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PostPosted: Mon Nov 13, 2017 8:58 pm 
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I bought four 4ohm Lab15’s several years ago, and built 4 T48’s. I got a great deal on them because they were surplus parts from a special production run for a speaker manufacturer. I didn’t realize it at the time, but the specs for the special 4ohm version are different from the standard 6ohm model. I have been very happy with my subs, even though the 4ohm version of the Lab15 is a little “off spec” for use with T48’s. The output is less than the standard Lab15 in the same cabinet, but I don’t know how significant the difference is.

I bought another stack of wood and I am starting on 4 more T48’s. I can get more of the 4ohm drivers, but they have to be built in the Eminence custom shop. The final price is higher than the standard Lab15’s. Not a great idea.

I would like to use the standard 6ohm Lab15’s in the next 4 cabs, but I don’t know if the combination will have a negative effect on the quality or the volume of the sound. I checked some other Eminence drivers and the Definimax 4015LF appears to be closer to the specs of the 4ohm Lab15 than the 6ohm Lab15. The 4015LF has a lower Vd but the same Qts.

What specs should I worry about?
What are the side effects of different drivers?

Thanks for your help!

LostMindAgain


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PostPosted: Mon Nov 13, 2017 9:15 pm 
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LostMindAgain wrote:
What are the side effects of different drivers?



You might have to limit the 6ohm drivers to a different voltage than the 4 ohm driver.

_________________
Built:
17" width 10" driver Autotuba
2 x 29" width dual Lab12 Tuba60
6 x DR250 2510/asd1001
In progress:
2 x DR250 2510/asd1001
For best results, point the loud end of the array towards the audience


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PostPosted: Mon Nov 13, 2017 9:39 pm 
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I forgot to mention that the new subs will be on new/different amps. They can have their own gains and voltage limits.


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PostPosted: Mon Nov 13, 2017 9:46 pm 
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LostMindAgain wrote:
I have been very happy with my subs, even though the 4ohm version of the Lab15 is a little “off spec” for use with T48’s. The output is less than the standard Lab15 in the same cabinet.

I don't think this is right. AFAIK, output is the same, but the voltage displacement limit for the Lab15-4's is lower than the 6 ohm version.

I would like to use the standard 6ohm Lab15’s in the next 4 cabs, but I don’t know if the combination will have a negative effect on the quality or the volume of the sound.
It won't change the sound. Adding 4 cabs will increase volume by +6dB
I checked some other Eminence drivers and the Definimax 4015LF appears to be closer to the specs of the 4ohm Lab15 than the 6ohm Lab15. The 4015LF has a lower Vd but the same Qts.

The 3015lf, the 4015LF, and the 6 ohm Lab 15 all have identical voltage displacement limits, and the same volume.
Pricing (from speakerhardware) in the same order as above, is $200/215/285.
Save your money, use 3015lf's.


What specs should I worry about?
Don't worry about any, since you're looking at premium drivers already
What are the side effects of different drivers?
There may some marginal EQ changes required between the cabs, and the two types should be run on separate outputs on your DSP, with separate amps.

Thanks for your help!

LostMindAgain

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


Last edited by Grant Bunter on Tue Nov 14, 2017 3:02 pm, edited 1 time in total.

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PostPosted: Tue Nov 14, 2017 12:38 pm 
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[quote="Grant Bunter"][quote="LostMindAgain"]

The 3015lf, the 4015LF, and the 6 ohm Lab 15 all have identical voltage displacement limits, and the same volume.

Is that true? What about Xmax, Sd, and efficiency? Couldn't a driver have higher values of those, yet have a lower voltage limit on the vc? Or with higher values of all those, would manufacturers use a higher voltage coil?

IDK!

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2 DR250s, 2 27" Lab15 T-60s, 2 30" Neo Titan 39s, 1 Autotuba...and looking for more!


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PostPosted: Tue Nov 14, 2017 2:01 pm 
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I remember differing phase response between different (similar) drivers being mentioned as an issue. (specifically between the Eminence and Dayton drivers in an SLA pro) Is this an issue in a sub? Or are the waves long enough that minor differences aren't important?

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2xJ15, THT, 4xT39 3012 (2x15", 2x20"), 2xSLA Pro, 2x short SLA Pro (Dayton), W6


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PostPosted: Tue Nov 14, 2017 3:49 pm 
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Rich4349 wrote:

The 3015lf, the 4015LF, and the 6 ohm Lab 15 all have identical voltage displacement limits, and the same volume.

Is that true? What about Xmax, Sd, and efficiency? Couldn't a driver have higher values of those, yet have a lower voltage limit on the vc? Or with higher values of all those, would manufacturers use a higher voltage coil?

IDK!


Rich, there is a descending order of importance in factors/TS parameters, when assessing and calculating driver use/voltage displacement limits, in horn loaded cabs. The top 2 are Xmax and impedance. I'm not sure of the rest of the TS specs, and their descending order of importance, but Bill has said the top 2 are the most significant more than once.

BTW, the 3015lf has higher Xmax and Sd than the 4015lf, both have less than the lab15, but the lab15 is a 6 ohm nominal driver (8 ohm nominal for the other 2).
Start throwing in other variances in TS parameters, reducers for the lab 15 if used, and the three end up having the same voltage displacement limits, as listed in the plans, so output is the same.

This remains true despite the wildly differing power handling capabilities of each driver as well, because those stats are obtained in an infinite baffle, and not a horn. So it's not uncommon for a lot of drivers to reach Xmax and the drivers thermal limit at the same time in horn cabs.

