Author Topic: Subwoofer  (Read 315 times)

Offline spm3

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Subwoofer
« on: September 11, 2017, 06:48:30 AM »
Hey guys,

I am looking into getting matched pairs for my musical subs.
Right now I have a REL R-505. I bought it used, and it was the top of the line model of that R series.

From the research I've done, my understanding is that it is best for the second subwoofer to be the same exact model as the first. So I would have to find another R-505 (which will be very very difficult!!!).

I have 3 options:
1) Wait for a very good condition used REL R-505 to come on sale somewhere
2) Get a sub that's very similar to the R-505 - R-528 or the S/5 SHO
3) Sell my REL R-505 and get a matching pair of a newer model subwoofer whether it's a REL like the ones above (R-528 or the S/5 SHO), or another subwoofer that's similar in quality.


What do you guys think I should do?
What are subwoofer brands are really high end and great for music listening?
Anyone got a REL Acoustics R-505 I can buy?!? lol


Thanks,
Shawn

Offline rollo

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Re: Subwoofer
« Reply #1 on: September 11, 2017, 08:18:30 AM »
  If room is not an issue I know of no better subs then OB "H" frame. Using GR Research drivers and Rythmik amps. About a $1500 investment if you DIY. The Swarm by Duke is something to look into as well.


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Offline richidoo

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Re: Subwoofer
« Reply #2 on: September 11, 2017, 02:08:54 PM »
I disagree they have to be the same. If they play up high crossing near 300Hz then yes, they need to be the same, and in placed under the main speakers in stereo. But that's usually called a woofer, not subwoofer which is usually <80Hz. If you're just playing to 80hz or lower, they don't need to be the same. There isn't so much tonal information down there, mostly just fundamentals, which is why we can tolerate subwoofers with THD of 10% and it still sounds good. Try that with a tweeter where all the harmonics are that determine tone quality, and where 0.1% THD is intolerable. 

Exspurts say that having subs of different designs and placed randomly around the room (electronically time delayed to match 1st arrival time of the main speakers) is the best way to minimize acoustic modes in the room.

IMO, the best subs for "high-end" music listening will have very large cone, large powerful motor, large sealed sturdy cabinet with lowish Qts like .57, very high power and high damping amplifier - and having many of them (to increase total cone area and minimize cone excursion and distortion at given volume level.) Bass is by far the most difficult and expensive register to execute well in a home stereo system, but it offers the most valuable opportunities for upgrades.
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Offline mresseguie

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Re: Subwoofer
« Reply #3 on: September 11, 2017, 05:04:58 PM »
Shawn,

I'm chiming in with the above two posts. Charles' three options are excellent. I own one Rythmik F12G sub. I've heard the GR Research OB subs four times, so I know they're great. I've never heard the Swarm, but they're well known and reviewed.

I agree with Richidoo on using different subs if they're plying <80Hz. Same subs, different subs, different sizes.....all okay.
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Offline doug s.

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Re: Subwoofer
« Reply #4 on: September 11, 2017, 05:27:52 PM »
if it were me, i would personally look for subs that were actually flat to <20hz.  all i could find about this model is that it's -6db at 12hz in-room.

john casler has a pair of vmps largers he's selling; you would need outboard x-over and amp/s.
http://www.usaudiomart.com/details/649377787-two-vmps-larger-subs/

i would also investigate seaton sound, jtr and powersound audio.

and i agree that if the x-over point is low enough, different brand/model won't be such a big deal, as long as the quality and low frequency range is equivalent.

doug s.

Offline rollo

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Re: Subwoofer
« Reply #5 on: September 12, 2017, 08:12:22 AM »
 To date the best implementation of multiple subs was at Scottys' home. Scotty your input here would be appreciated.


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Offline doug s.

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Re: Subwoofer
« Reply #6 on: September 12, 2017, 01:18:46 PM »
To date the best implementation of multiple subs was at Scottys' home. Scotty your input here would be appreciated.


charles
you mean the best you've heard, right?  ;)

doug s.

Offline Folsom

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Re: Subwoofer
« Reply #7 on: September 13, 2017, 09:56:29 AM »
My mods take the Rhythmics to another level, for OB H frames etc.

