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Spacebug

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Everything posted by Spacebug

  1. I think an amplifiers power output down low (compared to higher frequencies) has more to do with said amps high-pass/DC block filters than how "strong" the power supply is. Hopefully, some protection circuit would jump in before the ps is in trouble, no matter played frequency. Basically the amp with the lowest cutoff freq of the high-pass filter would output more power down low than another, equally powerful amp would with higher cutoff freq HP filter... Just my thoughts though, nothing tested...
  2. Ouch, wish you the best getting hdmi capture to work good. I have a terrestrial DVB-T2 USB stick that works ok for TV, pretty slow on channel changes in HD though. But I recently got fibre optics to my neighborhood and with that an IPTV box with hdmi out. If that box would ever be used for watching TV with decent audio I have to route that into the pc somehow... It has a stereo analogue out that I can use, works well for getting music from phone or vinyl to the pc but then I would be missing multichannel audio... Stuff like this are never just that easy are they? Cause where would the fun be then
  3. Not sure if it is of any help, maybe you have figured out how to do it. But a few months ago I ditched the analogue multichannel AVR I used solely for master volume duty in favor for digital master volume within the PC, going straight to power amps. I use jriver for audio processing so I'm using it's internal volume control, all well there. The quirk though is that I don't use jriver as a mediacenter, I prefer other apps, so jriver is running in the background processing sound from other apps, that is fed to jriver via wasapi loopback. With jriver in the background the real trick was how to monitor the master volume, I was not keen on adjusting volume just by ear after some 10 years of having AVR that displays master volume in the useful -xx dB scale. I tried various volume OSD programs that was supposed to flash the applied volume setting in screen, most did not work seeing as they usually monitor the default soundcard that the OS sees, but that is a dummy card that is not being used, only recieving audio and patching it forward with wasapi loopback, volume changes to that sound card does nothing... I then stumbled into the Third party plugin dev section of Jriver support forum, and saw to my surprise that there was a plugin for ImonVFD that had the features I wanted, display volume in dB scale. Jumped on that and ordered a OrigenAE VF310 VFD module, the only ImonVFD compatible VFD I could find around here. Stuck that behind one of the slots for optical drives in my HTPC case, the height of the slot was just enough to fit both rowes of characters on the VFD module so yay Put a piece of dark tinted acrylic in front of the VFD, in the slot where the ODD sled front plate would sit, looking very nice and has the same function as the VFD volume display of the previous AVR I had. I had to modify the plugin a bit to get rid of an annoying feature, and get the display to show what I wanted but now I'm pleased. As it is now it can show these different modes: "Volume -Inf" for master volume fully turned down "Volume -xx,xdB" for all intermediate master volume settings "Volume 0,0dB" for master volume fully turned up "Volume Mute" if muted Tricky thing is that the displayed volume is hardcoded in the plugin, following the default volume scale of jriver internal volume control, with 0,0dB corresponding to volume fully up, and not as a reference to THX ref volume. I'm sure that can be calibrated and the plugin coded to display calibrated THX ref volume and also "+xx dB" as well but for now this will do for me. Just a matter of making a mental note of what setting corresponds to ref volume... Oh and the volume control itself, wonderful to have the noisefloor fixed as opposed to changing with MV setting on my (fairly noisy) old AVR I used to have. Now the noisefloor is dictated by what the power amps can muster, the soundcards noisefloor is way below that of the power amps To avoid having other programs hijacking the MCE remote volume presses and possibly disrupting the operation I disabled remote control in jriver and disabled the MCE volume command from the remote and instead linked the remote to executing various batch scripts firing MCC core commands to jriver with apropriate volume up, down, mute commands. Some fiddeling with delay between each command and the remote behaved nicely, solid operation and with about the same speed of MV change as the AVR had
  4. Ricci, is your listening room closed with a door or open to the rest of the house? I ask because in my previous room I had that bump at 6-8hz and a fairly sharp roll off below 5hz when the door was open. Closed door resulted in no 6-8hz bump and less drop below 5hz...
