spooki Posted December 13, 2012 Share Posted December 13, 2012 Hello, I'm still amp shopping and found a decent V4x12-C Carvin cabinet for $125. Not knowing anything about ohms I have a concern with the 4 ohm rating. I notice a lot of cabinets are 16 & 8 ohm and some are even switchable. I also still have not found an amp head, so I can share no info on it's future partner. I'm trying to do a budget build and educate myself also. Is there a go and no go direction in the ohms law. Meaning, is 4 ohms more or less universal compared to 16 ohms? Or if mixing them, are you looking for trouble. Any help would deeply be appreciated. I have a small combo amp right now and want to step up to a better sound for my Epi Nighthawk. I did do some reading on reviews for this cabinet and one of the statements was, "why on earth did they even make a 4 ohm cabinet. Unfortunately there was not an answer or reply. Also if it helps, my plan is to pair it up later with a tube head no more than 50 watts and no less than 15. I'm sure the smartest thing would be to get a switchable head. But that might not be the case on my budget build. Thanks again.. Steve Link to comment Share on other sites More sharing options...
RIX Posted December 14, 2012 Share Posted December 14, 2012 I'm replying to your post, because it intrigues me and I'm surprised no one has responded. To start I'm no amp expert, but I do have experience in electronics. As far as why someone would make a 4ohms cabinet it maybe just a matter of power consumption. Lets say you have a 4watt 4ohm amp head and connect a 4ohm 4watt speaker to it you've matched both units and you shouldn't have a problem of overloading the amp head. Another example is a cheap portable radio (here I go dating myself) will have a low wattage low ohm speaker so the radio doesn't need to spend a lot of power to operate. Of course due to the size of the speaker both physical and electrical the sound won't be the best. My other thought is, so you could daisy chain two 4 ohms cabinets together to equal 8ohms total impedance. Idea here maybe that is it better or cheaper to have for example two 12" 4ohm speaker rather than one 24" 8ohm speaker. When you daisy chain two 12" 4ohm speakers together in series you end up with the effect of one 24" 8ohm speaker. Your problem you have to consider now is the wattage of the speakers and the output wattage of your amp head. You run into a problems if you connect a high wattage speaker to an low output wattage amp. The low wattage amp has to work harder to drive the high wattage speaker and so you run the risk of burning out your amp head. On the other hand you also could take two 12" 8ohm speakers and connect them in parallel and end up with a 24" 4ohm effect, but again you have to consider the wattage of the speakers and the output wattage of the amp head. From my personal experience 8ohms is most commonly used in practice amps, which is what I have. My two largest practice amps are both 30watt with 10" 8ohm speakers. I also have a 25watt amp with a 6" speaker, which it sounds okay, but I brought a 10" 8ohm, 30watt speaker that I'm going to make a cabinet for and then connect it to this amp. I've already test connected the speaker to the amp and it sounds pretty good. The fact that the watts don't match shouldn't be a problem, because their no that far off from each other. I'm not sure that I have been of much help and I sure someone in the forum and rip my examples to sherds, but like I said I'm no expert. Link to comment Share on other sites More sharing options...
spooki Posted December 16, 2012 Author Share Posted December 16, 2012 I'm replying to your post, because it intrigues me and I'm surprised no one has responded. To start I'm no amp expert, but I do have experience in electronics. As far as why someone would make a 4ohms cabinet it maybe just a matter of power consumption. Lets say you have a 4watt 4ohm amp head and connect a 4ohm 4watt speaker to it you've matched both units and you shouldn't have a problem of overloading the amp head. Another example is a cheap portable radio (here I go dating myself) will have a low wattage low ohm speaker so the radio doesn't need to spend a lot of power to operate. Of course due to the size of the speaker both physical and electrical the sound won't be the best. My other thought is, so you could daisy chain two 4 ohms cabinets together to equal 8ohms total impedance. Idea here maybe that is it better or cheaper to have for example two 12" 4ohm speaker rather than one 24" 8ohm speaker. When you daisy chain two 12" 4ohm speakers together in series you end up with the effect of one 24" 8ohm speaker. Your problem you have to consider now is the wattage of the speakers and the output wattage of your amp head. You run into a problems if you connect a high wattage speaker to an low output wattage amp. The low wattage amp has to work harder to drive the high wattage speaker and so you run the risk of burning out your amp head. On the other hand you also could take two 12" 8ohm speakers and connect them in parallel and end up with a 24" 4ohm effect, but again you have to consider the wattage of the speakers and the output wattage of the amp head. From my personal experience 8ohms is most commonly used in practice amps, which is what I have. My two largest practice amps are both 30watt with 10" 8ohm speakers. I also have a 25watt amp with a 6" speaker, which it sounds okay, but I brought a 10" 8ohm, 30watt speaker that I'm going to make a cabinet for and then connect it to this amp. I've already test connected the speaker to the amp and it sounds pretty good. The fact that the watts don't match shouldn't be a problem, because their no that far off from each other. I'm not sure that I have been of much help and I sure someone in the forum and rip my examples to sherds, but like I said I'm no expert. Thanks Rix, I also was surprised that I was not receiving replies. Maybe I'm being black-balled. Your info was helpful and I still get confused on the ohms game but decided to skip over the cabinet with the 4 ohms. Shortly after my post a Peavey 4-12MS in good shape with working Celestion 85's in it showed up. 1989 with stereo-mono inputs at 8 and 16 ohms. That solves my problem with the ohm's game and this thing is awesome. Picked it up this morning tested and tried, for $125. Thanks again for your input. Much appreciated. Steve.. Link to comment Share on other sites More sharing options...
