Friday, May 1, 2020

The depth view of Boost pedals features NUX Boost Core Deluxe.

Blog Contribution: Monk Li (Taiwan) Marketing Director NUX | Cherub Technology.


The depth view of Boost pedals in my own words.


I still remember that more than 20 years ago, many guitarists would put more overdrive pedals in the pedalboard to boost the main drive sound. More than ten years ago, everyone's definition of Boost has become more clear, so there are more and more brands specializing in the development of Boost effects. As for so many types of Boost on the market, which one is right for you?

Today I will analyze Boost from a deeper perspective based on the circuit principle, which may be helpful for you who are thinking about how to choose Boost!

Before that, I would like to recommend you to read an article:


Okay, then let's cut into the topic I want to talk about today.
According to the circuit principle, we initially divided the following Boost lines:
1. Non-inverting OP-Amp
2. Inverting OP-Amp
3. MOS-FET
4. JFET
5. SRPP / Mu-amp FET
6. BJT
*Here I quote the video content of Brian Wampler | Boost Pedals

Non-inverting OP-Amp




















The most classic representative of OP-Amp type is the MXR Micro Amp, an extremely simple circuit with flat frequency response.












The overall frequency response is very flat, basically a faithful amplification without any rendering. As for whether it sounds good or not, then the judges should obey your ears to judge.


Inverting OP-Amp




For the Inverting OP-Amp type, the most classic representative is the RC Booster. Without EQ modification, the original circuit appears as the low frequency is slightly attenuated (this part may not be heard because of the lower than 80Hz in the guitar performance), and the intermediate frequency is slightly elevated.

















MOS-FET


















The MOS-FET type Boost classic representative is Z VEX's SUPER HARD ON, and the obvious feature is that there will be a lot of noise when rotating the potentiometer. (Crakie Okay)



From the frequency response analysis, the overall frequency response curve is also quite flat.

















JFET
























This category of Boost is often referred to as Preamp Pedals, perhaps because the microphone preamp usually uses JFET for amplification. The classic model in this category is the EP Boost.


When the JFET boost meets a powerful pickup or the pickup is too close to the strings, it will sound crappy.






SRPP / Mu-amp FET




From the frequency response, SRPP JFET boost is designed with obvious Low Cut.




















BJT

The most classic of BJT type is the early Rangemaster, which is the Top Boost type most often said. This kind of Boost is the easiest to squeeze full Gain.
















Let's feel the classic tone of early Brian May ~


From the frequency response, it is indeed Top Boost. Basically, the mid and low frequencies are cut wildly!















In fact, there is a special Boost method later, which is to use two FET single tubes to amplify the cascaded Boost. I personally like this type of Boost, but this is not the focus of our discussion today. I will find another opportunity to introduce this type of Boost in the future.




NUX Boost Core Deluxe























Based on the above, I believe everyone has a deeper understanding of Boost, but I also believe that many viewers have been dizzy. So next let's talk about the straight article with some goods.



NUX Boost Core Deluxe integrates two circuit forms of RC Booster and AC Booster, and adds a circuit similar to Treble Boost before these two Boost circuits, which can be amplified at full frequency when switched to Spark mode through a 3-way toggle switch in case of overdrive, increase the brightness of the sound.
















































The Clean mode (RC Boost) retains a very transparent Boost signal, just like the original RC, which is very suitable for pushing the first-stage tube of the vacuum tube amplifier. Use high and low bass EQ to tweak the sound of the tube amplifier.
Note: Maximum amplification 20dB





The Dirt mode (AC Boost) will increase more gains (asymmetric diodes cutoff to produce overdrive sound similar to vacuum tube amplifiers), but at this time due to RC filter to remove some excessive high frequency Harsh. Two high- and low-frequency EQ controls of the Baxdall type further shape the enhanced overdrive sound of various frequency bands.
Note: Maximum amplification 35dB






In the Spark mode, a high-pass filter is used to simulate the frequency response of Top Boost, and through the AC circuit, the classic tone of Top Boost is obtained, which is a very prominent guitar tone.
Note: Maximum amplification 35dB






Let's check the demo of boosting the distortion pedal in Clean (RC) mode!



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Thursday, March 26, 2020

NUX Optima Air development introduce ( Acoustic Guitar Impulse Response)

Blog Contribution: Monk Li (Taiwan) Marketing Director NUX | Cherub Technology.

Optima Air means the best Acoustic Impulse Response loader ever.


Q: How to get a good micing acoustic sound with a line out pickup signal?

A: It's a dream for guitarists. I tried to figure out the way and got inspired by 3 Sigma Audio. I noticed using IR is the solution.
According to IR theory, IR is the way to measure the system frequency response.
The traditional IR way is using an Impulse to attack the system and measure the frequency response. It·'s ridicules to use a hammer to punch the acoustic guitar.
The convolution of IR in mathematics is similar to multiplication in Fourier integral. 
Pickup(f) * IR(f) = Mic(f) 
So we could do deconvolution as Mic(f) division Pickup(f) to get IR(f).