  5. Though I'm sure there are guys stateside that can do it, and are a lot better at soldering too. I just thought posting a guide was a nice gesture as these amps are so popular in the diy crowd. Modding them would make them less crappy for powering infrasonic subs
  6. Not the same but same principles apply. Since I don't have a non dsp Inuke to physically verify with I can only go on the schematics I have, and that is of the 3000 non dsp version mind you. It appears on the schematics that, if you bypass the high-pass/low pass filters built in, only the ceramic smd cap (I assume it is) at the amplifying stage input are present in the signal path, the ones labeled "C45" and "C46" in the the guide. These caps will probably not be labeled the same on 6000 non dsp or other amps in the inuke line except for 6000dsp since they have different board layouts. So you'll have to find the corresponding caps on your amp that looks the same and are (probably) placed similarly on the board. The main differences between the 6k dsp and non dsp seems to be the signal path before the amp stage where the non dsp have an array of components belonging to the switchable high/low pass filters and the DSP version have components belonging to the DSP circuit instead. As a side note the controlling of the signal strength lights and limiting/clip circuit seems to be built into the DSP where as on the non dsp these functions are controlled by dedicated circuits. It appeared so at least as I could not get the signal lights to come on when I bypassed the DSP as a test... The other electrolytic caps shown in the guide seems to be exclusive to the DSP versions of the amp, can't be sure though seeing as I don't have a non dsp amp to physically verify on. Anyway, replacing or bridging/parallell the c45-46 caps, whatever they are called on your amp with caps of higher capacitance, say in the 100uF or above should probably yield a good reduction in rolloff, even if there are more capacitors before in the signal path. Because those caps where the ones that made most impact on my amp. Some detailed pics of the board could be useful if you want me to point them out, has to be detailed though, so components and labels are clearly visible... Hehe, well seeing as most of this forums visitors seems to be living in the US and I live in Sweden, just shipping costs alone would probably mean that any " potential customers" would back out... Hence me posting a guide instead of charging a wad of cash for some secret magic sauce upgrade
  7. An understandable assumption though. I guess there isn't too many amps employing switching output stage but does not have a switch mode power supply... But for example the LG FP series uses SMPS but usual, linear output stages, hence not susceptible to bus pumping, if i'm correct that is... EDIT: nevermind, brainfart on my behalf, misinterpreted your last post
  8. Interesting read about these amps, waay more power than I need but still interesting But, from what i've heard bus pumping is not a problem assosiated with SMPS itself but of class-d amplifiers, the amplifier stage itself that is. If class-d modules don't operate in full bridge mode bus pumping will occur. The powersupply is not the cause but rather the component that takes the beating of fluctuating rail voltages. Not sure whether SMPS is more susceptible than "linear" power supplies or not but the main problem comes from class-d amps not operating in full bridge... In full bridge mode the rail fluctuation caused by one amp "channel" will be consumed by the other, inverted amp channel causing an equal but inverted fluctuation. In non bridge mode the rail fluctuation is not canceled out by the other channel so the fluctuation reach the powersupply and it is here the problem starts. That is atleast what i've heard...
  9. Thanks! Sadly though I don't think that would be possible or at least impractical as I don't live in the US. Sweden is a good trip across the atlantic, so I guess shipping costs would make it impractical to send it over for me to mod and then return. If you want it done I would recommend finding a electronics repair store or something. Or doing it yourself, but I can understand if soldering and fiddling with a perfectly functional amplifier can seem a bit nerve racking. I thought a good long while about it myself before I began, but in the end I went ahead anyway thinking that it isn't really an expensive amp, so I could afford breaking it should that be the case. Warranty wise I didn't really care, I had done a fanswap before and then cut away a few hot-glue dabs which the service/warranty technichians probably would find. So I guess that the warranty would be nullified anyway, if they are fussy about fanswaps... Do note though that the mod will only improve the low frequency extension of the amp. It won't increase power output, only lessen the power decrease as frequency goes down. If you need more power to drive hungry drivers it won't help you. But if the power output of the amp is enough and you just want to lessen the rolloff at low frequencies it might be something for you
  10. Good that they made an effort at least.... But to be fair the firmware description says one channel redirected, which it seems to pass... Could it be they misunderstood the number of redirected channels?
