8" vs 10" truck Tuba

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Bill Fitzmaurice
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Re: 8" vs 10" truck Tuba

#16 Post by Bill Fitzmaurice »

I wouldn't use coaxes. They put the tweeters too low. They need to be as high as possible, with swivel mounts to aim them at the listeners.

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Seth
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Re: 8" vs 10" truck Tuba

#17 Post by Seth »

For many reasons, I agree with you Bill. However, I've done both ways and sometimes I'm okay with the results of a coaxial in a door or kick panel. Not every time, just sometimes... sometimes it's good enough for the girls I hang out with. It's easy enough to add a tweeter in a more appropriate location after the fact and just eliminate the tweeter on the coaxial by either clipping the leads to the tweeter, cut the frequencies out with a low pass, or both.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Tom Smit
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Re: 8" vs 10" truck Tuba

#18 Post by Tom Smit »

I have read good results on Silverflute woofers on DIY audio. My son has a pair and really likes them. Here is a link to a 6.5" https://www.madisoundspeakerstore.com/s ... wool-cone/
TomS

iSurfSouthChinaSea
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Location: Saint Petersburg, Florida

Re: 8" vs 10" truck Tuba

#19 Post by iSurfSouthChinaSea »

That 9conductor wire seems like a swell deal. I see that PE has a buyout of a 4"x6" that they are calling a "subwoofer."
I will upload a photo soon. It's a very challenging vehicle to get decent soundstage. If the truck tuba sub has decent output, I am going to need decent mid bass do give it musicality. So I can't get too Joe Dirté on this. I was thinking the HLCDs under dash might be worth it. Again, this is not a daily driver. My old WRX is my normal weekend beach car and half the time I am listening to NPR. But its the other half I am worried about. Good sound in the automotive environment is therapy for me. And it's time to sell the WRX hence the new vehicle and new audio.

Those Silver Flute drivers looks decent and not expensive compared to the Scanspeak stuff. I think that Fatai 4" would be cool but not running free-air. The 6.5" Eminence seems to have the best specs. But what kind of baffle or enclosure?

What is the useful upper limit of the auto tuba for purposes of crossing over? I am willing to take a hit on the sub becoming directional but ideally I would be crossing over at 90hz. If I could run it higher than the mid bass up front becomes much easier.

Any who, I appreciate the help and feel more comfortable here than the car audio forum scene, even if I have yet to ask an intelligent question.

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Bill Fitzmaurice
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Re: 8" vs 10" truck Tuba

#20 Post by Bill Fitzmaurice »

iSurfSouthChinaSea wrote: Wed Apr 22, 2020 12:13 am Those Silver Flute drivers looks decent and not expensive compared to the Scanspeak stuff. I think that Fatai 4" would be cool but not running free-air. The 6.5" Eminence seems to have the best specs. But what kind of baffle or enclosure?
Stick them in the doors. Doors work like lossy sealed boxes, so low Q drivers don't work as well as higher Q drivers. Q between 0.5 and 1.0 will give the best results. Low Fs comes at the cost of sensitivity, so there 60-120Hz is best.

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Re: 8" vs 10" truck Tuba

#21 Post by iSurfSouthChinaSea »

Here is what I will be dealing with. This car needs a serious detail. So between that and the overkill car audio project that should keep me busy for the covid-19 doldrums. I'll just leave the factory 4x6s alone.

I al looking at the lower door area, which concave into a triangular shape. It's bare sheet metal. Haven't taken off door panels to see what's going on but the doors seem reasonably solid. With the WRX, taming the plastic throughout the car was the biggest challenge. I am thinking a plywood baffle and a hole, unless I can find a pod or something that fits.

Has anyone heard of PRV? These seem to have decent enough specs, mounting depth and seem reasonably priced per pair.
https://www.parts-express.com/prv-audio ... --294-2839

On the pricey end, Morel has these dome mid bass drivers. Interesting design but a little too exotic I guess. https://www.parts-express.com/morel-pow ... m--287-040

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Bill Fitzmaurice
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Re: 8" vs 10" truck Tuba

#22 Post by Bill Fitzmaurice »

PRV is Brazilian, pretty good stuff. Those midbasses look good, but I wouldn't take them higher than 3.5kHz, above that dispersion would be too narrow. High priced drivers make no sense. You're in a car, not Carnegie Hall.

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Re: 8" vs 10" truck Tuba

#23 Post by iSurfSouthChinaSea »

o.k. The UM8 is ordered. I found some 6.5" that have been sitting on shelf for at least 10 years.
Anyone remember a/d/s? I'll try these first since they are there.
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Tom Smit
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Re: 8" vs 10" truck Tuba

#24 Post by Tom Smit »

You can fab up some tweeter pods on the A pillars using an old t-shirt, resin, and then fibre glass, if you like. It puts the highs up where you can hear them.
TomS

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Seth
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Re: 8" vs 10" truck Tuba

#25 Post by Seth »

Bill, what would the minimum width need to be to load a TruckTuba with 2 MCM 8's? I'm building mine 8.5" wide, 7.5" panels. It looks like I can easily fit 2, side-by-side, surface mounted in panel 1. I've been sitting on 4 spare drivers since 2009 and It'd be great to put them to use instead of collecting (more) dust.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Seth
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Re: 8" vs 10" truck Tuba

#26 Post by Seth »

20200427_161840.jpg
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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Bill Fitzmaurice
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Posts: 28620
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Re: 8" vs 10" truck Tuba

#27 Post by Bill Fitzmaurice »

That width will work.

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Seth
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Re: 8" vs 10" truck Tuba

#28 Post by Seth »

Bill Fitzmaurice wrote: Mon Apr 27, 2020 9:11 pm That width will work.
Hot diggity! :hyper:

Thank you Bill :thumbsup:
Last edited by Seth on Tue Apr 28, 2020 11:11 am, edited 1 time in total.
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

User avatar
Bill Fitzmaurice
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Posts: 28620
Joined: Tue May 02, 2006 5:59 pm

Re: 8" vs 10" truck Tuba

#29 Post by Bill Fitzmaurice »

Make sure there's enough bracing in the driver compartment to handle the pressure from two drivers.

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Seth
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Re: 8" vs 10" truck Tuba

#30 Post by Seth »

Figured I'd add to this thread too. I did add extra bracing per Bills instruction... I added a 6/9 brace, 7/9 brace, cross mouth brace, and gusseted between the drivers with a strip of ply about 3" wide, anchoring the middle of panel 1 into the sides.

Here it is completed.

Image
Build in process - 2 WH6, one Alpha 6a loaded, one PRV Audio 6MB250-NDY loaded

Two 2x6 shorty SLA Pro's
One T39, 16", 3012LF loaded
Tall AutoTuba, 20" wide, 2x 8" MCM 55-2421
TruckTuba, 8½" wide, 2x 8" MCM 55-2421

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