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A&r a60 - problem with speakers fuse

Of course I will keep it :D Did it make a good improvement on the sound on your a60?

However the Alps pot is not available on rs comp anymore. And they don’t seem to sell anything similar. If anyone know an alternative or a place to order one of those alps pot online would be very helpful (uk website preferably). On RS I only find the Alps Alpine range. Thank you
 
Yes the rapidonline one is 50k.

The one on Mouser is the right one but they only use fedex delivery which brings the total to almost 30£. I concluded it doesn’t come from UK
 
Rob88 said:
Of course I will keep it :D Did it make a good improvement on the sound on your a60?

However the Alps pot is not available on rs comp anymore. And they don’t seem to sell anything similar. If anyone know an alternative or a place to order one of those alps pot online would be very helpful (uk website preferably). On RS I only find the Alps Alpine range. Thank you
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It didn’t make a huge improvement on the sound but it gets rid of the scratchy noises for every and doesn’t need to be cleaned and lubricated anymore.
 
Rob88 said:
Yes the rapidonline one is 50k.

The one on Mouser is the right one but they only use fedex delivery which brings the total to almost 30£. I concluded it doesn’t come from UK
Click to expand...

How to destroy your sales in one easy go, oh well - probably explains why I haven't used Mouser for a decade......

The 'standard' ALPS pot (i.e. non blue) would (probably) be an improvement over the Omeg type usually fitted, I fitted a replacement Omeg to my A60 and didn't give it another thought - still sounds very good indeed.

The blue type is better but really only in terms of channel balance and longevity, they should be crackly noise free for longer (or so you would expect at the price !).

There are quite a lot of audio specialists selling the Blue ALPS.
 
WARNING. Do not buy Alps Blue pots from Farnell!! The one they sell as a volume pot is actually a linear balance control pot with a centre detent. I made them well aware of this a couple of years ago and even had correspondence via email in which I made it clear that it was the wrong part etc and which it should be. They thanked me for my help and assured me they would deal with the matter. They still haven't. You would think that having every single one they sell returned as not suitable and not as advertised would make the penny drop.... but it hasn't.
 
This "R50 mod" that the OP keeps banging on about... The only way I can see it being any improvement is by reducing the impedance between the driver bases. A capacitor of say 47uF should do it much better and is a lot simpler but it would take someone to check out instability issues etc that could arise before it could be recommended. Do not just try it anyway as if there is a real issue it's likely blown output stage again!
It can't be properly simulated and the tests would have to be done on a real unit.
 
Thanks for your answers.

The Alps 100k Hifi collective is selling is 6mm x 13mm and not the same reference. Don't I need 6mm x 20mm?
 
Arkless Electronics said:
This "R50 mod" that the OP keeps banging on about... The only way I can see it being any improvement is by reducing the impedance between the driver bases. A capacitor of say 47uF should do it much better and is a lot simpler but it would take someone to check out instability issues etc that could arise before it could be recommended. Do not just try it anyway as if there is a real issue it's likely blown output stage again!
It can't be properly simulated and the tests would have to be done on a real unit.
Click to expand...

In my enthusiasm over 10 years ago I did almost all of the Decdun mods to one of the first A60 amps I tried. To be honest it's Roberts mods on PFM that have stood the test of time and listening. I did try the R50 mods and did not get anything like the claimed improvements so I reversed the the mod. Not worth it in my opinion but that is just my experience.
 
Operajulian said:
In my enthusiasm over 10 years ago I did almost all of the Decdun mods to one of the first A60 amps I tried. To be honest it's Roberts mods on PFM that have stood the test of time and listening. I did try the R50 mods and did not get anything like the claimed improvements so I reversed the the mod. Not worth it in my opinion but that is just my experience.
Click to expand...

I certainly wouldn't expect it to have anything like the claimed effect
 
graham-r said:
Could you expand a little on this please - I was going to add it to my modified A60 PA PCB..... but I may not !
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There's no reason to think it would have a positive effect at the end of the day... There is already thermal compensation, it's just not done in the most conventional manner with a Vbe multiplier. I often add a capacitor between the driver bases in my designs, as do many others, to make sure there is a good low impedance between them and that parasitic capacitance's etc of both devices can be charged/discharged as quickly and equally as possible, this is in conjunction with the usual Vbe multiplier. It can sometimes make a small difference .
As I said up thread, a cap across R50 would be vastly more effective than this "R50 mod" but it needs properly testing in real life and changes in frequency compensation may be required. You may wish to allow space for such a capacitor in your layout but I strongly recommend against trying it without the test gear and knowledge to be able to prevent damage if it is problematic, and whilst under optimisation, and to see oscillation, peaking, ringing etc and re-compensate to get around this.

Personally I have no incentive to do anything whatsoever with A60's as unfortunately the average enthusiast decides to spend money based on resale value and not on results...
 
Thanks for the considered reply - I must admit I am loathe to make too many changes to the actual circuit to avoid changing the character of the amp.

Using better quality components in certain places, like the multi-turn trimpot, or using an ALPS vol pot, for example, that seems logical.

I can understand not having incentive for the A60 (etc) if this is how you make your living, but as this is the DIY section there is more leeway for messing about a bit.
 
There's no sound quality gains to be had from using multi turn trimmers. Alps vol pot will mainly be a big help in tracking accuracy between channels but I would not expect much, if any, sound quality improvement.
 
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