120 Ohm Speaker - Electronic Circuits Projects Diagrams Free

Manu · 26th May 2003, 05:36 AM

Anyone know how much a 120 Ohm Speaker costs?

Sebi · 26th May 2003, 03:32 PM

I've never seen a loudspeaker with higher impedance as 50ohm.
The 100V line amplifier output impedance is 120ohm, but need a matching transformer for each loudspeaker.

Manu · 27th May 2003, 12:58 AM

Do you think adding audio transformers with 8 ohm speakers is a good solution?

The following circuit: http://www.uoguelph.ca/~antoon/circ/intercom.html

I only have 16 ohm speakers.

Sebi · 27th May 2003, 06:03 AM

In this case no need transformer. Try out with 16ohm speakers. The cause of hi-ohms speaker requirement: in microphone mode produced more signal.

Gene · 27th May 2003, 11:13 PM

The problem with a 2-way, hands free intercom is that the speaker also must act as a microphone without feeding back on itself. Normally the best is between 8 ohms and 120 ohms. Commercial intercoms operate in the 45 ohm range. This seems to allow the speaker to act (somewhat) as a microphone and speaker without too much distortion. If you did a search for "speakers 45 ohm" you will find some suppliers like:

http://www.surplussales.com/Micropho...roAudio-7.html

This is one possibility.

Manu · 28th May 2003, 04:42 AM

Quote:

Originally Posted by Sebi

In this case no need transformer. Try out with 16ohm speakers. The cause of hi-ohms speaker requirement: in microphone mode produced more signal.

I tried it with 16ohm, wasn't that bad. Well, I am just gonna look around. and stick with 16ohm for the moment.

Thanks for replying guys. It helped alot.

Madmartin · 30th May 2003, 10:59 PM

Maybe you give a try to two telephones speakers.
(the old-style type with a mechanical dial)
I think I remember them to have resistances as high as 500 ohms

Sebi · 31st May 2003, 06:07 AM

The phone is good idea, but as i remember the old telephone with dial contain 75ohm speaker with steel-membrane. The Taiwan-junk wall phone contain often 50ohm speaker, and (here in Europe) the door-phone systems working with 50ohm (plastic-membrane) speakers.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

26th May 2003, 05:36 AM	(permalink (permalink))
Manu	120 Ohm Speaker Anyone know how much a 120 Ohm Speaker costs? __________________ I am more afraid of an army of 100 sheeps led by a lion than an army of 100 lions led by a sheep Charles-Maurice de Talleyrand

26th May 2003, 03:32 PM	(permalink (permalink))
Sebi	I've never seen a loudspeaker with higher impedance as 50ohm. The 100V line amplifier output impedance is 120ohm, but need a matching transformer for each loudspeaker.

27th May 2003, 12:58 AM	(permalink (permalink))
Manu	Do you think adding audio transformers with 8 ohm speakers is a good solution? The following circuit: http://www.uoguelph.ca/~antoon/circ/intercom.html I only have 16 ohm speakers. __________________ I am more afraid of an army of 100 sheeps led by a lion than an army of 100 lions led by a sheep Charles-Maurice de Talleyrand

27th May 2003, 06:03 AM	(permalink (permalink))
Sebi	In this case no need transformer. Try out with 16ohm speakers. The cause of hi-ohms speaker requirement: in microphone mode produced more signal.

27th May 2003, 11:13 PM	(permalink (permalink))
Gene	The problem with a 2-way, hands free intercom is that the speaker also must act as a microphone without feeding back on itself. Normally the best is between 8 ohms and 120 ohms. Commercial intercoms operate in the 45 ohm range. This seems to allow the speaker to act (somewhat) as a microphone and speaker without too much distortion. If you did a search for "speakers 45 ohm" you will find some suppliers like: http://www.surplussales.com/Micropho...roAudio-7.html This is one possibility.

30th May 2003, 10:59 PM	(permalink (permalink))
Madmartin	Maybe you give a try to two telephones speakers. (the old-style type with a mechanical dial) I think I remember them to have resistances as high as 500 ohms

31st May 2003, 06:07 AM	(permalink (permalink))
Sebi	The phone is good idea, but as i remember the old telephone with dial contain 75ohm speaker with steel-membrane. The Taiwan-junk wall phone contain often 50ohm speaker, and (here in Europe) the door-phone systems working with 50ohm (plastic-membrane) speakers.