Class D Amp Cutting out on stage, Not at home when testing

[BadExample]

Conditioning is a process that some people use to train their significant others.

I fear most of us here are the trainee.

 

[BurningSkies]

So I used the amp yesterday at a venue that it has had problems before. It had no problems. I'll be back at another problem venue tomorrow night. I'll definitely plug into a different outlet, and I'll bring my solid state as backup.

So the things I believe I have gleaned from this exchange are:
1. This is likely an issue with voltage drop.
2. Power conditioners don't protect against voltage drop. (please don't start arguing over this one)
3. A very expensive battery backup will protect against voltage drop.
4. Solid state amps are less susceptible to voltage drop issues.

Are those correct?

One thought, You can easily check for voltage drop in the room while you're playing. I bought a little LED voltage meter that I plug into either my strip or an extension. If you were industrious it would be easy enough to see it while you're playing. I'd want to actually keep an eye on it across the set, since conditions may change depending on how many amps are on that line, lighting, or even 'house' draws like the wing fryer behind the bar.

https://www.amazon.com/gp/product/B00MGMBCRK/

Not all power issues are voltage issues, of course. Having an outlet tester doesn't hurt and even then there's guesswork.

I will say that I found in rooms with low wall voltage, I had better luck running my power amp bridged than dual-parallel mono, which may sound counter-intuitive but isn't once you think about it...but bridging had it's own pitfalls (see below).

I am having this same problem, both at home and at gigs. My rig is an Alembic F-1X with an Alembic SF-2 in the effects loop. I am driving a Crest ProLite 3.0 which I run bridged into an 8 ohm fEarful 15/6/1. The tweeter attenuation is fully off. The ProLite puts out more than enough power to fry the drivers in this configuration so I run the attenuators on the amp at roughly half, but I’ve also tried with them wide open and the preamp gain waaaaay down.

The problem: when I lean into lower notes sometimes the Crest protection circuitry kicks in and the amp goes into protect mode and shuts down. I am certain that it’s the protection circuitry because the Crest has a warning light the indicates the circuitry is active. I’m thinking that this is an operator error problem, but who knows...

Any ideas?

Greetings. I have some corroborating stuff for you. I ran an IPR2-3KDSP for a number of years. It's basically the same amp in a different trim-grade. I've had this happen before and more than once. It was always when I hit really hard and when I was running bridged. You can try a couple things...
-Less Volume
-A good HPF
-Don't bridge

I found that third option (not bridging) was the one that worked best. I hardly had any shutdown-failures with the amp run unbridged parallel-inputs to the channels. Also, the amp is powerful enough that doing so, won't probably give you appreciably less headroom.

I never nailed down whether this was the preamp clipping the input on the poweramp or if this was the amp protecting when it tried to push too much voltage out to the speakers. I can say that not running bridged fixed it altogether.

I found that I even had these faults happen when using the DSP HPF, and even when running my HPF-3 in front of the setup.

This all said, I never have blown a speaker with my FF cabs even running in bridge-mode at loud volumes with these shutdowns. I've since moved away from these amps (I had two different iterations of the IPR). And now have a very high wattage class D amp that's a 'custom' Jule Amps build.

 

[s_wood]

One thought, You can easily check for voltage drop in the room while you're playing. I bought a little LED voltage meter that I plug into either my strip or an extension. If you were industrious it would be easy enough to see it while you're playing. I'd want to actually keep an eye on it across the set, since conditions may change depending on how many amps are on that line, lighting, or even 'house' draws like the wing fryer behind the bar.

https://www.amazon.com/gp/product/B00MGMBCRK/

Not all power issues are voltage issues, of course. Having an outlet tester doesn't hurt and even then there's guesswork.

I will say that I found in rooms with low wall voltage, I had better luck running my power amp bridged than dual-parallel mono, which may sound counter-intuitive but isn't once you think about it...but bridging had it's own pitfalls (see below).



Greetings. I have some corroborating stuff for you. I ran an IPR2-3KDSP for a number of years. It's basically the same amp in a different trim-grade. I've had this happen before and more than once. It was always when I hit really hard and when I was running bridged. You can try a couple things...
-Less Volume
-A good HPF
-Don't bridge

I found that third option (not bridging) was the one that worked best. I hardly had any shutdown-failures with the amp run unbridged parallel-inputs to the channels. Also, the amp is powerful enough that doing so, won't probably give you appreciably less headroom.

I never nailed down whether this was the preamp clipping the input on the poweramp or if this was the amp protecting when it tried to push too much voltage out to the speakers. I can say that not running bridged fixed it altogether.

I found that I even had these faults happen when using the DSP HPF, and even when running my HPF-3 in front of the setup.

This all said, I never have blown a speaker with my FF cabs even running in bridge-mode at loud volumes with these shutdowns. I've since moved away from these amps (I had two different iterations of the IPR). And now have a very high wattage class D amp that's a 'custom' Jule Amps build.