  11. Inuke 6000DSP filter mod guide for less low frequency rolloff It has been a few months since i first did these filtermods for lower rolloff and the amp has run smoothly since. I did say previously that i probably could cook up a guide for the filter mods if anyone is interested, just wanted to test it out some first. Well, here it is, a guide and some random ramblings about the methods of finding these things out... CAUTION, working with amplifier internals can be very dangerous, potentially leathal, so do be careful. Do these mods at your own risk Obviously WARRANTY VOID doing these mods... Since these amps drive my sealed subs I want them to have as little rolloff as possible, so I can get the most out of my subs when it comes to infrasonic output. I did some inspection on my inukes to find out where the low frequency cutoff / DC-block filters were and if they could be modified to provide less rolloff at lower frequencies. Obviously warranty will be voided doing mods like this, something to think about although I don't care, I consider the warranty voided anyway since I have done a fan-mod before... I just want better low frequency extention from my amps... Since I did not find any schematics for this 6000DSP model, I had to use the schematics for 3000 without DSP as a general guideline. I then started working with a multimeter, probing for connections and drawing up some schematics of my own for the input signal path. I did not want to mess with anything on the "amplified" side of the board since I firstly don't really understand how it works and secondly it can be potentially leathal with its high voltage DC rails etc... So I decided to stay within the low level, non amplified part of the signal path, for safety reasons. It is also here that I suspected that any or atleast some DC-block / highpass filters would be. After I had probed my way through a good portion of the signal path and drawn up a crude schematics I looked for tell-tale signs of highpass filters, that is capacitors in series with the signal path. I found 3 areas of interest on the board, will go through each one at a time. I also did some rolloff measurements at these points to find out how much these filters affected the signals frequency response. The rolloff measurements were taken with loopback measurements in REW, feeding the Inuke amp with the subwoofer output of my HTPC soundcard that is direct coupled so it has virtually no rolloff to begin with. I should note that since the HTPC is my main source and I'm only interested in low frequency rolloff I let my usual 80Hz bass management filter be in place, so any rolloff measurements taken has first had the signal passed through this 80Hz lowpass filter. I used small measurement probe clamps with wires to attach to various points in the amps signal path and feeding that back to the soundcards Line-in input, taking ground from a screw in the Inuke PCB. First though I checked if there were any DC voltage present with a multimeter at the meaurement points, if there were any DC present I took the loopback measurements with a large capacitor in line to remove the the DC voltage and protect the soundcard. I chose a 1000uF cap, thinking it would be large enough not to introduce any noticable rolloff on its own within the frequency span of interest. This were also confirmed with a loopback measurement of soundcard sub out to line in with the 1000uF cap in line, showing virtually no rolloff at all. Now, since REW can only display measurements down to 2Hz I thought that whould be a good place to take my measurements at, it is also about the lowest frequency that I guess could be of interest for the subwoofer range. In any case, if the loopback measurement show little to no rollof at 2Hz it has probably not rolled off that much even an octave lower at 1Hz... The way I took the loopback measurements was to make rew sweeps at fixed signal level and taking note of how much the signal level had dropped at the 2Hz lower limit in REW. With the measurement methods taken care of, lets move on to the actual mod at hand. First an overview of the board in case someone don't know how an Inuke 6000DSP looks inside. I have also circled in red the 3 areas of interest. The first filter I came across where right after the input signal buffer stage, after the XLR/TRS inputs. After the buffer stage the signal goes through a set of capacitors before it is sent to the volume atennuation pots at the front of the amplifier. These capacitors are on my board named "C20" for channel A and "C32" for channel B, and are a set of electrolytic SMD capacitors of the values 47uF and 50V. The caps and volume pots, when set fully clockwise (no atennuation) are responsible for 1.2dB rolloff at 2Hz, not much but in my case I wanted as low rolloff as possible so I deemed the mod to be nessesary. Others may or may not want to do this based on your specific needs. If the volume knobs are not set fully clockwise the rollof should be a little more severe, I think, seeing as highpass filters work with a series capacitor and a shunt resistor to ground. The volume pot in this case should act as a variable resistor to ground, with less resistance the more signal atennuation you use. Less resistance to ground would mean that the highpass filter cutoff frequency moves up, in theory at least, I did not test any other pot positions than fully clockwise as that is how I always