Good Point, but there is more benefit behind using a tranny…
It is not cancelling some of the harmonics, but all odd ones. As the d2 is the highest any way this is a major step.
secondly - and I thing imho the most important - it is not just a balanced output: there are REALLY two DACs inside the chip - One dac feeding the POS output and the other dac the NEG output.
so you ARE doubling the number of DACs - this is exactly the same as adding boards… Meaning a 4 deck DDDAC with a transformer is like a 8 Deck DDDAC with single ended output….
Also the low output impedance at low frequencies does a lot of good- I get a lot of feedback on the bass improvements using the Sowters. With a couple capacitor your out impedance is significantly higher at lower frequencies
example 1uF couple C has aprox 1k5 output imepdance at 100Hz - that is 20 times higher than with a transformer. at 20Hz it is ~ 8kOhm...
Another benefit is the galvanic isolation. Also, a transformer is a much more ideal balanced source than the average balanced tube or solid state buffer. It also acts as a LPF, generally with a well damped 2 pole roll off that is very benign in terms of phase shift within the audio band. Transformers are a sort of magic when used properly. The key is to get the correct transformer for the job.
Just a note about DC offset between the + and - dac outputs. This is a concern for some transformers IMO. Small input transformers can be saturated by even a tiny amount of DC current. If you look at the various Sowter data sheets you will see a warning in some of them about avoiding DC. There is no spec given for minimum DC current flow. Without actually checking with the manufacturer we do not know how much DC will be acceptable. My guess is that in some instances the answer is 0.
Having a correctly spec’d and implemented output transformer in your DAC will make it a much more universal component. It will be at it’s best with anything you put in front of it.
Thanks for adding this. All very true ! You are right on the right transformer for the job, hence I worked with Brian Sowter to get the special dddac version....
And dc offset was one important point here among other more audiophile aspects
here are two pictures - It is the green PCB. The Arduino board is piggy backed on it, but it is at the other side of the pcb, so you cannot see it here
Hey Doede
Do you sell the green board or as a kit?
Thanks
Simon
Hi Simon, no kits or official sales - I do have one extra PCB (I had made two...) I can sell this to you. It is all well documented so should be no big issue for you.
send me a mail to my normal email address please
I might also have some extra boards for my version with 27 switch positions that works with the standard Sowter 9335. Alternatively, you could just use a good old 27 position switch as recommended by Sowter instead of a PCB with an arduino and a bunch of relays.
Recently I added the 5v regulater on the mainboard dddac smooth dancer recomanded. It took me a few weeks to be delivered home. I must admit that this regulater is a clearly noticible upgrade in my system: nas - rpi2b+/moode, allo isolator, digi+ pro, 4-deck dddac, 15B/15B transformer - tubeamp.
Yes it’s a nice upgrade for small money.
I have to tell you about another upgrade in my setup. A while ago I bought the Sowter trafo’s from doede, but it seems that the cinemags was a better match against the Hegel preamp I had that time. I sold the Hegel and bought a SPEC preamp.
In the mean time, a friend of mine which had bought the Sowter’s I had earlier, also sold his Hegel preamp and is now playing on Einstein «the tube» preamp. Einstein is a very good sounding amp, but the Sowter’s was not a good match. The gain structure ended up wrong, and out went the Sowter’s and in with Cinemag 15b. Since the cinemags was mine I tried out the Sowter’s in my setup.
Holy cow....this was something else than earlier when I had the Hegel preamp. Sowter and SPEC is a very good match. Everything is improved, and it just tells me, as many times before, that matcing is important.
I have to tell you about another upgrade in my setup. A while ago I bought the Sowter trafo’s from doede, but it seems that the cinemags was a better match against the Hegel preamp I had that time. I sold the Hegel and bought a SPEC preamp.
In the mean time, a friend of mine which had bought the Sowter’s I had earlier, also sold his Hegel preamp and is now playing on Einstein «the tube» preamp. Einstein is a very good sounding amp, but the Sowter’s was not a good match. The gain structure ended up wrong, and out went the Sowter’s and in with Cinemag 15b. Since the cinemags was mine I tried out the Sowter’s in my setup.
Holy cow....this was something else than earlier when I had the Hegel preamp. Sowter and SPEC is a very good match. Everything is improved, and it just tells me, as many times before, that matcing is important.
Hey thanks for that post. Which Spec pre are you using? Is there a specific model? How much does it go for?
I am currently using the Cinemag 15/15B and was also contemplating the Sowter upgrade. However, reading that your friend's tube preamp did not match well with the Sowters is a bummer as I am also using a tube preamp.
Maybe you or Doede can explain why would Sowters not match well with a tube preamp, if that is actually the case? Also, my preamp is based on the 4P1L tubes and is a DHT amp. Any suggestions on whether this might be a good match.
Additionally, I have also put in the two 5V regulators that you had recommended. I must say there is a refinement that comes in with these regulators over the standard ones that I was using earlier. I have realised one thing that my aural memory is not that strong. I forget easily how any component sounded previously, after I live with an upgrade for a few days/weeks. As in, now it is hard for me to imagine how the DAC was sounding before these regulators were put in or how it sounded before I had put in the Cinemags. For me, the sound that i get now is the standard sound.
well…. I would be carefull to read "Tube amp" as in every tube amp ;-)
I am using Tube amps as well (DIY) and the Sowters match wonderfully….
Tube amp or not, matching is the key.
With Sowter on my friend’s Einstein, it was impossible to play louder than 9’0 clock on the volume control. Listening on low level was not an option.
Since my friend like the Sowter more than Cinemag, he send mail to Brian Sowter and he will make a trafo 1:1 and not 1:2, as doede’s custom Sowter’s.
I think this will do the trick on Einstein.
With Sowter on my friend’s Einstein, it was impossible to play louder than 9’0 clock on the volume control. Listening on low level was not an option.
Since my friend like the Sowter more than Cinemag, he send mail to Brian Sowter and he will make a trafo 1:1 and not 1:2, as doede’s custom Sowter’s.
I think this will do the trick on Einstein.
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If you advise which parameter or specification would you like to know to be able to comment about the matching, if such a thing is possible, I can fetch that information for you!!
Why dont you use your Sowter wired backwards?
Gesendet von meinem SM-G970F mit Hilfe von TrendStation
could you link to exactly the regulator you used? that would be helpful for all tweaker
It is about this regulator on the blue mainbord: LT3045-78XX Ultra Low Noise LDO Voltage Regulator
By the way I do not use the usb waveboard anymore.
pz1
The double smaller output voltage is only 6dB less, now the maximum volume will be just a little further on the potentiometer scale. It looks like this preamplifier has too much gain. Try the output through the capacitor without the transformer and see how the potentiometer goes. In principle with this DAC (and many others) for most power amplifiers we do not need a preamplifier, just a buffer with a unity gain or a passive - potentiometer. I use the Aikido cathode follower with the E88CC because it sounds better to me than passive one.
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