Before I buy new/louder horns for my 1999 Bassa I wanted to know if I add a relay with wires direct to the battery terminals to the stock horns, will the better connections make them significantly louder? Loud enough? Do I really need to buy new horns?
So I tested the horns using a free dB metering phone app from 10" and 14' away, first using the stock setup and then using wires direct to the battery terminals. For grins I also tested reversing the polarity to the horn terminals. My Bassa's left horn is the high tone horn. Low is on the right.
Battery
It was on a charger during this test since the horns draw a surprising amount of current. I didn't want test results to vary depending on battery voltage. Voltage readings were above 13 volts. I figure your battery will probably be charging most times you use your horn while riding.
Polarity
Original polarity was hot wires to inside connectors. Reverse polarity readings showed less than one decibel difference in loudness, so caring about this seems a wash unless there's some phase advantage that would require more testing.
Relay
To simulate using a relay without having installed one yet, I just used stout test cables with alligator clip ends to go from the battery terminals to horn terminals. I read this somewhere:
"Maximum allowable voltage drop for any relay or switch contact is 300mV (.300V)." So the Direct db values may be a bit smaller in real world use.
I didn't have the stuff to make jumper cables to test the direct wiring with both horns on simultaneously. But based on the individual results, looks like combined they'd be significantly louder.
All readings are measured in decibels.
TESTS INSIDE GARAGE
from 10" away | from 14' away
-------------------------------------------------------
Stock | Direct | dB chg | Stock | Direct | dB chg
Both: 114.8 | | | 99.8 | |
Left: 116.9 | 117.2 | +0.3 | 102.6 | 117.1 | +14.5
Right: 108.4 | 115.1 | +6.7 | 87.0 | 108.4 | +21.4Initially I did these tests in my garage with the doors closed. It's echo-y in there. I should have done all these test outdoors. So I did more tests to tell how fewer decibels there were outside than in the garage. No difference in 10" away, but 14' away:
OUTDOOR TESTS with stock wiring from 14' away
In garage | Outdoors | dB change from in garage
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Both: 99.8 | 92.7 | -7.1
Left: 102.6 | 92.4 | -10.2
Right: 87.0 | 82.1 | -4.9End result, my horns make 92.7 dB in real life situations. I haven't found how advertised horn volumes are tested. Seems to me, outdoors from maybe a 30-50 foot distance would make the most sense. I suspect modern, louder horns rated at 120+ dB are much louder than mine.
Next up, same test on my stock headlight with a light meter app.
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