66.172.126.240
In Reply to: RE: Output Transformer for 3.1 Dac posted by fc911c@ptd.net on March 01, 2013 at 17:09:32
As someone who has heavily considered doing this for many years, but have not yet taken the plunge, I can offer the following...
The DAC 3.1 output section has two 5687 tubes each with dual triodes. Each channel has two anode followers in series which generates a lot of voltage gain.
http://www.audionote.co.uk/comp/trans/trans_04_preamp_outputs.shtml
Trans-027 is a 33:1 (primary to secondary turns ratio) pre amp output transformer and is offered at varying degrees of quality and price.
The 33:1 turns ratio functions to convert the high voltage of the output tubes to current. Current is ideal for driving the interconnect and the input of the following device (rather that be a pre-amp or integrated amp).
Using a transformer at the output of any device isolates its grounding scheme from subsequent devices. It also negates the necessity of an output capacitor and all the problems that a capacitor brings.
DC is supplied to the second anode through the primary of the output transformer. Therefore the transformer is doing double duty performing as a choke which further filters the power supply and therefore provides better sound.
Transformers have their downsides as well and are as complicated as anything else in audio. Because of this I would stick with the Audio Note offerings. They are designed specifically for this application and while line stage output transformers from other manufacturers may work, there will likely be trade offs.
As far as which flavor of Trans-027? Well, unfortunately it's a question of how much do you want to spend. Better core materials and silver winding extract more detail and musical energy.
A few years back I invested in the silver wired I/V transformers (Trans-497). I'm happy with the results and it's nice to know I've got that I/V transformer problem solved without wondering if I should have gone all the way. My theory is that the smaller the signal is the more important the quality of the components that deal with it. After all any compromise made to that small signal is then amplified many times as it is carried through the rest of the system.
Eventually I want to go with output transformers with at least silver wired primaries. Having silver on the primary nets better than 50% of the improvement seen by having an all silver wired transformer.
Building a DAC kit that basically amounts to a DAC 5 in terms of component quality is damn expensive, but no where near the cost of having audio note make it. It might take a while but this is the direction I've decided to go.
Follow Ups:
Thanks for your input and your detailed post. Unfortunately my budget is around 1500 so silver is out of reach. The reason I was asking for other options was the AN trans are made to order and could take up to 3 months.
What was the problem you were having with th I/V's?
The only thing I find wrong with mine is the output voltage is low, about 1.5v or lower depending on the source.
Thanks Frank
If I may give some input here. There has to be another manufacturer that can match the specs of the AN transformers. He has them wound and if he can do it so can others, probably for far less $$$$$$$$$$$$$. AN is great stuff but they don't have a market sealed on quality. You have to remember!!! They charge because they have to. If they are getting say $1500 for a pair of transformers then it cost probably 1/3 of that, if that much, to make. Don't get me wrong(as others have). I like their products but they don't have a sealed market on quality and what they build. Their advertising does more and then there are the cult followers of the products.
That output stage is nothing special. I have the schematic for it and it can be built for far less than what AN charges.
So in short, just find out the specs of the tranny and contact Hashimoto, Magnequest, or Bottlehead and see what they have available. Even Heyboer can make to order for very little $$$$$$$$$$$$$$$$.
In short I am more of a favorite of cap coupling. Changes in the sound can be made for far less than the use of a transformer.
I agree with xaudiomanx. I'll take a good cap over a transformer any day--provided the tube has sufficiently low output impedance to drive the load.
Does that mean that my Dac 2.1 with output cap will sound better than the Dac 3.1 with output transformers?
Alan
Good question! There are basically two methods for DAC/ pre-amp output stages and that is a Capacitor coupled stage or a Transformer Coupled output stage as you have gathered - one is capacitive and the other is inductive- both have advantages and disadvantages- hard to say one is absolutely better than the other - its like single ended amps and push pull or 300B vs 2A3 or EL34 vs EL84 - all are good -different approaches - red wine vs white wine - depending on the rest of the system - the capacitors and transformers used - the type of tubes and whether they are nos or new! etc.etc.. Some customers prefer transformer coupling and some prefer the capacitive output stage - AudioNote is heavily influenced by transformer coupling in all things - IV stages between digital and analog , interstages between power tube stages and output transformers in pre-amps and DAC's - thus they have invested alot in R&D in this area and have a huge range c core transformers with various cores and silver copper wire combinations! so its really a matter of listening your self to as much as you can and drawing your own conclusions!
Hello Brian,
Did you receive my E-mail about this same subject?
Mark.
Thanks for your input, something worth considering.
Frank
xaudiomanx,
Totally agree on all points. However, even with the same winding ratio and getting to the desired primary and secondary impedance (which audio note does not define), there are many variables that would have to be considered for another pair of transformers to behave with a similar sonic characteristic as built into the AN transformers and their house sound.
There's a lot of art in making transformers of really high quality and especially when dealing with low level audio signals. Various winding techniques, core gapping, core materials to name a few. Some of the AN transformer designs are unique.
Custom amp builders who have had the time to try output transformers from various manufacturers will talk about the different sonic characteristics they have even though they are designed for the same circuit. And unless you were lucky enough to evaluate and compare them, you will be paying for iron that you'll never know for sure is as good as the AN gear designed for that application.
All that said I'm not denying the possibility that you could buy an off the shelf Lundahl or Magnequest and wind of up with even better sound. I remember an AN DAC kit with lundahl OPTs and they liked the results, but unfortunately hadn't heard AN OPTs to know how they compared.
I think Audio Note could survive while charging much lower prices. The unreasonably high prices for their flagship gear is really the biggest gripe I have with the company. OTOH they've been at it for a long time now and their DAC concept has withstood the test of time.
No problems with the standard I/V transformers. I was just speaking generally in that there are lots of different ways to handle the current to voltage (I/V) conversion from the dac to output stage. Using a transformer is a neat solution.
On the Digital Board: R34 and R35 are parallel to the DAC output signal and ground. The value of this resistor could possibly be increased in order to increase the output voltage.
Looks like TRANS-027/01-AS would fit the bill. Super HiB C-Core should be a solid improvement over the standard I-E core. Hopefully someone who has done this upgrade can chime in.
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: