Building better High sensitivity headphones
in [Design]
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From: Ian Bell on 29 Jul 2010 11:08 GregS wrote: > In article<i2cjl0$o33$1(a)localhost.localdomain>, Ian Bell<ruffrecords(a)yahoo.com> wrote: >> amdx wrote: >>> Hi Guys, >>> I'm interested in a discussion about building a high sensitivity set of >>> headphones. >>> The intended use would with a crystal radio. >>> The usual thing is to find an old set of Brandes headphones with 2000 ohms >>> DC resistance. >>> It seems like the collective intellect here could design or modify >>> existing headphones >>> to provide a better impedance match and increase the sensitivity of >>> headphones. >>> Maybe there are some better materials now then there were 80 years ago. >>> Any ideas about the ideal characteristics for a set of crystal radio >>> headphones? >>> >> >> The sensitivity depends only on the electromagnetic circuit of the >> phones so you will not be able to make one that is 'more sensitive' than >> any currently available i.e. circa 110dB SPL per mW input. Your only >> real option is a transformer to match current ones to the crystal set. >> >> Cheers > > > I though crystal headphones were efficient. > Show me some specs to back that up. Cheers Ian
From: Ian Bell on 29 Jul 2010 11:08 krw(a)att.bizzzzzzzzzzzz wrote: > On Fri, 23 Jul 2010 18:31:21 +0100, Ian Bell<ruffrecords(a)yahoo.com> wrote: > >> amdx wrote: >>> Hi Guys, >>> I'm interested in a discussion about building a high sensitivity set of >>> headphones. >>> The intended use would with a crystal radio. >>> The usual thing is to find an old set of Brandes headphones with 2000 ohms >>> DC resistance. >>> It seems like the collective intellect here could design or modify >>> existing headphones >>> to provide a better impedance match and increase the sensitivity of >>> headphones. >>> Maybe there are some better materials now then there were 80 years ago. >>> Any ideas about the ideal characteristics for a set of crystal radio >>> headphones? >>> >> >> The sensitivity depends only on the electromagnetic circuit of the >> phones so you will not be able to make one that is 'more sensitive' than >> any currently available i.e. circa 110dB SPL per mW input. Your only >> real option is a transformer to match current ones to the crystal set. > > That makes sense. Professional headsets tend to spec 100dBA/mW. > Yup, and the audiophile ones come in around 90dBA/mW Cheers Ian
From: GregS on 29 Jul 2010 11:21 In article <i2s5gi$pvb$2(a)localhost.localdomain>, Ian Bell <ruffrecords(a)yahoo.com> wrote: >GregS wrote: >> In article<i2cjl0$o33$1(a)localhost.localdomain>, Ian > Bell<ruffrecords(a)yahoo.com> wrote: >>> amdx wrote: >>>> Hi Guys, >>>> I'm interested in a discussion about building a high sensitivity set of >>>> headphones. >>>> The intended use would with a crystal radio. >>>> The usual thing is to find an old set of Brandes headphones with 2000 ohms >>>> DC resistance. >>>> It seems like the collective intellect here could design or modify >>>> existing headphones >>>> to provide a better impedance match and increase the sensitivity of >>>> headphones. >>>> Maybe there are some better materials now then there were 80 years ago. >>>> Any ideas about the ideal characteristics for a set of crystal radio >>>> headphones? >>>> >>> >>> The sensitivity depends only on the electromagnetic circuit of the >>> phones so you will not be able to make one that is 'more sensitive' than >>> any currently available i.e. circa 110dB SPL per mW input. Your only >>> real option is a transformer to match current ones to the crystal set. >>> >>> Cheers >> >> >> I though crystal headphones were efficient. >> > >Show me some specs to back that up. Only that its pure capacitive, and small at that. Very little energy required to drive. greg
From: Ian Bell on 29 Jul 2010 18:22
GregS wrote: > In article<i2s5gi$pvb$2(a)localhost.localdomain>, Ian Bell<ruffrecords(a)yahoo.com> wrote: >> GregS wrote: >>> In article<i2cjl0$o33$1(a)localhost.localdomain>, Ian >> Bell<ruffrecords(a)yahoo.com> wrote: >>>> amdx wrote: >>>>> Hi Guys, >>>>> I'm interested in a discussion about building a high sensitivity set of >>>>> headphones. >>>>> The intended use would with a crystal radio. >>>>> The usual thing is to find an old set of Brandes headphones with 2000 ohms >>>>> DC resistance. >>>>> It seems like the collective intellect here could design or modify >>>>> existing headphones >>>>> to provide a better impedance match and increase the sensitivity of >>>>> headphones. >>>>> Maybe there are some better materials now then there were 80 years ago. >>>>> Any ideas about the ideal characteristics for a set of crystal radio >>>>> headphones? >>>>> >>>> >>>> The sensitivity depends only on the electromagnetic circuit of the >>>> phones so you will not be able to make one that is 'more sensitive' than >>>> any currently available i.e. circa 110dB SPL per mW input. Your only >>>> real option is a transformer to match current ones to the crystal set. >>>> >>>> Cheers >>> >>> >>> I though crystal headphones were efficient. >>> >> >> Show me some specs to back that up. > > > Only that its pure capacitive, and small at that. Very > little energy required to drive. > > greg That says nothing about efficiency. The only way real power can be transferred is into the resistive part of the device. The fact that it is 'largely capacitive' says nothing about the energy required to drive it. Cheers Ian |