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Author Topic: Some recurrent problemas with my new Sound Devices 702 recorder  (Read 7673 times)

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Offline Ethnoaudio

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Hello Alls,

I'm a new user but not a "newbie" in sound recording. I'm a french ethnomusicologist based in north Spain (Basque Country). In november 2012 I've buyed a Sound Devices 702 digital recorder to replace my Tascam HD-P2. I've some recurrent problems in my recordings with this recorder.
I have made some soundscapes with my recorder and I've the following problem:

I've set the 702 to record in stereo mode with my Shure VP88 microphone, in the following way:

• Mic inputs: Limiter disabled
• Mic Input 1: Low Cut off
• Mic Input 2: Low Cut off
• Mic Input 1: Gain range normal
• Mic Input 2: Gain range normal
• Input nivel set to -3dB max

The VP88 microphone, used in large stereo mode (not in pure M-S one). offers the following sensibilities:

Sensitivity (1 kHz, MS mode)
Open Circuit Voltage: -66 dB (0.5 mV) Mid. (Side level 1.6 dB higher
than Mid level) (0 dB=1 V/Pa)
Side Level (Stereo mode; relative to Mid level)
Low: -6.0 dB; Medium: -1.9 dB; High: +1.6 dB

The led level meters was between -10 dB and -3dB, however I've got a very low signalin the recording (-20bD max), and was  strained to set the knobs to the maximum to obtain a decent signal.

To compare with other takes, I’ve made some musical recordings (voice and guitar) with the same Shure VP88 and two airs of other microphones : a matched pair of old “Primo” EMU-4520 (modified to admit 48V phantom power) and a matched pair of Oktava MK-102 large diaphragm microphones.

The takes were made with the level knobs set to “11 o’clock”, which was apparently the best setting gain according to the led level vue-meters to obtain a medium -3dB leval (occasionally red lightning with clipping advice set to -0dB).

The results are also a poor level recordings:

- With the “Primo” EMU-4520 best level was -15,9 dB (with the led vue meters as a mentioned).
- With the Oktava MK-102 microphones the best level was between -8,9 dB and -7,2 dB for the song

Not that I use to set my recordings to -3dB to avoid clipping and obtain a good sounding.

I make the same tests with my old Tascam HD-P2, and I obtain a good level (hear the file "Dat du min Leevste bu¨st_Oktava_HD-P2.aif").

So, what’s the problem with the Sound Devices 702? My 702 seems to have a bad calibration of the led level meters. When it appears to be satured (red lightning, I obtain only a -8,9dB and -7,2 dB with the Oktava 102, and only -15,9 dB with the EMU-4520…

I’ve contacted Sound Devices to try to resolve the problem, but they cannot help me.

Can someone help me to understand what is the matter, and to set correctly my 702 ?

Thank you for you suggestions and help.

Best regards from Basque Country.



Offline DigiGal

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Re: Some recurrent problemas with my new Sound Devices 702 recorder
« Reply #1 on: May 22, 2013, 03:38:06 PM »
What are your meter ballistics set for in the 702's setup menu?
Mics: AKG CK91/CK94/CK98/SE300 D-330BT | DPA 4060 4061 4266 | Neumann TLM 103 | Senn ME66/K6/K6RD MKE2 MD421 MD431 | Shure VP88 SM7B SM63L SM58 Anniversary Cables: Gotham GAC-4/1 Quad w/Neutrik EMC | Gotham GAC-2pair w/AKG MK90/3 connectors | DigiGal AES>S/PDIF cable Preamp: SD MixPre-D Recorders: SD MixPre 6 | Marantz PMD 661 Edit: 2011 27" 3.4GHz Quad i7 iMac High Sierra | 2020 13" MBA Quad i7 Catalina | Wave Editor | xACT | Transmission | FCP X 

Offline it-goes-to-eleven

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Re: Some recurrent problemas with my new Sound Devices 702 recorder
« Reply #2 on: May 22, 2013, 04:37:34 PM »
I’ve contacted Sound Devices to try to resolve the problem, but they cannot help me.

I'm not sure what that might mean - "they cannot help me"?

Their support is excellent and they have in the past done whatever it takes to resolve an issue. I would expect that they would thoroughly go through this issue to resolve it.  There are many different tests that I imagine they might suggest to rule out specific possible configuration and failure modes.  I won't bother repeating them here.  What did they suggest?

Have you tried reseting your configuration values to default?

What specific amount of gain are you adding on the 702, in dB?

Offline dogmusic

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Re: Some recurrent problemas with my new Sound Devices 702 recorder
« Reply #3 on: May 23, 2013, 09:24:26 AM »
Do you have phantom power turned on?
"The ear is much more than a mere appendage on the side of the head." - Catherine Parker Anthony, Structure and Function of the Human Body (1972)

"That's metaphysically absurd, man! How can I know what you hear?" - Firesign Theatre

Offline Ethnoaudio

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Re: Some recurrent problemas with my new Sound Devices 702 recorder
« Reply #4 on: May 23, 2013, 11:02:28 AM »
Hello Alls!

