icastle Posted May 30, 2012 Share Posted May 30, 2012 (edited) [quote name='xgsjx' timestamp='1338404584' post='1674139'] Now that I do need to get involved in. I've just started learning about gardening this past couple of weeks. Mother nature's had it for the past 4 1/2 years & I'm slooooowwwwly taking it back. It was like the Amazon, now it's just a jungle. There's rhubarb in there, there's some weird exotic plants (probably weeds) & there's loads of my old favourite.... Brambles! I bought a strimmer & a lawnmower & now have something that resembles a patch of grass & I'm working on what could once maybe have been a vegetable garden!!! The neighbour has one of these "Bushcutter" things. It's like a petrol strimmer with a thick 3 pronged blade. He went into my jungle & broke it within 5 minutes! Oil peeing everywhere! I've been slowly working on a corner with large shears & heavy duty loppers (that can cut a 2" branch) & slowly working my way in. I can almost get to the 2nd shed! [/quote] You don't need the Gardening thread, you need a new one entitled 'Jungle Warfare' The gardening thread is possibly the longest running thread on BC without a cross word being spoken... a little vegetable oasis It's [url="http://basschat.co.uk/topic/127962-any-gardeners-on-here-then/page__st__500__p__1648302__hl__any%20gardeners%20on%20here"]here[/url] BTW. Edited May 30, 2012 by icastle Quote Link to comment Share on other sites More sharing options...
GregBass Posted May 30, 2012 Share Posted May 30, 2012 [quote name='dincz' timestamp='1338404929' post='1674145'] The polarity and the direction of current flow don't alternate so it's not AC - just pulsating DC. [/quote] Of course, if it's a 9V battery, it could actually be a rectangular wave of 4.5V amplitude with a DC offset of 4.5V Quote Link to comment Share on other sites More sharing options...
xgsjx Posted May 30, 2012 Share Posted May 30, 2012 [quote name='icastle' timestamp='1338405447' post='1674156'] You don't need the Gardening thread, you need a new one entitled 'Jungle Warfare' The gardening thread is possibly the longest running thread on BC [b]without a cross word being spoken[/b]... a little vegetable oasis It's [url="http://basschat.co.uk/topic/127962-any-gardeners-on-here-then/page__st__500__p__1648302__hl__any%20gardeners%20on%20here"]here[/url] BTW. [/quote] That's until I start contributing of course! Quote Link to comment Share on other sites More sharing options...
Musky Posted May 30, 2012 Share Posted May 30, 2012 [quote name='GregBass' timestamp='1338404576' post='1674138'] Hmm. Note that we can't see the x-axis scale. [/quote] It's in the bit at the bottom of the graph marked 'time scale' [quote]That horizontal portion could be 10ns or 10 minutes. Are you saying that if it's 10 minutes, we are not seeing DC? [/quote] Yes. [quote]At which point does it stop being a blip on a waveform and start being DC?[/quote] At the point does it stops alternating between positive and negative and stops being a wave. [quote]Just asking - because if you connect a scope to a battery via an open switch, close the switch for a while then open it again you see a square wave (try it). Does this mean the battery does not produce a direct voltage? Or would you have to be selective about which bit of the waveform you look at?[/quote] I'd expect to see a pulsating current when you switch something on and off. Not a square wave though, just something that looks like one. [quote]BTW, I did acknowledge that I had misread your statement. [/quote] Missed that, sorry. Quote Link to comment Share on other sites More sharing options...
icastle Posted May 30, 2012 Share Posted May 30, 2012 [quote name='xgsjx' timestamp='1338406149' post='1674172'] That's until I start contributing of course! [/quote] We've done organic DIY plant food and greenfly killer already. Don't make me resort to home brew napalm... Quote Link to comment Share on other sites More sharing options...
xgsjx Posted May 30, 2012 Share Posted May 30, 2012 [quote name='icastle' timestamp='1338406606' post='1674185'] We've done organic DIY plant food and greenfly killer already. Don't make me resort to home brew napalm... [/quote] Now that would be useful in my "garden". The neighbour suggested a flamethrower & a couple of grenades. Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted May 30, 2012 Share Posted May 30, 2012 [quote name='GregBass' timestamp='1338404576' post='1674138'] Hmm. Note that we can't see the x-axis scale. That horizontal portion could be 10ns or 10 minutes. Are you saying that if it's 10 minutes, we are not seeing DC? At which point does it stop being a blip on a waveform and start being DC? Just asking - because if you connect a scope to a battery via an open switch, close the switch for a while then open it again you see a square wave (try it). Does this mean the battery does not produce a direct voltage? Or would you have to be selective about which bit of the waveform you look at? BTW, I did acknowledge that I had misread your statement. [/quote] [quote name='dincz' timestamp='1338404929' post='1674145'] The polarity and the direction of current flow don't alternate so it's not AC - just pulsating DC. [/quote] It has already been said a bunch of times, that if you put an inductive or capacitive load on the output, then you don't get the flat bit. a capacitor will block DC, but pass AC (up to a point given its specification). This is what makes the difference between resistance and impedance, and a speaker is not a purely resistive load. an if you connect a battery to one, the cone just moves to a point and stays there, and that is it. Quote Link to comment Share on other sites More sharing options...