use it. I think these caps are in place to block DC voltage from getting to the volume pots as I've heard that DC present over volume pots could cause various noise when the pot is rotated. In my case I always use the pots fully clockwise (no atennuation) so in reality I don't need the pots at all, I control the input level to the amp upstream in the signal chain anyway. I decided to remove the volume pots from the equation, I did this by pulling off the PCB connector labled "X4" that has the the wires to the pots running to the front panel. This exposed the bare connection pins on the PCB, as seen in the pic below. I also know that I do not have any DC offset present at the output of my upstream signal chain components, so no DC should enter the amp input anyway, unless it is encoded in the audio that is. I don't think low levels of DC here would be harmful but I don't know, however it will anyway be caught in another set of capacitors further down the line... Also I made sure to check for any DC offset present at any side of these caps, but there were none. Had there been DC offset present at either side of the caps they had to be inplace to block the DC from reaching the other side of the cap, and the components there. With this in mind I decided to bypass the "C20" and "C32" caps alltogether and feeding the signal directly from the buffer stage to the pins on the "X4" PCB connector labled "A-VR-OUT" and "B-VR-OUT". That is the pins that the respective volume pots output to when the pot connector was in place. I did not want to do a permanent removal of the caps and volume pots, should I ever need to use the pots again, instead I made it possible to change back to using the volume pots again. I did this by soldering wire pins to the small visible part of solderpad at the capacitors input side, then made wires to bridge these pins with each channels respective input pins labled "A-VR-OUT" and "B-VR-OUT" at the "X4" PCB connector. This way I can choose to bypass the capacitor and VR pot or removing these bridge wires, plugging the VR pot connector back on and using the volume pots like usual. I would do this mod only if you want to remove the pots, if you want to use them, keep it as stock, it doesn't give that much rolloff anyway... See the picture below marking where to solder the wire pins and which pins on the connector to put the wires on. I also include a picture of which types of wire pins and wires I used, they are sourced from a local electronics shop, found them under Arduino acessories... I just pulled each pin out of the strip and bent a small 90 degree angle at the bottom to give it more support for the solder. The wires came with female connectors at both ends, I just cut and soldered them to the nessesary lengths. I used the same type of pins and wires for the rest of the mods too. Moving on to the next set of DC-blocking capacitor, these located at the signal input to the DSP module. The capacitors are electrolytic SMD ones of 47uF and 50V DC rating, 4 of them. They are on my board labled C133 and C134 for channel A, and C38, C39 for channel B. These capacitors cause a signal rolloff of about 4dB at 2Hz. They can not be bypassed since they have a DC offset of 2.5V at their output side, presumably the AD converter of the DSP has a 2.5V DC bias. The way we can lessen the rollof are either to replace these capacitors with new ones of higher capacitance, or to wire new ones in parallell with the existing ones. If you wire them in parallell the resulting capacitance can be calculated through the formula CR=C1+C2 CR= resulting capacitance C1=capacitance of existing capacitor C2=capacitance of new capacitor Whichever way you chose you should solder wirepins to each side of each capacitor. I chose to remove each capacitor to get access to the whole solderpad beneath the existing capacitors. As I do not have a hot air solder gun to desolder them with I decided to carefully wiggle each cap sideways, perpendicular to the solder pads until they came off. The idea is to weaken the material in the legs of the capacitors until they finally snap from fatigue. It is a fairly risky procedure where you do run a risk of ripping off the solderpads and traces from the board, so do be careful. If you don't want to risk that it is safer to solder wirepins to the small visible part of each solderpad instead like on the previous capacitors before the VR pots. The solderjoint can be fairly weak though seeing as it does not make contact across a large surface, so be careful when attaching the wires, so you don't break the solder joint. Perhaps cover the base of the pin in some hot glue or something to give it more support. This is how the board looks after I had soldered the pins to the board. I'm not very good at soldering fine electronics though, might be among the worst actually Afterwards you run wires from these pins to each leg of your capacitor of choice. Choose capacitors of the same or higher DC voltage rating (50V) and a capacitance you feel is right. I chose a capacitance of 470uF for all my replacement capacitors. I did loopback measurements and saw decreasing rolloff going from 100uF to 220uF and 470uF, with higher capacitance comes diminishing returns though. I also tested 1000uF caps but the gains did not amount to much, not worth the higher price and larger size for such large caps. Take note of the polarity of the original caps and wire