Adding sub to (my) "Belle's"

[CECAA850]

6 hours ago, Chris A said:

A simple distance+horn path length calculation

That makes sense in a FLH but in a Tapped horn as well?

[Chris A]

Just ignore the mouth-located portion of the woofers and consider the horn-driver configuration to be a simple front-loaded horn. 

 

Basically the position(s) of the rear side of the woofer(s) near the horn's mouth are chosen to even out the dips in response in the lowest 1.5 octave of response. Danley talks about this subject in his white paper on Synergy and tapped horns.

[CECAA850]

9 minutes ago, Chris A said:

Just ignore the mouth-located portion of the woofers and consider the horn-driver configuration to be a simple front-loaded horn. 

 

Basically the position(s) of the rear side of the woofer(s) near the horn's mouth are chosen to even out the dips in response in the lowest 1.5 octave of response. Danley talks about this subject in his white paper on Synergy and tapped horns.

Thanks.

[MookieStl]

22 hours ago, Schu said:

How the check do you time that with the mains?

Don't know! I read many favorable reviews (some not as favorable) on pairing with horn loaded woofers. I had tried direct radiating subs with my Belles and did not like the results. I built these mostly because it looked like a challenging woodworking project (had to use math too!) It seems to work for me. I stood them up in various configurations but settled on using them as stands as originally intended. Took some time to tweak, but got them dialed in (by ear) to my liking.

[Schu]

I understand... there always seems to be trade offs.

I have my direct radiating integrated as well as possible by limiting its output to lower than 60Hz... perhaps lower (tuned by ear).

[avguytx]

I know it's not going to be optimal, but, hopefully it will add the low octave for normal listening levels which, for me, isn't as loud as it once was.

[DizRotus]

Carl, @CECAA850, would agree, that multiple subs increase the SPL potential, but do NOT lower the extension.

 

In my case, the four Lil’Mike Anarchy Exodus TH subs allow me the luxury of four TH subs to permit location experimentation to smooth out bass.  Each is supposedly flat to 25hz.  After adding the second sub, it was my perception that the midrange and treble were also subjectively improved.  

 

As as you can see from the earlier posted photos, my space is limited.  The front two subs are pretty much locked into the corners as shown.  They also serve as speaker stands for  my DIY Fostex FE103 single drivers used for the HT.  Before I purchased the second iNuke 1000dsp, I powered two 8 ohm subs in parallel (4 ohm load) with each channel.  The front subs on one channel and the rears — behind or on either side of the couch — on the other channel.  The Behringer iNukes are notoriously over rated as to power, but the single amp performed well.  Only during the loudest playing of such things as DSOM, did the red lights flicker.  I expect much better performance and fine tuning capabilities using the second “tuner” (actually the second amp) just recently noticed by my wife.  With two amps, each sub can be driven, and adjusted, individually.

 

The four smaller TH subs fit my needs better than one, or more, larger sub(s).  The use of the TH subs under @MookieStl‘s La Scalas is outstanding.  So far, the TH subs have been used for TV and movies with the single drivers.  As soon as time permits, I will try them as supplements to the bass from my DIY “Super Heresy” speakers based on the work of @ClaudeJ1.  The in-room bass of the Supers is excellent for music, even without help from the Lil’Mikes.  Once the Four TH’s are used to augment the Supers, I expect them to sound even better;  one of those situations where suddenly adding or subtracting them will produce subjective changes, even though it sounds good either way.

[ClaudeJ1]

49 minutes ago, DizRotus said:

I will try them as supplements to the bass from my DIY “Super Heresy” speakers based on the work of @ClaudeJ1.  The in-room bass of the Supers is excellent for music, even without help from the Lil’Mikes.  Once the Four TH’s are used to augment the Supers, I expect them to sound even better;  one of those situations where suddenly adding or subtracting them will produce subjective changes, even though it sounds good either way.

Even though my subs are much bigger, I'm a firm believer in Todd Welti's Subwoofer research for JBL as well as the work of Dr. Earl Geddes in taming all the ROOM MODES. I have had 2, then 3, now 2, then soon to be 4 subwoofers to SMOOTH out the bass response in other areas besides the Sweet Spot. I simply cannot over stress the importance of having this method overcome the domination of room modes below 300 Hz. which is the WORST in a home environment due to small spaces. It's better to have more SMALLER subs than a single big one, like you have done. I recently failed to convince someone of this, so he'd rather have one huge one rather than 2-4 smaller ones............oh well, I tried.

 

Geddes recommends 3. One in a corner, and the other two placed assymetrically, then applying lots of EQ to fill remaining gaps. This is technically more difficult than Welti's methods.

 

According to Welti, the BEST is 4 in the MIDDLE of 4 walls. Second BEST is one in front center, and one in rear center. This is what I have currently, with my head sitting at the midpoint of the two subs. I will be adding some (new to me) THTLP "twins" to the side walls with their own amplifiers and the same MONO input as the front and rear subs. Yeah it's relatively expensive to get great bass in the high teens/low 20's with multiple subs, but the reduction in distortion allows for greater sonic enjoyment overall from more than just the sweet spot.

