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Newbie ?? about pre-amp and other requirements

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Scott Jensen
Newbie ?? about pre-amp and other requirements
on Oct 23, 2008 at 11:04:33 pm

Please take into account that I am relative newbie to audio. I need to purchase some equipment for on the road (hotel, car) voice over work as well as being able to integrate this equipment with my video gear. After doing some research on the internet tubes I've decided on getting a Porta Booth and Shure SM7B for voice over and possibly a Centrance Microport Pro USB preamp for recording directly to my laptop computer. I would like the ability to feed this mic into my Canon HV20 camcorder. At some later date I'd like to purchase the Red Scarlet camcorder and have the Shure SM7B work with it also.

Questions:

1. Does the Centrance provide enough gain for the Shure SM7B(60 db?)for notebook computer recording? Is it adequate for voiceover work?
2. I think I'll need some xlr to miniplug adaptor to use the Shure with my HV20 camcorder?
3. Will my camcorders handle the Shure SM7B microphone input? In other words will the camcorder know how much to preamplify the signal from the Shure mic?

4. Does the porta booth really work as advertised.

5. Is there a way to mount a MIC such as the Shure SM7B to my camcorder

Thanks!


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Rodney Morris
Re: Newbie ?? about pre-amp and other requirements
on Oct 24, 2008 at 1:54:58 pm

Hello Scott,

Let's start with a brief tutorial. A mic preamp's primary function is to take a mic level audio signal and convert into a line level audio signal. That's what it does. Because of the internal components of different mic preamps, they often impart a particular "sound" or "coloring" on the mic. That's what many pros are looking for in a mic pre is how it affects the sound to achieve the desired effect. For example, if they're looking for a nice warm, round sound they may go with a tube preamp. But again the preamp's primary function is to go from mic level to line level. The other thing that a preamp provides is phantom powering for condenser microphones. Condenser mics need some type of voltage applied for them to operate correctly. Dynamic mics do not need said voltage. So a micpre will provide phantom powering (48V is most common) for condenser mics.

You are looking at a Shure SM7B, which is a dynamic mic. It needs no powering. You also have a Canon HV20 which provides a 1/8" stereo mic level mini plug. You don't necessarily need a preamp to connect this mic to this camcorder. You DO need an adapter to go from XLR to 1/8" stereo mini. Also, if your laptop's audio input is a mic input, you don't necessarily need a preamp to get into the computer. The real question is how much control will you have over level once you get into the camcorder and computer. You should be able to adjust your levels accordingly however.

The SM7B is as big as your camcorder, so mounting it to it may be difficult.

I've never used the porta booth.

I do alot of work with reporters and correspondents in the field. Often when they need to do some audio tracking for whatever piece they are working on, they usually look for a quiet place to record (car, quiet room, etc...) and a handheld mic. For us working in TV, our handheld field mic of choice is the EV RE50. It doesn't sound big and full like a studio condenser mic (because it's a handheld dynamic mic) but it gets the job done. I don't know what your application is, but perhaps an RE50 would work for you as well. There are VERY robust, not fragile at all - which is why we field guys like them so much.

I hope this helps. Feel free to ask if anything I've mentioned is unclear. There are alot of (more) qualified audio folks here that can help.

Rodney



Freelance Sound Technician/Mixer


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Ty Ford
Re: Newbie ?? about pre-amp and other requirements
on Oct 24, 2008 at 5:13:34 pm

Hello Scott and welcome to the Cow Audio Forum

1. Does the Centrance provide enough gain for the Shure SM7B(60 db?)for notebook computer recording? Is it adequate for voiceover work?

For close micing VO work, yes. I ran a MicPort Pro here with a sennheiser 421. They are similarly sensitive. Here's my published review.
http://www.dv.com/reviews/reviews_item.php?articleId=196604261

2. I think I'll need some xlr to miniplug adaptor to use the Shure with my HV20 camcorder?

A standard female XLR to 1/8" TRS will not work. You need a special female XLR to male 1/8" TRS cable. You need one that puts the mic signal to both tip and ring. You want this one:
http://www.trewaudio.com/store/product.php?productid=146&cat=21&page=1

3. Will my camcorders handle the Shure SM7B microphone input? In other words will the camcorder know how much to preamplify the signal from the Shure mic?

The question is whether the HV20 mic preamp has enough quiet gain to do the job. No one can tell you that until you try it.

4. Does the porta booth really work as advertised.

There are several of these contraptions on the market. They may help to a degree, but nothing takes the place of a proper recording environment.

5. Is there a way to mount a MIC such as the Shure SM7B to my camcorder "

Rube Goldberg makes a mount :), but the SM7B is designed to work at a distance of 4 to 6 inches. Mounting it on a camera would not be a good application.

Regards,

Ty Ford



Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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David Jones
Re: Newbie ?? about pre-amp and other requirements
on Oct 24, 2008 at 6:03:16 pm

Hi Scott-

One other alturnative you might look at is the Coles Lip Mic. Network news reporters use them to voice their packages. I've used them at a TV station I worked at that had them in their live trucks. They cut out background noise, and give you a near studio sound! They're not cheap (around $800) but you won't have to buy that porta booth.