Offline spm3

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Re: Subwoofer
« Reply #8 on: September 13, 2017, 11:54:35 AM »
Okay, thanks for all your responses.
I spoke to the REL dealer of NE America, and he said they should be at least the same in driver size.
The REL R-505 has a 12" driver, and he said the ones that are similar will have the same size driver.
Those are: Q-401, R-505, R-528, or S/5 SHO

So he said keep an eye out for them on the used market or buy the new one, but he said it would be hard to match them with a different brand because it's like having 2 different brands of main speakers (or even different versions of the main speaker). You wouldn't do that with your speakers, so you shouldn't do that with your sub.

My main speakers frequency response is 43 Hz 23,000 Hz 3dB
I have my current sub being crossed over at around 53hz.

Offline doug s.

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Re: Subwoofer
« Reply #9 on: September 13, 2017, 03:44:34 PM »
oooh - serious typo here - the rel r505 is -6db at 21hz, not 12hz.  if it were 12hz, i would not be suggesting replacing it!  ;)

doug s.
if it were me, i would personally look for subs that were actually flat to <20hz.  all i could find about this model is that it's -6db at 12hz in-room.

john casler has a pair of vmps largers he's selling; you would need outboard x-over and amp/s.
http://www.usaudiomart.com/details/649377787-two-vmps-larger-subs/

i would also investigate seaton sound, jtr and powersound audio.

and i agree that if the x-over point is low enough, different brand/model won't be such a big deal, as long as the quality and low frequency range is equivalent.

doug s.

Offline _Scotty_

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Re: Subwoofer
« Reply #10 on: September 13, 2017, 05:44:51 PM »
I use two extra subs to flatten out the bass response in my room. I am crossing over at 125hz at 24db/oct with a Bessel function filter instead of the default Butterworth filter. The pro-fi digital crossover I am using is a QSC DSP-30 and has up to 8 stereo presets possible.
 I set it up to give a delay equal to 12ft. for the right ch. and 15ft. for the left ch. with the subs connected 180 degrees out of phase with the front speakers. The objective is to cancel out the bass from the front speakers before it hits the rear and side walls of my L shaped room and creates standing waves and bass response irregularities.
 However, due to L shaped room I may have 60% effectiveness at best. I do have fairly flat response at the listening position, around + or - 4db between 115Hz and 20Hz and 3db down at 18Hz. If the room was cubical or rectangular I might have better than 75% effectiveness with maybe + or - 3 dB throughout the room.
 L shaped rooms are a curse and very difficult to deal with on a number of fronts. I am hoping for a conventionally shaped room in our next home.
Scotty 

Offline doug s.

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Re: Subwoofer
« Reply #11 on: September 13, 2017, 07:25:23 PM »
you're running your mains full range?  why not cross them over?  if the x-over is reasonably transparent, any negatives from running the mains thru it will be more than compensated for by the speaker not having to output the lowest octave.  and, you could also try a lower x-over point.  the only time i had success w/a x-over point at 125hz was w/one particular pair of speakers whose bass response was extremely loose and exaggerated, perhaps to make up for not having a lot of "real" low bass.  my vmps largers were actually tighter and cleaner than those speakers, at 100-125hz.  even my tiny proac tablette 8 sigs liked being crossed over at ~80hz, and they would go loud that way, in a 26x38x8.5 room.

doug s.
I use two extra subs to flatten out the bass response in my room. I am crossing over at 125hz at 24db/oct with a Bessel function filter instead of the default Butterworth filter. The pro-fi digital crossover I am using is a QSC DSP-30 and has up to 8 stereo presets possible.
 I set it up to give a delay equal to 12ft. for the right ch. and 15ft. for the left ch. with the subs connected 180 degrees out of phase with the front speakers. The objective is to cancel out the bass from the front speakers before it hits the rear and side walls of my L shaped room and creates standing waves and bass response irregularities.
 However, due to L shaped room I may have 60% effectiveness at best. I do have fairly flat response at the listening position, around + or - 4db between 115Hz and 20Hz and 3db down at 18Hz. If the room was cubical or rectangular I might have better than 75% effectiveness with maybe + or - 3 dB throughout the room.
 L shaped rooms are a curse and very difficult to deal with on a number of fronts. I am hoping for a conventionally shaped room in our next home.
Scotty

Offline _Scotty_

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Re: Subwoofer
« Reply #12 on: September 13, 2017, 09:53:05 PM »
Here is an image of the full range speakers/cat tree used in my system.

