Scaling way back! Lots of questions

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Grant Bunter
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Re: Scaling way back! Lots of questions

#61 Post by Grant Bunter »

Something is funky with the charts Seth.
In order for the top chart to be apples to apples, both the T39 and T48 traces need to have the same 18 inch width, then +6dB can be added to both traces for 2 cabs.
I get that you took the 4 x 14" S2010 trace from the Labsub comparison in the T39 SPL charts section, and there's not really any ready done SPL charts to allow that, but for the purpose of demonstrating the difference, using a 20" wide S2010 loaded T39 chart would be close enough.

Then, with the second chart, the S2010 in the T39 has a limit of 27V, or +20dB at max (The +20dB S2010 figure is derived from the T39 charts page).
The T48 with a 3015LF is going to be perhaps a tad more than +26dB max with it's 60V limit (since a 56V limited 3012lf in a T39 is +26dB at max).

Or a single 20" wide S2010 chart and an 18" wide T48 chart together, then add +26dB and +32dB respectively to compare each x 2 cabs.

I haven't and don't use the SPL charts tool, but with a chart done with the above in mind, it wouldn't surprise me at all if the T48's won the day...
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...

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Seth
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Re: Scaling way back! Lots of questions

#62 Post by Seth »

Grant Bunter wrote: Wed Jun 02, 2021 5:25 pm Something is funky with the charts Seth.
In order for the top chart to be apples to apples, both the T39 and T48 traces need to have the same 18 inch width, then +6dB can be added to both traces for 2 cabs.
I get that you took the 4 x 14" S2010 trace from the Labsub comparison in the T39 SPL charts section, and there's not really any ready done SPL charts to allow that, but for the purpose of demonstrating the difference, using a 20" wide S2010 loaded T39 chart would be close enough.
Either I'm not understanding your point, I wasn't clear enough about the numbers in the previous post, or you misunderstood his question... He specifically asked about 4 slim T39's KL3010LF loaded compared to 2 18" T48's, 3015LF loaded (similar pack space). Why would we want to model a 20" T39 if he's interested slims?

Since the only T39 slim(ish) chart is with the S2010, that's the closest reference to use. +12dB on the T39 to account for 4 cabs @ 2.83v. +6dB on the T48 to account for 2 cabs @ 2.83v.

Then, with the second chart, the S2010 in the T39 has a limit of 27V, or +20dB at max (The +20dB S2010 figure is derived from the T39 charts page).
The T48 with a 3015LF is going to be perhaps a tad more than +26dB max with it's 60V limit (since a 56V limited 3012lf in a T39 is +26dB at max).

Or a single 20" wide S2010 chart and an 18" wide T48 chart together, then add +26dB and +32dB respectively to compare each x 2 cabs.

I haven't and don't use the SPL charts tool, but with a chart done with the above in mind, it wouldn't surprise me at all if the T48's won the day...
In the second charts we're pretending the 10" drivers are KL3010LF's, which have a voltage limit of 50v. I did actually make a mistake and ran the numbers based on a 45v limit though.

Here they are again, 50v KL3010LF T39's x4 and 60v 3015LF T48's x2, along with the breakdown. By the way, the charts are just in the charts tool and +dB are manually added. Here's the thread on how to use the charts tool. For easy access/reference I have the page linked in my signature. See that last little "1" in the MCM part number? There it is. Sneaky little secret quick reference link.

So for the slim T39's it's base plus 6 to account for doubling to 2 cabs and another 6dB for doubling again to 4 cabs, totaling +12 for the 4 cab count.
50 volts @ 8ohm is 312w which equates to +24.9dB (25dB) power gain.
25+12= +37dB

For the Pair of T48's, +6 for 2 cabs
60 volts @ 8ohm is 450w... 26.5dB power gain
26.5+6= +32.5dB total gain above the charts native 2.83v trace.






