Elysium Posted January 26, 2009 Share Posted January 26, 2009 I agree that Samson are a good budget amp, they arent from the same raft as the others, they're quite nicely made and more like Japanese than Chinese. Those Studiospares look like Guangzhou Windforce but I can't be certain as all the chinese are at it now. Theres so much stuff coming from china and india now, I make a point of not buying it if I can. I know what you mean, a lot of equipment being made in china is less than perfect build quality. British built is the best in the world, and thats not because im british because I hate this f**kin country, but most things like mixers, speakers, amps etc.....built here are built to a very high standard. Link to comment Share on other sites More sharing options...
KevinE Posted January 27, 2009 Share Posted January 27, 2009 A particular model of budget Chinese amp that seems rather popular given what people have said is, believe me, appallingly made and I'm amused by the number of devotees they have! Resistors run so hot they char the pcb, capacitors are such poor quality that they go short circuit almost routinely, signal connectors foul mains connectors and are bent out of the way, mains cables are soldered but not wrapped & soldered, dc bus fuses are underrated for the size of fuse & current they carry (ie a 20A fuse in an 8A rated holder) and mains switches are positioned so the cooling fan draws dust through the workings. Running the amp unloaded for extended periods causes component failure that initially goes unnoticed until the component that the failed part is designed to protect suddenly fails....I could go on but it would be boring. ;-) Believe me, we can do better, people! Im not anti-chinese..because the best quality OEMs really are good, it's just that the worst OEM's really are bad! Link to comment Share on other sites More sharing options...
Sound In Gloucestershire Posted January 27, 2009 Share Posted January 27, 2009 name and shame the amp! Link to comment Share on other sites More sharing options...
KevinE Posted January 28, 2009 Share Posted January 28, 2009 name and shame the amp! Not a good idea in a public forum! I've had another cheap oriental in for repair today, not made by the OEM that makes the cheapies we've discussed so far, but a 2000W model badged by a well-known long-established british brand who should know better. (ok..beat 'em or join 'em..I know). The customer report was that 'the front panel was smoking'. Upon test the amp initially worked but I noticed the bench ammeter bouncing a bit in idle, there was a faint clicking noise from the amp somewhere. On this amp there are analogue meters on the front panel and they're soldered to a small pcb that contains (fair enough) the gain pots, clip and power LEDs. Unfortunately, it also contains the mains inrush circuit, ie Mains Relay and 220R inrush resistor. The problem was that one of the mains toroidal faston connectors was arcing causing the inrush relay to bounce in and out as the connector arced. This in turn had caused the inrush resistor to get stinking hot..it had melted itself into the right hand VU meter (glued in) which had detached its movement and this was now festering on top of the inrush resistor and smoking. To me, (not exactly a designer) it seems obvious that an inrush resistor (or anything else that under fault conditions can overheat at mains voltage) should not be placed anywhere near (never mind touch) a plastic VU meter connected in the signal chain. Yet this amplifier had the feature by design! In the late 60's people like BEAB strove to minimise risk from knock-on effects of component failure in domestic equipment, I would hope that most amplifier designers or engineers (we have a few in the BR) would not make the mistake that the chinese had obviously done with this one. Yet this nameless amp is very widely sold in the UK and is not one of the cheapest!! Luckily, the owner had taken the amp out of service as soon as he'd seen smoke and averted a dangerous situation. Link to comment Share on other sites More sharing options...
drsound Posted January 29, 2009 Share Posted January 29, 2009 Believe me, we can do better, people! Im not anti-chinese..because the best quality OEMs really are good, it's just that the worst OEM's really are bad!This is a very good reason why they're so cheap. Would I use them on a tour or Top 40 band? God no, it would be big brand amps costing ten times the price every time. Would I recommend the use of them for small live shows, schools etc where the failure of an amp wouldn't be a disaster? Absolutely. You get what you pay for and you buy, in most cases anyway, reliability. Don't be fooled by a badge though. A £300 QSC, Crown or whatever isn't going to be anything like a £2000 amp from the same brand. It probably won't even be designed or built by them, just bought form an OEM catalogue and badged up to look the part. On the subject of QSC RMX, on which we have a handful, I was advised by a fairly clued up source that the non-HD versions are in fact rebadged versions of one of our favourite German manufacturer's budget offerings. Link to comment Share on other sites More sharing options...
Rob_Beech Posted January 29, 2009 Share Posted January 29, 2009 On the subject of QSC RMX, on which we have a handful, I was advised by a fairly clued up source that the non-HD versions are in fact rebadged versions of one of our favourite German manufacturer's budget offerings. It's fairly old news that the same design, which is (or certainly was at the time) free to use is implemented in several amplifiers. Of course, we see cheaper components going into the cheaper amps offered by budget manufacturers, but overall they al seem to perform well at their price tag. Rob Link to comment Share on other sites More sharing options...
