8" vs 10" truck Tuba

For livingroom sound better than in a theatre.
Message
Author
jimbo7
Posts: 849
Joined: Fri Dec 28, 2012 10:45 am
Location: St. Louis

Re: 8" vs 10" truck Tuba

#31 Post by jimbo7 »

Good job Seth :clap: If I built mine like that then I could still pile all my junk on it in the back of my suv
BFM builds:
XF212
T24 BP102 24"
2x SLA's 6-5" mids, 9- gt-302's
2x AT 14" MCM 55-2421
TrT 5" MCM 55-2421
AT 18" JBL GTO804
2x OT12 flat array
2x SLA Pro 2-Alpha 6's 2-Goldwoods
2x T39 24" 3012lf
Simplex 10 BP102

User avatar
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#32 Post by Seth »

jimbo7 wrote: Thu Apr 30, 2020 9:17 am Good job Seth :clap: If I built mine like that then I could still pile all my junk on it in the back of my suv
That's what had me choose the TruckTuba over the standard AutoTuba. An AutoTuba would fit, but I felt it would consume too much floor space in the hatch area, where the TruckTuba would essentially just raise the floor. We'll see, but this should work well for me.
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
AntonZ
Posts: 2664
Joined: Sun May 14, 2006 6:00 am
Location: NL

Re: 8" vs 10" truck Tuba

#33 Post by AntonZ »

Yeah it looks great indeed, but the million dollar question is: we wants to know what it sounds like in the vehicle. You hooked it up yet in the SethMobile?

User avatar
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#34 Post by Seth »

AntonZ wrote: Thu Apr 30, 2020 5:58 pm Yeah it looks great indeed, but the million dollar question is: we wants to know what it sounds like in the vehicle. You hooked it up yet in the SethMobile?
I don't have an amp in the car yet, but yes... I couldn't wait. I set the limiter for 25 volts (a little higher than rated) on the Ashly amp and put the cab in the car.
20200430_155940.jpg
.
Outside the vehicle it's not impressive at all. Which is just fine by me. Inside, it's pretty insane. Literally mind numbing. Flexing doors and hatches. It's very impressive. Plays sub 20Hz content like a boss. At 25v, it's waaaaaaay more than I'll need to augment the factory sound system.

I wired the drivers in parallel, which should be roughly a 4ohm load after adding the cabs impedance. I ran an impedance sweep to verify.
TruckTuba.jpg
.
I've had this old Alpine amp kicking around for a long time. I've never used it and don't even remember when, where, or why I acquired it. It's definitely been used by someone somewhere. It's rated 40wpc @ 4ohms or 120 watts bridged @ 4 ohm. I think it will be plenty, if not excessive for my current needs.

20200430_125227.jpg
So, I had the lumber, I had the drivers, I had the amp... this is like a free upgrade :cowboy:

After having used the Dayton DSP in one system, I now feel like I need it in any vehicle install. I can't think of another way to really pimp out the response curve. Even for just the sub, I'd be able to dial in the perfect curve. I'm wrestling with myself about that because it's a slippery slope. Next thing you know I could be eyeballs deep into upgrading the whole system. It doesn't sound bad as is and I'm really trying my best to resist that temptation.
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
Tom Smit
Posts: 7457
Joined: Sat Jan 05, 2008 1:24 pm
Location: Sarnia, Ont. Canada

Re: 8" vs 10" truck Tuba

#35 Post by Tom Smit »

Lookin' good Seth.
When I saw that you were using dual drivers, and in a Golf, I thought that 5v would likely be enough for regular listening(90dBA). Would you measure it to see how close I am?
TomS

Grant Bunter
Posts: 6915
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: 8" vs 10" truck Tuba

#36 Post by Grant Bunter »

Fit's nicely in that car Seth, great build.

Get it in there an running with that alpine amp for now.
Let it run for a few months. If, after that, you reckon you need to pimp it out with DSP, then you gave it a crack lol...
Built:
DR 250: x 2 melded array, 2x CD horn, March 2012 plans.
T39's: 4 x 20" KL3010LF , 2 x 28" 3012LF.
WH8: x 6 with melded array wired series/parallel.
Bunter's Audio and Lighting "like"s would be most appreciated...

