Like mpasanthosh says, the glue can get corrosive over time. Thats the opinion from the members over at audiokarma. You should read up, there's a lot of information there. Once you get this going, its a pleasure to listen to.
Sansui AU D707 ( AU819 ) on it's way
- Thread starter frend2001
- Start date
frend2001
Well-Known Member
So got the stepdown locally made and plugged in the amp.
I mated the amplifer to my 30 years old Enbee 6 way speakers ( yes it has 7 drivers in each speaker ). It's rated at 8 ohms and 120 watts.
So coming to the amp, well it does live up to all the aura, hype, awe, fame & cult value associated with it. Let me talk about the amp first then will come to the listening experience. It's a late 70s design and simply over engineered. Everything in it from components to design to execution screams quality and attention to detail and that pampers my pinpoint size ego and gives me a smug face with a hint of lopsided smile.
The amp has output transistors exclusively made for Sansui by Sanken which have insane specifications ( And are absolutely unobtainium).
Their ft is a whopping 20Mhz. Slew rate figures are 200v/microsec and rise time is 0.5 microseconds. This thing is fast, very fast.
The amp is direct coupled so it can literally amplify anything from 0 to 50000 Hz. Don't just raise your eyebrows yet ( not even single eyebrow if you are skeptical
), I understand it's beyond our listening range but it means nothing is filtered. The 300 VA transformer used in the amp is almost double sized then a normal 300VA tranny. The amp itself weights about 21 kgs. It doesn't have many exotic features but has essentially everything a audiophile may require ( not dream).
Even the flat amp and phono amps have DC topology so no compromise anywhere. It has a unique JUMP toggle which bypasses the flat amp and feeds the signal directly to power amp. You loose some gain but you gain shortest signal path. Now you may understand Sansui actually meant business.
Coming to the listening experience.
My speakers are past their prime so some headroom was accounted for in case no magic happens.
But magic did happen. Well as all the veterans advice that one must audition a system with songs which you've heard a million times so you'd able to understand and compare things easily. I have a huge pile of MP3 on my system from college days, couldn't delete as sourcing them then was a task. They are stored in proper chronological order and it felt bad to let them go so kept them. Among them are some tracks which aren't easily found today. So on a whim I picked up some mid 90's tracks on MP3 and offered them to the amp by foobar.
Any equipement worth it's salt will reproduce a well recorded source very accurately or almost attempt it. The fun part is, not everything that you like, is well recorded. So you will hear bad reproduction of a bad recording, period.
Now this amp here is able to make that agony passable.
This beast has squeezed out details from 20 years old mp3s, they are sounding so good and listenable that I acutualy can't believe my own ears.
That's my one line assessment of it gentlemen. Rest all things like accuracy, imaging, sound stage and all, are already all over internet about this finely engineered piece of audio equipment. (Although I'd again come up with more findings in coming days
)
"The audio gods must have been smiling down the engineers when they designed these things."
PS. : So far I've just been listening to all those 128 kbps MP3 ( Don't cringe
) and bloody gloating like Prez Trump having it in white house.
I mated the amplifer to my 30 years old Enbee 6 way speakers ( yes it has 7 drivers in each speaker ). It's rated at 8 ohms and 120 watts.
So coming to the amp, well it does live up to all the aura, hype, awe, fame & cult value associated with it. Let me talk about the amp first then will come to the listening experience. It's a late 70s design and simply over engineered. Everything in it from components to design to execution screams quality and attention to detail and that pampers my pinpoint size ego and gives me a smug face with a hint of lopsided smile.
The amp has output transistors exclusively made for Sansui by Sanken which have insane specifications ( And are absolutely unobtainium).
Their ft is a whopping 20Mhz. Slew rate figures are 200v/microsec and rise time is 0.5 microseconds. This thing is fast, very fast.
The amp is direct coupled so it can literally amplify anything from 0 to 50000 Hz. Don't just raise your eyebrows yet ( not even single eyebrow if you are skeptical
), I understand it's beyond our listening range but it means nothing is filtered. The 300 VA transformer used in the amp is almost double sized then a normal 300VA tranny. The amp itself weights about 21 kgs. It doesn't have many exotic features but has essentially everything a audiophile may require ( not dream).Even the flat amp and phono amps have DC topology so no compromise anywhere. It has a unique JUMP toggle which bypasses the flat amp and feeds the signal directly to power amp. You loose some gain but you gain shortest signal path. Now you may understand Sansui actually meant business.
Coming to the listening experience.
My speakers are past their prime so some headroom was accounted for in case no magic happens.
