X-Can v3, strange noises when switching on and off.

[jots]

Well, first post and like most new members it's because I may have a problem.
I've recently bought the x-can v3 unit, primarily because of reading this forum and it's testimony to upgrading this unit, additionally I like Class A amplification, in fact use nothing else but. My intention was/is to upgrade the capacitors and valves available from Mike, However strange noises can be heard through the headphones when powering up and turning the unit off.
At switch on with the volume set at zero and not wearing the headphones a gentle but very audible 'whoosh' sound can be heard from my headphones (both channels), additionally switching off, again not wearing the headphones and the volume at zero a loud noise not too dissimilar to a shortwave radio being tuned in with a loud crackling sound can be heard (both channels) which diminishes in volume over five or six seconds.
Knowing absolutely nothing about electronics can anyone help identify the cause of these noises ?. All capacitors look fine to the eye although I appreciate this means little, there are no burns to the pcb,  everything appears as it should to the untrained eye.
I really don't want to splash out on new capacitors and valves if the problem is elsewhere and would negate any upgrade. Transistors, diodes, capacitors, valves, resistors are terms I know but really are double dutch to me, I can solder and swap like for like, what they do within a circuit I leave to the experts.
I, as anyone else with a problem, would be grateful for any assistance in identifying the problem area. I've searched the forum and can't find a similar scenario, then again I could be looking in the wrong place. Thanks for your time reading this post.

[Deleted]

Semiconductors don't cause symptoms like that and then come good. Neither do resistors, so the most obvious choice is aging valves.
The larger value electrolytic capacitors can also lose capacitance due to aging, especially where they are near sources of heat such as valves,
but are highly unlikely to cause those symptoms.
Personally, I would go with your original thought of Mike's upgrade kit with new valves.
You can also remove the input coupling capacitors and replace the output coupling capacitors as Mike recommends.

Alex

[jots]

A sincere thank you for your very speedy and early morning reply. I shall contact Mike and order the capacitor upgrade and new valves tomorrow all things being well. The upgrades that are well documented look pretty straight forward, so hopefully all will go well in the not too distant future. Many thanks once again, your time and advice is really appreciated.

John

[jots]

As an update to my previous post :-
I received the capacitor and valve upgrade from Mike in very quick time and had everything fitted that same afternoon. Initial impression was one of a thinness to the sound, leading edges of instruments being heard but without timbre, especially cymbals where the 'shimmer' on known music was absent. A couple of hours in and things started to settle down a little. I now have 50 hours on the upgraded unit, listening after approx. every 8-10 hours of running the amp on a loop of music. Each listening period has surprised me, the change has been quite dramatic, instruments and voices have all snapped into place really well.
I'm always aware of expectation bias, but after the initial listening I had little or no expectation of such improvement, 'burn in' was an audiotomfoolery term, burn in has occurred (I think) and I couldn't be happier - honestly.
Because of the faults originally with the unit, I don't believe that I knew how the unit would have sounded from the manufacturers. I can say that at the price for the unit and upgrade performed I am more than happy with the sound and if demonstrated in a shop at that price would have taken it home without hesitation and chuckled knowing I'd bagged a bargain.
Thanks to Alex for replying to my original question and thanks to Mike for his speed of service and years of listening that has resulted in this upgrade. One happy chappy.

John

[PinkFloyd]

Hi John,

I am so happy that you are enjoying the music again and thank you for your valued feedback, it's most appreciated.

Best regards,

Mike.

[mikey]

I also experienced these concerning sound when switching on the amp. I thought this was normal and so just tried to ensure I had the headphones unplugged before switching on/off the amp. I do forget sometimes and it shocks and terrifies me when this happens and think about my precious headphones(and my ears).

I guess is time to order some new valves from Mike.

Just wanted to say how great Mike is when he helped out with my problem recently with my Little Pinkie. A big thank you to Mike.

[PinkFloyd]

Jul 21, 2016 12:36:39 GMT mikey said:

I also experienced these concerning sound when switching on the amp. I thought this was normal and so just tried to ensure I had the headphones unplugged before switching on/off the amp. I do forget sometimes and it shocks and terrifies me when this happens and think about my precious headphones(and my ears).

I guess is time to order some new valves from Mike.

Just wanted to say how great Mike is when he helped out with my problem recently with my Little Pinkie. A big thank you to Mike.

Hi Mikey,

I'm not at home (away for a few days) but will reply as soon as I return.

Best regards,

Mike.