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Not sure if this is the right fora (if not, pls advise) but here is my dilemma:I've heard from a friend that Stevens & Billington TX-102 trannies used in many TVCs around (MF, Bent, Django etc) are with EI-core.
Is this true? I would expect - considering their SOTA status - that they are double-C core because its electric qualities are much higher.
I also believe that the shape of the core has much more influence on sound than material it's made of (permalloy, nickel, iron, whatever).
I can't check this visially as they have a shielding shell so i would much appreciate if anyone can clarify this.
Follow Ups:
Contact John Chapman at Bent Audio. He is a very knowledgable engineer, and will likely take the time to thoroughly answer your question.
You could try the contact button at the bottom of this page :
http://www.stevens-billington.co.uk/pagehifi.htmOr you could try asking in the forum where they build the Django :
http://www.audioasylum.com/forums/DIYHiFi/bbs.htmlCome back to this thread and let us know what you find. I would like to know what you discover, and why.
Are you saying that a double C core should be better in that particular application just because it's a double C core? I would think that there are other factors to consider regarding quality. Please elaborate if/when you can.
Hi,Meanwhile I have found out that the S&B trannies are EI core too.
EI cores are much cheaper to produce than double-C core, especially if a better material than plain iron is used. S&B uses nickel/permalloy or something like that, not sure.
My interest was based on a curiosity if S&B TX-102 is the best you can use when building a TVC or not.
My suspicion was raised after testing a DIY made TVC with double-C core that sounded clearly better in both subjective (listening pleasure / enjoyment) and absolute terms (more extension in extremes, both HF & LF, more micro & macro dynamic) than an EI-core based commercial product apparently very close in sonics to MF.
This was verified by a bland test performed to a panel of 4 neutral and exprienced audiophiles with clearly no interest in any of the products, except for a plain joy. As I am the owner of the production unit too, I wished it was a winner but it wasn't.
I know several people who sold their MF TVCs after they heard a mentioned product that, because it is 5-6x cheaper and very close in sound. As it was clearly inferior to a DIY TVC with C-cores I was wondering what would happen if we would have the MF TVC to try it.
As MF is usually cosidered a benchmark for TVCs, I am really curious to know if S&B actually compromised some sonic qualities of TX-102 because of production restrictions. What leads me into this direction is EI cores and size of the trannies (old school of thinking says that trannies has to be bigger to have a fuller sound and good freq. extension, as proved in case of another DIY TVC).
If this is the case, why going for a product that is being promoted as the closest you can get to the original sound, when you can actually get substantially closer with just a little more effort in finding someone to wind you a trannie according to well known rules. Every transformer expert will tell you a difference between EI and double C core trannie and why the latter by rule sounds better if properly wound, taking a good care about a balance between a size of the cores and a number of windings.
First of all, I think that all of your questions are very good. These are the kinda things that I think about too. I also think that MSL provides some good perspective to help with your answers. The common sense side of my brain feels comfortable reading his reply to your post.I don't know nearly that much about transformers either, but one thing I do know is that you need to pay close attention to impedance matching. Both the input and the output of the xformer, and the source and load impedance of what it is controling. When you say that you took one TVC apart and substituted with something else that you wound yourself, it makes me wonder if all things impedance wise were still equal. I'm not implying that they weren't, it just makes me wonder. This can have a dramatic effect on the sound too.
I have the Django over here with the S&B tranny and I like it alot. I Iike it more than any active preamp that I have ever owned. That doesn't mean that it couldn't be any better, I know that. I have never heard the MF version or the Audio Consulting either, so I can't comment on those.
But as a listener (consumer?) who is always interested in kicking it up another level, I would be interested in knowing what double C core transformer you are using, where to get one, etc. This might be helpful for others to chime in with their opinions too.
I can't remember if I described the DIY TVC with double-C core transformers I mentioned in my earlier posts.It is actually quite hard to describe it. It's a brainchild of a local audiophile who, being a sceptic in hi-fi industry, rejected audio brands 25 years ago (except for Koetsu cartridges and Tannoy/Lowther drivers;)). Everything in his system is built by different low-key, DIY local gurus, but always to the highest possible standards you will seldomly find in brand name audio, unless you have $$$$$$$$ to pay for flashy displays and shiny boxes.