up the caps with the same polarity as the original. The black markings on the original caps indicate the negative polarity side, that is the input side of the caps. I then duct-taped the capacitors to the top of the DSP box, so the caps stay in place and relieve the wirepins of any stress. Then there is the last DC-blocking capacitors, located after the DSP, at the input to the amplifier stage of the board. The capacitors are ceramic SMD ones labled on the board as "C45" for channel A and "C46" for channel B. These have no markings so I do not know any values on these ones, they do however look about the same size as the ones on my 3000DSP amp. I do not know the values on those either but I do have schematics for 3000 non DSP, there they are labled as 10uF. Assuming Beringer used the same ones on 3000 and 3000DSP they could possibly be 10uF on the 6000DSP too.... By my measurements these caps are responsible for about 14.5dB rolloff at 2Hz. I did measure about 35mV DC offset at the input side of these caps, no DC offset after so I thought it would be wise to keep the caps and not bypass them. I desoldered them, soldered wirepins on either solderpad and wiring up replacement capacitors instead, also 470uF 50VDC electrolytic ones were chosen here. I saw diminishing returns of 1000uF caps so 470uF it was, easy to buy the same caps for all the filtermods. If desoldering the ceramic caps seems scary one could solder wirepins directly to each end of the original ones, and wiring up the new cap in parallell with the old one. As always care has to be taken not to damage the solderpads or traces on the board... If it matters I chose the same polarity wiring as for the DSP filter mod, that is input signal on the negative polarity leg of the cap and output on the positive. A pic of the soldered wirepins for these caps, pardon my poor soldering skills again, also a pic of the complete job, with caps wired up. Not as tidy as the stock board layout but it gets the job done... Thats it for the mod, after these 3 filtermods the signal after the "C45"/"C46" caps measured as the blue trace below, 470uF caps all around. It shows little to no rolloff at all at 2Hz, do not know where the "squiggly" signal comes from, it came and went on a couple of measurements, probably measurement error or something with the line-in calibration file. The red trace are the signal after the stock DSP input coupling cap, taken through a 1000uF cap to filter out the 2.5V DC offset. It shows the signal rolloff from the stock caps at the DSP input. The green trace shows the signal after the "C45"/"C46" with stock caps at ampstage input and DSP input, but with the input coupling cap before the VR pot already bypassed. That mod I did before anything else, still that was only about 1.2dB rolloff at 2Hz so it does not have a large inpact on the figures... I also took measurements from the signal input pins of the PWM class-d chip, through a 1000uF cap to filter out DC offset and protect the sound card line input. The signal rolloff matched the blue trace at the above pic. That is not much rolloff at all at 2Hz. I cannot take measurement from the amplifier post signal amplification but I did some visual inspections of the subwoofer cone excursion when fed a signal from a signal generator. My findings were that the cone excursion did not begin to fall off until about 2Hz, and some but not large reduction in excursion at 1Hz. That strengthen my belief that these filters I have modded are the only highpass filters prescent on these amps, filters worth modifying that is. I see little point of the amp running flat out to DC, a Hertz or so from DC is where i jump off the train when it comes to neccesary extension for subwoofer amps... That is it, a guide to mod a Inuke 6000DSP to have "about flat" frequency response down to 2Hz. Might be something to consider if you are so inclined, are modding friendly and don't care about warranty, just want a "flat" amp to power some sealed subs "all the way down"... Of course I cannot guarantee that these mods are in any way safe to perform for the amp or other equipments for that matter. That being said I have run my amp modded like this for 4 months now and I haven't noticed anything bad or any odd behaviors signaling the amp might not like it. Only thing I noticed was A LOT more low end infrasonics coming from the subs when it is prescent in the audio
  12. Uh huh? Not sure if that made it clearer or more confusing. Like in only marketing and selling a product online, am I on the right track here?
  13. Can you please help a guy out here. I'm not a native english speaker and sometimes have trouble with some acronyms. I've seen this "ID" pop up here and there and can't for the life of me figure out what it means. Really bugs me not knowing what things stand for. From the context I've gathered that it means something along the lines of manufactured/mass produced but it would be nice to know what it actually stood for...
  14. That rolloff for the Inuke resembles somewhat my loopback measurements of 6000 dsp, going from memory here. Sinewaves are good though to get a feel of the rolloff, especially sweeps. Play a fairly slow sweep of 0-20Hz and look at the driver movement. That way one can get a feel for the rolloff without even measuring. If the drivers don't move much below say 3-4Hz then you have some substantial rolloff in the chain, just as an example...
