JASMITH7520
Member
i have a "source" audio output rated at less than 50 ohms....My "input" is looking for 1k ohms.....In simple terms (for my boss) why doesn't it work?
50 ohms to 1k ohms
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
It should work just fine. It's good for audio singals when the source impedance is lower than the destination impedance. Voltages matter more.
There's something else wrong. Is this an earphone jack feeding an amplifier input? If so, the volume control of the source will have an effect.
More info. please?
Speedskater
Senior Member
- Location
- Cleveland, Ohio
- Occupation
- retired broadcast, audio and industrial R&D engineering
Almost all modern audio equipment is designed to work in what is called the bridge mode both at signal voltage level and loudspeaker power level. Microphone circuits are designed differently. In the bridge mode the output impedance of the source can approach 0 ohms (for loudspeakers) and the load impedance can be 100K ohms or more (for signal level). A long time ago profession equipment used matched 600 ohm input and output impedance's.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
What doesn't work about it? Those impedance are just fine (low impedance source driving a high impedance input, but not the other way). As mentioned above, levels matter, although a 10kohm input is probably consumer equipment (nominal level -20dbm*). What are the equipment and out/input level ratings?
dbi or dbm, pick your flavor. I still write dbm out of habit for audio gear.
JASMITH7520
Member
trying to set up my fire alarm panel for internet paging (Yes it's allowed by the AHJ here)
Using a Valcom VIP-801 module at the "master" and at each of the other campus'....If I connect an earbud at the output of either 1 of my "slave" modules i get clear audio but nothing is coming out over my FA speakers. Been thru the programming and such for the FA panel and I hear my amps and speakers turning on but no output....Adjusted the volume to max today and no difference.....Thought maybe there was a problem with my FA ASU (audio source unit) input and the modules output....
gadfly56
Senior Member
- Location
- New Jersey
- Occupation
- Professional Engineer, Fire & Life Safety
Which fire alarm system are you connecting to? I took a quick look at Valcom's web site, and I didn't find any UL listing for fire alarm purposes. As one "for instance", there is no mention of speaker supervision that I could find. I understand that he may have said you can do it. His approval just means another body sitting at the defendant's table if things go south.
zbang
Senior Member
- Location
- Roughly 5346 miles from Earls Court
What happens when you shoot another signal into the FA? If something is coming out of one jack,and doesn't work when connected to the other, find another source and try that. You may have a missing input module or gross level mismatch.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Have another source you can try as a test? Or another cable? Are you mixing mono and stereo?
Troubleshooting is a process of elimination. Substitution is a good first step.
JASMITH7520
Member
As it turned out
As it turned out
Thanks to all for the info...as it turned out the "EE" who designed he system left out 1 tiny little component.......The adjustable pre-amp that acts like a bridge between the low-level audio source and the 1vrms audio source input... Thanx again JASmith
As it turned out
Thanks to all for the info...as it turned out the "EE" who designed he system left out 1 tiny little component.......The adjustable pre-amp that acts like a bridge between the low-level audio source and the 1vrms audio source input... Thanx again JASmith
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