Microphone recording help please

G

GeoOscar

Guest
Could somebody please advise if it is possible to use a low impedance (0.5
kohm) akai dynamic microphone ( from an old component cassette deck) with a
current generation mini hifi unit which only has AUX inputs (47kohm
impedance 500mv ?). It is only for basic voice and beginner piano student
teaching purposes, so doesn't need to be "hifi" quality recording - just for
Cassette deck playback. I realise that I would need an adaptor plug, but am
not sure if the impedance mismatch and output level would be compatible ?
Any suggestions for a low cost solution to this need would be appreciated.
Thanks. GeoOscar
 
GeoOscar <gcmurphy@optusnot.com.au> wrote in message
news:41d15128$0$1119$afc38c87@news.optusnet.com.au...
Could somebody please advise if it is possible to use a low impedance (0.5
kohm) akai dynamic microphone ( from an old component cassette deck) with
a
current generation mini hifi unit which only has AUX inputs (47kohm
impedance 500mv ?). It is only for basic voice and beginner piano
student
teaching purposes, so doesn't need to be "hifi" quality recording - just
for
Cassette deck playback. I realise that I would need an adaptor plug, but
am
not sure if the impedance mismatch and output level would be compatible ?
Any suggestions for a low cost solution to this need would be appreciated.
Thanks. GeoOscar

Neither the impedances or the level are likely to be a good match. You could
Click to expand...
correct the impedance part with a mike transformer, but that's still
probably going to leave you with too little signal, maybe around 10
milliovolts only. You really need a mike preamp, they're not hard to come by
readymade or in kit form.
 
"GeoOscar" <gcmurphy@optusnot.com.au> wrote in message
news:41d15128$0$1119$afc38c87@news.optusnet.com.au...
Could somebody please advise if it is possible to use a low impedance (0.5
kohm) akai dynamic microphone ( from an old component cassette deck) with
a
current generation mini hifi unit which only has AUX inputs (47kohm
impedance 500mv ?). It is only for basic voice and beginner piano
student
teaching purposes, so doesn't need to be "hifi" quality recording - just
for
Cassette deck playback. I realise that I would need an adaptor plug, but
am
not sure if the impedance mismatch and output level would be compatible ?
Any suggestions for a low cost solution to this need would be appreciated.
Thanks. GeoOscar
Click to expand...

The only issue you will have is that your Auxillary input to your tape deck
is designed for a Line level input of around 775mV input where your
Microphone will probably be putting out <10mV you will need some sort of
Pre-amp to boost the signal these vary from do it yourself Kits available
from Dick Smith ( www.dse.com.au ) cat no K5608 for $7:15 Cat no K5402 for
$16.99 or from Jaycar ( www.jaycar.com.au ) KC5166 for $7.95 and KC5159 for
$15:95 or AA0220 is a Prebuilt module for $15:95 (needs power ie 9V battery
and connectors).
There used to be some cheap (around $40) 4 input mixer/Pre amps around -
very ordinary but adequate for your described need but no-one seems to stock
them any more.
In the range of more expensive ready made solutions a cheap Behringer (
www.behringer.com ) mixer is probably your best bet as they are as cheap as
any other Mic pre amp as a Eurorack UB502 will set you back under $100 (rrp
$99:99 but af the music shop know you they can usually knock a few more $
off) and give you 1 Microphone input (with a tiny bit of EQ) and two Stereo
inputs .... A bit more up market gets you the Eurorack UB802 which then
gives you two Microphone Inputs with slightly more EQ for rrp $129:99.
Or if you wish to stick with the Dedicated Mic Preamp path Behringer do the
Tube Ultragain for around $100 again (but the little mixer probably offers a
bit more) ....

Impedance matching was important in the days when Active amplifiers were
rare and expensive beasts so that you needed to get as much out of the
signal you had as possible.

Most Mixing desks etc have an input impedance of at least 1.5K ohms often as
high as 3K whereas most Microphones that get connected to them have an
output impedance of 150 Ohms or so.
Nowadays (and in the situation you are describing) every stage is active and
impedance does not matter as much as once it did (Note I am talking about
Audio Frequencies here - Higher (Radio etc) Frequencies have reflection
issues etc which make impedance matching important) except in some rare
cases such as long line telephones etc and even then a modern phone deals
with all sorts of impedance mis matches.
 