The guy is trying to use whatever a heritage of 60-70 years of audio is. He is not following any fashion or trends. He has been experimenting a lot with the output transformers for both power amps (SET) as well as for his preamp which is an amazing product, a kind of a true single end design (1 valve per channel) with output trannies. A massive, double mono preamp, 30 kilos of iron and chrome, most of it in output trannies.
He studdied trannies for decades. The output trannies made after his design (on iron cores, wound with copper), outperformed Audio Note trannies.
And he has been mentioning transformers as something that should be used for volume control in passive preamps at least for 20 years, when all the hype about resistor based passive preamps started (Creek etc).
How did he come to double-C core trannies? Simply, any 50s book on trannies will teach you their electrical and magnetic parameters are superior to EI cores. And whenever he had a chance to compare them, it was always a double-C core trannie that sounded better than an EI core one, when all other parameters were similar (size & material). Better - meaning more natural, more detailed, better dynamics and better freq. extension. More music, less veil.
Forgot to mention - he is not building commercial products. He is not selling anything to anyone. He generously shares his views with whoever is interested in. There is a number of products here in a local community that are DIY-ed around his and ideas of his buddies.
Luckily, he is based in a country where labour is cheap and you can still find some old materials around (former Eastern European country). So, it wasn't that difficult to experiment with core geometry, different ways how to wind a transformer, to find an optimal ratio between core size and number of windings etc, and to get some valid knowledge about transformers that is not related to commercial restricions .
Now, after so many years - and in light of the current TVC craze - he decided to give TVC a try. To be more precise, he managed to persuade (after years (or decades) of trying) his friend who is a transformer builder (he has a small tube amp manufacture and he winds his own trannies) to wind him 2 trannies for his TVC.
Of course, such trannies had to be wound strictly according to his own beliefs. Two main ones are: 1) the first core geometry to be tried is the double-C 2) the trannies has to be big, if costs of production and materials allow - because the big trannies simply sounds better - have better dynamics and better frequency extremes, compared to any small tranny.
He is not downplaying the importance of materials used - especially permalloy, nickel or whatever - but he just has no access to cores made of anything but good old plain iron. I will check that out soon but I think that he is actually using old iron cores, left from different DIY project from long, long time ago. He is anxious to try the similar geometry (double-C) with better materials but I am afraid this will take time to find the ones he can afford. People don't have so much money here where he lives. R&D is based on different principles than in the West.
Finally, his technician finalized the first (and so far the only) version of a dual mono TVC, with double-C core trannies, with 2 cheap (but decent) German switchers with 9 position volume only and with 1 input and 1 output RCA stereo connectors worth of $1 (not sure if they are gold plated at all).
This was all assembled just to get a flavour of TVC sound so he can carry on developing, tweaking etc.
So what is the catch here, you are wondering?
Problem is that this Frankenstein of a TVC, worth of $50 in iron and copper plus costs of 6-days labour in winding and assembling, has no room to tweak.
It sounds like a $10,000 preamp. Or like a $20,000 preamp. Or $30,000 preamp. I don't know - I've never such an expensive one, but this really sounds like there is no room for sounding better.
There is nothing to add, nothing to complain, nothing to change, nothing to burn-in, nothing to wait.
After a month since it was completed, more than 25 really experienced audiophiles coming from various schools of audio (SET, FR, tube, digital, SS, whatever) heard it in a number of totally, dramatically different systems, with the similar conclusion whenever it was tested.
This ugly little monster is just leaving everyone speechless.
After long talks we have managed to persuede the owner/designer not to touch this piece anymore, just to leave it as it is and to build another one if he believes that anything else - different switches, wire, connectors, box, windings, trannies or whatever - can make a difference and improve its performance.
To be honest, the main scepticism is if he is capable of building another similar unit because he admits that he just wanted to give it a try to see if the TVC principle is something worth of developing or not.
He didn't involve any serious calculations into his project, no rocket science - just a few plain, old tricks of transformer winding old masters, known for almost a century.
But even him, being extremely critical of almost every audio product out there, including his own, agrees that he now doesn't hear a room for improving its performance.
I know that this sounds just like another audio fairytale (and therefore I will accept any doubt you may have), but I can only say that my only wish is to get this guy somehow make one of these for me, as the last preamp I will ever need in my house....
