[smithy666]

I'm thinking of adding small sub to my 1801s (current thoughts are a SS 23W/4557T in a 1 cu ft sealed box), as I would like to get a bit more lower bass response. I'm thinking of using an electronic 24db slope crossover, crossing around 80Hz. Crossover and amp wouldn't be in the sub box, but back with my main preamp/amps. Thinking of using the Borbely 1102/215 crossover for quality/simplicity.

Has anyone played around with adding a sub, particularly crossover frequencies & slope? Interested in any thoughts/suggestions. 

[David Ellis]

I can offer some help, but not significantly.

I have subjectively decided that adding a subwoofer has more disadvantages than advantages.  I do think your 80hz guess is very reasonable, but you will have to place the sub in the center to obtain a decent soundstage. 

I believe the the historic "jury" on the 1801 and subwoofers is divided about 70/30% for those who have tried subwoofers.  I don't track this feedback in exhaustive detail, but my guess is that 70%of folks with subwoofers decided the integration was more painful than enjoyable.  I was certainly IN this group.  However, my subwoofer couldn't be placed in the center.  I believe this would have helped at least 1 problem.

However, very few folks have used high quality product like the Borbely unit.  I believe that IF the subwoofer is centered and IF the subwoofer is well built well the implementation has a very good chance of success.

I must also admit the SS driver you mention is a high quality unit. The sensitivity is a bit low, but this makes the smaller cabinet viable.

Dave

[Brucemck]

David, why the emphasis on "centered"?

I use two subs, one each on the inside of my left and right mains, (pretty close to mirrored around the rooms center line) with a third very small sub at the back of the room at a much lower volume that evens out the response.  All three are run as a mono signal.

[David Ellis]

David, why the emphasis on "centered"?

Most folks run a single subwoofer.  IME and most folks seem to agree that it will eschew the soundstage if placed off center.  Dual subwoofers symmetrically on the left/right will accomplish the same thing.

Yes, I know my comments about the directional audibility of subwoofers is opposite many home theater opinions.  But, I can hear the soundstage eschew, and others have too.  Using a single off center subwoofer for a home theater system might be fine.  Expecting perfection when integrating a single off center subwoofer in a hifi application is extremely difficult/impossible IMO.

Dave

[smithy666]

Dave
Thanks for your views. I plan on placing the sub bang in the middle of the 1801s - this works beautifully (by chance) in the room they are in, so hopefully I can address the soundstage problem. On the crossover frequency the more I have looked at it the more I think I will cross over at 100Hz using 24dB LR active. Erno Borbely has been extremely helpful with the crossover, so I am feeling good about this side of the project. His design seems very good - all low noise jfet, extremely well engineered, so I don't expect it to have any negative effect on the 1801s.
The sensitivity is low, so I am looking at using one of Borbely's 300W into 4 ohm amp designs as well to drive. From the calcs I have done a 37 litre sealed box will be about right with f3 around 30Hz.
It will take a little while to get all this going, but I'll report back when I've progressed a bit.

[BrianM]

Dave
Thanks for your views. I plan on placing the sub bang in the middle of the 1801s - this works beautifully (by chance) in the room they are in, so hopefully I can address the soundstage problem. On the crossover frequency the more I have looked at it the more I think I will cross over at 100Hz using 24dB LR active. Erno Borbely has been extremely helpful with the crossover, so I am feeling good about this side of the project. His design seems very good - all low noise jfet, extremely well engineered, so I don't expect it to have any negative effect on the 1801s.
The sensitivity is low, so I am looking at using one of Borbely's 300W into 4 ohm amp designs as well to drive. From the calcs I have done a 37 litre sealed box will be about right with f3 around 30Hz.
It will take a little while to get all this going, but I'll report back when I've progressed a bit.

I'd be interested to hear about the results, as my own room would allow for a center-placed sub, too. Also the price of the subwoofer you'll be trying...

[duggie]

the only way to successfully integrate a single sub is to place it in the exact center, imo.  nearfield is better, if possible.  that way, it will only marginally impact soundstaging.  stereo subs are the way to go, w/the subs either just inside or just outside the main speakers.  instead of marginal degradation of soundstaging, you will actually get an improvement.  and, two subs are much easier to integrate into a room - having more than one bass source evens out the room loading.

and, unless your main speakers have a bad bass hump somewhere above 80hz, i would strongly recommend an x-over frequency between 40-80hz, depending on your main speaker's bass extension. especially if you insist on using a single mono sub.