Many thanks richard and bruce for your prompt and valuable advice. Just
what I needed. Will go and check out the products at DSE and Jaycar.
Cheers
GeoOscar

"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:33eamnF3qmqrqU1@individual.net...
"GeoOscar" <gcmurphy@optusnot.com.au> wrote in message
news:41d15128$0$1119$afc38c87@news.optusnet.com.au...
Could somebody please advise if it is possible to use a low impedance
(0.5
kohm) akai dynamic microphone ( from an old component cassette deck) with
a
current generation mini hifi unit which only has AUX inputs (47kohm
impedance 500mv ?). It is only for basic voice and beginner piano
student
teaching purposes, so doesn't need to be "hifi" quality recording - just
for
Cassette deck playback. I realise that I would need an adaptor plug, but
am
not sure if the impedance mismatch and output level would be compatible ?
Any suggestions for a low cost solution to this need would be
appreciated.
Thanks. GeoOscar


The only issue you will have is that your Auxillary input to your tape
deck
is designed for a Line level input of around 775mV input where your
Microphone will probably be putting out <10mV you will need some sort of
Pre-amp to boost the signal these vary from do it yourself Kits available
from Dick Smith ( www.dse.com.au ) cat no K5608 for $7:15 Cat no K5402 for
$16.99 or from Jaycar ( www.jaycar.com.au ) KC5166 for $7.95 and KC5159
for
$15:95 or AA0220 is a Prebuilt module for $15:95 (needs power ie 9V
battery
and connectors).
There used to be some cheap (around $40) 4 input mixer/Pre amps around -
very ordinary but adequate for your described need but no-one seems to
stock
them any more.
In the range of more expensive ready made solutions a cheap Behringer (
www.behringer.com ) mixer is probably your best bet as they are as cheap
as
any other Mic pre amp as a Eurorack UB502 will set you back under $100
(rrp
$99:99 but af the music shop know you they can usually knock a few more $
off) and give you 1 Microphone input (with a tiny bit of EQ) and two
Stereo
inputs .... A bit more up market gets you the Eurorack UB802 which then
gives you two Microphone Inputs with slightly more EQ for rrp $129:99.
Or if you wish to stick with the Dedicated Mic Preamp path Behringer do
the
Tube Ultragain for around $100 again (but the little mixer probably offers
a
bit more) ....

Impedance matching was important in the days when Active amplifiers were
rare and expensive beasts so that you needed to get as much out of the
signal you had as possible.

Most Mixing desks etc have an input impedance of at least 1.5K ohms often
as
high as 3K whereas most Microphones that get connected to them have an
output impedance of 150 Ohms or so.
Nowadays (and in the situation you are describing) every stage is active
and
impedance does not matter as much as once it did (Note I am talking about
Audio Frequencies here - Higher (Radio etc) Frequencies have reflection
issues etc which make impedance matching important) except in some rare
cases such as long line telephones etc and even then a modern phone deals
with all sorts of impedance mis matches.
Click to expand...
 
"GeoOscar" <gcmurphy@optusnot.com.au> wrote in message
news:41d21022$0$30483$afc38c87@news.optusnet.com.au...
Many thanks richard and bruce for your prompt and valuable advice. Just
what I needed. Will go and check out the products at DSE and Jaycar.
Cheers
GeoOscar
Click to expand...
No Problems but before you purchase one figure out the Price of connectors,
Case, Power supply etc then factor in the cost of a couple of hours Labour
added to the chance of the project never quite being finished and by the
time you get there the sub $100 price tag of the Behringer mixer is actually
quite reasonable (most music stores should be able to get one in) and
compareable in real terms.

Regards
Richard Freeman
 
Richard, advice understood, and I will tread carefully ! I have several
weeks before the need is critical.
Thanks again, GeoOscar


"Richard Freeman" <bogoff@nospam.spam> wrote in message
news:33el9iF3tr9q3U1@individual.net...
"GeoOscar" <gcmurphy@optusnot.com.au> wrote in message
news:41d21022$0$30483$afc38c87@news.optusnet.com.au...
Many thanks richard and bruce for your prompt and valuable advice. Just
what I needed. Will go and check out the products at DSE and Jaycar.
Cheers
GeoOscar

No Problems but before you purchase one figure out the Price of
connectors,
Case, Power supply etc then factor in the cost of a couple of hours Labour
added to the chance of the project never quite being finished and by the
time you get there the sub $100 price tag of the Behringer mixer is
actually
quite reasonable (most music stores should be able to get one in) and
compareable in real terms.

Regards
Richard Freeman
Click to expand...
 
"GeoOscar" <gcmurphy@optusnot.com.au> wrote in message
news:41d27acd$0$16979$afc38c87@news.optusnet.com.au...
Richard, advice understood, and I will tread carefully ! I have several
weeks before the need is critical.
Thanks again, GeoOscar
Click to expand...
No problems!
Further to my last thought ;-) the Behringer will out perform any of the
kit solutions I suggested (I know performance is not necessarily an issue)
and the EQ although admittedly rather sparse may still be of some use ....
 
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