Q: What's the preamp in Optima Air?

A: As replication of acoustic guitar with micing. It means we need a good mic preamp. Rupert Neve is the legend in this industry, so I discussed with engineers to develop a white box algorithm ( physical modeling) of Neve 1073 with user-friendly controls.
The beauty of an analog circuit is chaos makes the muse. While you tweak the knob, it affects itself and also other parameters. For a linear digital system, the parameter is independent. So using a white-box algorithm could replicate the chaos in a compact size and features lots of advantages like USB audio stream, Reverb function, and IR Capture.

















































Q: What's the Capture?

A: As we talked about Impulse Response theory, convolution & deconvolution. So we think it should be a good point for musicians to Capture their own favorite acoustic guitar IR profile. We did a similar thing on our Solid Studio, but acoustic guitar IR uses deconvolution. So you have to play a while to let the pedal learn the frequency response.























Friday, December 13, 2019

Something you should know about 2.4GHz wireless in 2020


Blog Contribution: Monk Li  ( Taiwan ) Marketing Director NUX | Cherub Technology.

Pete Thorn wrote a review Tone Tips: Going Wireless in 2018 on Premier Guitar, he also mentioned our NUX B-2 wireless.

As a modern musician, we have to know wireless more. So let's talk some basic knowledge about 2.4GHz and wireless.
Wireless is becoming more and more popular for musical instruments, but we have to know wireless is divided into UHF and 2.4GHz.
First let's talk about UHF-Ultra High Frequency. In fact, 2.4G is also included in this frequency band. But 2.4G we mean ISM, which is the universal channel. At present, 2.4G is a universal channel that is open all over the world, and UHF must apply for a license according to the frequencies opened by governments of all countries.
This is why major brands have begun to move to 2.4GHz.
The most difficult point for 2.4G to overcome is how to avoid the interference of the WiFi router, overcome latency issue, and transmission length.

The working principle of 2.4GHz.
2.4GHz is a general term, which is actually between 2.4GHz and 2.483GHz. (See Wikipedia)
Take Shure's 2.4GHz as an example:

Shure cut the 2.4GHz band into 19 bands (NUX B-5 also cut into 19 bands), avoiding the 3 bands with strong interference from WiFi devices and the 1 band used by the pairing code, so selected 15 bands for working.
Professional 2.4GHz private protocol bandwidth is usually 2MHz (worse digital compression probably use 4MHz bandwidth), plus 1 MHz of Ramp Up / Down, 4MHz bandwidth is required.

(83-8) / 4 = 19 frequency bands (both the first 4MHz and the last 4MHz must be discarded)
As for frequency band cutting and data packet size, there is a considerable relationship between bandwidth. It can be known from the above that the digital compression algorithms of Shure and NUX are quite powerful, and the data packet can be processed very small. The most difficult thing for wireless transmission of musical instruments is how to compress the data packets small enough to keep high-fidelity sound reproduction. This is also the biggest difference between this generation of NUX B-5RC and the previous generation NUX B-2, so it can effectively reduce the power at the transmitting end and solve the problem of high-frequency interference noise of active pickups.

The sharp-eyed friend may realize that when Shure is in Group1, the system latency is the shortest, which is about 4ms. But in other groups, the system delay came to 7.3ms.
Because Shure uses FPGA instead of DSP, the latency of the arithmetic unit will be shorter than that of NUX B-5 using DSP. (Shure can achieve 4ms in Group1, NUX B-5 < 5ms)

The method in Group1 is that each channel of the transmitter uses 6 frequencies for transmission at a time (actually only 3 frequencies work, for example, 2424 and adjacent 2425 actually only have one transmitting, and at the same time, transmitting and receiving will detect the current working environment evaluates whether automatic frequency hopping switching avoids interference.), And the receiver only needs to receive a data packet of one of the three frequencies. At this time, the receiver does not return a signal to the transmitter, so only once transmission can minimize the latency. However, since there is no Protected Access, Shure uses 6 frequencies at a time to take into consideration the frequency hopping during work to avoid signal drop. (The more transmission frequencies, the lower chance of signal dropping, and the fewer transmission frequencies, the higher chance of signal dropping.)

Note: NUX also adopts the method of 3 transmitting frequencies but does not have frequency hopping during work (mainly considering that B-5's compact size,
low power consumption and standby time), while the Boss WL series and Line6 G10 only use two frequencies to transmit, so it will be more susceptible to interference than the B-5. Therefore, the signal stability is Shure GLXD> NUX B-5> Boss WL / Line6 G10.

