Digital amplifier repair (Flying Mole) - help needed

[Dan B]

Hi

I have 2 x Flying Mole DAD M100 Pro HT class D monoblock amps which I am using to power my PMC TB2+ speakers. One of the amps has now developed a fault: it distorts quite severely, with more distortion the higher the input level. I have tested all the other items in the setup and it is definitely the amp that is the problem. It appears Flying Mole are no longer in business and not responding to email, and - despite lots of effort - I'm struggling to find anyone who will take a look at it. These amps don't seem to be available any more, so replacing it doesn't seem to be an option. Meaning repair, or replacing both monoblocks with something else(which I can't really afford - especially given how good the Flying Moles were for the money).

Can you recommend someone who might be able to help? I gather there's further complication: the components on the FM amps do not appear to be labelled, so even if I am able to identify the faulty components it may be hard to know what to replace them with....!

I am based in London.

Many thanks,

Dan

[Kwackman]

You could try PMC to see if they know of anyone.

http://www.pmc-speakers.com/

[Hugh Robjohns]

One of the amps has now developed a fault: it distorts quite severely, with more distortion the higher the input level.

How odd! I've just been helping a friend trouble shoot his four year old TB2As, one of which was distorting in a similar way to yours, and identified the Flying Mole amp as the cause. Discussing it with PMC today I was told that they don't have any serviceable replacements and can't offer a repair, so my friend has decided to upgrade to the DS001 amps (which are twice as powerful) instead.

The best advice I can offer is to get in touch with Ian Downs at PMC (ian at promonitor dot co dot uk) and see if he has a working trade-in Flyng Mole you could purchase, or maybe offer you an upgrade to PMC's own DS001s.

Hugh

[Dan B]

Thanks.

I actually emailed PMC earlier today, so I'll see what they say. I'm afraid I can't afford to move up to the DS-001, much as I'd like too.

At a stretch, I could afford to replace one of the Moles with an identical one - but there don't seem to be many of them around for sale (new or s/h).

My only other option at the moment is to dust off my old Samson Servo 260 (argh) or - slightly better - an ageing Panasonic A400 (with grounding issues). I've been somewhat spoiled by the Moles (which I love - picked up new on an amazing deal - year end close out) and I fear there's little to be had for the price I paid that would hold a candle to them...

[Dan B]

P.S. Hugh - might your friend have a spare Flying Mole then, since he's replacing his? Or did both go?

[Hugh Robjohns]

He returned them to PMC as part of the upgrade deal.

hugh

[James Perrett]

Since the forum title includes DIY, one thing I would think about would be to replace the amplifier module with one of the Hypex UCD modules. Of course, this depends on whether it is possible to separate the power supply from the amplifier and on the power supply having a suitable voltage but it may not be out of the question to also replace the power supply with a Hypex supply.

James.

[forumuser695516]

Since the forum title includes DIY, one thing I would think about would be to replace the amplifier module with one of the Hypex UCD modules. Of course, this depends on whether it is possible to separate the power supply from the amplifier and on the power supply having a suitable voltage but it may not be out of the question to also replace the power supply with a Hypex supply.

James.

I think it may have been Hugh that hinted that the latest PMC amp modules may contain Class D Hypex gubbins anyway. And even if they don't.. Hypex are still great amps. Albeit in module form (meaning you build the rest of it yourself, but its very easy).
You can make a stereo 200 watt Hypex amp for around the same cost as a single (mono) PMC amp. I did And i've been perfectly pleased with it.

[Kwackman]

For the first time in ages there's a pair of Flying Moles on eBay- although one os described as faulty.

Strange coincidence.......

[ef37a]

It is of little comfort to the OP I know but, this is the price you pay for "clever" technology.

It can be impossible to get repaired. I well remember the introduction of SMPSUs in TVs and later VCR. Many hours were often spent changing a score of components (many of which were afterthought "bodges" on the print side of the pcb!) only to have the thing burn up on switch on (and yes Cclogs, we used variacs and lamps!)How many SMPS's failed in say 1000 rental VCRs? Scores a year*. How many 50Hz traffs? Essentially none. A "digital" power amp is really just a very fast SMPSU with a speaker as the load!

I will agree that SMPUs as used for laptop supplies, monitor power etc are now very mature and reliable technology (which is just as well because nobody coulds mend t'buggers!)but I have long felt that those that profit from the sale of expensive electronic equipment should be made to make service provision of some sort.

*Did NOT like thunderstorms!

Dave.

[James Perrett]

That's the thing with the Hypex amps Dave - if they give problems then I (and probably quite a few others) know where to find the designer

James.

[ef37a]

That's the thing with the Hypex amps Dave - if they give problems then I (and probably quite a few others) know where to find the designer

James.

Well that's fine for "The boys in the know" but I want a decent service system for everyone.
We cannot simply go on making new stuff badly when the old stuff breaks.

Dave.

[dmills]

He is not exactly hard to find, but I agree and what I would like is a schematic actually in the supplied user documentation (For everything!).
The user does not need to understand it, but it makes the thing repairable by any competent tech.

