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The Definitive DTRS Guide, Chapter 7: Tascam DA-78HR
|Copyright © 2010 Silent Way. Unauthorized reuse is prohibited.|
Tascam DA-78 Special Report
Tascam released the DA-78HR digital audio recorder around January 2000. Its "bigger brother," the DA-98HR, arrived a bit later. These 8-track recorders were backward compatible with all 16-bit DTRS recorders. When put into High Resolution mode, they were also capable of storing 8 tracks of 24 bits to tape, and they do so without speeding up the tape, thus retaining the DTRS tape length. The DA-78HR and the DA-98HR have been discontinued.
The DA-78HR (original list price $3399.00) sports 24 bit converters, SMPTE timecode sync, and SPDIF digital I/O. It has an internal 8x2 MIDI-controlled mixer with panning and read-before write capability. This means that you can internally MIX all 8 tracks down to two tracks, or mix tracks 7+8 onto track 8. Other new features: storage of settings/locate points onto a tape, a record mute function, and the LED level meters can double as indicators for track routing, errors, track delay, etc. There are In, Out AND Thru jacks for both Word Clock and MIDI. The DA-78HR resembles a DA-38: it is 3 rack-units high and weighs about the same, but the DA-78 has a darker front panel. It retains all of the features of a DA-88 (with SY-88 sync option) and DA-38, and it stores 24 bits! It does not have 9-pin control for video post-production, and it does not clock to video (but is does clock to Word, TDIF or S-PDIF). For more info, see Tascam's site.
There are a few weird issues with this deck. But don't forget that the converters sound great and it is very inexpensive for an 8-track 24 bit recorder. I consider the timecode and post-production functions to be one big set of "hidden functions," which you really don't even pay for at this price. These functions are hard to access, but if you think of them as a free bonus, then they are worth every penny. Don't expect to use the DA-78 on your next Star Wars movie, but it's perfect if you only have occasional timecode needs. The DA-98HR is available to serve as the lead machine and take care of the professional timecode functions. The DA-78HR is a perfect 2nd, 3rd, etc deck in that application.
The 78 is great, but... here are issues to watch out for:
- How to avoid errors with the right tape
The most important consideration is that the DA-78 is much more sensitive to errors than previous models. The official recommendation from Tascam is to use Fuji tape. I agree. Most DA-78 users used the Fuji DPD-60MP and DPR-113MP, but Fuji stopped making it in 2007. See this page for mor eon tape choices.
Tascam also recommends using a "quick-clean" method. This involves the dreaded dry-cleaning tape (see the DTRS guide chapter two), which ordinarily causes excesive headwear. However, if the dry-cleaning tape is inserted WITHOUT putting the deck into it's "cleaning mode," it will only briefly touch the heads before being automatically ejected. I have opened up the deck during a "quick-clean" to confirm that this is true. This method will not create as much headwear as the usual 5-second pass when in "cleaning mode." Check error rates regularly in the error-rate window ("Maintenance"-->"Block Error").
To find places to buy tape, check The Silent Way Directory's Blank Tape Dealers links. My favorites: Comtel or Tape Warehouse.
- Software updates
To determine the system software version of the DA-78HR:
Menu Maintenance--> sub menu Version. The display shows the internal system software version. Press the UP-arrow button to access the "Front" and "Servo" versions. Contact Tascam for the latest.
The software version is 1.17, as of 5/2005. (It was 1.14 as of 1/2004. The previous version, 1.13, was current for a few years.)
Before 1.13, there were a few quick software updates in a row, which brought the DA-78 up to system 1.08 as of 11/00. 1.08 had many problems. One which I witnessed is a situation which mutes the outputs after using the shuttle mode. Before the update, the user was required to press "STOP" after shuttling in order to unmute the outputs. Also corrected in later versions is compatibility issues with remote controllers. Contact Tascam about getting the free EPROM chip update (they may charge you a deposit until you return the old chip). It's a slightly different chip than the DA-88, but still easily installed. See pic of the board below, and note the system software chip in the bottom right corner.
