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Old August 31st, 2007, 07:00 AM   #1
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Ohms & Headphone

I'm sure many people on here, specialy camera guys will ask this question at some point. I'm currently looking into getting myself Beyerdynamic DT150 headphones, specs can be found here.

http://www.iheadphones.co.uk/headpho...amic+DT150.htm

I wish to use them with my Sony DSR370 DVCAM camera whilst on location filming action sports by myself (no audio guy). Locations can be noisy and very windy when filming power kites. So a closed cup headphones that drops the ambient noise would be great and at the same time produce a fairly load level of volume to override any remaining ambient noise.

They would also double up for my post production/studio work, so an excellent frequence responce is also required.

My question is what roll does Ohms play regarding the volume level. Does the higher the Ohms mean more resistance and thus a headphone amp maybe required or does it mean the headphones will kickout a thumbing tune??

Do I match the output from the camera?

The output from the camera, according to the Sony manual is: minijack -8 (infinite) to -15.5dBu Variable, 8 ohms.

Cheers for reading & any helps is welcome

Mark
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Old August 31st, 2007, 04:24 PM   #2
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an amplifier is delivering a standard electrical signal only under know conditions. one of these is the impedance (Ohms) of the device attached to it.
since power output is directly related to impedance, you can expect an headphone with higher impedance requiring to turn the volum louder than with a low impedance headphone. If your amplifier as the room to manage this, there is no problem, but for headphone output this could be a problem. That depends too of yield of the headphone.
Not all headphone are giving the same sound pressure (dB) for each mWatt they receive.
from the point of view of fidelity of sound, i do not think that going from 4 to 8 Ohms would change noticeably.
I am afraid that the only way to know is to try.
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Old September 1st, 2007, 01:10 PM   #3
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From a technical point of view:

For any power suppy (or amplifier) to supply maximium power, the impedence of the power supply should match the impedence of the load (the headphones).

From a practical point of view:

It is difficult to know the impedence of the headphone amplifier. Most any common (low impedence) headphone, will work properly. I doubt that you would be able to tell the difference. Other factors, such as the sensitivity of the headphones, play a much larger factor.
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Old September 5th, 2007, 09:51 AM   #4
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Thanks guys for your advice. Will post later on my final choice of headphones and results.
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Old September 5th, 2007, 10:08 AM   #5
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I don't know anything about the 370, but on the Z1 some people have had a problem getting high enough volume levels from their headphones due to their impedance. See the following:

http://www.dvinfo.net/conf/showthread.php?t=84451
http://www.dvinfo.net/conf/showthread.php?t=76602
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Old September 7th, 2007, 05:54 PM   #6
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If you're looking for good sound and durability with high sensitivity, the Sony MDR7506 can not be beat.

Regards,

TyFord
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Old September 9th, 2007, 08:18 PM   #7
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The Sennheiser HD25 headphones are pretty much the pro standard for field recording - at least with news crews. Superb response, closed cup (good isolation) and excellent sensitivity.
Whether they 'beat' the Sony MDR 7506? - You'd really have to try both, and make your own mind up!
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Old September 9th, 2007, 09:46 PM   #8
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Hello Roger,

Maybe the HD25 on your side of the pond, but in the US, MDR7506.

Regards,

Ty Ford

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Old October 6th, 2007, 08:56 PM   #9
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The ohms rules

Coming from a recording studio back ground I can tell you that impedance (ohms) absolutely do make a difference in volume output, especialy when it comes to headphones. most consumer grade headphones made today (yes even the Sonys are considered consumer)fall in that low impedance category 8 to 32 ohms. these are designed for for use with a single source. more professional headphones are usually 600 ohms, because they are designed to be connected to powerful headphone amps used in recording studios. the higher the impedance means just what the word implies, unfortunately most prosumer cameras are only equipped to drive low impedance headphones and lack the umph to drive the 600 ohms ones. to match am amplifier to the load you can allways go up (with a loss of output) but you must never go down (overdrives the amplifier ,getting closer to a direct short) . if its within your means look into the small battery powered headphone amps available on e-bay, or if youre a DIYer the plans for these are available on line and can be built if youre handy with soldering iron. either way the small amp will improve the sonic experience of ANY headphones as well as allowing you to use whatever headphones you like.
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Old October 7th, 2007, 01:53 PM   #10
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For what it's worth, I seen Ty recommend the MDR-7506s several times and on several different threads here. So I finally went out to the local music shop, that also has quite a bit of DJ gear and gave them a whirl. After listening to about a dozen different headphones there on the demo stand, I found that the 7506 was the best for the money. In my opinion there wasn't anything that was close in price that produced better sound.

In fact, the only ones on the stand that I thought had better sound were the Sony MDR-7509 HD. But at twice the price (about $200), I couldn't justify the extra expense for what I do (mainly doc work off of an XL2 right now).

Just my two bits... I like'em, and I would recommend givin' them a listen...

Kevin
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Old October 8th, 2007, 09:28 AM   #11
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Mdr 7506

These are great headphones, they collapse into small ball (sometimes thats good sometimes its bad) they are efficient and have a single point cable coming off one side only, unfortunately this can be a bad thing. About 10 or so years ago I managed a music store and these headphones had a high rate of failure in the ear cup that did not have the cable to it. I personally have a set that is 10 years old and still working. they give you a fairly good isolation but more importantly they sound like what people like to hear. are they accurate... somewhat..but for less than 100 bucks , there is nothing out here to match them. except the AKG K240 but those are 600ohms and are semi open headphones which are not as bassy but technically more accurate and extremely comfortable to wear for hours on end, but you gotta have a beefy headphone amp to use these. AKG also makes the K270 a little more expensive but are available in low impedance, and sound a little more bassy than the 240's, if you can swing it get the Beyer DT770, these are heavenly to wear and sound great, not to mention they give excellent isolation.
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Old October 9th, 2007, 04:56 PM   #12
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Quote:
Originally Posted by Kevin Randolph View Post
For what it's worth, I seen Ty recommend the MDR-7506s several times and on several different threads here.
That's exactly the reason why i ordered these headphones. Just received them today and really like them so far. The main reason was that i didn't get enough volume with some other headphones in combination with my VX2100. That problem is solved now easily.
The 7506 are smaller than i thought, but fit like a glove.

The only downside is that the price in europe is more than twice the price of the u.s. price
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