on. So it seems they fake a better amp/powered speaker by shutting it off automatically and constantly. Cheap junk! Now that's for the low frequency subwoofer... so just imagine how bad the receiver sounded.
Proper implementation is more important than what's been getting discussed here so far.. and you're only going to learn that by doing, which you aren't thus far.
I have seen a dog leave the room immediatly after turning on a class d amp as well..... but it was homebrew single ended p2p wired and never seen the likes of a scope 🙂 Smart dog. I knew I'd done well with it when he stopped running for the upper floor.
This brings to mind something...... gasp.... t...... tt.... ttttTOPICAL. (whew). That wasn't easy.
Um, I think a few posts ago I brought up listening to what must have been a commercial class d based home theatre system. The people who had it enjoy the best of the best but obviously they know jack all about audio. That's the system I said you could clearly hear heterodyning on the surrounds? Anyway....
I noticed how the subwoofer kept comming online just when in use. Why is that? Most likely because it's of such poor construction/quality that if left on you'd hear the sucker hissing and humming. The bass from it dirty as my above mentioned homebrew thing, and much less well controlled. You'd hear that noise sticking around when it wasn't in use if they leave it on. So it seems they fake a better amp/powered speaker by shutting it off automatically and constantly. Cheap junk! Now that's for the low frequency subwoofer... so just imagine how bad the receiver sounded.
Proper implementation is more important than what's been getting discussed here so far.. and you're only going to learn that by doing, which you aren't thus far.
lolI've had a subwoofer make me feel motion sick. Can't remember the frequency but we ran something below 20Hz with a lot of power into a respectable sub. Almost immediately I felt sick to my somach. Really wild to feel that subsonic frequency and get sick like that. Never knew I was sensitive to it.
on topic: His question was answered long ago, 1000W, 100dB attentuation of carrier, sub has horrible response at 23.5kHz, speaker cloth blocking more, coils & caps in box blocking the singing of the carrier, if he ever worked the numbers he would be finished. Must not be able to work the numbers.
Oh and I remember a guy talking to me about another subsonic problem. Poeple in an office started complaining they were getting sick at work. After investigation it was found the A/C unit has a subsonic 'rattle' that was making a few people feel sick. Once fix no one got 'sick'.
-SL
on topic: His question was answered long ago, 1000W, 100dB attentuation of carrier, sub has horrible response at 23.5kHz, speaker cloth blocking more, coils & caps in box blocking the singing of the carrier, if he ever worked the numbers he would be finished. Must not be able to work the numbers.
Oh and I remember a guy talking to me about another subsonic problem. Poeple in an office started complaining they were getting sick at work. After investigation it was found the A/C unit has a subsonic 'rattle' that was making a few people feel sick. Once fix no one got 'sick'.
-SL
Hi SpittinLLama,
I think frequencies in the 9 ~ 15 Hz range were being considered for illegal crowd control at one time. Seems the average human has issues here.
It's hard to protest and resist when you've just had an "accident".
-Chris
I think frequencies in the 9 ~ 15 Hz range were being considered for illegal crowd control at one time. Seems the average human has issues here.
It's hard to protest and resist when you've just had an "accident".
-Chris
Tesla was likely the very first to note the type of effects certain frequencies have on the human body and mind, worth looking into, very interesting.
10Hz seems widely regarded as the "fright" note. Maybe that correlates with the brown note.
10Hz seems widely regarded as the "fright" note. Maybe that correlates with the brown note.
My dog used to bark whenever I have a sub turned on. so I had to remove the sub to my basement.
I believe there was a time when people were interested in the use of sonic waves as weapons. Some human organs have an internal frequency of a few hertz.
I believe there was a time when people were interested in the use of sonic waves as weapons. Some human organs have an internal frequency of a few hertz.
http://www.people.vcu.edu/~lenhardt/Pages/Exposure.html
Yes, this could be something. Of course I don't want to build anything that is only tollerable. I want it to be imperceptable.
Yes, this could be something. Of course I don't want to build anything that is only tollerable. I want it to be imperceptable.
http://www.nonoise.org/hearing/criteria/criteria.htm
Says it does not go outside the 20hz to 20khz range, but I'm still going to study it.
Says it does not go outside the 20hz to 20khz range, but I'm still going to study it.
<<<
(I know, I havent been asked...)
I haven't, but I have seen a dog immediately leaved the room as I turned on a linear amp made by me 10 years ago, connected to piezo horns. 🙂
>>>
I've not seen this exactly, but I can envision it. Its exactly the sort of thing I want to avoid.
Seems like there could be lots of sources of spurious sounds in a subwoofer, especially one that is class D.
23.5 khz will be very directional, and it won't propagate far.
Maybe a foam rubber grill cloth?
But mostly I want to find quantifyable limits, and also a precedent for appliances that do admit a low level in that range.
(I know, I havent been asked...)
I haven't, but I have seen a dog immediately leaved the room as I turned on a linear amp made by me 10 years ago, connected to piezo horns. 🙂
>>>
I've not seen this exactly, but I can envision it. Its exactly the sort of thing I want to avoid.
Seems like there could be lots of sources of spurious sounds in a subwoofer, especially one that is class D.
23.5 khz will be very directional, and it won't propagate far.
Maybe a foam rubber grill cloth?
But mostly I want to find quantifyable limits, and also a precedent for appliances that do admit a low level in that range.
If you just want to know if it is imperceptable for you:
Then I would propose to pick a cheap piezo + signal generator and
let it tweet through your living room and simply check, which frequencies you may percept somehow..
I also working on a subwoofer amp. Also 1kW/2Ohms.
I am going for a full bridge coming from +/-55V.
I plan something like 100kHz, because I also want to gain some experience in running it over full range (just to play around).
