Definitely - there are some cheap Chinese amps with quite good opts (e.g. dynavox vr-70e), certainly considering the low prices. I bet there are lots of offerings on seperate Chinese opts in places like ebay. The shipping cost to the UK would defeat the purpose though.
www.die-wuestens.de is an excellent address for high quality/low price opts in Europe, shipping to Belgium is remarkably low so the UK might be cheap too.
Simon
www.die-wuestens.de is an excellent address for high quality/low price opts in Europe, shipping to Belgium is remarkably low so the UK might be cheap too.
Simon
Klimon said:
Careful though, I just won an auction for a pair of beautifully built Asian no-name toroidal 5K SE OPTs. They were the last the seller had and won't come up again. He used them in at least two of his home amps, including a nice looking 300b. Nor did he ever hear complaints about those sold in the past. Since many don't measure what they build however no one seems the have noticed the trannies were improperly designed and can't seem to withstand any DC current. Bass was 2 dB down at 100 Hz with standing biases as low as 20 ma. Parafeed they work fine.
The brand name printed on the side is a company specializing in power transformers and custom work. My guess is someone fancied themselves an OPT designer and commissioned a run, selling them off when they realized the error (or not!) This seemed like an ideal auction win. Many pairs were sold in the past, typically for 2.5x what I paid, the seller's rating is top notch and yet the product is hooped.
Before going this route I recommend searching for prior experience with the product on this and other DIY forums.
rdf said:
Cutting between the lines.....the above this is buyers horror story to catchout the unexperienced.
Over 40 years I've fixed perhaps too many first time experimentor 10-20W kits which came with crappy output transformers.....still the most critical single item.
The UK has by far the most time-served and experienced audio transformer designers around still in their winding houses. History says it. The drawback is they want too much for their product.......BUT it is good quality.
richj
You get what you pay for. A decent output transformer requires quite a bit of interleaving of primary and secondary sections. In other words, you wind a bit of primary, stop, bring out the wires, and wrap a bit of polyester tape over it. Then, using a different gauge of wire, you wind a bit of secondary, stop, bring out the wires, and wind a bit of polyester tape over it. And you keep on going like that, stopping and starting. That's a lot of work for a push-pull output transformer, with four secondary sections and three primaries in each half. Then, of course, you connect all your primary sections together to make the centre-tapped winding that the constructor expected and connect them to something more robust for the constructor (tagstrip or multicore flying leads). Having wound the bobbin, you need to stack the core, alternately for push-pull, one on top of the other for single-ended. If it's single ended, some tape needs to be added to define the gap. Now the shrouds can go on.
As you can see, making an audio transformer is labour-intensive, so paying cheap labour in China might make sense, but they would need to know how to wind the transformer and to exercise proper quality control (and use proper materials). The production runs are short so you can't save production costs by bulk buying materials.
Oh, and what about the cost of designing the transformer in the first place? Power transformer manufacturers generally haven't a clue about audio. There are so many variables in designing an output transformer that making good output transformers is an art, and it's partly gained by experience, so when you buy a good output transformer, you're benefiting from years of that company making and testing audio transformers.
The bottom line is that once the knowledge of how to make good audio transformers is lost, it is highly unlikely to be regained. So support your national audio transformer company and don't sell them down the river...
As you can see, making an audio transformer is labour-intensive, so paying cheap labour in China might make sense, but they would need to know how to wind the transformer and to exercise proper quality control (and use proper materials). The production runs are short so you can't save production costs by bulk buying materials.
Oh, and what about the cost of designing the transformer in the first place? Power transformer manufacturers generally haven't a clue about audio. There are so many variables in designing an output transformer that making good output transformers is an art, and it's partly gained by experience, so when you buy a good output transformer, you're benefiting from years of that company making and testing audio transformers.
The bottom line is that once the knowledge of how to make good audio transformers is lost, it is highly unlikely to be regained. So support your national audio transformer company and don't sell them down the river...
Confirmed on all counts. Not only did the designer not understand the special requirements of DC current in a toroid, the finer details of winding seemed to have slipped through the cracks as well. Parafeed it was flat to 20 kHz but began rolling off soon afterwards, nothing special in general and fairly poor for this type of transformer. To be fair to the manufacturer, I'm sure they did an excellent job of building exactly what they were asked.
Still, at under $90 pair they'll probably make a real nice 6CW5 or 6BQ5 SE parafeed.
Still, at under $90 pair they'll probably make a real nice 6CW5 or 6BQ5 SE parafeed.
This is interesting because I tookup a local designer (here in Switzerland) who said he could design a good quality p-p tube o/p tranny for me. (Never assume the person who one is dealing with has any clue) unless it's the designer himself and if you know something about making a spec; youv'e got him on hanging on the ropes). That's where the problem lies.
