Author Topic: A couple of interesting and inexpensive i/v valve output stages  (Read 42173 times)

Offline mcb

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Re: A couple of interesting and inexpensive i/v valve output stages
« Reply #60 on: August 17, 2011, 07:38:37 PM »
Just curious, what are the decoupling capacitors for the dac chip?  Wet tantalums? Polycarbonates?  Do you know the values?  Beautiful wood case!

Good question regarding the caps.  I would need to take the board out to be able to read what is on them.  Gordon (ozcal) has a photo, which he will post in due course.

Yes, the case is something else.  It is a prerequisite that any mods we come up do not require the case to be replaced!

Offline zenelectro

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Re: The latest fad
« Reply #61 on: August 17, 2011, 07:51:21 PM »

WRT the dig side of KD:

You could redesign it with strict EE practices, using multiple bypass ceramic caps + low esr electros, etc and end up with much worse sound.

The chip itself internally is not like modern Cmos IC's and so needs to be treated a little differently. I've been looking at the whole dig/DAC board now for a while
and how to get the absolute most out of it. There can certainly be improvements - or so we might think!

WRT power supplies, every body on this or that forum throws fancy adjectives around to describe the results of their latest power supply
be it shunt regs, ultra low noise super regs, simple series pass regs etc etc. So what -is- the optimum requirement for regs applied to a DAC? Low Z, wide BW, low noise,
shunt operation, series operation? I have a pretty good idea which direction to head based on experience but just following the latest and greatest fad that
is sweeping the net on DAC power supplies is not the answer.

Here's an example, years ago I was involved in designing an amp that was pretty esoteric. It had series pass regs for the front end HT supply. One night I bypassed
the regs altogether and just left raw RC filtering. Result - much better and transparent sound - in that particular application. So much for regulators!

Experience has shown that slow evolution based on careful trial and error with long term listening in a system that is of the highest quality is the way forward.
Experience has also shown that traditional EE solutions don't always translate into better sound. There have been many times when Steven has tried design
changes that I thought were technically not the best approach which translated into better sound.


cheers

T

Your points are well taken and one can get consumed by chasing the latest and greatest fad or trend and go backwards.  I do not think that there would be any disagreement among most that the venerable TDA1541A chip benefits from better power supplies than the rather simple and antiquated 30 year old designs around when the chip was introduced.  The question I suppose is what are the best imporvements that can be made.


As I stated above I have been looking at the KD dig board and where to go from here.
There are many options WRT discrete regulators, types of bypassing, caps used for bypassing, layout, DEM reclocking, etc. 
But the bottom line is, as I did try to explain, it's not so much what all the individual elements are, it's how they work together to get a truly superlative result.

Quote

Given that a lot of water has flowed under the bridge since this chip was first produced, there are many people who have spent years trying to optimize the implementation.  These include but are not limited to Thorsten Loesch, Pedja Rogic and the rest of the ususual suspects.  Their work and observations are in the public domain for all to see. 


More or less. Thorsten is pretty active / outspoken on forums and has graciously given a wealth of info for people to draw on.
Having said that - you won't see any schematics or intricate details on his -real- cutting edge designs which are of course AMR - and for god reason.

Quote

They al stress the importance of optmization of the digital power supplies and they seem to generally advocate the use of tight regulation, often using shunt regulators.  Offhand, I am not aware of anyone now suggesting to go back 30 years with a simple power supply design.  To the contrary.


I didn't suggest going back 30 years. My example of reg versus non regulated HT for power amp was just one case to show that things don't always
work the way we think they will and it's always good to think outside the box.   

Quote

Again, in a general sense, I agree with your point of view.  However, with respect to the power supplies for the TDA1541A dac, the overwhelming if not unanimous weight of opinion, learned from decades of research and experimentation, is to the contrary.  Also, my limited experience messing about with this chip bears out the observation that these improvements reap worthy benefits. 


