Oade Brothers Audio


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Roland R26
Roland R44
Roland R4 Pro
Roland R88
Fostex FR-2
Fostex FR-2LE
Marantz PMD-671
Marantz PMD-660
Marantz PMD-661MKII
Marantz PMD-561
Marantz PMD-620MKII
Tascam HD-P2
Tascam DR-100
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General FAQ

Recorders that work well for the applications listed below



   Minimum Microphone Input Level (Max Gain):



PMD 620 Basic

PMD 620 Concert

PMD 620 Super

PMD 660 Basic

PMD 660 ENG

PMD 660 Ambient

PMD 660 Songcatcher

PMD 661 Super

PMD 661 FET

PMD 661 Concert

PMD 671 Basic

PMD 671 Advanced

FR2LE Basic

FR2LE Super

FR2LE HD

FR2LE WMOD

HDP2 Super

HDP2 Super+6dB

HDP2 HD Upgrade

Edirol R4 Concert

Edirol R4 Ambient

Edirol R4Pro Concert

Edirol R4Pro Ambient

Edirol R44 Super

Edirol R44 Concert

FR2 Super


Minimum Signal Level - 50dBV

Minimum Signal Level - 44dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 54dBV

Minimum Signal Level - 57dBV

Minimum Signal Level - 57dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 60dBV

Minimum Signal Level - 60dBV

Minimum Signal Level - 54dBV

Minimum Signal Level - 55dBV

Minimum Signal Level - 55dBV

Minimum Signal Level - 54dBV

Minimum Signal Level - 54dBV

Minimum Signal Level - 48dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 56dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 56dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 56dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 50dBV

Minimum Signal Level - 60dBV


How do I set the Microphone attenuation on my PMD 620 or 661?


    It's important to understand the MIC ATTN settings in the PMD 620 and 661 are not pads, they actually alter the gain of the preamp. Always use the least amount of gain that will allow you to get to 0dBFS, this means using the largest negative number (i.e. -18dB or -24dB). This does 2 things, it lowers noise and distortion plus it prevent input overload or "brickwalling". It's OK to set the PMD 620 or 661 record level control at 10 as long as your meters never show an over load. This is preferred to using a higher gain setting( smaller negative number) and setting the record level control to 6. If you cannot get enough signal level, then and only then switch to the next highest gain setting (i.e. -12dB)


Which recorder is easiest to use ?


    Without a doubt, it is the PMD660. The layout and menu are very easy to use. It has superior ergonomics. With microphones cables that exit the rear of the machine, not the side, it fits over the shoulder with a minimum chance of getting in the way. It offers 3 ways to set levels, ALC allows the machine to worry about setting record levels for you while ALC + manual allows you to do worry free recording while having some control over the action of the ALC circuit and for the more advanced user, a pure manual setting is available. Three presets makes it easy to set up ahead of time for different recording situations. These features allow for quick, reliable and repeatable setups that will give you the confidence you need to concentrate on the subject and not the technology. Plus the Marantz PMD 660 has proven itself to the be most reliable machine Oade Brothers Audio has sold in nearly 30 years of business !


What software do I need to edit my audio ?

    Any audio editor will do, many on a budget use Audacity as it is open source and therefore free to use. Audacity is a full featured audio editor that many high end manufacturers, like DigiDesign, ship with their less costly products.
    Helpful Link for Audacity


Do I need 16 or 24 bits ?

    Odds are if you are not sure, 16 bits are fine. If you want to make recordings for use as CDs or for MP3s, 16 bits is preferred. Keep in mind moving from 16 bits at 44.1 KHz, the CD sampling rate, to 24bit 48KHz, the DVD sampling rate, requires 50% more storage space, 24/96 doubles that storage requirement. This means you get less record time for a given memory card and less storage (i.e. recording time) on your hard drive or archive medium. If you are recording as a professional that is charged with archiving audio for the future use, 24/48 or even 24/96 is required. If you are recording music or sound that will undergo post production the additional resolution that 24 bits provides is helpful. If you are recording music for DVD, 24 bits is an improvement that is easy to hear. As a general rule of thumb the microphone is much more important than the use of 24 bits so if your budget is tight, spend more on the mic and less on the deck and storage. Simply stated the recording cannot possibly achieve better quality than the microphone is capable of delivering. The other significant consideration is the mic preamp. Many preamps for popular 24 bit machines use chips and capacitors that have artifacts that are down only 85dB to 95dB. If the signal you are recording is from a microphone, it is typically down 40dB to 50dB so the resulting dynamic range is 85dB to 95dB less 40dB to 50dB or not very good ! A 16 bit A/D chip has a dynamic range of 96dB, more than enough for these preamps. You want as much of a difference between the desirable signal and the residual noise and distortion of the preamp as possible. With an input signal down at -40dB to -60dB you need microphone preamp artifacts to be as low as possible as the preamp amplifies both the desirable signal and the undesirable artifacts. We use preamp chips with THD+N down from 110dB to 130dB that cost as much as 50 times what the stock chips cost. The result of low grade parts in a mic preamp is performance that is not even 16 bits, this makes 24 bits with a poor preamp of questionable value. A typical 24 bit machine's preamps Spurious Free Dynamic Range is no where near the 144dB dynamic range of 24bits and most do not even achieve 16 bit quality. Even some of the best op amps, the chips used in digital recorders, have no more than 120dB SFDR and most stock machines typically use chips that have a SFDR of less than a 96dB.


Batteries and Memory Cards


    Running your portable digital recorder in the field with high reliability demands both good data storage and good power.

    The LaCrosse BC-900 or MAHA MH-C9000 Battery Charger will allow you to use internal AA cells with confidence. No other chargers I know of are capable of delivering the performance and reliability of these impressive systems. Used with Duracell or other high quality AA NiMH cells they will power your rig reliably. These chargers will let you know the condition of the battery before you take it into the field. They will also refresh the cells which cycles them until they reach maximum capacity, This should be done periodically or after the batteries have sat unused for a period of time. When using non rechargeable batteries, lithium perform the best as they provide the longest run time and are less affected by cold weather. One last point, it's a bad idea to leave batteries in a portable recorder when it's not going to be used regularly. The batteries can leak causing severe damage to the recorder. Plus, when batteries are left in the deck, it's always in the sleep mode waiting for the power button to wake it up. This can cause the deck to lock up, requiring the batteries be removed in order to clear the problem.
    LA CROSSE BC-900 Battery Charger
    MAHA MH-C9000 Battery Charger

    Memory cards are an integral part of your digital field recording system. Why risk loosing audio or having ticks, pops and other digital artifacts in the sound when a high quality card can prevent that ? While there are many brands available not all brands work well for digital audio. Guessing at which card to use can be risky. Stick with Lexar or Panasonic memory cards for the best results. If you are recording at 24 bits and 48Khz, a class 6 card is fine. For higher sampling rates and 4 channel recording, use a higher class card. If the length of the recording requires the creation of another file, the higher speed card insures the new file will be created and written to without the loss of any data. Recorders that use memory cards must initialize the system with the card working correctly. If the deck will not power up, the card may be the trouble. It's a good idea to periodically reformat the card in order to optimize it's performance and as a test to verify the card is working correctly. When buying a new card, be sure to check it's class rating as well as do a test run before you rely on it's performance on a job. It's easier to do this than redo the work because of ticks, pops and digital artifacts in the sound. SD cards have not proven to be as reliable as CF cards, due to the nature of the design plus the plethora of lower cost cards that do not work well for audio. The exposed contacts must be kept clean, it's a good idea to store spare cards in their plastic case and avoid touching the contacts. Periodically removing and reinserting the SDHC card can help wipe the contacts keeping them clean and insuring more reliable operation. If your memory card recorder exhibits any problem, try the deck with a different memory card. If you don't have the card it came with, use a Lexar or Panasonic brand card. We are also seeing issues with card access speed. That is why we like to see at least a class 6 card for HD audio. A card that works well for a still camera may not be usable for HD audio. If the card test well for HD video camera work, it will do well for HD audio, both require a sustained high data rate.


Should I update the firmware on my recorder ?

