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Output transformers for DACs

Here is a demonstration of how good enough can digital audio sounds like:



Thanks for video to Kartick (@kartick) who has spent so many time to make his digital chain really good sounding. I know Kartick experiencing some difficulties after incedent with his system but I hope it will be fully restored soon.

p.s. And as it placed in my thread then yes, DAC-source is utilizing my i/v trafos :)


 
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Very nice. Looks like a combination of horns and open baffle?

I’ve tried both and have stuck with OB bass driven with Hypex for a while.

I’ve tried lots of fullrange drivers on OB and in horns with them.

Trying to stick to a point source for as much of the frequency range as I can.

Currently playing Tannoy drivers, but also planning to try some coaxial CDs with horns I have.

Making resistors for the first time with Constantine wire…a challenge with my less than perfect vision and shaky hands.

Been going back and forth between this and new OB panels for the Tannoys.
 

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Hi bisesik

I finally have the transformers installed, wired up and have done a test with music after spending time changing things in my DAC to make it possible.

I am having a problem with buzzing noise coming from the DAC now.

It gets louder as I turn the volume up.

It even causes buzzing in my system when I power the DAC down if I leave it selected as the source.

The only time it goes away is if I select a different source or disconnect the RCA cables from the DAC.

I don’t know if I did something wrong with wiring , grounding or if its how I have them installed in my case?

I followed the example illustration you posted for me (pic) to wire the output of my pair of D3 boards for differential output.

I also searched the D3 thread and used an illustration Ryan posted there (pic) explaining how to make sure the signal cables are connected properly between my I2S to Simultaneous board and D3 boards for balanced output…which I assumed was necessary for differential connection to the transformers.

I removed the 11k iv resistors on the secondaries of the transformers that were installed.

I then installed the wire wound 25 Ohm iv resistors I made on the D3 boards on the primary side of the transformers.

I haven’t removed the current injection resistors and caps on the D3 boards yet. After I installed the new iv resistors I retested and nulled any DC offset at the outputof the D3 boards (it was barely .5 mV).

I’m not sure if I was supposed to bridge or change any of the jumpers on the transformer board (except at the input which I did as you illustrated)…otherwise I left things alone.

I’ve posted some pics of how things are currently installed and connected.

I hope you can help me troubleshoot the problem.
 

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After long reading about transformers I'm about to venture here. I have a couple of questions for those with experience since it appears the majority use NOS or current-output DACs and don't want to bug Ivan direct:

1. My custom DAC boards use AK449x in mono mode. With active filters one does a tradeoff between noise and distortion to sum the two channels with resistors into the high input impedance filter. Did anybody check with AKM DACs in mono mode with transformers for optimal resistor values?

2. Theoretically it may be OK to disable the DAC internal oversampling filter and run it NOS. This however is not easy to accomplish with standard front-end sources without e.g. some FPGA/DSP intervention. Is the expected performance of this AKM DAC series with enabled filters competitive with the alternatives from ESS/TI when using transformers, or is it near-mandatory to run it NOS?

3. Application is a 3way active project i.e. six total channels. This disallows using the JFET buffers because clean enough separate power supplies are too complex. However, passive implementations have shown that the bass usually suffers the most. Would it be an agreeable assumption/compromise to use active on the bass and passive for mid & tweeter?

Regards,
Pierre
 
After long reading about transformers I'm about to venture here...
I am not own the audiophile grade 449x DACs but my answers are based on my own experience with AK449x DACs and on the DIYers/clients feedbacks. So let me comment:p

1. My custom DAC boards use AK449x in mono mode. With active filters one does a tradeoff between noise and distortion to sum the two channels with resistors into the high input impedance filter. Did anybody check with AKM DACs in mono mode with transformers for optimal resistor values?
I wonder how big the difference in sound quality is when deviating from the recommended load impedance?..

Mathematics should be simple. If it is indicated as 10k for a single channel, then it should be OK for 5k per 2 paralleled channels. But anyway there is no the strict relation between the impedance seen by DAC and the SQ after my transformers. Trafos will be simply better regardless of your angle of view as trafos for the AK449x are 1:1 and they do nothing with the impedances seen by DAC.

2. Theoretically it may be OK to disable the DAC internal oversampling filter and run it NOS. This however is not easy to accomplish with standard front-end sources without e.g. some FPGA/DSP intervention. Is the expected performance of this AKM DAC series with enabled filters competitive with the alternatives from ESS/TI when using transformers, or is it near-mandatory to run it NOS?
I am (still!) feel dissonance when someone joint Sigma-Delta DAC and NOS word close together. NOF should be OK abbreviation probably, but NOS???

Nevertheless... I can refer to the PCM1794 DAC (dddac) which works best in so-called NOS mode (even better from HQP filters btw but it is another story).

But again, anyway there is no relation between NOS/OS/DFs and my trafos, you should rely on to your own prefferences, my trafos are are suitable with any mode.
3. Application is a 3way active project i.e. six total channels. This disallows using the JFET buffers because clean enough separate power supplies are too complex. However, passive implementations have shown that the bass usually suffers the most. Would it be an agreeable assumption/compromise to use active on the bass and passive for mid & tweeter?
As I said, trafos for 449x are 1:1, so the output impedance from your DACs will not be changed and it is low enough as I understand for most of systems (600R-1k if I'm not wrong). In this regards you simply should be sure that your LF responce is OK within your system even without trafos, and then simply use my D60 trafos, they will not downgrade your LF response. Actually the LF will be even better with my trafos due to its overall SQ superioty against the OPs.


Thanks.
Ivan.
 
Good morning.
Some years ago I ordered the IV board for Ian's 90x8Q2M dacs (bisesik 2019v3). Still working fine. My questions:

  • What is the best I/V resistor value? There are some stock Dale's 4k12 in now on the secondairy site.
  • Can I use these trafo's for my other Ryan D3 TDA1541 DAC and 4 deck DDDAC?

Thanks in advance.
 

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Sure you can use trafos with D3 or DDDAC.
I think that Current source dacs PCM1794 in D3AC is diferent from other Io dac sources?
There are -6.2mA of DC component x 4 times, creating offset at the Riv @ direct output?
.
btw
is there on the topic some PDF about main chrs of transformers?
Primary inductance (open sec. and closed secondary)
Primary Rdc
Secondary inductance
Secondary Rdc
Capacitances
etc...
.
Thanks :)
 
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