Tuba HT as sound reinforcement

For livingroom sound better than in a theatre.
Message
Author
Robin Dobbie
Posts: 15
Joined: Tue Mar 19, 2019 8:28 am
Location: Dallas Ft. Worth Area

Tuba HT as sound reinforcement

#1 Post by Robin Dobbie » Sun May 12, 2019 12:38 am

Someone posted a question a while back about comparing the Tuba 60 and HT sensitivity. They got a non-answer response saying "never use the Tuba HT for DJing because you'll blow the drivers" yadda yadda.

I read that 35v is what the Tuba HT with a single Dayton 15 should be limited to. Should that be lower if used close to maximum performance?

Also, what is the 1w/1m sensitivity at 25hz of the 24" wide Tuba HT with the Dayton?

Image

I overlaid two graphs, but since I assume they're useless USELESS 2.83V I can't possibly compare them.

Grant Bunter
Posts: 6096
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Tuba HT as sound reinforcement

#2 Post by Grant Bunter » Sun May 12, 2019 1:58 am

Robin Dobbie wrote:
Sun May 12, 2019 12:38 am
Someone posted a question a while back about comparing the Tuba 60 and HT sensitivity. They got a non-answer response saying "never use the Tuba HT for DJing because you'll blow the drivers" yadda yadda.

I read that 35v is what the Tuba HT with a single Dayton 15 should be limited to. Should that be lower if used close to maximum performance?

Also, what is the 1w/1m sensitivity at 25hz of the 24" wide Tuba HT with the Dayton?

Image

I overlaid two graphs, but since I assume they're useless USELESS 2.83V I can't possibly compare them.
There's at least 1 reason it is said not use HT designs of Bill's for any other purpose.
That's because it's been tried and failed.

The issue (perhaps) is not understanding that the SPL chart at the top of the Tuba HT sales page is that it also includes corner loading, which = +12dB.
You will often not be able to have corner loading in a venue, and certainly not even get wall loading outdoors.
So, if you want to do a apples to apples comparison, take 12dB of the Tuba HT chart and overlay that.

The Tuba HT also benefits from cabin gain, the T60 doesn't, unless you use it as a HT sub.

Sensitivity with the Dayton will be the same as with the Tempest, it's the cab that dictates response, not the driver.

You may well have read about a 35V limit, but any limit needs to come from Bill.
It's not usual for most HT owners to be able to brick wall limit.

Why is a 2.83V chart useless?
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

Robin Dobbie
Posts: 15
Joined: Tue Mar 19, 2019 8:28 am
Location: Dallas Ft. Worth Area

Re: Tuba HT as sound reinforcement

#3 Post by Robin Dobbie » Sun May 12, 2019 3:52 am

There's at least 1 reason it is said not use HT designs of Bill's for any other purpose.
That's because it's been tried and failed.
Failure could be any number of things, including insufficient limiting or insufficient knowledge of how much to limit them.
The issue (perhaps) is not understanding that the SPL chart at the top of the Tuba HT sales page is that it also includes corner loading
The tuba line in the graph I linked to was the freestanding "measurement" from the SPL chart page. I erased the corner-loading and whatever the other one was. Should be freestanding HT vs freestanding 60.

If everything was also measured at 1w/1m and I knew what the maximum, all-day-long, freestanding SPL at one frequency was, then that would answer so many questions. If I knew, oh ok, the T60 can do 94.7dB at 1w/1m at 25hz with a maximum of 120db with safe limiting, then I wouldn't have to ask as many stupid questions.
You may well have read about a 35V limit, but any limit needs to come from Bill.
It did, but I want to know if that's still the safe limit for DJing, not just watching movies or whatever.

Grant Bunter
Posts: 6096
Joined: Mon Nov 28, 2011 11:12 am
Location: Ilfracombe Queensland Australia
Contact:

Re: Tuba HT as sound reinforcement

#4 Post by Grant Bunter » Sun May 12, 2019 4:49 am

Robin Dobbie wrote:
Sun May 12, 2019 3:52 am
There's at least 1 reason it is said not use HT designs of Bill's for any other purpose.
That's because it's been tried and failed.
Failure could be any number of things, including insufficient limiting or insufficient knowledge of how much to limit them.

True. It could also be that the HT drivers used just aren't up to the task of doing a pro sound event, or a number of them.
The issue (perhaps) is not understanding that the SPL chart at the top of the Tuba HT sales page is that it also includes corner loading
The tuba line in the graph I linked to was the freestanding "measurement" from the SPL chart page. I erased the corner-loading and whatever the other one was. Should be freestanding HT vs freestanding 60.

Right. And the T60 is winning in every aspect right across the chart above 25Hz.
That makes it the cab to choose for that application.


