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Placing speakers on top of subwoofers

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stunta

stunta

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No F8 or FM8, however, and I think they are going to be dropping those IIRC

I'll check with them on this. If true, I suppose I'd better get on with ordering them soon.
 

Sal1950

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Quick OT question, trying to help a long distance friend with a base sub setup.
He has Revel F208s and will be mating to a Rhythmic E15. He has a Parasound Halo P5 that has built in crossover with adjustable low and high pass filters. Where do you think a good starting point would be for the X-over freq?
Revel Low Frequency Extension -10dB@23Hz, -6dB@27 Hz, -3dB@31Hz
TIA
 

DonH56

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Quick OT question, trying to help a long distance friend with a base sub setup.
He has Revel F208s and will be mating to a Rhythmic E15. He has a Parasound Halo P5 that has built in crossover with adjustable low and high pass filters. Where do you think a good starting point would be for the X-over freq?
Revel Low Frequency Extension -10dB@23Hz, -6dB@27 Hz, -3dB@31Hz
TIA


The Dolby/THX default is 80 Hz as that's where most folk cannot localize the bass. Given that crossovers are not brick-wall filters that instantaneously cut off I prefer to set the crossover an octave away from the speaker's -3 dB point. That would be 62 Hz. Floyd and Kevin at Revel both state to use 80 Hz as well so I would start there and go no lower than 60 Hz. Depending upon the room and placement a little higher or lower may provide better response.

FWIWFM - Don
 

andreasmaaan

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FWIWFM I have a number of Rythmik subs in the house. I like 'em and Brian (Ding) and I have similar day jobs so I am biased. No F8 or FM8, however, and I think they are going to be dropping those IIRC (haven't spoken to Brian in a while). The FM8 is designed as a midbass driver with higher crossover and broader feedback bandwidth (all Rythmik subs are servo controlled, one reason I gravitated to them, since my first sub was a DIY servo based on similar principles ages ago).

Your original idea @stunta of a crossover point closer to 250Hz is looking increasingly attractive :)
 

Sal1950

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The Dolby/THX default is 80 Hz as that's where most folk cannot localize the bass. Given that crossovers are not brick-wall filters that instantaneously cut off I prefer to set the crossover an octave away from the speaker's -3 dB point. That would be 62 Hz. Floyd and Kevin at Revel both state to use 80 Hz as well so I would start there and go no lower than 60 Hz. Depending upon the room and placement a little higher or lower may provide better response.

FWIWFM - Don
Thanks Don!
 
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stunta

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Two FM8s should be arriving this Friday. Usually when I dial in a subwoofer, I adjust the volume by ear. Now with the FM8s, I will likely use them for 50Hz-250Hz and fill in the bottom end with my REL. Is there a more reliable way to get the volumes on everything dialed in than just using my ears?

I just realized one advantage of a single-cabinet large loudspeaker is that one doesn't have to worry about level matching.
 
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stunta

stunta

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A microphone.
Keith

Sure but I wanted to know if there is a well-established process. Given the room's response is not flat, how do I calibrate if I am playing a frequency sweep tone?
 

Purité Audio

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Sorry yes REW software is where you would start, measure your speakers in their current positions, fix any issues and go from there.
Keith
 

andreasmaaan

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Sure but I wanted to know if there is a well-established process. Given the room's response is not flat, how do I calibrate if I am playing a frequency sweep tone?

There are a number of ways to do this, but let me suggest one thorough and reliable method:
  1. Firstly, read up on how to measure speakers if you haven't done it before (this article is not a bad start, and this article is about REW specifically).
  2. Set the levels so that the speakers are at a moderate/typical level at the listening position (or take a gated far-field measurement so that the speakers are at an arbitrary/standard level of say 84dB or 90dB at 1 metre).
  3. Next, take a ground-plane measurement of your ATCs at the reference level with no filters in place. Note down the distance from mic to speaker, and also note the SPL across the region in which the crossover will likely be (around 150-250 Hz, where the speakers should measure fairly flat).
  4. Use your preamp to set a high-pass filter (HPF) around where you want to cross over to the subs, say 200Hz to begin with.
  5. Take another ground-plane measurement of the ATCs to ensure they are crossing over at the intended point and with the intended slope. For example, if the preamp uses 4th order Linkwitz-Riley filters, setting a 200Hz HPF should mean that the speakers are -6dB at 200Hz (relative to the level at 300Hz+), and about -24d at 100Hz.
  6. Take the FM8s outside for a ground-plane measurement (without any filters dialled in) at the same fixed distance and adjust the level until it hits your chosen reference level around the middle of its intended operating range (say 100Hz).
  7. Set a low-pass filter (LPF) at 200Hz for the FM8s, using the same slope as you did for the ATCs (e.g. LR4).
  8. Take another ground-plane measurement to ensure that they are also -6dB at the crossover point relative to the reference level and -24dB at 400Hz.
  9. Now stack the ATC and the FM8 as you ultimately will when they're set up, and take another ground plane measurement, but with both the speaker and woofer on their sides (so that both are touching the ground). If you're lucky, the crossover will work correctly and you'll end up with a flat response through the whole bass and low midrange. You've now correctly crossed over the ATCs to the FM8s.
  10. If you're not so lucky, there will be a dip or perhaps peaks at some point around the crossover. If that's the case, post the measurements here and we'll go from there :)
If all that is too much work, there are much simpler albeit less reliable ways to do it in-room.
 

Purité Audio

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The reason I am such a big fan of completely full range loudspeakers!
Keith
 

Soniclife

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Two FM8s should be arriving this Friday. Usually when I dial in a subwoofer, I adjust the volume by ear. Now with the FM8s, I will likely use them for 50Hz-250Hz and fill in the bottom end with my REL. Is there a more reliable way to get the volumes on everything dialed in than just using my ears?.

I would find a way to ensure you have confidence in the crossover slopes being what you expect, and then play with the levels by ear for a while, nothing wrong with playing with it by ear for a bit. Make notes.

Don't assume your Rel is better at the bottom end than your new ones, it might be better used to help over the very low frequencies, and do the distributed bass thing.

I just realized one advantage of a single-cabinet large loudspeaker is that one doesn't have to worry about level matching.
And one of the disadvantages of most if that they cannot be dialed in other than by moving them about, you have way more control.

Have you read this thread...
https://www.audiosciencereview.com/...m2-audiolense-digital-crossovers-w-subs.2369/
 

Sal1950

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The reason I am such a big fan of completely full range loudspeakers!
Keith
They have their limitations when compared to using multiple subs-locations.
 

Purité Audio

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No. You can still use other subs destructively, to have full range loudspeakers like the 8Cs already puts you ahead of the game .
Keith
 

Sal1950

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No. You can still use other subs destructively, to have full range loudspeakers like the 8Cs already puts you ahead of the game .
Keith
We were discussing sub-woofers remember.
See the title of the thread.
I wouldn't call 8C's a deep bass speaker in any case.
 

Purité Audio

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They have to go below the threshold of audability for you to call them a ‘deep bass’ speaker don’t be silly.
Keith
 

Sal1950

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They have to go below the threshold of audability for you to call them a ‘deep bass’ speaker don’t be silly.
Keith
Yea OK, your right. NOT
Quit whoring your products and sales in every thread, that's what DESPERATE DEALER is for.
(edit) typo corrected so Keith can find his way home)
 
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DonH56

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The problem is usually that the best place for the mains is rarely the best place for the subs due to things like room modes and SBIR. and most full-range speakers distort badly when presented with large deep bass signals. I prefer to let subs do the job. Plus I get an extra octave-plus of bass beyond even what my Salon2's are rated.
 
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