[BrianM]

the only way to successfully integrate a single sub is to place it in the exact center, imo.  nearfield is better, if possible.  that way, it will only marginally impact soundstaging.  stereo subs are the way to go, w/the subs either just inside or just outside the main speakers.  instead of marginal degradation of soundstaging, you will actually get an improvement.  and, two subs are much easier to integrate into a room - having more than one bass source evens out the room loading.

and, unless your main speakers have a bad bass hump somewhere above 80hz, i would strongly recommend an x-over frequency between 40-80hz, depending on your main speaker's bass extension. especially if you insist on using a single mono sub.

Probably a dumb question, but is the goal here (monitors + stereo subs) supposed to be an outcome that is *better* than you would have with good 3-way speakers? Or just less expensive? When it comes to having 2 subwoofers for the 1801s aren't you now in the price range of just getting really good 3-ways? Whole greater than sum of the parts, or what?

[gooberdude]

I've been playing with a mono sub lately and have had great success, or rather pleasure, with the outcome.

For me and my room, placing the sub so it interacted properly with the room was WAY MORE crucial than where the sub sits in relation to my floorstanding 3 way towers.  Of course, indidual mileage is gonna vary with subs.  the sound was OK with the sub right in the middle of my speakers (and within +,- 1" the distance from my ears as the woofs in my main speaks) the damn thing started singing when i placed it within a foot of a corner.   With the sub in the middle of my room, it sounded like a woofer.  With it in a corner, it sounded like a sub.    My sub is kinda small for my room though, so i might have needed the corner db boost.

Moreoever, i'm finding that the way it connects to the floor (and the room) is just as crucial as the room placement location, maybe even moreso.   My single Hsu sub sits on top of 3 mapleshade 2" flat top footers and the whole contraption sits on a 4" thick hunk of air dried mapleshade maple that's 12" x 15" and has the MS floor spikes...its the smallest Hsu sub, STF-1.  Living in a condo with poured concrete subfloors relegated me to finding a proper mounting.

i have no doubt that stereo subs will sound good, but the way mine is connected with the room helps it integrate tremendously...and (i think) i have really sensitive hearing for this stuff.  If the soundstage was somewho skewed to one side or another it would be audible - and its not.

Since the mounting i've chosen makes a $250 sub cost about $600, i'm stuck with mono sub-bass for a while.  However, i'd be miserable if I spent the $ on 2 identical subs and had to set them both on the carpet.  Tough to get fast, tactile, musical sub bass with crappy footers set into carpet...

incorporating a sub in the room requires a lot of trial and error, but its fun and enlightening.  you just have no clue what info is on recordings below 50hz...

[duggie]

the only way to successfully integrate a single sub is to place it in the exact center, imo.  nearfield is better, if possible.  that way, it will only marginally impact soundstaging.  stereo subs are the way to go, w/the subs either just inside or just outside the main speakers.  instead of marginal degradation of soundstaging, you will actually get an improvement.  and, two subs are much easier to integrate into a room - having more than one bass source evens out the room loading.

and, unless your main speakers have a bad bass hump somewhere above 80hz, i would strongly recommend an x-over frequency between 40-80hz, depending on your main speaker's bass extension. especially if you insist on using a single mono sub.

Probably a dumb question, but is the goal here (monitors + stereo subs) supposed to be an outcome that is *better* than you would have with good 3-way speakers? Or just less expensive? When it comes to having 2 subwoofers for the 1801s aren't you now in the price range of just getting really good 3-ways? Whole greater than sum of the parts, or what?

imo - subs will improve most any speaker system, regardless of whether they are two way, three way, etc.  assuming, of course, that you have high-quality subs, & that your speakers do not already have subs as part of the package.  something like the old infinity irs-v's come to mind, or their later genesis brethren.

when i 1st got my subwoofer system, i had 3-way speakers that went from 20hz to 19khz, +/- 1.5db.  not only did the bass response improve, but the upper bass/lower midrange improved as well, as my main speakers no longer saw anything below 70hz, meaning their 10" woofers no longer had to stress the low notes, enabling them to play their upper range more accurately.

[gooberdude]

i totally agree with Duggie.   

My Thiel CS2's play fairly low, but not nearly as low or with the taut authority that the Hsu sub provides...

