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Old 10th December 2006, 02:21 PM   #1
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Default Musical Fidelity X-A1 Modification

Hi All
Thought i'd chance a question....

I have a Musical Fidelity X-A1 that has given great service for the last 5 years, but after listening to my friends Exposure amp, I want to inject a bit more life into the mix.

Has anybody set about one of these creatures? What mods make sense , and are there any recommendations other than getting another amp..... What about capacitor upgrades? What about anything upgrades!!!

I am easy with a soldering iron, so no mod too big
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Old 10th December 2006, 02:28 PM   #2
Zen Mod is offline Zen Mod  Serbia
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Old 10th December 2006, 05:01 PM   #3
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Close but no cigar, thats the A1, not the X-A1. Thanks for helping.
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Old 13th December 2006, 08:39 AM   #4
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OK! not a resounding success......

I have had a look inside, the unit, and it has cheapo caps, and ceramics. What are the best reasonable capacitors for the price, and also where can I get them in the UK, or easily through the web please?

Does anyone have a component list to hand also, otherwise, I will compose one....
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Old 31st December 2006, 12:25 PM   #5
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Update, and advice needed.

1. Replaced elctrolytics with Blackgates, that brought about an immediate clarity to the sound. Solid bass, and better resolution.

2. Replaced all 47pf ceramics with RS 113-241 Polystyrene axial capacitor, 47pF 160Vdc that introduced serious distortion. Should I have used something else? If so please tell me what. Ceramics put back in.

3. Placed a few WIMA FKP2 radial polyprop cap,220,330,470pF 100Vdc in place of ceramics. Sound is much clearer, but there seems to be a slight hardening in the upper frequencies. I have not replaced them all, as I am concerned on an imbalance. What would you advise to replace with?

4. There is an SEP BR104 Bridge rectifier. What would you replace this with?

I am having much fun with this, so am looking to go as far as I can.

Any help much appreciated.

Adam
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Old 31st December 2006, 12:29 PM   #6
Zen Mod is offline Zen Mod  Serbia
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it will be helpfull if you can find schmtc and show it,so we can see where and which part you want to tweek........

sorry for wrong link
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Old 31st December 2006, 12:36 PM   #7
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no worries. MF are well known for lack of circuit diagrams. would pictures help?
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Old 31st December 2006, 01:12 PM   #8
AndrewT is offline AndrewT  Scotland
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Hi,
ceramics have very variable characteristics.
Ceramics in general cannot be avoided for VHF circuits.
Some ceramics perform VERY well in audio circuits.
NP0 (=C0G) ceramics have excellent stability and accuracy. Their only downfall (that I am aware of) is their variation with applied voltage. This makes them supreme above all else for bypass duty where they see a constant voltage while operating.

They can also be used in the audio signal transfer side of the circuit if selected appropriately.
I suspect your 47pF were NP0 and that they had been correctly chosen for their duty. MF do not usually make mistakes like that.

The PP substitute may benefit from a parallel decoupling using a smaller cap under the PCB. Either a small PP or a NP0 ceramic. Two different di-electrics may return balance.

Have a look at your feedback loop and at your input filter. They can often be improved.
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