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Digital Recorders - EVP Question


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#16 CaveRat2

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Posted 24 May 2010 - 06:35 AM

The H2 is fine provided it is used in its HQ setting, preferably with external mics in order to get sufficient spacing between them for spatial analysis. About 18 to 30 inches is what I recommend. That is enough to get sufficient time differential without creating the "hole in the middle" effect.

#17 Old Guy

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Posted 24 May 2010 - 08:41 AM

Analog recorder:
1. Stereo capable.
2 Mechanical - .05% or better Wow and Flutter.
3 40 - 12,000 Hz frequency response or better.

Due to the nature of the beast, I wouldn't have thought an anolog recorder could be adequately shielded against RFI. The *better* ones <cough> do employ internal magical filters. Maybe I shouldn't be, but I'm a little surprised you can still buy them.

Being the closest thing we have to an ITL, have you peeked inside one? Do they have any internal shielding? How do they shield the tape path?

FOOTNOTE: There was a story LONG ago about someone taking a recorder aboard the Queen Mary, after she was retired to Long Beach. They the recorded the length of a tape (about an hour) without a microphone. SURPRISE! They captured EVPs. Unfortunately, John Q. Public recognized one of the EVPs as a snippet from a commercial radio broadcast.

Edited by Old Guy, 24 May 2010 - 08:44 AM.

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#18 DeadTrish

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Posted 24 May 2010 - 02:11 PM

Actually a project I'm still working on (work in progress for a couple years now) I've been working on something with an analog recorder. It's almost studio quality but it's what I have it in makes the difference...or what I WILL have it in. Basically it's own faraday box. It's just something I've been working on for a while. If something really wants to imprint a voice on the tape I would have ruled out a lot of outside interference. Whirly Dude
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#19 Old Guy

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Posted 24 May 2010 - 02:57 PM

Actually a project I'm still working on (work in progress for a couple years now) I've been working on something with an analog recorder. It's almost studio quality but it's what I have it in makes the difference...or what I WILL have it in. Basically it's own faraday box. It's just something I've been working on for a while. If something really wants to imprint a voice on the tape I would have ruled out a lot of outside interference. Whirly Dude

"Sounds" like a solid approach. If you have the physical space (not very much), you mike consider adding a simple RF detector, too.
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#20 CaveRat2

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Posted 24 May 2010 - 09:05 PM

Analog recorder:
1. Stereo capable.
2 Mechanical - .05% or better Wow and Flutter.
3 40 - 12,000 Hz frequency response or better.

Due to the nature of the beast, I wouldn't have thought an anolog recorder could be adequately shielded against RFI. The *better* ones <cough> do employ internal magical filters. Maybe I shouldn't be, but I'm a little surprised you can still buy them.

Being the closest thing we have to an ITL, have you peeked inside one? Do they have any internal shielding? How do they shield the tape path?

FOOTNOTE: There was a story LONG ago about someone taking a recorder aboard the Queen Mary, after she was retired to Long Beach. They the recorded the length of a tape (about an hour) without a microphone. SURPRISE! They captured EVPs. Unfortunately, John Q. Public recognized one of the EVPs as a snippet from a commercial radio broadcast.


Actually many of the older cassette recordes were better shielded than some of the junk coming out today. They have cut back to cut costs. There are actually several methods used to shield the tape path, however RF directly entering the tape is not a problem. Analog recording employs a split polepiece in the head. It is the field across the pole that creates the magnetic impulses, not a field radiating from outside. Thus it is only neccessary to block RF from the circuitry, not the head to prevent false audio from RF.

Another thing regarding the most common shielding problems. Both digital and tape use analog circuitry. (It's only how the program is saved that differs between them.) Both have high gain amplifiers to boost the signal from microphones. Thus both are equally susceptable to RF interference to the degree their shielding breaks down.

#21 DeadTrish

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Posted 25 May 2010 - 06:51 AM

Actually a project I'm still working on (work in progress for a couple years now) I've been working on something with an analog recorder. It's almost studio quality but it's what I have it in makes the difference...or what I WILL have it in. Basically it's own faraday box. It's just something I've been working on for a while. If something really wants to imprint a voice on the tape I would have ruled out a lot of outside interference. ;)

"Sounds" like a solid approach. If you have the physical space (not very much), you mike consider adding a simple RF detector, too.


