Boy Thunder Posted April 8, 2008 Share Posted April 8, 2008 OK.. I have to admit I am somewhat ignorant when it comes to ohmage (sp?) and stuff.. Here's the question... I have a 2x10 cab fitted with 100w 16ohm drivers... The cab is rated 250w 8ohm.. one of the drivers is dead so it needs replacing... I have 2 x 10" drivers... they are rated at 150w and 4ohm.... The head that I want to use is an Ashdown MAG 180.. This is rated at 180w RMS and 300w PEAK. Can I put the replacement drivers into the cab and safely run the head or should I find identical rated drivers...? What would the new wattage and ohmage be if I did just do a straight swap? Thanks in advance... even though I feel I'm about to get confused.... Quote Link to comment Share on other sites More sharing options...
bass_ferret Posted April 8, 2008 Share Posted April 8, 2008 Read the wiki for a full explanation of impedence/watts. Quote Link to comment Share on other sites More sharing options...
Boy Thunder Posted April 8, 2008 Author Share Posted April 8, 2008 OK... Thanks I read this [url="http://en.wikipedia.org/wiki/Ohm"]http://en.wikipedia.org/wiki/Ohm[/url] and this [url="http://en.wikipedia.org/wiki/Electrical_impedance"]http://en.wikipedia.org/wiki/Electrical_impedance[/url] and this... [url="http://en.wikipedia.org/wiki/Impedance_matching#Loudspeaker_amplifiers"]http://en.wikipedia.org/wiki/Impedance_mat...aker_amplifiers[/url] But it may as well have been written in Greek.... Can you point me in the direction of something for the layman....? As I am willing to learn... Or say... "Yes, that's fine" or "No, mate... you need to do this..." please.... don't mean to sound ungrateful but the terms I saw are far beyond my knowledge.... Quote Link to comment Share on other sites More sharing options...
WarPig Posted April 8, 2008 Share Posted April 8, 2008 If you used 'I have 2 x 10" drivers... they are rated at 150w and 4ohm....' the overal ratings would be 300w and 2ohm. The 2 ohm would damage the head. If i was you id replace the broken driver with one of the same ratings. Quote Link to comment Share on other sites More sharing options...
Musky Posted April 8, 2008 Share Posted April 8, 2008 Simply put, you shouldn't just do a straight swap with your drivers. Your cab as it stands is wired in parallel - ie the cables from the input jack on your cab go to each speaker individually. Wiring this way means the impedance is split between the two drivers and halved. Which is why your cab is 8 ohm even though it's load with 16 ohm speakers. If you wire up two 4 drivers the same way you'll get a total impedance of 2 ohms, which is below the minimum impedance of you amp. Result = blown amp. However if you wire the drivers in series (ie take the output from one speaker and feed it into the other) you add the total impedence of the drivers. So you'd be back to a 8 ohm cab again. Don't worry about the peak wattage of your amp, it's just quoted to make it sound more impressive. However the cab is wired, wattage is shared equally among drivers with the same impedance. So your cab will be capable of taking 300w (150W per speaker). Incidentally, the MAG puts out 180W into 4 ohms. That means you'll actually be drawing around 120W into an 8 ohm cab. Quote Link to comment Share on other sites More sharing options...
Boy Thunder Posted April 9, 2008 Author Share Posted April 9, 2008 Thanks WarPig and Musky... So... the simple answer is.... no... dont just swap them out...as I could look very upset with a smokin head...But.. I can use them if I wire them in series.... Cool... So I make a single circuit of both drivers... Then I have a 4 ohm cab at 300w... if I understand you right... yeah? Quote Link to comment Share on other sites More sharing options...
bass_ferret Posted April 9, 2008 Share Posted April 9, 2008 Gaining an understanding is much better that just getting answers. When I said wiki I meant the basschat [url="http://wiki.basschat.co.uk/info:amps:impedance_and_wattage"]wiki[/url] Quote Link to comment Share on other sites More sharing options...
Kiwi Posted April 9, 2008 Share Posted April 9, 2008 great article, nice layout too! Quote Link to comment Share on other sites More sharing options...
Musky Posted April 9, 2008 Share Posted April 9, 2008 [quote name='Boy Thunder' post='172790' date='Apr 9 2008, 01:42 AM']So I make a single circuit of both drivers... Then I have a 4 ohm cab at 300w... if I understand you right... yeah?[/quote] Nope... You'll have an 8 ohm cab at 300W. Quote Link to comment Share on other sites More sharing options...
