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DXer
Joined: 12 Nov 2006
Posts: 145
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 Posted: Mon Feb 16, 2009 3:43 pm Post subject: |
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Some online research has revealed that balanced armature earbuds are immensely popular among a certain following of audiophiles...a fact that has since discouraged me from purchasing these or similar phones. The flat 20-20000Hz response hints at being incompatible with the objective of utmost sensitivity. Manufacturers achieve such a flat response by introducing damping (loss) into the mechanical system. My research, however, did reveal a far more suitable candidate for an efficient modern balanced armature driver. This driver is available from Digi-Key and the frequency response curve shows a prominent peak at 1KHz and 2KHz. An effective means of coupling the sound from the driver into the ear canal has yet to be devised.
73's |
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dezzertrat
Joined: 25 Nov 2008
Posts: 93
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| Posted: Mon Feb 16, 2009 8:32 pm Post subject: |
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| Rune wrote: | Exellent battradio.
So you don't think the sensitivity of the modern BA-plugs will weight up for the 1kHz response peak of the older ones?
They have after all a sensitivity of 115db the specs says. I don't know what that ''db'' really means, but if the db measure is in db/Volt, sensitivity is of course not as good if it's in db/mWatts. |
I've done a little looking at specs for headphones similar to these, and even have a pair of the more conventional looking headphones for MP3 players. Many manufacturers leave some of the information off their advertising material, but I discovered that these seem to be rated in decibels of sound pressure at 1 milliwatt of power, which I believe is the power of audio signal applied to the phones. Distance is not specified because the phones are next to or in the ear. Therefore the the audio output of the phones is measured right at the diaphragm, I believe.
I have a pair of conventional looking phones, not spark plugs, that advertise around 110 db or so output with 1 milliwatt input. They are out in the garage right now, and I don't remember the brand or model number at the moment. I've used them with my test bed regen set using an audio output transformer from an old tube stereo amplifier. The transformer is rated at about 10 watts output, and I think the primary impedance is around 8k ohms and the secondary about 4 ohms. I'm using it with 32 ohm stereo headphones connected in parallel giving about 16 ohms. Not a very good match, but that's all I have at the moment. Volume in these headphones is about half of what I'm getting with Trimm Featherweights hooked up in the plate circuit without a transformer. The Trimms have about 5k ohms DC resistance and I'm guessing the audio frequency impedance is around 15k to 20k ohms, which is a good match for tubes such as UX-199 or UX-201A. |
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Rune
Joined: 15 Jul 2007
Posts: 510
Location: Akershus, Norway
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| Posted: Mon Feb 16, 2009 11:11 pm Post subject: |
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That's a very interessting driver DX'er. I'm posting the response chart for easy viewing.
And, if we compare the chart above with corne's impedance measurments.
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Rune
Joined: 15 Jul 2007
Posts: 510
Location: Akershus, Norway
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battradio
Joined: 19 Nov 2006
Posts: 490
Location: near St. Louis MO.
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| Posted: Tue Feb 17, 2009 9:36 am Post subject: |
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Here is a link to Dynalec Soundpowered headsets and phones and elements .
http://www.dynalec.com/pdfs/spt/ind_spt.pdf
They list the part number of the elements also .
Mark |
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Rune
Joined: 15 Jul 2007
Posts: 510
Location: Akershus, Norway
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| Posted: Tue Feb 17, 2009 10:13 am Post subject: |
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Thank you for the link battradio 
Some data: http://www.dynalec.com/pdfs/spt/sptchar.pdf
I ask myself:
Could it be that the smaller Knowles elements are way more senisitive and give more for the money?
Since dynalec probably are using elements with modern materials, what about the sensitivity of the older SP-types from the 1930's and upwards? Could the sensitivity actually be pretty low on the older ones? |
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battradio
Joined: 19 Nov 2006
Posts: 490
Location: near St. Louis MO.
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| Posted: Tue Feb 17, 2009 11:05 am Post subject: |
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Hi Rune ,
I used to service sound powered phones on comercial vessels on the inland water ways in the mississipi valley .The Dynalec and USI UA1614-l are no better than the units from the 1940's . The RCA big cans are the loudest and most sensitive that I have listened to . Haven't listened to to DLR5's yet .Wonder what the price of the Knowels is and what they sound like .