Thank you for your answer. I try to answer to alls here...

What are your meter ballistics set for in the 702's setup menu?

peak hold + VU, and track peak threshold st to 0 dBFS, meter stealth OFF

Do you have phantom power turned on?

YES

I’ve contacted Sound Devices to try to resolve the problem, but they cannot help me.
I'm not sure what that might mean - "they cannot help me"?


Yes, the support is excellent. We have tried with Vaughn to resolve the problem. I've send them various testing musical recordings made with various microphones, has said first: my old Shure VP88, a matched pair of Oktava MK-102 (good sensibility). The results are in my first post. Finally Vaughn said that probably I don't like as my Sound Devices 702 sounds... That not the case: the preamp are excellent. But the led

Have you tried reseting your configuration values to default?

YES. As Vaughn suggest it.

What specific amount of gain are you adding on the 702, in dB?

I d'ont understand very welle your question. I'm always using the same setting (at vue-meters): -3dB.

I remember that i've made the same recordings at the same time with my old Tascam HD-P2, and with the Tascam -3dB at the vue-meter = -3 dB in the recorded signla. It's not the case with the Sound Devices 702. At -3dB at the led vue-meters I obtain as best recorded level -15,9 dB with the “Primo” EMU-4520 and between -8,9 dB and -7,2 dB with the Oktava MK-102 microphones.

Thak you for your help.

Offline DigiGal

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Re: Some recurrent problemas with my new Sound Devices 702 recorder
« Reply #5 on: May 23, 2013, 12:04:58 PM »
Since you don't have the problem using the same mics on your Tascam it's obviously not a mic problem.   

Basically for the mic inputs you've got Normal or Low gain settings, phantom power on/off, limiters (engaged by factory default), high pass filters.  Also meter ballistics are assignable and the audio output can be attenuated by up to 40dB in 1dB increments.

Perhaps what you are experiencing is related to an output attenuation setting.  Especially since you bought it used if you can't get it resolved by toggling settings it would be advisable to send it in to Sound Devices for a full checkout and/or repairs and calibration.

Some info from the manual from manual below that may help...



Microphone Level Control

Microphone gain is controlled by the front panel recessed knobs. The gain control adjusts an analog gain stage and functions similarly to the input trim on a mixing console or stand-alone microphone preamplifier. Gain is controllable over two ranges, normal and low.

Gain Range (microphone-level only)
The microphone inputs operate in four gain ranges, NORMAL, NORMAL FADES TO OFF, LOW, and LOW FADES TO OFF. The NORMAL range controls input gain from 24.3 dB to 67.4 dB of gain. The LOW range controls input gain from 9.3 dB to 52.4 dB. The LOW ranges are useful for high SPL recording environments. The fade to off options allow for fader-like control of your gain. NORMAL FADES TO OFF provides a gain range of off or 0 to 67.4 dB and LOW FADES TO OFF pro- vides a gain range of off or 0 to 52.4 dB.

Output Meter
The meter uses energy efficient LEDs viewable in full sunlight. The 702 output meter is unaffected by shock or extremes in temperature and humidity. Meter ballistics are Setup Menu selectable among VU, Peak, Peak-Hold, VU + Peak and VU + PeakHold.
The meter uses a compound metering scale which increases meter resolution in the most important part of the scale. From −50 to −40 dBFS, each LED segment equals approximately 10 dB. From −40 to −12 dBFS, each segment equals 2 dB. From −12 to 0 dBFS each segment equals 4 dB.
Analog Line Out L, R
The analog line outputs are active-balanced line-level signals on Switchcraft TA3M locking connec- tors. The output level is a nominally 0 dBu at −20 dBFS. The output level can be attenuated from the Setup Menu by up to 40 dB in 1 dB increments. Both left and right outputs are attenuated equally.

Meter Ballistics
The output meter can be set to display any of five types of meter ballistics: VU, Peak, Peak-hold, a combination of VU and Peak, and a combination of VU with Peak-hold. The meter ballistics are selected in the Setup Menu.

