Sunn 115BH or Magna 158 Speaker

[alfred8]

Hello, I recently purchased a Sunn 115 BH cabinet. It is loaded with one Magna 158 speaker 8 ohm speaker with a large square magnet, which is installed at a slant and the back has two 1/4" input jacks. The cabinet and the speaker are rated at 80 Watts; however I know that when these were made, high powered amplifiers weren't capable of pumping out the watts the way they are now. I'm using this as an extension cabinet to my 4X10, which will mean I'll be running about 350 watts at 4 ohms, or if I don't slave to the 410 and run it straight to the amp, I can run mono bridged at 700 Watts. My question is, what are the magna 158 capable of running at continously? Is it truly only slightly more than 80 watts? What is the size of the voice coil on the magna 158? Is the magnet ceramic or another material? Does anyone know the magnet size (in ounces)?

Any feedback, even if it's just a good list of the specifications on the cabinet or speakers may be helpful. I have already seen the catalogs (1979) on this website. Just for curiosity sake, I wouldn't mind knowing the year of the cabinet as well. Thank you for the information.

[..tube]

i really like the 115BH cabinet for it's ability to couple to any environment acoustically. the boxes even sound great outdoors.

 the magna 158 square magnet speaker had an alnico v magnet with an inch and a half voice coil, neither of which were ever noted for high power handling characteristics. they were pretty efficient drivers though, and the boxes' design enabled it to have deep bass and excellent transient response with a low power input.

 it would seem that you have 2 choices. the first is to be conservative with your use of your amp's level control (just because you have huge power doesn't mean you have to crank the amp to it's max output!) the second choice is to swap the drivers to ones that will handle the power.

 personally, i swapped the drivers for black widows. i notice that i have to hit them pretty hard to get the same tone from the boxes. they will handle the watts but don't have the same sweet tone as the magnas operated at lower power.

 another arguement is that it is held that an amp needs to produce 10 times it's electrical output to produce a doubling of sound pressure (or an increase of 3 db in sound level.) for a speaker that's rated at 80 watts not only would the 800 watts that would be required to drive the speaker to twice it's loudness burn up it's light mass voice coil, it would increase the travel of the cone structure beyond it's rupture point.

 in swapping to the black widows with their larger voice coil structures i think that i have to drive them harder (loss of efficiency) to get the same output.

   if you blow your speaker, i have 2 more for you.  

best regards, tube

[alfred8]

Thanks Tube. That was a very thorough description. I think I'm going to swap the drivers. That way, if I ever decide to get rid of the cabinet, I can preserve it in it's original form (in case a collector of vintage sunn equipment is interested). Why chance blowing a perfectly good speaker? Interestingly enough, I have also been looking at the black widows, but several people have told me that you can't go wrong with Eminence. They are just so darn expensive, especially for one with a 4" VC like the widow. I play both 4- and 5-string basses, and one of the main reasons I bought the cabinet was because I wanted more low end then my 4X10 could provide (especially on the low-B). Decisions, decisions. I think enough people have mentioned to me now that the tone just isn't quite as sweet with the black widow. I'll have took look at other options, maybe an eminence or a jbl, or even one of these new lesser known brands with a 3"vc (closer to my price range). What's the smallest VC size you would play with a 5-string?

Thank you again for the prompt feedback. Very helpful. I'll let you know if I ever need another 15" magna.

[bentbolt]

Eminence are made in the USA with a 7 year warranty. Not bad...

[..tube]

no prob!

 the cool thing about the black widows is that you can swap the basket with a new unit (between sets) in 10 minutes (with a drill driver) so that your rig isn't down for 2 weeks while you have any other speaker re-coned. if you are a professional musician, that could make a difference. the replacement baskets can be had in 4 and 8 ohm versions (the 10" may also be available in 16 ohms.)

 you will achieve very loud, low bass with the BWs if you hit them with your 350 amp. if your amp is bi-amp capable you would be able to adjust levels between your 4 x 10 box and the single 15.

 my personal take on a 5 string bass's range requirements is that a 15" and 4 x 10" combination covers the range nicely and gives one the transient response to produce a jaco pastorius/ victor wooten sound (hammered and plucked strings- sharp transients.) those guys seemed to favor the hartke transient response boxes and high powered modeling type amps. i think the sunn gear has way more stage presence and tone along with being somewhat easier to transport. in my own opinion, i think they make for a much more stylish set appearance (especially the tranparent black grille cloth with the white horn structure) when stage lighting is used - a sparkle instead of a black lump onstage.

 whatever you decide to do, the 115BH is an impressive cabinet. i predict a long and rewarding love affair for you!!  

best regards, tube