why is this sansui so heavy ?

quadklipsh

Super Member
hi sansui folks,
could someone tell whats going on inside my sansui 907 IMOS limited REFERENCE amp that it had to be this heavy . o boy it weighs 31 kilos and by far its my heaviest integrated .
on the contrary i see it only has 85 watts to offer per channel.
and i hope it would do justice in driving my JBL 4410s.
i havent had the possession of these speakers yet but i hope that 85 watts wont be enough as many mentioned the need for a power amp well over 150 watts for such jbls.

just looking for your reviews and experiences.
 
I don't know that amp but is it dual mono supplied ie 2 power transformers? that would explain weight.all my dual powered HK amps are extremely heavy even my smaller hk 930 reciever
 
Broadly speaking, it's usually the large transformer(s) coupled with the steel chassis and aluminum face plate. Quality materials!
 
Generally speaking most of the weight of an Integrated Amp is in the Power supply, Heat sinking, and Case. A dual mono power supply doesn't necessarily make it heavier watt for watt than an amp with a single power supply. My Audio Design PA 100 Power Amp uses a single large power supply delivering 100 wpc and weighs 35 lbs. My Bryston B100 SST Integrated amp uses a dual mono chassis plus a third power supply for digital functions and weighs 30 lbs while delivering the same 100 wpc.

Circuit design, Power supply efficiency, and Current capability are other factors that play a role in the amps weight. My PA100 Power amp that is heavier than my Bryston Integrated amp with the same power rating but has an oversize power supply an 2x the heat sinking as the Bryston. It will drive a 2 ohm load where as the Bryston, as many decent amps is rated to 4 ohms.

The Sansui has an Oversize Power supply that may not be as efficient as some of the newer models and way more heat sinking than 85 wpc needs. Combine this with a heavy case and a more complex, likely all discrete circuit design (hopefully better) and you get a very heavy Integrated amp. The AU-D907 appears to be 21 kg according to audio data base.com BTY, Which is still a lot of weight for a 100 wpc (which is also listed) amp.

Don't be fooled by the 85 wpc rating (or 100 wpc as listed at audio data base.com) An Amp with this large a dual mono power supply and this much heat sinking is likely capable of peak power levels on par with many lesser 150 wpc seperate power amps. With music it is short term peaks that matter most, not continuous RMS power. That's important for light bulbs and heaters.
 
Last edited:
I believe that the sensitivity rating on those JBL's is 90dB at 1 meter with 2.83V (1 watt, given that they are 8 ohm speakers).

85 watts will give you more than adequate power for moderately loud (92dB or thereabouts, after accounting for two speakers, 8-10 foot listening distance and average room acoustics), plus another 12-15dB or so of headroom for transient peaks, depending upon dynamic headroom built into the amp.
 
Last edited:
Those JBL has 91dB sensitivity, which means the amplifier's possible power output becomes basically irrelevant. Anything will do.

Their power rating is 125W. Which means you'll blow them if you try to force that much through them (which will be impossible, as long as you still have functioning hearing).
 
yes they are like 91 db. my room is 13 by 14 . i want detail. i want bass that goes musically deep. i donot expect those subwoofing bass but all in the music should be offered i guess. im glad the sansui gets approval here .i hope it matches well too.
 
The Sansui has an Oversize Power supply that may not be as efficient as some of the newer models and way more heat sinking than 85 wpc needs. Combine this with a heavy case and a more complex, likely all discrete circuit design (hopefully better) and you get a very heavy Integrated amp. The AU-D907 appears to be 21 kg according to audio data base.com BTY, Which is still a lot of weight for a 100 wpc (which is also listed) amp.

Don't be fooled by the 85 wpc rating (or 100 wpc as listed at audio data base.com) An Amp with this large a dual mono power supply and this much heat sinking is likely capable of peak power levels on par with many lesser 150 wpc seperate power amps. With music it is short term peaks that matter most, not continuous RMS power. That's important for light bulbs and heaters.

Wrong amp my friend:

http://audio-database.com/SANSUI/amp/au-alpha907imoslimited-e.html
 
Yowza, that's heavy for an 80 WPC solid state amp. My Mac MC2225 is heavier at 82 pounds but it's good for an easy 250 WPC. I'm guessing that your Sansui is probably good for quite a bit more than its rated power but even 80 WPC should get those JBLs rocking. Enjoy it!
 
though its damping factor is 150 ,if i remember , the amp is so tight and gripping on the woofer that it sounds very accurate all the time. im guessing i sometimes feel the amp to be clinical and accurate rather than musical and relaxed . ofcourse it has its plus and minuses. maybe all speakers i tried are light weighted (not enough load and not large enough woofing diaphragms) thats why the amp never loses grip and sounds way too gripped and tight .
i once connected the luxman L505V, and it sounded a lot more relaxed and musical but with lesser grip. hence it makes me think i should couple the 907 to some larger JBLs ........
 
al907i_mos_limited_6.jpg
 
Heavy is good, right?

I think some AKer with too much time on his hands should put together a spreadsheet comparing amplifier and receiver weights with price.
 
Back
Top Bottom