Where are the subs?


In listening to the Bach Toccata and Fugue BMV 565, I was struck by how well the organ pedal notes are reproduced since I moved my primary setup to another room. I complemented myself on a fine job of integrating the Velodyne HGS-10 subs with the KEF Ref 1s, using 40 Hz low-pass with 24 dB/octave. But as I thought about it, I didn’t recall connecting the SMS-1 bass manager to the Ayre KX-5 Twenty preamp. I checked. The subs were not connected. The Ref 1s alone where reproducing that satisfying bass. Amazing for stand mounted monitors. I sure as hell didn’t expect that. To confirm, I played the Saint-Seans 3rd Symphony. Same result. Makes me wonder if I need bother connecting the subs.
Ag insider logo xs@2xdbphd
Hi dbphd,

     I hope the recipient of your gift was appreciative of your largesse, quite an impressive gift!
     The DBA concept is designed with either a hard surfaced or a carpeted floor and untreated walls and ceilings in mind.  The free reflections of bass sound waves off room boundaries increase the number of bass modes (bass peaks and dips) in the room and, therefore, are considered beneficial.  I'm not sure if and to what degree a carpeted wall and partial ceiling will effect the performance of a 4-sub DBA system.    My room has full carpeting on the floor but no other room treatments at all.
     I wasn't familiar with the velodyne SMS-1 bass manager so I read this older review:
https://hometheaterhifi.com/volume_12_4/velodyne-sms1-digital-drive-sub-manager-12-2005-part-1.html

     It's an interesting product.  My overall impression is that the SMS-1 and the DBA system have the same goal, to achieve accurate natural and smooth in-room bass response, but through different methods.  It strikes me that the SMS-1 method is trying to simulate digitally what our brains do naturally with the DBA method.  

     The SMS-1 approach is attempting to smooth or even out bass peaks and dips in a room through room analysis using test tones and mics, digital conversion and processing along with parametric equalization.  It's more proficient at reducing bass peaks than boosting bass dips since boosting all bass dips of various frequencies and decibels needs to be done more judiciously to prevent overstressing the sub or subs.
     The DBA approach is attempting to smooth out bass peaks and dips in a room through creating more peaks and dips and relying upon the proven psycho acoustic principle of our brains summing and averaging these peaks and dips which results in a perceived accurate and smooth in-room bass response.  It's equally proficient at reducing bass peaks and boosting bass dips since boosting all bass dips of various frequencies and decibels requires no increased bass output from the sub or subs.
      I'm certain the 4-sub DBA system works like a charm without any mics, room analysis, room correction software or hardware, parametric equalization and room treatments.
     I've never used or heard a 4-sub DBA system configured through an SMS-1 and utilizing room correction so I'm not certain how well this method would work.
    Since I know for certain the 4-sub DBA works extremely well without room correction of any type, however, my opinion is there's no need to complicate the 4-sub DBA configuration and setup by using it.
     If you have the time and inclination, you could try it both ways and determine which setup you prefer.....in the name of science, of course.
     I know from personal experience that using two 15" inch subs is capable of providing very good bass response at a single designated listening position, even without using DSP room analysis and room correction through parametric equalization.
     I don't know whether two 10" subs utilizing the SMS-1's room correction is capable of providing very good bass response at your listening position.  But my concern is that these subs may be overdriven and overstressed if the SMS-1 detects numerous large bass dips(more than -3db down at a frequency) at your listening position.
     Have you made a decision on whether you're going to get your 15" Velodynes repaired or just invest in the AK Swarm? 
    I'd suggest hooking up your turntable and phono stage but waiting until you have 4 subs before bothering with the SMS-1.  I really believe, if you properly position and configure all 4 of your Velodynes in a custom DBA or use the 4-sub Swarm DBA, you'll agree there's no benefit in using your SMS-1.

Tim
Tim, I will have my HGS-15s repaired, but it takes planning. I’m 83, so I need help to put them in the back of the station wagon, then they need to be hauled to LA within a day or so, a two-hour drive from Santa Barbara. I have several SMS-1s, so I plan to us both the HGS-15s and 10s. Running the automated SMS-1 acoustic room correction is easy, but you can spend hours manually tweaking acoustic parameters if you wish.

I’m skeptical of your last sentence. The Ayre preamp connects to the SMS-1 which connects to the subs. I never use subs without acoustic room correction.
@dbphd, the DBA concept and what you can accomplish with your SMS-1 are pretty much one and the same. Use what you're comfortable with or try both and see what you prefer. I have used the DBA concept with 4 subs for a few years now. No room correction was ever part of the equation, didn't feel the need for it. I am trying out a line array concept now that member mijostyn recommended and find this method useful too. IIRC, he uses DSP in his setup, but again I do not. Ultimately I think the use of 4 subs will make a nice difference in your system.

BTW - was at the show in Long Beach yesterday and ran into Doug. Had a nice time. I'll be heading to LA in the next coupe months so I'll try to make a point of stopping by.
I'd enjoy a visit from you.  I have two setups: (1) Ayre 5 Twenty series digital hub, preamp, and amp with KEF Ref 1s, and (2) Senore microRendu, Ayre Codex, and Ayre A7e amp with LS50s.  Lots of Parasound stuff boxed to sell; beginning to wonder about setup 1.  I think we're a year or two down the waiting list for Casa Dorinda.  Perhaps a pair of KEF LS50s arrayed with a pair of Velodyne HGS-15 and a pair of HGS-10s would satisfy my audio needs.
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