Truck Tuba needed power? What is the minimum

[mpm17]

I have started building a truck tuba using one of the recommended Dayton Audio LS10-44. The truck tuba will be seven(7) total inched thick. This will go in my Jeep Liberty lying flat in the hatch area strapped down for safety. My front stage amplifier is the JBL DSP4086 using six of the eight channels. It's full DSP 8 channel amp at 40 watts per channel in a 4ohm load. A subwoofer in this system would usually have its own amplifier that would get its low level signal from the 7th and 8th channel on the JBL amplifier. It designed that way specifically so you can use it at 40 watts/channel or low level signal. My thoughts are since tuba subs are so efficient would the 7th and 8th channel at 40 watts each drive the dual voice coil speaker enough to skip the second amplifier? If my math is correct that would be 80 watts total . Both channels can be driven exactly the same so no concerns with a left and right signal. Its still a mono signal. You cannot bridge the channels so driving each voice coil at 4 ohms is the most you can get out of the amplifier in this case.

I do not usually listen at loud levels. Just occasionally cranking it with Rush. I'm not concerned with ultra low frequency reproduction so normally nothing below 40Hz. Crossover to the front stage will be in the 60 to 70Hz range. Crossover slope can be whatever it needs to be thanks to the DSP abilities.

[Seth]

...using one of the recommended Dayton Audio L10-44...

Interesting. My copy of the plans does not list the L10-44 as a recommended driver. Is it listed in your copy of the plans as a recommended driver or was the L10-44 "recommended" by a source outside the plans?

...would the 7th and 8th channel at 40 watts each drive the dual voice coil speaker enough to skip the second amplifier?... ...I do not usually listen at loud levels...

Give it a shot. Peak potential volume would only be down 3-4dB compared to running it with a 150-200 watt amplifier. 3-4dB is a noticeable difference. But, just barely noticeable.

[Bill Fitzmaurice]

Crossover to the front stage will be in the 60 to 70Hz range.

That's probably too low. Car door speakers are seldom able to do much below 100Hz,

[mpm17]

...using one of the recommended Dayton Audio L10-44...

Interesting. My copy of the plans does not list the L10-44 as a recommended driver. Is it listed in your copy of the plans as a recommended driver or was the L10-44 "recommended" by a source outside the plans?

...would the 7th and 8th channel at 40 watts each drive the dual voice coil speaker enough to skip the second amplifier?... ...I do not usually listen at loud levels...

Give it a shot. Peak potential volume would only be down 3-4dB compared to running it with a 150-200 watt amplifier. 3-4dB is a noticeable difference. But, just barely noticeable.

My apologies. Its the Dayton Audio LS10-44. Last sentence in the third paragraph. I bought my plans earlier last year so they may have included an update.

I don't mind being down a little bit. I was just concerned it would be a futile attempt. Thanks.

[mpm17]

Crossover to the front stage will be in the 60 to 70Hz range.

That's probably too low. Car door speakers are seldom able to do much below 100Hz,

Thanks for the input Bill. The doors are heavily treated so hopefully they will do better than normal. I am currently running some Silver Flute 6.5". Awesome for the price but limited on lower extension. I'll adjust as good as possible when tuning. The DSP makes it easy.

[Bill Fitzmaurice]

If that's the W17RC38-04 they'd be very limited in low end, as their low Q isn't suited for car doors. F3 is probably around 130Hz, SPL at 70Hz perhaps 80dB.

[mpm17]

If that's the W17RC38-04 they'd be very limited in low end, as their low Q isn't suited for car doors. F3 is probably around 130Hz, SPL at 70Hz perhaps 80dB.

It is those. I have others to pick from. Higher Q is desirable? How about the CDT Audio listed below.

https://www.cdtaudio.com/cdtnew22/produ ... 6imkhr.php

[Seth]

My apologies. Its the Dayton Audio LS10-44. Last sentence in the third paragraph. I bought my plans earlier last year so they may have included an update.

I'll make a note of that. Thanks for letting me know

I don't mind being down a little bit. I was just concerned it would be a futile attempt. Thanks.

Oh yeah, you'll have plenty then. Please keep us posted on your progress and impressions once it's completed and installed.

And please feel free to ask any questions that arise along the way.

FWIW, I agree with Bill. Not so much from a capability standpoint, but frequencies below about 120ish Hz are not really locatable as to whether the sound came from the doors or whether the sound came from the trunk/cargo area. And since those frequencies are also the frequencies that demand more and more output as the frequency goes lower and lower to sound good, it only makes sense to have those frequencies handled by the Truck Tuba, since it's designed specifically to make those frequencies AND it has much higher sensitivity than the doors will have in the sub 125ish Hz frequency range. It could potentially eat up all the available voltage gain the amp has to offer to create a frequency in the doors that would only require a small amount of voltage gain for the Truck Tuba to create the same frequency at the same volume.

Ultimately, I know we all have a plan in our heads of how it's all going to go. It sounds like you may have your mind set on doing it a certain way and there's nothing patently wrong with that. I think we all do it. I would, however, like to urge you to try it a bunch of different ways and stick with whatever sounds better to you. One of the beauties of DSP... as long as there's a "save settings as a preset" option, it's super easy to make A/B comparisons of different tuning strategies.

[mpm17]

And please feel free to ask any questions that arise along the way.

Ultimately, I know we all have a plan in our heads of how it's all going to go. It sounds like you may have your mind set on doing it a certain way and there's nothing patently wrong with that. I think we all do it. I would, however, like to urge you to try it a bunch of different ways and stick with whatever sounds better to you. One of the beauties of DSP... as long as there's a "save settings as a preset" option, it's super easy to make A/B comparisons of different tuning strategies.

I do have a plan. Actually many different configurations that revolve around the 8 channel amplifier. I just had the idea of a tuba sub this weekend. No additional power wires for an additional amplifier would be nice. I like simple as long as it does not compromise excessively. I am going to try it with the higher crossover points and the 8 channel. If no bueno then I have an amplifier on stand by.

I am going to do a build thread with my results and what it took to get there. Thanks for your input and insight.

[Bill Fitzmaurice]

How about the CDT Audio listed below.
https://www.cdtaudio.com/cdtnew22/produ ... 6imkhr.php

Silly expensive, and the Q is still too low. It should be above 0.5, preferably around 0.7, with Fs 80-90Hz. You don't need to spend more than $60.

[mpm17]

How about the CDT Audio listed below.
https://www.cdtaudio.com/cdtnew22/produ ... 6imkhr.php

Silly expensive, and the Q is still too low. It should be above 0.5, preferably around 0.7, with Fs 80-90Hz. You don't need to spend more than $60.

These are silly cheap. Q is 0.95 Fs of 52Hz F3 61.4Hz. And I have two sets sitting on the bench. Can Q be to high? These don't have to play any higher than 700 to 800Hz if that matters.

https://www.parts-express.com/6-1-2-Pol ... quantity=1

[Bill Fitzmaurice]

Qes is a bit high. F3 is a respectable 85Hz, there's a midbass hump at 120Hz, but overall sensitivity is only 85dB. I'd still toss one in to see, since you have it on hand. With DSP correction it could be pretty good. You can't beat the price. What you're mainly paying for with higher priced drivers is lower Q, which gives better sensitivity but they don't work well in sealed enclosures.