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peniku8

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Everything posted by peniku8

  1. peniku8

    Rob's Amp tests

    I ordered two replacement modules, will see if the current ones are the same. This amp is 7 years old after all.
  2. Yea I returned it. With the phase plug I was just refering to the general direction. I had 12 woofers in series and it was clear that this one made noise well before reaching Xmax and it was about 5db earlier compared to the other woofers.
  3. peniku8

    Rob's Amp tests

    This is so annoying. I was just way too curious to see if I could improve the amp's performance by adding those components and now I caused 150$ damage again. Well, heres more random info on the PSU: when both amp stages are disconnected, the PSU hold over 200V for an hour. I used a light bulb to quickly drain it. When it's down to 0.1V, it takes about 10 seconds to climb back to 2V. I immediately connected the 230V light bulb after I powered the amp off, when the PSU was still at around 350V from positive to negative. It was a 30W light bulb or smth, it lit up brightly for a second and the light faded completely after some 20 seconds. Very convenient way when you're working on this kind of stuff.
  4. peniku8

    Rob's Amp tests

    Seems like this amp is haunted by Hoffmann's Law. I'm not sure why but the modifications I made (wich was adding the two missing resistors and transistors) broke the amp stage. The fuses melted so I removed the components again but it's still inoperational. Welp, now the amp doesn't work at all anymore, since both output stages are broken. I'm guessing that it's a relatively minor thing, but I'm not the one to track down a broken component and I'm fairly certain that getting it fixed will be more expensive than the 150$ for the replacement board.
  5. peniku8

    Rob's Amp tests

    What confused me even more was the seemingly random choice of output transistors, as two different models were actually used in the amp. One output channel has an even distribution of both types, while the other one has 5 of one type and 9 of the other. Both are the NPN type. https://www.onsemi.com/pub/Collateral/NJW0281-D.PDF https://www.onsemi.com/pub/Collateral/NJW21193-D.PDF Looks like the 21193 is a bit better. I'll solder two from the broken pcb to the working pcb to "upgrade" the FP-13000 to Fp-14000 on the output stage. It might make a slight difference into lower impedances. 14 vs 16 transistors is still a decent upgrade.
  6. peniku8

    Rob's Amp tests

    I somehow feel like this is bad design or something isn't working as it should. The 4 transistors I replaced in the PSU, which all broke after about 2 minutes of 4KW output generate a humongous amount of heat even in idle. The heatsink seen below reaches 80°C (176°F) in idle and SOMEHOW I measure over 1KV from heatsink to ground and when I touch it with the thermo sensor I see small sparks. What is going on here??
  7. Interesting, I also had a problem with one of the 14 Dayton woofers I recently got. Very similar noise, just that I was testing at 20Hz so the "clicking" was slower. The issue doesn't seem to come from the surround on the Daytons, more like the noise comes from the phase plug (those woofers have a solid phase plug in the center instead of a dust cap).
  8. Ported subs are easy to integrate if they are the lowest playing speakers in the system. If you have ported subs and want to run something below that (like sealed or other deeper ported subs), you'll have a hard time on doing so. FIR filtering might be the only solution, at the cost of delay and ringing. But since that's not the case you won't have to worry about that.
  9. You might wanna ask this question on AVS again, but unless your cab is severely mistuned, the issues you‘re hearing are likely room issues. I have no experience with the um-18, but apparently it‘s also pretty capable in the mid-bass region. I‘m not sure if dropping those drivers in sealed cabs would yield your desired improvements. I have seen other people using (multiple) um-18s seeking for better misbass performance, which makes me wonder why not go for the 21ds115 or similar instead. I know in the states they‘re similarly priced and you‘ll lose a bit of deep bass (displacement), but you‘ll gain a lot of sensitivity. If those magnum drivers are high sensitivity drivers, I‘d give them a shot. Should work rather nicely in sealed cabs. What other subs are you using in your setup, for which you‘re hoping for better integration?
  10. What‘s the purpose of those caps? DC blocking? Wouldn‘t it possible to just short em instead then?
  11. peniku8

