Question Repair or replace faulty amp?

[clevejon]

My 2004 vintage Musical Fidelity kW500 integrated amp stopped working recently and has been in the workshop of the UK service agent for assessment.
The repair cost is estimated at around £500 for parts and labour. The original cost of the new amp was about £4,000 back in 2004.

My question is, would it be worth repairing the original unit or should I cut my losses and reinvest the £500 in a new amp?

If buying a new amp, any suggestions for a budget of £3k to £5k?

My system:
NAIM NDX2 music streamer
Lenco GL75 turntable (Audiomods Series 5 tonearm, Lyra Delos MC cartridge)
Ming Da MC Phono 2006, valve based phono amp
Lector CDP 603 valve CD player
Arcam A85 integrated amp (just a temporary replacement for the MF kW500)
Troel Gravesen Illumina-66 DIY floorstanding speakers (4 ohms nominal impedance)

 

[simon g]

Get it repaired. If you don't then its value is parts only. If repaired, you could either sell or trade in, if you fancy a change. Loads of choices out there.

 

[wHIZZY]

Just out of interest was the service agent Henley and did they tell you what the problem was and what work needed to be done?

 

[Mr Kandid]

That would be a big cash drop if you’ve enjoyed the amp up until tired then I’d give it a new lease of life and if it doesn’t float your boat then sell on as fully serviced.
The whole point of buying repairable and serviceable kit is that you can.

 

[clevejon]

Just out of interest was the service agent Henley and did they tell you what the problem was and what work needed to be done?

Henley Audio put me on to Deco Audio in Aylesbury who are the UK authorised service agents for MF and have access to the schematics for the amps etc. Yes, I did get a fairly detailed email on what the problem seems to be. I can post it if there is interest on this forum.

 

[clevejon]

That would be a big cash drop if you’ve enjoyed the amp up until tired then I’d give it a new lease of life and if it doesn’t float your boat then sell on as fully serviced.
The whole point of buying repairable and serviceable kit is that you can.

Any views on what the resell value of my amp might be? I have found that good quality hifi holds its value reasonably well, so I would guess about half of what it cost me less the repair costs, so possibly £1,500 recoverable (£4,000 original, so £2,000 resale minus £500 repair cost)? Does that seem realistic?

 

[mnky]

Henley Audio put me on to Deco Audio in Aylesbury who are the UK authorised service agents for MF and have access to the schematics for the amps etc. Yes, I did get a fairly detailed email on what the problem seems to be. I can post it if there is interest on this forum

I was wondering what the problem was.

It would be of interest if that's ok with you.

Ger

 

[clevejon]

Get it repaired. If you don't then its value is parts only. If repaired, you could either sell or trade in, if you fancy a change. Loads of choices out there.

I am considering the current equivalent of the old kW500, the MF M6si500. I have seen some good reviews and I liked the transparent sound and detail of my old amp. I have some other concerns about repairing the old amp as it has had some mods over the years, so is a little bit "non specification" now.

 

[audio_PHIL_e]

You've had it a while and presumably like it. If you replaced it, you'd need £4k x (inflation since 2004) x (correction factor for similarly capable gear at that price point) which I think is > your proposed repair bill. Unless I was looking for an excuse to replace, I'd fix it. Other peoples' comments about making it fit for resale also apply.

 

[clevejon]

I was wondering what the problem was.

It would be of interest if that's ok with you.

Ger

Here is an edited version of what the service person reported back to me:

"...one channel has gone bang, in a big way, as I say, not surprising on a Semiconductor Amp of such ‘Power’....

...I have powered the faulty channel with a Bench Power Supply and I did get what I think are the right Voltages and even some semblance of Signal getting its way toward the O/P Transistors (which having failed Short-Circuit I have removed).

