Monday, August 8, 2011


Scientific Conversions SC944-05

SC944-05LF Top View

SC944-05LF Bottom View

SC944-05 is a handcrafted transformer made by Scientific Conversions. The suffix LF stands for Lead Free.

SC944-05 Waveform

SC944-05 @ 200mv/100ns Div

SC944-05 @ 200mv/50ns Div

SC944-05 @ 200mv/25ns Div

Since the Vpp of the original waveform is around 3.3V, with PE65612 (1:1), I have to use resistors to decrease the output voltage level to 600mV. In the test above, those resistors were not removed, I think that's why the peak will be lower than the second one. If the listening experience is better than PE65612, I'll remove those resistors since they are no longer required due to SC944-05's primary/secondary ratio - 2:1.

PE65612 Waveform

PE65612 @ 200mV 25ns

Obviously, SC944-05 has less noise than PE65612 with nearly the same rise time. However, the jitter is not something we can see directly from the oscilloscope, but I believe that my ears will tell.

Listening and Conclusion

The listening experience of the SC944-05 is all positive, better resolution, more clear and accurate bass and the harmonics compare to PE65612.

I'm pretty sure that I'l never go back to PE65612 definitely!

Note for Usage

The pinout for SC944-05 is almost the same with PE65612, you can replace Pe65612 with SC944-05 directly except for SC944-05 needs an additional hole for its pin 2.

The pin 2 is for "shielding", which connects to the shield between the primary and secondary coils.
Th shielding will greatly improve the noise suppression, hence, except for creating an additional hole for SC944-05 while replacing the PE65612, remember to connect the pin 2 of the SC944-05 to the ground of the primary on transmitter side, and to the secondary ground if used on the digital receiver side.


After 3 hours running-in, I got new conclusion:

PE 65612 is NOT comparable to SC944-05, they are not at the same level!

Friday, August 5, 2011

PE65612 vs. S22083/S22160

Newava S22083 / S22160

I did a simple comparison on my current transportation system for Pulse Engineering Pe65612 and Newava S22083 / S22160. Here's the result.


Newava S22083

Newava S22160

Pulse Engineering PE65612


ON MY SYSTEM, both Newava S22083 and S22160 sounds worse than PE65612 which matched the waveform result. Not only less resolution but also more noise introduced.

Additional Informration

Thanks to Dr. Jon Paul, who gave me some hints and recommendation with similar results.
See Dr. Jon Paul's AES 2003 paper here.

Wednesday, August 3, 2011

Delta vs. Samsung

Apple Airport Express 802.11n

Open the AAE, you may find that, even with the same AAE model, the factory AAE equipped with different switching power supply modules.

I found that there are at least two switching power supply models.

DELTA Module

Samsung Module

Delta vs. Samsung

Delta @ 2.5 ms

Samsung @ 2.5 ms

Delta @ 1ms

Samsung @ 1ms

The listening experience is the same as the waveform, AAE with Delta module sounds better than Samsung module. This implies that different AAEs (with the same model, 802.11n) may sound different even without modification.

Monday, August 1, 2011

PO74G38072 and DSIX

The Unsolved Misery

Why the PO74G38072 sounds worse than the DISX with TC74VHCU04/PO74G04 ?

This is the question comes up on my mind after replacing the TC74VHCU04 with PO74G04.

My Own Explanation

Well, I'm just guessing, and I could be wrong, so if you think that I'm saying something stupid, share your comment please, will greatly appreciate for that.

Since in the design of DSIX, the output of the 74HC04 buffer is a combination of 5 sets of inverter. While using PO74G38072 on the DSIX, since the pinout is different from 74HC04 chip, I need to modify the connection. In the end, only one of two PO74G38072 buffer outputs is used. 

Take a look at the oscilloscope graph of PO74G38072.

We can see that the overshoot is very weak, actually we should call it "undershoot".
This is where I suspect the jitter coming from.

So why TC74VHCU04/PO74G04 sounds better?
Let's look at the following graph of the TC74VHCU04.

You'll see that in the waveform above, it might be easier for the DAC to tell if it is a rise or fall, so less chance for the DAc to miss interpret the signal. In other words, less jitter. Pay attention to the waveform, the overshoot is obvious.

Ok, now let's take a look at the DSIX design.

Why Mr. Shibasaki uses all the rest 5 sets of the 74HC04 output for the signal?

I guess he wants to create some reasonable "overshoot", since using only one set of the output will become "undershoot" in the end. By combining all the rest 5 sets, the signal level will be strong enough and the reasonable overshoot will be created.

Basically, this is why TC74VHCU04 sounds better than PO74G38072, however worse than PO74G04A.


I think both PO74G38072 and PO74G04 will have better result than TC74VHCU04, however please note that:

1. Do NOT use the PO74G38072 directly on the DSIX, the signal strength is too weak to create overshoot, jitter will be introduced in the end. With DSIX, use PO74G04 instead.

2. If you prefer to use PO74G38072, the circuit must be redesigned for sure.

DSIX with PO74G04


PO74G04 is an alternative ultra high speed solution for 74HC04, the specification is excellent, supports up to 1.125 GHz bandwidth and the propagation delay is less than 1.4 ns with rise/fall time 0.8 ns.

To me, this is an awesome solution as a replacement for TC74VHCU04.

PO74G04 On the Oscilloscope

PO74G04 @ 100ns/100mV

PO74G04 @ 25ns/100mV

Amazing rise/fall time (compare to the TC74VHCU04 in the following graph).

TC74VHCU04 @ 25ns/200mV

The overshoot and the ringing might be the noise from my power supply, will try to improve this later.

Listening Experience

Noticeable improvement discovered.

1. More silent background, this implies the resolution is greatly improved.
2. More solid bass, even when the bass guitar and the bass drum are played at the same time, you will be able to recognize them respectively.


Highly recommended, what are you waiting for?