This is unfortunately not sure yet and it depends on how many of these old, double-C cores still lay somewhere, in a corner of someone's attic.
Anyway, if you are still reading this long post: one day, when S&B, Sowther or any of these big TVC companies finally commercially release a double-C core TVC tranny that will be advertised as "better than anything you have ever heard before", just remember when you read it first.
Why we will have to wait for so long, that's another question whose answer is probably similar to when you will get a mobile phone or digital camera or any consumer product that really has everything an advanced user might need. I don't know, but you will be able to buy "a better", "an advanced" or "an improved" product each year.
Hi Gordon,Thanks for the story. I have no reason to doubt any of it. I will remember that I heard it here first.
While there is merit to what you are explaining, I can tell you from my own experience that consistency in production is not always possible with the state of the art. When I worked in production for a an RF components company years ago, we would occasioally get orders for just 4 or 5 microwave amplifiers that were beyond the limits of possibility. We would try to fill the order anyway. It could take months, or even more than a year to get all 5 of them to work to specification. Usually, someone could get one of them to work and we would try to use that as a benchmark for the others. But this was wishful thinking because we were really maxed out with the technology that was available to us. When we did get them all to "work", you could not get repeatable performance from them on a day to day basis. They were expensive, unreliable, and inconsistent. They were also a lot of fun!
Projects like these help a company to understand what is possible for real production runs, and where to draw the line if they are to stand behind their product. They also help us to take everything else to the next level. This is more in the area of test and development compared to what you would expect from a regular production run of standard products.
Consistency, reliability, quality and value. That is something that we all take very seriously when we click the "add to cart" button.
So what am I trying to say? I don't think it's fair to compare an off the shelf product that is produced in large quantity by a company that stands behind it, with something that a hobbiest was able to make, and only make one of using rare or discontinued materials. I hope you can see the difference.
I also hope that your friend can share his ideas with the rest of the world, and push the quality level up a notch for TVCs. I really like mine, and when I hear a better one I will buy it in a heartbeat. (If I can afford it.)
And I just hope that I will be one of those who are lucky to own one of the pieces that will be ever made.Luckily, as a TVC is so simple - apart from xformers themselves - I think there is a much less chance for any reliability issue.
Everything else you mentioned I fully agree. Right now, the main thing is if the next units - if there will be the next units - are going to sound the same as the first baby;).
But it would be great to have such a wonderful sounding product. A real audio utopia.
PS. From the info I've managed to collect from different sources, S&B are perfectly happy with their EI core transformers made of permalloy and a few mysterious percent of unknown material. Apparently they are aware both C-core and double-C core would sound better, the same goes for a bigger size than a current one... but this is where they have decided to draw a line.
I can only conclude that if you need ABSOLUTE, you have to build it yourself.
*snip* 6-days labour in winding and assembling *snip*Theres your answer. Cost of labour for most things now far exceeds the material costs.
the only thing is that 6 days of labour where this TVC is produced is not more than $250.
Hi Gordan:I read your same post and a reply which Kevin Carter made on the K&K forum. And I agree with Kevin's response, which was;
:::It's rarely true that one particular parameter or component is solely responsible for the sonic success of an audio design. I'm sure that a double C-core TVC could be made to sound inferior to an E-I core TVC.:::
Your oversimplifying a complex product and trying to reduce it's goodness to a single parameter. And it logically can't be done. It's entirely probable that a shitty sounding trans can be built on any of the extant core materials or shapes. And the opposite is equally probable.
I'll address one other issue you raise;
:::EI cores are much cheaper to produce than double-C core...:::
again, this is a simplistic assumption that is surely not a universal truth--
c-cores are generally purchased wound and cut and ready to use. Generally the price of a c-core (in a sense the assembly of which has been done for you) is higher than purchasing X number of pounds of the same material as a punched lamination (say in the shape of an EI).
But... and it is a big but.... once we factor in the total cost of purchasing, stacking, and impregnating the EI laminations into a finished product--- then, depending on the labor costs--- it is often equal in cost or darn, darn close to equaling the cost of using a c-core.
