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Old January 22nd, 2009, 04:40 PM   #1
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Zoom H2 to Electro-Voice 635A Hiss Problem

Hello everyone,

Can anyone suggest a solution to the hissing issue when connecting Electro Voice 635A via XLR-1/8" cable (custom made at Sam Ash in NYC) to Zoom H2?

When sound monitoring via H2's internal mikes, the sound is crystal clear, albeit not omni-directional, but as soon as I plug the 635A the horrible hissing starts.

I am willing to change the setup to once-and-for-all resolve this hissing problem.

Will I get hissing if I buy the Sennheiser Evolution G2 100 Series EW100ENGG2 - B and plug the EV 635A?

Does the hissing come from the microphone or signal incompatibility between the mike and the H2 recorder?


I am going on a 3-months road trip around America to film two projects, The Truth Is... (The Truth Is...) and a doc depicting youth against drugs.

Any help would truly be appreciated.
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Old January 22nd, 2009, 05:07 PM   #2
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The EV 635 does have low output but should sound Ok with the H2. Make sure your plugged into th Ext Mic in, NOT line in. Set the Mic sensitivity switch to Hi.
It's possible the cable is not wired correctly
I don't understand your logic behind using a G2 wireless with a portable recorder.
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Old January 22nd, 2009, 05:15 PM   #3
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Zoom H2 and noisy input for mic

The noisy/hiss plagued preamps on the mic line in with the Zoom H2 is a very well known limitation of this otherwise very good entry level unit. I have one and it gets used because the inbuilt mics are surprisingly good (considering the price) and it's small so I carry it around often....but don't bother trying to plug any other mic into it!!!! So, I'd suspect that might well be the issue you're having here.

Like Rick, I also have a G2 system and don't understand your logic either Renat as you would most likely use the G2's small Lav mic....but if you get a G2 system it's a very good tool for many audio projects/will serve you well.

If you Google 'Zoom H2 Forum' you'll find pages of advice about this unit and how to get the best out of it/work round it's limitations. Well worth a read. Good luck with the projects!

Edit: Adding forum link for you

http://www.2090.org/zoom/bbs/viewforum.php?f=15
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Last edited by Andy Wilkinson; January 22nd, 2009 at 05:38 PM. Reason: adding zoom forum link
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Old January 22nd, 2009, 05:53 PM   #4
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Zoom H2 with Sennheiser G2

I've used a Zoom H2 a few times with a Sennheiser EW-112PG2 wireless lav to avoid having to place the H2 on a high stand in front of the pulpit in a traditional church building. Also with the preacher wearing the wireless lav, I can monitor the recording of the sermon on the H2 from anywhere in the building.

This file started off as a WAV96kHz/24bit but has been reduced to a small mp3 for the website http://sermons.carmylechurch.co.uk/jan09/Jan18th09.mp3
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Old January 22nd, 2009, 06:06 PM   #5
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Quote:
Originally Posted by Rick Reineke View Post
The EV 635 does have low output but should sound Ok with the H2. Make sure your plugged into th Ext Mic in, NOT line in. Set the Mic sensitivity switch to Hi.
It's possible the cable is not wired correctly
I don't understand your logic behind using a G2 wireless with a portable recorder.
Thank you guys for the quick response!
Rick,
I have plugged the EV 635A to the Ext MIC In, and the MIC Gain is on "High".

I am also having suspicion that the cable wiring is the issue here. When my HOSA XLR-1/8" cable died I got this new cable custom-made at Sam Ash. Robert (worker there), initially soldered it in a way that the EV 635A recorded only left channel (Mono). I recorded a test video by plugging the EV 635A directly to my camcorder's 1/8" connection, dropped the resulting video into Premiere Pro timeline and saw that the audio is in Mono. I went back to Robert and asked him to rewire the cable the way the died HOSA cable was, two channels (left and right), though it just duplicated one channel twice. I guess I could have stayed with the initial Mono wiring approach, but I could not find a way in Premiere Pro how to turn that one channel track into two.

