Have 1 FV15HP, what do I gain with 1 more? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 14 Old 04-08-2020, 08:05 PM - Thread Starter
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Have 1 FV15HP, what do I gain with 1 more?

Probably a rookie question, I’ve never had 2 subs before. I have a Ryhthmik FV15HP currently and am considering a second one, does the output and dynamics effectively double with 2? What are any other advantages of 2 subs over just 1 sub?

Thanks in advance
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post #2 of 14 Old 04-08-2020, 08:10 PM
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Quote:
Originally Posted by SD1290 View Post
Probably a rookie question, I’ve never had 2 subs before. I have a Ryhthmik FV15HP currently and am considering a second one, does the output and dynamics effectively double with 2? What are any other advantages of 2 subs over just 1 sub?

Thanks in advance
you will get a 5-6db increase when you colocate the subs, otherwise you will get a better frequency response across more seats if you separate the two but you won't get any increase in volume.

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post #3 of 14 Old 04-08-2020, 08:26 PM
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Quote:
Originally Posted by SD1290 View Post
Probably a rookie question, I’ve never had 2 subs before. I have a Ryhthmik FV15HP currently and am considering a second one, does the output and dynamics effectively double with 2? What are any other advantages of 2 subs over just 1 sub?

Thanks in advance

You can expect smoother frequency response at more seats, and 3-6db. It’s still important to find the best spots for them. Can’t just go Willy nilly.
So dynamics won’t double, but if you do it right, bass should be more consistent and effortless. Not that the fv15hp is a slouch.
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post #4 of 14 Old 04-08-2020, 08:31 PM
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You should get near 3dB overall increase in volume when spaced out, 6dB when together.

Should reduce localization, if any, and you might see an increase in dynamics due to you needing less power to reach the same spl.

You will get a more even bass response through multiple seating positions from more room modes (nulls and peaks) being cancelled.

Leave it at 8 ohms and call it a day :)
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post #5 of 14 Old 04-08-2020, 10:48 PM
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Quote:
Originally Posted by phatfreeza View Post
you will get a 5-6db increase when you colocate the subs, otherwise you will get a better frequency response across more seats if you separate the two but you won't get any increase in volume.
Properly set up (and not mutually coupled) you should still gain ~6dB OVERALL output (when measured with BW limited pink noise) when adding a 2nd identical sub. You will gain more at some frequencies and less at others

https://data-bass.com/#/articles/5cb...e58a?_k=9w0g6r

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post #6 of 14 Old 04-08-2020, 10:58 PM
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Originally Posted by jamiebosco View Post
Properly set up (and not mutually coupled) you should still gain ~6dB OVERALL output (when measured with BW limited pink noise) when adding a 2nd identical sub. You will gain more at some frequencies and less at others

https://data-bass.com/#/articles/5cb...e58a?_k=9w0g6r
good to know!

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post #7 of 14 Old 04-09-2020, 08:13 AM
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Originally Posted by Russdawg1 View Post
You should get near 3dB overall increase in volume when spaced out, 6dB when together.
I know I'm being pedantic, but...

If the dual-sub system is re-calibrated properly with the speakers, there will no increase in "volume." What there will be is an increase in system "headroom." IOW, there will be an increase in the maximum volume the system is able to achieve. Having said that, there will still be a very useful "volume" advantage to adding a 2nd sub; each of the subs will be calibrated at a lower output level. This will reduce driver excursion and amplifier power used at any given output level, both of which lower system distortion. A 3 dB decrease in level will reduce each of these parameters by HALF! This is really one of the biggest advantages of adding a 2nd sub. (One thing to note though... if the speakers are not up to an increase in maximum volume, the user will never get to experience the maximum increase in the volume of the subs. Nonetheless, the reduced distortion level is retained throughout the entire volume output range of the subs.)

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Originally Posted by Russdawg1 View Post
Should reduce localization, if any, and you might see an increase in dynamics due to you needing less power to reach the same spl.
In some instances, this reduction in localization can allow a higher crossover point, which may help with speaker/subwoofer integration.

