What's to chat about?

[Seth]

Hmmm.

Again, you're asking the same questions I asked myself a couple weeks back, so I've got a bit of a head start in sifting through the logic

The purpose of building T48's is to have a HP of 35Hz with 4 or more cabs?

Or 40hz with less than 4 cabs, where the T39 has a recommended 45Hz High Pass with less than 4 cabs

So why would you want to cruel response below 40Hz by decreasing sensitivity in that region?

To my mind, a slight reduction in sensitivity from 35-40Hz is worth the trade off of gaining slightly from 40-125Hz where much more content will be played, yet still have the capability to impactfully represent the high 30Hz region and audibly play down in the low 30Hz region.

You may as well just build T39's. You'd save in ply and pack space.

Meh... doesn't excite me the same way. And as far as pack space, their footprint area when upright is essentially the same at 4 ft². I personally think the 24x24 footprint will pack and stack easier.

[Bruce Weldy]

Meh... doesn't excite me the same way. And as far as pack space, their footprint area when upright is essentially the same at 4 ft². I personally think the 24x24 footprint will pack and stack easier.

Nope.....the T39 is only 19-20 inches deep....and way easier to move around. I struggled between witch to build 10 years ago. Really glad I went with the T39. I have no need for the extra extension (most people don't, they just think they do). In fact, I typically high pass my 6 boxes at 47hz. I have plenty of low end for live music and recorded.....at least the stuff that I play.

[Seth]

Meh... doesn't excite me the same way. And as far as pack space, their footprint area when upright is essentially the same at 4 ft². I personally think the 24x24 footprint will pack and stack easier.

Nope.....the T39 is only 19-20 inches deep....and way easier to move around. I struggled between witch to build 10 years ago. Really glad I went with the T39. I have no need for the extra extension (most people don't, they just think they do). In fact, I typically high pass my 6 boxes at 47hz. I have plenty of low end for live music and recorded.....at least the stuff that I play.

If I went the T39 route, I'd build them 30" wide. 30 wide x 19.5 depth = 585 in² or 4.0625 ft² vs. 576 in²/4.00 ft² for the T48. The 39 has the larger foot print by 11 in².

I know for a fact that I wont "NEED" extension below 40 for the live stuff I do. However, I do know I'll wish I had it anyway. I high pass the subs I currently use at 40Hz. It's plenty for live, but tons missing from recorded music I like to listen to. If I went the T39 route, I know that I'd wish I would have gone with 48's. I'd much rather go bigger and wish I hadn't.

For me, it's such a close call between the two. As you guys are bringing up, it's not a super clean and clear decision. It's taken number crunching and soul searching to finally make a choice. In no way am I saying this choice is superior to the choice you guys made. It's just a different choice.

[Seth]

...So why would you want to cruel response below 40Hz by decreasing sensitivity in that region?...

To be honest, that was my initial thought too. This helped.

Little loss in the little circle for a little gain in the big circle. As it is, according to this particular graph (not 24" wide) the Sensitivity only falls off 2dB between 35 and 40Hz. Even with a slight reduction in that spot, I think I'd be alright with EQing flat down to 50Hz and leave the slope below that alone.

Also, I'm not sure how you guys look at an SPL chart. I initially looked at them as the higher the sensitivity at any point, the louder it is. However, assuming we've planned the system to have ample headroom, run below the limiter... after everything's all EQ'd to whatever your/my pleasure is, a single Db of sensitivity increase equates to a reduction of power needed to produce whatever level the music is being played at, whatever the arbitrary volume you or I deem as an appropriate level is. 1dB increase in sensitivity will require 89% of the voltage (or 79% of the watts) it would otherwise take to make the same SPL without the increase. 31.15V will make the same SPL as compared to 35Volts without the 1dB boost in sensitivity. 121 watts instead of 153. So, while we might not notice 1 or 2 dB with our ears, it isn't nothing. It puts us that much further away from a popped breaker. It could help with power compression losses. Avoid thermal buildup. Or, simply just add to the system headroom.

While some, most, or all of that may or may not be of valid concern in real world practice, it's where my mind is partially at in this project. I would love to be able to boast that I have the cleanest and loudest system on a single 15 amp circuit around my parts. The thought kinda tickles me a bit.

[Chris_Allen]

Having built both, I would always build the T39 due to their flexibility and size. However, the 3015LF is the best driver I've ever used. Such a shame there isn't something that can take a 15" that is around the same size as the T39. You can't have everything!

Because most of the venues I used to play in weren't very big, I couldn't use the subs below 50Hz anyway.

All said, I loved everything about my 30" 3015LF except moving them. Doors in the UK appear unnecessarily small when you move the T48s around.

[Bruce Weldy]

For me, it's such a close call between the two. As you guys are bringing up, it's not a super clean and clear decision. It's taken number crunching and soul searching to finally make a choice. In no way am I saying this choice is superior to the choice you guys made. It's just a different choice.

