Sansui 505 Rebuild Wolf in Sheep Clothing in 5 steps!

patfont

patfont

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I grabbed a 505 off of BT which already had an excellent rebuild done. And this little guy punches well above it's weight and sounds phenomenal! I would like to take this little amp to places it has not seen before sonically. I love the sonic signature and would like to make sure the finished product stays cut from the same cloth. What I aim to do is push it to another level so it competes with some much more costly audio gear.
 
(Step 1) Here is the 1st step and nothing wrong with the Nichicon FG couplers. To my ears the 2 best sounding coupling caps are the Nichicon KG's and the KS. They are both more transparent then anything else I have heard and the KS are actually a whisker more so then the KG's. I usually like to use the KS for power supply value and size permitting. For this applications I like the KG Super Through they just have a little bit of punch to them, as the KS are a more linear sound. The punchy KG's fit the sonic signature of the 505 for me.
 
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So I want to go stock original diameter and fill up the space of the old coupling caps. So will go with KG Super Through 35mm caps.

You can see below in the pic I used a 1/16 inch hand drill, just using the center hole as a guide space your holes with 10mm centers. The KG's will then snap right in.


This is how I got the 505:



Here is the KG's ready to go:




Carefully drilled holes by hand, takes no time at all:

 
Wolf in sheep's clothing - Love it !. Mine is tweaked and modded too. it is actually my daily driver among some better spec'ed gear around the house. It is a little gem. I can hear it's limitations, but its "big" beautiful voicing, and low-end characteristics makes you forgive it over and over. I'll be curious how far you can take it.

I had some luck in adding 15uf polyprops to the output couplers, but that seems to help more so when you listen to digital content from less than stellar sources. Here the polyprops help clean up voices and higher notes for a more pleasing sound. The difference is subtle and I ended up keeping them on after some A/B'ing
 
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Well let me know if you think I missed anything when I am done since you have already tweaked your 505. And yes the 505 is like the beautiful girlfriend who you just have to forgive for any short coming she may have!:D






stereofun said:
Wolf in sheep's clothing - Love it !. Mine is tweaked and modded too. it is actually my daily driver among some better spec'ed gear around the house. It is a little gem. I can hear it's limitations, but its "big" beautiful voicing, and low-end characteristics makes you forgive it over and over. I'll be curious how far you can take it.

I had some luck in adding 15uf polyprops to the output couplers, but that seems to help more so when you listen to digital content from less than stellar sources. Here the polyprops help clean up voices and higher notes for a more pleasing sound. The difference is subtle and I ended up keeping them on after some A/B'ing
Click to expand...
 
Well got the big boys in they are exact height and diameter of the stock caps:

Top side view:




Here is the bottom view:

 
(Step 2) replace D001 common cathode diode on the filter board with a modern fast switching soft recovery type. I was going to make a common cathode as I have done in the past by joining 2 diodes together but Leestereo had abetter idea and recommendation so I went with his pick!

Even if you are not going to replace this when you rebuild your filter board, I would desolder the 3 wires running to each leg of the diode and clean re-tin and then re-solder. The joints/connections did not look good.

Here she is:




And out she comes:

 
These remarks are for entertainment purposes only and YMMV.

Replacing the diode to a modern fast switching/soft recovery diode package yields these results-there was a valid improvement in high end smoothness and detail, and the background is quieter. You can hear small shadings in the background of recordings they may have been masked before.

Here is the Mouser part: have fun!


http://www.mouser.com/ProductDetail...mb9X4QbqcdnP5RbRzQ5cREhQSf3pDnOnlDkyuAQP97w==




stereofun said:
What was the replacement leestereo recommended in leu of the rectifier diodes ? Better sonics ?
Click to expand...
 
On the 555 I just did I put a C0G ceramic on the amp board. For this 505 I wanted to try a Wima Polyprop. If there is room I slightly prefer the PP. A lot of places when ceramic disc caps are used have very limited space, so just have to go with what will fit and if there is room then your preference.

(Step 3) This is for location C801/C802 which are in the signal path.

To my ears these really clean up the high end.


Easy R&R here:





 
Wow the Nichicon KG is getting pulled, the KG is an amazing cap but.......................got a Jensen 4 pole here!


(Step 4)

 
The Jensen 4 pole is in and running! You can hear this baby right away, but starts sounding it's best after about 50 hours.



 
(step 5) Adding 2 teaspoons of sweetness. Install 2 AMRG resistors at what I am calling the preamp input location. Not actually the first resistor in the pre but first before the transistor.

 
patfont said:
On the 555 I just did I put a C0G ceramic on the amp board. For this 505 I wanted to try a Wima Polyprop. If there is room I slightly prefer the PP. A lot of places when ceramic disc caps are used have very limited space, so just have to go with what will fit and if there is room then your preference.

(Step 3) This is for location C801/C802 which are in the signal path.


Click to expand...

What value are the Wima's that you used at C801/802? 47pF?
 
I also noticed that in your excellent 555A build that you used a pair of bipolar caps at C807/808 for reasons explained in that thread. But here on the 505's F- 1266-1 board you went with Silmic's I believe. I was just curious if the same reasons for a pair in the 555A also pertains to the 505 since the boards seem identical.

Thanks!
 
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patfont said:
all done, and yes makes a difference sonically!



Click to expand...

Thanks for passing this idea on! Looks very convenient.
Do you have a sleeve on the nearby capacitor to protect it from heat emitting from the new rail rectifier? Where does one get those?
 
Not much attention seems to be paid to the headphone out of the 505 in any of the rebuilds I've seen.

From the schematic it appears that the headphone out comes right off of the C 819/820 caps with one resistor in each path. Respectively R 861/862 470 ohm.

This seems like a nice resistor to tweak for more sonic goodness. Any suggestions? Your AMRG resistor in another circuit has me curious about R861/862 possibilities.
 
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