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A&R Cambridge A60 tidy up

Hi Andrew

The bypass caps are just a bit extra "belt and braces" type of thing. They are pretty cheap and so an easy extra mod. The original tip came from fellow PFM'er Robert.
You don't have to add them but might as well whilst the cover is off and the soldering iron is going.
 
Sorry, Julian. There was one more thing.
C22/122 is in the list of 47uf caps but on the circuit diagram for the A60+ and on my amp it has been changed to 10uf/50v L L. Does it matter which? What does L L mean? Thanks.
 
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Andrew Ponsford said:
Amp sounds fine on cd, tuner etc but phono still lacks high frequency. Any thoughts anyone?
Click to expand...
What’s your cartridge? It may need more capacitance than the 100pF I believe was standard for the A60.

I have an A&R type that sounds dull at 100pF. It would probably sound best with 470pF (or whatever the value is exactly) that many MM cartridges were optimised for in the 70s.
 
Weird! The 1042 is supposed to like less rather than more pF.

You could try adding an extension RCA cable to the arm cable to add capacitance & see how you like it. OTOH I don't feel the A60s phono stage is as good as the line level inputs (not the discrete one in my A60 anyway). Do you have another phono stage to try, even in another amplifier that you can direct through the A60s Aux or Tuner inputs?
 
The 1042 likes 150-200pf. I could try 100 pf extra across the cartridge loading pins.
I was going to bid on a phono stage on ebay earlier. Will look tomorrow.
I’m sure this is a gradual effect I am hearing and that it used to sound ok. As above I replaced all the electolytics including those in the phono stage.
 
Durmbo said:
What’s your cartridge? It may need more capacitance than the 100pF I believe was standard for the A60.

I have an A&R type that sounds dull at 100pF. It would probably sound best with 470pF (or whatever the value is exactly) that many MM cartridges were optimised for in the 70s.
Click to expand...
Phono input capacitance varied over the A60 issues, with the earliest (s/n 0001- 3980) having 220pF fitted with 56k in parallel*, followed shortly thereafter (s/n 3981 - 13249) with 100pF, again with 56k resistance. With the introduction of NE5534 (s/n 13250 - 19999) loading was again changed, this time to 47k//47pF** and remained so through s/n 20000 - 25501. I don't know if the following exactly coincided with A60 Plus, but cartridge input loading finally settled at 47k//100pF from s/n 25502 on to end of production.

* Note that 56k resistance will result in a slightly higher amplitude HF resonance peak than will 47k.
** The drop to 47pF may have coincided with their introduction of the optional cartridge loading module, i.e. easier to go up than to go down.
 
Yes. Every time I play a record. Audio Technica cleaning fluid, brush and carbon fibre pad. There was also some minor work at the other end of the cartridge which improved things a bit but led me back to the phono stage.
 
Then something is very off, and I doubt that that is cable. For first I would try another amp/phonostage.
 
Andrew Ponsford said:
Yes. Every time I play a record. Audio Technica cleaning fluid, brush and carbon fibre pad. There was also some minor work at the other end of the cartridge which improved things a bit but led me back to the phono stage.
Click to expand...
Does yours happen to have an optional universal cartridge loading module fitted? This will be a small vertically mounted card located in the back LH corner. If so, something that is important to note here is that A&R supplied two versions of these, one for MM loading dubbed ULM/M ('M' for moving 'M'agnet), the other ULM/C ('C' for moving 'C'oil). You don't want the MC loading module in if using MM.

ULM/M Universal Loading Module:
A60-universal-loading-module.jpg
 
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