Thanks!
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#22 Old Guy

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Posted 25 May 2010 - 10:43 AM

Here's an even simpler detector: http://www.eham.net/articles/18638

It's a variation of an electrometer: http://www.eskimo.co...r/chargdet.html
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#23 Ten301

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Posted 26 June 2010 - 01:21 PM

Exactly !

It's not that you can't get EVPs on cheap recorders. Rather it's that cheap recorders also get RF interference, intermodulation distortion, aliasing, added harmonic factors, cross talk, clipping, saturation leading to dropped / altered data, limited frequency response, higher background noise levels, and the list goes on. Then, to correct these shortcomings people turn to computer "cleaning" which further alters and corrupts the data.

So how relaiable is that supposed EVP you captured?

Better to use a reliable recorder from the start and minimize the false positives. Instead of debating brands though, set a minimum acceptable standard.

Digital Recorder:
1. 96 KBPS sample rate
2. 24 Bit A to D conversion, not 16 bit
3. Stereo capable with external mics
4. Non-lossy format (PCM or uncompressed WAV, not CELP processing)

Analog recorder:
1. Stereo capable.
2 Mechanical - .05% or better Wow and Flutter.
3 40 - 12,000 Hz frequency response or better.

There are additional specs related to noise levels, etc. which apply to all recorders, but above are the basics to consider.


CaveRat,

Would you have any recommendations as to reasonably priced microphones that would be a good match to use with the Zoom H2 for spatial analysis?

Thanks!

#24 CaveRat2

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Posted 26 June 2010 - 09:01 PM

Actually it would be difficult to recommend any specific makes / models because the characteristics would change somewhat based on the location and surroundings. Sensitivity and directionality each play a role. You can mgenerally figure mon most most moderate priced mics being satisfactory, people even have their own preferences based on certain characteristic sounds. I personally prefer condenser mics, but that isn't to say a good inductive mic wouldn't be just as good.

You mention spatial analysis. Any mic will do for that. The important thing here is spacing and that both mics have the same characteristics. Spatial analysis is based on the speed of sound and the phase relationship between each channel. Thus rather than microphones, the important factor is precise spacing between them. From this you do the math to determine what angle gives the same relationship as what you have recorded. Thus you can determine direction of the source of your EVP.

#25 Ten301

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Posted 26 June 2010 - 10:17 PM

Actually it would be difficult to recommend any specific makes / models because the characteristics would change somewhat based on the location and surroundings. Sensitivity and directionality each play a role. You can mgenerally figure mon most most moderate priced mics being satisfactory, people even have their own preferences based on certain characteristic sounds. I personally prefer condenser mics, but that isn't to say a good inductive mic wouldn't be just as good.

You mention spatial analysis. Any mic will do for that. The important thing here is spacing and that both mics have the same characteristics. Spatial analysis is based on the speed of sound and the phase relationship between each channel. Thus rather than microphones, the important factor is precise spacing between them. From this you do the math to determine what angle gives the same relationship as what you have recorded. Thus you can determine direction of the source of your EVP.


Thank you for your advice!

#26 Old Guy

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Posted 27 June 2010 - 08:01 AM

Though dated, I still find this useful:
http://www.ees.nmt.e...phone_list.html

The Panasonic elements have been replaced, but are still in the $1-2 range.
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#27 slimegoat

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Posted 03 July 2010 - 08:30 AM

Does anyone know what Brand and Model of digital recorders are used by the investigators in the following TV shows?:

1) TAPS
2) Ghost Adventures
3) Ghost Lab

Thank you.

Sincerely,

HauntedTruth


On Ghost Adventures, they use Olympus VN-4100PC digital voice recorders.


Product Information
Record over 144 hours of uninterrupted audio on the VN-4100PC then transfer files to your PC with speed and ease by way of the direct PC Link. With one simple cable connection, files can be transferred to a computer and be organized, listened to, and even emailed to friends and family. The compact design makes it functional and portable.

Key Features
Type Voice Recorder
Design Handheld
Max Recording Time Up to 144 Hours
Recording Media Digital
Voice Activate System (VAS)

Other Features
Headphone Jack
Long Play Mode
Built in Memory 256 MB
Battery Life Approx. 25 Hours

Dimensions
Width 1.54 in.
Depth 0.77 in.
Height 4 in.
Weight 2.22 oz.

