This was an offering from Yamaha back in the 2009 era and was part of the entry level NS-P270 5.1 channel loudspeaker system, I am offering only the subwoofer component.
This sub woofer is suitable where the user wishes to reinforce the bass response (manufacturer states 30Hz ~ 200Hz range but see my testing notes below) of a small stereo or multi-channel loudspeaker system that is being used in a small/medium sized room, garage etc adding low frequency response capabilities in sound systems that often have inadequate loudspeakers to provide proper bass response - you can't expect much from a tiny 3" speaker that is trying to reproduce a range of 50Hz up to say 15Khz, its just not going to cut it. Add a sub-woofer like this unit and at least those little speakers in your system can focus on the higher frequencies!
In my opinion, this should be considered as an entry level sub woofer and there are much better subbies around (for a LOT more $$$ too) - it does the job adequately and it has the Yamaha name!
Please read below (Testing Section) about how to connect one of these to your own audio system.
YAMAHA - Powered Sub-Woofer
Designed in Japan
Manufactured in China
Model: SW P270
POWER: Australian 240V AC domestic power socket (maximum 40W power consumption)
I have seen a LOT of dodgy information about these sub-woofers online, here is some important information DIRECT FROM THE MANUFACTURERS TECHNICAL DATA SHEET
I can supply the multi-language User Guide from YAMAHA if you request it (copies of some sections are in this advertisement)
Single RCA audio input female socket
Input impedance 12kΩ
100mV input sensitivity to achieve full (50W RMS) power output
Peak output is 100W (not continuous)
Loudspeaker used (the driver) is 160mm diameter
Built in low frequency filter, this means the amplifier and loudspeaker are focusing on reproducing frequencies in the 30Hz ~ 200Hz range only.
NO variation of the band or centre frequency is possible, the filter range is fixed
Built in power amplifier
Rear ON-OFF push button switch
Rear input level rotary control
SPECIAL FEATURE:
This sub-woofer is not just a loudspeaker stuffed into a box, Yamaha have designed and created what they call Advanced YAMAHA Active Servo Technology, let's just call it AYAST!
Here is the theory behind the AYAST technology ... (partial copy from the User Manual - lots more information in the manual)
The theory behind YAMAHA Active Servo Technology is based on two factors: the Helmholtz
resonator and negative-impedance drive.
Active Servo Processing speakers reproduce the bass frequencies through an “air woofer,” which is a port or opening in the speaker’s cabinet. This opening is used instead of, and performs the functions of, a woofer in a conventionally designed speaker system. Thus, signals of low amplitude within the cabinet can, according to Helmholtz resonance theory, be output from this opening as waves of great amplitude if the size of the opening and the volume of the cabinet are in proportion to satisfy a certain ratio. In order to accomplish this, moreover, the amplitudes within the cabinet must be both precise and of sufficient power because these amplitudes must overcome the “load” presented by the air in the cabinet. By employing negative-impedance drive circuits, the amplifier is able to generate precise, low amplitude, low frequency waves with superior damping characteristics. These waves are then radiated from the cabinet opening as high-amplitude signals. The system can, therefore, by employing the negative impedance output drive amplifier and a speaker cabinet featuring a Helmholtz resonator, reproduce an extremely wide range of frequencies with outstanding sound quality and low distortion.
The folks who love to impress their friends with high tech talk will love this! For most others, this really means SMALL BOX = LOUD BASS
DIMENSIONS:
220mm wide x 365mm height x 370mm deep
WEIGHT: 9Kg (Yes, she is a heavy little beastie!)
NOT SUPPLIED WITH THE PS-270:
User manual - unless requested and this will be an electronic copy, not hardcopy
NO Y or straight audio cables ... these are not hard to come by, your requirements will be determined by your own audio setup and equipment flexibility
COSMETIC CONDITION:
Black Ash veneer cabinet is in very good condition, no corner join separation at all and no marks or scratching of the veneer.
NO structural damage to the wooden cabinet at all, including corner knocks.
The front cloth grill is clean, no tears or rips!
TESTING:
Some basic connection information to begin with:
ONLY ever send line level audio signals to this sub-woofer, NEVER direct from the power amplifier speaker outputs (the audio level will be way too high) Now this actually doesn't mean you cannot connect to the amplifier loudspeaker outputs but you would need to obtain a "level convertor" which drops the output of the amplifier to levels that are suitable for use with this sub-woofer equipment. These are not difficult to find, try a place such as Jaycar Electronics for starter's
This sub woofer is very suited to the older, high quality integrated amplifiers which have a very handy link system between the pre-amplifier and power amplifier sections of the amplifier. By using a Y cable you can easily access the low level audio between the preamp and power amp sections of the amplifier and take this signal to this sub woofer unit.
During my testing I used one of my favourite "oldies", the NAD 7150 integrated amplifier.
Some power amplifiers will also have a separate sub-woofer output - these are not so common in domestic consumer gear but sometimes I have come across them.
I have included a composite photograph of these connections which can be found on many amplifiers, hopefully these help make sense of what I am talking about.
I used this sub woofer for quite some time many years ago but moved onto "bigger & better" low end loudspeaker systems, this one has just been sitting in the storage area until last week.
Connected into the audio signal path of the 7150 and fired it up (Green LED at the rear lights up). It is still working fine, no noises (50Hz hum) when there is no signal and I then adjusted the input level control to a suitable sound level (small room) and heard good thumping bass frequencies and no "funnies" although the small speaker still can have difficulty with the very low frequencies (sub 50Hz) - that cone has to move a long way and quickly, sometimes I felt it was struggling to keep in the race.
Personally I feel that the "true" useable low frequency range is more like 45Hz ~ 125Hz, look at the graph and this is the optimal frequency band, Yamaha have instead used the 3dB points to give the impression of a wider low frequency range.
When set up properly, the bass audio has a nice clean sound, no rattles or other strange noises - my test audio recordings were across a range of genre's, from African tribal through to Drum N Bass and the resulting bass line is truly quite impressive, the low end (bass) really pumps!
Keep in mind though, these are low frequencies and they will penetrate walls easily. This means your neighbours will hear every beat of your music if you are not cautious (and they may call "Noise Control")!
