907 imos limited ....Need to know bias values and service manual

like i mentioned earlier the amp doesnot sound right . so there has GOT to be something amiss, and the tech that opened up my amplifier 2 years ago said he didnot have the biasing corrected because of NO manual .
i have a strong feeling that this could be the main reason for the amp to be sounding less attractive than the others
 
But my amp is the black one.

Its the AU alpha 907 imos limited.

i have same amplifier and told you my settings

you wont find the service manual here as this is very rare document. read above thread as it contains useful information and some screenshots from the manuals.
 
Thanks shavaliedd1 ,
Ofcourse thats a treasure youve shared .
Ill keep it for my repairs n references of the 907.

Apart from this , hiw well is this amp serving you . May i know ur setup . And how do you recommend it for best performance ..
I sold this amp 2 yrs ago and the owner hasnt used it at all and is in Russia for university.
1q
 
But i got it back from him for a spin . Coz hes gonna be back in 4 months... To pakistan .

May i i know your location n setup please.
 
But i got it back from him for a spin . Coz hes gonna be back in 4 months... To pakistan .

May i i know your location n setup please.

i use this amplifier paired with Vienna Acoustics bookshelfs.
My amplifier is 100% original with original capacitors and transistors. i did only repair of the output relays, i did this then realized that sometimes one of the channels plays 30% lower than another one. I do recommend you this repair as well, as sound quality may change dramatically.

in terms of performance my DC offset is within limits (as per manual shall be 0V), bias adjustment is 27mV.
the only concern is high temperature of the transistors - may go up to 50C

i like the sound quality except one thing - i have filling that my basses are to low and inarticulate but still i fully satisfied.

i'm from Russia
 
Ow i see.......
Thats good to hear....bass is low but very tight . Its not boomy or flabby.
What is ur comment on its imaging . And soundstage. Is it very good or soso
 
Ow i see.......
Thats good to hear....bass is low but very tight . Its not boomy or flabby.
What is ur comment on its imaging . And soundstage. Is it very good or soso
my room is small but i can feel clear picture and fully satisfied in terms of imaging.

soon i will move to bigger house so hopefully will discover more

also i do recommend you to try this amplifier in "power amplifier" mode. so you will eliminate problems with pre-amplifier board
 
Ok. I wanted to know the speakers they drive well. If any recommendations are there . I have a klipsch 280F with my friend where the amp is right now . As for me i made audax speakers . Components n drivers Made in germany and france .
 
This 907 here runs ice cool. I now believe that it must be biasing at a lower value and needs to be corrected.
I'd also want the face plate and volume pots switches to be cleaned up as they are also scratchy.... And disturbing the balance between speakers.
Hope its not a big deal.
 
I just re read this thread. U mentioned that your amp is a bit low in bass and is inarticulate .
I just checked out my bang okufsen okufsen with much sweeter bass and superb detail too. However sansui was superior in grip,detail and clarity... The only thing lacking was some low end bass was missing and the articulation was not as good as id like .....and i believe my bias is set at a low value of around 18...
 
Back
Top Bottom