And because of output filter size. Originally I was also thinking about lower frequencies.
If we ignore (may be) the rabbit of your daughter, then I would also assume something between 20kHz...30kHz could work.
Also I think that such a design is possible with bipolars, at least I guess that some of our SMPS and BJT freaks like Eva could handle. But I am not sure if it is fortunate. For myself I decided that for my amp (even while I was originally considering similar low frequencies as you) I will go for MosFets. From my perspective it is easier. Because:
- We have to handle something like 50A, means you will have to provide several amps base drive current and much higher peaks for proper turn ON and OFF (negative peak required).
- Dead time between upper and lower switch is directly pushing up unpleasant distorsions, that have a similar harmonic spectrum as the well known cross over distorsion in class B amps. So everybody tries to keep it low. Reasonable dead times are below 1% of the period, better 0.1%. At 25kHz this means 0.1% ... 1% of 40us. So you should handle deadtimes of some hundret nano seconds (say: 400ns dead time is already a quite poor design), which is not easy with heavy BJTs. Please be aware that the storage time of BJTs is dramatically increasing by temperature. Means turn OFF delay is increasing and may eat up the dead time and system runs into cross conduction.
- Base drive of upper BJT: Take care if you plan to use a transformer.
This transformer does not only have to transfer the HF signal of 20...30kHz. It has to transfer also the LF frequency modulation, means the trafo will see a LOT of low frequency signal and has to be designed accordingly with respect to core saturation.
I feel this three reasons are good reasons for MosFets here, also at 20kHz...30kHz. But please now do not think that a 1kW class D MOSFET design is a completely trivial thing. Even with MosFets, there is still remaining a good portion of R&D fun.
Then I would propose to pick a cheap piezo + signal generator and
let it tweet through your living room and simply check, which frequencies you may percept somehow..
I also working on a subwoofer amp. Also 1kW/2Ohms.
I am going for a full bridge coming from +/-55V.
I plan something like 100kHz, because I also want to gain some experience in running it over full range (just to play around).
And because of output filter size. Originally I was also thinking about lower frequencies.
If we ignore (may be) the rabbit of your daughter, then I would also assume something between 20kHz...30kHz could work.
Also I think that such a design is possible with bipolars, at least I guess that some of our SMPS and BJT freaks like Eva could handle. But I am not sure if it is fortunate. For myself I decided that for my amp (even while I was originally considering similar low frequencies as you) I will go for MosFets. From my perspective it is easier. Because:
- We have to handle something like 50A, means you will have to provide several amps base drive current and much higher peaks for proper turn ON and OFF (negative peak required).
- Dead time between upper and lower switch is directly pushing up unpleasant distorsions, that have a similar harmonic spectrum as the well known cross over distorsion in class B amps. So everybody tries to keep it low. Reasonable dead times are below 1% of the period, better 0.1%. At 25kHz this means 0.1% ... 1% of 40us. So you should handle deadtimes of some hundret nano seconds (say: 400ns dead time is already a quite poor design), which is not easy with heavy BJTs. Please be aware that the storage time of BJTs is dramatically increasing by temperature. Means turn OFF delay is increasing and may eat up the dead time and system runs into cross conduction.
- Base drive of upper BJT: Take care if you plan to use a transformer.
This transformer does not only have to transfer the HF signal of 20...30kHz. It has to transfer also the LF frequency modulation, means the trafo will see a LOT of low frequency signal and has to be designed accordingly with respect to core saturation.
I feel this three reasons are good reasons for MosFets here, also at 20kHz...30kHz. But please now do not think that a 1kW class D MOSFET design is a completely trivial thing. Even with MosFets, there is still remaining a good portion of R&D fun.
Sorry Choco,
Too meta, let's just focus on the physiological effects right now... and keep this thread cool. The hard practicalities of Class D design won't be an issue until 2046.
😉
Too meta, let's just focus on the physiological effects right now... and keep this thread cool. The hard practicalities of Class D design won't be an issue until 2046.
😉
poobah said:
Poobah?! Still awake? You should be in bed! Or are you recently hanging around in Europe or Asia?
If you are travelling close to GuangZhou, I could invite your for some TsingTao beer.
2046.. You mean zenmaster has still a tough path ahead in class D DIY? Probably, yes. But no matter if Master will get his beast working or not. In any case he will gain some more knowledge, as we always do during DIY.
BTW: My energy thread fell asleep!
OK... now where do we loose the energy if we just have one charged cap and discharge it with zero ohms?
ashok said:
That's " Meltdown" !
It is just about theory! In real life you will always have a finite resistance and a simple to understand loss mechanism. Also a normal copper wire has a simple to calculate resistance. And real caps do have something like an ESR. The fun in that thread is that we loose the energy even with theretically ZERO ohms.
We should not put to much OFFTOPIC here.
Let's better move to:
http://www.diyaudio.com/forums/showthread.php?s=&threadid=85425
<<<<
If you just want to know if it is imperceptable for you:
Then I would propose to pick a cheap piezo + signal generator and
let it tweet through your living room and simply check, which frequencies you may percept somehow..
>>>
I do plan to do this exactly, piezo and signal generator.
Its from having done things like this many years ago that I am suspicious that maybe more can be perceived when it is continuous, than we really know.
I still believe that there are all kinds of appliances where this question must have been raised. So I beleive the info does exist.
If you just want to know if it is imperceptable for you:
Then I would propose to pick a cheap piezo + signal generator and
let it tweet through your living room and simply check, which frequencies you may percept somehow..
>>>
I do plan to do this exactly, piezo and signal generator.
Its from having done things like this many years ago that I am suspicious that maybe more can be perceived when it is continuous, than we really know.
I still believe that there are all kinds of appliances where this question must have been raised. So I beleive the info does exist.
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