VU - (Volume Units)
Ballistics correspond closely to how the human ear perceives loudness and provides a good visual indication of how loud a signal will be. In VU mode, the attack and decay of the meter signal is 300 mS. While giving a very good visual indication of perceived loudness, VU meters gives poor information on actual signal peaks and are virtually useless for tracking to the 702. In VU mode, the front panel meter labeling is in volume units.
Peak
Peak-reading ballistics correspond to actual signal maximums, but don’t necessarily correspond to perceived signal loudness. A peak meter has a near-instantaneous attack to display maximum signal amplitude and a slow decay to allow the user to see them. Peak metering is essential for digital re- cording, since signal overload can cause immediate distortion. The peak meters front panel markings are calibrated in dBFS, decibels relative to full-scale digital signal.
Peak Hold
Essentially the same as Peak metering where the peak level indication will hold for the peak level indication for several seconds. Peak-hold indicators are useful for metering in applications when an overload condition is unacceptable.
Peak/VU
The meter can simultaneously display VU and Peak level information. In this mode the perceived loudness (VU) is displayed on a bar graph, and the Peak signal on a dot above the VU. With this combination the user gets the best of both VU and Peak metering by seeing both the “loudness” of the signal and the peaks at the same time. Peak/VU is the factory default.
Peak Hold/VU
Similar to VU/Peak mode, this mode holds the peak level indication for several seconds before releasing. Peak Hold indicators are useful for metering in applications when an overload condition is unacceptable.


Output Attenuation

Analog Output Bus
Analog Tape Output
The tape output connection is stereo, unbalanced consumer output level (–10 dBV) on a TRS 3.5 mm connector. Output attenuation affects this output level.

Digital Output Bus
Just as with the Analog Output Bus, the Digital Output Bus (Bus 2) can be assigned signal sources from inputs or tracks. Sources assigned to the Digital Output Bus are exclusive and do not affect the assignments to the Analog Output Bus or headphone assignments. The same signal sources available for the Analog Output Bus are available for Digital Output Bus (see chart above).
The Digital Output Bus appears solely on the AES3id BNC output connector. The unbalanced AES3id output is directly compatible with most S/PDIF inputs.
The format for the AES3id output is selectable between professional AES and SPDIF. In either case the SCMS bit is not set.
The maximum output level is 0 dBFS and can be attenuated in the Setup Menu in 1 dB increments by 40 dB.
Mics: AKG CK91/CK94/CK98/SE300 D-330BT | DPA 4060 4061 4266 | Neumann TLM 103 | Senn ME66/K6/K6RD MKE2 MD421 MD431 | Shure VP88 SM7B SM63L SM58 Anniversary Cables: Gotham GAC-4/1 Quad w/Neutrik EMC | Gotham GAC-2pair w/AKG MK90/3 connectors | DigiGal AES>S/PDIF cable Preamp: SD MixPre-D Recorders: SD MixPre 6 | Marantz PMD 661 Edit: 2011 27" 3.4GHz Quad i7 iMac High Sierra | 2020 13" MBA Quad i7 Catalina | Wave Editor | xACT | Transmission | FCP X 

Offline Ethnoaudio

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To DigiGal

Hello again,

I'm at home after a month of field recordings, and I want to answer the last message of "DigiGal". I know all the specifications of the Sound Devices 7-series and especially of the 702 I own. Knowing theses technical specifications is a very good thing. But not resolves the problems.

In my last field recordings I've used both the SD 702 and the Tascam HD-P2, and the results are the same that I've explained in my first post about the 702...

"DigiGal" wrote: "Perhaps what you are experiencing is related to an output attenuation setting.
Especially since you bought it used if you can't get it resolved by toggling settings it would be
advisable to send it in to Sound Devices for a full checkout and/or repairs and calibration."


I've bought a a new 702, not a used one... So I don't think I need to calibrate newly the device.

Is someone able to help me resolve the REAL problem I've with the low level recordings I get with mu Sound Devices 702?

Thank you in advance.

--
R. Parejo-Coudert
Ethnomusicologist

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Re: Some recurrent problemas with my new Sound Devices 702 recorder
« Reply #7 on: June 03, 2013, 05:02:00 PM »
What specific amount of gain are you adding on the 702, in dB?

I d'ont understand very welle your question. I'm always using the same setting (at vue-meters): -3dB.

I remember that i've made the same recordings at the same time with my old Tascam HD-P2, and with the Tascam -3dB at the vue-meter = -3 dB in the recorded signla. It's not the case with the Sound Devices 702. At -3dB at the led vue-meters I obtain as best recorded level -15,9 dB with the “Primo” EMU-4520 and between -8,9 dB and -7,2 dB with the Oktava MK-102 microphones.

Thak you for your help.

1) There is a setting that will read out on the face plate just how much gain you are actually adding when you turn the dial.
2) 1 led does not equal 1db. It actually varries by where it is on that line (the last 2 green ones on the left are 10db difference, the red ones are 4db, and the orange ones are 2db as are some of the green ones in the middle). After checking the math, thats where I think this discrepency is.

When it appears to be satured (red lightning, I obtain only a -8,9dB and -7,2 dB with the Oktava 102, and only -15,9 dB with the EMU-4520…

This is the key piece that tipped me off. Those red LEDs start at -12db, and each red LED means 4db. Once I looked at your resulting values, I would assume that you're thinking each one is 1db and then all of the above values are rather close (with a wide swing in dbfs vs what you interpret those LEDs to represent). It all generally lines up once I do that. Unless there is a bit of information that I've missed, I'm thinking it's just a simple misunderstanding as to what those LEDs mean.

