The M20D is 115V +/- 10% or 230V +/- 10% internally selected. That is where the 90 to 260v comes from. I hope one day I can the same reaction that Dave had when blowing a powersoft amp for fun. Thank you so much for your videos Dave.
Dave got so excited when that amp blew he started bouncing up and down like a little kid! lol it’s a good thing you didn’t blow that x-4 this would’ve been like a $6000 video. I like these videos with your daughter in them. You guys make a good team. I hope you taped the next amp. I’m looking forward to seeing that video soon
@@DaveRat I don't think the newer amplifiers are meant to be run as inverters LOL. The heat sinking area regardless of fans is not as good as the backbreaking amplifiers of the past. I notice this between my Crest 9001's and it's newer counterpart the Crest 9200's. By the end of the night the 9200's sound like hoovers and have probably lost half their capacitor lives due to heat exposure.
After hearing tons of electrolytic capacitors explode, this sounds just like it. It's a good thing they don't really explode, because they have a safety vent to bleed off the pressure before it builds up enough to rupture the metal housing. Maybe you should team up with electroboom to make a video! 🤣 Seeing your daughter jump was priceless!
Dave your to cool man . If I blew up a couple of powersofts I would have been crying . I respect you man and I guess you can’t put a price on time with our Daughters. Keep doing your videos
Thanks Dave to blow up M20Ds "for fun" and science (I guess). This video series is great and I'm very pleased to see videos like that going into details and testing stuff that others don't test. I've always been convinced that one of my K3s could power another but never had the balls to try haha
Awesome. I feel like that there is something similar in the middle of my forehead that detects movement and I've told people about it to try to see if they had felt the same way. Like once a rock got thrown from a mower and I ducked out of the way, but I never saw anything. It was almost like it was just instinct. I'd love to learn more about this stuff, maybe even hear from a physiologist that could explain the mechanics involved. Great content as always.
When I used to work at Hughes Aircraft in the Radar systems division way back in 1980, we used to have Macintosh 2300 power amps in the work bench along with an oscillator. When I was testing power supplies tor the fighter jets, we would use the do exactly that and run the tone into the amp and the amp into the power supply and test for the ability of the power supply to deliver full voltage while under load. We would then alter the voltage and frequency to the power supply to make sure it met military specs.
My guess is maybe to have that range of input voltage, it has a low and higher voltage mode and works based on what it detects. But once it powered up at 77v it figured it was on 120v power, and as the voltage went way up it went outside the limits of that circuit and went boom instead of switching to the 240v mode
A friend of mine is actually the powersoft service tech and has fixed the app for me and he tells me that this model of powersoft app is the only one they make or made that requires an internal jumper to be moved and all the other models automatically slide from very low to very high voltage no problem. I've used quite a few of their amps and made the assumption that this was the same as the others and as always it's fun testing stuff out and finding out what happens.
Ok so did this with a crest 8001 (extra amp we had at show) electrics dropped a 220 at FOH and left. Put 60Hz on input and presto. We had a well regulated power supply for FOH. Yea !!!! Early 90s. Ish.
Once a colleague of mine had blown up a k20 dsp by giving it 380 volts, no biggie. The amplifier was not damaged, it only needed a varistor swap in the power supply. The m20 is probably still fine after swapping the power supply.
Looks like we found the Earth-shattering kaboom Marvin the Martian was looking for. And I guess I shouldn't have watched this video with headphones in a coffee shop with people around, I may or may not have jumped and made a noise when the amp went nuclear.
Theory- the X4 spec is a max unclipped output V of 175V. Looks like you got close to 190V on the DMM. What would the impact be of a square wave on the power input to the smaller amp? This is a great experiment, very well thought out and explained. Did you have to refer to the Crest as 'Old'? I remember when they were 'New'.... Have a great weekend!
The X4 was in bridge mono mode for channels one and two together so it had a higher voltage output. Also the X4 won't square wave a tone even if ya try due to internal protctions
7:20 That IS a great question ... and hi by the way 👋😄 ... it does seem like the fans are working harder at lower voltage and maybe lower voltage means MORE current and even though the wattage might stay the same perhaps the relevant transistors are working harder? Well on further watching I guess it BAM!! 😆
@@bsgconsulting PSU Should work harder if it is a switching supply. To get the same power out at a lower supply voltage, it has to run more current, and current is what really hits these supplies.