Side note: the 14" T39's in these charts are actually 1" wider than the slimmest T39 in the current plans. So, there's another slight inconsistency in the traces in the chart above; it's not actually KL3010LF loaded and it's an inch wider than a slim. Ultimately just a rough idea what to expect.
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

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Seth
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Re: Scaling way back! Lots of questions

#63 Post by Seth »

J_Dunavin wrote: Wed Jun 02, 2021 9:00 am ...
I wonder How four slim T39s would compare loaded with the kappa pro 10lf?
Oops... not KL3010LF's. Kappa Pro 10LF's, which have a 45v limit in the T39. KL3010LF's are 50v.

4 of either in slim T39's will trump 2x 3015LF 18" T48's in combined voltage sensitivity and peak output at the bottom of the bandwidth by a fair margin.
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

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Seth
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Re: Scaling way back! Lots of questions

#64 Post by Seth »

Oh! And BTW Joe, Amazon is still showing that they have 16 of the discontinued Delta Pro 8 drivers in stock if'n ya wanted them for some OT8 builds.
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

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J_Dunavin
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Re: Scaling way back! Lots of questions

#65 Post by J_Dunavin »

Bill has mentioned before that these do work best in multiples... that’s why I was thinking 4 slims, of something. My 18” wide T45s were tough enough going up and down steps, not so sure I want to try a T48 in that width.
Maybe I just needed better handle placement.
Oh I also see in the plans I could go as slim as 15 inches with a 3012lf in the T48....
Ugh I need to make some cardboard mock ups..
Thanks for the help guys. Trying to think up a very mobile friendly rig that won’t take up a considerable amount of pack space.

Oh thanks for the heads up on that... yes Otop 8s are definitely a go! Was just waiting on selling the other stuff 1st.... and maybe wait for these lumber prices to come back to normal 🤷🏻‍♂️
2 - OTop8
2 - T39
8 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

Grant Bunter
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Re: Scaling way back! Lots of questions

#66 Post by Grant Bunter »

Seth wrote: Wed Jun 02, 2021 8:36 pm He specifically asked about 4 slim T39's KL3010LF loaded compared to 2 18" T48's, 3015LF loaded (similar pack space). Why would we want to model a 20" T39 if he's interested slims?
Grrrr damn ads, I had to re read the entire thread to find the question about the 4 slims under an ad :cussing:
( I know the ads are necessary)

In post 1 page 1 it was about a pair of T39's or T48's.
That's why I was going with a 20" wide T39.

Interestingly, when the 3010LF came out, the voltage pre modelling was predicted as probably being 55V, very similar to the "old" voltage limit of the 3012LF at 56V in the charts section for +26dB.

While it's an intriguing question within itself, the charts are raw charts. They don't account for the limitations stated in the plans.
HP for 2 x t48's is 40Hz, 4 x T39's 45Hz.
So, if content is part of the equation, then, at 40Hz, the 4 x T39's, with a 24dB/octave slope at 45Hz, will be at least -6dB compared to the value at 45Hz, which should mean, based on a chart visual only, that the advantage goes to the T48 at 40Hz (by roughly 2dB).

Starting to look into cost (if that's also a consideration) 2 x 3015LF's are cheaper than 4 x 3010lf's, less ply, less cab corners/Speakons/plates/wheels and paint, for similar output/faster build.

Given J's most recent post, 2 cabs Vs 4 up stairs and from a mobility point of view (even if they are only a few inches wider at 18") is still also more appealing than 4 of anything for bottom end...
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...

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J_Dunavin
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Re: Scaling way back! Lots of questions

#67 Post by J_Dunavin »

Sorry guys I’m all over the road 😄
I just need to make some cardboard mock-ups and see how they fit.

Yaaa I dislike the adds too, but I’ll deal with them.
2 - OTop8
2 - T39
8 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

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Seth
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Re: Scaling way back! Lots of questions

#68 Post by Seth »

99% of the time I'm on PC/Chrome and I use the Ad Blocker Plus Add-On in Chrome. Zero ad's most of the time. No annoying countdown ads or mid video ads on YouTube videos. No ads here on this site either. When I use my phone for this site or YouTube... I'm like WTF??? :shock: It's absolutely amazing and almost sickening how obtrusive and borderline deceptive the ads are worded and placed. If I could just figure out how to get ad blocker plus on my phone...


