列印
上層分類: Digital audio source and Digital Signal Processing
點擊數: 5402

這個USB音效卡是跟Praxis Measurement System三個月前一起購入的,購入原因是Liberty Instrument網站推薦這張卡搭配筆電,看在M-Audio在專業領域的名氣,產品應該不會太差,雖然是七八年前的產品。以下是簡單心得:

 

 

優點:
1. 體積小
2. 有光纖輸出入

缺點:
1. 由於很老的產品,這張卡只支援USB 1.1,最大的不滿是雖然號稱96kHz/24bits,不過竟然是要在半雙工下才能達到96kHz,也就是說,只能在撥放和錄音中選一開啟,若是雙向同時開啟,則最高只能支持48kHz/24bits,雖說不影響音頻測量,總有上當的感覺。

2. 價格不具競爭力,以USD$100左右的價位,不如買Amazon正在跳樓拍賣,只要USD$89的EMU 0202。

3. 規格相對不佳,承上,EMU 0202可是號稱A/D D/A都有 SNR>112dB的實力,而且取樣率更是高至192 kHz,所有接頭鍍金,規格全面勝出。

當然啦,這些缺點是跟假想敵EMU 0202做比較,不然的話Transit已經ˋ是非常夠水準的音效卡了,尤其是他有S/PDIF輸出入。網路上有些人把這張卡當成PC音源輸出,只使用Line-out,操作在96kHz,不過它的THD不是太理想,也許可以透過電路修改來改善吧。

附上RMAA測試數據,測試條件:Line out->Line in loopback

 

RightMark Audio Analyzer test report

Testing device Transit USB Out 1/2
Sampling mode 24-bit, 48 kHz
Interface MME
Testing chain External loopback (line-out - line-in)
RMAA Version 6.2.3
20 Hz - 20 kHz filter ON
Normalize amplitude ON
Level change -0.1 dB / 0.0 dB
Mono mode OFF
Calibration singal, Hz 1000
Polarity correct/correct



Summary

Frequency response (from 40 Hz to 15 kHz), dB
+0.03, -0.01
Excellent
Noise level, dB (A)
-93.9
Very good
Dynamic range, dB (A)
93.8
Very good
THD, %
0.0010
Excellent
THD + Noise, dB (A)
-87.5
Good
IMD + Noise, %
0.0057
Excellent
Stereo crosstalk, dB
-94.0
Excellent
IMD at 10 kHz, %
0.0059
Excellent
General performance
Very good



Frequency response



From 20 Hz to 20 kHz, dB
-0.07, +0.04
From 40 Hz to 15 kHz, dB
-0.01, +0.03



Noise level



Left
Right
RMS power, dB
-92.7
-92.7
RMS power (A-weighted), dB
-93.9
-93.9
Peak level, dB FS
-77.3
-75.6
DC offset, %
-0.0
-0.0



Dynamic range



Left
Right
Dynamic range, dB
+92.7
+92.7
Dynamic range (A-weighted), dB
+93.9
+93.8
DC offset, %
-0.00
-0.00



THD + Noise (at -3 dB FS)

Spectrum graph

Left
Right
THD, %
+0.0010
+0.0010
THD + Noise, %
+0.0047
+0.0048
THD + Noise (A-weighted), %
+0.0042
+0.0042



Intermodulation distortion

Spectrum graph

Left
Right
IMD + Noise, %
+0.0057
+0.0058
IMD + Noise (A-weighted), %
+0.0050
+0.0050



Stereo crosstalk

Spectrum graph

Left
Right
Crosstalk at 100 Hz, dB
-92
-93
Crosstalk at 1000 Hz, dB
-93
-93
Crosstalk at 10000 Hz, dB
-81
-80



IMD (swept tones)

Spectrum graph

Left
Right
IMD + Noise at 5000 Hz,
0.0058
0.0059
IMD + Noise at 10000 Hz,
0.0058
0.0060
IMD + Noise at 15000 Hz,
0.0059
0.0058



Spectrum graph

Spectrum graph

Spectrum graph