    Rob's Amp tests

    https://en.wikipedia.org/wiki/Capacitor#Energy_stored_in_a_capacitor You can see that the charge is proportional to C*V while the stored energy is proportional to C*V². If it wasn't "that simple", these formulas would not be that simple either
  12. peniku8

    Rob's Amp tests

    The stored energy is the capacitance times voltage squared, so at 50% voltage the cap will be 25% charged. Double the voltage and you quadruple the ‚power‘, seems familiar, doesn‘t it! Static electricity doesn‘t kill you because your capacitance is very low, so you only store a minuscule amount of energy.
  13. peniku8

    Rob's Amp tests

    @SME And luckily we have breakers in our homes to prevent that from happening inside a wall. I hope..! @kipman725 If the cap has been discharged, a simple shorting wire will do the trick even. Leaving them open is very dangerous. I'm not sure what to think about that video. I have seen it before, but he almost seems to "fanboy" over those amps and I'm not convinced if what he is saying is genuine. At times he almost sounds like a salesperson. Minor detail, but he uses the term slew rate incorrectly. Slew rate is not the time it takes for the caps to charge back up. Either way I'd of course be very interested to test the CVR amps. Looks don't tell the whole story. The Sanway also looks very well made internally, as do the Sinbosen amps, but they lack protection. Of course you won't care much about that in your HT but if your system goes silent on a gig you're in for trouble and I'd surely not want to risk that. I know Sanway have changed their PSU and it might be better now. They added a fan where my blown transitors sat. There are very few reviews or even general info about CVR.
  14. A high displacement 15" driver will do very well even at loud levels down to like 20Hz. Since most movies nowadays don't have much content below that point, a single sub like this will do the job very well. When you start with BEQ and you're aiming for a good seat-to-seat variance it starts getting ridiculous, which is why you often see guys at AVS with 4 18" drivers in huge cabs or well.. more than that. I think that my 2x21" rig is overkill for my use, but better have too much headroom than not enough..! Adding a BOSS riser to the setup (really just a sheet of plywood with two 12" drivers mounted to it, was 30 minutes of work) was the icing on the cake, since I get no low tactile response in my room (all stone and cement). If you're into "feeling the bass" you might want to look into that. And as I said, since it's basically just a sheet of plywood with two holes in it, it wouldn't steal much of your time. And since you're looking to get a miniDsp already, the total cost for that might be around 150 bucks. It's far less gimmick-y than it seems.
  15. peniku8

    Rob's Amp tests

    It will be safe to work with from a humanoid standpoint after two minutes, but that still might damage electronics when working on the amp. I'd leave it disconnected for at least 10 minutes before working on it again or using a ~400R bleed resistor to shorten the PSU, which would result in a 1A current flow at 400V, which might be useful to be connected with a switch if you plan on working on the amp a lot. I think I have a 50W 32R resistor somewhere, which would already quicken the process from 50V down to zero. But oh boy if I leave it connected and then switch the amp on... Heres a fun vid about capacitors. He has a shorting wire for storage on that thing or it would probably kill you if you touched it. This thing does over 80000A at 4000V.
  16. @Boomer1950Looks like you've done your homework, your driver falls into the low impedance category ("Low Z") and your amp seems to be 2 Ohm stable, which is why you can run it in bridge mode on the 4 Ohm load. You can let your AVR handle crossover and delay as you mentioned. I think the SI driver will be able to handle all that your amp can give, so I'd not bother with the limiter.
  17. peniku8

    Rob's Amp tests

    I also touched a heatsink in the power supply to feel how hot it gets. There was some high voltage which made my hand spasm (not high enough to make my arm hurt). I whipped out my voltage meter, which measues up to 1000V DC/AC. It showed "over" on the 1000V setting. I'm not sure what to think of this. I don't know what part of the amp stage got damaged, since I basically only shorted the PSU output. I am quite confused. I will trace the tracks on the PCB to see what the first components in line are and check those. I will also check with Sanway show much the board costs. The PSU is 185$ and this amp board is quite a lot smaller. Well for now I have an amp which does 7KW bursts and sustains 4KW. Better than a completely broken amp. Another odd thing I noticed is that one of the amp boards gets unusually hot. I will investigate this, but it might also just be normal and the broken board doesn't heat up anymore since the circuitry in the amp switched it off. I will double check without the internal input/logic connectors in place.
  18. peniku8