[duggie]

i totally agree with Duggie.   

My Thiel CS2's play fairly low, but not nearly as low or with the taut authority that the Hsu sub provides...

funny you should mention thiel cs2's as your speakers.  when i got my pair of vmps larger subs, w/marchand outboard x-over, my main speakers were thiel 3.5's...   

now, go get that second sub, especially if you have sized the single one too small for your room.  locate them for proper stereo, & you will like what happens.   aa

[gooberdude]

If I get a fat check back from the Govt after tax time i'll defintely think about it... I have the space for a 2nd, just not the extra $ for the footers and maple stand.

i'm just waiting for that 1 session when i realize something is terribly wrong and only a 2nd sub can cure it!    No doubt that adding the 2nd sub would pressurize the room better.  Subconsciously i chose the smaller STF-1 just so i could add its stereo partner in the future.   

The Thiel 3.5's are much better speaks than my vintage i think...these were the 1st speaks i bought.   I've tried several newer pairs of other speaks to replace them, but can't get past the fullrange sound.  now with the sub, its even more difficult.

Having a full range speaker + a musical sub is like a vacation that lasts 24/7.

i have a pair of really nice monitors, Merlin clones.   But when i increase the range of the hsu x-over, say to 80hz, that combo doesn't grab me like the  Thiels + Hsu combo does with the sub x-over at 37hz.   


matt

[duggie]

If I get a fat check back from the Govt after tax time i'll defintely think about it... I have the space for a 2nd, just not the extra $ for the footers and maple stand.

i'm just waiting for that 1 session when i realize something is terribly wrong and only a 2nd sub can cure it!    No doubt that adding the 2nd sub would pressurize the room better.  Subconsciously i chose the smaller STF-1 just so i could add its stereo partner in the future.   

The Thiel 3.5's are much better speaks than my vintage i think...these were the 1st speaks i bought.   I've tried several newer pairs of other speaks to replace them, but can't get past the fullrange sound.  now with the sub, its even more difficult.

Having a full range speaker + a musical sub is like a vacation that lasts 24/7.

i have a pair of really nice monitors, Merlin clones.   But when i increase the range of the hsu x-over, say to 80hz, that combo doesn't grab me like the  Thiels + Hsu combo does with the sub x-over at 37hz.   


matt

if you like the thiel sound, keep your eyes peeled for a pair of used 3.6's.  better than the 3.5's in every way, except they only go down to 28hz instead of 20hz.  but, if you have subs...   

since i have stopped using the 3.5's, i have had mostly monitors w/my subs.  meret re's, proac tablette 8 ref sigs, diapason adamantes lll's, & a pair of floorstanders that go down only to 36hz - the coincident victory's.  all these kicked the thiel 3.5's booty, imo...  and, the positively tiny proacs, as well as the meret's, were used in a huge room - ~26x38x8.5, w/openings to two other rooms as big as the room the speakers were in...

never heard your merlins, but i suspect they need a second sub, & x-over lowered to ~50-60hz, to show their full glory.

[DSK]

A single sub does not necessarily need to be located exactly centred between the main speakers. This is only required when the frequency and slope of the sub's low pass filter are too high and too shallow respectively. The sub then becomes locatable by ear. This is supported by the fact that many people take advantage of room acoustics by locating their sub(s) in corners, with no negative effects.

There are many systems in which the addition of a subwoofer seems to detract from the reality of the performance. IMHO this is almost always due to two things ... the sub is not good enough and/or the sub's integration has not been optimised. The sub must be of high quality, well damped, mounted in a suitably large and rigid box, and be driven by an amplifier with plenty of headroom. The sub must have a Q of between 0.5 and 0.7 (not the typical 0.7+ used in many home theatre subs). For music it does not need to go down to 0Hz but will ideally be flat down to 30Hz. IME sealed subs are preferable for music, regardless of whether the mains speakers are sealed or ported.