[jason str]

1 hour ago, DizRotus said:

Carl, @CECAA850, would agree, that multiple subs increase the SPL potential, but do NOT lower the extension.

 

This is the case with DR types and tapped horns, multiples of fully horn loaded subs not only increase SPL potential but lowers frequency extension capability and flattens out frequency response.

 

 

[ClaudeJ1]

18 hours ago, CECAA850 said:

That makes sense in a FLH but in a Tapped horn as well?

Funny thing about tapped horns. Having used both Audyssey XT/32 Room EQ and, now Yamaha YPAO (had to have those ESS Sabre DACS), they both chose the front position of the subwoofer as the timing point (not the horn length). I'll be adding a pair of Full Length Horns  (THTLP's which are about 12 1/2 feet long) to their own sub channel and I'll see how the Yamaha treats the distance delays, which are now similar to the L and R channel within ONE FOOT.

 

Fortunately, the FLH's will be on the side walls which are much closer than the front/rear walls. However, since the best and most detailed bass has come from a 40 Hz Xover point (which I think is TRUE SUB BASS and NOT this 80 Hz. crap foistered onto ignorant consumers).

[jason str]

8 minutes ago, jason str said:

 

Nothing

 

 

[Chris A]

8 minutes ago, ClaudeJ1 said:

Geddes recommends 3. One in a corner, and the other two placed assymetrically, then applying lots of EQ to fill remaining gaps. This is technically more difficult than Welti's methods.

 

Toole talks about this subject (multiple subs in a room and their locations relative to room corners/room modes) in his latest book.  Basically, he endorses Geddes' method, and mentions the "sensitivity" hit that you get when you place subs mid-wall instead of in corners.  It's a very big number (I would quote the numbers if I could find my 3rd Ed. and the notes that I made).  It's like 6-10 dB difference...

 

I recommend at least one sub in a corner, and a sub in two corners if you want to counteract the lowest room mode (which is a big deal).  The third sub would go mid-wall somewhere.  I recommend placing the subs close to the main left/right loudspeakers if you're crossing above about 60-70 Hz due to lobing and localization issues with the sub output.  I actually recommend using loudspeakers that are full range.

 

3 minutes ago, jason str said:

This is the case with DR types tapped horns, multiples of fully horn loaded subs not only increase SPL potential but lowers frequency extension capability and flattens out frequency response.

If you are saying that you don't get driver coupling with direct radiating and tapped horns that are placed within 1/4 wavelength of each other near a room boundary, then I'd have to disagree.  The room doesn't care if you're using DRs, THs, or FLHs, the effects are the same on lowering the Fc and increasing the output.  The effect of horns on "cutoff frequency" for either THs or FLHs are synonymous. You're changing the conditions of the horn mouth loading in either case, and the effect on the real part of the acoustic impedance ("R") is virtually the same on the drivers.

 

Chris

[ClaudeJ1]

2 minutes ago, jason str said:

This is the case with DR types tapped horns, multiples of fully horn loaded subs not only increase SPL potential but lowers frequency extension capability and flattens out frequency response.

 

 

This is very true.................along with wall/floor/ceiling/corner reflection loading. In my case, with the THTLP's, it will be drywall over metal studs meeting with a concrete ceiling in a loft with a 12" space, so I'm pretty sure it will extend slightly lower than the 22 Hz. Bill Fitzmaurice targeted in his design.

 

Besides, after experiencing the DIMINISHING RETURNS of Danley DTS-10 subs, that dig wonderfully deeper than anything I've ever had (and vibrate stuff at the other end of the house I had at the time), I just find VERY FEW movies (like a fraction of 1%) that have Sub Bass Spectrum Plots that go BELOW 20 Hz. I agree with Bill Fitzmaurice's decision not to design a sub horn that goes lower than the Tuba HT.........which give you PLENTY of Super CLEAN sub bass for very few watts. Heck, even IMAX theaters Specs say 23 Hz. is a low as they go, so I laugh at all the sub bas FREAKS on other forums that try to overkill stuff down to 8 Hz., the same way the thes "burp test" competitions for subs in vans want to reach SPL's louder than a 747 taking off.

 

RIDICULOUS! But, hey it's a free country.

[jason str]

10 minutes ago, Chris A said:

 

 

 

If you are saying that you don't get driver coupling with direct radiating and tapped horns that are placed within 1/4 wavelength of each other near a room boundary, then I'd have to disagree.  The room doesn't care if you're using DRs, THs, or FLHs, the effects are the same on lowering the Fc and increasing the output.  The effect of horns on "cutoff frequency" for either THs or FLHs are synonymous. You're changing the conditions of the horn mouth loading in either case, and the effect on the real part of the acoustic impedance ("R") is virtually the same on the drivers.