The company website claimed any transformer or choke could be designed.
SO I took them on. I provided a spec and within a couple of weeks heard no reply. So I was sure they were sweating over it. Then I got reply, "sorry I'm after isn't on the program",-> implying can't do it.
Same time I also submitted spec to a UK house down south and got same day reply and spec haggling started. The trade off is obvious, a 18 sect design takes more time than a 3 section and one has to justify specified leakage inductance v.s b/w and other winding issues.
Some designers still work all out with slide rules and maths. Others use a prepared computer program so the end product is prettywell anticipated and production reliable but can lead to cutting corners, i.e less iron, higher thd at LF cutoff freq and anticipated throughput power.
If the design justifies...a good designer who knows his salt will instruct self healing paper not polyester for interlayer insulation (lower dielectric capacitance)
Magnetics has always been portrayed as a black art when it needn't be. It's a pity that so many of today's science graduates lack the imagination of magnetics knowledge when SMPS is so closeby. Creating a specification is the single most challenging aspect for any engineer.
richj
The company website claimed any transformer or choke could be designed.
SO I took them on. I provided a spec and within a couple of weeks heard no reply. So I was sure they were sweating over it. Then I got reply, "sorry I'm after isn't on the program",-> implying can't do it.
Same time I also submitted spec to a UK house down south and got same day reply and spec haggling started. The trade off is obvious, a 18 sect design takes more time than a 3 section and one has to justify specified leakage inductance v.s b/w and other winding issues.
Some designers still work all out with slide rules and maths. Others use a prepared computer program so the end product is prettywell anticipated and production reliable but can lead to cutting corners, i.e less iron, higher thd at LF cutoff freq and anticipated throughput power.
If the design justifies...a good designer who knows his salt will instruct self healing paper not polyester for interlayer insulation (lower dielectric capacitance)
Magnetics has always been portrayed as a black art when it needn't be. It's a pity that so many of today's science graduates lack the imagination of magnetics knowledge when SMPS is so closeby. Creating a specification is the single most challenging aspect for any engineer.
richj
Shipping, even surface, quickly erodes any perceived price advantage, for the UK as well as to the US. Over the last few years I purchased a Daburu 5K 10W SE, Eastern Audio 3K/5K 20W SE and 10K/50W SE. All the transactions were smooth, but cost including shipping to US puts them all in the $70-$110 each range. Fit and finish in all cases has been very good. In general, to my ear they are better then all variety of Hammonds but not as good as James. In North America the small James 6115HS are cheaper (from Euphoria Audio) and sound much better to me. While I haven’t heard them Magnaquest’s SE or Parallel Feed Robin Hoods sell for $100 each. Freight from China is what kills any suggestion of a good deal in my experience.
Matt
Matt
What about EdcorUSA?
I've got a pair of Hammond 1627SE with my 6550 and brought home Edcore's CXSE25-8-2.5K (that is "the same" judging by what the papers say). This blue monstor goes with 2A3 as soon as I've got the floobydust from HongKong.
Also got a apir of (smallish) Edcore XPP10-8-8K to go with 6AQ5.
I live in Sweden so Lundahls would normally be a 1st choice but I am rebellious and avoids stuff with too high rating, and besides they look awful and need covers.
Else in Europe cheap Xformers can be found in Germany:
Röhrentechnik
in England
Mike's
and there's an Italian place too:
Elettronica Novarria
I've got a pair of Hammond 1627SE with my 6550 and brought home Edcore's CXSE25-8-2.5K (that is "the same" judging by what the papers say). This blue monstor goes with 2A3 as soon as I've got the floobydust from HongKong.
Also got a apir of (smallish) Edcore XPP10-8-8K to go with 6AQ5.
I live in Sweden so Lundahls would normally be a 1st choice but I am rebellious and avoids stuff with too high rating, and besides they look awful and need covers.
Else in Europe cheap Xformers can be found in Germany:
Röhrentechnik
in England
Mike's
and there's an Italian place too:
Elettronica Novarria
As suggested, bying a complete China-amp may be a practial way of getting decent (but not excellent) transformers.
A just did some measurements of a small Yarland EL84 amp, and was a bit surprised that the frequency response was flat from around 10Hz to 45Khz. Measured without global feedback connected, at 1W, with 8 ohm load.
Primary DC resistance was 230 + 255 Ohm, probably an indication that interleaving has not been considered ?
SveinB.
A just did some measurements of a small Yarland EL84 amp, and was a bit surprised that the frequency response was flat from around 10Hz to 45Khz. Measured without global feedback connected, at 1W, with 8 ohm load.
Primary DC resistance was 230 + 255 Ohm, probably an indication that interleaving has not been considered ?