User avatar
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#37 Post by Seth »

Tom Smit wrote: Thu Apr 30, 2020 10:36 pm Lookin' good Seth.
When I saw that you were using dual drivers, and in a Golf, I thought that 5v would likely be enough for regular listening(90dBA). Would you measure it to see how close I am?
I've got an inexpensive dB meter somewhere in my stuff. I've probably had it for at least 15 years. Scosche brand, I think. I'm also pretty sure it's dBc, so we'll just have to manually un-weight the reading and give it a +/- 3dB courtesy window for it's undoubtedly questionable accuracy. I'll look for it tomorrow.
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
AntonZ
Posts: 2664
Joined: Sun May 14, 2006 6:00 am
Location: NL

Re: 8" vs 10" truck Tuba

#38 Post by AntonZ »

SethRocksYou wrote: Thu Apr 30, 2020 7:12 pm
AntonZ wrote: Thu Apr 30, 2020 5:58 pm Yeah it looks great indeed, but the million dollar question is: we wants to know what it sounds like in the vehicle. You hooked it up yet in the SethMobile?
I don't have an amp in the car yet, but yes... I couldn't wait. I set the limiter for 25 volts (a little higher than rated) on the Ashly amp and put the cab in the car.

20200430_155940.jpg
.
Outside the vehicle it's not impressive at all. Which is just fine by me. Inside, it's pretty insane. Literally mind numbing. Flexing doors and hatches. It's very impressive. Plays sub 20Hz content like a boss. At 25v, it's waaaaaaay more than I'll need to augment the factory sound system.
"Like a boss" :cowboy: I love it. Knew you were gonna like it. Well done :clap:
Damn, next thing you know you make me dig up the ole AutoTuba and put it back in my current ride.

User avatar
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#39 Post by Seth »

AntonZ wrote: Fri May 01, 2020 2:29 pm "Like a boss" :cowboy: I love it. Knew you were gonna like it. Well done :clap:
Damn, next thing you know you make me dig up the ole AutoTuba and put it back in my current ride.
It's been a good handful of years since I had my dual loaded 20" TAT in a vehicle and this TruckTuba seems to be every bit as good at it's job. Granted, I'm basing (no pun intended) that off my memory of a visceral experience I haven't had in close to ten years. In any case, there is no let down or short coming within the design of the TruckTuba.

A little side note; have you ever put your ear up to a cloths dryer vent. There's a subtle sound of air rushing through the tubing and hose. I tried breaking in the drivers yesterday, while they were in the box. I set the voltage for 10 and swept up and down the frequency range looking for one that had the most cone movement and settled on 20Hz. Other than the low hum and rattle of pretty much everything in the place, I could hear subtle noise that sounded a little like static, or white/pink noise. Not sure how to spell how it sounded exactly. Kinda like a shshshshsh, but lower frequency. Sh, but using the back of the tongue instead of the tip to make the sound. Anyway... The subs are pumping away and I'm looking around for where the sound is coming from. I turned the subs off to help me locate it and the sound went away. Okay. Subs back on, now listening to the mouth of the TruckTuba and I can clearly hear rushing air. Turbulence, I suppose. I did rounded-over and sanded the tips of each protruding panel smooth. But, my guess is it's the last turn into the driver chamber. The dimensions are pretty tight to move that much air... and it is moving a lot of air, you can feel it moving at the mouth even. Wasn't even pulsing, just a constant sound of moving air, very similar to a dryer vent (without the tick tick tick of the random zipper clanking around). Fortunately, there's zero evidence of it in-car. Can't hear it one little bit.

:bash: put your AT back in the car :bash: put your AT back in the car :bash: put your AT back in the car :bash: put your AT back in the car :bash:

That's the best I could do to twist your arm over the internet :fruit:
Last edited by Seth on Fri May 01, 2020 7:00 pm, 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
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#40 Post by Seth »

My mind is currently churning on a way to refold the TruckTuba into the more typical long thin wedge shape cabinet that's typically needed in standard cab trucks. A buddy of mine gave me dimensions of 63" wide, 18" (might be 16", don't have it in front of me ATM) tall, 5" deep at the top, 9" deep at the bottom.
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

jimbo7
Posts: 849
Joined: Fri Dec 28, 2012 10:45 am
Location: St. Louis

Re: 8" vs 10" truck Tuba

#41 Post by jimbo7 »

Good luck with that project.

Is the noise you're hearing kinda like a leak when you put the tube up to your ear? Probably just the air moving like you said. I'm sure you're not gonna be playing a constant 20hz tone all the time :roll:
BFM builds:
XF212
T24 BP102 24"
2x SLA's 6-5" mids, 9- gt-302's
2x AT 14" MCM 55-2421
TrT 5" MCM 55-2421
AT 18" JBL GTO804
2x OT12 flat array
2x SLA Pro 2-Alpha 6's 2-Goldwoods
2x T39 24" 3012lf
Simplex 10 BP102

User avatar
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#42 Post by Seth »

jimbo7 wrote: Fri May 01, 2020 6:05 pm Good luck with that project.