Remember, you can basically use the c-core right out of the box--- the EI's are like buying all the parts to make a car--- but you still have to put all the parts together. Once you factor in the costs of putting the EI lams together--- it's not always the case that the EI was a cheaper alternative--- and sometimes it will prove to be more expensive than purchasing a c-core assembly.
I won't go into the performance issues and benefits-and-disadvantages of c-core vs say EI's... I sense that (from your post) you have already reached your own conclusions.
Also--- the cost matrix I have pointed out above--- assumes use of say a relatively inexpensive core material like M6. Once you start going into the exotics--- the cost differentials btwn c-cores and EI's quickly evaporates since it is the raw materials costs themselves that form the largest marginal cost of the core---
also--- you make the assumption (since you've not had it apart) that S&B is, in fact, using an EI shaped lamination. When in fact there is a wide range of different core shapes that are produced as a punched lamination. UI, F, D, EI, EE, are just a few of the shapes available.
And, as just one example, a UI lamination will frequently have the same F to G ratios as a traditional c-core will have. So that it will have the same path length and the same window area as the c-core which it might replace or be used in place of.
There are some potential advantages to using the punched lams vs a c-core in certain applications. If you go to the MQ forum and do a search--- you'll find posts in which I have explored these same issues.
MSL
Dear MSL,I am very far from your transformers' knowledge and I judge only by my ears.
I was obviously mislead with tons of positive reviews of a certain TVC product and I expected that a substantial sonic difference between different models is not possible. So, while looking for an explanation for such a difference, we stopped at the core geometry as both were made of rather plain (cheap) iron, wound with a rather similar copper wire. We thought it is a core geometry that makes a difference because you will find a lot on different electro-magnetic behaviour of different core profiles.
I have no doubts that there are ways to minimize an inferior geometry through using more sophisticated material, and this seems to be a case with S&B.
I don't want to be misunderstood - I haven't tried S&B trannies yet but I will have a chance in early April, in very carefuly executed TVC that should outperform MF, at least considering other materials used in the preamp apart from the trannies. What really bugs me is what I have explained in my previous post: are S&B 102s something that can not be beaten even with a clever DIY approach, or my experience with a DIY TVC with a different core geometry is something that opens a completely new way of thinking about TVCs.
If this TVC prototype based on double-C core trannies worth of $50 in material and a few days of winding kills the S&B based TVC the way it killed a brand name TVC, I can only conclude that the worldwide TVC community is seriously missing the truth.
Most likely the audible differences you are hearing are down to reduced parasitic capacitance, as the home made cores will be 'scramble-wound' in commercial speak, i.e. irregularly laid on the former. Scramble winding is very very expensive to do, as in general it can only be done effectively by hand.Unless tightly controlled, the airgap in a C-core will also vary substantially, and that will influence the sound dramatically, especially if you have any DC offset at the TVC input.
Audio transformers are where art and science meet - there is good theory that covers 98%, but the remaining 2 % is pure craft.
The fact that S&B produced the damned thing at all is nothing short of a miracle, and it does sound significantly better than an equivalent electronic buffer.
Have fun
Hi,Meanwhile I have found out that the S&B trannies are EI core too.
EI cores are much cheaper to produce than double-C core, especially if a better material than plain iron is used. S&B uses nickel/permalloy or something like that, not sure.
My interest was based on a curiosity if S&B 102 is the best you can use when building a TVC or not.
My suspicion was raised after testing a DIY made TVC with double-C core that sounded clearly better in both subjective (listening pleasure / enjoyment) and absolute terms (more extension in extremes, both HF & LF, more micro & macro dynamic) than a EI-core based production unit apparently very close in sonics to MF. This was verified by a bland test performed to a panel of 4 neutral and exprienced audiophiles with clearly no interest in any of the products, except for a plain joy.
I know several people who sold their MF TVCs after they heard a mentioned product that was beaten on the test, because it is 5-6x cheaper and very close in sound.
As MF is usually cosidered a benchmark for TVCs, it really made me wonder if its design was made with compromises or not. I am really curious to know if S&B actually compromised some sonic qualities of TX-102 because of production feasebility. If this is the case, why going for a product that is being promoted as the closest you can get to the original sound, when you can actually get closer with just a little more effort in finding someone to wind you a trannie according to well known rules. Every transformer expert will tell you a difference between EI and double C core trannie and why the latter by rule sounds better if properly wound.
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