    I NEVER do a firmware update unless I have a problem with the device. A common reason to upgrade the firmware is to enable the recorder to use newer memory card designs. For example, the original Marantz PMD-661 could only use up to an 8 gig SDHC card. The firmware must be updated to use larger cards. If you have the "bug" and must do it, you should always wait at least one month to see if they got it right. All too often a firmware change causes trouble. It is also possible your computer may have a problem that corrupts the data rendering your recorder useless. A power surge or power outage is another possible source of a firmware change failure. If you have battery back up for your computer, plug your recorder's AC adapter in to the UPS. If you have a memory and CPU diagnostic, run it before you attempt to alter the firmware. Many manufacturers will not provide support in or out of warranty should the firmware update fail, be sure to read any documentation provided prior to installing the update. Please keep in mind that if you attempt to change the firmware and it fails, this is NOT covered under Oade Brothers Audio warranty and a service fee may be charged to clear the problem. If the deck we sold with an upgrade has a problem, please contact us prior to attempting a repair.
    IF IT AIN'T BROKE, DON'T FIX IT !


How do I set levels on my recorder?

    Portable recorder's internal microphone preamplification designs can be divided into 2 broad categories. Those that use a fixed gain preamp and employ a resistor PAD to allow for higher input signal levels and those that have adjustable amplification of the mic signal. Adjustable gain is preferred because it minimizes noise, distortion and the possibility of overload (a distorted signal). A quick check of voltage feedback op amp (chips used for mic preamps) preamp circuits reveal they have the lowest noise and distortion at lower gain, thus one should apply the least amount of gain in the preamp to achieve the recording level needed in order to minimize THD+N as well as provide the highest headroom possible. Only current feedback op amps have relatively constant noise and THD at all gain settings. Very few preamp circuits use them and they are not compatible with voltage feedback chips so they are not interchangeable, i.e. cannot be used to upgrade most preamps.

    Marantz PMD 660: The PMD 660 has a fixed mic preamp gain with a resistor PAD that reduces the input signal to the preamp so it can be used to record very loud sounds. The only time you want to set the 660's MIC ATTN to -20dB is if you are recording with the record level control below 10:00 or if you hear distortion on loud signals.The advantage of this design is ease of use.

    Edirol R44 and R4Pro: When recording soft sounds, basically you want to use as little preamp gain (this is how much the preamp amplifies or increases the signal from the microphone) as possible. So you start with the smaller, inner knob, it's the one closest to you, set at about 2:00 to 3:00, then adjust the outer knob, it moves in 6 dB steps and displays on the LCD readout, until your signal level is around -12dB on the meter. You then tweak the level with the inner knob, it's okay to have it set to max and that is better than moving it toward 12:00 and adding 6 dB of gain with the stepped input trim knob. I like to target between -12dB and -6dB for peak levels when I'm recording, that way when I'm surprised, it does not overload and distort. It's a good idea to use the limiter as you learn. The limiter is a circuit that can momentarily reduce your signal level so the sound does not distort as the digital recorder runs out of bits. A digital over sounds bad and should be avoided. The key is you get the lowest noise and distortion when the outer knob ( that works in 6dB steps) is set as low as possible while still providing a good signal level. Both the outer knob that adjust the input gain in 6dB steps and the inner knob that is continuously variable and allows you to fine tune the signal level are digitally controlled analog gain stages. This simple rule, using as little preamp gain as possible, will help you to make the very best recording possible with your gear. Roland recorders have a built in feature call Autosens which will check your gain settings and make suggestions to insure you heve the best gain structure possible.
    Please note, in an effort to reverse the flood of bad info circulating in some recording forums, I suggest reading the technical specifications for the AK4620B series of ADCs used in the R4Pro and the R44 which is available for download from the manufacturer's website or the link below. This confusion stems from the use of a marketing block diagram intended to show the last gain stage and limiter are in the A/D chip. It does not show signal flow thru the chip. If that block diagram was based on engineering then you would not be able to achieve 24 bit resolution and you would have have a useless limiter !
    From the technical documentation : "- Input PGA: 0dB to +18dB, 0.5dB/step (for single-ended input)" This is a digitally controlled analog Programmable Gain Amplifier that is controlled by the inner gain knob. Furthermore, the block diagram, supplied by the A/D converter's manufacturer, clearly shows the PGA or analog gain circuit ahead of the analog to digital conversion process in the signal chain. This is essential or 24 bit resolution could not be achieved. Furthermore a digital limiter post A/D conversion is useless. I strongly suggest you not set the inner knob to 12:00 and add gain in post, this compromises the quality of your recordings.
    It's equally obvious there is no digital gain stage in the AK4620B series of A/D converters but there is digital attenuation and a digital output mute function.