 

Chris

 

Feel free to disagree but you would be wrong on this fact.

[ClaudeJ1]

5 minutes ago, Chris A said:

 

Toole talks about this subject (multiple subs in a room and their locations relative to room corners/room modes) in his latest book.  Basically, he endorses Geddes' method, and mentions the "sensitivity" hit that you get when you place subs mid-wall instead of in corners.  It's a very big number (I would quote the numbers if I could find my 3rd Ed. and the notes that I made).  It's like 6-10 dB difference...

 

I recommend at least one sub in a corner, and a sub in two corners if you want to counteract the lowest room mode (which is a big deal).  The third sub would go mid-wall somewhere.  I recommend placing the subs close to the main left/right loudspeakers if you're crossing above about 60-70 Hz due to lobing and localization issues with the sub output.  I actually recommend using loudspeakers that are full range.

 

If you are saying that you don't get driver coupling with direct radiating and tapped horns that are placed within 1/4 wavelength of each other near a room boundary, then I'd have to disagree.  The room doesn't care if you're using DRs, THs, or FLHs, the effects are the same on lowering the Fc and increasing the output.  The effect of horns on "cutoff frequency" for either THs or FLHs are synonymous. You're changing the conditions of the horn mouth loading in either case, and the effect on the real part of the acoustic impedance ("R") is virtually the same on the drivers.

 

Chris

Yes indeed, you make some good points here. No disagreement, IDEALLY.

 

However, we must accommodate existing spaces the best way possible, which always seems to involve compromises. Having multiples subs reduces the nasty peak/trough ratios of sub bass, even when placed in a non ideal situations of the real world. We live with those results/consequences. All of the methods are BETTER than a single sub in a corner AND perfection is not attainable. Currently my bass is FLAT from 20-200 Hz. +/- 4 db, which is pretty darn good. I want to try and improve that. With ALL HORNS for sub bass, I can afford to "throw away" the 6-10 db you speak of. Also, REW simulation is very helpful in letting me know I'm on the right path. I'll post measurements when I'm done.

[Chris A]

1 hour ago, jason str said:

Feel free to disagree but you would be wrong on this fact.

I've not seen these facts.  It would be instructive to see them so that I don't make the mistake again of being in error on this particular subject.  Could you post the links here so that I could be enlightened?

 

1 hour ago, ClaudeJ1 said:

With ALL HORNS for sub bass, I can afford to "throw away" the 6-10 db you speak of.

Most people's setups that I've witnessed cannot give up even 1 dB of deep bass gain due to the nature of the problem, namely the narrowing equal loudness contours below 100 Hz, as seen in the following equal loudness contour plot.  Small changes in measured SPL lead to disproportionate changes in perceived bass loudness (which is particularly evident when demastering stereo music tracks for bass output in rooms that haven't been calibrated with each other carefully):

 

 

I find that all sound reproduction setups are limited by low bass reproduction SPL and nonlinear distortion (particularly amplitude modulation [AM] and harmonic distortion).  Requiring 10 dB more output from the subs results in really big changes in perceived loudness and in the cleanness of the presentation--in my experience.  Horn loading gives margin, but subtracting 10 dB of gain is like giving up 2/3s of of the gain advantage of using horn-loaded subs in the first place (amplitude) and even more in terms of nonlinear distortion.

 

Chris

[jason str]

54 minutes ago, Chris A said:

I've not seen these facts.  It would be instructive to see them so that I don't make the mistake again of being in error on this particular subject.  Could you post the links here so that I could be enlightened?

 

 

 

Just look any SPL chart using multiples of cabinets, the difference is obvious.

 

 

[Chris A]

Links please...since you stated that these were "facts".

[jason str]

Here is one graph showing multiples. 

 

 

Multiple cabinets also allows the high pass crossover frequency to be lowered a bit depending how many cabinets are used.

[Chris A]

I don't believe that figure shows what I thought you were implying above: that DR and TH subs do not experience this effect in the same way as conventional FLHs.  Perhaps I missed what you imply with this figure. 

 

In my experience, TH subs actually tend to respond more strongly to mutual coupling than conventional FLH subs due to their (typically) exaggeratedly small mouths--relatively speaking--and the relative gain in mouth loading due to having another TH sub mouth close by (within 1/4 wavelength).  A TH sub is typically looking for more effective mouth loading than conventional FLHs and therefore respond more strongly when it finds something that provides increased resistance--like a larger horn mouth, but in this case two or more coupled TH mouths.

 

A DR sub seems to gain more from mutual coupling to room boundaries and is looking for a room boundary (or another subwoofer diapragm or horn mouth) to increase loading to the DR driver diaphragm at low frequencies, thus increasing the real part of impedance to the coupled air mass. 

 

All three types (FLH, TH, DR subs) experience what the figure above shows: a lowering of the low frequency roll-off point and increased overall gain due to mutual coupling.

 

Chris