- Timecode track does not stay in record- Fixed in v. 1.13
There is a DA-78 timecode-related design flaw that users have successfully petitioned to have changed. When the timecode track is armed and recording, after you push stop the 78 un-arms the time code track! Thus you need to go into the deep submenu each time to re-arm the TC track. It should default to "stays on," with a new submenu item allowing the user to put the deck into a "turns off after record/stop" mode.
"There are now three settings for time code recording.
Once-Works just like it always has. When you push STOP time code stops.
OFF-Time code recording disabled.
On-The way you're used to it on the DA-88 and DA-98. You can push STOP and time code will just keep on going.
You can toggle between On and OFF by pushing SHIFT and CLOCK. Instead of using the menu structure."
- "Low Batt" message, Replacing the Battery and "premature battery death" syndrome
As most DA-78HRs get less action these days, there is a greater likelihood that you will see the "low batt" message. This just means that the internal battery that stores some settings has died. Press the "stop" button to make it go away. To prevent this, you can leave the DA-78HR plugged into the wall. Or, replace the battery.
Remember that you will lose most of your settings, but not the headhours, when the battery is dead or removed for replacement. You can store some settings to the head of a tape, and recall them from that stored location. These functions are in the "System" menu , labeled as "save" and "load".
The battery can be replaced with Radio Shack CR-2032 lithium battery, catalog #23-162 ($2.79). The battery is mounted vertically in its holder (see picture). To remove it, push down slightly and then push back (toward the rear of the 78).
When the DA-78HR was first manufactured, there were battery issues. Quite a few DA-78HRs were having dead batteries WAY too soon, as evidenced by "Low Battery" warnings on startup and loss of settings. According to Tascam and users reports on the (now defunct) Tascam Users' Forum, "there is a problem with the value of one resistor." Their first solution was to give you a bunch of free batteries. Their first diagnostic guess was incorrect, regarding the battery holder which was supposedly making inappropriate contact and draining the battery. Thus the "electrical tape fix" will not work.
- Balanced input can't take "impedance" balanced signal
This pertains to certain "impedance" balanced outputs, which the DA78HR's balanced inputs do not like. Basically, if a mixer's outputs are "impedance" balanced and not truly balanced, the DA-78 will not get a true +4 input level. A few examples are certain Mackie mixers, the Presonus DigiMAX mic pre, Presonus M80 (1/4" send jacks only) and one user's Dolby XP rack.
For a definition of impedence balancing read this definition at Sweetwater.
A quick fix for the Presonus units' 1/4" outputs is to use a unbalanced 1/4" cable into the 78HR's +4 inputs. This fixes the problem because the Presonus outputs are servo-balanced and will sense the fact that the tip and ring have been bridged. Perhaps this would work with other manufacturer's units if they are servo-balanced? A second choice is to use an unbalanced 1/4" to RCA cable into the 78's -10 RCA jacks. The signal will be 14 db hotter, so you might have to bring down your mic pre gain.
A long description from Jace at Tascam (originally on the Official Tascam Forum, which is no longer online)...
" The meters on the DA-78HR are exactly the same as the meters on all of the previous DTRS machines. They function exactly the same. However, the analog signal path to the new A/D converter is different. In the past once the signal was received at the input, it was changed to an unbalanced signal and sent to the converter. Our new superior converter called for a balanced signal at its input. If the unit receives a truly "balanced" signal your meters will function normally. But if it receives an "impedance balanced" or "quasi balanced" signal that doesn't provide the proper input level, your signal will distort earlier then usual and thus your meters will not peak.
Some manufacturers do not send a truly "balanced" signal from their console even though they use a standard "TRS" connector. They use what is called an "impedance balanced" signal. Usually with a "balanced" signal you have half of your signal on the positive wire (usually pin 2), half of your signal on the negative wire 180 degrees out of phase with the positive (usually pin 3) and a ground (usually pin 1). The two signals sum at their destination and reject any common noise.
An "impedance balanced" signal sends all of the signal on the positive wire and only the proper impedance on the negative wire as well as a ground on pin 1. Because the signal is not properly balanced from the beginning, the DA-78HR is not able to get the proper signal to the converter. Once again previous converters in previous DTRS machines did not require this. So those machines didn't react the way that the DA-78HR does. So, you have a few choices on ways that you can handle this problem when using the DA-78HR.
