Mark1553552673 Posted September 24, 2003 Share Posted September 24, 2003 Hi there, has anyone built heard the various Silicon Chip 50W audio kits? how do they sound? I am considering using 6 of them for a 5.1 HTS........ thought and comments? (I am also looking at their surround, centre and sub speaker kits too.) Link to comment Share on other sites More sharing options...
Lech1553552674 Posted September 25, 2003 Share Posted September 25, 2003 Although I haven't heard these kits (are these like the SC-480 ones from Jaycar?), I've had one good experience with Silicon Chip: I once made one of their mono FM radios - lowest noise ever, and very quiet between stations..... Methinks your project is a heck of a lot more work than at first glance. If you want to make these before Christmas, I'd start thinking fast about all the little bits and pieces that the kits probably don't include: 1) Power supply, something like a whopping 450VA in total, but you could probably settle for less if you won't be cranking it. There are lots of options: separate supplies for each amp, 1 monster toroid, 2 large-ish toroids etc... At this level I wouldn't even contemplate making a switching power supply (why build a Formula-1 engine for a Volvo?). Important considerations are how much rejection of supply-noise the kits include. This also helps determine how much cross-talk there'll be between channels. 2) The usual suspects: a nice metal case, and mounting style; big heat sinks (DSE have nice 30cm ones, and check out Jaycar's monster amp design with the heatsinks on the sides); switches and RCA plugs; if you don't have something with a volume control you'll probably need a pre-amp - I find they're not that hard to conjure up.... 3) A few extra ekeltronics that I'd definitely include: a low-power transformer for powering some relays. So, instead of flicking a meaty industrial switch, you gently press a little button and a big relay switches the amp on for you. While you're at it, whip up a delay circuit that plugs in your speakers after 2 seconds or so to avoid that nasty switch-on thump. If it's all beyond you - beware of tonnes of rubbish on the internet and maybe find a book about it instead. If it sounds easy, I say go for it. Link to comment Share on other sites More sharing options...
steverb Posted September 27, 2003 Share Posted September 27, 2003 Which 50W kits?? Are you getting them from Jaycar or DSE. BEWARE OF FAKE POWER TRANSISTORS Generally they are nothing special. These Aus mag dedigns tend to quote great distortion, but they use a lot of -ve feedback to achive this taher than graet design. The 50W IC kits are qite idiot proof, have good protection circuitry & are very easy to build. Bear in mind anything you build is worthless if u want to ever sell it & cost can climb quite quckly(especially to build a good power supply) Howcever the power supply you can keep forever & just keep upgrading the amp modules I found the hardest part of DIY is getting it to look good. http://pub134.ezboard.com/ffakeidsfrm1 http://www.diyaudio.com/forums/forumdisplay.php?forumid=4 Also try posting on the newsgrous aus.hifi aus.electronics Link to comment Share on other sites More sharing options...
Mark1553552673 Posted September 28, 2003 Author Share Posted September 28, 2003 I am looking at the kits from Jaycar - the KC5346 x 2 with discrete components / TO3 case (SC 480) for the sub & centre, and the KC5150 IC amp x 4 for the 4 sides. 19" rack "case" and 2 x 300VA torroids and rectifier parts from DSE, 15,000uF caps x 4 from RS. It started off with getting a "poor mans HTS" - e.g. the Logitech Z-580?, then I asked myself, how does that sound compared to the normal entry level stuff (e.g. $1,000 to $1,700 Yamaha / Sony / Pioneer). Then a friend suggested building one from kits.... you know how it goes. So I priced up a 50w/c from Jaycar/DSE, and 6 speakers and it came to $1,700 - the same price as the higher "low" end consumer HTS. so is spending $1,700 and building it better than an off-the-shelf system at the same price? I presume the off-the-shelf systems use IC amps and have limited PSU's and low end speakers. But are the kits better or in the same league (e.g. kits = 50W RMS power/c, o-t-s = 30W or hybrid power)? the major diference seems to be the speakers (kit = more traditional 2way design, o-t-s = much smaller and maybe limited sonic range) No issue with resale (only for me) or kit building (some experience already) Link to comment Share on other sites More sharing options...
