Mr. Foxen Posted June 5, 2012 Share Posted June 5, 2012 [quote name='Bill Fitzmaurice' timestamp='1338903062' post='1680818'] +1. Most tube amps use a closed circuit switching output jack that shorts the output[b] if there's no speaker plugged in[/b]. That's to prevent damage from what really does bother tubes, which is no load. They're not happy with a load higher than the tap rating either, but a load lower than the tap rating is to a tube as water is to a duck. [/quote] Would more specifically say if there's no lead plugged in, it will be open if a lead is plugged in with no speaker on the end, and that is the trouble place. Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 5, 2012 Share Posted June 5, 2012 (edited) Thanks a lot gents, however i have more dumb questions. Just say an amp (solid state) is 500w into 4 ohms then you buy two cabs one 4 ohms one 8 ohms, according to icastles calculator thing that would be 2.67 ohms. Would that damage the amp? Is the 500w into 4 ohms its minimum? It may not seem like it but this is helping loads even if i don't fully grasp it. i'm getting the basic message. I think! Edited June 5, 2012 by Lord Sausage Quote Link to comment Share on other sites More sharing options...
stingrayPete1977 Posted June 5, 2012 Share Posted June 5, 2012 [quote name='Lord Sausage' timestamp='1338910017' post='1680916'] Thanks a lot gents, however i have more dumb questions. Just say an amp (solid state) is 500w into 4 ohms then you buy two cabs one 4 ohms one 8 ohms, according to icastles calculator thing that would be 2.67 ohms. Would that damage the amp? [b]Is the 500w into 4 ohms its minimum?[/b] It may not seem like it but this is helping loads even if i don't fully grasp it. i'm getting the basic message. I think! [/quote] Yes Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 5, 2012 Share Posted June 5, 2012 [quote name='Lord Sausage' timestamp='1338910017' post='1680916'] Thanks a lot gents, however i have more dumb questions. Just say an amp (solid state) is 500w into 4 ohms then you buy two cabs one 4 ohms one 8 ohms, according to icastles calculator thing that would be 2.67 ohms. Would that damage the amp? Is the 500w into 4 ohms its minimum? It may not seem like it but this is helping loads even if i don't fully grasp it. i'm getting the basic message. I think! [/quote] It will say minimum load 4ohm, which is the important bit. some do down to 2ohm (peavey mostly). The watts part is a separate thing, but since the biggest number will always be the watts at minimum impedance, you can usually assume, but best to know the right thing to look for. Quote Link to comment Share on other sites More sharing options...
chris_b Posted June 5, 2012 Share Posted June 5, 2012 2.67 ohms is not good for an amp with a 4 ohm minimum. 2.67 is less than 4 so you would cause the amp to overheat and power off when thermal protection kicks in. That would probably not damage the amp but you wouldn't be playing for more than a couple of mins at gig levels before TP switches you off. If the amp doesn't have TP then some damage might be caused. Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 5, 2012 Share Posted June 5, 2012 A great man once said " I need TP for my bunghole!" Thanks a lot gents i am a little wiser but still ain't sure what to buy but i am getting much closer. Cheers Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 5, 2012 Share Posted June 5, 2012 OK fellas last question.....I hope! What would you recommend out of the following scenarios:- 1) A 500w into 4 ohms amp into a fender rumble 4x10 which is 500w @ 4ohms or 2) The same amp into a Gk 212 MBE which is 600w @ 8ohms but this gives me the option of adding say another 4x10@ 8ohms at a later date. i.e when got more money. Thanks for your time Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 5, 2012 Share Posted June 5, 2012 The 8 ohm 2x12 might be enough, and you have the option of adding more, although adding a 4x10 is kind of not the way, if you like the sound but want louder, add another the same. If you find the 4ohm 4x10 isn't enough, you are stuck. Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 5, 2012 Share Posted June 5, 2012 Thank you very much kind sir. I'd like to say your help, and other users, has been invaluable especially in giving more info that asked for. I'd kind of drifted away from Basschat for various reasons that i won't go into, however, this thread and the help on it, has reaffirmed what a great place this can be if you talk to the right people. So thanks again everyone! I promised myself i wouldn't cry! Quote Link to comment Share on other sites More sharing options...
icastle Posted June 6, 2012 Share Posted June 6, 2012 [quote name='Lord Sausage' timestamp='1338910017' post='1680916'] Thanks a lot gents, however i have more dumb questions. [/quote] Dumb is not asking and getting it wrong. If you don't know the answers then these are smart questions. Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 6, 2012 Share Posted June 6, 2012 [quote name='icastle' timestamp='1338942218' post='1681590'] Dumb is not asking and getting it wrong. If you don't know the answers then these are smart questions. [/quote] Thanks, as i said it has been a great help. i think i know what i'm gonna buy now with my budget. Quote Link to comment Share on other sites More sharing options...
umph Posted June 6, 2012 Share Posted June 6, 2012 [quote name='Mr. Foxen' timestamp='1338385346' post='1673651'] You can blow 500w rated speakers with a 200w rated amp, because thermal ratings don['t tell you the power it takes to blow a speaker. This is why watt rating have no meaning and thus should be ignored. Clipping does not put out short bursts of DC. This is fact. If you scope it, you do not see a constant flat line above or below 0v which is DC, and you only see a flat top into a purely resistive load, an inductive (such as a speaker) load rounds them off, because the impedance varies with frequency. Basic physics is that if its a waveform, it is alternating, otherwise is isn't a wave, its a flow. Let's see these SPL charts and waterfall plots from the cabs you claim have useable output capacity at 30hz then. [/quote] your amp is broken if it's putting out dc Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 26, 2012 Share Posted June 26, 2012 Sorry for bringing this up yet again! If you are going to put a 500w amp @4 ohms into two 8ohm cabs. Would two 300w handling cabs be enough? Is the 500w split into 250w into each. T^hink i know, I'm just double checking! thanks and sorry! Quote Link to comment Share on other sites More sharing options...
