DR build questions

[Bill Fitzmaurice]

Minor threadjacking: would building a 48" flared section for the mouth of a 24" wide Titan increase performance any? Maybe a few dBs at the lower cutoff?

If you need to go lower than V plated T48s will go build T60s.

[Rich4349]

If you need to go lower than V plated T48s will go build T60s.

Not lower than 40/45: louder at 40/45.

[Bill Fitzmaurice]

Same answer.

[Keryn O'Shea]

You might look into 3D printing some washers of the required thickness for spacers..

Great idea man, we're seeing more people using 3D printers here. I wonder if a felt backed spacer would end up sticking to the Duratex..?

the size of that T48 says it means business. Verrrrry nice

Yes, l can't read plans properly so l cut all the panels at 36", so it's a 37" T48! I'm lucky l have long arms, because l struggled driving screws into panel 9, l was up to my neck in the horn

...go build T60s.

Yep, they're next! Just need to find one more LAB15 to build 4

Here's a conveniently accidental mobile saw table for when l'm on a chopathon away from the house

[Keryn O'Shea]

Which frequency is the 2.83v set at before measuring cabs for an SPL chart? Is it 30hz for subs, 1khz for tops?

[Bruce Weldy]

Which frequency is the 2.83v set at before measuring cabs for an SPL chart? Is it 30hz for subs, 1khz for tops?

It's not "a" frequency - it's all frequencies - typically pink noise.

[Bill Fitzmaurice]

You can't get a constant 2.83v with pink noise as the signal flutters. You take the reading with the voltage in the vicinity of 2.83v, then you take a reading in the middle of the passband with a sine wave at 2.83v. That would be around 60Hz with a sub, 500Hz with a top. That gives you a number to calibrate the full chart to.

[Keryn O'Shea]

Excellent, thank you very much

[Keryn O'Shea]

I'd forgotten how the second cab of something new builds itself! The KL3015CX was dropped into the second T48 last weekend and given 35v @ 30hz, l feel nothing was lacking in comparison to the 3015LF at that level. I'll crack on with the other 2 subs and DR as l'm still trying to wrap my head around measuring cabs, then creating an SPL chart, over the Xmas break there'll be time to sit down and go through it. I'm eager to measure the DR as l felt l had to use too much eq.. although l was only 3 feet away at a very low level listening that day. I dont have a brains trust on speed dial anymore, though I'm keen to be able to produce them, and I'm sure once l have time it'll become more clear.
These T48s will all be built to handle LAB15s, would there be a noticeable increase in output loading them?
Really looking forward to hearing how this bucket list system sings..

[Seth]

I'd forgotten how the second cab of something new builds itself!...

That's awesome, Keryn! I love seeing them done in somewhat knotty construction grade pine ply too.

...l'm still trying to wrap my head around measuring cabs, then creating an SPL chart...

Measuring the system is the key to tuning it. Once you've got a base tune dialed in, you can usually tweak it by ear, venue to venue. Or measure every time. I prefer to measure every time, but time and interest are not always abundant. Most times, the base tune is completely adequate.

Measuring to create sensitivity response charts is only a few more steps to get it done well enough to be used as a general comparison to other 1W/1M charts. When it comes time to dive into it, it might be best to start a dedicated thread for measuring and creating response charts.

...These T48s will all be built to handle LAB15s, would there be a noticeable increase in output loading them?...

Between the 3015LF and LAB15, you may be able to measure an increase in output with the LAB15, but you're not likely to hear a noticeable difference in peak output unless you A/B them side by side, it would only be 1-2 dB. Any difference in output potential would only occur when the signal is being suppressed by the limiter. Any level of output less than that is identical. So, as long as you're not constantly bumping into the limiter, you'll never know the difference. If you are constantly bumping into the limiter, you need more cabs.

3015LF is always recommended over the LAB15 in a T48 unless there are other factors involved, such as availability/delivery issues or maybe if the cabs are intended for a permanent install that never/rarely get's moved to other locations.

...These T48s will all be built to handle LAB15s...

Is this implying that you're constructing them with the chamber reducers?

[Keryn O'Shea]

That's awesome, Keryn! I love seeing them done in somewhat knotty construction grade pine ply too.

Thanks mate, one day I'll pull the trigger on BB, it's $170au a sheet here atm! And our ply measures 1220x 2440mm so you only get one T48 side a sheet! I had dreams of making T47s, but Grant talked me out if that.

..When it comes time to dive into it, it might be best to start a dedicated thread for measuring and creating response charts.

Excellent idea, which part if the forum?

Between the 3015LF and LAB15, you may be able to measure an increase in output with the LAB15, but you're not likely to hear a noticeable difference in peak output unless you A/B them side by side, it would only be 1-2 dB.

Ok great, that satisfies my curiosity, and saves me wasting time, the LABs will wait for T60s

...These T48s will all be built to handle LAB15s...
Is this implying that you're constructing them with the chamber reducers?

Yes, and double driver anchors, so the LABs could go in if they had to.. but I'll set limiters like a good boy should, l had thoughts of the LABs outperforming 3015LFs at that point. I feel lucky and grateful for finding and being able to modify the KL3015CXs, otherwise l would be loading LABs in two of the T48s

[Seth]

..When it comes time to dive into it, it might be best to start a dedicated thread for measuring and creating response charts.

Excellent idea, which part if the forum?

That's a good question. Hmm. Seems it could just as well go in Everything Else, Pro Sound setup, or the DR section (Tuba/Titan if measuring those). Might even work well in the Reviews section too.

Unless Bill makes a recommendation, start the conversation wherever you feel is best.

[Keryn O'Shea]

Great day for it lads, had time to do a bit this weekend, the piezo module kicked my butt last time.. we'll see how round 2 goes. Not including the finish & tune, feels like I'm over half way there. Hope you guys are doing well, cheers

[Seth]

Great look'n birdhouse you've got there

[Keryn O'Shea]

Great look'n birdhouse you've got there

Mate it could double as one atm! Now l can't unsee that though, thanks very much