They're flat to 18Hz on their own, no equalization is used in the system other than the extra subs.
About 95dB 1watt/1 meter sensitivity.
In most residential listening rooms the Schroeder frequency below which the room starts behaving as a resonator falls between 100 and 200Hz, frequencies below about 125Hz in my room exhibit response variations, hence the relatively high Xover frequency. The subs are being operated about 20dB or more below the SPL of main loudspeakers output. Their effect isn't really noticeable until they are turned off.
  In order for effective suppression of room resonant nodes to occur via phase cancellation one must have sources of bass frequencies at both ends of the listening room. Here is a link to the short version of the paper on which my setup is based.
http://vbn.aau.dk/files/62729209/LF_sound_field_control.pdf
And a link to the long version where the problems endemic to an L shaped room are discussed at the end of the paper. http://vbn.aau.dk/files/12831869/AC-phd.pdf
 I neglected to mention that Xover has a 24/48 ADC/DAC chip and sucks above 150Hz. Very old tech maybe 15 year old chip design. Great for bass Xover though.
 Probably the best alternative, to my now out of production, QSC DSP-30 is HAL's dspMusik 6x8 DSP and HiRez DAC. This thing will do everything my processor does in the way of crossover configuration and is also a Hi-Rez ADC and DAC.  While I hope my QSC DSP-30 doesn't die anytime soon, at least I have a viable alternative.
Scotty

Offline BobM

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Re: Subwoofer
« Reply #13 on: September 14, 2017, 05:07:15 AM »
I use this (NHT X-1) to crossover my speakers to my subs. It controls the subs nicely, and allows me to roll off the bottom end of my mains starting at about 100Hz.

https://www.nhthifi.com/products/11196-x1-electronic-crossover?category_id=1964922-vintage

It is really transparent, or I wouldn't be using it. The one drawback is that it goes between the pre and the amp, as it would have to to roll off the mains. But, as I said, it is really transparent.

You would have to find one used, and that's not easy, but if you are patient one may come up for sale.
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Offline doug s.

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Re: Subwoofer
« Reply #14 on: September 14, 2017, 06:34:10 AM »
hi scotty,

while your photo didn't post, the description makes your situation more understandable.  you are using the subs more or less simply to clean up the room's low bass response, as you effectively have four subs in the room.  i went thru your posts, and found your mains include two 12" woofers/side; i suspect they don't go much higher than 300hz, if that.  so, in your case, i can understand why you're not crossing over your mains.  you just need to add another pair of subs, that will fix your l-shaped room!   :thumb:

doug s.
Here is an image of the full range speakers/cat tree used in my system.

They're flat to 18Hz on their own, no equalization is used in the system other than the extra subs.
About 95dB 1watt/1 meter sensitivity.
In most residential listening rooms the Schroeder frequency below which the room starts behaving as a resonator falls between 100 and 200Hz, frequencies below about 125Hz in my room exhibit response variations, hence the relatively high Xover frequency. The subs are being operated about 20dB or more below the SPL of main loudspeakers output. Their effect isn't really noticeable until they are turned off.
  In order for effective suppression of room resonant nodes to occur via phase cancellation one must have sources of bass frequencies at both ends of the listening room. Here is a link to the short version of the paper on which my setup is based.
http://vbn.aau.dk/files/62729209/LF_sound_field_control.pdf
And a link to the long version where the problems endemic to an L shaped room are discussed at the end of the paper. http://vbn.aau.dk/files/12831869/AC-phd.pdf
 I neglected to mention that Xover has a 24/48 ADC/DAC chip and sucks above 150Hz. Very old tech maybe 15 year old chip design. Great for bass Xover though.
 Probably the best alternative, to my now out of production, QSC DSP-30 is HAL's dspMusik 6x8 DSP and HiRez DAC. This thing will do everything my processor does in the way of crossover configuration and is also a Hi-Rez ADC and DAC.  While I hope my QSC DSP-30 doesn't die anytime soon, at least I have a viable alternative.
Scotty