Class D Amps

[Mykesbass]

Lots of interesting Class D amps around now, several sounding like the sort of thing I want. However, I had an early Yamaha BB500 (which I really liked) that one day just died on me. It was a few years old (4 may be 5) but hadn't been used much. I then found out that amp techs didn't stand a chance of fixing it as the technology was very different from what they worked with.

So, two questions, How long have you been running a class D amp for? Have you found anyone who can repair them?

Thanks,
Mike

[Mr. Foxen]

It is probably more construction methods that make it hard to fix, everything is surface mount an modular, so to fix, just replace whole relevant module. If you want a long term amp, get a handwired valve one on turrets.

[Mykesbass]

[quote name='Mr. Foxen' post='1312129' date='Jul 21 2011, 10:31 PM']It is probably more construction methods that make it hard to fix, everything is surface mount an modular, so to fix, just replace whole relevant module. If you want a long term amp, get a handwired valve one on turrets.[/quote]

I think you've been paying attention to previous posts of mine! Yes I would love to. Not hand wired, but I have been hankering after a Traynor for a while, seem like well priced amps, just that Thomann are the only "UK" dealer at the moment and aren't expecting stock for months! Been keeping a close eye on the f/s section as well. Just somehow the Class D route seems so much less hassle (if they work)!

[Mr. Foxen]

If you get a bust one and fix it up, you don't have to worry about reliability so much as you can fix it yourself (but need a gig backup).

[chris_b]

[quote name='Mykesbass' post='1312138' date='Jul 21 2011, 10:36 PM']....Just somehow the Class D route seems so much less hassle (if they work)!....[/quote]
Some Markbass, Genz and TC are D class and I haven't heard of any issues with those amps.

I had more trouble during my time with valve amps than I’ve had with SS and class D amps.

[Mr. Foxen]

How hard was the trouble to fix when it happens is the start point. Additional difficulty with new gear is that no-one is allowed to use good solder any more, except the military and stuff to go into space.

[Alec]

[quote name='chris_b' post='1312259' date='Jul 22 2011, 01:10 AM']Some Markbass, Genz and TC are D class and I haven't heard of any issues with those amps.

I had more trouble during my time with valve amps than I’ve had with SS and class D amps.[/quote]

The problem with the modern class D amps is their very complexity and density of components. This means that in most cases, when failures occur, all that can be done is to switch out and replace a whole board/module. Fine in principle, albeit potentially costly to the consumer, but you're stuffed a few years down the line when spares cease to be available.

Don't get me wrong, I'm a complete convert to the new, lightweight bass kit. But I *know*, that a fault in my old Trace combo would generally be a piece of cake to fix, as it's all discrete components, tidily laid out. Never did have a fault. But in kit like that, if you are capable of diagnosis & replacement, parts are typically in pennies. Compare this with £10s, if not £100s, for a replacement module in a modern amp.

[chrismuzz]

I've had my class D Markass f1 coming up to 3 years now and had no reliability issues. I'm afraid I can't comment on potential repair costs yet but I feel it'll be a while before I have to!

[flyfisher]

Its the way of the world these days; ever more complex, highly integrated technology. Wonderful stuff while it works but economically pointless to actually repair, except by simply replacing whole sub-assemblies.

If you have the tools, skills and knowledge, it can of course be done but only if you ignore the value of your time.

A pulley bearing siezed on my lawnmower last year. The replacement part was £110+vat, and that was without being fitted. The pully was made from two pressed-steel halves riveted together around the bearing. I didn't fancy shelling out £110+vat so repaired it myself.

I drilled out the rivets, separated the two pulley halves, accurately measured the bearing, found a replacement on the web, bought a couple of new bearings (£4.50 each), reassembled the pulley, pop-riveted the two halves together, re-fitted the pulley to the mower and, hey presto, it's been fine ever since.

Great - I saved well over £100. But imagine if I'd had to pay someone with decent workshop facilities to do the job for me?

Modern cars are the same. PCs are the same. In fact, pretty much all modern consumer electronics are the same. It's just modern life.

[chris_b]

[quote name='Alec' post='1312386' date='Jul 22 2011, 09:34 AM']....The problem with the modern class D amps is their very complexity and density of components. This means that in most cases, when failures occur, all that can be done is to switch out and replace a whole board/module. Fine in principle, albeit potentially costly to the consumer, but you're stuffed a few years down the line when spares cease to be available....[/quote]
So you won't buy anything unless you can repair it yourself or get it repaired for pennies?? With that approach most of us wouldn't buy anything! I certainly wouldn't own a car, TV, computer or fridge.

The last time I was there was before the start of class D, but when I went to amp repairer John Kelly's workshop, in Camden, he had a floor full of valve amps and very few SS amps.

As long as the trade off with class D is reliability then there is no problem.

Edited July 22, 2011 by chris_b

[BigRedX]

I own a Tech Soundsystems Black Cat amp (which used to belong to Warwickhunt). It's a valve/digital hybrid, with a point to point wired valve pre-amp and a 2x500W D-Class power amp.