CraigPlaysBass Posted May 30, 2012 Share Posted May 30, 2012 This is great guys, don't stop, I feel like I'm learning loads! (No sarcasm intended). So... Could someone please explain to me clearly what the difference is between DC and the clipped waveform? I get that they look the same on the graph but aren't, why? I expect it was somewhere in the thread but there were lots of angry rebuttals in-between... Quote Link to comment Share on other sites More sharing options...
charic Posted May 30, 2012 Share Posted May 30, 2012 I liked the bit where qualifications were thrown in :-D Also the answer is ofcourse... 42 Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted May 30, 2012 Share Posted May 30, 2012 [quote name='CraigPlaysBass' timestamp='1338409734' post='1674271'] This is great guys, don't stop, I feel like I'm learning loads! (No sarcasm intended). So... Could someone please explain to me clearly what the difference is between DC and the clipped waveform? I get that they look the same on the graph but aren't, why? I expect it was somewhere in the thread but there were lots of angry rebuttals in-between... [/quote] DC isn't a waveform, its current flowing. Kind of like the difference between the sea doing tides and waves, and a river flowing. The waves are higher harmonics and the tides are the fundamental (which is sort of irrelevant to previous sentence, but its sort of a neat way of putting it). And if you pass a clipped/square wave into an electrical component other than a perfect resistor, the graph won't be square any more, it will round off according to the inductive or capacitive qualities of that component, namely a speaker (obviously some components do other stuff, but couldn't think of a term to cover both resistors, capacitors and things that have resistive or capacitive effect). Basically, whatever shape the wave is, if its a wave, then it is AC. Quote Link to comment Share on other sites More sharing options...
GregBass Posted May 30, 2012 Share Posted May 30, 2012 [quote name='charic' timestamp='1338410273' post='1674283'] I liked the bit where qualifications were thrown in :-D Also the answer is ofcourse... 42 [/quote] 42? That's soooo yesterday Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted May 30, 2012 Share Posted May 30, 2012 [quote name='CraigPlaysBass' timestamp='1338409734' post='1674271'] Could someone please explain to me clearly what the difference is between DC and the clipped waveform? [/quote]DC is constant polarity and has no phase. AC has phase, and with each passage of 180 degrees of phase polarity is reversed. Quote Link to comment Share on other sites More sharing options...
CraigPlaysBass Posted May 30, 2012 Share Posted May 30, 2012 I don't think I'm going to bother asking any more questions in this thread. Quote Link to comment Share on other sites More sharing options...
chris_b Posted May 30, 2012 Share Posted May 30, 2012 [quote name='CraigPlaysBass' timestamp='1338409734' post='1674271'] ....I feel like I'm learning loads.... [/quote] ....and you need to know all of this in order to buy a bass amp and cab! Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted May 30, 2012 Share Posted May 30, 2012 [quote name='chris_b' timestamp='1338414557' post='1674390'] ....and you need to know all of this in order to buy a bass amp and cab! [/quote] The right bass amp and cab, more specifically. Although people can get away with the wrong ones quite well. Quote Link to comment Share on other sites More sharing options...