    AK4620B technical data sheet
    Note on page 23 :"The IPGA is an analog volume control that improves the S/N ratio compared with digital volume controls."

    Marantz PMD 620 and 661: These newest designs from Marantz offer variable mic preamp gain that can be set within the menu system. Basically you want to use as little preamp gain (this is how much the preamp amplifies or increases the signal from the microphone) as possible. This is accomplished by setting the MIC ATTN signal first to -24dB on the 620 or -18dB on the 661. This is not a pad, it actually changes how much gain (amplification) the preamp applies to the microphone signal. Using less gain means less noise, less distortion and no overloading or "brickwalling" of the mic preamp. This is something you will not see on the level meter. The only time you move the MIC ATTN to the next step down in gain (a smaller negative number) is if you cannot get enough signal level at the current setting. This simple rule, using as little preamp gain as possible, will allow you to make the very best recording possible with your gear. Once you have set the MIC ATTN, check your signal levels while observing the meter on the LCD. On the 620 and 661, set the record level control to 7 and then put the deck into the record mode and check your signal levels. I like to target between -12dB and -6dB for peak levels when I'm recording, that way when I'm surprised, it does not overload and distort. If increasing the record level setting to maximum does not allow you to get to 0dB on the LCD meter, then switch the MIC ATTN setting to the next gain setting, -12dB on both the 620 and 661. Now check your levels again, if you cannot get to 0dB on the LCD meter, change the MIC ATTN to the next setting, 0dB on the 620 and -6dB on the 661. You should not have to use the 0dB setting on the 661 except when using a dynamic mic ( one that does not need power) or you are recording very low signals, like nature sounds but even then, -6dB will sound better.

    Fostex FR2LE: Like the R4Pro, R44, PMD 620 and PMD 661, the LE also has adjustable mic preamp gain. In the LE preamp gain is controlled by the 2 small knobs, the input trim controls, near the CF card slot. The procedure is very similar to the other decks listed here. You set the larger, record level control knob, located on the right hand side of the deck, at 2:00 to 3:00 then adjust the separate left and right channel input trim knobs, near the CF slot, to get your signal levels to -12dB. Now fine tune the levels using the larger record level control. This simple rule, using as little preamp gain as possible, will allow you to make the very best recording possible with your gear.

    Tascam HD-P2: The record level control in the HD-P2 is unique in that it actually allows you to set levels by adjusting the gain (this is how much the preamp amplifies or increases the signal from the microphone) of the mic preamp with a mic preamp gain control that is continuously adjustable. This insures that your signal quality is always optimized for the best possible signal quality by design, a very good design ! If you are new to the HD-P2, it's input selection labeling can be confusing. When the deck is set to line in, that selects the RCA inputs while the setting labeled mic selects the XLR inputs. You record XLR line in by setting the deck to XLR in and the PAD to -20dB. The controls might be more properly labeled with the LINE/MIC switches labeled RCA/XLR and the Left/Right PAD switches labeled MIC/LINE.


About Headphones for portable recorders

    Choosing headphones for a portable recorder can be tough. The single most important specification is Sensitivity. Headphone sensitivity in is rated in dB SPL per milliwatt of input. A lower sensitivity number headphone will need more power to sound as loud as those which have a higher sensitivity number. Headphones for portable gear typically needs to be really sensitive because of the lower power output of portable field recorders. When shopping for portable headphones, look for a sensitivity rating of 100 dB or greater. The ubiquitous Sony MDR 7506 or our favorite, the Sony MDR 7509HD, are both high sensitivity headphones that work well with low power headphone amps.

 
 
 

 

 
 

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