專業級吉他無線系統 | NUX B-8

 專業級吉他無線系統 | NUX B-8

NUX brand already announced B-2 guitar wireless in 2017, and now they have several wireless products in this category.

NUX品牌從2017發布B-2吉他無線系統，至今有許多無線產品。

Recently NUX announced B-8, the ID design is quite unique, looks quite professional, and offers some interesting functions.

最近NUX發表了B-8，外觀工業設計相當獨特，看起相當專業且提供了一些有趣的功能。

B-8 comes with a bodypack TX, and pedal RX. Let's check the TX first.

B-8帶有腰掛式TX（發射端），以及效果器踏板型RX（接收端）。 讓我們先來看下TX的部分。

You can clip the TX on the guitar strap, and connect the additional cable to the guitar output jack.

TX可以讓你夾在吉他背帶上，並使用原廠附的導線接到吉他輸出接口上。

Most professional-stage wireless systems use the same design~ additional cable. Cause the stage wireless requires a long transmission distance, it means the TX has to run a higher RF signal. In this situation, the compact wireless design like B-5RC (directly into the guitar jack) will have RF high-frequency noise issues with active pickups or preamps. 

So the TX uses the additional cable can keep enough distance from pickups/preamps to avoid the RF noise issue.

多數專業舞台型無線系統都採用相同的設計～ 外接導線。 因為舞台型的無線系統要求遠距離的傳輸，也就意味著TX要執行高功率發射信號。 在這個狀況下，緊湊型的無線系統（如同B-5RC那種直接接到吉他輸出接口設計），會容易產生RF高頻噪聲（使用主動式拾音器或者帶有前級線路的吉他及貝斯。）

所以TX利用附帶的導線可以保持與 主動式拾音器/前級 足夠的距離避免RF射頻噪聲。

The TX has a built-in Li-battery, it can run 6.5 hrs while full-charged. While you take it off the strap, you can put it on the RX to charge. 

During the operation, you can even connect the power bank to the USB-C port to charge.

發射端內建鋰電池，充滿電後可連續使用6.5小時。 當你將TX從背帶拿下時，你可以將觸點面蓋上RX進行充電。

在TX工作中，你甚至可以外接『行動電源』接到TX的USB-C口進行充電。

TX's power button also offers the mute function, hold it for a while it will mute, and then you can change the guitar. Short press again, and it will start to work again. Long press to turn ON/OFF.

發射端的『電源按鍵』同時提供了『靜音』功能，按住他一下子，就會進入『靜音』狀態，此時你就可以更換吉他使用。 再次短按，就開始工作。 長按此案件就可以進行『開機/關機』。

The TX offers a unique "CABLE TONE" function, if you engage it, the built-in RC circuit can adapt to the pickup's impedance to simulate the "real cable capacitor effect". It sounds pretty natural. 

Note: If you use active pickups, the cable tone won't be obvious due to the low impedance. 

發射端提供了很獨特的『CABLE TONE』功能，如果你開啟他，內建的RC電路可以適配吉他的拾音器阻抗來模擬『真實的導線電容效應』。 聽感上相當自然。

註記： 如果你使用的是主動式拾音器，由於低阻抗的原因，導線模擬聽起來會不明顯。

Let's check the RX. The RX can be powered by "7V to 12V DC, 500mA min, negative tip power supplies(Receiver)", I think most guitarists will feed 9V negative tip power. 

讓我們來看下RX，RX可以使用7V~12V DC 外正內負 直流電500mA9來供電，我想多數吉他手都會使用9V 外正內負來供電。

So I checked the power consumption with 2 situations: 

TX & RX work with the wireless operation. 

TX puts on RX for charging. （The power consumption of charging is various, it depends on TX's battery status. Here I guess at least 320mA is required.)

所以我量測了兩種耗電量場景： 

TX及RX進行無線工作。

TX放在RX上進行充電。 (充電時的耗電量是變動的，他會依據TX電池電量狀態變化。 這裡我猜測320mA耗電是需要的。）

For the RX, the special part is the routing system design. It offers SEND/RETURN to let you connect the pedals from the beginning to the end and back to the RX to use RETURN OUTPUT to connect with the amplifier. The RX even offers XLR balanced out to the PA system.

接收端特別的部分為『Routing System』設計。 RX提供了 SEND/RETURN 讓你可以連接效果器的起點到信號終點回到RX本體，利用RX的『RETURN OUTPUT』來連接音箱擴音。 接收端還有提供XLR的DI OUT平衡輸出，讓你接到PA系統。

The RX can be a pedal tuner or a volume boost!! You can set up the function and footswitch on the RX.

