GregBass

I bought a 97 Warwick Standard Corvette from Jigster as backup for my old Rick. The Rick now sits in its case - that Corvette has the best neck I have ever played.

[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

Will you be resurrecting the 100W PA amp too? My band used on in a rehearsal this week with a pair of 1x12 cabs and it sounded superb!

[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 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] Any chance you can bring that lot round to my place and sort out my garden? It's gone a bit wild since I started posting on this thread

[quote name='Musky' timestamp='1338404009' post='1674126'] You'll note I said "The [b]definition[/b] of DC is completely opposed to that of an AC waveform". Please notice the bold bit - picking and choosing which bits to look at often leads to confusion. Once again - picking and choosing which bits to look at often leads to confusion. If it's a wave, it's not DC. An authoratative link for you - [url="http://www.excelsior-audio.com/Publications/Square_Waves_&_DC_Content.pdf"]http://www.excelsior..._DC_Content.pdf[/url] [/quote] 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 name='xgsjx' timestamp='1338403715' post='1674121'] I actually snotted! For that, you're immortalised! [/quote] There should be a Like option for this

Anyway, I withdraw my original comments. I bow to Dr Foxens superior knowledge. There is no need to ensure your speakers can handle the power from your amplifier. I bow to BF's superior knowledge. A section of a voltage trace that remains for a period of time at the same voltage is not DC.

[quote name='Bill Fitzmaurice' timestamp='1338403063' post='1674106'] Well, if you're going to give expert advise the first requirement is that you be an expert. My credentials as such are a matter of public record. I also have a personal rule that I'm here to teach those wishing to learn, not argue with those who don't. As you clearly have no desire to learn, only a penchant to argue that which you don't comprehend, with you I am done. [/quote] My credentials are almost acceptable too, Bill. HNC Electronics & Computer Engineering, BA(Hons) first class Electronics & Computer Engineering. Go ahead - teach me.

[quote name='GregBass' timestamp='1338403002' post='1674103'] DC is not "opposed" to AC in any way. If you want to "oppose" an AC, you need to take the original waveform and invert it. [/quote] Oops - misread your statement. Sorry.

[quote name='Musky' timestamp='1338401334' post='1674055'] If you're talking about a wave that's absolutely correct. The definition of DC is completely opposed to that of an AC waveform, no matter what it looks like. Had you looked for that authoratative link to DC voltages you might have found the physics that does apply. It doesn't look like what you're suggesting. [/quote] Both of your statements are wrong on many counts (sorry to go back to the theory, but I have to challenge this). DC is not "opposed" to AC in any way. If you want to "oppose" an AC, you need to take the original waveform and invert it. On your second point, read this carefully. Look at the trace to which I put the link earlier in this thread - the picture of the scope at the right-hand side of the article. Now take two fingers and cover up the bits at the left and right where the voltage value is rising then falling. Look only at the bit in the middle that's horizontal. Now, in this portion the physics applies, and DC looks exactly like that. OK? That was my point. For a portion of a clipped waveform, the trace is DC. I was not trying to say it's all DC. Just that bit. What happens in the rest of the trace is outside what I was talking about.

[quote name='stingrayPete1977' timestamp='1338399126' post='1673999'] What's all the electronics talk about? The op wanted advice on basses and amps not the Maplins catalog! [/quote] Good question. I posted what I felt was reasionable advice, but a couple of "experts" decided to rip into what I said. I responded. Things got silly.

[quote name='Bill Fitzmaurice' timestamp='1338398272' post='1673978'] No. [/quote] Wow Bill - so if you have a trace that's completely flat at a voltage other than 0, its not a direct voltage? Maybe physics doesnt apply in your universe.

To repeat a post I made earlier .... Just .... WOW

[quote name='dincz' timestamp='1338396686' post='1673946'] I've got no way of doing that at the monent, but I'd expect to see what others have seen: [/quote] I wouldnt bother. Accurate theory doesn'y win over dogma, Im afraid.

[quote name='bassickman' timestamp='1338396608' post='1673944'] The £5k budget is for amp and bass. I'm thinking maybe Fender jazz deluxe 5 with mark bass little mark tube 500 and a mark bass 4 x 10. Or maybe a genz benz shuttle and a vanderkley 4 x 10 or......... a genz benz with a bergantino 4 x10. Thoughts? I've been to bass Direct all day today and I have only warmed to this gear. However, obviously I didn't try every bass in there. Maybe a bass modelled on a j-bass with better components would be an option. [/quote] I saw someone using a Markbass setup a couple of weeks ago, and it sounded pretty decent to me. (Waits for someone with advanced electronics knowledge to tell me I didn't see it, and even if I did it sounded bad). That sounds like a good setup for what you are aiming to do.

[quote name='dincz' timestamp='1338396234' post='1673940'] But you could say the same for an ac waveform. If you take a sufficiently short portion of the peak of the waveform, it would look like DC as well. It might be relevant if your notes are only a few microseconds long - but then they wouldn't be notes. [/quote] Jeez this becoming hard work. If you look at the link I posted, that waveform was clipped for maybe 60% of its period in each half cycle. Now you may class that as negligible, but I would reckon its **almost** noticeable as a distortion of the expected waveform. Of course, if the clipping is not noticeable then theres probably no issue.