If everything was also measured at 1w/1m and I knew what the maximum, all-day-long, freestanding SPL at one frequency was, then that would answer so many questions. If I knew, oh ok, the T60 can do 94.7dB at 1w/1m at 25hz with a maximum of 120db with safe limiting, then I wouldn't have to ask as many stupid questions.

On the Tuba HT page it says you can "take it to +126dB levels" in the home. Obviously that's not frequency specific, but neither is impedance (which varies with frequency), a critical element in determining voltage displacement limits.
You may well have read about a 35V limit, but any limit needs to come from Bill.
It did, but I want to know if that's still the safe limit for DJing, not just watching movies or whatever.

Easy. If a limit is given, it's given for those that have the ability to do so, in the environment for which the design is intended.
So, it's for music or movies at home, but not DJing at venues.
No, that doesn't make it ok to use at home parties at war volume all night.

I'm positive Bill would say the same, but use the right cab, not the wrong cab, for the job.
Built:
DR 250: x 2 (melded array) with March 2012 plans. 2 more under way with CD horn
T39's: 4 x 20" BP102 , 2 x 28" 3012lf.
WH8: x 3 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...

Robin Dobbie
Posts: 15
Joined: Tue Mar 19, 2019 8:28 am
Location: Dallas Ft. Worth Area

Re: Tuba HT as sound reinforcement

#5 Post by Robin Dobbie » Sun May 12, 2019 6:05 am

True. It could also be that the HT drivers used just aren't up to the task of doing a pro sound event, or a number of them.
Obviously there's a level at which the suggested driver could last indefinitely. I don't think it's too much to ask to get an answer from Bill on what that level is.
the T60 is winning in every aspect right across the chart above 25Hz
Do we know that? Are they wattage matched? The 60 in the chart was more than 50% larger. Seems like more than once I've read, in this forum even, it's better to have more smaller subs than just one or two larger ones.
use the right cab, not the wrong cab, for the job.
I'm not asking you to choose for me, I'm asking for the information to make an informed decision, myself.

I have a Tuba HT and I've already agreed to let someone borrow it for PA purposes. They have a limiter, I need to know what to tell them to limit it to.

User avatar
Bill Fitzmaurice
Site Admin
Posts: 26804
Joined: Tue May 02, 2006 5:59 pm

Re: Tuba HT as sound reinforcement

#6 Post by Bill Fitzmaurice » Sun May 12, 2019 8:14 am

Get it back from them. The THT is designed for home theater. Nothing about it is suitable for PA. As already noted we had one 'stable genius' who was absolutely sure that he knew more about our designs and how to employ them than anyone here, myself included, and built a herd of THT for PA against our advice. It did not end well. Besides, we have a mantra about lending out gear: Never lend anything that you won't mind getting back broken.

Robin Dobbie
Posts: 15
Joined: Tue Mar 19, 2019 8:28 am
Location: Dallas Ft. Worth Area

Re: Tuba HT as sound reinforcement

#7 Post by Robin Dobbie » Sun May 12, 2019 8:51 am

I'm the furthest thing from any kind of genius, but literally NOTHING about the THT is suitable for PA? I mean, we live in a world where most PA equipment sold isn't suitable for PA.

I suppose I would rather it be blown than go back on agreement, knowing the person is the kind of person who would take care of any damage.

My other option is to lend them my Cerwin Vega L-36's loaded with 18s, your favorite. But those are too big and heavy, and I suspect not even as loud, even with a pair. But I don't really know.

Since I have gotten no answers I suppose we'll limit the THT to say 20v. ¯\_(ツ)_/¯

Bruce Weldy
Posts: 6709
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Tuba HT as sound reinforcement

#8 Post by Bruce Weldy » Sun May 12, 2019 10:31 am

Robin Dobbie wrote:
Sun May 12, 2019 8:51 am
I'm the furthest thing from any kind of genius, but literally NOTHING about the THT is suitable for PA? I mean, we live in a world where most PA equipment sold isn't suitable for PA.

I suppose I would rather it be blown than go back on agreement, knowing the person is the kind of person who would take care of any damage.

My other option is to lend them my Cerwin Vega L-36's loaded with 18s, your favorite. But those are too big and heavy, and I suspect not even as loud, even with a pair. But I don't really know.

Since I have gotten no answers I suppose we'll limit the THT to say 20v. ¯\_(ツ)_/¯
Well, everyone is trying to get you to not do what you are doing. However, if you are going to do it, then just setting the limit correctly is only part of the solution. First of all, does your friend know how to set the voltage limit correctly? Is there a driverack or some other brick wall limiter involved? Do you have a voltmeter? That's a must or you can kiss the driver goodbye.