Last year - after I'd been using it for 2½ years - for no apparent reason it stopped working due to a fuse blowing in the power amp section. Replacing the fuse just caused it to blow again so I got in touch with the manufacturer (now Techamp) and arranged to send it back to them to be fixed. By that time they had discontinued this particular model, but they were still able to fix it quickly (according to the repair invoice it was a couple of capacitors in the D-Class power amp that needed replacing). They also checked over the pre-amp section and made some repairs to that which means that the tone controls are now much more effective than when WH originally had it (so their apparent lack of effect was not supposed to be feature!)

The repair took about 2 weeks and cost around £200 (not bad for an amp which had a list price of over £2000) and most of that was shipping to and from Germany.

Based on this I am perfectly happy with Class-D amps. Apart form this one fault the the amp has worked reliably and Techamp have demonstrated that it is possible for them to repair the power amp without needing to swap out the whole module.

[BigRedX]

On the other hand I also have an Ashdown Superfly which is now a useless piece of crap and Ashdown don't want to know about getting it working properly.

[Mr. Foxen]

[quote name='chris_b' post='1312506' date='Jul 22 2011, 11:13 AM']The last time I was there was before the start of class D, but when I went to amp repairer John Kelly's workshop, in Camden, he had a floor full of valve amps and very few SS amps.[/quote]

That is because there was 40 years of valve amps and most broke SS goes in the bin right away. More of a construction method thing though. I have a discrete component SS power amp and whilst it is more stuff than a valve amp, it isn't super hard to work upon, unlike mini surface mount stuff, that I have no idea how to sort.

Edited July 22, 2011 by Mr. Foxen

[stevie]

But isn't Ashdown renowned for its wonderful after-sales service?

[BigRedX]

[quote name='stevie' post='1312557' date='Jul 22 2011, 11:47 AM']But isn't Ashdown renowned for its wonderful after-sales service?[/quote]
Maybe - unfortunately I haven't seen any evidence of this. I exchanged a couple of emails with their technical support but the general tone from Ashdown was one of disinterest.

The amp worked fine for about a year or so of light use and then after the first time I used it at an all-day rehearsal it developed the infamous Superfly whine and shortly after that developed a fault that means it won't power up about half the times I switch it on.

I would have invoked the "sale of goods" but it was bought from Sound Control who had gone into liquidation by the time the faults developed.

It was cheap and I've learnt my lesson and will be avoiding Ashdown gear in the future.

[bremen]

[quote name='flyfisher' post='1312445' date='Jul 22 2011, 10:24 AM']Its the way of the world these days; ever more complex, highly integrated technology. Wonderful stuff while it works but economically pointless to actually repair, except by simply replacing whole sub-assemblies...

Modern cars are the same. PCs are the same. In fact, pretty much all modern consumer electronics are the same. It's just modern life.[/quote]

What he said.

Class D should, in general, be more reliable than AB as there's so much less heat generated; heat is THE enemy when it comes to solid state electronics. It boils capacitors and stresses all those tiny little wires.

[Mr. Foxen]

[quote name='bremen' post='1312582' date='Jul 22 2011, 12:03 PM']Class D should, in general, be more reliable than AB as there's so much less heat generated; heat is THE enemy when it comes to solid state electronics. It boils capacitors and stresses all those tiny little wires.[/quote]

Big wires are the answer. And manly lead solder, for people smart enough to not lick the inside of their equipment.

[bremen]

[quote name='Mr. Foxen' post='1312606' date='Jul 22 2011, 12:21 PM']Big wires are the answer. And manly lead solder, for people smart enough to not lick the inside of their equipment.[/quote]

Big wires, mmm...I was referring to the tiny wires inside the semiconductors in this case though.

With you regarding Real Man's Solder. We have licence to use it here as we do medical electronics.

[stingrayPete1977]

[quote name='BigRedX' post='1312574' date='Jul 22 2011, 11:59 AM']Maybe - unfortunately I haven't seen any evidence of this. I exchanged a couple of emails with their technical support but the general tone from Ashdown was one of disinterest.

It was cheap and I've learnt my lesson and will be avoiding Ashdown gear in the future.[/quote]

Same here, unfortunatley mine was not cheap (very early English made ABM 300) not interested in the intermittent fault even though I was prepared to pay for a full diagnosis and repair to resolve it. Sold as spares or repair on ebay for £100 2 years ago and the Genz-Benz is doing nicely thankyou

[el borracho]

I had a yamaha bb500 as well. Went fine until one gig when it started repeatedly scrolling through all the presets. Interesting when it passed through distortion and fuzz!! Had to go back to yamaha to be repaired, fortunately under warranty. Since sold it on and the lad who bought it has had no problems since. I've gone back to valve/ss hybrid but had ongoing issues with the valve part. It is locally repairable though. Still tempted to try class d again - tc electronic maybe???

[JTUK]

I have an old SWR SM400 which run really really hot and doesn't need a fan.
The amp tech says it superbly made inside..albelt with a pre amp design quirk which he wouldn't do himself... but this is documented in the whole SWR/EDEN/Thundefunk personell roundabout.. and the components are top notch.

