Buffalo II & transformers - Page 46 - diyAudio
Go Back   Home > Forums > Commercial Sector > Manufacturers > Twisted Pear

Twisted Pear Superior quality electronic kits

Reply
 
Thread Tools Search this Thread
Old 6th April 2013, 01:10 AM   #451
diyAudio Member
 
Joe Rasmussen's Avatar
 
Join Date: Jan 2003
Location: Sydney, Australia
Send a message via MSN to Joe Rasmussen
Quote:
Originally Posted by mars2 View Post
The only doubts I would have are about noise
True, that is part of the mix too. Especially with tubes it can be. In my case 3R is very acceptable, but it may not be in all cases.
__________________
The "Elsinore Project" DIY Speaker System
Custom Analogue Audio - we also support and promote non-profit DIY
  Reply With Quote
Old 30th May 2013, 03:43 PM   #452
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
Sorry but that is a completly wrong way to output a dac chip.
I dont want to be rude, but please consider following facts,
First:
the reactive element like interstager has to be driven by the VERY low resistance
generator. Which dac chip is NOT. theese 200ohms are simply much to high.
And, dthe very same dac chip is not ment to be the driver of anything but only a DAC...
Second:
the hard step up transformer have a lot of capacitances
because on the output we have large #n secondary turns which have lerger capacitances + on square x C of the primary layers... Tis capacitance deserves very low internal resistance driver before. And it is the problem to compensate large capacitances at the output...
third:
this arangement is after all not have capability to drive the next stage like preamp
even with low electrodes capacitances like tube.
And these topology have all the same sound signatures.
.
forth:
in the topology of the Riv + transformer at very end of the dac
current is partially converts trough the Rdc of the primarry inclouding the reactive
load to the DAC chip directly.
fifth:
if the buffer have very low resistance, thereis no need to use higher primary inductive transformers, so the less turns in primary is needed, and capacitances are decreasing rapidly like allover reactive range... Note: 2sk170 has 40 ohm rds on, which is 5 times smaller value then dac chip has.
...
there is more but there are some basics.
.
The solution is to:
1. convert current after dac chip
2. use low input capacitance + very low output resistance buffer
3. use 1:1 intrestage transformer
4. after the transformer use gain unit
5. buffer on se output to drive the cables, and preamp
...
the main point is that DAC chip and interstage should be separated with a buffer
and the interstage is preferably 1:1 or not high step up ratio
gain has to be acheived with some amplifinig device not the interstage
the role of the interstage is to put galvanic isolation, and to merge down the phases for the SE output from ballanced.
...
cheers
__________________
###
  Reply With Quote
Old 31st May 2013, 01:58 AM   #453
diyAudio Member
 
Joe Rasmussen's Avatar
 
Join Date: Jan 2003
Location: Sydney, Australia
Send a message via MSN to Joe Rasmussen
Hmmm... some rather dogmatic statements there. A bit too Black and White.

I am going fishing... back on Monday...

Cheers, Joe
__________________
The "Elsinore Project" DIY Speaker System
Custom Analogue Audio - we also support and promote non-profit DIY
  Reply With Quote
Old 31st May 2013, 08:35 AM   #454
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
enjoy fishing
sorry there is no dogmatic in my statements
everything argumented, and could be checked by calculations, spice simulations, measurements, and listening tests.
.
ideologic is laying rather in the concept using a interstage transformer
without proper drive, termination and compensation.
using a reactive element without measuring the coupling factor
and all basic things like primary indictance, eventualy capacitance and so
to determine neded drive minimum output resistance...
that story repeating trough the years and can be called black-white?
...
another thing to add
the galvanic isolation with interstage transformer is complet
ONLY if it is present galvanicaly separated power supplys for active units before trafo and after the trafo...
So AVCC 3.3V and electronic after the dac, but before interstage, can be suplyed from one power trafo branch, and all the modules after the interstage should be suplyed with another power transformer PS unit.
.
more that could be of use:
I did 2 switches in addition,
first to swich chasses fround schucko to the chases or lifted off,
another to choose connection of the audio ground possition
(with isolated transformer-chasses) to ground at primary side or to ground secondary side. In my case there is no any hum in any position of the ground switches.
...
also digital branch should have own PS with own transformer
with parallel RC network of 1meg ll 100nF from digital ground to shucko TAP power
(does not have to be tha chasses in same time, because of the simple switch shucko tap lifted from the chasses i mentioned before...)
from the dac side. if it is not some AC value will be present between the power transformers cores and it is also notiable with the scope... With EI cores it is easy to measure
but toroid cores should have a wire from the core to outside to measure this.
...
cheers

happy building, listening
and sorry for the long inputs
__________________
###

Last edited by Zoran; 31st May 2013 at 08:40 AM.
  Reply With Quote
Old 31st May 2013, 09:13 AM   #455
diyAudio Member
 
Joe Rasmussen's Avatar
 
Join Date: Jan 2003
Location: Sydney, Australia
Send a message via MSN to Joe Rasmussen
Quote:
Originally Posted by Zoran View Post
enjoy fishing

...that story repeating trough the years and can be called black-white?
... another thing to add the galvanic isolation....
Amen on the positive aspects of galvanic isolation - but most won't know what you are talking about.