jmarshall Posted September 30, 2003 Share Posted September 30, 2003 Most HTiB systems do use IC amps in them + severly compromised power supply sections. I guess they must be using switchmode power supplies now judging by how small they are getting. I've built amps + speakers before, and I'd suggest that the amps are easier, assuming you are competent enough with a soldering iron. Just watch mounting costs from things such as fuses, switches, input and output plugs/binding posts - that's where a lot of funds can be chewed up without too much trouble - the amp modules are generally the cheap bit. A kit is a good place to start if you don't haven't done it before - the other option is to get PCBs from Rod Elliot's site (www.sound.au.com) or go completely DIY with a simple gainclone wired point to point. One thing to think about before you start - How do you intend to do volume control? This, IMO is the hardest bit of a DIY multi-channel system. As for the speakers, if you want them to sound any good, base them off a known good design (Such as mine - see my sig for links . Speaker design requires good data (from measurements) and time taken to get the crossover right. Cheap drivers with a decently designed crossover will generally sound heaps better than expensive drivers with a generic crossover. Having fun is the most important bit, ofcourse! Link to comment Share on other sites More sharing options...
steverb Posted September 30, 2003 Share Posted September 30, 2003 I'm not an 'expert' but You can get 5 channel pro logic amps very cheap now(just sold my 85W x5 for less than $200) If you just want to save money then dont bother. I built a few kits over the years. You can almost guarentee that the parts in them will be cheapest available Keep the PCB & power transistors, perhaps replace the rest. Driver transistors should be replaced with genuine Motorola(On Semi?) where applicable. Ive had generic driver transistors blow in a few of my first amps, parts then caught fire. The 480 is a very old design with problems admitted by SC. I assume u are going for the 480 "upgrade kit" The 50W IC kits can supposodly give very good sound if not pushed too hard I you want to learn a bit then get the book "High Power Audio Amp Construction Manual" from DSE, a very easy read. HT amps power IS vastly over rated.My 135W Onkyo Amp is 80RMS x 6 (from the manual) & may only be 40W all channels driven. Noway is the transformer big enougth for 80Wx6 . Add 50% to amp power output to get approx transformer VA needed (of course you can use smaller transformers but if you're going to build it, may as do it right) Speakers arnt hard to build, but the cost of drivers from Jaycar is way too high. Also the speaker specs of the generic brands are famous for being way out (ie:lies??)I bought a couple of the vifa 8" from Jaycar, worth a look? The guys post above has a link for fake transitors, local suplliers have sold them( more than once?) Link to comment Share on other sites More sharing options...
Lech1553552674 Posted October 2, 2003 Share Posted October 2, 2003 Some good stuff on this thread methinks... thought I might add a few ideas: What I'd do if making a DIY HT box is try to make the thing as modular as possible while still fitting it neatly in the box. By this I mean: make the amps removeable so that in the future improved ones can be put in their place, while keeping everything else. Everytime you think of something better, you probably won't want to run out and buy new heatsinks, buttons, cases etc. so it would pay not to make everything 100% permanent. Also, here's an idea for a volume control that will out-class many an expensive amp, by using cheap 8bit ADCs (analogue to digital converters). Eg: get an ordinary potentiometer (doesn't have to be dual-ganged), and use it as a voltage source for the ADC's analogue input. The outputs will be 1s and 0s, and use these outputs to drive small relays. Use the relays to route the audio signal through a weighted resistor ladder to attenuate the sound. Throw in more relays for more channels, and remember things like the current capability of the ADC - almost certainly you'll need mosfets to provide a high enough current to drive the relays...There's lots more to think about, but that's the general idea. Lech Link to comment Share on other sites More sharing options...
razza1553552670 Posted October 4, 2003 Share Posted October 4, 2003 This sounds all very familiar. I looked at doing exactly the same path a while ago. However when I factored in all the additional costs it was going to prove to be quite expensive. Of course there is the pleasure and (and frustration) of building things yourself. However there are cheaper ways of achieving 5.1. Check out second hand stereo amps and stack them. Second hand 5.1 Amps are also coming onto the market. Modify a good brand Pro Logic Amp. You may need additional pre - amp. Get yourself down to Axent in New Lynn they have heaps of stuff at a reasonable price also they give excellent support and encouragement. Cheers! Link to comment Share on other sites More sharing options...
PartTimer Posted October 4, 2003 Share Posted October 4, 2003 I've been using old integrated/stereo amps for my surround speakers, and reckon its great value for money. You can pick up early-mid eighties 2ch amp/recievers for around $50-$80, which pump out a solid 50w. Sure, your amps will not be tonally matched, but are you wanting to start a HT system, or spend lots and lots of money. I had three integrated amps for surround cahnnels, and have been replacing one of them every two-three months with power amps.... It's been quite entertaining playing around with mid-eighties low-fi equipment. Having said the above, I've assumed you want surround sound for movies only, not for music listening. Link to comment Share on other sites More sharing options...
cyclist Posted October 5, 2003 Share Posted October 5, 2003 Originally posted by PartTimer I've been using old integrated/stereo amps for my surround speakers, and reckon its great value for money. Hi PartTimer I've been thinking along similar lines, but haven't implemented anything yet. I assume you use a DVD player with onboard decoding and 5.1 channel analogue outs? What do you use as a master volume control (the DVD players inbuilt volume control perhaps) and do you find this works OK accross all channels? Thanks. Link to comment Share on other sites More sharing options...
steverb Posted October 8, 2003 Share Posted October 8, 2003 For a voulme control used a 5 ganged? rotory switch with a switched resistor network Or use a volume control IC Link to comment Share on other sites More sharing options...