接收端還可以作為『踏板調音器』或者『音量推子』！！ 你可以在RX本體上設置這些以及踩釘功能。

Performance Testing and Comparison | 性能測試與對比

System Latency | 系統延遲

The working principle of B-8: 2 frequency points for wireless transmission with 1 MHz bandwidth. The lowest latency 2.5ms sends the transmission signal 2 times. The longest latency 8.7ms sends the transmission signal 12 times.

B-8工作原理： 使用2個頻點來做無線傳輸，使用1 MHz帶寬工作。 最低延遲為2.5ms，一共發射兩次。 最長延遲為8.7ms，一共發射12次。

Shure GLXD6 working principle:  

Group 1 with 4.0ms latency.

Group 2&3 with 7.3ms latency.

Group 4 with 7.3ms latency.

Note: Shure GLXD6 uses 2 MHz bandwidth.

Shure GLXD6工作原理： 

Group 1 時， 4.0ms 系統延遲。

Group 2&3時， 7.3ms 系統延遲。

Group 4時， 7.3ms 系統延遲。

註記: Shure GLXD6採用 2 MHz帶寬。

According to B-8's 1 MHz bandwidth, for real environment testing, B-8 can run longer distances without RF interference than Shure GLXD6.

實測真實環境中，由於B-8使用 1 MHz 帶寬工作，B-8可以移動得更遠且不受RF射頻干擾。

Note: 2.4GHz wireless is a kind of WAVE. According to what we learned before: v = f λ , λ is the wavelength.

Bandwidth is related to the wavelength, and in digital communication systems, it also means the data size.

註記： 2.4 GHz 無線也是一種波。 根據以前所學： v = f λ ， λ 為波長。

帶寬與波長相關，在數位通信系統裡，帶寬也意味著數據封包大小。

Note: Why is the bandwidth smaller can against interference better? You can think 4MHz is like a truck, 2MHz is like a car, 1MHz is like a motorcycle. While they run on the road, the motorcycle can avoid others easily.

Small is always better? It's also related to the compression algorithm, how to keep the unzipped sound high quality is the challenge. For example, Xvive U2 uses 4MHz, so it drops the signal more easily than others. Shure GLXD6 uses 2MHz, it's much more stable than most competitors, and their compression algorithm also keeps the unzipped sound with good quality. NUX B-8 uses 1MHz and also keeps the unzipped sound great quality. It means B-8's compression algorithm is the most premium.

註記： 為什麼帶寬越小、抗干擾能力越強？ 你可以將4MHz帶寬想像成一台卡車、2MHz帶寬想像成一台轎車、1MHz帶寬想像成一台摩托車。 當他們在路上跑時，摩托車能輕鬆躲避其他人。

帶寬小永遠是最好的嗎？ 這跟『壓縮算法』息息相關，如何保持解壓縮後音質依然高保真是最大挑戰。 舉例來說，Xvive U2採用4MHz帶寬，所以他相較其他競品就容易掉信號。 Shure GLXD6採用2MHz，傳輸上相對穩定，且Shure的壓縮算法依然保持解壓縮後的高保真音質。 NUX B-8最屌的就是能將信號壓縮到 1MHz 且解壓縮後音質依然高保真，這就是最困難之處。

Dynamic Range | 動態範圍

NUX B-8 dynamic range: 124 dB

Shure GLXD6 dynamic range: 120 dB

Note: Boss WL series' dynamic range is 110 dB.

註記：Boss WL全系列的動態範圍都是110dB，Line 6由於採樣率不到44.1KHz基本上不用比了，Xvive大約在105dB。 

System Noise | 系統底噪

Using 1K frequency to test the system noise, Shure GLXD6's system noise is around -140 dB, and NUX B-8's system noise is around -150 dB.

Note: A great audio system can accept the system noise under -120 dB. (around 10uV) The guitar amplifier's system noise is much louder than the 2 wireless systems.

上圖可以看出採用1K頻率去測試系統噪聲時，Shure GLXD6的底噪約在-140 dB左右，而NUX B-8底噪約在-150 dB左右。

註：一般來說，優秀的音頻設備底噪在-120dB以內都屬於可接受。（大概是10uV) 而像吉他音箱的白噪聲基本都遠大於上述產品。

Frequency Response | 頻率響應

Shure enhanced the signal a little bit. NUX B-8 is more flat.

