Sansui AU-505 Rebuild: Is this little integrated within shouting distance of the best?

[patfont]

Pat, great descriptions on the first post. Yes, you often have to increase the VR values... this is common on a lot of amps as you work on them. I keep flip flopping between the 555A and 505 as to which I prefer. The general consensus seems to be the 505 may have an edge in warmth/bass and the 555A may have an edge on clarity/space, but I'm sure the variations are subtle at this point and quite dependent on particular caps/parts used in rebuilds or condition of stock amps etc etc.

All in all, yes, the 505 is a well kept secret. Still, I think your 777 should beat it

Thank you!

I did have a 777, I prefer the 505 and the detail in the high end I have gotten out of this little Gem is on par with or better then 555/777. IMHO, YMMV

 

[smurfer77]

The "power cap" for example, 1st try was a Nichicon KG, the Nichicon KT screw terminal is the 2nd try, listened back and forth a few times. The Nichicon KT has lost the bypass cap-sounds better.
Amp board C801/C802 1st try C0G caps, changed to Wima films-fit perfect sound smoother in the high end.
Pat

Pat, I did similar experiments comparing output coupling caps on a 505 and KG was my favourite of the three I tried (some other nichicon and an Mundorf) and in all cases I preferred the sound without bypass caps. Also, I like WIMA in this signal couple positions too even though you will lots of people describe them as 'metallic' (this is just nonsense, like "metal film resistors sound metallic').

Again, great posts Pat.

 

[kevzep]

What you are seeing here is an almost finished rebuild, well what do I mean?
Certain locations and cap selections are done 1 at a time where I am inserting different caps and then listening usually to a "Direct to Disc" LP so I can hear every detail a change may bring.
The "power cap" for example, 1st try was a Nichicon KG, the Nichicon KT screw terminal is the 2nd try, listened back and forth a few times. The Nichicon KT has lost the bypass cap-sounds better.
Amp board C801/C802 1st try C0G caps, changed to Wima films-fit perfect sound smoother in the high end.
C807/C808 were Nichicon ES bipolar, switched to Silmic II sounds better.
*******When I say sounds better it means to me it blends best with the units sonic signature and strong points, and still sounds cut from the same cloth.
C803/C804 I tried Sonicap Gen II's like the stock caps better.
I do not just do wholesale changes on units to what should technically go in a position as the best part. I do try them but then I listen and compare.
The couplers were tried with and with out bypass caps, the bypass caps stay on, lowers the noise floor.
These are just some examples............

Answer to your actual question, the bypass on the power cap was a Vishay 940C .01uf same as the original.
And yes I do take time to let a said component break in to sound it's best before a change out.
I am impressed by this little 505 so took my time with almost all decisions on it.

Hope this helps.

Pat

Thanks Pat for the detailed response, interesting to say the least and something I'd like to do (your listening test method) if I had the time.
I am mostly restoring/recapping repairing for customers, so I have to make the best informed decisions about the way to approach the work I do, which is also often within a specific budget.
I also do not often work on Cap coupled amps, most are direct coupled with very little or no caps in the signal path, however I did some work on one an AU505 recently, it had been re-capped, but not at the exotic level you are doing here, even so I was very impressed with its performance.

 

[UMRKretread]

I have an AU-505, bought new in 1974 with a pair of KLH 6. Great unit! Dragged it out of storage for kid use, a few years back (seems they are not that interested). It sounds OK, but I really don't know much about electronics. Any advice on how to test for old age/bad components/etc?

 

[smurfer77]

I have an AU-505, bought new in 1974 with a pair of KLH 6. Great unit! Dragged it out of storage for kid use, a few years back (seems they are not that interested). It sounds OK, but I really don't know much about electronics. Any advice on how to test for old age/bad components/etc?

Hi, congrats on rediscovering your AU-505. It's a wonderful unit. I suggest you will get the best possible response be starting your own thread. A few pics never hurts too

 

[pingu_turbo]

Hi Pat, just getting on with my 505 rebuild now and (I hope you don't mind)), I'd like to take some cues from your work here?

My build (https://audiokarma.org/forums/index.php?threads/saved-goliaths-nemesis.873238/)

A couple of questions; could you advise what & how the dual diode (d001) fits on the filter board? Any specifics on what to use? Also could you advise what changes were made to the filter board?

...here's the new dual diode.

View attachment 1207391

On the coupler caps, what make/spec did you use? Also the coupling caps?

View attachment 1207399 Here are the bypass caps for the couplers on the bottom of the board. The couplers are Elna for Audio LAO.

Many thanks

 

[pingu_turbo]

duplicate post