faulty Musical Fidelity B1

[TecdiverUK]

I have an old Musical Fidelity B1 amp, which I've owned for about 20 years.

For the last few years it's sat on a shelf unused, but I recently decided to dust it off and try it out, but was disappointed to find that there is now a bad 'crackle' on the left channel.

I'm not an electronics expert but would like to get it working properly for a sensible price as I'm currently on a bit of a budget.

Is there someone willing to test and repair it for me?

I believe that it's also sensible to upgrade some with polypropylene capacitors etc. at the same time and use metal film resistors as required (if any are blown).

I live in West Sussex, not far from London Gatwick Airport, so London is easy to get to, as is the Sussex / Kent / Surrey area.

 

[Puffin]

Is it just the volume pot? Have you tried turning it fully clockwise and anticlockwise with the amp off. When you switch the amp on you can still twiddle it and you may find that at some point the crackle may lessen or go away. If it does stop the crackle it may need some switch cleaner (perhaps as a temporary solution) or a new/replacement volume pot.

Whereabouts in W.Sussex are you?

 

[TecdiverUK]

Hi,

I live in East Grinstead. PM me and we can swap phone numbers.

BTW I haven't yet plugged in and tried the amp myself.

It was tested by Future Audio last week
when they installed a new cartridge in my record deck and set the deck up. They reported the crackling sound on the left channel.

 

[Puffin]

I sent you a PM earlier today and I also thought that I had posted a reply to your post #3, but looking now it seems it didn't send. I am just into W.Sussex on the borders with Surrey & Hants. I used to have an MF A1 and now regret having got rid of it. That had a noisy volume pot. Here is a link to a site about the A1 and a lot if the ancillaries may apply to the B1.

Musical Fidelity A1 › Modifications

I have built many amps over the years, Class A, Class D, Mosfet and have tweaked many components - Dacs and buffers etc.
Rob.

 

[TecdiverUK]

Repair to Musical Fidelity B1 amp

Hi Rob,

Sorry for the delay in responding.

I'm currently travelling and so can't re-test the amp at home at the moment, but I'll make time later this month to do so and try your suggestions.

Although I do have a basic understanding of the issues and happy to wield a soldering iron, I'm not an electronics expert, so appreciate all assistance and advice.

My understanding from Mark Hennessy is that the B1 actually had a better pre-amp than an (unmodified) A1, so would like to get it working and as it's a B class amp, generates much less heat (which is important to me as it's in a reasonably tight enclosure with some airflow.

If it's not be too difficult and worthwhile I'd also consider upgrading some of the components to improve the amp. I believe that replacing some of the capacitors and even Op-Amps to newer generation audiophile quality components can make a significant improvement.

If you have time I will call you later today.