Bass Cabinet Speaker Wiring

[DAVID WARD]

I have an 8 ohm 15" bass cabinet and have made a twin 10" wired in series (which makes it 16 ohm) and want to connect the two to my Behringer bass head. It works ok but I read that I should really have two equal resistance cabs connected for best results. If I wire the twin in parrallel it produces 4 ohms which, together with the 15" is too low resistance for the amp. Can I wire parrallel and just stick a resistance on each speaker to produce an 8 ohms cabinet ?

[PeteMcK]

'It works ok ' - then leave it as it is; putting resistance in series only wastes power, unless that resistance is another driver...

[sparkless]

It is not suggested that you run speakers in series. No two speakers will be exactly identical, even if they are the same model from the same manufacturer. This means that they will act slightly different from each other when presented with the same input signal. When wired in series, these differences will cause distortion in the form of back EMF.
You can however run both coils of a DVC speaker in series. The cone movement for both coils will be identical, and will not cause distortion problems. This is the formula to calculate the impedance of speakers in series.

http://www.diyaudioandvideo.com/FAQ/Wiring/

[Inductor]

From what I understand (and please DAVID try to follow me and post exact measure for Rvc for each speaker, if you know it and/or make&model), let's assume that for a typical 8 ohm speaker you have an Re=6 ohm or min.imp. of 7 ohm. Now you put the 2x10" in parallel = 3/3.5 ohm and with the 8 ohm-15" in series you get about 9/10 ohm what is just fine (waiting confirmation with the right measures from speakers) for the 8 ohm head. Since the 15" has different parameters from the 10"s try having them in 2 separate cabinets or divide. Have in mind that you are not expressing the function of each speaker, like one can have a better bass and another more distortion problems at the same level, etc, etc.

[Moondog55]

What inductor said

I wouldn't put the single 15 in the same cabinet ( although I have done so ) but running the 10s in parallel then connect in series to the 15 to give a nominal 12R load is OK

Regards
Ted

[DAVID WARD]

Thanks for response guys - for information the 15" is in a separate cabinet.

I should go out and buy one but like many of us, I have been trying to pursue perfection - gut wrenching bass in a cabinet I can carry without causing a hernia. The 2X10 was reasonably successful as a practice cab, but then I got clever and tried a 4 X 8 which was rubbish - sounded no better than 2 X 10 and was very lop sided heavy - so I will probably just put my existing 15" in a handier sized cabinet.

The only success I would claim which may interest others is making a cabinet half the weight of 3/4" MDF. This was achieved by framing each panel with 20mm strip and finishing with 6mm MDF externally and 3mm MDF internally, the gap then filled with expanding foam. Then screw panels together as normal. It is very strong and seems to resonate well. Happy to give more details to anyone interested.

David

[Moondog55]

My daughter is a bass player, I made her a cab with 2 * 15 plus 2 * 12 wired series /parallel for a nominal 6R load and IT wasn't loud or deep enough for her.
If I do it again I'll use 4 * 18s BUT don't try and move it by yourself.

Said bass cab is now dong duty as my party bass box