Chinese audio

[Rare Bird]

I've been using a Chinese 24/96 DAC come pre come headphone amp for ages now, it gets a hell of a lot of use, cost me about £130.00. The only problem i had was using my low impedence headphone which did output a slight hum, all i did was reduce a couple resistor values which cured it, not a product fault in any way..

I don't care about hifi anymore as a rule & i never get attached to any product no more so this suits me fine, anything that goes wrong at this price whats worth getting it fixed! just buy another, this is how it's suppose to work these days isnt it??..I'll probably buy the new amp they make now it's available to compliment it (again cost peanuts)..This company btw are one of the best i've ever dealt with & aftersales are brilliant.

Paying heaps of money for hifi is a mugs game imho.

[Jason P]

Jason: Do you have any more info on the amp you pictured above? It looks most impressive.

Sure, TC - it's manafactured by Image Audio...

and the thread I 'borrowed' the pic from is here...

I'm certainly very happy with mine - only problem I have is not having instructions (bought s/h) I'm not sure about bias values for the valves (currently Golden Lion KT88s)

Hope this helps!

Jason

[Techno Commander]

Thank you.

[Ali Tait]

If the amp has 220v transformers,it's easy to run it from a variac or bucking transformer to keep voltages in spec.

As for build quality,it is variable with this kit.I've had a Mr Liang 845 which was built like a tank,and used decent components,indeed the pcb's looked as well made as anything I've seen.Sounded great too,and even better after a couple of tweaks.The transformers were very good too.

The other amp was an Audioromy using 813 output valves.Build quality was iffy,but it did sound very good driving my statics.This one did die though,the mains trannie expired,though I daresay it would have been ok run at 220v.

[Effem]

If the amp has 220v transformers,it's easy to run it from a variac or bucking transformer to keep voltages in spec.

As I was reading through this thread about chinese amps designed for a 220v mains input, I thought I would mention bucking transformers and someone has beaten me to it

For those that don't what a bucking transformer is, here is a link:

http://www.dms-audio.com/bucking-transformer-diy

[Marco]

Oi, stop your bucking swearing!

Marco.

[spendorman]

This does look neat, but I am wondering if some of those resistors leads are bent too close to the resistor bodies.

This is a problem with most of the Chinese offerings, especially those on ebay. Many are made with 110/220 volt transformers which is fine for USA and Asia. Some may have 230 volt transformers which is OK for Europe but not for the UK where mains can often exceed 250 volts.

In a way, I am glad you have started this thread, as I have also been looking at getting a Chinese valve amplifier. However, I have also been doing my homework.

From what I have found so far, there are 2 main issues with Chinese kit. These are the afore mentioned mains transformer issue and secondly, there have been a number of concerns regarding assembly and quality control.

Superficially, a number of the Chinese offerings appear to offer superb value for money and if you lived elsewhere in the world, then that may be the case, but as you have alluded to, you would need to have a stepdown transformer hidden somewhere to prevent the eventual fireworks that are likely to happen when something is fed with far too many volts.

The only way to prevent this is to find a product that has a 240 volt transformed installed in it during the manufacturing process. So far, I have only found one manufacturer that does this and this is Meixing/MingDa. I know this for 2 reasns. Firstly, I have contacted the factory as I am interested in one of their amplifiers. I have received a reply stating they do indeed use dedicated 240 volt transformers in their products. Secondly, they are an OEM manufacturer for Icon Audio. Tis means they are bulding products designed in the UK for a UK market. Therefore all relevent UK and Eu safety and legislative requirements need to be met.

The factory stated they would be prepared to sell me a 240 volt specified amplifier direct, rather than going through a middle man and (possibly) getting what ever they had to hand. The factory option also comes with a warranty.

The other questionable fact with Chinese products is QC, or in some cases lack of it. I have seen some shoddily assembled PCBs on equipment. Admittedly, the message is slowly getting through and things are slowly improving, but this is more at the higher end products. The "cheap" equipment is still cheap for a reason. I do believe that within a few years there will be some absolutely stunning equipment emerging from China with relevent Eu safety approvals. Hopefully some of it will be designed/constructed to UK specifications.

Anyway, if we return to the Meixing products, the other thing which impresses me is the quality they employ in their construction. All their amps are hard wired and the quality of this construction appears to be impeccable.



I therefore feel confident that buying one of these amps will be far less of a gamble than purchasing many of the other offerings that are available. I am sure there are other products available that will also be OK for use in the UK, but I would ensure that you sufficiently research your purchase prior to investing your money.

[Jonboy]

As has been mentioned before use a Variac or simular to be safe

I have a Pair of Ming da 845 sets' and a matching pre, i have had no problem with the pre but the power amps used to distort when the volume was turned up, this was caused buy the 250 odd volts coming in to them from my supply, so i bought a variac and now run them at 220 volts the problem has gone away, something to do with the valve biasing going out of spec we think due to higher than tested voltage when built in China,

As for build quilty these are lovely underneath and very well built indeed

[anthonyTD]

hi all,
as nick and others have sugested, The main things to look for when considering a chinese made amp or any valve equipment are,,, earth bonding and correct mains voltage,,, ie: 220v equipment from experience and from extensive testing etc i have found that on some amps the primary voltage needed was as little as 207v for everything to be correct on the secondary windings.
as you can imagine when you put 250v on it the first thing to be well out is the heaters, this then leads to the ht voltage probably being over what the power supply caps are rated at etc, all in all eventualy the valves go into thermal runaway and something lets go big time!!!
not all chinese equipment is bad but quite a bit of what comes from hong kong via e++y is not directly suitable for our mains voltage.
anthony,TD...

[Thermionic]

Back in the days when hand done point-to-point wiring was the norm one of the main rules was that components should be supported at both ends, either by turret lugs or tag strips. And their wires should form a mechanical joint first, with the solder only making the electrical connection. This made for reliable circuitry and prevented components flapping about in the breeze during transit. Take a look at any old Leak or Quad amplifier to see how it should be done.

IMHO (though I was once a prototype wireman taught to do point-to-point) while the equipment in this thread looks neat, some of it does perhaps have a rather amateurish feel about it. As Spendorman suggests some of the resistors have leads bent much too near to the bodies thus causing strain on the end cap termination and possible premature failures. In another image what look like capacitors have solder joints made much too near to the bodies, probably damaging their internal dielectric. In the same picture, while very neatly wired, some of the components seem to be left with one end free to ‘flap about’.

Not wishing to offend anyone but this is the sort of wiring that I or an amateur might do for ourselves and be perfectly happy with (apart from those capacitor joints), it would not though have got past my old inspection department. And if anything went wrong later we could be in there with scope and soldering iron sorting things out. But probably not what the general user might expect to do half across the world without a handbook or service manual.

So it looks that for this type of equipment some manufactures are still very much in the learning curve and one needs to be conscious of this when ordering, especially with the mains voltage issues.

Yes I have bought Chinese equipment direct, but this a was well regarded bit of high technology where they seem to have learnt or been taught international standards of production engineering and quality. But with valve equipment the old production standards for this type of labour intensive wiring had probably been lost long before it became fashionable again.