If you have a console that has a +4/-10 switch for the outputs, you could use a 1/4"-to-RCA cable and connect to the machine at the -10 RCA inputs. Your meters will function normally. For those of you who do not have a +4/-10 switch TASCAM is offering a free modification to your DA-78HR's -10 RCA input path. This will lower the input signal by 12dB allowing you to send a +4 signal in to the RCA connections. Your meters will again function normally.
Keep in mind that you will not have any way to get a -10 signal into your machine after this modification has taken place. This will not change the signal path of the balanced D-SUB connectors in any way.
This explains why some people are having trouble while others report that everything is functioning normally. Some consoles send a truly "balanced" signal and some don't.
So make sure that the signal you are sending the DA-78HR is "truly balanced." If you are experiencing the meter problems that some users have posted here on the BBS, I can almost guarantee you that this is the problem. We've tested this quite thoroughly and have confirmed our findings with a few console manufacturers. If you're unsure about your mixing console please contact the console manufacturer and find out for sure.
Thanks- Jace "
- from a post by Jace, TASCAM Product Specialist and Moderator on the Tascam DTRS bulletin board, 10/10/2000.
"To the best of my knowledge all of our analog mixers include impedance balanced outputs." (But, perhaps this person might have thought that I was just asking whether the outputs were balanced, not knowing that "impedence balanced" is different and not the standard.)
- Mackie Designs Tech Support (800-258-6883), 10/31/00.
"Q: Is the quarter inch analog output of the DigiMAX fully balanced?
A: The analog outputs are impedance-balanced, not fully differential. This means that the tip carries the full signal with an impedance of 51 ohms. The ring simply carries an impedance of 51 ohms, no signal. That particular conductor is not left 'hanging', but is referenced to signal ground, and should be referenced or grounded on the receiving end. This is in contrast to a fully differential system that would assign half the signal voltage out of phase with one another to the tip and the ring. The impedance would remain 51 ohms on each conductor. The result is that both systems have almost identical noise rejection characteristics."
- Presonus DigiMAX FAQ, no longer on their site.
If you have a Mackie, look into this problem. Call Mackie and ask for a straight answer about your particular mixer's outputs ("Are they impedence balanced?"), and refer them to this webpage. Some folks at Mackie know about the problem, but some don't. Ask for someone higher in command if you don't get a satisfactory answer.
- Wordclock termination
Yet another hardware design flaw is easily fixed. The word clock input jack is not terminated correctly.
Get a BNC "T" connector (Radio Shack part #278-270) and a BNC 50 ohm terminator (RS part # 278-112). Make sure that the terminator is not 75 ohm. Connect the terminator to one side of the T, and plug the T into the Word Clock input. Plug your clock source into the open side of the T. The THRU is self terminating as long as nothing is plugged in to it.
- Mixer output unity gain level
The Tascam DA-78 has a built-in digital sub-mixer, but there was no indication of what unity gain is...
"Set the Master Level to 127 and the individual track levels to 100. At these settings, the output of mixdown mode appears to be unprocessed. Each time I did this, I was accurate within 1/10 of a decibel!"
- from a post by "big g" on the Tascam DTRS bulletin board, 08-21-2000.
- How to reprogram the startup message
My suggestion? Try "Hey Tascam, hire an ergonomics tester!"
1) Press shift so the SHIFT LED blinks.
2) Press HR MODE and MENU until the display reads "mAintn2".
3) Press SUB MENU until the display briefly reads "mSGEdit". The counter will then display "1. T" and a "T" will scroll across the meters.
4) Press UP and DOWN arrows to change the letter. Some letters will not show in the counter, but will show in the meters.
5) Press SHIFT and UP to enter the letter and move to the next letter.
6) When you're done, select "End" as the last character. Pressing SHIFT and UP once more will display "PrEViEw" in the counter and your new message will scroll across the meters.
7) Press SHIFT to exit.