Lech1553552674 Posted October 10, 2003 Share Posted October 10, 2003 Originally posted by steverb ...Or use a volume control IC Aaarch! I think you've broken the gold-plated-tungsten-steel rule of making DIYing at least 3/4 fun, and only 1/4 easiness! For a voulme control used a 5 ganged? rotory switch with a switched resistor network... ...and elegant!: Single pot I say, controlling the lot if you do use a resistor network (ladder or whatever)... That way you've got some potentiometers left over to do the compulsory left-right balance, front-rear fader, equalizers, subwoofer boost, digital delay..... Lech Link to comment Share on other sites More sharing options...
steverb Posted October 11, 2003 Share Posted October 11, 2003 Originally posted by Lech Aaarch! I think you've broken the gold-plated-tungsten-steel rule of making DIYing at least 3/4 fun, and only 1/4 easiness! Thats why I bought a Home theatre amp & built a separate amp just for the CD. The great trap of DIY is to much time building (& research?), not enough time enjoying the music. And of course it is much more enjoyable to listen to when you build it yourself. Now if I could just build a speaker cabinet large enough for a few rooms to fit inside... Link to comment Share on other sites More sharing options...
JamesB Posted October 11, 2003 Share Posted October 11, 2003 The DACT stepped attenuators are supposed to be pretty good. I've never tried one myself however for the price they sell for you'd expect them to perform (and be mightly dissapointed if they didn't). Here is the Aussie distributor for DACT: http://www.soundlabsgroup.com.au/ I brought "The Tube Preamp Cookbook" from Allen Wrights website (http://www.vacuumstate.com) and was toying with the idea of building one of his preamp designs. Won't happen in the short term however... Link to comment Share on other sites More sharing options...
steverb Posted October 12, 2003 Share Posted October 12, 2003 >with the idea of building one of his preamp designs Why not just a passive preamp. Much easier to just have a pot, forget about preamps & build volume pot & input selector into the power amp box. If you have a 50W amp then you dont need a preamp ( unless you have vinyl) Link to comment Share on other sites More sharing options...
JamesB Posted October 12, 2003 Share Posted October 12, 2003 Originally posted by steverb >with the idea of building one of his preamp designs Why not just a passive preamp. Much easier to just have a pot, forget about preamps & build volume pot & input selector into the power amp box. If you have a 50W amp then you dont need a preamp ( unless you have vinyl) Transformer volume controls look like an interesting area too Link to comment Share on other sites More sharing options...
steverb Posted October 12, 2003 Share Posted October 12, 2003 Originally posted by JamesB Transformer volume controls look like an interesting area too If the rooms big enough just have the speakers on remote controlled motorised wheels. Move forward=louder, move backward=quieter . This would also be a naturaly logrithmic setup (sound voulme being proportional to distance squared) Link to comment Share on other sites More sharing options...
craig f Posted October 12, 2003 Share Posted October 12, 2003 Originally posted by steverb Why not just a passive preamp. Much easier to just have a pot, forget about preamps & build volume pot & input selector into the power amp box. If you have a 50W amp then you dont need a preamp ( unless you have vinyl) From what I've read (not head personally) it's quite difficult to get a passive pre to really work. Some people swear by them for the tonal transparency but others believe that you can lose dynamics and life from the music. Also, what has the power rating of the amp got to do with requirement for a pre-amp? Cheers, Craig Link to comment Share on other sites More sharing options...
Lech1553552674 Posted October 12, 2003 Share Posted October 12, 2003 Originally posted by Craig F From what I've read (not head personally) it's quite difficult to get a passive pre to really work. Some people swear by them for the tonal transparency but others believe that you can lose dynamics and life from the music.... 'Tis what I did at first, and it was indeed very good. Easy too though: no capacitors, no nothin'. I sideways-graded to a pre-amp with a subwoofer filter as I recall mentioning somewhere, but I still need to fix all the problems with it to make it sound anywhere near as good as before. 50k dual-ganged logarithmic cheap thing from DSE did the trick, but I really do think you'll need something a bit more advanced unless you can find a 5-ganged pot somewhere. Now that I think about it, I must warn that the volume control I mentioned with the ADC is a lot harder than most people realise.... Link to comment Share on other sites More sharing options...
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