    Rob's Amp tests

    Update on the Sanway: I fixed the PSU but dropped a fuse into the open case just 2 minutes after I tested it without the amp modules connected. It shorted out one module and broke it. Big boom. Thought I just discharged the caps a little violently and didn't think much about it, but apparently there is something else amiss. The amp "boots up" again and one channel is operational. The "Mute" light on channel B won't go away. The fuses are good, since the Temp light will light up when those are not installed/blown. One good thing: I measured the rails and they are 185VDC+-. When I measured the amp's maximum unclipped output voltage I got 131,4V RMS, which is 185,3V peak. Looks like that measurement seems to be reliable. The amp should make 190V peak according to its spec. When unplugging the amp from the wall, rail voltage drops to 5V+- after 5 minutes. I wore rubber gloves and use non conductive tools when working on the amp, but waiting for a little longer would've prevented the "fuse incident".
  19. peniku8

    Rob's Amp tests

    More or less. You can order them via Thomann, but you‘ll pay 45$ shipping.
  20. Since I have never worked with the IPAL system before I can only speculate. Wouldn‘t it be possible to let the amp measure induced current by the driver and calculate inductance from that? Would it then be possible for the amp to actively counter that induced current? The system could surely have a ambient temperature reference FR and a high temp FR which could then be ‚faded in‘ depending on the state calculated via the dc resistance. Would be some work to set that up but what isn‘t
  21. I was comparing it to the linearization effects of the IPAL system. Afaik the system monitors driver specs to linearize thermal effects for example, and the shorting ring would just be the inductance equivalent then. I could be wrong and the system is less advanced than I think. Just that thermal effects only arise above a certain output volume and inductance is always present. The real reason for the ipal amp seems to be the driver thou. In order to meet the design goals, the driver ended up with a super low impedance, which needed the custom amp and requires to build an active cabinet.
  22. Thanks for the great explanation! So in short: the shorting ring magnetically opposes the (self-)induced field of the voice coil to reduce apparent induction by basically converting that energy to heat? If I understood that correctly, the shorting rings lower the voltage sensitivity as well? And the IPAL system works on a similar basis, just on the electric side, basically eliminating anomalies produced by induced current?
  23. I don‘t know how the shorting rings in a driver work mechanically, but as I was thinking about damping factor and that long cable runs can get problematic with low impedance systems, my head told me that the shorting rings also play a role here. Do they have an influence on the damping of the system? Is the impact big enough to neglect the amplifier-cable-system damping factor if your drivers have shorting rings?
  24. peniku8

    Rob's Amp tests

    KMT LC1300 Frequency response: Vmax(RMS): 70,4V Idle power draw: 0W (current readout was 0,0A) Efficiency into 8R: 83% Efficiency into 4R: 78% Efficiency into 2R: 69% Highest observed amperage readout: 13,5A (@232V) DC protection relais kicks in below 20Hz (only above a certain volume threshold about 10db near max output). It mutes the output for half a second. Fans only spin up when both channels are under load, amp started smelling 2 minutes into the 2R test. Single Channel 1x8Ω - 507W @1khz 1x4Ω - 842W @1khz 1x2Ω - 1304W @1khz Dual Channel 2x8Ω - 2x451W @1khz 2x4Ω - 2x723W @1khz 2x2Ω - 2x1069W @1khz
  25. A modern implementation of combining any amount of channels within an amplifier should be fairly simple. Just deploy a feedback loop system which sets gains of slave channels for their output voltage to match the master channel. I don't know much about amplifier classes, except that class H is heavy af and class D is the new super efficient stuff which makes for lightweight amps which are so efficient that they don't need big heatsinks anymore. Do you happen to know at which voltage the PS of the MA is operating at? It's probably possible to do such a retrofit yourself.
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