Mark
Found another ballanced armature audio device .
http://starmicronics.com/components/components_pages/prod_series/rbb-04c-ps_series.html |
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Rune
Joined: 15 Jul 2007
Posts: 510
Location: Akershus, Norway
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| Posted: Tue Feb 17, 2009 11:32 am Post subject: |
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| battradio wrote: | | I used to service sound powered phones on comercial vessels on the inland water ways in the mississipi valley .The Dynalec and USI UA1614-l are no better than the units from the 1940's . The RCA big cans are the loudest and most sensitive that I have listened to . |
Thank you for your enlightenment on that
| battradio wrote: |
Wonder what the price of the Knowels is.. |
Something in the 20 to 30 dollar range per emement?
| battradio wrote: |
...and what they sound like. |
Yes me too. But can you imagine 115-120dB against 140dB and over? That must be an ocean of difference. |
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DB4IW
Joined: 16 Aug 2007
Posts: 256
Location: Wertheim/Germany - JN49ss
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| Posted: Tue Feb 17, 2009 12:06 pm Post subject: |
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In 2007, I have bought two pairs of those phones at Ebay - but not yet tested:
I think they were about 10 €/each plus shipping from UK.
_________________
73 de Fritz
--
Fritz * DB4IW * Wertheim am Main / JN49ss
SWL since 1963 * Radio amateur since 1976 |
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RadioBrazil
Joined: 15 May 2010
Posts: 1
Location: Brazil - Rio de Janeiro
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| Posted: Sat May 15, 2010 11:23 am Post subject: Sound powered earphones |
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Hi folks,
Does anyone have tried the Knowles acoustic transducer, similar to CI-22960 model?
I though, as Knowles transducers are balanced armature type, technically, using the same principle of "sound powered phones" used in boats, mines..., and with similar or may be, superior sensivity. This way, they could be better, and ligther, than the tradicional "sound powered phones", some times used with crystal radios?
Gil |
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Uberdyne
Joined: 23 May 2010
Posts: 12
Location: Raleigh, NC USA
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| Posted: Fri Jul 23, 2010 2:46 pm Post subject: |
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I think I am prepared to go ahead and order a pair of CI-22960-000 units. I was hoping I could find the high impedance BK-21604 units, but the CI-22960 seems to be available.
I will try to post if they work out.
_________________
Überdyne: An extraordinary small force.
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Uberdyne
Joined: 23 May 2010
Posts: 12
Location: Raleigh, NC USA
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| Posted: Sat Jul 31, 2010 3:11 pm Post subject: |
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Hmmm ...
I am now faced with the problem of trying to figure out how to use these tiny receivers. They are basically hearing aid receivers that have a tiny output opening that is supposed to couple to a flexible tube and a custom earpiece.
This is going to be trickier than I thought.
_________________
Überdyne: An extraordinary small force.
Kevin |
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Darryl Boyd
Joined: 08 Nov 2006
Posts: 70
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| Posted: Sat Jul 31, 2010 3:51 pm Post subject: |
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Remember, "Balanced Armature" units are not necessarily "Sound Powered" units. "Sound Powered" units are not necessarily "Balanced Armature" units.
"Balanced Armature" is a design or technology.
"Sound Powered" is a system.
And yes it actually is a technical term. The Navy still use "Sound Powered Systems" today. And it is a Term they use in all their manuals.
There are many types of designs used in Sound Powered systems. Not just Balanced Armature. Balanced Armature is however for our uses, the most efficient of the Sound Powered units.
I know it sounds a little like double talk sometimes, but Balanced Armature unit that are made these days are designed to be in "powered" units. The old Sound Powered headsets were designed to be in a non powered unit (mostly military). They had to be efficient so as to use every bit of the sound energy possible. The new stuff has the luxury of not worrying about that problem. A little waste is OK and make it cheaper to produce. Also newer units are much more interested in reproducing the sound to match the original sound as much as possible. That is the quality of the sound. We however could care less of the quality, efficiency is the key for us. If you're looking for quality, then you need to get out of crystal radios and into big powered units. Most of the time my RCA big cans headphones sound terrible while listening, but I could care less, I'm after a weak signal. If I want better sound (I'm just listening to the radio and some music) and trying to stay nostalgic, I use Baldwins or WE509's. Nice sound but less efficient.
One of these days they will come up with something better than "old school", but there is no real effort to do so right now. We are just not a big enough group to justify all that research.
Well, I hope I'm around to see it some day.
Darryl |
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