If you want a peak value that you can look at in your audio work station and see it peak at -4dbfs, you'll see all but the CLIP red LED light up on the 702. The lowest orange LED is -20dbfs. Now adjust your gain so you get satisfactory levels. with an mv/pa rating of under 1, you will likely turn the gain knob all the way (depending on how loud your content is). The reasoning behind this is you're sending so little signal to the recorder (where +20dbu = 0dbfs) and as a result, even adding all 67db of gain may only get you within 20db of that 0dbfs rating. So going back now that you know that the red leds mean 4db difference and that the recorder will show you how much gain you're using, I'm curious, what does it say?

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Offline DigiGal

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To DigiGal

"DigiGal" wrote: "Perhaps what you are experiencing is related to an output attenuation setting.
Especially since you bought it used if you can't get it resolved by toggling settings it would be
advisable to send it in to Sound Devices for a full checkout and/or repairs and calibration."


I've bought a a new 702, not a used one... So I don't think I need to calibrate newly the device.


R. Parejo-Coudert
Ethnomusicologist


My bad, for some reason I thought you bought a used 702.  Regardless, you wrote that Sound Devices Tech Support couldn't help you so I was ultimately offering you some observations from the manual that would help give you some things to check.  Since you bought it new then it seems doubtful that it could be a defective unit or a bad calibration of the led level meters, leaving Operator Error.  Best of luck!
Mics: AKG CK91/CK94/CK98/SE300 D-330BT | DPA 4060 4061 4266 | Neumann TLM 103 | Senn ME66/K6/K6RD MKE2 MD421 MD431 | Shure VP88 SM7B SM63L SM58 Anniversary Cables: Gotham GAC-4/1 Quad w/Neutrik EMC | Gotham GAC-2pair w/AKG MK90/3 connectors | DigiGal AES>S/PDIF cable Preamp: SD MixPre-D Recorders: SD MixPre 6 | Marantz PMD 661 Edit: 2011 27" 3.4GHz Quad i7 iMac High Sierra | 2020 13" MBA Quad i7 Catalina | Wave Editor | xACT | Transmission | FCP X 

Offline John Willett

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Since you bought it new then it seems doubtful that it could be a defective unit or a bad calibration of the led level meters

Why do you say this?

I have bought things in the past, even from top manufacturers, that have been faulty/defective from new.

That's why they are guaranteed.

It may be very rare, but it *is* possible.

Though, I do think that the suggestion about the LED dB spacing posted above seems the most likely.

Also, it does sound like the OP is trying to record too hot - it's best to use -18dBFS (-20dBFS in the USA) as the 0VU point and to peak around the -19dB point (assuming 24-bits of course).

This gives you safety headroom and you then normalise to about -2dBFS in the DAW.

Offline DigiGal

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Re: [WAS] Some recurrent problemas with my new Sound Devices 702 recorder
« Reply #10 on: June 05, 2013, 01:35:56 PM »
Since you bought it new then it seems doubtful that it could be a defective unit or a bad calibration of the led level meters

Why do you say this?

I have bought things in the past, even from top manufacturers, that have been faulty/defective from new.

That's why they are guaranteed.

It may be very rare, but it *is* possible.

Though, I do think that the suggestion about the LED dB spacing posted above seems the most likely.

Also, it does sound like the OP is trying to record too hot - it's best to use -18dBFS (-20dBFS in the USA) as the 0VU point and to peak around the -19dB point (assuming 24-bits of course).

This gives you safety headroom and you then normalise to about -2dBFS in the DAW.

Well, because the OP stated that Sound Devices couldn't help him.  If their excellent support team suspected a technical problem with a new unit surely they would have requested it be sent in to them under warranty.  I pointed out some areas for the OP to check in another message but it's unknown if he actually did.
« Last Edit: June 05, 2013, 02:09:01 PM by DigiGal »
Mics: AKG CK91/CK94/CK98/SE300 D-330BT | DPA 4060 4061 4266 | Neumann TLM 103 | Senn ME66/K6/K6RD MKE2 MD421 MD431 | Shure VP88 SM7B SM63L SM58 Anniversary Cables: Gotham GAC-4/1 Quad w/Neutrik EMC | Gotham GAC-2pair w/AKG MK90/3 connectors | DigiGal AES>S/PDIF cable Preamp: SD MixPre-D Recorders: SD MixPre 6 | Marantz PMD 661 Edit: 2011 27" 3.4GHz Quad i7 iMac High Sierra | 2020 13" MBA Quad i7 Catalina | Wave Editor | xACT | Transmission | FCP X 

 

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