Is the noise you're hearing kinda like a leak when you put the tube up to your ear? Probably just the air moving like you said. I'm sure you're not gonna be playing a constant 20hz tone all the time :roll:
Nothing like the leak I found around the perimeter of the driver in the T39. That was a pulsing tss tss tss that I could only hear with an implement (I used a McDonnalds straw. Was the best I had at the moment. Worked just fine.) This is the sound of much, much more air. It's almost like a snow storm sound effect in a low budget movie or cartoon. Fortunately, it's not something that can be heard in the car. And even in the garage, if I were playing actual music, I wouldn't hear it over the rest of the music. It's not too loud. But, obviously loud enough to notice on it's own. I'll see if the camera will record it with any intelligibility.
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
Site Admin
Posts: 28619
Joined: Tue May 02, 2006 5:59 pm

Re: 8" vs 10" truck Tuba

#43 Post by Bill Fitzmaurice »

To understand why you hear the air noise look at an equal loudness chart. The chuffing is probably in the 200-500Hz range.

User avatar
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#44 Post by Seth »

Bill Fitzmaurice wrote: Fri May 01, 2020 9:36 pm To understand why you hear the air noise look at an equal loudness chart. The chuffing is probably in the 200-500Hz range.
That's exactly what I thought of at the moment, equal loudness curves. Funny you bringing it up too.
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
Seth
Posts: 2731
Joined: Thu Sep 10, 2009 8:06 pm
Location: Sacramento, California, USA
Contact:

Re: 8" vs 10" truck Tuba

#45 Post by Seth »

Tom Smit wrote: Thu Apr 30, 2020 10:36 pm Lookin' good Seth.
...I thought that 5v would likely be enough for regular listening(90dBA). Would you measure it to see how close I am?
Alright Tom... So here's what I was able to collect. I really don't think the measurements are accurate though. Or maybe my conversion is off.

Here's what I did; I set the voltage first. Played a sine wave, recorded the actual voltage (it changed slightly with frequency), stood outside the car with the door open and moved the meter around the area where my head would be for about 10 seconds with the meter indicating the maximum, write down the figure, next frequency... wash, rinse, repeat for each of the 3 voltages, I tested at 1.4 volts, 5 volts, and 22-23 volts.

The only processing after the signal generator in the signal chain is a limiter that was not engaged. No EQ. Purely the response of the cabinet and vehicle.

Here's what I measured at 1.4 volts (variance 1.39-1.50 volts)
20Hz 107.9dBc
25Hz 105.3dBc
30Hz 102.4dBc
40Hz 102.4dBc
50Hz 102.8dBc
60Hz 102.2dBc
70Hz 104.6dBc
80Hz 100.1dBc
90Hz 91.1dBc
100Hz 89.7dBc

Here's what I measured at 5 volts (variance 4.61-5.03 volts)
20Hz 117.5dBc
25Hz 114.6dBc
30Hz 112.4dBc
40Hz 111.5dBc
50Hz 110.5dBc
60Hz 108.6dBc
70Hz 111.6dBc
80Hz 109.5dBc
90Hz 101.5dBc
100Hz 101.5dBc

Here's what I measured at 22 volts (variance 21.56-23 volts)
20Hz 123.3dBc
25Hz 123.4dBc
30Hz 122.2dBc
40Hz 123.4dBc
50Hz 123.4dBc
60Hz 120.2dBc
70Hz 122.5dBc
80Hz 120.3dBc
90Hz 112.0dBc
100Hz 109.5dBc

I used this chart to come up with the following dBc to dBa conversion figures.

Image

To me that looks like add x to the dBc reading to equal dBa
20Hz +44
25Hz +40
30Hz +37
40Hz +33
50Hz +28
60Hz +26
70Hz +24
80Hz +21
90Hz +20
100Hz +19


Here's why I think something's off. If I convert the 22 volt, 20Hz reading from dBc to dBa... yeah, it's pretty darn loud but I don't think it's 167.3dBa loud.

Cheap meter? Poor metering technique? Conversion all wrong? Dunno. But, let's blame the meter. :mrgreen:

Anyway... There ya go :thumbsup:
Last edited by Seth on Sun May 03, 2020 9:10 pm, 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

Post Reply