Finally, we come to the day to have a listening test of this project. The comparison has been done with original Lundahl LL1673 (same Choke). Mine is potted, the other one is used as-is.
The system used is MP50Di power amplifier (a MOSFET amplifier). Originally, the preamp is Aikido based with 6AS7 and 6SN7 (correct me on this), but during this test, the tubes are changed with something new (compatible) which I can’t recall. This is a heavy 2-boxes preamp with marble enclosure. A big pain to move them from one place to another. So a big thanks to my friend DY who brings this today 😉
Another close up shoot of the main unit. The capacitors sealed in plastic. They are Jensen and Mundorf.
The back of the power supply box. We can see several chokes and high end parts inside. The main objective today is the Lundahl LL1673 hanging on one side of the box.
The original Lundahl deactivated for some time, then some jumpers are connecting the circuit to the potted version outside the box.
First we listen the original Lundahl, then we switch with the potted version, then return back again to the original Lundahl (well, we have to return the circuit to the original one which belongs to the owner of this preamp anyway).
The result is quite impressive. The potted version brings a significant improvement on the high extension. We can hear more details and resolution. The 3rd test which returns back to the original version of Lundahl also confirms the different. The high seems got more harmonic (crispier treble, sparkling high, more creamy, etc – I think that could describe what we hear). The different even could be heard from first few seconds.
Mid and low, probably not much different at this stage – or we are not paying extra attention on that part.
To be honest, I don’t expect such significant differences. We use Norah Jones, which the record is ‘just nice’, not a superb one. But definitely we can hear the lips detail more than what we used to hear with the original Lundahl – and that makes a significant different.
What I can’t say at this moment (and need more verification) is whether the potted version brings extra roughness/fatigue or not. I’m not familiar with the system, as I’m also not prepared to hear significant different. But definitely at this point, the original and potted one does sound different. An even more serious session could be very usefull.
It’s gonna be interesting to see how this will compare with other potted Choke like Tamura, Tango, or Hashimoto. It might not be an Apple-to-Apple comparison due to different inductance and resistance, but still gonna be an interesting finding. Will see.