AU-517 vs AU-719 - a post-recap comparison

[pete_mac]

Thanks for the comments!

To be honest I can't attribute any sonic changes in the amp to the minor increase in capacitance. I do feel that fitting new filter caps has tightened up the bass response, but that is likely to be a result of the new capacitors vs the increased capacitance.

Higher capacitance will result in slightly higher inrush currents and therefore a slightly higher load on the power switch on start-up, as well as diodes etc. However, such a small increase is within the tolerance specs quoted for the original capacitors anyway.

I use RS Components, element14 and partsconnexion for most of my parts. Mouser and digikey are too expensive regarding shipping for those of us in Australia.

 

[kevzep]

I use RS Components, element14 and partsconnexion for most of my parts. Mouser and digikey are too expensive regarding shipping for those of us in Australia.

This is exactly how we roll in New Zealand too........$39NZ to ship a bag of caps from the US....Gotta seriously think if its worth it.....
I mainly use Element14.......RS has a crap website IMO I find it difficult to find what I want, whereas element 14 has a good website......

 

[LeeS]

Just received some gold-plated 5-way binding posts and some 5mm black perspex for the binding post conversion. I am going to CAD up a template for the black perspex plates so they are a drop-in replacement for the original plastic panels. I will then have the perspex laser cut and I'll probably make 3 or 4 of them if anyone is interested in one.

Have also just ordered some 12w Mills Non-Inductive 0.33R wire-wounds to replace those awful white ceramic ones on the driver boards with. Also ordered some nice ClarityCap ESA 250v 2.2uF Polyprops to add as decent quality by-pass caps to the four main PSU caps.

It's coming together now. I think I will fit an IEC socket to the chassis too, with some basic filtering components on it. That will do I think. As usual, I will add some photos when all of this occurs.

I then need to think about re-capping my TU-719 and my SL-QL1. They are of a similar age and are all original, so the caps in them are probably long overdue a change.

Cheers.

 

[phonomac]

Speaker terminal plates

Hello Lee,
I would be interested in one (or two) of the perspex plates for the speaker binding posts.

Let me know if you end up having some made. (I'm UK based as well)

regards

Angus

 

[Hyperion]

I would also be interested to know if this comes to fruition - hoping I might be able to use 1 or 2 for an AU-717...
(instead of for an AU-719) :scratch2:

Thanks Lee

 

[LeeS]

Hi Angus/John.

No problems, but I do tend to work at a snail's pace, so bear with me on this. I am not sure how big these things need to be yet and I only have 2 x A5 sheets of perspex so I am guessing I can get 3 or 4 plates out of each one. I will use up all the perspex I have and the laser work will be done by a friend of mine for free, so hopefully I should be able to get 6-8 plates out of the perspex I have, so I will keep 2 for myself (1 spare - you never know ) and there should be 4-6 left.

Watch this space and I will let you know when they're ready. :thmbsp:

 

[pete_mac]

Have also just ordered some 12w Mills Non-Inductive 0.33R wire-wounds to replace those awful white ceramic ones on the driver boards with.

Damnit... another thing to add to the list of 'nice to do' tweaks for the future.

 

[LeeS]

OK. Here are some photos of the latest upgrades/mods:

Mundorf main PSU caps with temporary 0.1uf Wima by-pass caps:

New ClarityCap ESA 2.2uF 250v by-pass caps:

New Mills 0.33R 12w NI wirewounds:

ClarityCap by-pass caps fitted:

New Mills vs old ceramics:

Mills bent and ready to fit:

..and fitted:

Comparison:

...and finally, in the chassis:

Adding these new by-pass caps and resistors has smoothed out the sound and seems to have removed a slight layer of grunge/distortion. Playing the amp at reasonable levels tonight induced no fatigue at all and although subtle, has been a worthwhile upgrade. I wonder if this is down to the extra headroom of the Mills at 12w rather than 5w. The old ceramics definitely showed signs of heat damage. They all seemed within tolerance, but who knows what they were doing under load. Maybe they'd gone noisy with age.:scratch2:

That's all for now folks....

 

[Curse]

Hello Lee,

Most interesting to see your work progressing - looking good :yes:

If you did end up with one spare perspex (I have an AU-517) that could do with proper binding posts... I was going to sell it, but not sure I can bring myself to do so!)

Dan

 

[pete_mac]

Skippy124 and I have just finished restoring a really clean AU-719 for a friend who really knows his audio gear, and is VERY impressed with how nice my restored AU-517 sounds in comparison to many modern amps out there.

