Author Topic: Sunn Alpha Four & Sunn Model 1 PA speaker ohm load  (Read 360 times)

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Offline Shakou

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Sunn Alpha Four & Sunn Model 1 PA speaker ohm load
« on: January 01, 2017, 09:59:59 pm »
Hello all, I have recently acquired a Sunn Alpha Four (A4) several months ago and when it blew about 2 months back because of a faulty outlet (house built in the 60s, guy above me plugged a clothing dryer in and bam... what am I going to do?).  I paid top dollar to have it serviced because I fully appreciate what Im working with here and currently I power through a Furman Rack Conditioner, and I want to take really good care of it so I need some pointers towards safe practice in cabbing the amp, especially when I noticed that after visiting the repair shop the bottom plate (which is hooked into the transformer ground) was getting really hot as i was playing it guitar > pedal board > Head > 2 Sunn Model 1 50w @ 16 ohms speaker cabs, upon realization of the imbalance my fear was and is that I am improperly cabbing and causing an extreme imbalance and pushing the A4 too hard. and after a most of the day searching online to no success, i figured i'd try my luck here. 

I have some general questions regarding the 100w Solid State A4 head speaker output channels, much like other Sunn products it has 1 and 2 outs for stereo 4 ohm impedence (minimum). I need to understand if Sunn products with these 2 channel speaker outputs are wired parallel or series... for instance if i put 8 ohm load on A4.o1, and 8 ohm load on A4.o2 am i looking at a 4 ohm total load on the A4 head?

secondly how do the Sunn Model 1 wiring plates work? the speaker backplate says both outputs SM1.o1 & SM1.o2  are "wired together" but that does not convey if it is parallel wired or series wired. can i plug SM1.1 into SM1.2 and constitute an 8 ohm parallel load or is it 32 because its a series "addition" will both severely damage my amp?

if I want to daisy chain lets say 4 Sunn Model 1 cabs (i have 3 now) going A4.o1 > SM1.1 16 ohms > SM1.2 16 ohms ,  and A4.o2> SM1.3 16 ohms >SM1.4 16 ohms, would that constitute a proper 4 ohm impedance on the A4 and prevent overheating / damage? in the same configuration each speaker says its good for 50 w of continuous power, if the A4 is a solid state 100w by plugging in in this configuration would i be drawing 100 or 200w with 4 PA cabs or will that blow the amp?

On the sunn model 1s they have 2 ports that are "wired together to daisy chain into other cabs, if I have 4 model 1s, would it be safe to put 2 on alpha four channel 1 and 2 on a4 channel 2 for a maximum of 4 ohms running parallel on the alpha four side?

Cables - I've noticed the speakers work with TRS and Mono... but they should be wired with a true 1/4 " 16 gauge ts "speaker wire" am i doing something wrong by using trs instead of mono as is standard with certain cabs?

If you can offer me some answers I'd be very grateful there is little to no information on this product only that it's a monster of sound

Offline EdBass

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Re: Sunn Alpha Four & Sunn Model 1 PA speaker ohm load
« Reply #1 on: January 02, 2017, 08:09:45 am »
According to the schematic posted by Loudthud a few years back, the Alpha outputs are wired in parallel; just like pretty much every other amp on the planet.

You can wire any number or configuration of speakers you want just don't drop under 4 ohms impedance, higher impedance is fine as far as keeping the amp happy but you will diminish the amps output, and stress/heat, as the impedance increases.
The wattage rating of the speakers have no influence on the amps performance or longevity, but generally speaking the higher the rated watts are on a speaker the less efficient (sensitivity) the speaker is, and a lower sensitivity speaker will make less SPL than a higher sensitivity speaker will with the same amp.

TS connectors, and the lower the gauge the better; gauge gets more important as the length of the cable increases. That said, with standard connectors gauges under 12-14 can be tough to work with.