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Haselsh1
23-12-2008, 16:56
I just thought I would pass on my experiences of buying a Yarland Pro200 SE, 300B single ended valve amplifier via the Ornec site.
In 2006 I ordered and paid for the amplifier and it duly arrived. The sound quality was stunning and was so typical of a 300B single ended design. I absolutly loved it... until 2008. I started to get flashover in the right channel 300B on switch on which would at first occur randomly but later would occur frequently.
In August 2008 I put the amplifier into the hands of a valve amplifier engineer with over fifty years experience on these units. Every single internal voltage was either over or under that specified for the valve with a general cobbled together mass of rubbish making up the circuit. Although I had bought the amplifier with a 230Volt power supply, it turned out to be a 220Volt supply. This obviously didn't help the internal voltages. The valve 274B rectifier was only supplying the pre valves as the 300B's appeared to be solid state rectified. The engineer had never before seen such a mess inside a valve amplifier. I paid four hundred and thirty pounds for this amplifier including carriage and import duty and ended up having to sell it as a chassis for sixty quid. Be warned...!!!

aquapiranha
24-12-2008, 17:19
I am very doubtful that ALL valve amps made in china are dodgy, but I suppose as with everything there will be good and bad.

Haselsh1
24-12-2008, 21:01
It's a hell of an expensive way to find out that your pride and joy is actually pride and junk.

Beechwoods
25-12-2008, 07:08
It has been noted before that some of the cheaper chinese valve amps need a thorough going over to make sure that the voltages, transformers etc are properly appropriate to the mains voltage they're going to be used with.

AnthonyTD on this board has had a lot of experience servicing / modding / buolding valve amps. He wrote the following some time back which seems applicable to what you've noticed with your amp. Marco and Anthony may have other thoughts to add once they've had their Christmas dinners :)


hi,
the main problem with the chinese amps in this case the yaqin 100b/110b is the over voltage when you try to use them on our mains supply, being when tested using a variac to find out the original design voltage ratings of the secondary windings when on load ie, amp on, drawing current etc,i found that on the 100b coming in from hong kong the primary mains voltage was 207v ac to give 6v heaters and 490v HT!!! which as you can probably work out, when this amp is used on our mains voltage, which varies easily between 238v and 253v depending on what time of day it is, and where in the country you are is way out, and because the heater voltage is around 7.3v at 240v ac, the valves will not only have a shorter life but will suffer from run away, ie, the valve will produce much more emision on 7.3 volts than it would on 6v. also, to add to this the HT voltage is around 50 to 60 volts higher, which will put even more strain on the valves, and the rest of the components, ie, power supply caps, resistors etc.
the output transformers on these amps are not bad, although in their original form, these amps use more feedback than is necesary to get a false extension of percieved frequency response.

Primalsea
25-12-2008, 09:03
I had some Yarland EL84 amps which where OK but it was probably just luck that they seemed comfortable with the higher UK mains. Don't know if they will last as long as a amp made for the UK though.

My perception of a lot of Chinese made goods is that they will make it as cheap as possible and then gradually make it cheaper still over a period of time hoping that no one notices.

People like Icon Audio may seem expensive but you know that you rely on their QC and not some poor guy in China who doesn't earn much and doesn't really care.

Beechwoods
25-12-2008, 09:17
There's good value to be found, definitely, but with some you'll need to invest a little more to get them enhanced for best - and long term - performance.

Merry Christmas all!

Haselsh1
24-02-2009, 15:52
There is an amplifier advertised on ebay at the moment called the Delphonica Valhalla that is actually labelled on the back as 240VAC. I emailed the guys to make sure and, lo and behold, it's a genuine 240VAC. It's also a 5881 power valve so nice and cheap to revalve.

synsei
18-02-2013, 06:58
There is an amplifier advertised on ebay at the moment called the Delphonica Valhalla that is actually labelled on the back as 240VAC. I emailed the guys to make sure and, lo and behold, it's a genuine 240VAC. It's also a 5881 power valve so nice and cheap to revalve.

