Questions Regarding XLR to 3.5mm Audio (HV30 specifically)

walked · Apr 28, 2009

Alright, so I've got questions regarding the Beachtek DXA-4, and the SGM-1X specifically, but this may apply to other discussions.

First and foremost, I've read that the SGM-1X is not a "hot" enough mic to be used without a pre-amp on the HV30. At the same time, I've read that the NTG-2 is hot enough. (just tossing that in for discussion, as the NTG-2 is a second option here).

Where I get a bit fuzzy about specific terminology / what I need precisely is with regard to power.

Both mics are battery powered so phantom power is not required (my understanding is phantom power is to electrically charge the mic for picking up sound by design, not for driving the audio).

However, as mentioned above - the SGM-1X isnt hot enough to get in without a pre-amp and have quality audio. Does the DXA-4 act as a pre-amp? Google says it doesnt require power, and I cannot find any reference that it acts as a pre-amp, yet MANY people have paired the two together. What purpose / actual reason is involved here?

Would I be better off picking up an NTG-2 + simple XLR to 3.5mm adapter, and going without the beachtek instead? I've heard samples that demonstrate both mics as being very impressive. I can also add a beachtek to the NTG-2 later as budget allows / quality requires.

Really, what I'm trying to figure out is how the DXA-4 acts as a pre-amp if its not powered, and what is actually happening. Additionally, if thats the best route to take.

In case anyone needs to know, primary purpose will be using as a boom mic indoors, and some outdoors shots.

Thanks for any insight.

Alcove Audio · Apr 28, 2009

walked said:
I've read that the SGM-1X is not a "hot" enough mic to be used without a pre-amp on the HV30.

I'm not one to trash anyones product, but the SGM-1X is a very substandard mic. Avoid it.

walked said:
However, as mentioned above - the SGM-1X isnt hot enough to get in without a pre-amp and have quality audio. Does the DXA-4 act as a pre-amp? Google says it doesnt require power, and I cannot find any reference that it acts as a pre-amp, yet MANY people have paired the two together. What purpose / actual reason is involved here?

The reason is economics, people try to get away cheaply; they buy the least expensive mic and adapter/mixer they can find without regard to the resulting (lack of) audio quality.

walked said:
Would I be better off picking up an NTG-2 + simple XLR to 3.5mm adapter, and going without the beachtek instead? I've heard samples that demonstrate both mics as being very impressive. I can also add a beachtek to the NTG-2 later as budget allows / quality requires.

The NTG-2 is an adequate mic, and yes, you would be okay using it with an XLR-to-mini pin adapter. Make sure that you replace the batteries frequently - every 30 hours or so - as low voltage can seriously degrade the sound quality. If you are shooting primarily indoors you may be better off with a non-shotgun mic like the Rode NT5-S or the Oktava MK-012 (the Oktava will require an external phantom power supply but is comparable to mics at two to three times the price). Unless used with great care shotgun mics tend to give that "roomy" echo sound when used indoors.

walked said:
Really, what I'm trying to figure out is how the DXA-4 acts as a pre-amp if its not powered, and what is actually happening. Additionally, if thats the best route to take.

Okay, most of the Beachtek adapter/mixers are passive, meaning that all they do is control the volume levels while converting XLR to 1/8" pin. Passive mixers can provide some audio gain at the price of added noise. The Beachtek DX-6 series also provide phantom power, which requires them to be powered by a 9V battery. Another option is the juicedLink; the CX-231 and CX-431 both supply phantom power. "Powered" mixers/adapters will give you more gain with less noise.

In the end, however, the quality of your sound will depend upon the talents of the person in charge of the sound. An NTG-2 ($260) in the hands of a pro will sound 1000% better than a Schoeps CMIT5U ($2000) in the hands of whichever PA isn't doing anything at the moment.

walked · Apr 28, 2009

Thank you very much for the insight.

From the sounds of it, the NTG-2 paried with the CX211 (no phantom power, but does have a pre-amp) may be a very passable option to pursue, no?

I will avoid the Azden SGM-1X per your advice (and a few others on another forum). Cant hurt to pay a bit more for quality in the long run.

Thanks.

Alcove Audio · Apr 28, 2009

The CX211 or DX4 mixer/adapters ARE NOT mic pres, they are only a passive mixers; however, I can understand your budgeting problems. As an audio guy I would much prefer to have external phantom power rather than relying on a battery in the mic, so the juicedLink CX-231 or the Beachtek DX-6 would be my recommendation.

One thing to keep in mind is that your audio investments - and many of your accessories like a tripod - will long outlast your camera if you buy quality and maintain them properly; I have and still use mics that I've owned for 25+ years.

walked · Apr 28, 2009

Alcove Audio said:
The CX211 or DX4 mixer/adapters ARE NOT mic pres, they are only a passive mixers; however, I can understand your budgeting problems. As an audio guy I would much prefer to have external phantom power rather than relying on a battery in the mic, so the juicedLink CX-231 or the Beachtek DX-6 would be my recommendation.

One thing to keep in mind is that your audio investments - and many of your accessories like a tripod - will long outlast your camera if you buy quality and maintain them properly; I have and still use mics that I've owned for 25+ years.

I am fairly positive you are incorrect on the DX211. It DOES NOT provide phantom power, I do agree there. However, every product page says its an active pre-amp, and that it requires a single 9V battery.

Low-noise preamplifier:

• 3 gain settings

• Improves camcorder signal-to-noise ratio

• Frequency Response: +/- 1dB typ, 20Hz-20kHz

• 13dB better than Beachtek DXA-2S

• Power:

• Single 9V battery (not included)

http://www.juicedlink.com/index_files/CX_camcorder_XLR_microphone_adapter_audio_mixers_CX211.htm

Am I wrong on this one?

Alcove Audio · Apr 29, 2009

There is a difference between active and passive mic pre-amps. In the production mixers or studio engineers lexicon a mic-pre is an active unit that controls and shapes the incoming mic signal, so for that reason I don't consider passive units as mic pre-amps although technically they are. Sorry for the confusion.

When you turn the volume control all the way up on a passive mic-pre you are getting the unattenuated signal (0dB) from the mic; as you turn the volume down you are attenuating the input signal. On an active mic pre the unattenuated signal is in the center (0dB) position; when turning the volume down from the center position you attenuate the incoming signal (-dB), when turning it up past the center position (unattenuated "0dB" signal) the mic-pre increases the incoming signal (+dB). To the best of my knowledge and from the documentation the CX211 does not appear to add additional gain to the mic level, so is not an active mic pre-amp.

The gain settings are pads, meaning that they reduce the incoming signal; some mics have this feature as well. "Hi" means that there is no pad, "Med" is probably a -10dB pad, "Lo" is probably a -20dB pad.

The 13dB differentiation is frequency response, not output levels.

Having powered circuitry ostensibly gives cleaner output.

Keep in mind that these are all marketing specs and stats. The specs look similar to, say, the Sound Devices 302, (which I have used and at $1300 is an industry standard) but by comparison don't hold up in the real (reel? lol!) world. That's not to say the CX211 isn't a nice little unit for the price.