Andyroid Posted February 19, 2013 Share Posted February 19, 2013 I would expect it is designed to match up to a solid state amp, as ALL solid state amps are expected to be paired up to a 4ohm cab to achieve their rated wattage. Note, running an amp into less than 4 ohms will get you more wattage than the amp can safely handle and will eventually lead to 'thermal runaway' (flames, dead amp). Most speaker cabs are either 8 or 16 ohms because using two cabs together (ie, in parallel) HALVES the impedance. Two 16ohm cabs = 8ohms. Two 8ohm cabs = 4ohms. Four 16ohm cabs = 4ohms. Cabs with an 'Input' and 'Output' jack socket on the back are ALWAYS wired in parallel. (Tell me if I'm wrong, it has happened once before). You will struggle to wire two cabs up in SERIES, and ADD their impedance's. If you ever plan to pair it up with a second cab, for maybe 8x12", an awesome setup, believe me :-), then you will need to open it up and rewire it to be a 16ohm cab. You will almost certainly have 4x 16ohm speakers in there. So, in pairs wire them in series to make 2x 32ohms, then wire them in parallel to the input jack to bring the total back down to 16ohms. You can then pair it up with another 16ohm cab to present your amp head with 8ohms. Simple. There are other things you should be aware of. Valve amps have output transformers that match their high output impedance up to the speakers low impedance. People often say the 4ohm output sounds warmer/softer than the 16ohm output. So the speaker cab wiring can act as a sort of tone control. There is an electromechanical (just made that word up) phenomenon known as damping. It can be done electrically (by say impedance mismatching)or mechanically (pressing something against the speaker cone). Damping defines how well the amp can get the speaker cones moving and can be affected by how you wire the speakers. You can do your own research into this stuff but most people prefer the sound of speakers wired in series. Having said that, speakers wired in parallel are more bulletproof, safer for the amp. Because if one speaker blows (an becomes an open circuit) there is still a working speaker there for the amp to see. Valve amps MUST have a working speaker connected at ALL TIMES. Have fun, Andy Link to comment Share on other sites More sharing options...
Andyroid Posted February 19, 2013 Share Posted February 19, 2013 Oops, just noticed the message dates and that you've got a different cab anyway. Hope the info's still useful. Andy Link to comment Share on other sites More sharing options...
Starcounter Posted February 19, 2013 Share Posted February 19, 2013 Great info Andy. Answered many questions, even some I didn't know I had. 8) Adam Link to comment Share on other sites More sharing options...
marvar Posted February 19, 2013 Share Posted February 19, 2013 My other thought is, so you could daisy chain two 4 ohms cabinets together to equal 8ohms total impedance. Sorry, this is all wrong- daisey chaining 2 4 ohm cabs will equal a 2 ohm load at the head- Idea here maybe that is it better or cheaper to have for example two 12" 4ohm speaker rather than one 24" 8ohm speaker. When you daisy chain two 12" 4ohm speakers together in series you end up with the effect of one 24" 8ohm speaker. Your problem you have to consider now is the wattage of the speakers and the output wattage of your amp head. You run into a problems if you connect a high wattage speaker to an low output wattage amp. The low wattage amp has to work harder to drive the high wattage speaker and so you run the risk of burning out your amp head. . All this information is completly wrong! speaker wattage rating has absolutly nothing to do with how your amp behaves, and has no adverse effect on your transformers, tubes etc You run into problems when you run a high wattage amp into a lower wattage speaker- the main effect being you blow up the speaker, in turn, blowing your transformers. A speaker is nothing more than a reactive resistor you amp doesn't care what the speakers wattage rating is, it is just looking for the correct ohm load. Link to comment Share on other sites More sharing options...
RIX Posted February 19, 2013 Share Posted February 19, 2013 All this information is completly wrong! speaker wattage rating has absolutly nothing to do with how your amp behaves, and has no adverse effect on your transformers, tubes etc You run into problems when you run a high wattage amp into a lower wattage speaker- the main effect being you blow up the speaker, in turn, blowing your transformers. A speaker is nothing more than a reactive resistor you amp doesn't care what the speakers wattage rating is, it is just looking for the correct ohm load. As I stated in my original reply I'm no amp expert, but if you connect two 4 ohm speakers in series it will equal 8ohm. Perhaps my use of the phase daisy chain was misused. That was the point I was trying to make in my own clumsy way. I'm glad someone is at least reading and replying to the post in the amp section, so the rest of us can learn from their experiences. Link to comment Share on other sites More sharing options...
marvar Posted February 19, 2013 Share Posted February 19, 2013 As I stated in my original reply I'm no amp expert, but if you connect two 4 ohm speakers in series it will equal 8ohm. Perhaps my use of the phase daisy chain was misused. That was the point I was trying to make in my own clumsy way. I'm glad someone is at least reading and replying to the post in the amp section, so the rest of us can learn from their experiences. exception noted! Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.