We threw all of the usual nice bits at this one, but have tried some different capacitors this time around. There's a combination of Panasonic FC, Nichicon HE, Nichicon Muse KW, Elna Silmic II, Elna Cerafine and Panasonic ECQ-V. The binding posts have been upgraded with nice GaoFei copper items with a matte black body. These actually go quite well with the black Sansui faceplate and hood - they look better in the flesh than in the photos. The build quality of the GaoFeis is brilliant - I am very impressed. They look to be a very very good copy of Furutech binding posts. The binding posts have been mounted via the usual thin perspex/acrylic panel inserted behind the rear panel and secured by a few extra screws.

She sounds great and she also benched a bit over 125W per channel, both channels driven, before clipping. The 719 is rated at 90W per channel, both channels driven, so it's a great result! It's also worth noting that the amp made the exact same power into one or both channels (ie. no power sagging with both channels driven) so it shows what a good job the dual mono power supply configuration does!

I note that we retained the original filter caps for the time being, but did fit AXON polyprop bypass caps.

 

[Batong]

Those binding posts looks awesome. Those are the ones I'm getting after seeing this! Nice work Any nudies of that 719?

 

[Hyperion]

My goodness Pete - that looks very nice.

Ever since my supply of binding posts dried up, these were the ones suggested by Kale that I successfully used on my AU-D11 II, I have been looking around for a candidate to take their place for future upgrades. I have discovered I am very particular about what binding posts I like to use (the 'look' is important - but not everything) - these fill the bill nicely. :thmbsp:

Where did you get them from - can you post details ?

 

[pete_mac]

Those binding posts looks awesome. Those are the ones I'm getting after seeing this! Nice work Any nudies of that 719?

Thanks! I took a few low-light shots but they didn't turn out all that great. The internals look pretty similar to my own personal 719.

My goodness Pete - that looks very nice.

Ever since my supply of binding posts dried up, these were the ones suggested by Kale that I successfully used on my AU-D11 II, I have been looking around for a candidate to take their place for future upgrades. I have discovered I am very particular about what binding posts I like to use (the 'look' is important - but not everything) - these fill the bill nicely. :thmbsp:

Where did you get them from - can you post details ?

Thanks John. Pretty happy with the outcome! I sourced them from ebay. If you search for 'gaofei' they will appear. I used the short binding posts. About 19 pounds per set of four. Not crazy expensive, but not dirty cheap unfortunately.

Also, I do note that these are not 'solid copper' but are the usual brass with a thick copper plating. They are a bit more durable than solid copper posts which tend to be a bit soft.

 

[Hyperion]

Thanks for the info Pete :thmbsp:

 

[Batong]

Thanks! I took a few low-light shots but they didn't turn out all that great. The internals look pretty similar to my own personal 719.

I was kinda fishing for a pic that showed the backside of the new binding posts. I saw them on eBay aswell, did you need any plexiglass bracket of sorts, or was it just plug n' play?

 

[pete_mac]

No worries. Sadly I did not take one.

I used a perspex/plexiglass panel to mount the binding posts as per my own 719 in the picture below. They can't be mounted directly onto to the metal rear panel of the amp as the plastic shims/washers are too small in diameter.

 

[pete_mac]

A few more comparison pics of the 719 (mine is on top).

These 719s are breeding like rabbits!

 

[EPI-Center]

I have a 719 and think it's a pretty amazing amp.

 

[melofelo]

resist melo...resist....
these look great though :thmbsp:
also loving my au-719 at the moment..

 

[pete_mac]

Hi Less,

Mine the serial no is 220010008,but not sure when it was made,it can be used for 110v or 240v.There is a voltage selector behind the amp but there is NO power outlet provided so that we can connect tuner or other audio equipment.Weird cos most of the amp has it...,

Thanks,

Raj

My AU-719 serial number is:

220100329

It was originally a 220v model (label still on the back) with 3 x 2 pinned mains outlets on the back (2 unswitched and 1 switched). It has the 10,000uF 71v PSU caps. Not sure what market it was for, but I am guessing EU. The mains arrangement is exactly as drawn on the main AU-719 service schematic with the internal mains voltage selection jumper.

It had NO glue anywhere on ANY board inside and certainly no signs of ever having a recap or having glue removed. I think it left the factory with NO glue.

HTH.

Sorry for the delay in providing serial numbers!

My personal 719 is a May 1979 build, and the 719 restored for a friend recently is a September 1979 build. Both featured the glue. It would appear that the September 1979 model featured the updated driver board too. Skippy124 can probably shed more light on this as the driver board recapping on the September 1979 unit was his handiwork