Only had one problem with it when it was knocked off stage..in 20 years..and cost pennies to repair by said tech.

You don't know what you have bought, mostly, until you need someone to look at them and then repair them.
Most of his work is valve gtr amps...and I don't think he would say that is especially down to age.... it is their initial build and design in the first place. Mention a few classic valve amps jobs and he will despair.

It is all very well swapping out boards but then we get into the problem as with cars these days...nobody fixes anything, they swap out the whole board or kit which can be very expensive..even though labour is likely to be less. They'll have you where they want you now.

[flyfisher]

[quote name='BigRedX' post='1312539' date='Jul 22 2011, 11:39 AM']I own a Tech Soundsystems Black Cat amp . . . .
Last year - after I'd been using it for 2½ years - for no apparent reason it stopped working . . . .
so I got in touch with the manufacturer (now Techamp) and arranged to send it back to them . . . .
they were still able to fix it quickly (according to the repair invoice it was a couple of capacitors . . . .
The repair took about 2 weeks and cost around £200 (not bad for an amp which had a list price of over £2000) and most of that was shipping to and from Germany.

Based on this I am perfectly happy with Class-D amps.[/quote]

Perfectly happy for a product to require return to the original manufacturer to diagnose and replace a problem with 50p's worth of components at a cost of 10% of the list price?

Hmm. Imagine having to send a £20k car back to the manufacturer to have a couple of lightbulbs changed at a cost of £2000.

But I'm not at all surprised about the story. A [u]manufacturer[/u] will always be able to repair stuff down to component level; they've designed and built the thing after all. But it will always be expensive, as the story proves.

C'est la vie.

[chrisd24]

My phil jones briefcase started making a popping cracking noise,as i brought it second-hand and it was out of warranty I took it to an amp tech who found out it was something in the digital power phase, he could probably fix it but phil jones wouldn't give him the schematics and do all their repairs in house so i have to send it to their distributor for repair..... apparently about £200 - £250 so I'm not sure if I'm even going to bother. The moral of the story is a lot of manufacturers wont give out these details so a lot of gear will ALWAYS have to go back to them for repair which will undoubtedly always be expensive.

[BigRedX]

[quote name='flyfisher' post='1313623' date='Jul 23 2011, 10:53 AM']Perfectly happy for a product to require return to the original manufacturer to diagnose and replace a problem with 50p's worth of components at a cost of 10% of the list price?

Hmm. Imagine having to send a £20k car back to the manufacturer to have a couple of lightbulbs changed at a cost of £2000.

But I'm not at all surprised about the story. A [u]manufacturer[/u] will always be able to repair stuff down to component level; they've designed and built the thing after all. But it will always be expensive, as the story proves.

C'est la vie.[/quote]
Looking at the invoice the parts and labour were around £70 and the rest was shipping the amp to and from Germany for the repair.

And you just have to look at all the horror stories on here about people taking their gear to what is supposed to be reputable tech and it coming back only partially fixed or worse. And then wonder why I wouldn't prefer to send my very expensive amp back to the manufacturer to be fixed.

From my PoV the manufacturer is the the best place to get a piece of gear like this fixed. Opening the amp up there are only two boards. The pre-amp which is all old-school point to point wiring with traditionally big components on tags and the digital board for the power and PSU which is a mass of densely pack surface mounted components. I was honestly expecting the fix (even from the manufacturer) to involve a complete swap out of this board which even if had been done locally would most likely have cost a lot more than £200.

In the end you pay your money and take your choice. I like the light weight and fantastic sound of my amp and if the cost of repair is a little more than a traditional SS or valve amp and involves a trip to Germany to achieve that's a compromise I'm prepared to accept. Even if I could have found someone in the UK that could fix the problem I doubt that the actual repair (parts and labour) would have been any cheaper and unless I was very lucky and they were local there would still have been shipping costs involved, and I wouldn't have had the piece of mind that a manufacturer repair has given me.

[lemmywinks]

[quote name='BigRedX' post='1312574' date='Jul 22 2011, 11:59 AM']Maybe - unfortunately I haven't seen any evidence of this. I exchanged a couple of emails with their technical support but the general tone from Ashdown was one of disinterest.

The amp worked fine for about a year or so of light use and then after the first time I used it at an all-day rehearsal it developed the infamous Superfly whine and shortly after that developed a fault that means it won't power up about half the times I switch it on.

I would have invoked the "sale of goods" but it was bought from Sound Control who had gone into liquidation by the time the faults developed.

It was cheap and I've learnt my lesson and will be avoiding Ashdown gear in the future.[/quote]


I got no reply when asking about the manufacturing faults on my Superfly. They were really responsive when i was asking questions about what cabs i could use with the 2x250w@4ohm configuration and whether it was safe to run a single cab, but weren't at all interested when the amp was cutting out on me and i had found out that whole batches were shipped faulty.

Fortunately i got mine from Gear4Music and they were great, taking it back and repairing it each time it went kaputt. It's worked fine since then and gets used pretty much daily.


It seems that Ashdown have great customer service as and when it suits them.