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class D amps cutting out

punchclock

punchclock

Mar 19, 2007
316
79
Kansas City
#1
who here has experienced their class D amp cut out for a second or 2 when pushing it a bit?
I've had terrible issues with 4 different brand new orange terror bass 500s.
whenever I mention it. somebody has or knows somebody who has had this issue with micro head with a class D amp.
just curious what the consensus is here on TB.
thanks.
 
#4
Yes: Once on a homemade Class-D power amp that I built from a kit, and once with a Crate Power Block. I can tell you how I did it: By turning the amps up to 11 and dropping bombs on open E until the amps quit while driving a speaker with relatively low voice coil resistance. I was deliberately trying to see if I could trigger the overload protection.

I decided that I had enough fun with the E bombs, and I don't test amps that way any more. Neither my EA Micro300 nor my GK MB200 heads have ever cut out.
 
#6
fdeck said:
Yes: Once on a homemade Class-D power amp that I built from a kit, and once with a Crate Power Block. I can tell you how I did it: By turning the amps up to 11 and dropping bombs on open E until the amps quit while driving a speaker with relatively low voice coil resistance. I was deliberately trying to see if I could trigger the overload protection.

I decided that I had enough fun with the E bombs, and I don't test amps that way any more. Neither my EA Micro300 nor my GK MB200 heads have ever cut out.
Click to expand...

E bombs? Try A0, I've shut down my SVT 7 Pro, and my Peavey IPR class D amps pounding on them, just for fun. But, under normal playing conditions it just doesn't happen.
 
#8
Hi.

I have very little experience about class D amps so I can't be specific about them, but what would You prefer, a blown amp or a speaker, or the protection kicking in?

Now whether the protection(s) is designed to be as transparent as possible or not, that is usuallly related to the price and/or quality of the product.

Take the ancient PeePee DDT for example. HORRIBLE.

Regards
Sam
 
#9
I was always happy with the "DDT" protection in my Peavey amp.

With that said, I'd prefer an amp that is designed to handle a reasonable range of operating conditions. On the bandstand, I don't want to be distracted by having to think about whether my amp will cut out. On the other hand, I have the luxury of using amps that have ample headroom for my use, because I don't play super loud music.
 
#10
im not pounding. & I'm not pushing too hard. and if that was the issue, I doubt orange would have replaced the amp 4 times without question. they know they have issues with the design (sensitivity on the protection too high).
but I've read on hear the exact same issue with the ampeg portaflex. and heard from other musicians around town , other micro amps with class D amps doing the same thing as well.
 
#12
There are several types of protection (or lack of it) possible with class-D.

One is the usual overcurrent protection, which obviously is present. That might either cut out, or simply cause a distortion. The distortion-causing type is probably preferable, but is often harder to do with a class-D than with an analog amp

One is related to simply pushing the input too hard. The "modulator" has limits, above which the "elementary version" will simply "saturate" and may put out DC. The modulator protection (assuming it is present) might limit levels, or might cause a cut-out. More complicated modulators avoid that.

Low frequencies can cause a phenomenon known as "pump-up" in which the opposite power supply (not the one being loaded) will increase in voltage due to the inductance in the "reconstruction filter" present in the amp. Some types of class-D are inherently incapable of having pump-up, others are not. Generally the problem is with extreme outputs and frequencies, outside of the normal. A modulator that puts out a DC when "saturated" also may cause it.
The problem is that the power supply voltage goes out of limits (high) and forces a temporary shut-down to prevent damage. Various schemes may be used for preventing that in the amp designs which can have it happen, ranging from cheap and less effective to expensive and 'absolute".

Class-D amps are getting better, and these problems are being solved.
 
#15
Class D power amps can't clip - if they do, they shut down. It's as simple as that.

Remember the SVT-7? The limiter is such a bad construction, that you can trigger shut-downs with a low volume level (e.g. in the shop). The salesperson believed it when I did it three times in a row with two different 7ers.

However, there are solutions, like GenzBenz (for instance) demonstrates.
So it IS a class D problem - but a solvable one.
 
#17
aledeville said:
Class D power amps can't clip - if they do, they shut down. It's as simple as that.

Remember the SVT-7? The limiter is such a bad construction, that you can trigger shut-downs with a low volume level (e.g. in the shop). The salesperson believed it when I did it three times in a row with two different 7ers.

However, there are solutions, like GenzBenz (for instance) demonstrates.
So it IS a class D problem - but a solvable one.
Click to expand...

How did you get the 7-pros to shut down? Was it something to do with the attack of the note?

I'm using class D (Orange) but it's never shut down or clipped even with moderatly heavy picking and at considerable volume, (enough to push an Ampeg 610hlf which needed a fair bit of power).
 
#18
aledeville said:
Class D power amps can't clip - if they do, they shut down. It's as simple as that.
Click to expand...

This is simply not true. The mechanism is a little different but the results are essentially identical.

How the amp handles clipping, or overloading is a big part of what seperates the men form the boys in the class D arena.

We (as thouse of us who have designed for the pro audio market) have been designing with class D for many years now, and the approaches have become more and more elegant and accommodating in how overload is handled.

An additional point is that most quality pro amps (both class D and class AB/G/H) are addressing the extremes of operation with respect to minimizing or at least controlling the stress placed on the speakers too, these big amps when operated outside of REASONABLE parameters can cause a lot of damage to speakers mechanical parts. It wasn't a big factor with smaller amps, but the migration to high power, compact cabinets changes the speaker's margin for overload at very low frequencies under high power "abuse".

Like everything in life, we do the best to develop workable compromises between performance, reliability and at the same time try to minimize damage to other components under abusive operating conditions. Some of us do this better than others however...
 
#19
ok. thanks for all the good info!
sounds like genz benz has figured it out.
guess orange still has some work to do before the TB500 is more reliable.

now, do I try to sell my 5th unit?
it hasn't had a problem (yet) - which means I'll be less guilty selling it.
sound is great, just can't gig with it. :(
 
#20
punchclock said:
im not pounding. & I'm not pushing too hard. and if that was the issue, I doubt orange would have replaced the amp 4 times without question...
Click to expand...

While Orange may be aware of the issue, my question is after the second go round when it was obvious the issue was both known to the maker AND effecting you in a negative way, why you continued to stick with Orange?

It's obviously not an across the board defect and if Orange is aware of the issue it's surely something which shows when certain combinations of settings and usage cause it to happen or they would address it if it was an actual design or manufacturing defect effecting every amp they produced.

At this point you have two practical choices, change the way you use the amp and lose the problem, or change amps and lose the problem. If that amp set in such a way as to force it to shut down, is the only amp and settings you can use to get "your" sound, then quit playing bass or become more adaptable.

Or take the third option...continue to use the amp in a condition which causes shutdown and continue to have the amp shut down on you until Orange decides it's enough of an issue overall to address, or until you get tired of beating a dead horse and decide your peace of mind is more important than making a point.

Or maybe the people at Orange just picked you to hate and keep giving you defective amps?
 

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