If I buy the Sennheiser Evolution G2 100 Series EW100ENGG2-B system and plug the EV 635A into the transmitter, will the audio be recorded in Mono or Stereo? Meaning, will I see two channel audio in the Premiere Pro timeline?

Thanks again!

@ Andy
Thank you for the kind word in regards to the road trip projects.
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Old January 23rd, 2009, 06:17 AM   #6
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Quote:
Originally Posted by Renat Zarbailov View Post
Thank you guys for the quick response!
Rick,
I have plugged the EV 635A to the Ext MIC In, and the MIC Gain is on "High".

I am also having suspicion that the cable wiring is the issue here. When my HOSA XLR-1/8" cable died I got this new cable custom-made at Sam Ash. Robert (worker there), initially soldered it in a way that the EV 635A recorded only left channel (Mono). I recorded a test video by plugging the EV 635A directly to my camcorder's 1/8" connection, dropped the resulting video into Premiere Pro timeline and saw that the audio is in Mono. I went back to Robert and asked him to rewire the cable the way the died HOSA cable was, two channels (left and right), though it just duplicated one channel twice. I guess I could have stayed with the initial Mono wiring approach, but I could not find a way in Premiere Pro how to turn that one channel track into two.

If I buy the Sennheiser Evolution G2 100 Series EW100ENGG2-B system and plug the EV 635A into the transmitter, will the audio be recorded in Mono or Stereo? Meaning, will I see two channel audio in the Premiere Pro timeline?

Thanks again!

@ Andy
Thank you for the kind word in regards to the road trip projects.
A couple of things - first a definition for clarification. Simply having something recorded on the two channels labelled "left" and "right" in your recorder does not mean the signal is stereo. You have 3 possibilities: mono, one mic signal recorded on one channel; dual-mono, a single mic signal recorded on both left and right channels; and stereo, two different signals from correlated mics recorded on left and right channel.

You said your initial wiring gave you a mono track when you imported it into Premiere ... was the track genuine mono showing only one channel in the timeline and one little speaker in the upper right-hand corner of the track information or did you have a track with two channels and the little stereo icon in the track information but signal was only present on the left channel while the right channel remained silent?

If you have a true mono track, you import it normally into Premiere and use the mixer panel pan control to have it appear equally on the left and right outputs. If you have a stereo track with one channel silent, you can fix it easily with an audio editor like Audition. If you don't have Audition, download the freeware editor Audacity. With Audacity the fix is about 3 mouse clicks. Load the file in and it will appear as a stereo track with one channel silent. Click the pulldown in the track info on the left and select "Split Stereo Track." The result is two mono tracks, one of which is silent. Convert the left track to mono with the same pulldown. Delete the empty right track and save the file. Done! Or if you wish you can duplicate the left track into the right and create a dual-mono file if you prefer that approach.

According to the H2 manual it has a "mono mix" recording setting that down-mixes the inputs to a single mono signal and records it as dual mono. Did you try that?

There are a lot of places that don't know how to properly wire an XLR to TRS mini adaptor. If you want the mono XLR to send to both left and right channels properly for dual mono, you need a cable that connects XLR pin 2 to both the tip and ring on the mini connector, XLR pin 3 to the sleeve on the mini, and XLR pin 1 and cable shield also the the TRS sleeve. This is different from the usual XLR to TRS adaptor you find on the shelf in music stores. The typical music store adaptor has pin 2 to tip, pin 3 to ring, and pin 1 to sleeve - this will give you dual mono all right but with the left and right channels inverted in phase with respect to each other. Mix it to mono later and the signal will disappear.

AFAIK the wireless receiver will output a mono signal to the recorder or camera's left channel only. The manual shows the ring on the stereo mini output connector is unconnected.
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Old January 23rd, 2009, 10:56 AM   #7
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Steve is correct, the mini-to-mini cable that comes with the G2 portable receiver is mono and would normally feed one channel. (left)
A new or modified cable could easily be made with a new stereo mini connector tying the tip and ring together.
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Old January 23rd, 2009, 11:43 AM   #8
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Quote:
will the audio be recorded in Mono or Stereo?
I used the "mono mix" setting, mainly to have the signal on both channels of the headphones for monitoring. I dumped one channel (assigned as "unused" in quicktime pro) before resampling as a mono mp3. A bit extravagant on the H2 file original size at 96kHz/24bit double mono (742 MB), but I'm using 4GB cards.
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Old January 23rd, 2009, 04:51 PM   #9
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Use the right tool for the job

The Zoom H2 is an interesting device. I don't have one, but it's on my
list, as I think it may be handy.