Optimising the integration of the sub includes: location; feet/platform; LPF frequency; LPF slope; phase; gain; and optionally HPF frequency and slope on the main speakers. The optimal settings for all of these will largely depend on your main speakers and your room acoustics and will be different from system to system and room to room. This is why so few people ever get to hear their subs truly optimised. It is very time consuming, confusing and even frustrating to do by ear alone. I use the Acoustisoft ETF5 measurement software and find it saves me a great deal of time and gets me to optimisation levels I probably couldn't attain by ear alone. Unfortunately, most sub owners seem to have the sub's gain and/or LPF frequency set a little too high and this causes muddied lower mids and a bloated bass, with a discontinuity between sub and mains speakers. An excellent sub, optimally integrated with excellent main speakers (either stand mounted or floor standers) adds a dimensionality, scale, effortlessness and openness that can't be matched by even $$$$ 3-way floorstanders on their own (except perhaps very high end speakers with high quality 10"+ woofers and tri-amping). The music just comes alive! Often the mids will also be improved with better body and tonality and the overall balance is more natural and lifelike.

My single sub (DirectServo, 12" driver, rigid & sealed 2 cu.ft. box, 24db/oct LPF, switchable Q 0.5/0.7/0.9) is located just inside my right speaker. My speakers are very high quality standmounts (6.5" SS Revelator, rigid & sealed 0.75 cu.ft. box). I let the main speakers run full range and have the sub's LPF set to 63Hz. In my large-ish room this provides a +/-5db response from 16Hz on up. This has provided a seamless integration and, if you were to walk in blindfolded, you would swear you were listening to very large floorstanders rather than a sub with standmounts. This setup offers the excellent imaging that high quality standmounts are known for, along with the great bass that only the best floorstanders are capable of.

I am no bass-head, but one thing I have found is that once you have finished optimising the sub/mains integration and it measures flat, then turn up the sub's gain just a little (half of one o'clock position or 15 degrees in my case). Our ear/brain seems to find this more realistic and lifelike than a perfectly flat response.

Sorry for raving on, I hope this is useful to someone.

[smithy666]

Thanks for sharing your experiences. I was looking at a 37L sealed box with the ScanSpeak sub, for a Q of 0.707. I had some feedback from others who have used this sub in a larger sealed box (50-60L) that they would go for a smaller box next time.  Isn't one of the problems of a lower Q being the greater cone excursion, particularly in the 10-20Hz region, which in the case of this driver would exceed the maximum driver excursion for any decent amount of power input, thus requiring a subsonic filter?
I will play around with the xover freq to try to optimise the 1801/sub match, but maybe 80Hz would be a better starting point.

[DSK]

Smithy, it will depend on what driver and what sub amp you use (whether it has subsonic filters etc etc to avoid damage).

The xo freq for your sub will depend upon the measured rolloff of YOUR 1801's in YOUR room, and whether you will be using HPF's on the 1801's or leaving them to run full range. Sometimes, the optimal LPF freq for the sub is not the same as the -3db or -6db rolloff point of the main speakers (or the HPF freq if using HPF's), it depends upon your room acoustics.

[gooberdude]

Hey DSK,

thanks so much for the great info.   

I have an issue for you (or anyone)...

My Hsu sub is connected to the TVC preamp via a single interconnect, so the sub receives a full range signal.   I can't hear high frequency info coming out of the sub per se, when its the only thing turned on, but i can hear tones and music well above the 37Hz cut-off point i've chosen on the x-over...to the point where i could name the song since its beat is audible - if i were standing right next to the port.  Its a Hsu STF-1, pretty basic sub.

I think the sub is integrated mighty well, often i forget its there... BUT, if i concentrate real hard it would not be an issue to blindly pick out its location in the room.  No idea if my ears are real sensitive, but it sounds like heavy bass coming from the corner and not anywhere else (again, only if i'm focused on that though).

Would connecting the sub via speaker cables rather than a single interconnect affect this at all?     I'm happy as hell with the sub the way it is, but i'm new to bass augmentation in the home...so i have beginner issues!

I keep the volume only about 30% of the way up, around 10 - 11 o'clock...not loud.

it just seems like there are sounds well above 37 HZ coming out of it...even when i dial the x-over knob all the way down to 30hz.

my floorstanding Thiel's run full range...


matt

[DSK]

Matt, what is the rolloff slope of the sub's low pass filter? And, have you set up the sub by ear only or by measurements?

[gooberdude]

I've only played with it by ear...but so far the results are too my liking...at least compared to when i 1st began playing with it.

The x-over slope is 24db according to the mfgr site
http://www.hsuresearch.com/products/stf-1.html


Even when i turn the x-over's low pass knob all the way down to 30hz, the issue i reported earlier is still audible.   It doesn't bother me really, just an observation.