[quote name='BOD2' timestamp='1338389002' post='1673743'] No, a "flat waveform" is not a direct voltage - it's a square wave. A direct voltage, if displayed on a scope, would be a continuous straight line above (or below - but NOT both) the zero line on the scope. If you apply a direct voltage to a speaker (not generally a good idea) the cone will push out and stay out (or it will pull back and stay back). It won't make any noise as the cone needs to move backward AND forwards to create air pressure which creates the sound. [/quote] I think you may have missed the bit where I said "for that short period while the line is flat". If you ignore the rest of the waveform, for that short time there is DC applied across the speaker. For that short period, the speaker is pushed (or pulled) and held in a particular position. There's no sound generated, but there may be a bit of heat. This, as you say, is not a good idea - and that was actually my initial point.

[quote name='chris_b' timestamp='1338387766' post='1673709'] If you're playing Gospel, get a 5 string bass, a 410 or 212 cab, a 500 watt amp with a good DI and some flight cases. I think your brain would be better off full of bass lessons than this other stuff! [/quote] Indeed.

[quote name='charic' timestamp='1338387286' post='1673701'] I did electronics as part of my course and it never lined up with what you've said. You're basically coming across as comparing apples and pears, ok it's not apples and oranges but you should stick to apples [/quote] See my post immediately above yours - doesn't that show clearly that clipping is flattening of the peak of the wave? And isn't a flat voltage waveform actually a direct voltage?

Try taking a look at the waveform shown on the scope here: http://en.wikipedia.org/wiki/Clipping_%28audio%29 The tops and bottom of each excursion is flat. Now I could find you an authoritative link to direct voltages, but are you prepared to accept that they are basically voltages of a constant value (that would be flat when shown on a scope)? If so, then surely for that small period when the peak is cut off during clipping, the output is DC?

[quote name='Mr. Foxen' timestamp='1338386163' post='1673668'] This aprt is why it needs correcting every time someone decides to start retelling it. [/quote] Indeed. Maybe you should start with the standard curriculum of most electronics and electrical engineering degree courses )

[quote name='Bill Fitzmaurice' timestamp='1338385955' post='1673665'] It does not. DC does not alternate between positive and negative. That's flawed waveform analysis. The difference between a sine wave and square wave is the harmonic content. A sine wave has none, a square wave has all the harmionics of the fundamental occuring at the same voltage swing as the fundamental. If that's the case they're incorrect as well. I doubt Celestion would make such a grievious error, knowing that the tone of a guitar is pretty much predicated on clipping not only the amp but the driver as well. This document is the source of the myth of underpowering. If readers all paid attention to the key phrase 'high frequency components' the myth might not have arisen. But like all myths it grew with each retelling. [url="http://www.jblpro.com/pub/technote/lowpower.pdf"]http://www.jblpro.co...te/lowpower.pdf[/url] And as to why cliiping has no effect whatsoever on woofers, not only does the added harmonic content of a clipped signal not increase the maximum voltage swing, the majority of the added harmonic content is filtered out by the inductlve and capacitive reactance of the voice coil. [/quote] Bill - what does happen to a sine wave when it clips then? Lets say an amplifier with +/- 10V supplies and an amplification of 10 is fed with an input sine wave of +/- 2V, what will the output be (let's neglect losses etc to make it simple)?

[quote name='Bill Fitzmaurice' timestamp='1338385013' post='1673645'] You misunderstood. [/quote] Indeed I did - sorry for any confusion

[quote name='Mr. Foxen' timestamp='1338382649' post='1673591'] Its ok to use any amp with any speaker if you aren't an idiot about it. I've had one speaker develop a voice coil run in all the time I've been playing really loud bassy detuned music, and that was likely to do with storage conditions. Clipping doesn't cause DC, and doesn't upset bass drivers. I run my amps in clipping all of the time. Pretty much no commercial bass cabinets go as low as 30hz, and it isn't a useful frequency for bass guitar anyway. There are various benefits to valves, and a bunch of them are down to clipping. And a bunch of the others are down to the properties of the output transformer, in particular its ability to filter out extremely low frequencies. [/quote] So you haven't blown your speakers while not power matching them - good. Just to complete the picture, the power handling of the speakers in my rig is currently double what the amp can kick out at full blast. Guess what - I haven't blown any of the speakers either. Does that actually prove anything? As a general rule, I would say it's a decent idea to make sure your speakers can handle the power you intend to kick out of the amplifier. The simplest way to do this is to look at the power ratings, and make sure that the amp is not going to be chucking out more than the speakers are rated to handle. As a sort of rule of thumb, I hardly think that's contentious. Clipping is EXACTLY putting DC in short bursts across the speaker. Think of the theory. Consider a sine wave. When it clips the top of the waveform goes flat - that's basic waveform analysis. A flat waveform is a short burst of DC, that's basic electronics. In fact, the Fane technical department describe it as precisely that when they explain that over pushing the amp is more likely to damage speakers than driving them too hard. I have a nice little Hartke 4x10 which goes down to 30Hz. My 1x18 EV sub does too. That's two out of two. Not bad considering virtually none do, eh? Maybe I'm just lucky. It's actually very useful for the heavy rock I play, mostly without house PAs to play through. I didn't mention anything about the benefits of valves, so I fail to understand why you are using that criticise my input to the discussion.