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From: Ian Bell on 23 Jul 2010 13:31
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

Ian
From: amdx on 23 Jul 2010 13:39

"Ian Bell" <ruffrecords(a)yahoo.com> wrote in message
news:i2cjl0$o33$1(a)localhost.localdomain...
> 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
>
> Ian
What is the efficiency of a speaker with 110db SPL with 1mW input?
What is the cause of the losses?
Mike


From: GregS on 23 Jul 2010 15:11
In article <e1682$4c49d3fc$18d66057$10555(a)KNOLOGY.NET>, "amdx" <amdx(a)knology.net> wrote:
>
>"Ian Bell" <ruffrecords(a)yahoo.com> wrote in message
>news:i2cjl0$o33$1(a)localhost.localdomain...
>> 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
>>
>> Ian
> What is the efficiency of a speaker with 110db SPL with 1mW input?
>What is the cause of the losses?
> Mike
>
>

Space.

From: GregS on 23 Jul 2010 15:12
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.

From: krw on 23 Jul 2010 18:48
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.

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