The other issue is high pass setting. I don't recall if you are going to use this for live sound or DJ work. If for live sound, then raise the high pass to 45-50hz. That's plenty of low end for a band and keeps the mud out. In fact, I'd keep it there for DJ, too. Since over-excursion is the killer here, raising the high pass will allow for more power without driver damage.

I can't tell you exactly how much you can put to that driver as it's not a pro sound driver. But raising the high pass should let you give it 30 volts if it is the Dayton RSS390 HF-4.

I understand wanting to honor your commitment, but I'd go with the CV subs to be safe.

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

ACUA
Posts: 347
Joined: Sun Sep 25, 2016 6:21 pm

Re: Tuba HT as sound reinforcement

#9 Post by ACUA » Sun May 12, 2019 12:54 pm

This is not the first time, but the first in a long time in which I find the content polarizing. The tools prescribed here are not user friendly and it seems to me that this forum is somewhat of a necessity for success. Whoever, we are still not given all the information and even if we were many of us would not grasp it. That said, I sort of side with the lend them out it’s your business not any of ours. Those who advise against it should be less vicious about how they don’t recommend doing it. The logical thing suggests there is a bad history and a lot of headaches from this topic. Perhaps I should reframe!!!

Against the popular opinion I have high interest in creating a way to measure driver excursion real time in the cabinets as well as set up temp sensors to monitor the drivers. This would allow me to push to the limits and be able to see exactly what is going on. I have ideas for the driver excursion limits but that’s not that easy for me. I work with excelerometers at work and may be able to attach a small one to a driver. I have some ideas about a switch mechanism but it’s clearly only partially baked.

Anyways I have seen autotubas places out doors with no loading and they worked just fine although they were intentionally not pushed hard I just can’t imagine not being able to get a THT to work well to a certain point.

I find this topic interesting as to why so much aggression. If this forum is designed to educate us lesser beings, is not this topic deserving of some proper elaboration.
Advanced concepts underground audio

Robin Dobbie
Posts: 15
Joined: Tue Mar 19, 2019 8:28 am
Location: Dallas Ft. Worth Area

Re: Tuba HT as sound reinforcement

#10 Post by Robin Dobbie » Sun May 12, 2019 1:43 pm

First of all, does your friend know how to set the voltage limit correctly? Is there a driverack or some other brick wall limiter involved? Do you have a voltmeter?
Yes to all. There's a DCX2496 involved. But I figure with that much high-pass filtering there's no point in hauling the huge tuba.

The CVs are a really no-go due to size and weight. They're the same size, but almost double the weight each, probably.

Thanks for at least throwing some suggestions out there instead of just saying "don't do it."
I just can’t imagine not being able to get a THT to work well to a certain point.
Exactly.

User avatar
BrentEvans
Posts: 3030
Joined: Thu Oct 09, 2008 10:38 am
Location: Salisbury, NC

Re: Tuba HT as sound reinforcement

#11 Post by BrentEvans » Sun May 12, 2019 5:52 pm

Robin,

You have made several comments referencing voltage and wattage in a way that would lead one to believe you may not completely understand how they matter as far as speakers are concerned.

Simply put, driver excursion is driven by voltage, and watts are consumed in the process depending on the impedance of the cabinet and can be calculated using Ohm's law. Accordingly amps generate voltage and supply watts. The amount of voltage an amp can generate may or may not be limited by its power supply, depending upon the amp, but when comparing one speaker to another, the ONLY way to determine which one is louder at a given level is to measure that based on voltage input, not watts consumed. The only reason watts are used as a measurement in commercial applications is that the numbers are bigger.

The only time using current (expressed in amps) or power (expressed in watts) as a comparison is when voltage is not a variable, such as in a light bulbs or space heaters.
99% of the time, things that aren't already being done aren't being done because they don't work. The other 1% is split evenly between fools and geniuses.

Bruce Weldy
Posts: 6709
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Tuba HT as sound reinforcement

#12 Post by Bruce Weldy » Sun May 12, 2019 6:04 pm

Robin Dobbie wrote:
Sun May 12, 2019 1:43 pm
But I figure with that much high-pass filtering there's no point in hauling the huge tuba.
Not really. I doubt the tops can handle anything down to 50hz with any volume....if they can, then a single Tuba wouldn't be able to keep up regardless, because that would mean they are some very high-end speakers. Cross around 100hz and the sub can handle the rest. I've high passed my subs at 47-50 hz for years and people are always blown away at the bottom end for live bands. Anything below that, especially inside, just adds a lot of mud in the mix.

If it's a DJ situation and you aren't trying to make people dirty their drawers, then 45-50hz is adequate for a one-off gig using a Home Theater sub. And high passing there just might get that driver through the night.