Here's hoping I've got that right, but if I haven't, I'll learn something new today.

whines wrote:
I remember differing phase response between different (similar) drivers being mentioned as an issue. (specifically between the Eminence and Dayton drivers in an SLA pro) Is this an issue in a sub? Or are the waves long enough that minor differences aren't important?


Interesting. Phase response is dictated by the cab. While it's often enough said don't mix different types of cabs because of differing phase response (eg T39's and T48's) and the consequent induced frequency cancellations, I've not seen it said "don't use different drivers and mix them with other cabs" of the same design...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Tue Nov 14, 2017 4:09 pm 
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Grant Bunter wrote:
the three end up having the same voltage displacement limits, as listed in the plans, so output is the same.
The have the same voltage limits, but not the same output. The 4015 comes in last, due to the shortest xmax. The 3015LF is next, due to more xmax. The LAB 15 is the highest, having the longest xmax. The reason the LAB15 has the same voltage limit as the others is that it's a 6 ohm driver, which requires less voltage swing than an 8 ohm driver to reach the same excursion.


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PostPosted: Tue Nov 14, 2017 4:24 pm 
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Bill Fitzmaurice wrote:
Grant Bunter wrote:
the three end up having the same voltage displacement limits, as listed in the plans, so output is the same.
The have the same voltage limits, but not the same output. The 4015 comes in last, due to the shortest xmax. The 3015LF is next, due to more xmax. The LAB 15 is the highest, having the longest xmax. The reason the LAB15 has the same voltage limit as the others is that it's a 6 ohm driver, which requires less voltage swing than an 8 ohm driver to reach the same excursion.


Cheers Bill,
Today's learning!

So, can the value in extra output between the three be quantified?
Or is it near enough identical it's hardly worth mentioning?

And for the OP's question, should he purchase more lab15-4's, or????

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Tue Nov 14, 2017 4:42 pm 
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The difference spread between the three is maybe 3dB. I'd stay with the same driver if possible, otherwise probably with the standard LAB 15, but I don't know the specs on what he has so I can't be definitive.


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PostPosted: Tue Nov 14, 2017 4:47 pm 
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Bill Fitzmaurice wrote:
The difference spread between the three is maybe 3dB. I'd stay with the same driver if possible, otherwise probably with the standard LAB 15, but I don't know the specs on what he has so I can't be definitive.


Thanks!

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Tue Nov 14, 2017 10:44 pm 
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Bill Fitzmaurice wrote:
The difference spread between the three is maybe 3dB. I'd stay with the same driver if possible, otherwise probably with the standard LAB 15, but I don't know the specs on what he has so I can't be definitive.


In case you are intrigued and want to evaluate these drivers, or can give me insight into driver selection for the next batch of T48’s. The 4ohm drivers have more Xmax but higher Qts.

Re = 3.75
Le = 1.6
Qm = 3.76
Qe = .59
Qt = .51
Xmax = 13.02mm
Pmax = 600
Bl = 17.51
fs = 34.4
Mms = 221.2
Mmd = 207.6
Cms = .097
Rms = 12.714
Vas = 93.3
Sd = 823.7
Vd = 1072.3
EBP = 58.8
SPL = 90.0

By the way, I have 4 “ported” DR280’s with 3012HO’s and NSD-2005’s. They are amazing!
I love the sound I get from this setup. I just need more chest pounding bass.

Thanks again!


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PostPosted: Tue Nov 14, 2017 11:22 pm 
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Location: Ilfracombe Queensland Australia
Have you already got a price for custom made Lab 15-4's from Eminence?
I can't imagine a small custom order run is going to be cheap.

I just read back through all the posts you've made.
And you've been discussing cost from the outset.
Has that changed?

4 x regular Lab15's is going to cost you, based on retail pricing, $340 more than 4 x 3015lf's.
Output is greater sure, about 1dB per driver.

Something to consider.

You never did say, that I can see, how wide you built your cabs.
If you didn't build to maximum width, that might be an option too, to get more output...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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PostPosted: Wed Nov 15, 2017 6:09 am 
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Admittedly, I started this process several years ago with a serious “budget”. Since then, I have dropped thousands of dollars on amps, drivers, and materials. I am far less worried about money than I am about uniformity, output, and durability. The DR’s cost WAY more than the T48’s. I will probably roll with the std Lab15’s, unless there is a acoustic reason to choose another driver.

As for cab size, I have 4 32” T48’s and I was planning to build 4 more to keep them uniform. However, I have to buy a new trailer to haul all of this stuff, so the size on the cabs isn’t limited anymore. On the other hand, I am CDO (that’s OCD in alphabetical order). I have to maintain patterns and things like that.

If I change the cab size from 32” to 36” wide, does that cause any extension or phase issues?

Thanks

LostMindAgain


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PostPosted: Wed Nov 15, 2017 2:10 pm 
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Location: Ilfracombe Queensland Australia
LostMindAgain wrote:
If I change the cab size from 32” to 36” wide, does that cause any extension or phase issues?


No phase issues.
Normally, going wider would add output.
But going from 32" to 36" will probably be almost insignificant in that regard, so, in order to maintain your patterns, build the new cabs at 32" as well...

_________________
Built:
2 x DR 250 (melded array) with March 2012 plans.
4 x 20" BP102 T39's, 2 x 28" 3012lf loaded underway.
3 x WH8 with melded array.
Bunter's Audio and Lighting "like"s would be most appreciated...


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