Jump to content
wayneyboy

D class Amps- advice

Recommended Posts

Hi guys -

recently got a d class amp - it’s the ebs Reidmar 750.  Had it checked out by a top tech locally as the guy i got it from said it cut out a few times.  All works fine now but he said some of these d class amps are so compact they can quite often over heat.  The fail safe in these amps are quite sensitive and so will cut out.  Noticed the fans are obviously quite small now as well.  I had a td 650 before which was very robust and now wondering if should switch back.  My td before was in a flight case and was more reassuring to be housed in there and less likely to get anything spilled over on it.  I think housing these d class amps will really restrict any air flow as don’t seem to be designed for it.  What are everyone’s thoughts ?  Appreciate any advice -

thanks guys 

Share this post


Link to post
Share on other sites

I’ve had a good few Class D amps, Ampeg (1) GK (2) Markbass (2) Ashdown (2) TC Electronic (2) and not had a problem with overheating with any of them. And I’ve used them in punk/heavy rock bands so not quiet music. However in all cases I’ve connected them to cabs that didn’t require running the amps at full pelt. Maybe the problems have come from cabs that weren’t up to the job so pushing the amps beyond their capabilities.

Share this post


Link to post
Share on other sites

Did this tech actually find a problem in this amp when he looked at it?

I have never had an SS or D class amp overheat and some of them have been run pretty hard.

Share this post


Link to post
Share on other sites

Is the fan working ok?

In general, class D should be fine. But the heat issue might be brand/model specific.
Techs cannot do much these day on the classD internals, it is just basically one PBA wrapped up in sheet metal :)

Share this post


Link to post
Share on other sites

Hi guys- he said he checked everything and it was all fine - said that some of these d class amps are not that repairable.  Guess will just have to wait and see or go back to an old school head and have a d class amp for back up maybe 

  • Confused 1

Share this post


Link to post
Share on other sites

The same could be said for anything. I’ve got an all valve amp, but I think my previous class D amp is a more reliable gigging amp (my valve amp needs a couple of new valves).

Share this post


Link to post
Share on other sites

Some of the class d amps are pretty much put it in the bin if anything goes wrong from what I’ve heard. The Ashdown RM500 EVO II which I have luckily isn’t one of them, another reason why I’m so pleased that I use Ashdown amps.

Share this post


Link to post
Share on other sites
On 29/11/2019 at 02:00, TonyMontana said:

Is the fan working ok?

In general, class D should be fine. But the heat issue might be brand/model specific.
Techs cannot do much these day on the classD internals, it is just basically one PBA wrapped up in sheet metal :)

This.

I did have an overheating problem on a very early Yamaha, but later class d from both Carvin and Genzler have never missed a beat (and the Genzler once got a hideous thrashing from a headline act that used it with the settings all wrong).

I took the Yamaha to 3 reputable techs and all said the same - nothing serviceable inside at all.

Share this post


Link to post
Share on other sites

I thought that due to their efficiency, class D amps don't produce a lot of heat? They don't need the same kind of cooling as other amps, part of the reason they can be that much smaller and lighter.

If there is an issue with the amp it's probably something other than temperature, I'd imagine.

Share this post


Link to post
Share on other sites
22 minutes ago, Jus Lukin said:

I thought that due to their efficiency, class D amps don't produce a lot of heat? They don't need the same kind of cooling as other amps, part of the reason they can be that much smaller and lighter.

If there is an issue with the amp it's probably something other than temperature, I'd imagine.

They don't produce enough heat, but can create enough to be a problem. My Yamaha used to be fine until the end of th enight. If I switched it off and then needed it (for heaven forbid an encore) then it wouldn't power back up.

Share this post


Link to post
Share on other sites

If you look at through the side slots on my Aguilar TH500 and AG700, you can see. . . . . . . virtually nothing! The ratio of stuff to space is about 50/50. Does anyone have any D class reliability issues these days? Not me. 

Anyone seen a pro touring PA system fail? Those FOH systems have been D class for many, many years. The PA companies who put together those systems wouldn't use anything unless it had the highest reliability imaginable. 

My valve amps were pretty good but the main ones, Marshall 100 watt and Mesa 400+, did fail on stage a couple of times over the years. I took my SS with a valve pre SVT3 to the repair shop for an MOT. The guy running the place said he'd never had one in for repair, but there were more than a dozen hire SVT's which had problems he needed to fix before they could go out again. SS amps hit a peak of reliability and it only got better with D class.

Electrical components will never have 100% reliability in anything but the failure rate these days is miniscule, but that's what backups are for. Who has used their backup amp because of a problem with their main amp? Again, I haven't. Is anyone old enough to remember the TV repair man coming to your house to fix those big wooden cased TV's? Or taking your broken radio to the repair shop? We are are at a time of the highest reliability in anything electrical.

So, to get back to the original comments. . . . . I don't see D class amps "regularly overheating". That's a generalisation that I don't believe.

Share this post


Link to post
Share on other sites

Appreciate all the comments and advice guys.   I have spoke to a few different people that are in the know and they said that some of the d class amps and basically machine made-  precision placed on the board and a lot are not repairable as no room to get to stuff etc.  I’m sure they are well tested and wouldn’t sell them if no good but is certainly food for thought for me.  I think most of the d class amps are meant to sit on the cab so that all the cut outs etc can allow the air flow.  I don’t really like the idea of rack mounting it for this reason but I also don’t like the idea of sitting it on top of the cab in a busy pub with beer flowing about.   Who knows .....

Share this post


Link to post
Share on other sites

I don’t get your point. Isn’t it the same no matter the amp?  I had a class d amp for about 6 years & had no issues at any of the gigs I played (or at any point). 
I’d give the amp a decent run & see how it goes. Did the seller say what caused it to cut out?  It could have been an intermittent short in a cable, such as speaker jack having a fray hit the shielding. 

