Mr Fretbuzz Posted June 24, 2012 Share Posted June 24, 2012 I'm thinking of getting a mag 300 or 600 head but don't understand ohms. Some cabs are 4 and others 8. The head says that minimum inpedence is 4 ohm. What's it all about guys? I'm thinking I might want to get one cab and maybe add another if that's possible or the other alternative is to get a 300 or 600 combo and add to that. How many cabs can you add to a head unit? What ohm do they need to be? How many cabs can you add to a combo and what ohm do they need to be etc I'm going to meditate now...ohm ohm :-D Quote Link to comment Share on other sites More sharing options...
essexbasscat Posted June 24, 2012 Share Posted June 24, 2012 Funny you should be thinking about this right now ........ Quote Link to comment Share on other sites More sharing options...
icastle Posted June 24, 2012 Share Posted June 24, 2012 Right, it's like this... You can add cabs until you hit the minimum impedance figure. Two 8 ohm cabs equal a 4 ohm load. So, using the MAG as an example, you can run two 8 ohm cabs on the amp and you will get the maximum volume that the amp can produce. If you go below 4 ohms (so adding a third cab or using an 8 ohm and a 4 ohm cab at the same time) then you're probably headed for an expensive repair bill. How's that? Quote Link to comment Share on other sites More sharing options...
Mr Fretbuzz Posted June 24, 2012 Author Share Posted June 24, 2012 Ace, thanks a lot. They've brought out a couple of new 4. X 10 cabs..one is 4 ohm and the other 8. Not sure why they would do that .... I guess the 4 ohm is more powerful in one unit and the other is more flexible so you could add say a 15 inch 8 ohm cab? Would it be worth adding a 15 or just get the 4 ohm 4x10 ? Quote Link to comment Share on other sites More sharing options...
icastle Posted June 24, 2012 Share Posted June 24, 2012 [quote name='Mr Fretbuzz' timestamp='1340569976' post='1706458'] Ace, thanks a lot. They've brought out a couple of new 4. X 10 cabs..one is 4 ohm and the other 8. Not sure why they would do that .... I guess the 4 ohm is more powerful in one unit and the other is more flexible so you could add say a 15 inch 8 ohm cab? Would it be worth adding a 15 or just get the 4 ohm 4x10 ? [/quote] This is where planning ahead is going to make the difference. If you think you need the whole 600W on day one and reckon that you can get the sort of sound 'spread' that you like from a single 4x10 then you need to go for that 4 ohm one. Beware though - that'll be 'it' as far as future expansion is concerned. If it's unlikely you'd need the full 600W on day one then I'd go for the 4x10 8 ohm and leave myself a litle expansion space for another cab later, if I decided I needed it. manhandle two cabs about, then that would make sense. If you think that you might only need the full 600W for an occasional gig then Quote Link to comment Share on other sites More sharing options...
Mr. Foxen Posted June 24, 2012 Share Posted June 24, 2012 The blue Ashdown drivers don't have very high excursion, so the 4x10 is very unlikely to handle 600w alone, 300w it might just about be able to do, so best off with 8 ohm one. Quote Link to comment Share on other sites More sharing options...
Rowley Birkin QC Posted June 27, 2012 Share Posted June 27, 2012 Mr Fretbuzz, I used, until recently, a Mag 600 head with a 2x10 & 1x15 Ashdown cabs, both 8 Ohm. Gave me the Flexibility to only use one cab at smaller gigs, but PLENTY of oomph! at larger ones with both. Worked well. If you're lloking for a 600 head I have one for sale. Take a look at the following link. [url="http://basschat.co.uk/topic/179273-fs-ashdown-600-head-evo-ii-with-octaver-compressor-l200/"]http://basschat.co.uk/topic/179273-fs-ashdown-600-head-evo-ii-with-octaver-compressor-l200/[/url] Quote Link to comment Share on other sites More sharing options...
Mr Fretbuzz Posted July 8, 2012 Author Share Posted July 8, 2012 Yay, got 5 numbers in Saturdays lotto..thats £1782 coming my way for a new Amp Quote Link to comment Share on other sites More sharing options...
chrismuzz Posted July 8, 2012 Share Posted July 8, 2012 Bloody hell congratulations mate Don't forget to upload a picture of your new rig when it arrives so we have something to drool over! Quote Link to comment Share on other sites More sharing options...