I have noticed that the main criticism I see of it from various sources
is that the external mic inputs are noisy. But I have not seen any
evidence from the people making that complaint that they were actually
using the external mic input the way it was intended to be used. So I
suspect it may be getting a bum rap.

From the specs at Zoom H2 I see that the external mic inputs are specified as

EXT MIC IN 1/8" stereo phone mini-jack (Plug-in powered: 2.5V,
Input impedance: 20k, Input level: -20/-30/-40dBm)

So the input is singled ended, unbalanced, high impedance. The power
is not phantom power (I actually saw a post on the Zoom forum where
someone was complaining that phantom power did not work :) ). It is
probably intended to provide power to a small electret mic similar to
the internal ones used on the zoom (and should be turned off it you are
using any other mic on this input). The gain (-40 dbm) is not very high,
but would be appropriate for the electret mics it was intended for.

The Electro Voice 635A ( 635A(B) - Electrovoice )
is a low impedance (150 ohms), balanced, dynamic microphone intended for
news gathering and similar use. Like all dynamic mics, the output is low
compared to condenser microphones, but is reasonable in its intended use
(fairly close, for voice).

One of the few remaining places in audio where we still have to actually
worry about impedance mismatches is with dynamic microphones. Impedance
mismatches will cause low levels, noise, and possibly aberrations in
frequency response.

This is a pretty bad mismatch. What is needed here is not a cable, but an
impedance matching device - and a cable.

Here is what I would use in this situation (a Shure A85F Line Matching Transformer):

Shure - A85F Line Matching Transformer

Which you might purchase from one of the sponsors here:

Shure | A85F - Microphone Matching Transformer | A85F | B&H

Or from many large music stores and audio dealers, perhaps locally since I see you need this quickly.

Note that in addition to proper matching, you get quite a lot of 'free'
gain with this device. They say 24 db, but that is probably power gain,
not voltage - what you will see in actual use will probably be closer to
10-15 db. That also represents an increase in signal to noise of that
amount, since this gain comes before the mic preamp. Do this, and I
suspect the zoom external mic inputs may not be quite as noisy as people
suppose. In some situations you may even need the mic pad on the Zoom.

Your horrible hiss should go away. :)

This is also a very useful device in other ways - for example if you
need to run a high impedance line a long distance, you can stick one of
these on each end of a (balanced) mic cable, and you now have a fully
balanced transmission line that will avoid the noise problems inherent
in long unbalanced lines. Though it is built for mic level use, I have
used these at line level many times to solve immediate problems. It
definitely works fine for normal voice use. Music with heavy bass or
very hot levels would saturate the transformers if used at line level, so I don't recommend
that.

With this, now all you will need is a commonly available cable to match a quarter inch phone plug to a 1/8 inch phone jack.

If you want two mics, you will also need a splitter - 1/8 inch stereo to two 1/8 inch mono jacks. Or to two quarter inch jacks to have one less converter cable.

This page has many useful devices that I see people asking about here:

Shure - Problem Solvers

Note there are several variants of this device which may be more
appropriate to your specific cabling situation on that page.

There are also other manufacturers that make these. I usually recommend Shure because they tend to be built like a tank. Some of mine are over forty years old and still going strong.

-Mike
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Old January 23rd, 2009, 09:51 PM   #10
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Quote:
Originally Posted by Renat Zarbailov View Post
...When my HOSA XLR-1/8" cable died I got this new cable custom-made at Sam Ash...
Actually, I did not understand, why you had to go for a custom made cable... I think, you had to buy again that same impedance matching Hosa connector:
Hosa Technology | MIT-156 Low to High Impedance | MIT-156 | B&H . I think, you will get much better S/N ratio plus you will get dual mono audio for your NLE...
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