Post by jh4db536 on Oct 13, 2021 10:21:13 GMT -5
The DIY Sangaku has been released recently, this time at a price that's reasonable. I've actually never heard an original retail product btw. I have my biases with regards to silicon and hybrid amps but this to me is an experiment more than anything.
TLDR: the nutube by itself IME is highly capable because i can make it sound the way i want. It ended up not working out as a preamp (tested with a Tandberg 3006 and Turntable vs Rockna preamp mode) just too much microphonics and not good pairing. I built this specifically around Senn HD580 and 600. Found it works for fostex TH909 too. Not good pair for HD800. It is the most Fun sounding Headphone Amp i've ever heard or built and i'm shocked it's coming from something like this.
Looks to be a 4 stage hybrid amp: Opamp input > NuTUbe > Jfet > Opamp output
i want to make it very clear that i am not impressed at all with the way this sounded when i finished building the way it was intended. I Do believe there is Potential for something good after this experience. The NuTube itself actually does sound Very good. The correlation is high with respect to the Nutube and overall amp sound; and therefore, it must respond very well to modifications. Aside from the specified range of B+ and filaments, it is highly sensitive to the same modifications you would do to a regular tube amp. In other words, this amp is extremely malleable for tuning and voicing without touching the solid state section.
I would say microdynamics and bass quality is its weakness relatively and i feel it's related to the solid state output stage not being able to keep up with sustained deep bass notes. Aggressive attack, strong macro dynamics and strong mids are its strengths. I find this to sound more traditional triode-like than my pure tube amp; if you're expecting something close to neutral this is not it. Has a very midforward presentation (i like but might not be everyone's jam). When i say Attack aggro and slam, the mainstreet level has Nothing on this.
With tweaks and tuning this amp can sound Muscular aF, tone saturated, lively, Phat, less dry, more euphonic, and really really Fun AggroFi without being so revealing and harsh with terrible recordings. That is not an excuse for poor performance. I think the bass is a little more flabby than a comparable AMB M3 with the default large value cathode cap installed in the Sangaku, but once you modify that the bass gets much tighter and acceptable. Everything else, the AMB M3/Rebel is blown away.
What surprised me most is how tubey this amp sounds for a hybrid with so much silicon in it ... that is the reverb (decay and sustain not as good as real 2a3), separation, layering, triode n shaped sound (mid forward AND rolled off fr at extremes; idc what squiggles it measures at 150ohms). Also, with all the opamps and Sand in the signal path, there doesn't appear to be obvious sins of Omission or bleached sound. It also might work well on non 300ohm headphones (i use senns), but that's usually where amps that sound like this fail.
The Korg stage appears to be built almost exactly to the datasheet suggestion. This stuff is still infant vanilla and there is still little creativity going on with it
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I hypothesize that given the Nutube is extremely low power (17mA filament and microamp anode), that having a basic LM317 and ~70v multiplier B+ PSU, it somehow performs very very well. My guess is it's behaving like a flea watt tube and soo efficient that the PSU doesnt matter. I am actually amazed that this is capable of such potential while having so many Features that a purist would consider blasphemy.
TLDR: the nutube by itself IME is highly capable because i can make it sound the way i want. It ended up not working out as a preamp (tested with a Tandberg 3006 and Turntable vs Rockna preamp mode) just too much microphonics and not good pairing. I built this specifically around Senn HD580 and 600. Found it works for fostex TH909 too. Not good pair for HD800. It is the most Fun sounding Headphone Amp i've ever heard or built and i'm shocked it's coming from something like this.
Looks to be a 4 stage hybrid amp: Opamp input > NuTUbe > Jfet > Opamp output
i want to make it very clear that i am not impressed at all with the way this sounded when i finished building the way it was intended. I Do believe there is Potential for something good after this experience. The NuTube itself actually does sound Very good. The correlation is high with respect to the Nutube and overall amp sound; and therefore, it must respond very well to modifications. Aside from the specified range of B+ and filaments, it is highly sensitive to the same modifications you would do to a regular tube amp. In other words, this amp is extremely malleable for tuning and voicing without touching the solid state section.
I would say microdynamics and bass quality is its weakness relatively and i feel it's related to the solid state output stage not being able to keep up with sustained deep bass notes. Aggressive attack, strong macro dynamics and strong mids are its strengths. I find this to sound more traditional triode-like than my pure tube amp; if you're expecting something close to neutral this is not it. Has a very midforward presentation (i like but might not be everyone's jam). When i say Attack aggro and slam, the mainstreet level has Nothing on this.
With tweaks and tuning this amp can sound Muscular aF, tone saturated, lively, Phat, less dry, more euphonic, and really really Fun AggroFi without being so revealing and harsh with terrible recordings. That is not an excuse for poor performance. I think the bass is a little more flabby than a comparable AMB M3 with the default large value cathode cap installed in the Sangaku, but once you modify that the bass gets much tighter and acceptable. Everything else, the AMB M3/Rebel is blown away.
What surprised me most is how tubey this amp sounds for a hybrid with so much silicon in it ... that is the reverb (decay and sustain not as good as real 2a3), separation, layering, triode n shaped sound (mid forward AND rolled off fr at extremes; idc what squiggles it measures at 150ohms). Also, with all the opamps and Sand in the signal path, there doesn't appear to be obvious sins of Omission or bleached sound. It also might work well on non 300ohm headphones (i use senns), but that's usually where amps that sound like this fail.
The Korg stage appears to be built almost exactly to the datasheet suggestion. This stuff is still infant vanilla and there is still little creativity going on with it
.I hypothesize that given the Nutube is extremely low power (17mA filament and microamp anode), that having a basic LM317 and ~70v multiplier B+ PSU, it somehow performs very very well. My guess is it's behaving like a flea watt tube and soo efficient that the PSU doesnt matter. I am actually amazed that this is capable of such potential while having so many Features that a purist would consider blasphemy.