KevinE Posted January 29, 2009 Share Posted January 29, 2009 I was advised by a fairly clued up source that the non-HD versions are in fact rebadged versions of one of our favourite German manufacturer's budget offerings. Not quite, its the other way round I'd say. The aforementioned cheapies are copied from a standard QSC class-H design. The QSC RMX2450 is vastly superior in component quality, build quality, performance, safety and reliability compared to the budget brand's equivalent. Not only are the internals better but the case pressing and finish is vastly superior..in fact all the panels on the QSC case actually go together without having to pry them or re-drill any holes or file any edges. The QSC RMX are mainly built with SMT with minimal thru-hole components, (still built in China though...see..they can make good stuff..) whereas the copies are all thru-hole apart from the more reliable ones as made by Be*****er. The electronic design of the genuine RMX range is actually rather good which is no doubt why the chinese chose to flatter QSC by allowing themselves to be inspired by QSC schematics when they designed their own. Visually, the layout and cooling appears to me 'inspired' by Crest thought the schematic is definitely QSC. There are minor differences, for example the non-QSC ones seem to use a few less of the same transistor for the same stated power output, they seem to use a watt-or-two less rated resistors in the power supplies, they have DC protect relays rather than QSC's crowbars, etc etc...all to shave off a few quid here and there! BTW here is a standard view of part of a working chinese QSC copy. It's not faulty..they're mostly like this and you'll only see this when the amp fails for another (or this getting worse) reason. http://sublimeentertainment.co.uk/MiscImages/Image049.jpg For the technically-minded, these resistors are a couple of about 10 on each channel that run rather warm. The ones in question in the pic form part of an RC network across the speaker output, the adjacent brown capacitor in this case being the other part. These caps often go S/C and blow the resistors open, often the amp keeps working or sometimes the bus fuses blow..replacing just the fuse allows the amp to carry on working till the rail switch snubbers blow or something similar. Sometimes the rail switches themselves go S/C and then the ouput stage cooks and eventually fails by which time the op-amp power 15V split power rail zeners have cooked and fried all the chips. To be fair they do sound good when they're working and before the bias pots drift out of adjustment. Link to comment Share on other sites More sharing options...
dbuckley Posted January 29, 2009 Share Posted January 29, 2009 Another opportunity to link the piccie! http://www.davidbuckley.name/pix/qscvsep.jpg Link to comment Share on other sites More sharing options...
smalljoshua Posted January 29, 2009 Share Posted January 29, 2009 QSC on the left, Behringer on the Right? Josh Link to comment Share on other sites More sharing options...
KevinE Posted January 29, 2009 Share Posted January 29, 2009 Well, by contrast, here is the QSC RMX 'inspired' schematic but rearranged into the cheap amplifers that have been lauded in earlier posts in this topic and illustrated by the burned resistors in my previous post. Different layout (L&R on seperate modules) but identical to...sorry..inspired by..the QSC. (In this case the RMX2450). Who except for an engineer studying the schematic would realize?? The side-by-side previous post..yes..but this? Well there you go. http://obrazki.elektroda.net/27_1217524725.jpg On this unit the right hand module signals input header has fouled the rear-mount mains fuseholder and the connector is thus bent (ripped partially out???) at 45deg from the pcb. ANd, yes this is the model where the wires to the fuseholder are just touch-soldered to the tags..I've had one come away and spark only a couple of millimetres from the RHS signal header. For the technically minded, the components on the heatsink are (RHS back to front) 7824 reg, bias diodes, 2 parallel predrivers, 4 output transistors, fet rail switch, double diode rail isolator, fan/overtemp stat. The same is roughly present on the underside. In some versions the single rail switch fet is replaced by 2 smaller fets in parallel. Bigger amps simply add more of all output devices! L & R modules are the same except one has a slot filed out of the heatsink and one is mounted upside down. In each case the burned resistors appear all down their lengths. Ive seen at least 5 UK-market brands that use this chassis and am finding more all the time. Link to comment Share on other sites More sharing options...
dbuckley Posted January 29, 2009 Share Posted January 29, 2009 double diode rail isolator Eh? Wozzat?? Link to comment Share on other sites More sharing options...
KevinE Posted January 29, 2009 Share Posted January 29, 2009 Eh? Wozzat?? They allow the switching fets to switch the bus to the high level rail without backfeeding into the low level rail. Link to comment Share on other sites More sharing options...
subsOn Posted January 30, 2009 Share Posted January 30, 2009 As I've spent long enough ranting off topic on other threads, how about a post that answers the OP's question... A friend of mine has been using these Yamaha amps for a few years and has had few major hassles with them. Sonically they are acceptable for the price, although I wouldn't use them for subs. In fact, I'd be looking for something heavy and expensive with a transformer in it for subs, but that's another topic entirely. I would also recommend that you go for an amplifier whose rated watts rms output is significantly higher than the stated watts rms output, you'll thank me in the long run... alan singfield. Link to comment Share on other sites More sharing options...
KevinE Posted January 30, 2009 Share Posted January 30, 2009 how about a post that answers the OP's question The OP asked if anyone had had any major issues with Thomann T-Amp TA series amps. I was trying to answer his question without being libellous! Link to comment Share on other sites More sharing options...
djmatthill Posted January 30, 2009 Share Posted January 30, 2009 AudioHead amps are also very cheap and reliable little Amps too... Someone told me Audiohead , Cmark & Thomann Amps were the same beast ,, Is this true ?I must admit they do look cosmetically similar. Matt Link to comment Share on other sites More sharing options...
Recommended Posts
Archived
This topic is now archived and is closed to further replies.