Please go back and -read- my post again. I'm not suggesting that the KD doesn't require good power supplies - it already has them. Separate regulation
for all circuit elements and the noise is already low. Low noise shunt regs were tried KD's years ago but Stevens best results did not come as a direct result
of them or any other 1 element in isolation just the combination of elements.

Offline ozcal

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Re: A couple of interesting and inexpensive i/v valve output stages
« Reply #62 on: August 17, 2011, 07:55:20 PM »
Apparently Thorsten still uses a modified Satch in his home system. :)
The psu  on his home Satch is simplified by comparison to stock but also uses local shunt regs next to the digital chips.
« Last Edit: August 17, 2011, 07:57:41 PM by ozcal »
Listening with my ears :)

Offline omodo

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Re: A couple of interesting and inexpensive i/v valve output stages
« Reply #63 on: August 17, 2011, 08:08:37 PM »
Below is one of my current favorite sounding implementations of the legendary TDA1541 chip that I have been fortunate enough to try on my system (Zanden Model 5000 MK IV)  Not sure what all those magically coils do, but they work very nicely together :)


The zanden output stage is described in their patent

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6721427.PN.&OS=PN/6721427&RS=PN/6721427

Offline gthicm

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The sum of its parts
« Reply #64 on: August 17, 2011, 08:12:56 PM »
Z,

I do understand where you are coming from when you say that is the sum of its parts that makes the whole.  No doubt that is true, but in a certain context.  For example, a preamp that colors one way is offset by an amp that negates the coloration seems a strange way to go.  The more loical and efficient way to go is to optimize each component and then make small adjustments.  It is not unlike the discusion concerning volume controls.  Some like Alps pots because of the coloration they introduce.  When stepped ladders are used, some people do no like what they here.  Better to then hunt down other issues than discard the better attenuator.  That is my philosophy,for what it is worth.

Of course I am not asking for details such as exact layout and component values.  Other people, such as Thorsten, do give some general comments concerning layouts but not all the details.  I guess what I was asking was what the layout of the digital section looked like.  A picture would suffice for what I was asking.  Any issues with that?

I do not think there is any consensus on regulated versus non regulated HT supplies, say for example on 300Bs.  I prefer regulated.  It is not unlike the discussions respecting AC or DC filament supples for DHT.  I prefer DC as I have not heard a big difference in sound, but DC is quieter consistently.

I am not sure what your point is regarding the digital power supplies.  I guess that I refer back to the beginning to what I perceive to be the best approach.  Different strokes for different folks!




Offline kajak12

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Re: The sum of its parts
« Reply #65 on: August 17, 2011, 08:17:36 PM »
 Some like Alps pots because of the coloration they introduce.  When stepped ladders are used, some people do no like what they here.  Better to then hunt down other issues than discard the better attenuator.  That is my philosophy,for what it is worth.
The best attenuator is no attenuator even stepped attenuators have a colouration by the resistors used choose your poison this is my philosophy
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline gthicm

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Minimalism
« Reply #66 on: August 17, 2011, 08:23:27 PM »
 Some like Alps pots because of the coloration they introduce.  When stepped ladders are used, some people do no like what they here.  Better to then hunt down other issues than discard the better attenuator.  That is my philosophy,for what it is worth.
The best attenuator is no attenuator even stepped attenuators have a colouration by the resistors used choose your poison this is my philosophy
Sure, as it would be best not to have to amplify sound through a bunch of stuff.  Want to go back to the gramaphone?  The best sound is no sound.  One hand clapping? 

Most people need to have an attenuator in the system.  Resistors may color the sound somewhat, but I suggest a whole lot less in an L Pad configuration where only two resistors are switched in at a time.  But if you believe that in the hookup wire there is a different sound signature from new copper, old copper, silver, silk insulation and so on, then anything is totally colored.

Offline zenelectro

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Re: The sum of its parts
« Reply #67 on: August 17, 2011, 08:49:45 PM »
Z,

I am not sure what your point is regarding the digital power supplies.  I guess that I refer back to the beginning to what I perceive to be the best approach.  Different strokes for different folks!


My point WRT dig supplies is there are dozens of approaches to dig layout, bypassing and regulation. They are all different and all have various proponents.