Edited by xgsjx

Share this post


Link to post
Share on other sites

Class D amps use power amp modules that are bought in from manufacturers such as B&O/Icepower or Hypex. The technology is well established and it is just not worth amp designers attempting to design/build their own. Generally, they are not repairable. However, that doesn't mean that if they fail, the amp is scrap. Provided the preamp is fine, the power amp module can often be replaced.

  • Like 2

Share this post


Link to post
Share on other sites

Properly designed, any class of amp can be plenty reliable, but not well designed can affect the reliability of any class of amp. I have designed all types of amps, tube, solid state class AB and class D and haven't experienced any reliability issues (or unrepairable issues) on any of them.

While many power sections of class D amps are not easily or economically repairable, often replacing the power module is less expensive than the labor and parts on a conventional tube or class AB solid state amp. 

Generally, the preamp and supporting assemblies are easily repaired BY A QUALIFIED service tech. Now the problem I am seeing lately is that many who call themselves techs do not have the knowledge, qualifications or aptitude to properly repair this gear. That's not a technology problem, it's a service tech problem. We are losing the really good ones as they retire out of the industry, not too many coming in to take their place.

  • Like 2

Share this post


Link to post
Share on other sites

Yes that is indeed the problem finding a decent tech .

have to say I took out my Reidmar 750 on Saturday and It was so responsive and what a sound!  That in itself has softened the worry burden.  I think what I will do is always carry a spare in my lead bag which is not a bad thing anyway.   The only annoying thing is that it’s mainly designed for a single cab , like a 410, so not ideal for two neo 112’s which I also use.  My td 650 gave me all the options so now face a new dilemma lol 

oh the joys of being a bass player 😂

 

Share this post


Link to post
Share on other sites
1 hour ago, wayneyboy said:

The only annoying thing is that it’s mainly designed for a single cab , like a 410, so not ideal for two neo 112’s which I also use.  

? Huh - why’s that?

Share this post


Link to post
Share on other sites
3 hours ago, wayneyboy said:

The only annoying thing is that it’s mainly designed for a single cab , like a 410, so not ideal for two neo 112’s which I also use.  My td 650 gave me all the options so now face a new dilemma lol

If there is only one output on the amp you can daisy chain the cabs together. . . . . . . assuming your cabs have 2 sockets on each cab. If not you can probably get a cable made up that will do the job.

Share this post


Link to post
Share on other sites
46 minutes ago, chris_b said:

If there is only one output on the amp you can daisy chain the cabs together. . . . . . . assuming your cabs have 2 sockets on each cab. 

Or 2 sockets on one of the cabs.

Share this post


Link to post
Share on other sites
15 hours ago, agedhorse said:

Generally, the preamp and supporting assemblies are easily repaired BY A QUALIFIED service tech. Now the problem I am seeing lately is that many who call themselves techs do not have the knowledge, qualifications or aptitude to properly repair this gear. That's not a technology problem, it's a service tech problem. We are losing the really good ones as they retire out of the industry, not too many coming in to take their place.

This actually got me thinking. Most of the amp techs I really trust are in their 50s and 60s. I used to think that the ability to repair vintage amps would suffer when the supply of replacement parts, power supplies, tubes etc became more scarce. I confess that I totally forgot about the supply of people who actually repair them!  Asking a tech  'can you fix my old Marshall JCM 800?' will be a lot more difficult in 20 years time than it is now.

 

  • Like 1

Share this post


Link to post
Share on other sites
6 minutes ago, barkin said:

Or 2 sockets on one of the cabs.

At the moment I have the Reidmar 750 and have two ebs 112’s.  They are 8ohm each - they have a link in the back to add another cab but not sure if it will be too powerful for them 

Share this post


Link to post
Share on other sites

If your cabs are the EBS Classic 112 they run a max 250 watts a cab. I would guess you won't be running at full whack so you shouldn't have a problem. You can hear cabs start to sound bad and breakup if you are running them too hard. Start with the volume on about 9 o'clock. If that sounds OK turn it up a little more, then a little more until you either get to the volume you want or it sounds bad.

I'm sitting here running an 800 watt amp into a Barefaced One 10. The power of the amp doesn't matter, it's how far you turn up the volume that decides the cabs you use. 

Share this post


Link to post
Share on other sites
On 30/11/2019 at 11:23, chris_b said:

If you look at through the side slots on my Aguilar TH500 and AG700, you can see. . . . . . . virtually nothing! The ratio of stuff to space is about 50/50. Does anyone have any D class reliability issues these days? Not me. 

Anyone seen a pro touring PA system fail? Those FOH systems have been D class for many, many years. The PA companies who put together those systems wouldn't use anything unless it had the highest reliability imaginable. 

My valve amps were pretty good but the main ones, Marshall 100 watt and Mesa 400+, did fail on stage a couple of times over the years. I took my SS with a valve pre SVT3 to the repair shop for an MOT. The guy running the place said he'd never had one in for repair, but there were more than a dozen hire SVT's which had problems he needed to fix before they could go out again. SS amps hit a peak of reliability and it only got better with D class.

Electrical components will never have 100% reliability in anything but the failure rate these days is miniscule, but that's what backups are for. Who has used their backup amp because of a problem with their main amp? Again, I haven't. Is anyone old enough to remember the TV repair man coming to your house to fix those big wooden cased TV's? Or taking your broken radio to the repair shop? We are are at a time of the highest reliability in anything electrical.

So, to get back to the original comments. . . . . I don't see D class amps "regularly overheating". That's a generalisation that I don't believe.

I seem to remember that the early TH500s did have a problem with heat and they added a second fan that seems to have solved the problem,

  • Like 1

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...