Just an update on bypassing the opamp analog output stage and sending the signal to line transformers as posted.
Ended up using Altec 15356A's with the recommend filtering on the input and outputs.
Much thanks to Bill Fuss for all his help with this project; he as taken the time to post much of his findings, and also was nice enough to send me PM's with his recommendations on what filter values to use.
I have one of the early versions of this DAC, with the coax input transformer and without all those switches to change the sampling.
Have the transformers hooked up for only about 24 hours, but can say that it has much promise to be better than my tweaked out "small DAC" with Cinemag 15/15B transformers on the output.
IMO - the sound with the Altec transformers on my "big DAC" has more detail and transparancy, and should only get better with a few days burn in.
Cheers to all that have contributed to this thread.
Ended up using Altec 15356A's with the recommend filtering on the input and outputs.
Much thanks to Bill Fuss for all his help with this project; he as taken the time to post much of his findings, and also was nice enough to send me PM's with his recommendations on what filter values to use.
I have one of the early versions of this DAC, with the coax input transformer and without all those switches to change the sampling.
Have the transformers hooked up for only about 24 hours, but can say that it has much promise to be better than my tweaked out "small DAC" with Cinemag 15/15B transformers on the output.
IMO - the sound with the Altec transformers on my "big DAC" has more detail and transparancy, and should only get better with a few days burn in.
Cheers to all that have contributed to this thread.
I,m afraid they are not large enough. They will saturate at lower freq . You need +15dbm or around 100mw at 30hz capable.
Thanks a lot Bill,
I meanwhile found a provider for Neutrik NTL1 transformers which I understand are similar to the Studer used successfully by some experts here. Franz Gysi on first I think.
I remember a direct wiring from DAC chip and to outputs without any RC circuit. I'm going to check this on the thread.
I meanwhile found a provider for Neutrik NTL1 transformers which I understand are similar to the Studer used successfully by some experts here. Franz Gysi on first I think.
I remember a direct wiring from DAC chip and to outputs without any RC circuit. I'm going to check this on the thread.
The 1798 is a current output chip, you will need step up trafos. They usually use 18-20/1 ratios.
Best, Bill
One can use also 1:1 trafo followed by for example tube stage with gain about 20x
The A20 can be set at 600 : 50 ratio max (12 gain)...will that be enough..? or must it be at 18 to 20 gain...?
can you kindly share some gain circuit McGyver?
I tried 1:10 trafo and it worked properly.
Yes, I can, but not now. So many work to do and the hours are not made of rubber.
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Thanks Bill,
I tried this out, but the 1 nF had no impact in the visible audioband.
I asked David Carter. He told me that the 1k resistors after the Dac were responsible for the early frequency roll off.
He was right. I removed them and now I have a perfect frequency response!
The sound is extremely good, much better than before, but I do get a very hot signal now.
Maybe I should try the windings in paralell instead of in series...
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Hello folks, I received this Dac a couple of days ago and I am listening to it.. I am just listening to 44.1 material from my PC and being that this is the first Dac I buy Ever.. I had no idea what I was missing, but I knew I had to buy a DAC to see what's all the fuss about... and my question is what's wrong with the stock sound? to my untrained/novice ears it sounds great.. the separation of instruments is well, surprising to me, I hear everything more clearly, the bass has more slam and more defined, the whole presentation appears faster to me and my little 2-ways DIY speakers never sounded better before.
I like it a lot and I hope to refine it as all of you are doing as time goes by and I can't wait to hear what it sounds with the correct trainies.
But mainly I want to thank you All here for contributing to this hobby and sharing information to make our life more pleasant..
Cheers..
I like it a lot and I hope to refine it as all of you are doing as time goes by and I can't wait to hear what it sounds with the correct trainies.
But mainly I want to thank you All here for contributing to this hobby and sharing information to make our life more pleasant..
Cheers..
The lundahls sound terrific.
All cd-players and DACs are crippled by the use of these run-of-the-mill opamp outputs. They measure fine and that is the reason why all thechnicians implement them, but they all exhibit that dull, grey sound for which people tend to blame digital sound. As soon as you hear a modern DAC thruogh these Lundahls, or through a simple active stage like the Passlabs D1 stage, you hear how lifelike and colourful digital sound can be!
I can very much recommend Kevin Carter from K and K audio K & K Audio - Lundahl Transformers, audio DIY kits and more as a good source for Lundahl. Kevin knows a lot about them, and he is a very friendly person. You can alwasy ask him for advice.
Cheers,
Lucas
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If you are using the LM4562, they really do respond well to a really clean, low impedance power supply. I use a LM4562 in my modified Silicon chip headphone amplifier (the metal can version HA - much better than the NA), which is fed from a JLH power supply ripple reducer (lowers PSU noise and impedance). Without this board, the LM4562 sounds relatively weak. Using the same boards on the 12V supply for this dac, with LM4562 fitted, had the same huge improvement.
More info in the SCHA section at Rock Grotto
More info in the SCHA section at Rock Grotto
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I have a couple of the Altecs as well.
Would you mind sharing the values you settled on for making the modification? If you could include a photo or two, that would be great.Thanks in advance,
Steve
Hey guys....
I am totally late to this thread, but I just got one of these- and hooked it up immediately after getting it.
I am currently building a Shigaclone transport- and have no other digital source but my laptop via USB.
My first impressions with this admittedly meager setup were not at all favorable.
After listening to multiple CD's that I am intamately familiar with- I was able to form a somewhat impromptu opinion:
It's just a flabby, "hollow" sound; almost like singers have their hands cupped over their mouths; the sound was gray and boring..
Time to start modding!!
I am totally late to this thread, but I just got one of these- and hooked it up immediately after getting it.
I am currently building a Shigaclone transport- and have no other digital source but my laptop via USB.
My first impressions with this admittedly meager setup were not at all favorable.
After listening to multiple CD's that I am intamately familiar with- I was able to form a somewhat impromptu opinion:
It's just a flabby, "hollow" sound; almost like singers have their hands cupped over their mouths; the sound was gray and boring..
Time to start modding!!