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BTH K10A
20-03-2011, 21:00
About 10 years ago I heard reports from the far east on the effect putting Western Electric 111C or 119C repeating transformers beween CD and preamp.

http://i46.photobucket.com/albums/f120/emttsd15/WE119C.jpg

I must admit I was a little sceptical especially with no chance to audition. At the time I had never been as satisfied with CD as I as with vinyl and when I saw a pair of cased 119C's on Ebay Germany for a reasonable price I took the plunge.

A pair of 119C transformers were put into neat little case in Japan.
http://i46.photobucket.com/albums/f120/emttsd15/IMG_0854.jpg

Input / output labels are a bit awry but the ones on the switches are correct.
http://i46.photobucket.com/albums/f120/emttsd15/IMG_0853.jpg

With hindsight this is one of the best bits of kit I've ever purchased. CD and for that matter any digital source sounds more analogue.

I don't know if it's impedence matching, an effect of the transformer windings or something else, but I don't really care. All I know is that it's effect is magic to my ears and for CD I wouldn't be without it.

The only empirical data I can find is in this link
http://www.cliftonlaboratories.com/non-linear_transformer_behavior.htm#Western_Electric_1 19C_Repeating_Coil_Frequency_Response

Barry
20-03-2011, 21:51
Curious that adding a unity gain device should improve matters, unless it's acting as some sort of filter to remove 'digital' hash. Yet the Western Electric trannies appear to have a very wide frequency response. Not bad for a 40 year old design though. A lot of transformer 'know how' has been lost; unfortunately it's no longer taught.

Will have to think about it a little more.

Regards

Rare Bird
20-03-2011, 22:46
How much was it Andy if you don't mind me asking?

BTH K10A
20-03-2011, 23:15
90 Euros in 2002 Andr'e. Mine was the only bid. :)

zanash
21-03-2011, 10:30
you can do something similar ish ....on the digital side .

fit a pulse transformer to the digital cable this will remove some of the hash and clean up the signal trace ....but if you've a poor wave form being outputed then no ammount of filtering will help !

BTH K10A
22-03-2011, 21:28
Curious that adding a unity gain device should improve matters, unless it's acting as some sort of filter to remove 'digital' hash. Yet the Western Electric trannies appear to have a very wide frequency response. Not bad for a 40 year old design though. A lot of transformer 'know how' has been lost; unfortunately it's no longer taught.

Will have to think about it a little more.

Regards

Hi Barry, Discussed this today with a work collegue who's a telecoms engineer. He said that high pass filters in CD players only reduce the DC offset that all AD / DA converters have. He said the transformer will totally remove it and other nasties, but you need to use a top quality high bandwith transformer to maintain the integrity of the signal, and that the transformer wouldn't be cheap.

Don't know if he's right, it sort of sounds plausible but I can't see how it would make the music more "analogue" sounding.

Andy

hifi_dave
23-03-2011, 18:38
Many, many years ago, I bought a job lot of Marantz DLT-1 transformers. This stands for Digiital Line TRansformer and was a high quality 1:1 transformer, designed to be inserted between any line level equipment, like a CD player to amp. Marantz UK had no knowledge of the product and I was persuaded to buy in bulk because they were unsure.

The resultant sound was astonishing and we quickly sold all 40 of those imported, all but one which went to Jimmy Hughes, We used to demo it against the DAC's of the time like Meridian, Deltec, Theta, Roksan etc, etc and it always won hands down and was often a fraction of the cost of the DAC's.

I believe that DSJR still has one.

Reid Malenfant
23-03-2011, 19:09
Hi Barry, Discussed this today with a work collegue who's a telecoms engineer. He said that high pass filters in CD players only reduce the DC offset that all AD / DA converters have. He said the transformer will totally remove it and other nasties, but you need to use a top quality high bandwith transformer to maintain the integrity of the signal, and that the transformer wouldn't be cheap.

Don't know if he's right, it sort of sounds plausible but I can't see how it would make the music more "analogue" sounding.

Andy
Hmmm, i think you'll find that virtually every CD player will have an AC coupled output via a capacitor so there should be zero DC offset. Some so called "high end" DACs or players may well be DC coupled but it'll likely be done with a servo which will create miniscule amounts of noise at 1Hz or lower..

However, all CD & other digital stuff is playing joint the dots at the end of the day :eyebrows: Some oversample in an attempt to create more dots if you like to smooth things out more, this is where i think the transformer does it's trick ;) Inductors (& capacitors) tend to store charge & don't like rapid shifts in voltage, after all they only have a certain bandwidth, my guess is that if you looked very closely at the AC waveform of the output of a sine wave from a CD player you could possibly see where each sample or "dot" has been joined to another.

A transformer would smooth this much more due to the things inherent nature & this may be where it scores highly :) Just a thought & i have no proof of it, but it does make a good bit of sense i think :scratch: :lol:

Barry
23-03-2011, 23:01
Hmmm, I think you'll find that virtually every CD player will have an AC coupled output via a capacitor so there should be zero DC offset. Some so called "high end" DACs or players may well be DC coupled but it'll likely be done with a servo which will create miniscule amounts of noise at 1Hz or lower..

However, all CD & other digital stuff is playing joint the dots at the end of the day :eyebrows: Some oversample in an attempt to create more dots if you like to smooth things out more, this is where i think the transformer does it's trick ;) Inductors (& capacitors) tend to store charge & don't like rapid shifts in voltage, after all they only have a certain bandwidth, my guess is that if you looked very closely at the AC waveform of the output of a sine wave from a CD player you could possibly see where each sample or "dot" has been joined to another.

A transformer would smooth this much more due to the things inherent nature & this may be where it scores highly :) Just a thought & i have no proof of it, but it does make a good bit of sense i think :scratch: :lol:

That's my understanding. Furthermore, most amplifier inputs use a series coupling capacitor, if only not to upset the biasing arrangements of the first stage.

However if I find a couple of broadband 1:1 transformers in my junk box, I might give them a try.

BTH K10A
23-03-2011, 23:54
Don't coupling caps only reduce any DC offset, albeit to very low levels. DAX used to make a point of this when extolling the virtues of servo coupling or was this just marketing hype.

Reid Malenfant
24-03-2011, 11:05
Don't coupling caps only reduce any DC offset, albeit to very low levels.
Yes, as long as the capacitor doesn't "leak" then it should reduce DC offset to the inherent value of the following equipment. Servos are generally used to reduce this further still, or as you point out on DC coupled gear.