Shure的信號有些微放大。 B-8頻響更為平坦。

Frequency vs Distortion | 頻率對應失真特性

Shure has more distortion according to the whole frequency.

But these 2 systems' distortions are quite small already.

Shure明顯在各個頻率都比B-8容易失真。

但這兩個系統的失真都處於極小的狀態了。

Headroom ｜ 動態餘量

Shure GLXD6's headroom is wider than NUX B-8.

Shure GLXD6 的動態餘量比NUX B-8還寬一點。

Note: Headroom means the acceptable signal range till overdrive. You can check the above, B-8 runs over 1 at around 2.034 Vrms, and GLXD6 runs over 1 at around 2.7 Vrms.

註記： Headroom（動態餘量）代表著距離『過載』或『失真』的可承受信號範圍。 從上圖你可以看出B-8在跑出縱軸1時，約在2.034 Vrms，而GLXD6跑出縱軸1時，約在2.7 Vrms。

B-8:

2.034 Vrms x ±(√2)＝ ± 2.8775 V ，基本上吉他跟貝斯都可以使用B-8，但主動式貝斯就要注意不要將所有信號開到最大來使用。 (主動式貝斯信號範圍約 ± 3V)

註：被動式吉他信號範圍約 ± 1V

      主動式吉他信號範圍約 ± 2V

      主動式貝斯信號範圍約 ± 3V

Let's talk about 2.4GHz | 淺談2.4GHz

Nowadays, there are many 5.8GHz wireless products, even Shure GLXD6 update to GLXD6+ to run both 2.4GHz & 5.8GHz. Why did NUX B-8 choose 2.4GHz?

There are 2 main reasons:

1. 5.8GHz is not allowed in Japan.

2. If you can make 2.4GHz stable and reliable with auto-hopping technology. 2.4GHz has better diffraction than 5.8GHz. It will be more suitable for outdoor application, especially on the stage.

如今有許多的5.8GHz無線產品，即使Shure GLXD6也停產更新替代為GLXD6+，並採用2.4GHz及5.8GHz雙系統。 為什麼NUX B-8採用2.4GHz？

主要有兩個因素：

1. 日本不能使用 5.8GHz。

2. 如果你能夠實現2.4GHz 『工作中自動跳頻』技術穩定且可靠。 2.4GHz 擁有比 5.8GHz 更好的繞射穿牆性。 這會更適合戶外的使用場景，特別是在舞台上。

2.4GHz is a general name, actually, it works from 2.4GHz to 2.483GHz.

2.4GHz是個通稱，實際上為2.4GHz~2.483GHz之間。（請見維基百科）

Shure slashes 2.4GHz as 19 frequency bands. Taking off 3 strong WiFi interference bands and the auto scan & sync band, there are 15 bands for wireless transmission.

Shure將2.4GHz頻段切割成19個頻段，避開WiFi設備干擾很強的3個頻段以及對碼使用的1個頻段後，挑選出15個頻段來工作。

（專業級2.4GHz私有協議帶寬通常為2MHz（數位壓縮差的會使用到4MHz帶寬），加上Ramp Up / Down的 1 MHz，需要4MHz的頻寬。）

（83-8）/ 4 = 19個頻段 (最前面的4MHz跟最後面的4MHz皆須捨棄）

The bandwidth is related to frequency band slash and packet size. According to the above, you can realize Shure's compression algorithm is quite professional already. It compresses the packet small enough. (2MHz) The most difficult part of wireless is: How to compress the packet small enough and unzip it to keep high-quality sound without distortion.

至於頻段切割與封包大小跟帶寬有相當的關係。 由上可知道Shure的數位壓縮算法相當厲害，可以將封包處理的很小。(2MHz) 而樂器的無線傳輸最難的就在於如何壓縮算法將封包壓縮得夠小且保持高保真的音色還原。

So NUX B-8 can run 1MHz bandwidth and unzip the sound keeping high quality. The compression algorithm is better than Shure.

Note: 1MHz is thinner than 2MHz to avoid RF interference bands.

所以NUX B-8可以使用 1 MHz 帶寬且解壓縮後依然維持高保真的音頻。 其壓縮算法比Shure還要高竿！！

註記： 1 MHz 帶寬比 2 MHz 小，更容易抗干擾。 （你可以想像瘦子更容易避開路上行走的人們。）

Below is the working principle of Shure GLXD, I only type Mandarine to explain how it works.