A specific example:

Some people say the Paul Hynes shunt regs are superior to all, others say the same about Teddy Pardo Regs.
Both are high performance regs that are being used successfully for applications from TDA1541 DAC's to Sabre DAC's.

The electrical characteristics of these two regulators are very different.
One has high OP impedance the other has very low. One has very flat impedance curve the other is more rising at HF's
One is a shunt the other is a series pass. One is 'open loop' the other has very high loop gain. They both have different settling times etc etc.

So which one to use?

I am pretty sure each reg was preferred more as a result of how it worked within the context of the complete dac design  
as opposed to any magical characteristic each had in isolation.  




Offline kajak12

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Re: Minimalism
« Reply #68 on: August 17, 2011, 08:54:51 PM »
 Some like Alps pots because of the coloration they introduce.  When stepped ladders are used, some people do no like what they here.  Better to then hunt down other issues than discard the better attenuator.  That is my philosophy,for what it is worth.
The best attenuator is no attenuator even stepped attenuators have a colouration by the resistors used choose your poison this is my philosophy
Sure, as it would be best not to have to amplify sound through a bunch of stuff.  Want to go back to the gramaphone?  The best sound is no sound.  One hand clapping? 

Most people need to have an attenuator in the system.  Resistors may color the sound somewhat, but I suggest a whole lot less in an L Pad configuration where only two resistors are switched in at a time.  But if you believe that in the hookup wire there is a different sound signature from new copper, old copper, silver, silk insulation and so on, then anything is totally colored.
Bingo everything has a colouration your learning
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline gthicm

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Re: Minimalism
« Reply #69 on: August 17, 2011, 09:14:07 PM »
 Some like Alps pots because of the coloration they introduce.  When stepped ladders are used, some people do no like what they here.  Better to then hunt down other issues than discard the better attenuator.  That is my philosophy,for what it is worth.
The best attenuator is no attenuator even stepped attenuators have a colouration by the resistors used choose your poison this is my philosophy
Sure, as it would be best not to have to amplify sound through a bunch of stuff.  Want to go back to the gramaphone?  The best sound is no sound.  One hand clapping? 

Most people need to have an attenuator in the system.  Resistors may color the sound somewhat, but I suggest a whole lot less in an L Pad configuration where only two resistors are switched in at a time.  But if you believe that in the hookup wire there is a different sound signature from new copper, old copper, silver, silk insulation and so on, then anything is totally colored.
Bingo everything has a colouration your learning
Haha.  I am not learning, I have learned.  What I said and have learned is that you believe everything adds coloration.  I do not dearly hold that same belief.

Offline kajak12

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Re: A couple of interesting and inexpensive i/v valve output stages
« Reply #70 on: August 17, 2011, 10:57:56 PM »
Below is one of my current favorite sounding implementations of the legendary TDA1541 chip that I have been fortunate enough to try on my system (Zanden Model 5000 MK IV)  Not sure what all those magically coils do, but they work very nicely together :)


The zanden output stage is described in their patent

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=6721427.PN.&OS=PN/6721427&RS=PN/6721427
That is a very good dac i heard it a few years back on my system
still discovering the link between electronics and audio reproduction.so much to learn and so little time

Offline gthicm

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Shunt reg sources
« Reply #71 on: August 18, 2011, 08:11:04 PM »
Thanks G . Just for interest sake do you have any liks to the shunt regulated dacs you mention ?
Sorry for the late reply.  Got consumed with work.  A possible easy solution would be to get a three legged shunt regulator from Paul Hynes.  He makes some really terrific power supplies as well.  The other thing is to try this guy   http://www.quanghao.com/category.php?id_category=22# .  I have met him in Hanoi and he is really very nice and acccomodating.  He can help you witht he Salas stuff.

Offline ozcal

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Re: A couple of interesting and inexpensive i/v valve output stages
« Reply #72 on: August 19, 2011, 11:52:30 AM »
Thanks G , will look into those.
Listening with my ears :)