6 ohm 8x10 bass cabinet

[apostrophe5]

Hi Y'all --

I just purchased an interesting vintage Sunn bass cabinet--don't know what year it is, but got it at a bargain basement price... it's 6 ohms w/ 8 10" speakers that are angled in toward each other, which seemed a little unusual to me.  Looks to be from the 1970's.  Does anyone know anything about what year this might be or any info at all?  Also, while we're at it, does anyone know what wattage a 1973 Coliseum bass head might be?

[coliseumboy]

The coliseum bass head was a 300 or so watt head that peaks at 880 watts


Joel
(another)

[briann]

correct me if i am wrong (because i realllly want to figure this out)....

that bass head is solid state (if i remember correctly), and i thought that solid states can only produce half the wattage taken from the wall.. so i dont see how its peak can be 880... and my sunn concert bass and concert lead.. supposedly peak at 350... i mean it gets fucking loud, but 350??

somebody who knows more about sunn amps than me.. straighten me out..

[tube]

"that bass head is solid state (if i remember correctly), and i thought that solid states can only produce half the wattage taken from the wall.. so i dont see how its peak can be 880... and my sunn concert bass and concert lead.. supposedly peak at 350..."

 i never learned that one in school!

 the function of power output from any amp is controlled by the available voltage driving a load. if you can transfer about 40 volts into an 8 ohm load, you can generate about 100 watts. rectified ac of 115 will produce around 70 volts dc (115 x .707) and should be enough to easily produce 200 watts into an 8 ohm load. into 4 ohm loads, you'd be in the 400 watt range, at 2 ohms, 800 watts.

 in all honesty, car stereo amplifiers and guitar amps weren't regulated by the FTC (federal trade commission) like stereo equipment, which was supposed to benefit consumers when comparing specifications. still, sunn equipment was fairly conservatively rated and the coliseum's rated output was given as 300 watts RMS (root mean square or averaged power) and 880 watts PEAK (or music power) which doesn't reflect anything except the peak to peak output over a very short measurement period.

 on the input side of things, what you see on the back panel near the power cord's strain relief that says "120vac 60 hz 400 watts" converted to an amperage would be 3.33 amps (400 / 120) which is hardly a strain on even a 15 amp circuit breaker.

 another thing about electrical power output from any amplifier and it's relationship to acoustic output. with the highest efficiency speakers available, one must provide 10 times the electrical output of the amp to achieve a 3 dB increase in acoustic output. this should indicate the relationship of a coliseum amp to it's little brother in the concert series. if you wanted to double the loudness of the concert amp's 200 watts you would have to apply 2000 watts. the coliseum amp therefore is only able to play "moderately" louder at a mere 300 watts.

 just my 2 cents  

  best regards, tube

[Anonymous]

"if you can transfer about 40 volts into an 8 ohm load, you can generate about 100 watts."

Actually the formula is voltage squared divided by resistance.  

(40 * 40) / 8 = 200 watts


"rectified ac of 115 will produce around 70 volts dc (115 x .707)"

AC measurements are usually RMS voltages.  This means the capacitor input to the power supply filter will charge to peak voltage.... so the maximum voltage would be 115 * 1.414 = 162.61 volts.  This maximum will be reduced by resistance in the power supply and any loading.

[tube]

"if you can transfer about 40 volts into an 8 ohm load, you can generate about 100 watts."

Actually the formula is voltage squared divided by resistance.  

(40 * 40) / 8 = 200 watts


"rectified ac of 115 will produce around 70 volts dc (115 x .707)"

AC measurements are usually RMS voltages.  This means the capacitor input to the power supply filter will charge to peak voltage.... so the maximum voltage would be 115 * 1.414 = 162.61 volts.  This maximum will be reduced by resistance in the power supply and any loading.

 hi guest!

 i went to college post 60's and i appreciate your paying enough attention to make the corrections. i always confused .707 and 1.414 in my "from the hip calculations."  

 the power from your wall socket is 115 vac peak to peak, not rms. it seems to me that the ac is rectified before it hits the big filter caps. rectified ac charges the caps to the average (rms) value of the 115 volts (peak to zero volts, remember that the rectifier folds the negative part of the sine wave into a positive pulse - ~~~~ into ^^^^) which is .707 of 115 volts (the rms of 115vac.)

 and yet even with your technical adjustments, my arguement is still quite the same. barring a bizzarre condition in the primary windings of the power supply transformer, the electrical requirement of the amp's input side isn't high enough to give a wall socket trouble and an amplifier is capable of much higher outputs than half the rated input at 115 vac.

 my nick should tell you which electrical theory i ascribe to. i learned current flow back in the old days and still cycle circuits using it instead of your new fangled hole flow theory. especially useful when dealing with diode tubes.

 i also slipped in memory on the voltage to develop 100 watts which i now recall from my old amp development days as being 28.37 (included some sag and inefficiencies.)

 anyway, thanks for getting my back.

 best regards, tube

[MUnder7782]

wanna sell it?

[iammr2]

I believe the Sunn Coliseum Bass as well as the Coliseum 880 were both rated at 300 watts into 2 ohms.  May not seem like much but they were loud.  Won't even guess about the 880 watts peak but it seems I've heard that before.  Is that feasible, Tube?

Never seen or heard of an 8x10 cab from Sunn.  Doesn't mean it's not true though.

[tube]

iammr2,

feasible and true. the coliseum was rated at 300 watts rms into 2 ohms and 880 watts peak. it's not uncommon in well designed amplifiers to find that kind of headroom, although i believe in the case of the coliseum, you'd find that the ability to generate that high power is limited to short term bursts measured in milliseconds. still, if you slap a bass, the transient power will deliver the attack without driving the amp into clipping.

a maserati car might be capable of speeds of 200 miles an hour, but you wouldn't generally drive it that fast. when you drive it 70 mph, it purrs like a kitten. pardon the analogy, but it fairly represents using an high powered amp at a conservative output level.

best regards, tube