SveinB.
hi mwiebe,
very thaks U share your experience. since early daburu OPT was ask another china audio company OEM for Daburu. But on the end of 2006. Daburu set up their private production line in china. Yes, china, otherwise the price of Good OPT cannot maintain in very good P/C ratio & cannot use the cheap labour cost to employ more exerience technian to hand winding. Nano amorphous OPT, superalloy OPT & coming 4N & 5N monocrystalline silver wire OPT.
photos I will Upload later. U can directly order from me. Since I can directly offer factory price for U. U can choose which spec U like. Nickel-Borob base Nano core & superalloy core will offer 1 months for testing. If use one month still cannot satify. Daburu will 100% money back for U. only deduct the postage.
photos show the cross-section area of the Nickel Base Nano core.
thx
thomas
very thaks U share your experience. since early daburu OPT was ask another china audio company OEM for Daburu. But on the end of 2006. Daburu set up their private production line in china. Yes, china, otherwise the price of Good OPT cannot maintain in very good P/C ratio & cannot use the cheap labour cost to employ more exerience technian to hand winding. Nano amorphous OPT, superalloy OPT & coming 4N & 5N monocrystalline silver wire OPT.
photos I will Upload later. U can directly order from me. Since I can directly offer factory price for U. U can choose which spec U like. Nickel-Borob base Nano core & superalloy core will offer 1 months for testing. If use one month still cannot satify. Daburu will 100% money back for U. only deduct the postage.
photos show the cross-section area of the Nickel Base Nano core.
thx
thomas
An externally hosted image should be here but it was not working when we last tested it.
hi all,
4N & 5N silver wires for Daburu Audio transformers.
5N was special tailor made for ( monocrystalline with 4 layers polyurthane coating.
thx
thomas
4N & 5N silver wires for Daburu Audio transformers.
5N was special tailor made for ( monocrystalline with 4 layers polyurthane coating.
thx
thomas
An externally hosted image should be here but it was not working when we last tested it.
Whilst moanin' about Chinese transformers lets be clear
Thomas is an exception!!! (At least so I've heard) the audio industry in HK is NOT the same as in China (you can hardly believe). I speak here as a humble consumer! you want quality go to HK where the guys will be at least as interested as you. You want a good price go across the 'border' to Shenzhen... and keep your shirt on...
Hope I'm not selling you short there Thomas. (or over doing it)
BTW that little Yarland amp is a cracker - I've said it before. Although I cant really justify another,l I'm thinkin about it they are THAT much fun.
For OPT's the Chinese amps seem to be OK - buy a KT88 amp,if you wanna drive EL34's. But you still might be lookin at $200 for the whole thing. OK - I know you guys in the US might get better domestic deals than us limeys, but $200 us for a decent st of OPT's is unheard of (anyone knows better I need to know!!!!!)
my GENERAL experience is that the Chinese OPT's are not bad but the power trafos are always HOT. Ok I tend to look at KT88 etc. so the current hungry end of things. Still odd that its the boring end of things that get warm?
Actually I'm thinking about this I might get my deerstalker on and do a bit of investgatin' next weekend. Thomas you must have heard hundreds of these any you' would like to recommend?
Andy "came to china with 5 shirts, so my case was empty"
Thomas is an exception!!! (At least so I've heard) the audio industry in HK is NOT the same as in China (you can hardly believe). I speak here as a humble consumer! you want quality go to HK where the guys will be at least as interested as you. You want a good price go across the 'border' to Shenzhen... and keep your shirt on...
Hope I'm not selling you short there Thomas. (or over doing it)
BTW that little Yarland amp is a cracker - I've said it before. Although I cant really justify another,l I'm thinkin about it they are THAT much fun.
For OPT's the Chinese amps seem to be OK - buy a KT88 amp,if you wanna drive EL34's. But you still might be lookin at $200 for the whole thing. OK - I know you guys in the US might get better domestic deals than us limeys, but $200 us for a decent st of OPT's is unheard of (anyone knows better I need to know!!!!!)
my GENERAL experience is that the Chinese OPT's are not bad but the power trafos are always HOT. Ok I tend to look at KT88 etc. so the current hungry end of things. Still odd that its the boring end of things that get warm?
Actually I'm thinking about this I might get my deerstalker on and do a bit of investgatin' next weekend. Thomas you must have heard hundreds of these any you' would like to recommend?
Andy "came to china with 5 shirts, so my case was empty"
Not all are the same...
Well, the op-trafos in mine are s****...but it runs barely warm, not hot!
http://www.diyaudio.com/forums/showthread.php?postid=1124955#post1124955
Arne K
Well, the op-trafos in mine are s****...but it runs barely warm, not hot!
http://www.diyaudio.com/forums/showthread.php?postid=1124955#post1124955
Arne K
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