而眼尖的朋友可能意識到Shure在Group1時，系統延遲最短，在4ms左右。但在其他Group時，系統延遲都來到了7.3ms。

在Group1的做法是，發射端一個通道一次採用6個頻率做發射（實際上只有3個頻率工作，例如2424與相鄰的2425實際上只有一個在發射，與此同時發射跟接收會去偵測當前工作環境評估是否自動跳頻切換避開干擾。），而接收端只要接收到3個頻率其中1個頻率的封包即可。 這時候接收端並不會回傳信號給發射端，所以只有一次的傳輸才能將延遲降到最低。 但由於沒有回傳確認機制，所以Shure一次採用6個頻率就是要利用工作中跳頻避免容易掉信號的考量。（發射頻率越多，掉包機率越低，反之發射頻率越少，掉包機率越高。）

而Group2的作法為3個頻率發射＋接收端通知發射端跳頻：

這個做法由於是經由接收端來告知發射端是否切換跳頻，所以系統延遲就來到7.3ms了。

但好處就是，漏封包的機率比Group1低。 所以也是延遲與漏包的平衡點抉擇。

Group3的做法為2個頻率發射＋接收端通知發射端跳頻：

例如Group3/Channel1採用了2415,2416,2443，實際上發射的為2415跟2416取其一，加上2443依序發射信號。 此時接收端只要接收到其一即可，若當前2415會掉封包的話，接收端就會通知發射端跳頻道2416來工作。

而Group3跟Group2最大的差別就是犧牲掉包的機率來滿足8組設備同時工作的可能性。

Group4的做法類似藍牙溝通協議，是採用循環發射的做法，這個做法的好處是掉包可能性最小，但缺點就是系統延遲很大。 而且如此一來就不可能與其他設備同時工作了。

所以Group 2,3,4就是在 『同時工作組數』與『掉包機率』做取捨了。

So the 2.4GHz wireless system is a balance of "Signal Strength", "Transmission Distance", "Pickup Noise", and also the balance of "Digital Compression Algorithm to minimize the Bandwidth", and "Unzip with High-quality Sound".

The most difficult part is "Digital Compression Algorithm to minimize the Bandwidth", and "Unzip with High-quality Sound". To achieve this target can be "professional wireless".

所以2.4GHz無線系統就是一種在『信號強弱』『傳輸距離』『拾音器噪聲』做平衡取捨，以及『數位壓縮算法降低帶寬』『維持高保真音質』做平衡取捨。

其中最難的就是『數位壓縮算法』這個環節，因為只有達到有效的壓縮封包並維持高保真音質的狀況下，這個產品才可以說得上『專業產品』。

So the NUX B-8 can run 1 MHz bandwidth with the shortest 2.5ms latency and bring back the unzipped sound with high quality. It also keeps stability with auto-hopping technology for long transmission distances. It may be the best 2.4GHz guitar wireless system in the market currently.

所以 NUX B-8 可以採用 1 MHz 帶寬，最短延遲僅2.5ms且解壓縮的音質依然高保真。 長距離傳輸中採用『工作中自動跳頻』技術保持穩定度。 它應該是目前市面上最棒的2.4GHz吉他無線系統了。

Tips for wireless system | 使用無線系統的技巧

There is an APP you can get to detect the current RF environment for 2.4GHz or 5.8GHz.

WiPry:

https://apps.apple.com/us/app/wipry/id442143525

https://play.google.com/store/apps/details?id=com.oscium.WiPry&hl=zh_TW

All the wireless systems will advise you to operate it far from the WiFi router at least 2 meters. Using the app can help you to detect the WiFi or RF interference source.

這邊你可以下載一個APP來幫助你偵測當前的RF環境，他可以偵測2.4GHz或5.8GHz。

WiPry:

https://apps.apple.com/us/app/wipry/id442143525

https://play.google.com/store/apps/details?id=com.oscium.WiPry&hl=zh_TW

所有的無線系統產品，都會建議你使用時距離WiFi router至少兩米遠。 使用這個APP可以幫你偵測WiFi或者RF干擾源。

The pedal receiver usually puts the antenna on the top, as you can see B-8 has 2 antennas to enhance the signal. One thing you have to notice, please put the RX as high as possible to let the antenna higher above than other pedals without metal shielding.

踏板型接收器通常會將『天線』放置在頂部，你可以看到B-8帶有兩個天線用來增強信號接收。 有件事你一定要注意，務必將RX放置的盡可能『高』，讓天線高於其他效果器的高度，避免金屬屏蔽遮擋住RX。

購買鏈結➫

https://www.monkcustom.com/ecommerce/nux/wireless/nux-b-8.html