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2 similar drivers in 2 different enclosures ?
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Old 22nd July 2019, 06:50 AM   #1
suparub is offline suparub
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Question 2 similar drivers in 2 different enclosures ?

Hi dear community I'm about to upgrade my 2 way system and I need to find a good balance between enclosure weight, frequency range and bass response.

I've been asking few questions and received amazing help on the forum so far. So on, to narrow down the project :

Drivers :
- 2 x Sub Drivers RCF LF15N401 - 15" Woofer
- 2 x Tops RCF ND840 - 1.4" Compression Driver

Subs Enclosures :
THAM15 (for bass response) + Vented (for linear frequency response after 200Hz).

My question :
Is this a good idea to build one THAM15 for a sub driver, and one Vented for the other sub and link them in parallel vs building 2 vented or 2 THAM15 enclosures?

As it's a 2 way system, I need to be sure that the frequencies between 200HZ and 800Hz will be well covered by the bass drivers, this is why I'm pretty sure I need at least one vented enclosure. At the same time, I would love to get the bass efficiency of a tapped horn enclosure as the THAM15.

From my understandings, the crossover should be set at 800Hz.

Here is what should look the bass driver in the THAM15 (kudos to freddi <3 )
vUMN98N.png

Here is what should look the bass driver in a vented enclosure (I've done it myself, if you have any tip to improve the max SPL or linear response after 200Hz, I would be happy to know)
LN Vented.JPG

Thanks in advance for the help !
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Old 22nd July 2019, 09:37 AM   #2
suparub is offline suparub
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Edit : I am also thinking switching to midbass drivers in order to reach these 700 / 800hz with the sub enclosures, so it's also an option : RCF MB15N401 - 15" Mid Bass
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Old 22nd July 2019, 09:50 AM   #3
bjorno is offline bjorno  Sweden
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Hi suparub,

vUMN98N.png Warning: This Picture is telling nothing of the eventual built Performance of the Tham Sub as the totally random non logical HR Pictures of this HR-Tombola run only show ignorance(especially the FR Plots when no clogging Losses are included and non existing (Timing)Phase info) of Quarter-wave summing of two in Time separated Transfer Functions that would give a clue on how to to sum with minor Amplitude/Phase flaws if attempting to build a System.
This Forum is totally littered with clue-less(IMO useless) random Tombola-run HR pictures followed by ignorant Technobabble because lack of Math and Acoustics Knowledge on how to interpret HR Quarter-wave Graphs.
Note : A Complete set of HR Graphs is way over the heads of most diyAudio Members, never accuse HR to be incomplete.

b
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Old 22nd July 2019, 04:42 PM   #4
weltersys is offline weltersys  United States
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Quote:
Originally Posted by suparub View Post
My question :
Is this a good idea to build one THAM15 for a sub driver, and one Vented for the other sub and link them in parallel vs building 2 vented or 2 THAM15 enclosures?

As it's a 2 way system, I need to be sure that the frequencies between 200HZ and 800Hz will be well covered by the bass drivers, this is why I'm pretty sure I need at least one vented enclosure. At the same time, I would love to get the bass efficiency of a tapped horn enclosure as the THAM15.

From my understandings, the crossover should be set at 800Hz.
No, linking a TH and BR cabinet for parallel use to 800 Hz is not a good idea.
As Bjorno has already explained in his own inimitable way, due to the massive phase and frequency response differences between a ported and a TH enclosure, mixing them for the same range up to 800 Hz would not provide a good response in either the lower or upper range you want to use them, 40-800 Hz (over four octaves).

The TH can provide decent response for a few octaves, if you want it to sound decent at 800 Hz, the low end would be limited to around 200 Hz.

A pair of BR would be a better choice than mixing the TH and BR.

Better yet would be a three-way two box system, if you wanted to limit the amp channel count, a passive crossover at around 800 between the front-loaded mid and high driver. That said, with as inexpensive as amplification and DSP are, better to go three way.

Last edited by weltersys; 22nd July 2019 at 04:46 PM.
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Old 22nd July 2019, 06:57 PM   #5
suparub is offline suparub
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bjorno I love you XD
weltersys thank you for translating this high level post to a most "basic" language.

I ditched the 3 way option as I really need to be light and low in consumption, but now you are putting it again on the table, my amp is driving 1600W per channel in 2 ohms, so I could add to the 2 LF15N401 900W (already in // and at 4 Ohm each in this configuration) 2 x 300W midbass driver RCF MR10N301 - 10" Sealed Basket . This would give a resistance of 2ohm on each woofer/midrange driver

The questions that arise now are :
- Is sending a 40Hz - 700/800Hz signal to the MR10N301 will damage them ?
- Do I need a limiter for the 300W MR10N301 in order to not blow them as the subs can support up to 900W continuously ? If yes how ?
- A question that I always asked myself without really finding an answer : adding more speakers in parallel to an amp channel will consume more electric power or it will stay the same ? Consumption is very important in my case. My guess is no because from what I understood, the amp will deliver the same amount of power, only the resistance change but I may be wrong

BLESS

Last edited by suparub; 22nd July 2019 at 07:26 PM.
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Old 22nd July 2019, 08:18 PM   #6
weltersys is offline weltersys  United States
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Quote:
Originally Posted by suparub View Post
1)- Is sending a 40Hz - 700/800Hz signal to the MR10N301 will damage them ?
2)- Do I need a limiter for the 300W MR10N301 in order to not blow them as the subs can support up to 900W continuously ? If yes how ?
3)- A question that I always asked myself without really finding an answer : adding more speakers in parallel to an amp channel will consume more electric power or it will stay the same ?
1) Damage to a speaker is either thermal, as in a burnt voice coil- blistered former or melted adhesives, or mechanical- torn, kinked or smashed parts. Depending on the amplitude (voltage level) and frequency of the signal, you can damage the MR10N301 in either fashion.
2) Limiter protection requirements are quite different to protect low, mid, and high drivers. As to "how", that requires separate peak and RMS limiters and HP and LP filters appropriate for the pass bands, excursion, peak and continuous potential of each component.
3) Depending on the amplifier's design, more speakers in parallel to an amp channel will generally consume more electric power. If the amp has no current limiting, doubling drivers will double the power used, however, two LF cabinets (of the same design) will be 3 dB more sensitive than one, so require only half the amp power to achieve the same output level.
Since a TH may be 6 dB more sensitive than a BR, power consumption could be reduced by 4 times by using them instead.
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Old 22nd July 2019, 08:29 PM   #7
suparub is offline suparub
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thanks again weltersys, I'll sleep on that ^^ (literally XD)
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Old 23rd July 2019, 07:35 PM   #8
suparub is offline suparub
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Here we go for a vented enclosure that will host the two drivers : http://www.lean-business.co.uk/SPEAK...L%20REFLEX.pdf

About the drivers choice, should I go with RCF LF15N401 - 15" Woofer or RCF MB15N401 - 15" Mid Bass ? My goal is the most linear response from 40Hz to 20Khz in a 2 way system crossing at 800Hz
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Old 23rd July 2019, 07:54 PM   #9
suparub is offline suparub
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I just "simed" the two drivers into BassPro and wow, the 2 MB15N401 are doing much better than the 2 LF15N401, even at low frequencies. Are my predictions alright ?

SoundSystem.JPG

Last edited by suparub; 23rd July 2019 at 08:08 PM.
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Old 23rd July 2019, 09:02 PM   #10
suparub is offline suparub
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Strange thing, when I tried to model the same box with the 2 drivers on WinISD it gave me different sims, much more close to each other.

winisd.JPG

The Truth is Out There ^^ but where ?
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