It would seem the Valhalla I bought recently is a keeper then. I like it in every respect, it sounds utterly superb and looks good too. Might be interesting to discover how far it could be taken if I wanted to throw a little money at it.

goraman
18-02-2013, 07:40
I have a Little Dot MKIII headphone amp made in China.
It uses all top quality parts inside.
I have a lot of hours on it, they are well regarded and Sword Yang is a fantastic engineer.
I use Mullard 8100 tubes in mine.
You can get it in 120v or 220v.

http://www.littledot.net/forum/viewtopic.php?f=9&t=815

synsei
18-02-2013, 07:59
Nice one Jeff, this is my little beauty

http://i1019.photobucket.com/albums/af316/Sgtgrash/Hifi%20Stuff/56643658-3607-4e7a-ba3f-d555e1e17a5c.jpg

awkwardbydesign
18-02-2013, 09:38
If I buy anything Chinese, I always check the voltages. I use a variac set to 220v for my Ming Da amps.

synsei
18-02-2013, 09:52
The previous owner did that for me Richard and apparently all is well within spec ;)

myles
18-02-2013, 10:05
I own a Yaqin pre-amp an it has operated 'fine' up to now. However I understand that as it was built for a lower voltage it would be prudent to buy a variac. So my question is can I just buy an eBay spesh?

Barry
18-02-2013, 11:23
I own a Yaqin pre-amp an it has operated 'fine' up to now. However I understand that as it was built for a lower voltage it would be prudent to buy a variac. So my question is can I just buy an eBay spesh?

There is no need to buy a variac (which won't be cheap). Just buy a transformer that has multiple mains voltage tapping points on the primary and use it as an autotransformer. Recommend you buy one with double the power rating of your amplifier.

Dingdong
18-02-2013, 11:42
The previous owner did that for me Richard and apparently all is well within spec ;)

And you believed him? :doh:

Your heaters are at 6.3v, and the B+ 260v iirc.

synsei
18-02-2013, 13:37
6.3v eh? at least I will be able to buy some of those mighty cheap, Russion 12ax7's which litter ebay with confidence :lol:

goraman
20-02-2013, 05:24
Is that a headphone amp?

synsei
20-02-2013, 08:26
Nope, it's a single input integrated that is pretending to be a power amp ;)

tubehunter
20-02-2013, 09:25
I use a Buck transformer for the chinese amps.
Cheap and easy to make.

http://i514.photobucket.com/albums/t350/halx00/buck_zps6fb2ede5.jpg

Duncan

Barry
20-02-2013, 14:32
Good reply Duncan.

This is a good alternative to my autotransformer suggestion. Again to be on the safe side, I would recommend the transformer current rating to be double the load rating (that is, the current consumption of the amplifier).

Clive
20-02-2013, 15:20
Good reply Duncan.

This is a good alternative to my autotransformer suggestion. Again to be on the safe side, I would recommend the transformer current rating to be double the load rating (that is, the current consumption of the amplifier).
Good advice seeing as most amps this setup would be used with are Class A.

tubehunter
20-02-2013, 16:31
Yes of course


For example the YAQIN - MC-100B has a power consumption of 300watts
so requires about 1.25 amps at 240v.
A transformer with a rating over 100va rating should do trick.


Duncan

awkwardbydesign
20-02-2013, 19:47
If I buy anything Chinese, I always check the voltages. I use a variac set to 220v for my Ming Da amps.
I am intending to try a buck transformer myself at some point.

Mr Kipling
20-02-2013, 20:33
That's cheap! Where do you get them from?

Hoo. Hoooo! Ta-Raaaa!

hifinutt
26-02-2013, 03:15
having never had chinese hifi ever i am rather plaesed with this machine from china , good vfm and sounds pretty damm good, almost makes up for having to sell my arc ref 5

http://i247.photobucket.com/albums/gg160/phil125/P1010062.jpg