Agreed. It's interesting because the watts to drive the load amp should be the same, lower voltage and higher current output. Defining "work harder" is relevant. But what we do know from other applicatiins is that amplifiers get hotter and "work harder" to drive lower impedance loads. Partially due to the amp's internal output impedance being closer to the load impedance, so there are more losses to heat. So from that (and from the thermal controlled amp fans going crazy) all things point to the source amp working harder when when driving the load amp at a lower voltage while the load amp is tryin to maintain it's output wattage. Also I can see it in the X4 amp's 5 limiters using the armonia software control
Dave and Sam burn up amps so that we don't have to. This is how we know that Dave is doing real stuff on camera and not just rigged experiments. Best kind of education. I love to see wisdom passed on tot he next generation too.
👍 ha, yes, it's all real, 8 don't have the spare time or desire to do everything twice, it's all as you see and usually a single take with a few edits to shorten when babble too much
120v into an 8 ohm load? Not surprised the fans are ramping up lmao Kinda curious why the small amp popped, I don't know a ton about power supplies, though I assumed ones with such a high voltage range have gates open and close as the rail voltage drops, so all that would happen with higher voltages is the gates would have a lower duty cycle. I'm guessing it has voltage sense on startup and chooses which primary windings or something to run. Fingers crossed its something simple to fix. Been wanting to try this experiment for myself for a while now, using car audio amplifiers as an inverter. Now I know not to mess with the gain!
@@DaveRat fair enough, but there are tools for testing exactly what you're trying to do with reduced risk of blowing stuff up because an amp is doing something weird from you doing something weird. The test was basically useless because you weren't really monitoring the output of the power amp in any meaningful way. Go knows what kind of harmonics slipped in, or what kind of weird stuff the class D power filtering did to the output of the amp. If you want to make things go kaboom, that's fine, but this felt a bit weak.
Well, the amp blew because unlike all the other powersoft amps, this one needs a jumper moved. That said, using clean pure power for testing pro toyring power amps the get plugged into generators and all kinds of wonky AC is kind of the opposite of what I am I treated in. And most importantly, let's make testing fun!
this was a fantastic idea.. i had a sensory illusion when i saw the smoke.. :} since this is about generating clean AC is there a video on the 'power conditioners' topic? i'm v curious what the distortions introduced by the power grid sound like w/ mr Dave's 'signal subtraction technique'
Hmmm, interesting topic. On one hand, clean ac is such a subject of debate amongst hifi extremests, that it could interesting to dive into. On the other hand, if clean mains ac vs dirty mains ac has any impact on the audio sound, all that really tells us is that the amp has a crappy power supply.
@@DaveRat thank you, i understand. so basically the power supply is supposed to clean the AC mains and this sort of experiment would just show the absurd extremes the "hi-fi forums" can and do reach. than being said, it wouldn't hurt to have such a clear proof thru "signal subtraction" that power supplies in fact filter out junk -although i'm not sure 'extremists' suffer from a lack of data as much as some sort of trust issues.. --------------------------- on a different topic, and i don't want to abuse your time, i'd like to ask if indeed it's such a difficult process to design a "back loaded horn subwoofer" (scoop bin?) -just for entertainment purposes. --------------------------------- i'm reading some theory attempting to understand the basics by mr Martin J. King "Advanced Design of a Back Loaded Exponential Horn". i briefly checked a few forums on this topic and ppl say designing such a speaker is extremely difficult, hence my question. i assume just copying a design wouldn't produce decent results... months ago my friend and i built a high+mid array (8 x 4" transducers per side) for our "backyard parties" inspired by one of your demos about vertical line arrays and how they mask the interferences of the horizontal arrays.. the clarity and easiness it plays with is impressive compared to 'regular patio speakers' so obviously we need some low-end too. we just got 18" transducers 300W, suited for both sealed and vented enclosure but they're not pro drivers (dayton dcs450-4). we got decent results simulating bass reflex enclosures but honestly they don't look nearly as good as "pro horn subs" and as i understand it, a vented box can't compete in efficiency... ps: this is a hobby, we don't even listen to loud levels but it feels good knowing we could. it's also a great conversation subject, as ppl don't expect such authoritative sound coming from a bunch (16) of 4" speakers :)
I have not had any exposure to them. At this point "dumb amps" that lack any processing are cumbersome unless they are vintage and have some special quality to them. Software, processing, limiters, remote monitoring and all that, is so useful. That said, they do seem to be a way to get cheap power. But then again, I usually find that off brand products are not worth much if you ever need to re sell them and it is probably better to buy a premium brand used than an off brand new.