Doctor J Posted July 8, 2012 Share Posted July 8, 2012 [quote name='icastle' timestamp='1340568800' post='1706435'] Right, it's like this... You can add cabs until you hit the minimum impedance figure. Two 8 ohm cabs equal a 4 ohm load. So, using the MAG as an example, you can run two 8 ohm cabs on the amp and you will get the maximum volume that the amp can produce. If you go below 4 ohms (so adding a third cab or using an 8 ohm and a 4 ohm cab at the same time) then you're probably headed for an expensive repair bill. How's that? [/quote]It's not quite that simple. It all depends on how you connect the cabs to the head. If the cabs are connected in parallel - ie each cabs is plugged into each separate output of your Ashdown amp, then the ohm rating is halved - ie two 8 ohm cabs will result in a resistance of four ohms which is your ultimate goal to get the best out of your amp. However, if you connect in serial - ie the second cab plugged into the first cab which is plugged into the head - then you double the resistance, meaning two 8 ohm cabs will combine to make a 16 ohm load. Quote Link to comment Share on other sites More sharing options...
Mr Fretbuzz Posted July 8, 2012 Author Share Posted July 8, 2012 [quote name='chrismuzz' timestamp='1341753573' post='1723556'] Bloody hell congratulations mate Don't forget to upload a picture of your new rig when it arrives so we have something to drool over! [/quote] Cheers not bad for £1 lucky dip bought on the spur of the moment..one more number and it would have been either 175k or 1.3m, still can't complain eh...I get my Amp :-). Going to get the MAG 300 Evo iii 2x10 combo to start with :-) Quote Link to comment Share on other sites More sharing options...
chrismuzz Posted July 8, 2012 Share Posted July 8, 2012 [quote name='Doctor J' timestamp='1341760611' post='1723658'] It's not quite that simple. It all depends on how you connect the cabs to the head. If the cabs are connected in parallel - ie each cabs is plugged into each separate output of your Ashdown amp, then the ohm rating is halved - ie two 8 ohm cabs will result in a resistance of four ohms which is your ultimate goal to get the best out of your amp. However, if you connect in serial - ie the second cab plugged into the first cab which is plugged into the head - then you double the resistance, meaning two 8 ohm cabs will combine to make a 16 ohm load. [/quote] Never heard this before! Is that just with this particular head or what? Quote Link to comment Share on other sites More sharing options...
Doctor J Posted July 8, 2012 Share Posted July 8, 2012 (edited) [quote name='chrismuzz' timestamp='1341766120' post='1723778'] Never heard this before! Is that just with this particular head or what? [/quote]Ohms law. http://physics.bu.edu/py106/notes/Circuits.html [url="http://www.bcae1.com/spkrmlti.htm"]http://www.bcae1.com/spkrmlti.htm[/url] Edited July 8, 2012 by Doctor J Quote Link to comment Share on other sites More sharing options...
icastle Posted July 8, 2012 Share Posted July 8, 2012 [quote name='Doctor J' timestamp='1341760611' post='1723658'] However, if you connect in serial - ie the second cab plugged into the first cab which is plugged into the head - then you double the resistance, meaning two 8 ohm cabs will combine to make a 16 ohm load. [/quote] Wrong I'm afraid. Unless you have cables specially made to force the cabs to be used in series, this method will still result in the cabs being in parallel. Quote Link to comment Share on other sites More sharing options...
flyfisher Posted July 8, 2012 Share Posted July 8, 2012 Yep, there's a big difference between the physical cable arrangement and the electrical circuit arrangement. Quote Link to comment Share on other sites More sharing options...
thunderider Posted July 10, 2012 Share Posted July 10, 2012 ok so if ur head has a minimum of 8 Ohms use one plug @8ohms....to use both u then have to have 2 16 ohm cabs?? Quote Link to comment Share on other sites More sharing options...
tauzero Posted July 13, 2012 Share Posted July 13, 2012 [quote name='Doctor J' timestamp='1341760611' post='1723658'] However, if you connect in serial - ie the second cab plugged into the first cab which is plugged into the head - then you double the resistance, meaning two 8 ohm cabs will combine to make a 16 ohm load. [/quote] I do hope no-one is misled by this completely inaccurate statement into daisy-chaining two 4 ohm cabs thinking they'll get 8 ohms... Where cabs have two connectors, they will be connected in parallel. So two 8 ohm cabs will combine to make a 4 ohm load. Quote Link to comment Share on other sites More sharing options...
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