But magic did happen. Well as all the veterans advice that one must audition a system with songs which you've heard a million times so you'd able to understand and compare things easily. I have a huge pile of MP3 on my system from college days, couldn't delete as sourcing them then was a task. They are stored in proper chronological order and it felt bad to let them go so kept them. Among them are some tracks which aren't easily found today. So on a whim I picked up some mid 90's tracks on MP3 and offered them to the amp by foobar.
Any equipement worth it's salt will reproduce a well recorded source very accurately or almost attempt it. The fun part is, not everything that you like, is well recorded. So you will hear bad reproduction of a bad recording, period.
Now this amp here is able to make that agony passable.
This beast has squeezed out details from 20 years old mp3s, they are sounding so good and listenable that I acutualy can't believe my own ears.
That's my one line assessment of it gentlemen. Rest all things like accuracy, imaging, sound stage and all, are already all over internet about this finely engineered piece of audio equipment. (Although I'd again come up with more findings in coming days
)"The audio gods must have been smiling down the engineers when they designed these things."
PS. : So far I've just been listening to all those 128 kbps MP3 ( Don't cringe
) and bloody gloating like Prez Trump having it in white house.
frend2001
Well-Known Member
Lately I've been bugging FM Santhosh a lot. Apparantly the amp was running slightly warmer. So it was suggested to check bias.
After putting off the bias check for a month, I finally dedicated this day to bias check.
The amp has metal prongs wired to emitter of power transistors for easy accessibility, a very well thought of design addition.
So took the DMM and set down to it.
Findings : Left Channel : 32.1 mV and Right Channel 23.6 mV.
Bingo ! The high bias must have been cause of the slight warmish amp.
The manual suggests bias is 20 mV ~ 1 mV. So brought down the bias to 20 point something. More or less stable.
DC offset is within 5 mV for both channels.
Many thanks to @mpasanthosh. He's been great help and so patient with my noob questions. In fact he saved me from a great blunder while bias checking the amp.
Sol after bias adjustments, I think the dynamics of the left channel that was running on bias of 32 mV is slightly down. Or could be ear bugs ?
Any suggestions ?
Some WIP pics as usual.
After putting off the bias check for a month, I finally dedicated this day to bias check.
The amp has metal prongs wired to emitter of power transistors for easy accessibility, a very well thought of design addition.
So took the DMM and set down to it.
Findings : Left Channel : 32.1 mV and Right Channel 23.6 mV.
Bingo ! The high bias must have been cause of the slight warmish amp.
The manual suggests bias is 20 mV ~ 1 mV. So brought down the bias to 20 point something. More or less stable.
DC offset is within 5 mV for both channels.
Many thanks to @mpasanthosh. He's been great help and so patient with my noob questions. In fact he saved me from a great blunder while bias checking the amp.
Sol after bias adjustments, I think the dynamics of the left channel that was running on bias of 32 mV is slightly down. Or could be ear bugs ?
Any suggestions ?
Some WIP pics as usual.
reubensm
Well-Known Member
From my experience, its better to check the bias settings on a regular basis and also ensure that the chosen setting is within the compliance limits. Over-biasing can damage the driver and output transistors and also put greater stress on the power supply. Although I am not too much of a critical listener, i have often given the amp some time to settle down after bias calibration. Also play at moderately high levels. I also suggest that when we recalibrate something to factory specs, always tell yourself - i now have something which is performing as the designers intended. That will facilitate being confident about the outcome 
thomacho
Active Member
Recently got hold of a mint condition Sansui AU-D 707, posting few pictures here.
thomacho
Active Member
thomacho
Active Member
These are great sounding amps and difficult to get. Pair them with good vintage speakers and you will love them even more
thomacho
Active Member
Absolutely true, they do have a sweet sound unlike the current ones and as you mentioned, speaker matching is also critical.
thomacho
Active Member
Thanks, it was a cherished dream come true.
frend2001
Well-Known Member
Hi,
Congratulations for acquiring this Sansui.
How much did it cost ? Have you checked the boards for "Black Flag" caps ?
Regards
How much you paid for this amp?
thomacho
Active Member
Sorry for the belated reply, it cost me nearly 60k including duty. I had my friend open the cover and look at all the circuit and as per his opinion, the circuit board and components are untouched and the amp is working fine.
reubensm
Well-Known Member
looks in stunning condition, congrats on the great score
I was reading this thread and got curious to ask that has anyone here ever tried this or any other good Sansui amp models with any of the well reputed contemporary speakers other than only with vintage speaker models? I am interested to see if these amps hold on to themselves when paired with non-vintage speakers? Would someone find these as their primary amps if they need to pair it with say a Klipsch Forte or any of the Harbeths?
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