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Bruce Weldy
Posts: 6709
Joined: Fri Nov 27, 2009 11:37 am
Location: New Braunfels, TX

Re: Tuba HT as sound reinforcement

#13 Post by Bruce Weldy » Sun May 12, 2019 6:16 pm

ACUA wrote:
Sun May 12, 2019 12:54 pm
Those who advise against it should be less vicious about how they don’t recommend doing it. The logical thing suggests there is a bad history and a lot of headaches from this topic.
Having read this thread, I don't think anyone has been vicious at all, just laying out the facts that it's been tried and it's the wrong tool for the job.

And yes, it's easy to be a little short or curt with answers when someone is taking the wrong path, yet still pushes back. We could probably spend more time explaining the "whys" of our conclusions, but the folks that post regularly on this forum truly spend a lot of time here trying to help others. And sometimes its just easier to say "don't do it" rather than spend more time and effort trying to convince someone of why they shouldn't do it.

But hey, it's DIY - so give it a shot. We all learn more from our failures than our successes.......

6 - T39 4-25" 2-22" 3012LF
4 - OT12 2512 Melded/NSD2005
1 - T24
2 - XF210


"A system with a few knobs set up by someone who knows what they are doing is always better than one with a lot of knobs set up by someone who doesn't."

Robin Dobbie
Posts: 15
Joined: Tue Mar 19, 2019 8:28 am
Location: Dallas Ft. Worth Area

Re: Tuba HT as sound reinforcement

#14 Post by Robin Dobbie » Sun May 12, 2019 9:24 pm

Robin,

You have made several comments referencing voltage and wattage in a way that would lead one to believe you may not completely understand how they matter as far as speakers are concerned.
You are very astute and tactful, too. You're right. Guilty as charged. But if I look at say, Danley subs, there is enough information on their spec pages even for someone who's not an electrical engineer to get an idea how to compare any of their speakers. The only problem is how to come up with thousands and thousands of dollars to buy and haul around those chonkers! :lol: But when they list a continuous dB rating, or continuous power handling, I suspect it can be taken as gospel? Assuming whatever limiting and filter guidelines they may provide are followed. They have a sensitivity rating(it's OMG VOLTS again) but there is a rated impedance, so I can do something with that. I feel like with the Danley subs I can calculate to within a dB of what they can do with the sensitivity and continuous power handling they provide. Continuously. I assume their DTS10 is rated for whatever one might want to do with it, not just watching Titanic?

The problem is there is no continuous rating on the THT ...or many of the pro subs listed here. No rated impedance, either. As you said, the cabinet can affect that. So even though I have the driver's Re, I don't know anything useful. Apparently only Bill could offer technical guidance on some of these things, if he knows them he's not talking.

I assume before the stable genius tried the HTs as DJ subs there was no "it's been tried and failed" response? Because without that, and in the absence of comparable continuous dB ratings, the HT doesn't look too bad compared to the 60, especially when cabinet size is considered. Unless those two lines in the chart I posted in the first post have no business that close to each other?

One thing I did notice on the spl chart page for the tubas is that some of the table tuba charts have different language describing the measurements than some of the THT charts. We have "outdoorsgroundplane" and "freestanding." Are these identical? Or is freestanding indoors and somehow adding cabin gain?

ACUA
Posts: 347
Joined: Sun Sep 25, 2016 6:21 pm

Re: Tuba HT as sound reinforcement

#15 Post by ACUA » Sun May 12, 2019 10:29 pm

Bruce Weldy wrote:
Sun May 12, 2019 6:16 pm
ACUA wrote:
Sun May 12, 2019 12:54 pm
Those who advise against it should be less vicious about how they don’t recommend doing it. The logical thing suggests there is a bad history and a lot of headaches from this topic.
Having read this thread, I don't think anyone has been vicious at all, just laying out the facts that it's been tried and it's the wrong tool for the job.


And yes, it's easy to be a little short or curt with answers when someone is taking the wrong path, yet still pushes back. We could probably spend more time explaining the "whys" of our conclusions, but the folks that post regularly on this forum truly spend a lot of time here trying to help others. And sometimes its just easier to say "don't do it" rather than spend more time and effort trying to convince someone of why they shouldn't do it.

But hey, it's DIY - so give it a shot. We all learn more from our failures than our successes.......
He simply stated that it’s his best option and he is going to do it. Why can’t you simply provide best advice given the situation and actually be supportive. Instead of the, your way or the highway bit. If it’s so bad just give a little blurb telling why! it will be easy to heed the warning then. but to simply say don’t do something does not really help. It’s Bill’s world and your right to post your stance and opinion, I get it. I’m just saying there is a polarizing vibe spilling out of this thread.

I dare say that there is some grey area between giving a helping hand and feeding an ego when posting on this forum. To simply say don’t to something suggesting you know best and we should just follow leans on the ego end of the spectrum for me. Your helping sure but not very much.
Advanced concepts underground audio

Post Reply