Help Tuning horns

Hi guys (and gals), this is my first post here and I need some help tuning my horns. I had this same setup on my ranger for about a year and they were loud and sounded great. I swapped them over to my F150 and they have never been the same.

I have two Grover horns that are each 29.5" long. My tank is set with a pressure switch that keeps it between 165-200 psi. Off one of the ports I have a pressure regulator that is set at 135 psi. From there I have a solenoid valve that runs both horns. After the valve it tees off to two 1/4" O.D. hoses that are the same length that goes to each horn.

I have played with tuning the horns and just can’t get them to sound right like they did on my ranger (which also had one valve teed to two 1/4" hoses) which was running at 150 psi.

I will try to get an audio or video clip up here sometime tonight. Any help is very appreciated.

Click the pic above to hear the horns.

At the beginning you can hear air going through the horns, but not honking them. Towards the end it is starting to honk them, but no where near as loud as they were when they were on my ranger.


I’m not familiar with those horns, but are you able to open the back of them to inspect the diaphragms? Sounds like either the diaphragms are messed up or air is escaping somewhere and you aren’t getting a high enough pressure. Or maybe the valve isn’t opening all the way.

BTW - welcome to the forum!


I cleaned the diaphragms a few months ago and they looked fine to me. I have been trying to get these horns set up right on the F150 for about 5 months. What kind of wear should I look for on the diaphragms? they were smooth, but not completely flat. They had a little bowl shape to them when laid on table. Anyone know where I could get new diaphragms for these and what to expect cost-wise?

You are most likely killing them at the pressure you are blowing them at. Grover max out at 100psi. Any ways to tune them you have adjust the back cap. the horns bell screws in and out to tune.

Good luck,


I know how to tune them, I have just been having trouble getting them to make good sound at all.

What pressure should I be running them at? Like i said in my original post, I was running them at 150 psi for a few years and they were really loud and sounded great. I think I read on here in a few places that 120-130 psi is best for Grovers since that is what most semis run them at. Is this incorrect?

Thanks for the help BTW.