  15. I feel like I stirred up the beehive, that was not my intention and I'm sorry if I came off in a hostile manner and stepped on some toes. I was just wondering why Dave thought rather less of the usual bang for buck amps diy folks usually goes for. That was atleast what I gathered from reading a bunch of his posts. But it all became clear when he explained that what he was after was a big ass monoblock to power the whole rig, or at least big ass 2 channel amp that were bridgeable to mono. Seeing as that rig would need some proper power to get the most out of it, and a criteria for a single amp to power it all, that criteria alone would weed out just about any and all of the popular bang for buck amps. Again, sorry if I stirred things up, I'm sure I could have expressed myself in a less intimidating manner. Oh and Dave, the reason I asked about the rolloff/highpass of A-14K was that I read that you use, or atleast used to use the Oppo 105. With its exeptionally low rolloff on the sub channel, it is a real shame its bass management is so effed up. I thought that if you wanted to lower the amplifiers rolloff, it could perhaps cancel out another bluray players potentionally steeper rolloff, so the end result would be more or less the same. Not accounting the Oppos fairly high end analogue circuits though, wonder if there are other players that are close?
  16. Indeed the inukes roll off pretty quickly down low, atleast if one should trust my measurements. I have the DSP version of the 6K, and those seem to have more coupling caps than the non DSP versions. At least judging by some rather low-res pics ive seen of the amp board of non DSP and a schematics of 3000 non DSP. On the non DSP ones there only appear to be one coupling cap in the signal path and that is a ceramic smd cap that sits between the amplifier part and the input part of the board. The DSP ones however also have caps between trs/xlr input buffer stage and the input attennuation pot, and coupling caps at the input to the DSP. Those at the input of the DSP is needed as there is a 2.5V DC bias at the output of that cap/input to the dsp... I'll see if I can post a snap from REW with some measurements. Note here that these measurements were done with the first coupling cap after the xlr buffer stage already bypassed together with the atennuation pot since I did not think that was needed in my case. Sadly I took no rollof measurements of the amp as a whole before doing that, however it should not matter much as the signal with that cap in place was 0.6dB down at 2Hz after the cap but before the pot, and 1.2dB down at 2Hz after the cap and after pot, so no large rolloff there... These measurements were taken with my usual signal chain consisting of a direct coupled soundcard, but AVR omitted so no rollof from signal source, all DSP settings on the inuke set to bypass. Sorry for not disabling the 80Hz bass redirection filter, it would look better without it but at the time I did the measurements I was only interested in the rolloff in the <20Hz region... Since I dont have a voltage divider set up I could not feed the amplifier output to the soundcard, instead I probed various parts of the "low level" parts of the signal path within the amp. Tests with cone excursion of my subs seem to rhyme well with these measurements, so there does not appear to be any more parts causing rolloff than those I have measured. Eeeh, how does one attach a picture to a post? Does it have to be linked from URL or can I upload directly from my pc? Have not attached any pics yet in this forum... Anyway, I can write it up. My measurement of the rolloff with stock coupling caps before DSP and before amp stage showed the signal to be -4dB @ 2Hz at the input of the amp stage coupling cap, after the DSP -19dB @ 2Hz at the output of the amp stage coupling cap, also after the DSP. Just about flat response to 2Hz in the modified state it is in now. From this one can tell that the majority of the rolloff are caused by the cap at the input of the amp stage. The non dsp versions I guess would fare some 5dB better here since they seem to be lacking those extra caps I found in my dsp amp, but I'm not sure there, seeing as I have not tested any non dsp ones... Giving a solid -3dB frequency here for the amp is sadly not possible from my measurements as I included my usual 80Hz bass redirection filter, so the input signal is ramped up around there, and leveling out at about 30Hz. This means that with the pretty agressive highpass filtering of the stock amp, that trace on the graph does not reach up to the traces for the modified filters and the trace for the signal after dsp but before amp stage input since it is rolled off earlier than the redirection filter has leveled out. Ehh, hard to describe... easy to see in pic though
  17. A capacitor would still block DC right? Just that lower cut-off frequency allows more of the AC signal in the "vicinity" of DC to pass through, that is how I've understood it... If near DC would be very harmful I don't think we would see that many DC coupled amps, or AC coupled for that matter with -3db in the 0.xx Hz regions... But as I said, don't know enough to be sure...