Dave


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Scott Jensen
Re: Newbie ?? about pre-amp and other requirements
on Oct 24, 2008 at 9:13:43 pm

Thanks so much for your input. After reading your post and further research on the net I've learned the Canon HV20 really needs a preamp and the Juicedlink cx231 seems to be whats needed.

Since the Juicedlink provides phantom power it could potentially be used with a high quality studio condenser mics (Rode nt1a) for recording to the camcorder. Yes?

I guess my goal in wanting to record everything to HDV tape is to eliminate one piece of equipment (the Centrance preamp). And archiving to tape is a benefit over hard drive.

Question:

1. Is the HDV audio recording specification sufficient to record VO say with the Juicedlink and the Rode nt1a? In other words is the HDV tape a limiting factor?

I see the specs for the Centrance are 24 bit @ 96khz.
I can't find the specs for the Canon HV20 audio bit depth and sample rate.



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Ty Ford
Re: Newbie ?? about pre-amp and other requirements
on Oct 24, 2008 at 10:17:56 pm

"Thanks so much for your input. After reading your post and further research on the net I've learned the Canon HV20 really needs a preamp and the Juicedlink cx231 seems to be whats needed.

>>>Scott, my own preference, although it costs more would be for a Sound Devices 302.
http://www.sounddevices.com/products/302master.htm
Much better design and one that will provide years of service. Don't think of it in "camera years", where the camera will be out of date in 18 months, or less. Good audio gear has a MUCH longer usable life.

Since the Juicedlink provides phantom power it could potentially be used with a high quality studio condenser mics (Rode nt1a) for recording to the camcorder. Yes?

>>>Yes. The Rode NT1a is an OK studio mic, but I don't consider it a high quality condenser mic. What you you want to record with it?

I guess my goal in wanting to record everything to HDV tape is to eliminate one piece of equipment (the Centrance preamp). And archiving to tape is a benefit over hard drive.

Question:

1. Is the HDV audio recording specification sufficient to record VO say with the Juicedlink and the Rode nt1a? In other words is the HDV tape a limiting factor?

>>>The audio spec for HDV is limited to 384 kbps stereo MPEG; about 1/5 the data of even a CD. That's one of the reasons I lagged back and bought a Canon XL2 4 years ago. The audio was just not up to snuff. Regardless of that, some people use HDV audio.

I see the specs for the Centrance are 24 bit @ 96khz.
I can't find the specs for the Canon HV20 audio bit depth and sample rate

>>> BRB.....from the Canon site.
DV: 16 bit (2ch) 48 kHz
12 bit (4ch) 32 kHz
4ch synchronous recording not possible
HDV: MPEG1 Audio Layer II (2 ch)

The above specs form the Canon site confirm that HDV audio is MPEG 1 Layer II. Curiously, It does not specify the data rate. I think you will find that the data rate is as I quoted 384 kbps stereo.

Also note that the DV audio rate is shown as 16-bit 48 kHz; slightly better than CD, but dependent on how well the audio section is designed. Because the audio input is unbalanced, you're starting out with a liability.

Some years back when the first Sony HDV cameras came out, I called Sony and spoke to one of their engineers about the MPEG audio. In a technical world in which specs are supposed to get better and better, why would anyone want a spec that was 1/5 the data rate of CDs!?

The HDV format is a collection of data compression compromises, both audio and video. They (not just Sony, but whomever was involved with the spec, Sony included) chose to rob Peter to pay Paul. They needed as much technical space as possible to achieve the video they wanted, so they skrimped the space from the audio.

There were also latency issues. Data compression results in latency (delay). In order to have the picture and sound sync up properly, delay had to be added to the audio to sync it to the highly compressed, delayed video. Arguably, one way to do this would be to data compress the audio to a point that would delay the audio so that it would sync to the compressed HDV video. And there you have it!

The Sony rep agreed with me that, if really good audio is what you want, you need to double record. That is, record audio separately on a system with a higher quality audio spec.

Have a great weekend,

Regards,

Ty Ford



Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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Scott Jensen
Re: Newbie ?? about pre-amp and other requirements
on Oct 26, 2008 at 11:19:54 pm

After further research I'll probably be getting a Sennheiser MKH 416 that'll work for now and should match

the quality of the someday to be unleashed Red Scarlet. Based on the MP3 recordings of the Sennheiser I've heard it sounds great.

Some forum indicated that the Red One does better with a line level input, I'm guessing because thats

because the internal camcorder preamp gets bypassed? Assuming (big assumption) that the Red

Scarlet has similar audio recording capablities, I should look for a preamp with line level ouptut...

1. Do all standalone preamps put out line level signal?
2. What is the port/connector/cable called that uses line level signal
3. Is there a standalone preamp that puts out both line level signal and a usb signal?

I couldn't find one that does both.

