Below are some examples of the measurements taken from the experiment explained in the previous post.

Frequency Response


This first figure (above) shows the stereo frequency response of the Steelhead for its MC input (and 400 ohms), with input values of .1, .4 and .6 mV. There is an interesting upwards curve starting at ~4kHz.


In comparison, here (above) is the frequency response of the XONO (@ 475 ohms). The curve exhibited by the Steelhead (although small) is not present here.

2. Phase Response:


Above is the phase response for the Steelhead. Phase response is most basically the ratio of the phase output to the phase input.


For comparison, here is the phase response of the XONO.


3. Idle Channel Noise:

Above is Idle Channel Noise for the Steelhead.


Above is idle channel noise for the XONO. The Steelhead has almost a 10-20 dB lower noise floor than the XONO for much of the auditory spectrum. Also interesting is that this how much louder this is than the idle channel noise for the MM cartridge (see below).

4. Intermodulation Distortion (w/ 2 frequencies: 19 kHz and 20 kHz [both at 0.6mV])

Above is the IMD for the Steelhead.


Notice the peak at 1KHz that is above the otherwise similar noise floor to the idle channel noise above. There are also some interesting things going on at 8 and 16 kHz. Not sure what that is, as it appears in the other measurements of the XONO (such as the idle channel noise for the MM cartridge [see below...]). The 1 kHz tone is caused by non-linearities in the device that cause the input signal to create beat frequencies (largest of which is the often the difference of the 2 signals).


5. Crosstalk vs. Frequency

Here is crosstalk vs. frequency. It is performed by measuring the signal in the an idle channel when sending signal through the opposite channel. Seems strange that we're seeing a few of those bumps, but those were present in both the Steelhead and XONO as is seen below.


The crosstalk for each of these is pretty good. Each line in the above graph is a channel trace of the amount of signal in the empty channel from the one that has signal. The low values of the red curve, and perhaps also the higher values of the blue curve at LOW frequencies could be the result of timeouts that occured during testing. As a sidenote, a timeout occurs with the AP as it records several values, and uses a settling algorithm to provide a final value for the measurement being taken. If the results are too varied, it has difficulty producing the settled value and instead provides an average of the last six values. The low frequency values were marked with the timeout symbol "T" when conducting this test.

Also of note, crosstalk is frequency-dependent: there is a +6dB increase in crosstalk for frequency octave.


Below are selected results for the moving magnet level inputs. Both units were set to 100 pF. The XONO was set to 47 ohms and the Steelhead was set to 50 ohms.

1. Frequency Response


That's a big jump! The above frequency response for the Steelhead demonstrates the output for swept frequencies at input voltages of 5, 7, and 10 mVrms.

The gain increase of the XONO was not as significant. However, the XONO also has a 10dB boost setting which was not tested. Also of interest is the intervals between the 3 input signals tested. Seems like quite a difference between 7 and 10 mVrms for the XONO, but less so for the Steelhead. Its the other interval (5-7 mVrms) that seems to be significant for the Steelhead.

2. Phase Response


The Steelhead MM phase response.


The XONO MM phase response is very similar to its MC response.

3. Idle Channel Noise

The above figure is the Steelhead idle channel noise. Strange peak at 16 kHz.


Notice how the noise floor of the MM setting is lower than the above MC setting. Also notice the peaks at 8 and 16 kHz. Strange.

4. Intermodulation Distortion (IMD)



This is the IMD for the Steelhead. The 1 kHz frequency peak is pretty substantial. The input for the IMD test was again 19 and 20 kHz test tones.
No difference beat frequency (1kHz) for the XONO. Instead take a look at that regime of beat frequencies surrounding the two main peaks. This is because the two frequencies interact not just as the difference, but frequencies f1 and f2 produce new frequencies at (and not limited to) f3 = f1 + f2, f4 = f1 - 2f1, and f5 = f1 + 2f2.

5. Crosstalk vs. Frequency

This is the crosstalk for the Steelhead MM. Looks pretty good at -80 dB, 20-20kHz.

Crosstalk for the XONO seemed better than the Steelhead. Again, as with the MC XONO settings above, this test was plauged by AP2700 timeouts at low frequencies; possibly affecting the difference in channels.

more to come: THD+N vs. Frequency and THD+N vs. Amplitude.