T39/T48 High-pass settings are:
T48 40Hz less than 4 cabs, 35Hz 4 cabs or more
T39 45Hz less than 4 cabs, 40Hz 4 cabs or more

2x T48's and/or 4x T39's have the same high-pass setting, 40Hz.
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

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Seth
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Re: Scaling way back! Lots of questions

#69 Post by Seth »

J_Dunavin wrote: Wed Jun 02, 2021 10:08 pm Sorry guys I’m all over the road 😄
I just need to make some cardboard mock-ups and see how they fit.
I'm searching for a pic I saw a few days ago that came up in a google photo search. It was a T48 next to a T39. It didn't say what the widths were, but they looked to be about as wide as they were deep. So, roughly 20" for the T39 and 24" for the T48.

The T48 absolutely dwarfed the T39. I'll post it if I can find it again. Can't remember what I was searching when it came up :wall:
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

Grant Bunter
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Re: Scaling way back! Lots of questions

#70 Post by Grant Bunter »

Seth wrote: Wed Jun 02, 2021 10:26 pm T39/T48 High-pass settings are:
T48 40Hz less than 4 cabs, 35Hz 4 cabs or more
T39 45Hz less than 4 cabs, 40Hz 4 cabs or more

2x T48's and/or 4x T39's have the same high-pass setting, 40Hz.
Sorry, yes you're right there.
I think if you're going to bother to build 4 cabs though, you may as well load them with the KL3010LF, given that by going slim you lose the benefit of free output gained by making the cabs wider.
By once cry once and all that...
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...

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Seth
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Re: Scaling way back! Lots of questions

#71 Post by Seth »

Grant Bunter wrote: Thu Jun 03, 2021 2:21 am ...I think if you're going to bother to build 4 cabs though, you may as well load them with the KL3010LF...
+1, absolutely. :thumbsup: +3dB over BP102's and less weight. I can't think of any reason to go with the Kappa Pro 10LF, unless it's a permanent or semi-permanent installation.
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

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netwerks
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Re: Scaling way back! Lots of questions

#72 Post by netwerks »

4x16" t39 with 3012lf will make one hell of a racket. Using auracoply they are really light. The 16" cab is the minimum size so you don't have to do the alternative driver access panel build that a 15" would require.

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AntonZ
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Re: Scaling way back! Lots of questions

#73 Post by AntonZ »

I know you made up your mind on the OT8's already, just wanted to drop my 2c on the SLA's. I would think they play loud enough for your intended audience size. Easy build, easy carry, versatile pack space. Last but not least their slender shape makes them less obtrusive to the corporate and bridezilla eye. For the latter the white option (no matter what model tops and subs you build) as mentioned before would be totally brilliant. It matches her dress. What's not to like.

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J_Dunavin
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Re: Scaling way back! Lots of questions

#74 Post by J_Dunavin »

Ok guys finally found that T39/48 picture. I know these are much wider that i plan on, but ... woah that is a difference.
viewtopic.php?f=13&t=17112


I had put some serious thought into the SLAs. I’m sure they would be loud enough and the size, form factor sure is appealing, but I’m really comfortable with the wood working and now were talking cost vs performance, with the extra drivers. Besides, the OT8s are small enough to fit in the wife’s Buick Enclave ;)
2 - OTop8
2 - T39
8 - DR200
2 - DR250
9 - T24
6 - T45
1 - Auto Tuba

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Seth
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Re: Scaling way back! Lots of questions

#75 Post by Seth »

Yes! Exactly the one I was looking for! Spent fruitless hours looking for that last night. Glad you found it so I can rest my mind.
T48-5.jpg
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

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