I know you recommended the Sound devices 302, but its kinda expensive...

4. Is there a preamp with usb and line level signal output that matches the quality of the Sennheiser MKH 416 that
does both USB and line level signal output? Preferably one under $500.


5. If I am recording to my notebook (with the previosly mentioned recording equipment) and am listening to the recording (after capture) via analog headphones
will I be hearing the full quality?

I'm guessing no.

6. The digital to analog conversion in the notebook is bad?

7. Is there a digital headphone that when used with my notebook would represent the recorded signal? Make, Model?

8.I am guessing the bit depth, and freq. response of the digital hardware are not so good in the notebook?


Thanks so much!






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Ty Ford
Re: Newbie ?? about pre-amp and other requirements
on Oct 27, 2008 at 12:13:41 am

[Scott Jensen] "After further research I'll probably be getting a Sennheiser MKH 416 that'll work for now and should match

the quality of the someday to be unleashed Red Scarlet. Based on the MP3 recordings of the Sennheiser I've heard it sounds great.

Some forum indicated that the Red One does better with a line level input, I'm guessing because thats

because the internal camcorder preamp gets bypassed? Assuming (big assumption) that the Red

Scarlet has similar audio recording capablities, I should look for a preamp with line level ouptut...

>>>The difficult part is making a mic preamp in a camera that doesn't pickup noise from other camera parts. The current RED has low level noise problems and some new boards are being sent to some people. That's what I heard last week down in DC from a RED owner.

1. Do all standalone preamps put out line level signal?
>Pretty much. That's what a preamp does.
2. What is the port/connector/cable called that uses line level signal
>The "plumbing" varies by make and model. XLR, 1/4" TRS are the usual.
3. Is there a standalone preamp that puts out both line level signal and a usb signal?

I couldn't find one that does both.
>http://www.sounddevices.com/products/usbpremaster.htm

I know you recommended the Sound devices 302, but its kinda expensive...

4. Is there a preamp with usb and line level signal output that matches the quality of the Sennheiser MKH 416 that
does both USB and line level signal output? Preferably one under $500.
>http://www.sounddevices.com/products/usbpremaster.htm


5. If I am recording to my notebook (with the previosly mentioned recording equipment) and am listening to the recording (after capture) via analog headphones
will I be hearing the full quality?

I'm guessing no.
> Depends on how good your headphones and headphone amps are.

6. The digital to analog conversion in the notebook is bad?
>Compared to what? Listen and find out.

7. Is there a digital headphone that when used with my notebook would represent the recorded signal? Make, Model?
>At some point the audio has to be converted to analog so you can hear it, as such, there really aren't any digital headphones unless they have a built in D/A converter. I haven't seen any yet.

8.I am guessing the bit depth, and freq. response of the digital hardware are not so good in the notebook? "
>Compared to what? The converters in my Mac Ti book were really better than I expected.

Regards,

Ty Ford



Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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Scott Jensen
Re: Newbie ?? about pre-amp and other requirements
on Oct 27, 2008 at 3:46:41 am

Thanks for your patience sticking with this thread. I could probably pop down to the (not so) local music shop and have these questions answered but would be $20 poorer from buying gas.

I looked at the preamp

http://www.sounddevices.com/products/usbpremaster.htm

but couldn't download Adobe Reader, to read the PDF on it.

Questions:

1. If I feed two separate signals into the xlr inputs of the Sound Devices preamp will it output two separate channels (tracks?) of audio simultaneously via the USB?

2. Will Adobe Premiere recognize it as two tracks and not one mixed track.

If not

3. How can the other Sound Devices digital outputs (ports marked S/PDIF, PC audio) be captured onto my notebook? Some sort of adapter? My notebook only has firewire and USB and the analog MIC input.

4. I don't think two separate digital streams can be captured by a notebook?







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Ty Ford
Re: Newbie ?? about pre-amp and other requirements
on Oct 27, 2008 at 10:47:46 am

[Scott Jensen] "I looked at the preamp

http://www.sounddevices.com/products/usbpremaster.htm

but couldn't download Adobe Reader, to read the PDF on it.

>>Can't help you there.

Questions:

1. If I feed two separate signals into the xlr inputs of the Sound Devices preamp will it output two separate channels (tracks?) of audio simultaneously via the USB?

>>Yes

2. Will Adobe Premiere recognize it as two tracks and not one mixed track.

>>That depends on your computer and on Premiere.

If not

3. How can the other Sound Devices digital outputs (ports marked S/PDIF, PC audio) be captured onto my notebook? Some sort of adapter? My notebook only has firewire and USB and the analog MIC input.

>>Unless your computer sound card has S/PDIF ports, you can't use S/PDIF. I don't know what PC audio refers to. Call SOund Devices today and tell them what you want to do. See what tey say.

4. I don't think two separate digital streams can be captured by a notebook? "

>>Two streams? as in from two physical connectors? Not without a hardware interface of some sort.

Regards,

Ty Ford



Want better production audio?: Ty Ford's Audio Bootcamp Field Guide






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