xgsjx Posted June 26, 2012 Share Posted June 26, 2012 Yes, you're correct. Wattage isn't the only thing that blows speakers (it's one of 4 factors), so use your ear & if it sounds bad, adjust to suit. Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 26, 2012 Share Posted June 26, 2012 Watts don't mean anything. Need to know your SPL requirement, since that is the important thing. Quote Link to comment Share on other sites More sharing options...
icastle Posted June 26, 2012 Share Posted June 26, 2012 [quote name='Lord Sausage' timestamp='1340728860' post='1708745'] Sorry for bringing this up yet again! If you are going to put a 500w amp @4 ohms into two 8ohm cabs. Would two 300w handling cabs be enough? Is the 500w split into 250w into each. T^hink i know, I'm just double checking! thanks and sorry! [/quote] Stop apologising The 500W will be split between the two cabs, so a pair of 300W cabs will get 250W each. Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 26, 2012 Share Posted June 26, 2012 [quote name='icastle' timestamp='1340729535' post='1708781'] Stop apologising The 500W will be split between the two cabs, so a pair of 300W cabs will get 250W each. [/quote] Thanks a lot and sorry for keep apologising....sorry Quote Link to comment Share on other sites More sharing options...
Bill Fitzmaurice Posted June 26, 2012 Share Posted June 26, 2012 [quote name='icastle' timestamp='1340729535' post='1708781'] Stop apologising The 500W will be split between the two cabs, so a pair of 300W cabs will get 250W each. [/quote]And since most 300w cabs can only make use of perhaps 150w each you'll still have plenty of amp headroom. Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 26, 2012 Share Posted June 26, 2012 [quote name='Bill Fitzmaurice' timestamp='1340732001' post='1708847'] And since most 300w cabs can only make use of perhaps 150w each you'll still have plenty of amp headroom. [/quote] Can you clarify this? Does that mean of the 250w only 150w get efficiently used? Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 26, 2012 Share Posted June 26, 2012 [quote name='Lord Sausage' timestamp='1340732602' post='1708865'] Can you clarify this? Does that mean of the 250w only 150w get efficiently used? [/quote] Only 150 makes clean sound, any more makes farting noises. The 300w cab rating is the melting power, farting comes around a quarter to a half of that, unless you have fancy speakers (like a woofer/midrange cab). Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 26, 2012 Share Posted June 26, 2012 [quote name='Mr. Foxen' timestamp='1340732931' post='1708878'] Only 150 makes clean sound, any more makes farting noises. The 300w cab rating is the melting power, farting comes around a quarter to a half of that, unless you have fancy speakers (like a woofer/midrange cab). [/quote] So in the situation i'm talking about would i be better getting to 500w cabs then? Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 26, 2012 Share Posted June 26, 2012 [quote name='Lord Sausage' timestamp='1340739354' post='1709027'] So in the situation i'm talking about would i be better getting to 500w cabs then? [/quote] Better ignoring watt rating because they don't mean anything. You 500w cabs might be quieter with the amp output than the 300w ones, so you'd have to put more into them anyway, and they might fart out at 100w whilst the 300w rating ones might fart out at 150w. Need to look at the important info, not the meaningless wattage. Quote Link to comment Share on other sites More sharing options...
Lord Sausage Posted June 26, 2012 Share Posted June 26, 2012 [quote name='Mr. Foxen' timestamp='1340740318' post='1709047'] Better ignoring watt rating because they don't mean anything. You 500w cabs might be quieter with the amp output than the 300w ones, so you'd have to put more into them anyway, and they might fart out at 100w whilst the 300w rating ones might fart out at 150w. Need to look at the important info, not the meaningless wattage. [/quote] Right confused again! What do they put the watt rating on for? and what is the important information? That's a lot of What watts! Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 26, 2012 Share Posted June 26, 2012 [quote name='Lord Sausage' timestamp='1340740920' post='1709064'] Right confused again! What do they put the watt rating on for? and what is the important information? That's a lot of What watts! [/quote] Its the biggest number, so the most impressive. The fact you consider it when thinking of buying an amp is all of the reason. The important information is a maximum SPL chart, and an SPL at a given input voltage chart, so you can see if it goes as high and low, and in the middle as you want with the amount of power you have. The generalised versions of these are the sensitivity rating, which tells you how loud, and the min/max frequency range, but both those are a bit fiddly and only useful for comparing cabs among one manufacturer, since they all fiddle them in different ways. The charts are harder to fiddle without it being obvious. Lots of manufacturers don't supply them, but plenty of people pay money without knowing what they are getting so it works fine for them. Quote Link to comment Share on other sites More sharing options...
xgsjx Posted June 26, 2012 Share Posted June 26, 2012 Watts are the Thermal ratings. That's how much heat the speaker can handle. You're more likely to have a mechanical failure. Quote Link to comment Share on other sites More sharing options...
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