aldude Posted May 31, 2012 Share Posted May 31, 2012 Interesting chat on here about DC and AC which I haven't noticed before as I never read this thread. Unfortunately I believe that what is and isn't DC is rather subjective, as it all depends on the length of time you are talking about. If you're talking about a clipping waveform, like the one posted on page 2, then it's not DC as far as I understand. It's a waveform, and to consider whether it's got DC you need to consider it over several cycle periods, i.e. several up/down cycles. Over say 5 or so, the waveform is perfectly symmetrical (if that is that the right word) around zero voltage so there is actually no DC in there at all, ever. In other words, the negative bit is basically the same as the positive bit, so no DC. If you're considering just the "flat bit", ok strictly speaking it's DC but then every waveform, ever, including a pure sinusoid, has some DC in it if you're considering only a small part of the waveform, as it's not symmetrical (or whatever the right word is) about zero voltage. This is obviously silly and any electronic engineer knows not to consider DC across a period of time that is anything less than the period of the waveform, because it would give a result that is misleading. For the record it's quite hard to see visually if a waveform has DC over a period of time if it's complex, some integration will be required. If the integration shows a positive or negative result, instead of a zero, then that result is the DC value. Hopefully this image will give a good example: here is a waveform with a pure sinusoid component and a DC component. This actually has lots of DC - because the negative bit is not the same as the positive bit ... in fact there is no negative bit! The DC value is 8 volts. [url="http://people.sinclair.edu/nickreeder/eet155/PageArt/waveSinePlusDC.gif"]http://people.sinclair.edu/nickreeder/eet155/PageArt/waveSinePlusDC.gif[/url] I think there has been some confusion as to the language originally used - perhaps a lot of the irrelevant discussion could have been avoided if the term "DC" was replaced with something else ("flat bit" will do ). Quote Link to comment Share on other sites More sharing options...
dincz Posted May 31, 2012 Share Posted May 31, 2012 Both AC and DC current can vary but if the current alternates in direction then it's alternating current (AC). Quote Link to comment Share on other sites More sharing options...
JTUK Posted May 31, 2012 Share Posted May 31, 2012 hmmm..... OP not been back lately..??? Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted May 31, 2012 Share Posted May 31, 2012 [quote name='aldude' timestamp='1338458486' post='1674779'] I think there has been some confusion as to the language originally used - perhaps a lot of the irrelevant discussion could have been avoided if the term "DC" was replaced with something else ("flat bit" will do ). [/quote] The important wrong bit was the idea that it can damage speakers. And the justification that it does so because it is DC is the bit that makes no sense anyway. Quote Link to comment Share on other sites More sharing options...
Big_Stu Posted May 31, 2012 Share Posted May 31, 2012 [quote name='Lozz196' timestamp='1338370722' post='1673313'] Mmmmmm, a can of worms to be opened, methinks. Everyone has their own opinions[/quote] Any chance you can now use your powers to PM me the winning numbers for this week's lottery? Quote Link to comment Share on other sites More sharing options...
Lozz196 Posted May 31, 2012 Share Posted May 31, 2012 [quote name='Big_Stu' timestamp='1338481330' post='1675254'] Any chance you can now use your powers to PM me the winning numbers for this week's lottery? [/quote] Only if you deposit half the winning funds in my account, Stu - in advance Quote Link to comment Share on other sites More sharing options...
EssentialTension Posted June 3, 2012 Share Posted June 3, 2012 [quote name='CraigPlaysBass' timestamp='1338409734' post='1674271'] ... I feel like I'm learning loads! ... [/quote] I can't tell whether I'm learning loads or being led up the gardening path. Quote Link to comment Share on other sites More sharing options...
icastle Posted June 3, 2012 Share Posted June 3, 2012 [quote name='EssentialTension' timestamp='1338744736' post='1678768'] I can't tell whether I'm learning loads or being led up the gardening path. [/quote] BassChat - For All Your Fungal Needs... Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 4, 2012 Share Posted June 4, 2012 this is entertaining but confusing when you know nowt about all this tech stuff. Advanced music theory easy, watts, rms etc.....clueless. i'm looking to buy new stuff too. Can someone explain in laymans speak please. Does it matter if the amp is more powerful than the speakers. Quote Link to comment Share on other sites More sharing options...
stingrayPete1977 Posted June 4, 2012 Share Posted June 4, 2012 [quote name='Lord Sausage' timestamp='1338802455' post='1679298'] this is entertaining but confusing when you know nowt about all this tech stuff. Advanced music theory easy, watts, rms etc.....clueless. i'm looking to buy new stuff too. Can someone explain in laymans speak please. Does it matter if the amp is more powerful than the speakers. [/quote] OK here is the laymans terms, I am one and this is how I see it but the others will be back to baffle you with electronic wizardry and have a debate about it Im sure! I have a Morris Minor (realy ) it was designed for about 28bhp yet you can have a bigger engine like mine with about 39bhp or much more without upgrading the brakes and tyres etc, If you think of the car as the speaker cabs and the engine as the amp then I could drive it all day long without revving it up much and keep it below 20bhp which would be fine, I could drive it hard all the time until something broke but in reality I can drive it within a safe manner and exploit the extra power within reason once I have the feel of when its pushing it too hard (farting speaker constantly etc). Quote Link to comment Share on other sites More sharing options...
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