Still here, loading up the car and was just about to turn the computer off...

Maybe I was a little rash, but I like to think I am a free thinker and sometimes able to get things done by thinking outside the square - interstage stuff does indeed interest me, a lot in fact, and maybe I think a little differently. I do roll my eyes when somebody tells me on the phone about a problem, that they have been told by somebody else, that it was caused by an "impedance mismatch" - oh boy, does that throw-away line hide quite a few sins.

Off to catch that Snapper...

Cheers, Joe
__________________
The "Elsinore Project" DIY Speaker System
Custom Analogue Audio - we also support and promote non-profit DIY
  Reply With Quote
Old 4th June 2013, 08:33 PM   #456
mars2 is offline mars2  Switzerland
diyAudio Member
 
Join Date: Dec 2003
Location: Basel
@Zoran:
...puuhhh , I really have my troubles to follow your statements whose form reminds me of preaching.

Quote:
Originally Posted by Zoran View Post
Sorry but that is a completly wrong way to output a dac chip.
..but I see that you found your way.

So there`s really nothing left to say as Amen (with a little bow...)
__________________
none
  Reply With Quote
Old 7th June 2013, 02:51 PM   #457
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
Hi mars2, put in the way You like to, but these are the facts
I wroted, and I didnt have a notion to disturb anyone from personal
tryouts.
.
just one more fact to add:
Passive simple Riv I-to-V conversion
with a single resistor used = phase shift of voltage
so vhen on +Iout loads Riv the -Vout is expected
and for the +Iout = -Vout is after the Riv
...
There is more ways to converting current to voltage
some of them are to put I buffer after the dac chip
sum all Iouts from the same phases, and then
externaly convert this current to voltage, following the buffer low impedance stage,
then interstage trafo, again SE out buffer and RCA conn.
__________________
###
  Reply With Quote
Old 7th June 2013, 04:21 PM   #458
diyAudio Member
 
Joe Rasmussen's Avatar
 
Join Date: Jan 2003
Location: Sydney, Australia
Send a message via MSN to Joe Rasmussen
Quote:
Originally Posted by Zoran View Post
There is more ways to converting current to voltage
Absolutely!

It's all about management, there are going to be a number of variables, some pluses, others minuses, and the best balance and identifying degrees of importance, these will all affect the outcome.

I do NOT favour "virtual earth" solutions, even though on paper they seem desirable to some. They rely on large amounts of feedback in an environment that is ripe for slew rate type distortion. Indeed one well-known designer told us that it is one of the primary causes of "digital sound."

Passive I/V has near infinite overload characteristics, are easy to apply passive filtering (especially if you establish a dominant pole) and using low-noise and even zero feedback circuits (like the types we use in Moving Coil Phono Stages), we have a real high-end solution where the positives outdoes the negatives. The fact that such a solution can also implement DC circuitry and no capacitors, easy with the ES9018 as it can be pulled to ground safely, unlike many other DACs.

Cheers, Joe
__________________
The "Elsinore Project" DIY Speaker System
Custom Analogue Audio - we also support and promote non-profit DIY
  Reply With Quote
Old 7th June 2013, 05:52 PM   #459
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
for the passive filtering i am using if there is a need for
zanden style LRC multi network.And that is depemding on a chrs of the interstage transformer.
.
And i think that You pointed right. Why use transimpedance OP circuits on the end
when we was listened to them for last decades in a same way from 99% of digital equipment?

When I asked Dustin Foreman long tme ago about the Riv issues.
He said simply, put whenewr you want gnd, or +Avcc, os some +Vref in between...
So this dac has no classic output stage like old type models where the offset is have to be low.
.
I spot significant improvement in sound when I change to NON-inductive-hand made resistors from isotan wire...
But maybe it is a subjetive impression?
.
__________________
###
  Reply With Quote
Old 8th June 2013, 04:13 PM   #460
mars2 is offline mars2  Switzerland
diyAudio Member
 
Join Date: Dec 2003
Location: Basel
Maybe you won`t believe it Zoran, and sure there are also subjective resp. psychological reasons:

I tried the Isotan (have an old bobbin of 0.1mm one at hand) - it sounds very good.
When you have a piece of for example 0.1mm (or even thinner) copper wire
or to top the whole silver wire - provided that you have a top clock, separated supplies, careful grounding ans so on, as it is seems the case in your project.

This will bring things to light and shine out...
__________________
none
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Buffalo II Russ White Twisted Pear 1841 13th September 2014 01:28 PM
Volumite for Buffalo II? markusA Digital Line Level 15 8th April 2010 03:51 AM
Need help selecting an I2S/DSD/SPDIF connector for my impending Buffalo II orpheus Digital Source 0 9th February 2010 09:03 PM
FS- Twisted Pear Buffalo 32S Board & System New & Unused secretriches Swap Meet 1 10th August 2009 03:17 PM
Citation II output transformers dshortt9 Tubes / Valves 10 12th December 2003 04:45 PM


New To Site? Need Help?

All times are GMT. The time now is 04:56 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2