Boy Thunder Posted April 9, 2008 Author Share Posted April 9, 2008 [quote name='bass_ferret' post='172853' date='Apr 9 2008, 08:58 AM']Gaining an understanding is much better that just getting answers. When I said wiki I meant the basschat [url="http://wiki.basschat.co.uk/info:amps:impedance_and_wattage"]wiki[/url][/quote] I agree... gaining an understanding means that in the future I wont need to ask the questions and I am prepared to learn... It's just where I looked made no sense to me at my current knowledge level.... I didn't realise you meant the basschat wiki... I assumed wiki meant... Wikipaedia... I will endeavor to remove my ignorance of this issue as it is an important area to understand, but at the moment the need to have the answer present to me is urgent. Thanks to those that answered the question and from my reply it is obvious that I still didn't get the gist of this issue... However at least I know what I can do and what it will mean... What's next is for me to spend the time learning about the subject properly.. I will read the article next... Thanks again... Quote Link to comment Share on other sites More sharing options...
bass_ferret Posted April 9, 2008 Share Posted April 9, 2008 (edited) Your cab has 2x16 ohm drivers wired in parallel so thats 8 ohms. You want to replace the 16 ohm drivers with 4 ohm drivers so if you wire them in parallel you get a 2 ohm cab and if your amp cant safely drive a 2 ohm cab you are f***ed. If you wire the 4 ohm drivers in series as shown in the wiki article then you will be back to having an 8 ohm cab. The power rating is largely irrelevant. Edited April 9, 2008 by bass_ferret Quote Link to comment Share on other sites More sharing options...
Boy Thunder Posted April 9, 2008 Author Share Posted April 9, 2008 Thanks BF.. That's about where my understanding is at the moment... The BC article is a lot closer to my understanding level and made a lot more sense than the other pages I read... I'm not averse to learning new stuff... but where I was looking made NO sense to me.... and the last thing I wanted to do was blow my amp... I think I have a better understanding now... and I'll use BC wiki before I go elsewhere... Cheers... Quote Link to comment Share on other sites More sharing options...
tauzero Posted April 10, 2008 Share Posted April 10, 2008 [quote name='Boy Thunder' post='172903' date='Apr 9 2008, 10:21 AM']Thanks to those that answered the question and from my reply it is obvious that I still didn't get the gist of this issue... However at least I know what I can do and what it will mean...[/quote] To summarise why series and parallel wiring act as they do (and using the specific case of two identical resistances): In series, the electrons have to push their way first through one resistance, then through another. Therefore the resistances add up. In parallel, the electrons have a choice of resistances to go through. If you've got two equal resistances, half the electrons are going through one and the other half through the other, so it's easier for them to go through - in fact it's twice as easy, so the overall resistance is half of the individual resistances. If you're rewiring your speaker in series, you will have to pay attention to phase. As current passes through a speaker, it either pushes the cone out or pulls it back, depending on the current direction. You don't want one to be going out while the other is moving in, as the combination will cancel out all the hard work each individual speaker is doing. Normally, terminals will be marked - if they're identical speakers, it doesn't really matter if they're marked or not as the terminals will correspond. You want the current to run from the socket to terminal 1 on the first speaker, from there it will emerge at terminal 2, and this should then be connected to terminal 1 on the second speaker. Terminal 2 on the second speaker then goes to the socket. Note that anything marked "Terminal 5" will disappear and never be seen again. Ask Naomi Campbell. Quote Link to comment Share on other sites More sharing options...
Boy Thunder Posted April 12, 2008 Author Share Posted April 12, 2008 Thanks everyone for all the help and advise. It really was useful.. I have re-wired the cab with the 4ohm drivers in series. Popped a Crate Power block through it today and is sounded good to go..... So.. thanks again.... Quote Link to comment Share on other sites More sharing options...
Musky Posted April 12, 2008 Share Posted April 12, 2008 (edited) [quote name='tauzero' post='173891' date='Apr 10 2008, 01:32 PM']Note that anything marked "Terminal 5" will disappear and never be seen again. Ask Naomi Campbell.[/quote] EDIT: In fact to the quotes thread with you! Edited April 13, 2008 by Musky Quote Link to comment Share on other sites More sharing options...
observer Posted December 2, 2011 Share Posted December 2, 2011 If i can join instead of creating new topic. I want to replace drivers in my old 2x10. Want it wired into 8ohm, so can buy 2x16ohm or 2x4 ohm speakers. Any advantage/disadvantage of wiring drivers in serial or paralel mode? Does it affect sound quality, drivers lifespan or antything else? Looks like it easier to buy 4ohm drivers Quote Link to comment Share on other sites More sharing options...
brensabre79 Posted December 2, 2011 Share Posted December 2, 2011 No difference in power handling either way, but (and this applies to the Original Post as well) be careful about just sticking any old speaker into a cab and expecting it to work OK. Cabinets are designed for specific speakers, the size of the cabinet is directly related to the frequency response to bring out the best in the speaker it is designed for. If you put something different in there the sound will be... different - and highly likely to be bad. e.g. the original speakers frequency response tails off below 50Hz, so the cabinet designed with a resonant frequency of 40Hz to compensate. Then you go and stick a speaker in there with a better low frequency response )doesn't tail off until 30Hz) and you get a cab that makes you sound loud boomy when you play one note and virtually inaudible when you play another. (this is a simplified example to get my point across - its more complicated than this in reality!) You might be lucky and get hold of a speaker with a similar response to the original. But if you're replacing speakers in Cabs replace with the same if you can. I found this out the hard way. now I have £200 worh of speakers boxed in my loft Quote Link to comment Share on other sites More sharing options...
flyfisher Posted December 3, 2011 Share Posted December 3, 2011 [quote name='observer' timestamp='1322845136' post='1456634'] Any advantage/disadvantage of wiring drivers in serial or paralel mode? [/quote] If you wire in parallel then failure of one speaker won't mean failure of the whole cab but if in series failure of one speaker would silence the other one. But other than that I don't think there's a lot of difference. The above-mentioned issue of matching the speakers to the cab is the trickiest issue. Quote Link to comment Share on other sites More sharing options...