  18. Just speculating here but I think that could be partially to yield higher power from perhaps cheaper (?) parts. Another reason could be that it is a nifty trick to avoid buspumping that more or less plagues Class D by design, which the powersupply might not want to have. From my understanding the likelyhood for bad pumping goes up with power usage and lower frequencies, so perhaps it is no coincidence that many are permanent bridge configured? Perhaps there are other ways to avoid pumping but bridging is probably the easiest... Btw Dave,you seem somewhat obcessed about roll-off, in a good way mind you Have you investigated any eventual highpass filters in the A-14K amp? If I recall correctly I have seen some rolloff loopback graphs you posted of various recievers, and the oppo 105+amp. I don't remember if it was the 14K amp or some earlier version. Anyway, if memory serves I think it showed some rolloff from the amp, could be old graphs though so perhaps not relevant now... From my findings on the subject on my inuke amp the filter modifications are pretty straight forward once you get the lay of the land of the amp, so to speak. There could perhaps be some fairly easy roll-off reductions to be had by just knocking down the filters cutoff frequency an octave or two I do understand though if you arn't keen on investing further years (?) of testing the amplifier after filter mod, guess you have some years of testing done already. There might be some wise reasons not to modify an amplifiers bandwith though, don't know that much about amps to know what kind of problems one might get into. My amp seems fine though, as far as I can see...
  19. If one wants to power a whole system with one amp then yeah, your options for suitable amps are pretty limited, not arguing there. The same goes for using very power-hungry drivers/cabinets where it would be impossible or at least not practical distributing the power over more amps that are less capable. Yes Dave, if your posts and opinions on amps are based around whether one specific amp will power a whole raptor system or not then I get why it sounded a bit one-sided. Not many amps would be up to that task Didn't want to stir things up just that, yeah, many ways to skin the cat... Just commented on the nuke since that's an amp I have experience of. When I searched for amp to power my rather small but sufficient system when I doubled up on drivers I think I stumbled upon the amp you base your A-14K upon. Pictures looked identical at least, but the risk of buying from China and the amount of money in general made me opt out on that and just getting another inuke since it did the job well powering the system before. If I had a more power demanding system then I guess my view on things would be different though...
  20. But ofcourse it cannot power it fully However, if my understanding is correct, a Raptor system 3 consists of multiple drivers, which does not nessesary need to be driven by only one amplifier. The nuke6000 may be weak enough to not cope with even one driver, i'm not sure. My point is that if you distribute the power over a few amps, and not insist on powering the whole system with just one amp, it is not nessesary to chase multi kilowatt per channel amps and thereby ruling out all other lesser amps. Using multiple amps can be a way to make cheaper/weaker amps work just fine even in some large systems, if you just know the amps limitations and design/scale power with that in mind...
  21. No disrespect or anything here but I do get the impression from some of your posts that you more or less disregards any amplifiers that is not up to par with A-14K. That is fine and all since you're entitled to your own opinions, I just reacted to this because I have some Berry amps and know how they handle things. I think a more nuanced way to look at things, any amp really, would be to judge things by their respective capabilities. Like many class D amps Berry has "skimped" some on the power supply, not allowing a long term, full power output of the amplifier. This is done because of crestfactors, allowing high power peaks to avoid clipping is usually more important in music than long term high power output, music has seldome 0dB crestfactor But of course there is no hard rule, perhaps mostly in movies, what with directors intent and all, nothing stopping someone to put 0dBFS signals in the LFE track for instance... Anyhow, most class D amplifiers dial back the power after some short time, Berry Inuke 3000 for example drops power a few dB after 3s I think of full power. For reasons unknown, the 6000 model does not apply this protection scheme, instead just cuts out and power cycles if sustained power is too high. Tests have shown the 6000 can deliver about 1kW per channel into 8ohms for a minute (i'm guessing indefinetly). Since the powersupply is on the weak side it cannot properly power the amplifier at full power in 4ohms (due to power doubling to 4ohm). One channel at full power in 4ohms work well for 1 minute, producing about 2kW, but drive both channels to full power and it will cut out. Both channels driven to -3dB/ half power in 4ohm works well, as that gives a power draw equivalent of full power both channels driven in 8ohms. So for Inuke 6000, in 8ohms both channels driven to full power is just fine, 4ohms one channel driven full is fine, or both channels driven to half power each, but not both channels driven