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New (to me) A&R Cambridge A60

Hi, complete newbie here so sorry for hijacking the thread and probably silly questions. I've also recently been working on overhauling an A60 and have a couple of things I can't work out from browsing the forums. Any advice is very welcome!

If replacing resistors with metal film types, do I need to worry about the wattage rating? 0.25W resistors seem standard but will these be sufficient?

The A60 manual has a list of components in its suggested upgrade. I've noticed that some of these don't match the ratings in my amp, which is a first revision (without the IC regulators, 6800uf smoothing caps instead of 10000uf etc.). The parts specified match the later revisions according to the schematics. The manual says that the upgrade is suitable for all models -- does this mean that I can replace parts with the different specs listed in the upgrade? And if so, would this require all parts to be updated at once?

Thanks for any suggestions!
 
If you look a very old rebuild thread in DIY from me, mine was also an early one with different caps - think I documented the differences from Robert’s thread…can’t remember for sure.
 
I own an A&R A60, also a multimeter, I’m not the sharpest tool in the box so what setting do I put the multimeter to check the voltages across the resistors that are mentioned in this thread?
 
Geoffreybombom said:
I own an A&R A60, also a multimeter, I’m not the sharpest tool in the box so what setting do I put the multimeter to check the voltages across the resistors that are mentioned in this thread?
Click to expand...
Lots of different multimeters out there and some good reference materials on the webby.
See: https://www.sciencebuddies.org/science-fair-projects/references/how-to-use-a-multimeter

You are looking for starting 6mV DC across R63 and R163. ( Each channel ). It rises as the amp warms up and aim for 8mV - though unless you change the trim pots to multiturn getting that accurate on both channels might be a chore.

On a manual multimeter DC is usually indicated by V with a solidline and 3 dots below or the letters DCV.
The Range on mine I usually set to 200mV - though there are auto range sensing multimeters these days.
 
Better use film caps to replace electrolytics IMO - there’s a thread on here somewhere where I went stupid on my A60, value of caps inside far out weight value of amp really, but with right speakers it sounds fantastic :)
 
Dowsers plan to cram in loads of film caps was and still is a great read ! I am pleased it also sounds great.
In Robert's suggested plan there are a couple of film caps that are reasonably priced.

The Nichicon caps probably will do really well - though might be a bit esoteric for the humble A60.
Mind you - it seems these days due to supply chain and manufacturing issues - use what you can find at the price you want to pay.
I still have a pile of Panasonic caps left from a series of A60 refurbs. Even the cheap Jamicons make a great improvement.
 
When I restored my A60, I bypassed electrolytic caps with film ones where I thought they might be in the signal path.

I feel any amplifier benefits from components with tight tolerances & a reputation for reliability & longevity.

Eighteen years after its restoration, my A60 (until very recently my mainstay amplifier) has started to sound a bit off. I only used off the shelf electro-caps & it’s possible some have come to the end of their lives.
 
Thank you for your replies, Gents, planning a mid term A60 service and it happens I have some Nichicon ES bipolar caps in stock. I will change output trans as well and some drivers might be damaged..
I reckon (at least) the input caps close to the volume pot should be film ones (1uF?) as the original ones were.
Not sure I can justify more film caps, but it is a great read, and good to know the A60 circuit is responding well to further hard core mods!
@Dowser which speakers were you using? high sensitivity ones?

Btw does anyone happen to have a spare black source push-button?
 
geoturbo said:
Thank you for your replies, Gents, planning a mid term A60 service and it happens I have some Nichicon ES bipolar caps in stock. I will change output trans as well and some drivers might be damaged..
I reckon (at least) the input caps close to the volume pot should be film ones (1uF?) as the original ones were.
Not sure I can justify more film caps, but it is a great read, and good to know the A60 circuit is responding well to further hard core mods!
@Dowser which speakers were you using? high sensitivity ones?

Btw does anyone happen to have a spare black source push-button?
Click to expand...
Those rectangular switch caps may have been a standard Alps part. At least, I recall seeing them when looking for replacement round Alps button caps for a NAIT 1 restoration.

If what you find fits, but doesn't happen to be the exact profile, you could always replace all of them for a consistent look.
 
geoturbo

I probably have some black push buttons - there are a couple of totally wrecked T21 in my storage boxes. The same buttons are used for radio presets.
PM with a postal address and when I find them, I can put them in an envelope.

I used Wima 50v 1uF film caps for C9 and C109 - Part No: MKS02/1.0/50/20
 
@Operajulian thanks a lot Julian, that would be really great! I reckon I would use mkp4 or better mkp10 for the input cap provided there's enough room.. still to be checked.. pm on the way..
 
geoturbo said:
Thank you for your replies, Gents, planning a mid term A60 service and it happens I have some Nichicon ES bipolar caps in stock. I will change output trans as well and some drivers might be damaged..
I reckon (at least) the input caps close to the volume pot should be film ones (1uF?) as the original ones were.
Not sure I can justify more film caps, but it is a great read, and good to know the A60 circuit is responding well to further hard core mods!
@Dowser which speakers were you using? high sensitivity ones?

Btw does anyone happen to have a spare black source push-button?
Click to expand...

It doesn’t have the current, IMO, to drive SF Concertinos (terrible) or ESL63s (better, still not great). All other speakers it has sounded great with; MS 10 or 20is being their normal partner, but also great with various Mission and Monitor Audio bookshelf‘s I‘ve had through my hands. I’ll never sell it or the T21 I think :)
 
Posted a couple of A60 buttons to Italy ( from Canada ) today. In a birthday card envelope so you would think standard post sized and charges but no - CDN12.10 to post ( equiv to UK7.60)
And I had to fill in a customs declaration. What a mess for the post - no wonder everyone is using online messages and cards !
 
And sorry to the op.. I shall be able to open my A60 thread in the diy section hoping not to clutter further..:D
 
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