 

[BurningSkies]

I'm not seeing any reply, minus the quote?

 

[s_wood]

Oops!

Just wanted to say thanks! Interestingly, I swapped it with a pro light 2.0 that I borrowed, which is significantly less powered in bridges mono and had no problems. I am guessing that I was overpowering the cross over, based upon what you said and given Andy’s observations above. My next step is to put the three point no back in my rack and run it in parallel mode as you suggest. Interestingly, I to run and HPF-3 In front of my rack, and it hasn’t helped. That makes sense if the problem are high – frequency transients overloading the crossover, rather than low-frequency ones (which would be somewhat reduced by the LPF).

 

[agedhorse]

It's not overpowering the crossover, it's that the crossover might present an illegal leading PF load to the amp which is simply protecting itself.

The (better) class D amps are better able to protect themselves rather than blowing up (like some earlier class AB amps did).

 

[BurningSkies]

It's not overpowering the crossover, it's that the crossover might present an illegal leading PF load to the amp which is simply protecting itself.

The (better) class D amps are better able to protect themselves rather than blowing up (like some earlier class AB amps did).

I found that bridging these amps was probably not the best move. The issue went away (IIRC) once I started running in parallel mono rather than bridged. I think the Prolite has a bridge option supported the IPRs didn't (which given they're versions of the same amp, is interesting). I got confirmation from someone at Peavey that they were bridgeable with a specially constructed cable and did so. I also ended up killing or injuring several versions of this amp across a handful of years. It may have been that I was just asking too much from them or that our road schedule was just too much for what they really wanted to do.

I eventually moved to only bridging when there was a good chance of low voltage in the room. If I had clipping behavior at lower volumes than I'd normally experience, I'd switch to bridge and it usually became an un-issue.

 

[agedhorse]

Bridging could make the protection more sensitive to an illegal load (rightly so too)

 

[s_wood]

Thanks for the clarification folks! It's interesting that the problem seemed to have abated when I went from using the 3.0 (1770W bridged at 8 ohms) to the 2.0 (1160 W bridged at 8 ohms). Understanding that those specs are subject to all the usual caveats, the 3.0 is significantly more powerful than the 2.0. Does that suggest that, in the end, I was just running too much power for the single cab?

 

[BurningSkies]

Thanks for the clarification folks! It's interesting that the problem seemed to have abated when I went from using the 3.0 (1770W bridged at 8 ohms) to the 2.0 (1160 W bridged at 8 ohms). Understanding that those specs are subject to all the usual caveats, the 3.0 is significantly more powerful than the 2.0. Does that suggest that, in the end, I was just running too much power for the single cab?

The speakers never vomited their guts through the speaker grills, right?

 

[s_wood]

The speakers never vomited their guts through the speaker grills, right?

Nope... but I might have

 

[agedhorse]

Thanks for the clarification folks! It's interesting that the problem seemed to have abated when I went from using the 3.0 (1770W bridged at 8 ohms) to the 2.0 (1160 W bridged at 8 ohms). Understanding that those specs are subject to all the usual caveats, the 3.0 is significantly more powerful than the 2.0. Does that suggest that, in the end, I was just running too much power for the single cab?

That is a possibility, because as the voice coil moves out of the gap, the inductance falls which could upset the stability equation governing the amp's protection threshold for this parameter though I would expect both to have sufficient power to destroy a speaker this way if not careful.

It's also quite likely that there are more architectural differences between the two amp's circuitry than simply power, which could result in very different protection circuit thresholds.

 

[BurningSkies]

That is a possibility, because as the voice coil moves out of the gap, the inductance falls which could upset the stability equation governing the amp's protection threshold for this parameter though I would expect both to have sufficient power to destroy a speaker this way if not careful.

It's also quite likely that there are more architectural differences between the two amp's circuitry than simply power, which could result in very different protection circuit thresholds.

I've seen pictures of both on the inside (I've only owned the "3000" Peavey branded versions), and yes, even for unknowledgeable eyes they're pretty different.

The cabinets involved are using 3015LFs (mine) and 3012LFs (his), so there's not much space between XMAX and XLIM and you can hear them get ugly when you do wander into that territory and it's best to backdown quickly.

From a purely functional standpoint, the answer is that if you're having this protect failure in bridge mode it's easy to not bridge and these amps can still provide plenty of headroom as the purported wattage (rated in 'burst' albeit) is more than any single or pair of cabs can really take.

I've not had any problems with the similarly (or higher rated) class D I've moved to since, which is a Hypex based unit.

 

[s_wood]

So much good information... Andy and BurningSkies, thanks! FYI, I am running a fEarful 15/6/1 with a 3015. And I will never run the ProLite bridged again Interesting that I used to use a Stewart 2.1 with the same rig and cab, ran it bridged and never had any problems...

And did I mention that I never have any problems with my D800+ (Yes, Andy, that was for you - but it's true!).