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I'm looking for advice on designing a system for a 1932 Ford Roadster. The challenge is that the speakers should either be stealth or completely hidden.

My goal is to design the interior without any modern influences and to have a system with acceptable SQ in an open air environment (top off at 80 MPH). The project is a frame off restoration and the car is completely disassembled, so there are a lot of options for the installation.

The links below show a couple of generic examples of the dash and interior. There is very little room in the doors and no room for kick panels.






My current idea is to mount tweeters in the dash, hidden behind air vents that have a similar size as the gauges in the dash. Then, mount midrange drivers under the dash and firing down to the floor. Of course, this creates off axis issues and it is not aligned with the tweeters.

Another option may be to mount the midrange and the tweeter under the dash, and "port" the sound from both through the air vents. Note that the air vents are to provide a "stealth" installation - there will not be any AC or heat in the vehicle.

I briefly considered horns as an option, but these seem to be very rare.

I'm in the "old-school" club and my last build was in the mid-90s, so I have been out of the scene for awhile. I appreciate any recommendations or feedback.
 

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I am not seeing any pictures and the link didn't work for me.

My first thought was horns mounted under dash, but I am also rather old school. With modern 3-D printing, I would think it would easier to design and print a horn with the proper throat and mount than it was back in the olden days. Maybe some sort of 4" firing down into a horn that flares forward flush with the dash? Maybe a horn with the flared opening to match the air vents with the speakers mounted deeper into the dash?

What sort of sound are you looking for? Are you looking for sound quality with a full range response or just looking for some music when you cruise?
 

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Foot room in a Deuce is tight (I know, I've got a '30 coupe) and depending on engine choice, firewall mods, and pedal set-up, something to consider is an era correct heater, like a Ha Dees.
Refurbish the outside and replace the guts with your audio.
It's a tight fit, but mids and tweets can be mounted facing the passengers, hidden behind the dampening doors, and midbass can be tucked up under the dash.
Open the doors when you want to listen, close them when you want to be stealth. Best of both worlds.
 

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Micro amps with built-in Bluetooth, have also really changed the game when it comes to shoe horning equipment into a small hotrod platform.
 

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80mph with the top down?

Hard to imagine that will be possible to create good sound there.

My CLK cabriolet quits making good sound at about 50mph with all the windows down. IF I put up all 4 windows I can have good sound up to about 80mph, especially with the wind blocker in.

Love the car you've chosen, and I hope that folks can help you find a good setup to put in there. Lots of amazingly small Class D amps to consider, especially with bluetooth as discussed.

I ended up leaving the audio stock in my 1969 T Bird for the 7 years I owned it.
 

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Honestly, with an open air car like that, I wouldn't try to get too extensive with it. I would probably do something like the new Arc PS8-50 powering some slim components in the kicks and a sub or sub(s) in the trunk. The PS8-50 is a full PS8-Pro DSP with a 65W x 8 @ 4 Ohms/100W x 8 @ 2 Ohms amplifier that can bridge channel pairs for 200W @ 4 Ohms. Pair that with a set of Morel Virtus Nano 602s (0.7" deep) and the subwoofer(s) of your choice that meet your space requirements in the trunk.
 

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I've got an all-original '32 B pickup that is still 6v, so I haven't done any audio in it....plus road & mechanical noise is fairly loud with the original wood floor-board, haha, so there's that. :p

Would a "temporary stealth" setup work?

What I'm thinking of is something like the Audiofrog GS42 4" Coaxial Speakers mounted in small custom ~1.5L sealed boxes (filled with polyfill or wool) that would hinge, pivot, or slide down on simple rails or a vertical rod from under each far left and right under-dash corner.

When parked, the small boxes could be pushed up under the dash and held in place by strong neodymium magnets. And the same type of magnets might hold them in their working position as well.

You can get period- or vintage-style grill cloth from vintage electric guitar amplifier restorers to make some nice protective speaker grills.

With fiberglass, you might even be able to mold a small 0.35cf-0.5cf sealed enclosure (again, filled with polyfill or wool) under the dash for a 6.5"-8" down-firing DVC subwoofer to cover the low end.

The small speaker boxes could be fabricated from wood, metal, or fiberglass. And either painted or covered in matching vinyl or leather, etc. The speakers could be aimed straight back towards you for the highest output and clarity. Subwoofer frequencies are omni-directional so the subwoofer could down-fire from under the dash. Or you could do a more traditional subwoofer setup with the box and the amplifier(s) in the trunk if you don't have the fuel tank and/or other gear there taking up space.

I think you'd be surprised at how good this setup can sound. ;) Just using the simple L/R "Balance" control will give you a decent center image if desired.

As mentioned, if you can't or don't want to install a traditional car stereo head unit, just use a decent Bluetooth Receiver with strong RCA preamp outputs on it and stream music to it using your Smartphone as the "Head Unit" using its built-in music player or streaming apps (Spotify, Pandora, Tidal, etc.).
JL Audio MBT-RX Bluetooth Receiver

The Bluetooth receiver's RCA outputs would feed a small 2-channel "micro amplifier" (or a 4-channel for speakers + a subwoofer). You would want an amplifier with High Pass and Low Pass Filters for the 4" coaxials & the subwoofer respectively, and one that you can bridge the rear channels to provide a higher-power mono channel for the subwoofer. The Rockford Fosgate Punch PBR400X4D might be a really good choice if it will fit.

I really like the power/size ratio & SQ of the Pioneer PRS-D800 amps, too, but they don't have built-in HPF or LPF. I personally don't think that you need to run a DSP for this set up, but it's always an advantage if you have the space and money.

Just some possibilities...
 

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Discussion Starter #13
Thanks for the creative ideas!

To add some context, I'm looking to enjoy music while cruising around town and on the highway. With the open environment, I'm just looking for "acceptable" sound quality and volume.

The quick and easy solution is to buy a portable bluetooth speaker ($200-300), with a mount under the dash (such as velcro or hooks). Then, the speaker can be in place for driving, and then removed for an event. But I'm betting we can do better than that.

The original heaters look cool, but it looks like it might fit only one midrange.

I really like the idea of having the speakers drop down from behind the dash, and fold up to be hidden. The tweeters could either be installed with them, or behind the air vents in the dash.

One question for you...What's about having coaxial speakers under the dash that faces the driver / passenger, fired through an inverted cone, and out a 2.75 inch air vent? The length of the cone would be short, but the opening for the sound would be much smaller than the midrange (2.75 inches vs. 5-6 inches). Since the cone would be inverted, this will change the sound of the midrange. But I'm not sure if the impact may be small, or if this is a terrible idea.

I am planning to use a bluetooth receive and there is room for any amps that may be needed.

Thanks again.
 

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Discussion Starter #15
This is an example of the air-vent.

There would be a gauge cluster in the center of the dash, likely with 5 gauges. Then, there could be a 2.75 inch air vent on the outside of the gauge cluster.
 

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