The method of Group2 is to transmit at three frequencies + the receiver notifies the transmitter to hop:
Because this method is to inform the transmitter whether to switch frequency hopping through the receiver, the system latency comes to 7.3ms.
But the advantage is that the probability of missing data packets is lower than that of Group1. So it is also the choice of the balance between latency and missing packets.

Group3's approach is to transmit at 2 frequencies + the receiver notifies the transmitter to hop:
For example, Group3 / Channel1 uses 2415, 2416, and 2443. In fact, only one of 2415 and 2416 transmitted, and 2443 is transmitted in sequence. At this time, the receiving end only needs to receive one data from them. If the current 2415 will drop the packet, the receiver will notify the transmitter to jump to frequency 2416 to work.
The biggest difference between Group3 and Group2 is to sacrifice the chance of dropping packets to meet the possibility of 8 groups of devices working at the same time.

The method of Group4 is similar to the Bluetooth communication protocol. It adopts the method of cyclic transmission. The advantage of this method is that the possibility of dropping packets is minimal, but the disadvantage is that the system latency is very long. And this makes it impossible to work with other equipment at the same time.
So Group 2, 3, 4 is the choice between "the quantity of simultaneous working groups" and "the probability of dropping packets."

Therefore, the 2.4GHz wireless system is a kind of trade-off between "signal strength", "transmission distance", "pickup noise interference", and "digital compression algorithm to reduce bandwidth" and "keeping high-fidelity sound quality".
The most difficult part is the "digital compression algorithm", because this product can be called a "professional product" only if it can effectively compress the packet and keep high-fidelity sound quality.

Supplementary note: The shortest latency of B-5 system can be 3.8ms ~ the longest is about 4.8ms:
B-5 uses 3 frequencies for transmission, and the 3 frequencies send out signals in sequence. If the receiver receives the first transmission, the system latency will be the shortest 3.8ms. If it is received on the second transmission, Arrived, it is about 4.3ms. If it was received on the third transmission, it would be 4.8ms long.

NUX B-5RC 2.4GHz Wireless System
B-5RC wireless system fits in perfectly with all types of electric guitar, acoustic-electric guitar, bass guitar, Ukulele. Enhanced by the latest wireless technology innovation and upgraded algorithm, B-5/B-5RC can now work well with instruments that equipped with active pickups.

Moreover, it comes with the ground-breaking auto-matching system which allows you to enjoy complete freedom without any setup. Enjoy, have fun & rock on.
No buzzing/humming with active pickups.
You’re looking at the most compact wireless system that works well with active pickups. No more buzzing, humming, high-pitched noise,this system only delivers crystal clear guitar tone audio @ 24-bit/44.1kHz with less than 5ms latency.


Auto-matching system: no setup required.
Forgot about the channel-matching thing, B-5/B-5RC can work straight out of the box. Just turn on both the transmitter and the receiver, plug them to your guitar and amp accordingly, and you’re good to go.


Stay charged, always! 

System Latency <5 ms

Large Dynamic Range 112dB
For a consumer-grade wireless product, the dynamic range of 112dB is already considered to be excellent. The average digital effects are almost in the vicinity of the dynamic range of 110dB.
Note: The dynamic range of the entire Boss WL series is 110dB. The sampling rate of Line 6 is basically less than 44.1KHz, and the Xvive is about 105dB. Only the Shure GLX-D has reached a very high level of 120dB.

Ultra-low system noise
When using 1K frequency to test the system noise, the system noise of B-5 is about -130dB, which is about 3uV.

Note: Generally speaking, the system noise of excellent audio equipment is acceptable within -120dB. (Probably 10uV) And the white noise like a guitar amplifier is basically larger than the B-5.




Ultra-high system Headroom
B-5 can start to be distorted up to 2.2Vrms, which translates into a signal range of 2.2 x ± (√2) = ± 3.263 V
Note: The signal range of the passive guitar is about ± 1V
         Active guitar signal range approx. ± 2V
         Active bass signal range approx. ± 3V
So this is enough to prove that B-5RC is used for active circuits and active basses, and there is no problem! !!


Optional Cable Tone simulation
The B-5RC provides Cable Tone simulation of about 3 meters length. After turning on the power, as long as the receiver button is pressed briefly, the indicator light turns orange to represent Cable Tone.
The pink line is the frequency response curve of the Cable Tone, and the red line is the frequency response curve of the normal mode.
Compared to the Line6 G10 fixed type, which can't choose to engage or disengage the Cable Tone, and Boss also distinguishes between WL-20 and WL-20L models with or without Cable Tone, the NUX B-5RC is very friendly.


All types of guitar jack friendly


Comparison Chart
What's the difference between B-5 , B-2 and others?

NUX B5-RC works like a guitar cable but offers wireless freedom. Setting up the system is simple: choose your channel on the Transmitter & Receiver, and is ready to go.