Bobby K Posted December 7, 2011 Share Posted December 7, 2011 [quote name='brensabre79' timestamp='1322847720' post='1456688'] be careful about just sticking any old speaker into a cab and expecting it to work OK. Cabinets are designed for specific speakers, the size of the cabinet is directly related to the frequency response to bring out the best in the speaker it is designed for. If you put something different in there the sound will be... different - and highly likely to be bad. e.g. the original speakers frequency response tails off below 50Hz, so the cabinet designed with a resonant frequency of 40Hz to compensate. Then you go and stick a speaker in there with a better low frequency response )doesn't tail off until 30Hz) and you get a cab that makes you sound loud boomy when you play one note and virtually inaudible when you play another. (this is a simplified example to get my point across - its more complicated than this in reality!) You might be lucky and get hold of a speaker with a similar response to the original. But if you're replacing speakers in Cabs replace with the same if you can. I found this out the hard way. now I have £200 worh of speakers boxed in my loft [/quote] I hear you mate; I've found out the hard way too it seems.... Just bought a Celestion BN15-400X to go in my Trace 1215 combo. The same as this one: [url="http://basschat.co.uk/uploads/monthly_02_2009/post-2899-1234974845.jpg"]http://basschat.co.uk/uploads/monthly_02_2009/post-2899-1234974845.jpg[/url] The resulting sound was underwhelming, to say the least The cab space in the combo is tiny really, as you can see, so I'm blaming the resulting sound on the fact that this speaker enclosure is far too small for the Celestion to work properly. Or, perhaps my combo's amp section (200 watts) is under-powered for the Celestion?? I dunno.... Maybe somebody could enlighten me...? Mr Fitzmaurice, are you there.....?? I wish I'd done a bit of research first The BN15-400X will be appearing in the for sale section here shortly anyway, for anyone that's interested. Still in as new condition Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted December 7, 2011 Share Posted December 7, 2011 [quote name='Bobby K' timestamp='1323288364' post='1461721'] The resulting sound was underwhelming, to say the least The cab space in the combo is tiny really, as you can see, so I'm blaming the resulting sound on the fact that this speaker enclosure is far too small for the Celestion to work properly. Or, perhaps my combo's amp section (200 watts) is under-powered for the Celestion?? [/quote] That speaker is a bit of an oddball, unusually high Qts for a bass guitar speaker - seems designed to give an old-school midbass 'hump' to the sound but it needs a big box tuned low to stop this being ridiculous. Probably the opposite of the type of driver you want for that Trace unfortunately! The Orange label equiv from Celestion would probably have suited it a lot better, unfortunately they're pretty expensive now. Quote Link to comment Share on other sites More sharing options...
Bobby K Posted December 7, 2011 Share Posted December 7, 2011 Typical innit... I almost bought the orange label one, as they were going cheap in Watford Valves It turned out to be one of those "if it ain't broke don't fix it" things; I've put the original driver back in and it's fine. If truth be known, I was looking to save some weight by putting the neo in. It did make a very noticeable weight reduction too. Lightweight isn't everything though eh. Sound is king! Quote Link to comment Share on other sites More sharing options...
LawrenceH Posted December 7, 2011 Share Posted December 7, 2011 [quote name='Bobby K' timestamp='1323292971' post='1461789'] Typical innit... I almost bought the orange label one, as they were going cheap in Watford Valves It turned out to be one of those "if it ain't broke don't fix it" things; I've put the original driver back in and it's fine. If truth be known, I was looking to save some weight by putting the neo in. It did make a very noticeable weight reduction too. Lightweight isn't everything though eh. Sound is king! [/quote] Doh! Yup I snapped up a couple of neo drivers when I had some cash before the price hikes put them out of reach...sound may be king but my back loves neodymium. I see watford valves still have the 4 ohm version of that orange label as well, tempting me... Quote Link to comment Share on other sites More sharing options...
Bobby K Posted December 7, 2011 Share Posted December 7, 2011 [quote name='LawrenceH' timestamp='1323294364' post='1461811'] sound may be king but my back loves neodymium. I see watford valves still have the 4 ohm version of that orange label as well, tempting me... [/quote] Yes, it does help at the end of the night when you're lugging the gear out Cheers for the input Lawrence Quote Link to comment Share on other sites More sharing options...
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