fully. Basically, like any amp really, just use it within its limits and it will do fine, not really any point driving an amp to clipping since it just gives distortion and no higher power... Lesser amps can work fine as long as you don't need more power per channel, powering multiple subs works just as well with multiple amps as with a single beefy amp powering them all... From my tests on inuke 6000 with modified highpass filters i also have found that frequency content does not matter, keeping it within its power limits there is no difference in the ampliers ability to drive 20Hz sinewaves or 2Hz or even 1Hz, atleast from my tests that is. Not sure if this is universally true for all amps, probably not, but still... Theoretically, class D amplifiers in half-bridge configuration would be susceptible to bus pumping at low frequencies, but since the 6000 is configured in permanent full-bridge that problem is remedied. Lastly, and I know you probably knows this, but driving a sealed sub or other alignment, with or without LT does not matter for the amplifier, if power levels are withing the amplifiers limits. My opinion is that LT should not be considered as "boost" or "more power" as the maximum power an amp can deliver is determined by the amp, not by the signal processing before the amplifier. It should instead be considered as loss of headroom, an LT of 10dB or other signal processing with signal lift just means you loose 10dB of headroom in the frequency spectrum where the lift is not applied, if one should be sure to never clip the amplifier. Sure, one can disregard that loss of headroom and drive the amplifier higher, but then it will clip if frequencies occur that gets the full lift from the signal processing, and since it is clipped the full 10dB lift will not occur at the amplifier output, instead say 5dB lift and some distortion depending on how much it is clipped/overdriven... Anyway, rant mode off! Just wanted to say that since from my side some of your posts have come across somewhat one-sided, as in no amp but the A-14K is good enough to drive subs. I'm guessing that is not what you mean, but it is how I'm perceiving some of your posts. It really comes down to ones needs if one amp is suitable or not...
  22. Borrow and test away! But videoquality, as it is digital signals should be the same as the sourcematerial. The difference is what postprocessing different players might have, and if you like those or not. For the PC i would recommend you to set the display colorsspace to same as the videos are encoded in, that is YCbCr iirc, in AMD graphics drivers that option is called "Pixel Format". I also doubt that you'll get better black levels, if "blacker blacks" is what you mean. Make sure that all programs or filters you use do not change the dynamic range or black/white levels, ie no conversion from digital 0-255 to 16-235 or the other way around. Then set the display output to full dynamic range (0-255), in AMD drivers that option is under Video/Color. This way you should not have any conversions and black/white levels should remain intact from the source video to the hdmi outputs. Then just use a calibration disc like DVE to calibrate the projector/tv to clip the signal to black at digital 16 and clip to white at digital 235. That way the display should display full black at digital 16 and full white at digital 235, the way videos are encoded iirc. Then it's the usual of basically disabling any and all other videoproccessing "features" that are usually activated by default in the drivers for some reason... I think this would be the right way to do it, that is atleast how I have it set up Please correct me if i'm wrong! This procedure should hopefully make any grievings about blacklevels etc from pc come to an end
  23. When using the Oppo with Hdmi out to a reciever I guess you would want the reciever do do the decoding. So set the Oppo to passthrough/bitstream and it will not touch the audio stream, and won't cause any issues with clipping etc. However, having a BDP which costs a shitload of money with very nice analogue audio outputs and using HDMI bitstream seems like a waste of money to me. If one doesn't care much of the build quality and such of the Oppo which I'm guessing is top notch... This is why it is so sad with this clipping issue, it has very high quality analogue outputs which are rendered almost useless as soon as bass redirection is activated, very sad indeed... Virtually any BDP should handle HDMI bitstream correctly as it is not supposed to do anything with the audio other than simply passing it in encoded form out the HDMI port down to the next device downstream for decoding there...
  24. Nick, are you sure the drivers are what is causing the sound/talk back? I have found that the limiter of the DSP sometimes makes some noise when it is operating. I firstly mistaken that for noise of voice coil former tapping the backplate but that did not make sense with the excursion I had going on with my previous 3000 DSP amp. Dial back the volume so you are just below limiter/clip lights during problem scenes and see if you hear the same sound, if not it can be the limiter causing the sound. Just a tad lower volume to keep the amp from hitting the limiter should give you virtually the same excursion as if you hit the limiter, so if it is the drivers then you should still hear the sound...
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