Hi-Fi help

[bojangle]

I have a Arcam Alpha 5 Plus amp and the other day while listening to some music 'rather' loud!!! The amp stopped working, ok maybe a thermal cutout i thought, unplugged it left it for a while....plugged it back in nothing!!

So next step take cover off and see if anything obvious jumps out at me......ahh a blown mains input fuse, so off down the local spark shop and get a new fuse, thought i'd get a spare just in case!!

So this morning i decide to replace the fuse, plugged it back in and....POP......grrrrr. I would like to ask for some help at this point before i blow the spare fuse as well.

Now before anyone asks the obvious questions.......the fuse was replaced like for like (based on the marking and details on the fuse!)

I've never had the problem before.

I can't see anything else visibly wrong.

It is possible i was running the amp waaay too flat out.

So any help on this matter......is it dead? :cry:

 

[legrandefromage]

Its off to the repair shop as their is nothing you or I could fix.

You may have blown an output transistor which is the most common fault.

 

[bojangle]

:cry:
Is it worth repairing? I'll guess i'll phone round a few places, the trouble is i know what answer i'm gonna get on the phone "not sure without looking at it mate! best bring it in so i can charge you £20 to say it's f**ked"

 

[legrandefromage]

:cry:
Is it worth repairing? I'll guess i'll phone round a few places, the trouble is i know what answer i'm gonna get on the phone "not sure without looking at it mate! best bring it in so i can charge you £20 to say it's f**ked"

they cant quote without virtually repairing it.

check out used prices first.

 

[bojangle]

ok lets look at this another way,

I have 2x floorstanders = 130w long term/190w short term
and 2x shelf = 40w long term/ 60w short term.

Fairly often the amp is running close to max with all four speakers running, but more often than not it just the floorstanders.

So my question is this was my amp a bit feeble for the speakers, could this have caused the failure.

Actually in the middle of writing this post i had a quick check to find out the output of the amp....and..gulp.....its 40W per channel!! i could have sworn it was more than this when i got it!!

anyway i digress, it was purchased off the bay and i was thinking of putting it back on there as spares and repair and getting something else.

getting back to my first question can anybody recommend the best size amp to go for! I'm not really into hi-fi in a big way so have never took the time to understand about matching amp and watts etc etc,

If you want to get precise and recommend an amp it needs to be black and be able to switch the speakers on and off (or at least one pair)

 

[gump]

umm how did you connect all four speakers?

Oh, don't worry about the watts on amp vs speakers, thats a whole different issue.. and not generally a cause for concern

 

[bojangle]

It's a four channel amp so the speakers all had their own channels!

I just wondered if the speakers were drawing too much power and that caused the amp to cook! it was very very hot went it went!

 

[sic_nick]

The impedance of the speakers it what pulls the power from the amp and can make it work too hard, you should have speakers that can take more watts than the amp can drive to prevent distortion and blowing speaker drivers.

 

[Skeelsie]

It may have four sets of binding posts/speaker outs but it's not a four channel amp.

If you are running two pairs of speakers it will regularly powering a load that is too little impedance for the amplifier to cope with, the Alpha 5 has never been a power monster so it has done well to last this far. I'm sure if it had been part of the newer breed of Arcam gear it would have been toast very quickly.

Really the lowest impedance that amplifier will be happy with is 4ohms and with two sets of speakers you could be showing it a load as little as 1ohm at certain frequencies.

As LGF says you've probably blown the output fets/transistors.

It can be an easy fix for a DIY'er but if there are any brown bits on the printed circuit board it gets a lot trickier to repair.




If you want high power without Hi-Fi prices I'd look at some pro audio equipment, Behringer etc. It'll sound pretty much the same and have way more headroom than anything sub £500.



This would also drive four speakers pretty well.

http://www.richersounds.com/showclearan ... x1016.html

http://www.richersounds.com/showclearan ... sx919.html

http://www.richersounds.com/showclearan ... 08sre.html

 

[6.5x55]

Agreed. If it went off with a very sharp BANG or a CRACK, you could be looking at transistors. You can easily tell because the bang is the core of the transistor blowing out. Your looking for large vertical black square things normally on three legs and attached to a large heatsink.