I've popped a few powersupplies like this... Well not LIKE THIS... haha but from across the pond here we have ~240V standard output, and if I've bought US gear and plugged it in without checking if it's switched to 110V on the back it goes POP just like this (there's often a tiny plastic toggle switch on the powersupply for switching modes for diferant wall volts between 110 and 240).
We used to do it to the school computors for fun by flicking the things into 110 mode whilst still turned on and connected to the 240 socket, back when I was a little sh1t. 🎉 Oh man.
Oh my poor computers. When I worked at the test lab at Hughes aircraft One of the guys made a box with a switch on it that said circuit breaker tester do not press. And there was a button with a little cover over it but you had to open the cover to press the button. And the switch was just a dead short across the wall power so anybody that came in and press the button shut down the power to the lab. The best part was that whoever did it was caught red-handed. The supervisor made us take it away after the second time it got pressed
@@DaveRat Haha! Thats too funny, next level first day at work prank. Yeah, I had more guts than sense back then, I only ever do that stuff by accident to my own gear these days heh. Me amd my pal shorted his whole house playing with electrolysis and basically shorting the powersocket out the same way, as we had just run the mains from the wall stright into the electrolyte and got the cathode and anode too close and they bridged, soso dangerous I really don't know how I made it into adulthood with some of the stuff that could of gone wrong along my escapades 😅
I wonder if the source amp went into clipping and the power supply in the little amp didn’t like square waves. To check you could monitor the output of the first with an oscilloscope.
Perhaps class D amps don't work very well on low voltage, I was trying to test one with 12v, it didn't work and was heating up quickly, its range is 12-36v. I'll try again when I get the right power supply.
@@DaveRat Well, it was toasted, I got a 24v power supply and still don’t work. What do think Dave? I’m old school (55) and in the 80s and 90s 100 watts RMS was a serious sh*t, I used to DJ with 200w for 100/120 people easily with 2 towers (double 15” woofers each) plus horns and tweeters, and that was more than enough, rarely I had to use all the power. Now they talk about 100w like with no respect 😆. For example, the pair of bookshelf JBL speakers I’m trying to feed in my current project, they say they could handle 100w, no way, 4.5” drivers, so I’m going feed them with just 60w, and that’s what I should get from the TDA7498 with 24v.
Yeah, speakers have gotten better sounding but less efficient. So we need more power than we used to. Also, those old amps were 100 w RMS continuous and the new amps tend to be 100 w peak. But also, watts are super cheap and the amp you have now would have cost 10 to 50 times more back then and been heavy and huge
I dread to think of how the power supply amp was cussing out the god of amps for being subjected to this. The class D almost certainly has a switched mode PSU. As loads go, these are a pig to drive. Restive loads: resistors, heaters and light bulbs are passive. Speakers, cables, coils and capacitors are reactive. Linear power supplies are active and fight hard. Switched mode PSUs.... Well you grab the Croc by the tail and hope. If you fancy setting this up again, put an 0.1 ohm resistor in the power line to the class D to have a look at the current on the 'scope.
Those powersoft x series amps are robust. They will drive loads below half an ohm, and power up on any compinatio of 100v to 240 volt single phase to 3 phase o
Startled, ... I jumped in reaction to both pops, ... but the second POP....sizzle really made me cringe! Anyone that's been exposed to such sounds ... knows exactly what I mean.
Well, she is also my daughter and has worked multiple warped tours, Coachella, and is the custom build tech for our soundtools products. Oh and her dad mixed chili peppers (me) for 27 years, and her mom mixes monitors for Pearl jam for 30 years but other than that, yeah, sound is fun