As to what caused this?
I don’t think it was caused by trying to drive 4 OHM Speakers. The Instruction Book ( https://www.musicalfidelity.com/uploads/manuals/English/kW500.pdf ) gives in the Specifications a Power Output figure measured at 4 OHMS so it is designed to cope with such a Load.
It’s a piece of electronic equipment. It is going to fail at some point. It’s also a Transistor Amplifier, so in my experience, when it fails it will do so spectacularly (!). One can never tell when it’s going to fail, The failed devices in your Amp look just like new, they haven’t ‘exploded’ (like they sometimes can) but they have become internally Short-Circuit (taking several passive components such as Resistors etc etc with them).
Thankfully the Protection circuit must have activated quickly enough to save your Speakers."

 

[mnky]

It is a bit of a beast ....I'm assuming six maybe 8 power MOSFETs to replace with assorted resistors etc. ...

If the repair comes with warranty....I'd go for the repair.....

 

[Sotosound]

James at Deco is an excellent engineer.

I'd also want an opinion regarding whether or not the other channel is likely to suffer the same fate, as it's the same age and has had the same usage.

Agree about needing a warranty but I can't see Deco ever not warranting their work. It would wreck their reputation.

Here is their "Repairs" web page.

http://decoaudio.com/deco_audio_repairs.html

 

[mnky]

Yeah. I assumed there'd be warranty.....but best check ....

 

[graham67]

£500 wont buy you much nowadays so repair and enjoy.

 

[clevejon]

It is a bit of a beast ....I'm assuming six maybe 8 power MOSFETs to replace with assorted resistors etc. ...

If the repair comes with warranty....I'd go for the repair.....

Good point about the warranty. I will go back and check with James. Also, need to check if the warranty is transferable (is that the norm?) in the case that I decide to repair and sell on.

 

[clevejon]

James at Deco is an excellent engineer.

I'd also want an opinion regarding whether or not the other channel is likely to suffer the same fate, as it's the same age and has had the same usage.

Agree about needing a warranty but I can't see Deco ever not warranting their work. It would wreck their reputation.

Here is their "Repairs" web page.

http://decoaudio.com/deco_audio_repairs.html

I got the impression from James' initial diagnosis and commentary that the lifetime of transistor components is a bit of an imponderable? Of course, assuming that the equipment is not being misused in some way. But then again, I am not an electronics engineer...

 

[clevejon]

£500 wont buy you much nowadays so repair and enjoy.

The Musical Fidelity M6si500 is list priced at £4,099 although you can find it advertised a couple of places at £3,999. One online reseller (Audio Affair) also has a "discount voucher" for an additional 5% off. So I am probably going to go for the new amp and try selling the old one after repair, if it comes with a guarantee as discussed in other posts here.

 

[Mr Kandid]

£500 investment keep or sell as working or it’s a big door stop.

 

[clevejon]

Yeah. I assumed there'd be warranty.....but best check ....

I will!!!

You've had it a while and presumably like it. If you replaced it, you'd need £4k x (inflation since 2004) x (correction factor for similarly capable gear at that price point) which I think is > your proposed repair bill. Unless I was looking for an excuse to replace, I'd fix it. Other peoples' comments about making it fit for resale also apply.

I am edging towards repair and resell the old amp and then buy a new MF amp and probably the current MF6si 500 watts per channel as I liked the old one so much. I do realise that the sound would not necessarily be the same with the contemporary model but the reviews I have read online are pretty positive. I think the reseller Senso down in Truro carry MF products, if I feel an audition would be sensible (well, it would be sensible...but being sensible is very time consuming....).

 

[Sotosound]

I will!!!

I am edging towards repair and resell the old amp and then buy a new MF amp and probably the current MF6si 500 watts per channel as I liked the old one so much. I do realise that the sound would not necessarily be the same with the contemporary model but the reviews I have read online are pretty positive. I think the reseller Senso down in Truro carry MF products, if I feel an audition would be sensible (well, it would be sensible...but being sensible is very time consuming....).

I have a Croft pre-power combo that I really like, and the only circumstances under which I would consider replacing it would be if it were beyond repair or if it were no longer meeting my needs.

Would it be worth auditioning the new against the old before making a decision?