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MultiWay Conventional loudspeakers with crossovers 

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19th March 2011, 04:50 PM  #1 
diyAudio Member
Join Date: Mar 2011

help with options in wiring 4x12 8 ohm cabinet 8 and 16 ohms
Hi everyone,
I just joined. Can someone provide a wiring diagram to be able to split a 4x12 cabinet with 8 ohm speakers such when all 4 speakers are used the impedence equals 8 ohms or have 2 sets of speakers each in series to read 16 ohms each. I believe this can be done with 3 input jacks. 1 jack would control 1 set of 2 speakers in series at 16 ohms and the 2nd jack to control the 2nd set of 2 speakers at 16 ohms and the 3rd jack would control all 4 speakers at 8 ohms wired in series/parallel. I believe one of the jacks would have a 3rd terminal so that when nothing is plugged into it, all 4 speakers would be active at 8 ohms when the plug into the 8 ohm jack. When a plug is inserted into it, it would disconnect part of the wiring allowing for 16 ohm operation with those 2 speakers and 16 ohm on the 3rd jack. Is this doable using certain types of input jacks or using a switch to change from 4 speakers, to 2 speakers at 16 ohms and the other 2 not used. or both sets of 2 speakers each at 16ohms each. I understand the concept of series, parallel and series parallel wiring but am having difficulty trying to have difference wiring options in the same cabinet. Any help would be appreciated. Thanks 
19th March 2011, 05:54 PM  #2  
diyAudio Member

Quote:
Are you doing something like biamping a Marshall 4x12 or some thing like that ? Simon 

19th March 2011, 06:07 PM  #3 
diyAudio Member
Join Date: Mar 2011

Hi Simon,
If bi amping is the ability to use 2 amps with the same speaker cabinet the answer is yes. I want the ability to use 1 amp with 1 set of 2 speakers (16 ohms) and the other using the other 2 speakers (16 ohms) and still have the ability to use the entire cabinnet at 8 ohms. Thanks Jerry 
19th March 2011, 06:50 PM  #4  
diyAudio Member

Quote:
What are the amps ? Are they valve or solid state ? If you wire the 2 seperate pairs together in parallel you should be able to get MORE VOLUME !!!! ie.  Bi amped cabinet 4 Ohms + 4 Ohms &  Single amped cabinet 8 Ohms Simon 

19th March 2011, 07:10 PM  #6 
diyAudio Member
Join Date: Feb 2011

2 speakers in series, gives you the 16 ohm impedance you want.
You would have 2 sets like this. So you can use biamps. If you want them to act as a single 8 ohm load, just paralell connect the 2 of them. 16 ohm is not so good for driving with usual amplifiers. As amplifiers nowdays better like 4 or 8 ohm loads. You could use 2 speakers in paralell, giving you 4 ohms. You would end up with 2 of those, so you can biamp. If you would like to use the cabinet as a single 8 ohm load, You can connect those in series, giving You an 8 ohm load. 
19th March 2011, 07:59 PM  #7 
diyAudio Member
Join Date: Mar 2011

The amps are marshall 2061x which can be switched from 4 to 8 to 16 ohms. The other is a Fender Bandmaster with a Baseman output transformer from Kendricks amplifiers made at 8 ohms (not the typical 4 ohm OT used in bandmasters.
The reason I want 16 ohms is because I was advised that when the OT is set at 16 ohms, it uses all the windings and provides maximum tone, whereas 8 ohms uses less windings than 8 ohms and 4f ohms even less. I understand the different results between series and parallel wiring. I'm just not sure how to accomplish both 16 and 8 ohms at the same time with separate jacks. 
19th March 2011, 09:41 PM  #8  
diyAudio Member

Quote:
OK...The intention of the 4/8/16 switch on the Marshall is to make it easy to match the amplifier to any cabinet setup that it might come across. ie: 1cab, 2cab, not usualy 3cab & 4cab even. I would be surprised if you heard any significant difference in 'tone' between the three settings, as long as they are all used with the correct impedance cabinet. The only difference in 'tone' that is likely (which will infact be more a difference of volume) is if the Marshall is set to 16 Ohms, playing into a 16 Ohm cabinet. Setting the Marshall to 4 Ohms and playing into a 4 Ohm cabinet will be WAY louder than the 16 Ohm setting & cabinet. The other amp with the fixed Fender Bassman replacement transformer is obviously not going to be a perfect match to the other half of the 4x12 at either 4 or 16 Ohms. So there will be a difference in tone (but in fact this is again more a difference of volume). The Fender will play WAY louder into a 4 Ohm cabinet than a 16 Ohm one. So the half of the 4x12 for the Fender could be wired either 4 or 16 Ohms. It could also be wired BOTH 4 and 16 Ohms, with the adition of a 2 way switch, you could then change over impedance/volume and see which you like best. What kind of music do you play is it VERY loud, normal or quiet ? I can advise you also about the cabinet rewiring practicalitys as well. Keeping it simple is always best, as when you have a weirdly wired up cabinet, no one can ever understand how to plug it in except you (especialy after a drink or two !). It doesn't really matter, but just out of interest, I don't know the power of those particular amps, do you know what output valves they have. Marshall EL84 or 34 ? Fender 6L6 ? maybe... Simon P.S  some people feel that series/parallel verses parallel/series wired cabinets 'Sound' different. Personaly I don't think it makes any significant difference, not compared at least to what the guitar is, and what the amp settings, drive/gain & EQ are at. 

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