Guardian-86 clarifying questions

DEN

Member

Guardian-86 clarifying questions​

What is the speaker shutdown speed?
How quickly does the protection work? I didn't find this option in the description.
Create an accident and show how the protection works on real speakers.
I'd like to see this on video.
 
The shutdown speed depends on how much DC voltage is applied at the input of the Guardian-86. I don't have the numbers memorized, but it's in the µs to low-ms range for common rail voltages. I'm sure it wouldn't sound awesome, but the speakers would experience no worse trauma than a good bass thump played with the peaks near clipping. In fact, the bass thump could be worse.

I'll run a simulation to figure out the shutdown speed. That seems like good data to have.

I have a few other priorities right now, so I won't promise a video anytime soon. My top priority is to find myself another car as I was T-boned yesterday by a guy running a deep red light (as in: it had been green in my direction for several seconds before I even approached the intersection). He was going 50-70 km/h (says police). So I got to spend my afternoon in the ER getting a CT scan of my head (precaution!). The good news is that they found my brain (yay!) and also that I don't have any bleeding within it. But I have a bit of a concussion so I'll lay low for a little bit. I'm also pretty sore, but I'm pretty sure that's muscular. The car is a write-off.
Pay attention when you drive. Those cat videos can wait. Oh... And also stick around after the accident. The guy took off. Classy move. Witnesses gave a good description of the vehicle and a partial license plate. So there's hope that the police will catch up with him. Felony hit & run is taken seriously.

Oh, well. This too shall pass.

Tom
 
I offer my condolences.
I wish a speedy recovery.
Installing a DVR allows you to resolve controversial issues in car accidents.
 
Thanks for the well wishes. I'm sure I'll be fine but it'll take some time. I definitely have a concussion and I have a hard time reaching down with my left arm. And Lord help me if I sneeze.

I get the point of the dash cams. I just don't like them. I hate the idea of living my life in perpetual fear of an accident. Statistically I shouldn't have another accident in my lifetime (knock on wood). The number of traffic accidents per vehicle mile traveled is extremely low. I doubt there'll be much controversy in my case. There were witnesses.

A real inductive load should be used. Real speakers. Then the data will be objective.

That's actually completely unnecessary. I can simulate the shutdown time vs applied DC voltage in much greater detail than I'd be able to measure in the lab. That'll answer your question. The video would just be for show. With a MOSFET switch I'm not concerned about inductive flyback causing the switches to arc over. I would be concerned if I was using a relay.

Tom
 
Guardian-86 did not pass the test in practice?
Wasn't there a high voltage at the input of this protection with a real load in the form of speakers?
Did I understand you correctly?
 
What are you on about? Of course it passed the test in practice. I applied different levels of DC to the input and monitored the output to make sure that it turned off. I found the shutdown time reasonable (= on the same time scale as a bass thump). But I don't recall the exact test conditions and the exact shutdown time to 17 significant digits ... in part because no instrument I own can measure time (or voltage) that precisely.

I know that the shutdown time depends on the applied voltage (lower voltage -> higher shutdown time) because I understand how semiconductor devices work. I also know from decades of experience that semiconductor models are pretty darn accurate for simulating timing circuits that depend on RC time constants and transistor currents. So I don't need to spend days in the lab generating the data you requested. I can do that inside of an hour in a simulator once I'm able to focus.
I also understand how MOSFET switches work and know that they can reliably turn off an inductive load. I use them in that application in many places. Successfully. As do countless others.

At common rail voltages exceeding the ±12 V minimum for the Guardian-86 the Guardian-86 will turn the output off in a few ms at the most if the amp shorts the output to either supply rail.

I have told you already that I will deliver the data for shutdown time. I have also told you that I am recovering from a concussion I sustained in a car accident. I am trying to limit my screen time a bit here. Please accept this. Please accept that there are 24 hours in my day and that this task is not my top priority. I really don't understand your angle here. What is it that you are trying to imply?

Do you seriously expect me to buy a $200k pair of Wilson speakers and a 100 V power supply so I can test the Guardian-86 under "real world" (or unreal world) conditions? At my time and expense. For your entertainment. Really?!

Tom
 
Last edited:
You're exaggerating a little. I've looked through the settings and haven't found any data on how fast the speakers turn off. You have many detailed videos about assembling and testing amplifiers. But there is no video about protecting the speakers. There is no verification of the actual operation of the protection in shutdown mode. That's why I asked questions.
The price of Guardian-86 is quite high. That's why I want to know more about what I'm paying for.
 
Your question about the shutdown time is entirely fair. Thank you for asking. And I promise you that I will deliver an answer. I made this promise a few days ago too on both forums where you asked. Please be patient and give me a bit of time here. I have told you the reason I need the time.

I think a video would be really cool to have too, but that has much, much lower priority. My top priority right now is to recover from my concussion.

I did verify the performance of the Guardian-86 before I made it available. I tested its sonic transparency and its ability to protect speakers in the lab.

Tom
 
Last edited:
Very interesting.
But it is not clear where and how this was measured and obtained.
Natural testing and experimentation are of interest.
 
Very interesting.
But it is not clear where and how this was measured and obtained.
Natural testing and experimentation are of interest.

I believe that information is implied from Tom's earlier post:
...
I also know from decades of experience that semiconductor models are pretty darn accurate for simulating timing circuits that depend on RC time constants and transistor currents. So I don't need to spend days in the lab generating the data you requested. I can do that inside of an hour in a simulator once I'm able to focus.
...
 
Thanks. I hope so too. I'm doing better but still have some whiplash and also seem to tire much faster than I did before the accident. It's a bit annoying and it reduces my productivity.

Tom
 
Get well soon Tom.

Has anyone used Guardian-86 on an OTL amplifier, seems like a good application? But I guess the signal would flow through the MosFET, so not quite so OTL / direct anymore?
 
Thank you.

OTL = Output Transformer-Less? If so, I don't see why routing the signal through a MOSFET would change anything about that. You can't have speaker protection without some sort of switch.

The Guardian-86 can be used with an OTL amp. Whether it'll eliminate pops on power-up is another matter. The turn-on delay in the Guardian-86 is about five seconds, so you'd have to turn the heaters on first. Then the B+. Have the power supply to the Guardian-86 turn on at the same time as the B+.

Tom
 
Back
Top