[MusicNutt]

I'm looking at buying a Sansui AU-505. Anyone have feelings one way or another?

 

[merkil]

Quote:

Merkil, I'm looking for a full bodied sound with strong bass. I also like the tube sound. Having listened with the HD555, the sound is more fuller with heavier bass presence. But the HD650 sounded thinner in comparison. Just wondering if these vintages don't output sufficient voltage swing?

These old 70's receivers have plenty of power and usually produce more wpc then that is stated in the manufactures specs. Do some research on 70s Marantz as I think you will enjoy that sound, a lot of people do. Fully body, tube like, listenable for hours. Look for a local deal and then go audition it with your headphones before you make a final decision. You don't have to buy it but that way you at least tried it out and can look for a good deal elsewhere, unless the deal is already sweet. 

 

[Silent One]

Usually, the understated specs leaves us grinning...

 

[Argybargy]

Quote:

Anyone can recommend a vintage amp/receiver that can match well with high impedance cans e.g. HD650? My Kenwood KA5500 doesn't seem to synergise well with the 650s but great with low impedance cans.

 
Vintage Harman Kardon twin power receivers have a warm full bodied sound: the 430, 730 and 930 are all good, very under rated and cheap on the bay.
The HD650 for the short time that I owned it sounded very good on the 730 and three thirty (non twin power model).

 

[Argybargy]

+2 on vintage Marantz, but definitely pricier than HK stuff.  HD650 sounds great from a 2230 or 2270.
 

 

[captouch]

Quote:

 
Vintage Harman Kardon twin power receivers have a warm full bodied sound: the 430, 730 and 930 are all good, very under rated and cheap on the bay.
The HD650 for the short time that I owned it sounded very good on the 730 and three thirty (non twin power model).

 
+1 on HK - I forgot about them, even though I picked up a 730 last year.  Nice receiver and it is very smooth/warm and many people say "tubey".

 

[merkil]

Vintage Harman Kardon twin power receivers have a warm full bodied sound: the 430, 730 and 930 are all good, very under rated and cheap on the bay.
The HD650 for the short time that I owned it sounded very good on the 730 and three thirty (non twin power model).

HK are also nice. Unfortunately where I live they don't come up to often.

+2 on vintage Marantz, but definitely pricier than HK stuff.  HD650 sounds great from a 2230 or 2270.

 

They are sought after units that's for sure, I think their prices are somewhat inflated right now but you definitely have more choice of units to choose from than other vintage brands. Well at least where I live, there is always a variety of Marantz for sale.

 

[Rossliew]

Thanks for the feedback all, very grateful for it. Unfortunately, it is difficult sourcing the amps mentioned especially the Marantz ones. More sansui floating around though.

 

[captouch]

Quote:

Not really, it's quite rare in these parts and good models often sold before we get to try em. Speaking of Sansui, how's the au-999? Or would the au-317 be better?

 
Sorry, don't have experience with either one of these.  The x17 line does get talked about in a favorable light a lot though.

 

[Rawrbington]

if a marantz 2245 doesn't make the HD650 sound full then I don't know what full sounds like

 

[Skylab]

Quote:

if a marantz 2245 doesn't make the HD650 sound full then I don't know what full sounds like

 
Indeed...given that the HD650 is not a lean sounding headphone and the Marantz 2245 is a warm sounding receiver...

 

[wualta]

Exactly. I'm thinking something's not right somewhere. "High" impedance (we had much higher back in the day) is no problem for one of these amps/receivers if everything (including the headphone) is working as it should. Do a basic check before buying another amp. Start with a DC offset test. Clean the headphone plug-- they can get surprisingly dirty. Clean the headphone jack with contact cleaner on a cotton swab or put some on the headphone plug and work it around.

 

[Rossliew]

Once again, thanks for the advice, will try cleaning the headphone jack first.

 

[Argybargy]

 

 
This is a 1969 or 1970 Three Thirty (earlier version).  Before starting the restoration I took a listen and thought there was some potential: the background was quiet and detail retrieval was good (for a vintage receiver).  However, this was by far the warmest and most bass centric receiver I had ever heard – a 9 out of 10 on the bass-o-meter.

I searched but could not find a schematic for the three thirty and to make matters worse the PCB is not labeled.  This caused a few problems where I had to just guess and wing it. 
 

 
 
There are some peculiarities to this receiver.  The phono board looks odd with all the components mounted tombstone style, even though the chassis was roomy.  There is no power supply board or tone control board, instead a rat’s nest of resistors and film caps surrounding a few pots.  Soldering in this mess took patience and a steady hand.
 

 

 

Swapping out the main filter cap, power supply cap and output caps immediately cleaned up the warmth and wooly bass, and returned the treble.  The main filters went from 2200uf to 3900uf and the outputs from 1000uf to 2200uf.
 

 

The first board to go under the knife were the two amp boards.  A significant change was replacing 14 1uf electrolytics with Vishay polypro film caps (the grey boxy ones in the photo).  Incidentally, the 14 film caps cost about what I paid for the receiver - $40.
With the amp boards done, I took a listen and was shocked to hear all of the warm wooly bass right back.  It had to be the film caps.  I thought about cutting half of them out and using 1uf Muse BP and 1uf CDE polyester  films which I know are on the brighter side.  Fortunately, I waited a couple days and after 40 hours of burn in, all of the warmth and bloomy bass disappeared.  Wow, this was the most dramatic instance of cap burn-in I’ve ever heard.
 

 


You can see in the photos the large boxy brown caps.  These are 2uf KBG-MN Russian PIOs bypassing the large electrolytics.  1uf K40Y-9 PIOs are used on the electrolytics on the bottom side.  I had to create a shelf (using leftover Ikea parts) to mount the PIOs over the output caps.
 

 

Summary of the restoration:
All resistors changed to mostly Vishay Dale 1% metal film.
All electrolytic and film caps replaced
All 10 lamps replaced with LEDs
Tuner string replaced (soldering mishap)
PIO bypass caps
Remount output transistors

Total cost in parts was about $300.  As a point of comparison, the parts for my Marantz 2270 cost about $400.

So how does it sound?

Sublime.
Warm, mid-centric  with a sparkly treble and airiness that captures the shimmering decay of cymbals.  The bass is organic and rich, but not tight and impactful like a modern SS amp.  I think this sound sig is a mixture of the low noise resistors, all of the polypro film caps, and the big PIOs.
The LCD-2 and HE500 particularly sound good.  You might not think this little receiver has enough power, but the rated 17wpc is probably too conservative, it’s more likely 25wpc.  I would guess there’s about 2 watts on tap through the headphone out (into the orthos).

 

 

[parbaked]

Well Done!