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Originally Posted by Russdawg1 View Post
You will get a more even bass response through multiple seating positions from more room modes (nulls and peaks) being cancelled.
And this ^^^ is really the biggest advantage of adding a 2nd sub, especially if the two subs are widely displaced from each other, i.e., on opposite ends of the room from one another. This can result in significant null elimination, (one sub is flat where the other sub has a null, and vice versa.) Eliminating nulls fills in all the "missing" bass and makes all bass notes be audible. This improvement in bass "quality" can definitely result in the perception of "more bass" even without an overall increase in subwoofer output levels. (This can also result in more bass peaks, but peaks can easily be tamed with Room Correction/EQ, whereas nulls can't be corrected with EQ... adding more power to a null simply increases the null cancellation without increasing the SPL at the null frequency.)

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post #8 of 14 Old 04-09-2020, 08:24 AM
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My take. Added a second in the opposing corner of the room and even though my REW chart looked better the only "noticeable" improvement I heard was a little less localization. Not really a good bang for the buck...

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post #9 of 14 Old 04-09-2020, 08:50 AM
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if the second sub can fix a huge null....you will gain a ton of output where you filled in that null.


if what your asking is will 2nd matching sub will get you to next level in output I would say no, get the fv25hp. that will add like 10db in spl. thats what I did. I never listen that loud, but fv15hp got me max around 117db and with fv25hp and fv15hp max was 127db...all unscientific ofc, but close enough.

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post #10 of 14 Old 04-09-2020, 09:26 AM
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Quote:
Originally Posted by SD1290 View Post
Probably a rookie question, I’ve never had 2 subs before. I have a Ryhthmik FV15HP currently and am considering a second one, does the output and dynamics effectively double with 2? What are any other advantages of 2 subs over just 1 sub?

Thanks in advance
If you provide a sweep (rew + umik-1) of your room, we'd be able to answer your question specifically to your setup.

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post #11 of 14 Old 04-09-2020, 12:44 PM
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Quote:
Originally Posted by SD1290 View Post
Probably a rookie question, I’ve never had 2 subs before. I have a Ryhthmik FV15HP currently and am considering a second one, does the output and dynamics effectively double with 2? What are any other advantages of 2 subs over just 1 sub?

Thanks in advance

I know you are getting a lot of technical responses because you kinda asked a loaded question with a lot of determining factors. Based on my own personal experience, I started off with a single FV15HP and it was great, but when I finally added a 2nd it was just awesome. The seat to seat excitement throughout my >5,000 cu ft living room with vaulted ceilings was unreal. Running dual subs also takes a lot of the stress off a single sub. Just my 2 cents.....

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post #12 of 14 Old 04-09-2020, 01:51 PM - Thread Starter
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Originally Posted by JT78681 View Post
I know you are getting a lot of technical responses because you kinda asked a loaded question with a lot of determining factors. Based on my own personal experience, I started off with a single FV15HP and it was great, but when I finally added a 2nd it was just awesome. The seat to seat excitement throughout my >5,000 cu ft living room with vaulted ceilings was unreal. Running dual subs also takes a lot of the stress off a single sub. Just my 2 cents.....
Thanks for all the repsonses! I'd love to do the FV25HP or 2 of the FV18 but they just get to big for my space. I think I'll get another FV15HP, got my girfriend's approval so it certainly can't hurt right LOL.

Based on the consensus here I have to believe it will add a noticeable improvement in punch and dynamics over just 1 sub
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post #13 of 14 Old 04-10-2020, 05:56 AM
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I think you'll be happy with your results

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post #14 of 14 Old 04-10-2020, 07:37 AM
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Imo The best approach would be to measure the room response with REW of the single FV15HP. Take a base response measurement with no EQ(Audssey off), then perform a set of compression sweeps(with Audy on). If the OP is able to achieve a decent response and the sub exhibits no compression for his max listening levels, then a second sub isn't needed. If the response is pretty bad requiring a lot of EQ to flatten the response and/or he is driving the single FV15HP into compression on Movie night, adding a second sub would be very beneficial. There is no reason to guess at it when a 100.00 mic and downloading a freeware program will tell you if you need to invest another $1400.00 or not.
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