Welcome to the forum.
First question I’d have is: Are you just after volume or a specific tonal quality? The reason I ask is because if it’s the Hella Twin Supertone that you’ve tried, then from what I’ve read those horns are pushing up to 118db which is pretty darn loud.
To get any louder, I reckon you’d really need to look at high pressure air. I don’t think that doubling up on a DD unit will give you any higher pressure, just more air flow and then it’s up to whether the horns are even capable of consuming that extra flow to generate more noise. Even if you could up the pressure, horns like the Kleins are already quite high in pitch. Feeding more pressure into them is not only likely to damage them but will probably just make them squeal.
You might want to check with Dan from Oasis on this forum to see what an XD3000 would go like if connected straight to a set of Shocker or Rocker horns from Hornblasters for example. I know you can run air tools direct from the compressor so it might be good enough to run it without an inline storage tank. There might be too much initial delay while it spins up though (plus a huge spike in amperage)… dunno.
The other option would be to look at perhaps a small CO2 or pressure gas cylinder but there again you’re back to needing a tank of sorts.
What type of vehicle are you wanting to put this in anyway? Set of Shockers with a small 2 gallon tank has been put into the smallest of cars (and even motorbikes I think). They’re hard to beat and sure cop a whollop to the old ear drums.
I have a BMW e39 (2002) 525i wagon. I do not have any extra space in the trunk area for a tank. It is all taken by my surf gear. The attached pict shows the engine bay of a similar vehicle. The area to the screen left of the engine is where I will be installing.
That Oasis compressor looks great, but it is $1,500.
The Kleinn 6126 says it is rated at 132 db. Which is the loudest DD i’ve found so far.
Don’t pay attention to advertised db ratings. I could probably get 100db if I farted directly into a microphone.
Anyways - to your original question - I would almost think 2 whole kits would be louder that 2 compressors on 1 set of horns. The klein kits are only 70 bux.
Not a lot of people on the forums use those types of kits, but it would be cool to se what you come up with. Welcome to the forums.
I literally laughed out loud at your DB comment!!! Too freaking funny.
We to not pay attention to the (170+!) DB ratings you see unless you know the true source. For example the Nathan Airchime horns come documented from Nathan at high 140 DB/ low 150DB ratings but are measured the correct way. This test is done in an anechoic chamber at 100 PSI and microphone placed 1 meter away from the horns.
As to the original question, we do have a few set of horns that use a direct driven compressor but will probably give you similar results as the two you have already tried.
Hornblasters sells the XD3000 for less than $1500.
Air horns are very air hungry and usually require a volume of stored air, even Shockers. An Oasis XD3000 fills storage tanks and hoses faster. Small tanks give short blasts but you can do it a lot more often with an XD3000.
An Oasis compressor can run 1/2" impact for 2 or 3 seconds from a 25’ coil hose before the impact slows down. The compressor refills that hose fast enough for the impact to be ready for the next lug nut.
you could go with a set of Cadillac Horns out of 60’s 70’s 80’s and 90’s Cadillac Or Buick vehicles. There are four electric horns and you can adjust them to make them louder. You can sound like a freight train with out any compressor or tank at all cause they are electric. of course not as loud. Could check the local junk yards or try E-bay.
my grandpa had a 1988 Cadillac Fleetwood Brougham. one day while driving on the freeway someone cut him off and he hit the horn, the car swerved back into its lane. yeah these horns are pretty effective specially since I turned the tuning screw on each horn 1/2 a turn to the left to make them even louder. I did scare some people when I honked it. Then I tell them that they should hear the BIG Horn lol.
You can sound like a freight train with out any compressor or tank at all cause they are electric. 