That's why you have to take in all the comments and weigh them carefully. Ultimately, you just have to pick one or the other. Most likely you'll love whichever you choose and like most of us, never hear the other box to truly compare.

[Seth]

Having built both, I would always build the T39 due to their flexibility and size. However, the 3015LF is the best driver I've ever used. Such a shame there isn't something that can take a 15" that is around the same size as the T39. You can't have everything!

Because most of the venues I used to play in weren't very big, I couldn't use the subs below 50Hz anyway.

All said, I loved everything about my 30" 3015LF except moving them. Doors in the UK appear unnecessarily small when you move the T48s around.

Thanks for sharing your experience Chris

I'd absolutely love to make some 36" wide 3015LF loaded T48's. The sensitivity is staggering, 102dB @ 40Hz... just awesome! With 4 of those, even though they can take up to 60 volts... shoot, feed them 30 and still get 135dB of 100% sustainable long term low end output. However, dimensionally, it's huge. I know you said yours were 30 wide, but I get it. I bet it makes any door slimmer than ideal. Which is sort of where I was at in thinking the 30" T39 over. Sure, slide it through sideways, or make it slimmer.

If your T39's were as wide as your T48's and your T48's as wide as your T39's... would that effect your opinion?

[Seth]

For me, it's such a close call between the two. As you guys are bringing up, it's not a super clean and clear decision. It's taken number crunching and soul searching to finally make a choice. In no way am I saying this choice is superior to the choice you guys made. It's just a different choice.

That's why you have to take in all the comments and weigh them carefully. Ultimately, you just have to pick one or the other. Most likely you'll love whichever you choose and like most of us, never hear the other box to truly compare.

You're probably right. At one point, I did consider making one or two of each out of OSB, test 'n trash... compare before committing to making a herd. Perhaps that's not a bad idea.

[Bruce Weldy]

You're probably right. At one point, I did consider making one or two of each out of OSB, test 'n trash... compare before committing to making a herd. Perhaps that's not a bad idea.

That's a whole lot of work, building two boxes you won't end up using....plus the cost of a driver that you'll end up not using...

If you truly need the extra 5hz of extension, then build the T48s. That's what it really boils down to.

Try this......take one of the subs you already have, hook it up to a driverack, play whatever song you think you need the extra extension for. Set the high pass at 40hz and listen. Now, raise it to 45hz and listen. If you don't hear a difference, then you don't need the extra 5hz. Most likely, whatever system you have been listening to doesn't really go all that low anyway.

[Seth]

You're probably right. At one point, I did consider making one or two of each out of OSB, test 'n trash... compare before committing to making a herd. Perhaps that's not a bad idea.

That's a whole lot of work, building two boxes you won't end up using....plus the cost of a driver that you'll end up not using...

If you truly need the extra 5hz of extension, then build the T48s. That's what it really boils down to.

Try this......take one of the subs you already have, hook it up to a driverack, play whatever song you think you need the extra extension for. Set the high pass at 40hz and listen. Now, raise it to 45hz and listen. If you don't hear a difference, then you don't need the extra 5hz. Most likely, whatever system you have been listening to doesn't really go all that low anyway.

I've tested high pass frequencies a bunch of times. It's pretty conclusive... I don't need it for live sound, but miss it for recorded content.


OSB's cheep, but not free... and it is a bit of work to just throw away. That's why I haven't done it. However, it'd be the same drivers I already have in either case. It's one of those things I should do, but really don't want to and probably wont.

[Bruce Weldy]

I've tested high pass frequencies a bunch of times. It's pretty conclusive... I don't need it for live sound, but miss it for recorded content.

Sounds like you've made a decision then. Time to make sawdust!

[Seth]

I've tested high pass frequencies a bunch of times. It's pretty conclusive... I don't need it for live sound, but miss it for recorded content.

Sounds like you've made a decision then. Time to make sawdust!

Yup yup. Heading to the lumber yard tomorrow.

[Bryan Cox]

I have my popcorn and bourbon ready. Eagerly awaiting the results!!!

[himhimself]

Best forum ever. Thanks all for your thoughtful posts and posits, and thanks for hosting, Bill

[AntonZ]

You're probably right. At one point, I did consider making one or two of each out of OSB, test 'n trash... compare before committing to making a herd. Perhaps that's not a bad idea.

You seem to have made up your mind already. I highly recommend you do what you suggested here though, but instead of OSB build both from decent ply. You wouldn't need to scrap two cabs, only one. That offsets the costs of the otherwise wasted OSB and you know for sure what you will get. You might even be able to sell the one cab you don't want to keep. Last but not least: when building a herd it is often recommended to build one cab to completion first. You learn as you build that one, then do the rest of the chosen model in parallel production style.