Miscellaneous
UPC 050332400467
Release Date May, 2007

#28 slimegoat

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Posted 03 July 2010 - 08:39 AM

First off a good one is going to cost a little & I would not limit your self to what TV show are using. I use an Olympus DS-30, 1GB Digital Voice Recorder w/ Removable Stereo Mic. It has a great sound quality & It runs about $200.00. You can also use this thing in real time, meaning if you push record then plug in a set a headphones you can hear every thing, in real time that's going to be reviewed later. You can find that here on the equipment page/ghost-mart page or check music supply stores on the net



Yeah but have you ever actually heard an EVP real time while recording?? Just curious.

YES, only one time & another investigator heard it as well!


Correct me if I'm wrong, but if you could hear it as it happened, as opposed to only on the recording, wouldn't that be classified as a disembodied voice, and not an evp?

#29 CaveRat2

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Posted 03 July 2010 - 08:50 AM

First off a good one is going to cost a little & I would not limit your self to what TV show are using. I use an Olympus DS-30, 1GB Digital Voice Recorder w/ Removable Stereo Mic. It has a great sound quality & It runs about $200.00. You can also use this thing in real time, meaning if you push record then plug in a set a headphones you can hear every thing, in real time that's going to be reviewed later. You can find that here on the equipment page/ghost-mart page or check music supply stores on the net



Yeah but have you ever actually heard an EVP real time while recording?? Just curious.

YES, only one time & another investigator heard it as well!


Correct me if I'm wrong, but if you could hear it as it happened, as opposed to only on the recording, wouldn't that be classified as a disembodied voice, and not an evp?


That is correct as far as actually hearing the voice audibly. If you heard it directly without the use of any electronic device it would not be an EVP. Thus the term ELECTRONIC Voice Phenomena.

However listening in realtime to a recording being made, or using an audio amplifier or other electronic aid such as an EMF monitor would constitute an EVP. The reason the electronic device was required is not a factor. It could be because the sound was so weak you needed additioanl amlification to make it audible, it be because the voice was actually an EM Field. (With the exception of stray RF interference.) It might even be some unknown source. Voice from any of these heard through an electronic device would be considered an EVP.

I always monitor recordings in progress when doing EVP reserach. In fact rather than consider my work as recording EVPs, I would rather describe it as listening in realtime for EVPs with a recorder plugged in to the system just to keep a log of whatever I detect.

Edited by CaveRat, 03 July 2010 - 08:51 AM.


#30 ourobouros2k2

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Posted 15 July 2010 - 10:28 PM

Just a few thoughts as I just recently found this thread...

The H2 is a decent recorder, but it is no longer my primary. The preamps for the external mic jack are considerably noisier than the internal mics, and my H2 had a nasty habit of corrupting certain files, despite having a compatible card (formatted through the device) and the latest firmware (1.8). Never could figure out why it was happening as the card functions perfectly in other devices. Since I could no longer trust my precious audio files to this recorder, it became my backup to the Sony PCM-M10.

I cannot say enough good things about the Sony PCM-M10. The interal mics are PRIMO EM-172 capsules with 14-17db equivalent noise (depending on source). They are very quiet. Awesome sound quality. 4 gb internal memory + microSD memory slot. Up to 40 hours battery life (depending on record mode, sample rate, etc..). A large and easy to read screen, rugged feel, and simple menu operation round it out.

I don't buy into the noisy evp idea. I believe that recordings should be as clear as possible, because not until you run a good quality linear PCM recorder side by side with a cheap voice recorder, will it become apparent that the evp captured on the lesser recorders are nothing more than artifacts (poor sample rate or compression) or case handling. In fact, if I had my way, I would be running a set of shock mounted Rode NT-1A's (5db self noise) into a phantom power box and right into my recorder. Short of a 2k Sound Devices setup, that is the best I can get on a budget.

The practice of good evp collection protocols with lesser recorders still doesn't add to the validity of a supposed evp captured with them due to artifacting. With a linear pcm recorder and careful protocols, on the other hand, it does add validity to the rare evp (as compared to false positive plentiful "evp" on lesser recorders).

If this looks like a commercial for the Sony PCM-M10, what can I say? I suppose it has seduced me, lol. Right now B and H photo has them for 199 (after you add to cart they knock off a hundred from the 299 list). For only a little more than the H2 you can have a solid, well performing recorder that brings some credibility to your evidence.

Regards,
Andy
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