Inside the OB van recording system for AKB48 9th Senbatsu election

CG-2000

The TASCAM DA-6400DP, IF-DA64 Dante interface card, IF-MA64/EX MADI interface card, and CG-2000 were introduced in the OB van system recording AKB48's 9th Senbatsu election's audio. Although record-heavy rainfall forced a change of location, it was a calm atmosphere from start to finish once the election began. TASCAM got the chance to interview Minoru Hamasato of Third Wave Inc. who designed the recording system.

TASCAM: Please tell us why you decided to install the DA-6400DP and CG-2000 in this system.

Hamasato: When we were considering the construction of the recording system for the election, the DA-6400's simple system and stability were very appealing as a stable backup device capable of recording 96 tracks. The main reason is that in this system, Dante and MADI are mixed, so the DA-6400 can be used as a converter for both, and in Okinawa, where our equipment is limited, it is possible to build a stable system by making full use of the DA-6400's many functions. The CG-2000 was introduced into the system at the request of CGF’s recording coordinator, Mr. Tsuruta.

~ Notes from Hiroto Tsuruta of Cherry Guns Factory Inc. ~

By regenerating the video sync signal from the relay car with the CG-2000 and using it as the master clock for all devices in the relay car, not only can video and sound be synchronized, but even if the video sync signal is interrupted, the system can continue to generate a master clock that matches the video sync signal that has been received, so that when the video sync signal returns, the audio equipment operation is not affected.

The CG-2000 and DA-6400 inside the OB van

Technical explanation:
The glitchless relock circuit prevents noise/sound loss in the event of clock dropouts/recovery
The CG-2000 constantly measures an external reference clock, and when a clock dropout occurs, the CG-2000 uses a high-performance holdover technology to maintain a pseudo-reference clock. During this time, the phase between the video reference and word clock is maintained, and when the reference clock returns from a dropout, it is resynchronized to the recovered reference without producing glitches, preventing video/audio noise and sound loss.

The planned system design

TASCAM: Looking at the system diagram, the system is a mixture of Dante and MADI. Did you have any reason for having both?

Hamasato: We had to run a DAW after receiving the timecode from the video relay car, and we needed to run Pro Tools on MADI due to the equipment we own. I chose a YAMAHA CL-5/QL5 as the main mixer because I could get all the equipment within the prefecture, and so I ended up with a mixed system of Dante and MADI. Good thing is that the DA-6400DP also can receive a timecode.

TASCAM: It's mostly common for customers to use a DAW and the DA-6400DP for backup, but this is the first time we've seen these many recorders, which in this case you used 3 DAWs and a DA-6400DP unit. Do you have any background or policy behind the decision to run so many recorders?

Hamasato: Rather than a recording system that is always in operation with a relay car, this was only a temporary recording system and it's somewhat impossible to predict what kind of trouble might occur, so many DAWs were used in operation. We used a Pro Tools system as the main DAW, Studio One as a subsystem, and the DA-6400DP as a backup. We also used a MacBook Pro with Studio One as our stage-side DAW, which was patched directly from the Rio3224 stage rack via Dante. This was a safety measure to be able to record even if there is a problem with the mixer in the OB van.
In a temporary recording system, equipment such as the DA-6400DP that can record up to 64 tracks in 1U is an attractive feature when it comes to the limited space of a relay vehicle.

MADI and Dante systems combined

Inside the OB van

TASCAM: Unfortunately, the general election was held at a different location at short notice due to the record-breaking rainfall. Did you have any changes in the system after that?

Hamasato: There were no systemic changes, but some equipment was no longer used due to the reduced number of channels. In the Dante system, routing changes can be made flexibly with the Dante Controller, which is convenient.

TASCAM: What was the sampling frequency and bit length of your system, and how many channels were recorded at DA-6400DP?

Hamasato: 48 KHz/24-bit. The recorded number of tracks was 96 tracks, but it became 27 tracks only for the general election opening event. So I used the second DA-6400DP as another backup unit.

TASCAM：What are your thoughts after the recording using the DA-6400DP and the CG-2000 was finished?

Hamasato: I operated the DA-6400DP in various ways before the election and found it very easy to understand and has excellent operability. The stability of the DA-6400DP also exceeded my expectations. The CG-2000 also provided a stable clock without a single clock error in this complex system.

TASCAM: Please let us know if there is anything in particular that you liked about the devices.

Hamasato: When it comes to dedicated devices, I think they both have great stability. Also, the Dante/MADI conversion, which is what made me want to use the DA-6400dp this time. It can do the conversion and multi-track recording. I think it's the best value for the money!

TASCAM: What about the sound quality?

Hamasato: After the recording, we compared the data from each DAW in the studio and were very satisfied with the sound quality.

TASCAM: Do you have any requests/expectations for TASCAM in the future?

Hamasato: Since multi-channel live recordings are becoming more popular, I think it would be simpler to operate the DA-6400DP with a cascade function and to control the system settings via the iPad app. TASCAM has been producing several high-quality sound products, such as the DA-3000, and I look forward to seeing more products like that in the future.

TASCAM: We are currently preparing for the release of V2.00*, which will also support the cascade function. Thank you very much for your time today.
*As of November 2017

Profile

Minoru Hamasato

Producer/recording engineer

Hamasato founded Third Wave, Inc. in 1995. While running a musical instrument rental/recording studio, he also worked as an artist manager and sound producer. He produced/engineered MONGOL800's early days, after which became the first indie band to sell 3 million copies. In 2004, he established Third Garage Studio and he has been involved in many live recordings in Okinawa recently.

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