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Output transformers for DACs
- Thread starter bisesik
- Start date
I have been using those transformers for a while in an ancient Sony CDP that contains a CXD2552Q2 D/A chip - I know, old technology - but I have always liked the big soundstage created by that player. Once I started tinkering with my gear I tried a variety of CDP mods - different capacitors, bypassing the output stage after the opamps - and, as a matter of course, different opamps - all the way to discrete ones (manufactured by two different companies).
Well, to cut a long story short - I was introduced to Ivan's transformers in a friend's project - and as it takes a bit longer than expected to replicate it - I decided to use the transformers in the above mentioned CDP - and - there is no way that I shall ever go back to any opamp - the only way that comes to mind to describe what the transformers have done to the music is - taking away any digital artifacts (for the lack of a better word). CDs - especially well-recorded ones - sound simply more natural without any digital "harshness" - and those that are less well recorded? Well, they sound the way they are, but still a lot better than before - and some even far less thin that I had always believed. So, yes, I am a very happy customer and the next step is going to be getting those trannies that can be used with a TDA1541 player.
Well, to cut a long story short - I was introduced to Ivan's transformers in a friend's project - and as it takes a bit longer than expected to replicate it - I decided to use the transformers in the above mentioned CDP - and - there is no way that I shall ever go back to any opamp - the only way that comes to mind to describe what the transformers have done to the music is - taking away any digital artifacts (for the lack of a better word). CDs - especially well-recorded ones - sound simply more natural without any digital "harshness" - and those that are less well recorded? Well, they sound the way they are, but still a lot better than before - and some even far less thin that I had always believed. So, yes, I am a very happy customer and the next step is going to be getting those trannies that can be used with a TDA1541 player.
Sure, I can make 1:0.5+0.5 or 0.5+0.5:0.5+0.5 (if the DAC have differential output and center point is needed) version of turns ratio for your choice. You will connect coils different ways to provide SE or BAL outputs. It is extra 10USD to the cost of standard (1:1) version.
dubai2000 Simple and understandable
Thank you!I have not tried 9038pro, but for 9018s I am using 1:4 in SE version. For the BAL output there will be 2+2, but for the primary coil you can use 0.5+0.5 or 1 for your choice. So yes 0.5+0.5:2+2 is OK to use anyway.
In case of ES90x8 chips there is no need to use grounded center point between + and - of the signal. Moreover my expiriences says me that avoiding tighting somehow to ground of the output signal from DAC (if it is possible) is better for SQ. There are some DACs that have + and - of the signal with respect to the ground (like PCM1792) - and in that case there will be no sound at all, untill you not connected to the ground. Say if you can avoid summing stage then no need to split the load. So in case of ES90x8 or AK449x - there is no need to "watch the ground". You can but not necessary.
Yes, it is for the customers choice.
The whole sound amplitude will be splitted for two waves. That is it. I believe there is no any impact to the sound quality inside my transformers while splittering coils because of toroidal type of the core I use in my transformers like it happenes in non-symmetrical types of cores.
In case of ES90x8 it is prefered to use primary coils with as lower active (DC) resistance as possible because I believe the Voltage mode of ES90x8 is only for sound checking (works/not), but the only really high SQ mode is the current mode.
In terms of low DCR the primary coil in my transformer I can make is about 20H. In this case 1:1 will be quiter than 1:4.
1:1 is better than 1:4 in terms of transformers specs (FR, slewrate etc.) but the louder sound level you can grab from your DAC without FR losses the better will be SQ (as far from noise flor as possible). So 1:4 is a good compromise between DCR/winding length and resulting FR and amplitude level.
They arrived today,
I have been trying to understand the whole thing better since
this didnt fully answer my question and im quite curious:
the 8k I/V resistor is converting current to voltage (i.e amplitude).
Wouldnt a 1:1 transformer with 2k resistor result in the same voltage level
with better specs of 1:1 transformer?
Is is that you are aiming for the ''sweet spot'' with transformer roll-off around 20Khz instead of the widest FR, avoiding filtering after the transformer?
Also should I naturally use higher (32k) i/v resistor with 9038pro (4x output) and 1:4?
as you say it will require some tweaking but that would be logical starting place?
I have been trying to understand the whole thing better since
this didnt fully answer my question and im quite curious:
So the 1:4 transformer is trading current for voltage,
the 8k I/V resistor is converting current to voltage (i.e amplitude).
Wouldnt a 1:1 transformer with 2k resistor result in the same voltage level
with better specs of 1:1 transformer?
Is is that you are aiming for the ''sweet spot'' with transformer roll-off around 20Khz instead of the widest FR, avoiding filtering after the transformer?
Also should I naturally use higher (32k) i/v resistor with 9038pro (4x output) and 1:4?
as you say it will require some tweaking but that would be logical starting place?
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Laserscrape, if the sensetive of the next stage (amplifier) is ~2V and the impedance is high (~50k for example) to achieve full power, then your impedance (resistor) value at the secondary should be 1.8kOhm in total. So, try to use 1k-2k shunt to be synchronised with your amp impedance.
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The DC resistance of the 1:1 transformer used with AK4490 (for example) tens times more and sounds worse with ES.
There is more powerfull LPF in case of ES (or AK) DACs - its inner Digital LPF. My aim is not to add additional LPF if possible.
Yes, you can, but the output level will be respectively high.
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Because there is the limitation by your next stage' impedance. If you will load transformer to the really high impedance like oscilloscope, then you will see the wave level dependance from resistor value adequatelly.
But what if the next stage (amplifier) will be with 1kOhm of input impedance? In our days - it is not so rare case. I think it is not absolutely right to limit output capability of the powerful DAC when it can be more universal for different types of amplifiers including low input impedance models.
Oh, so i had the I/V resistors effect backwards! thats a relief.
With that in mind 2k was still high in volume, 500r is giving about the same output as the old op amp output stage, I use headphones so output level is probably very low.
thanks for helping me out.
Anyway the SQ is instantly appreciatable, very nice and natural sound
About 1:1 transformer, this is what confused me:
The 1:1 you mention here wont have low DCR suitable for Sabre DAC?
EDIT: sorry, you just explained that
With that in mind 2k was still high in volume, 500r is giving about the same output as the old op amp output stage, I use headphones so output level is probably very low.
thanks for helping me out.
Anyway the SQ is instantly appreciatable, very nice and natural sound
About 1:1 transformer, this is what confused me:
The 1:1 you mention here wont have low DCR suitable for Sabre DAC?
EDIT: sorry, you just explained that
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What is the sensitivity (in Volts) of your amplifier to achieve the maximum output level?