And as for the IP argument, there is usually nothing that a competent reverse engineering team can not figure out quickly anyway.

It used to be the case that a lot of older hifi gear actually had a schematic glued to the inside of the case, made repairs very straight forward.

Regards, Dan.

[Folderol]

I think it was Sony that was the first to not provide schematics. They were certainly the first to not give information to service departments that were not their official franchises. Now it's spreading into industrial kit. A lot of the modern machinery has no service information, or deliberately misses out critical stuff so on-site engineers can only do basic repairs.

One Manufacturing Bugger Off-er has nice error codes for all the system faults, but won't tell you what they are

[ef37a]

I entirely agree with you Will. I too remember schematics inside equipment or foldout sheets in the instruction handbook. Geez! Nagra used to supply a small poly bag of components!

There is one small problem that I see. My last employer spent a lot of time,midnight oil, fags tea and bad language getting voicing circuits right. They are still a small company and fear all that work, if in the public domain, would be copied.

My personal view is that the more "professional" approach of giving out circuits to people who can show a genuine need is the best policy. The likes of Bellringers have the wherewithall to rip anybodies design, maps or no maps.

Dave.

[Jack Ruston]

Dan, I've just ordered an amp from classdaudio.com. It was 600 dollars and I'm told by a reliable source that it's 'amazing'. I will check it out and let you know. If it's good, it might be a worthwhile solution.

J

[dmills]

Dave,
given a working amplifier, do you really think it would take me (or any halfways competent analogue 'tronics type) more then about a day or 3 to rev. eng. the voicing networks.

Getting them empirically right might be tediously tweaky, but the netwoks themselves are rarely anything massively complex.

And yea, the usual suspects have plenty of analogue expertise on hand if they need it.

Regards, Dan.

[. . . Delete This User . . .]

i'm quite impressed by some offerings from Ground sound

http://www.groundsound.com/

[ef37a]

Dave,
given a working amplifier, do you really think it would take me (or any halfways competent analogue 'tronics type) more then about a day or 3 to rev. eng. the voicing networks.

Getting them empirically right might be tediously tweaky, but the netwoks themselves are rarely anything massively complex.

And yea, the usual suspects have plenty of analogue expertise on hand if they need it.

Regards, Dan.

No Dan I do not think that. My point is that the company PERCEPTION is that circuits will be copied and that is why they don't stick a schematic in every cab.

My personal view is that circuit information should be readily available and for other reasons than just the service man's convienience.

And if a "certain" company wants to rip the works, at least they will have to buy an amp first! But then it has long been page one, book one of the electronics designers bible, "See how the other buggers did it first".

Dave.

[Martin Walker]

Dan, I've just ordered an amp from classdaudio.com. It was 600 dollars and I'm told by a reliable source that it's 'amazing'. I will check it out and let you know. If it's good, it might be a worthwhile solution.

J

That sounds most interesting Jack - looking forward to your feedback

Martin

[Dan B]

Indeed! Let us know how it works out. I take it that it's this one:

http://classdaudio.com/products/complete-amplifiers-1/magic-garden-mastering-amplifier.html

[Martin Walker]

It’s certainly $600, but what an odd design!

Completely blank front panel and gain controls on the rear

Martin

[James Perrett]

I guess that they expect most users to have a mixing desk or monitor controller so that the gain controls are just there to match the amp sensitivity to whatever else you are using. Some of us use amps with no gain controls - although I've made a small attenuator box to go inline for my monitor amp.

James.

[Dan B]

I guess so. Still, a pain adjusting the trims on the back of a rack. At least it's a "set once and forget" thing. I'm using a hi fi pre-amp with my Moles (discontinued s/h Cambridge Audio C500 - probably sacrilegious but I was struggling to fund - or justify - paying a lot more for a volume control).

The ebay Moles went for £430 odd including postage. And only one of the pair was working properly. I wasn't prepared to stretch to that: I paid less than that for a brand new pair. Since I actually have 4 Moles (only 3 working) and 2 sets of PMC TB2s's with 2 CA C500 pre's (studio set and live room/living room set). So I suspect I'll keep the third Mole as a spare (I gather quite a few class d amps have reliability issues in the longer term) and look for a new amp.

I'd be interested to hear about the $600 one above (probably the best part of £600 once import duty, VAT, shipping and handling all accounted for). Perhaps even more tempting (based on favourable reviews - e.g. http://www.audiocircle.com/index.php?topic=76400.0 - and low price) is this: http://classdaudio.com/index.php/120w-x-2-240w-x-1-amp-power-supply-transformer.html

Any thoughts / comments?

I'm struggling to imagine that any traditional class A/B or tube amp offers as much bang for buck, but do let me know if I'm wrong here.

[forumuser695516]

^ Thats partly why I went with Hypex. They are dutch, so no import duty/taxes to worry about. And from what I could gather at the time, they seemed to have about the best reputation going for Class D kit. Which in turn also means they are not the cheapest. But still a bloody good amp for the money.
I guess it could self detonate some time, but so far so good (1.5 years or so)