Lack of bass extension with SDA 2B's

bjaudio

Hello,
I recently acquired a pair of SDA 2B's in great shape. The sound is wonderful with the exception of limited low bass extension. Could this be a cross-over issue?

I am pushing them with a Denon 3803 receiver set in Pure Direct (analog bypass mode) as a pre-amp. The Denon then sends the signal to a 30-year old Marantz 140 amp (75 watts RMS @ 8 ohms).

I tried running the speakers directly from the Denon as well.....same result.

The speakers are positioned about 6 inches from the back wall.

Thanks for your assistance!

ben62670

Welcome to Club Polk.
Your speakers would benefit from more power. I am not familiar with your amp. Hopefully someone will chime in. A simple test that you can do is to push in on the passive radiator, and hold it there. Tell us how long it takes for the mid woofers to return to their resting state.
Ben

ND13

how big is your room?

Conradicles

I just got some of these speakers as well. My low bass is outstanding. The Polk Audio manual says to move them closer to the wall for more bass. Mine are 12" from the wall, but I also have a huge VMPS sub to give me the bass I need. (and my neighbors as well):)

Try to move them closer to the wall...but better than that, go into you EQ on your receiver and turn up the bass at the lowest level. This may help a bunch. Give them a chance, they are great speakers but are highly sensitive to room placement and room acoustics.

billbillw

bjaudio wrote: »

Hello,
I recently acquired a pair of SDA 2B's in great shape. The sound is wonderful with the exception of limited low bass extension. Could this be a cross-over issue?

I am pushing them with a Denon 3803 receiver set in Pure Direct (analog bypass mode) as a pre-amp. The Denon then sends the signal to a 30-year old Marantz 140 amp (75 watts RMS @ 8 ohms).

I tried running the speakers directly from the Denon as well.....same result.

The speakers are positioned about 6 inches from the back wall.

Thanks for your assistance!

Make sure the speakers are not wired out of phase. This is not an insult. I had a problem where the colored nuts on the binding posts had been reversed. I had them wired according to color, which is logical, but it ended up being wrong. The result was weak low bass. This happens because the old style Polk binding posts allow the nuts to be completely removed.

When I checked the wiring diagrams and looked closer, I noticed that they were reversed on one side. A quick swap fixed things and dramatically improved the bass. I think the label should indicate the correct external wiring

MillerLiteScott

Also take a philips screw driver and tighten?snug all of the screws on the drivers and terminal cup. Every pair of vintage polks I have picked up the screws were slightly loose and possibly allowing air to escape which is a passive radiators worst enemy.

Scott

bjaudio

Thanks for all of the feedback. Many great ideas.
My listening room is a basement family room. Carpeted, lots of soft furniture, about 14' x 22', drywall walls and ceiling (7.5 feet high).

The other element that I neglected to mention is that I commonly listen to music at -15 to -25 db depending on a vinyl or cd source. I realize that this might be relatively low volume but all of the other frequencies are clear and present.

Thanks again!

HB27

You might lightly push in on the mid woofers and make sure you don't have midwoofs locked up. Make sure all four of the mids are working.
Good luck

F1nut

Check the drivers as others have indicated. If there's no problems there, you need an amp capable of producing high current.

Audio NUT

if your listening at low volume, the bass is usually first to suffer performance, Try getting an active crossover if your amps are powered from a pre amp and turn the bass controls till you hear bass, If your not bi-amping get a EQ and again turn the lows up and mids and highs down. My advise is PLAY them louder. bass needs air and movement, at low volume its like a river with no water.. Youll always be thirsty

F1nut

Try getting an active crossover if your amps are powered from a pre amp and turn the bass controls till you hear bass, If your not bi-amping get a EQ and again turn the lows up and mids and highs down. My advise is PLAY them louder. bass needs air and movement, at low volume its like a river with no water.. Youll always be thirsty

I take it you've never owned or understand how SDA's function because that's a whole lot of really bad advice.

danger boy

i've also found the SDA's to be dependent on the music you listen to and how it was recorded. I like a lot of 80's pop music.. and for some reason I keep running into a lot of that music with very little bass in the recording/CD.

I find that my SDA 2B's do bring pretty good bass, but only when it's on the source music, otherwise I don't hear a bunch of bass either. I'd be freaked out if everything I listened to on the SDA's were bassy.

I'm also running a high current amp at 120wpc, and I am hearing bass in music I have never heard before.. but here again, only when the music was recorded that way.

Try playing many types of different music. Music that you know has a lot of bass in it.. and if your 2B's are not reproducing it, then there is a chance your amp doesn't have enough high current power or there could be something wrong with your speakers.

YMMV;)

ben62670

F1nut wrote: »

I take it you've never owned or understand how SDA's function because that's a whole lot of really bad advice.

+1000

Sorry Audio Nut, but if you are not getting good bass out SDA's there is some sort of problem. The advice you gave would be good for car audio, but not HiFi, or even mid fi. If SDA's don't have good bass it is an air leak somewhere, loose wire, frozen mid driver, wired out of phase, weak amplification, or you are trying to fill too big a room with too small an SDA.
Ben

Stew

I've owned SDA 2B's for almost 20 years and have moved them from small apartments to various size basements over the years. The bass has always been good – once I finally got them set up right for the particular room.

I recently moved them into a room that is similar to the size of your room with a very large opening that leads into another large room. When I first hooked them up, there was no bass. It was like listening to small monitors. I seriously considered larger SDA's, subwoofers, etc. but decided to play around some more with room placement first. I discovered several things and found good bass again. If all the other suggestions check out (high current amp, good drivers, no air leaks, close to wall, etc), try playing with speaker and listener location.

In every other room I've tried, the bass became overpowering and boomy if I moved them closer than 5-6” from the wall. In this room, 3-4” produces solid bass and they're still not boomy. I've always known that moving them closer/further apart affects the imaging/sweet spot but in this room, it also affects the mid bass punch. I ended up placing them a little over 8' apart on the long wall. At this point, I discovered that my couch was sitting in a dead spot for bass against the opposite wall. Moving the couch a few feet into the room not only put me in the sweet spot, it improved the bass considerably. The bass hits me in the chest now even at low volumes.

There are two placement absolutes: 1) No toe in; and 2) the listening position should be equal to or greater than the distance between the inside edges of the speakers. The sweet spot tends to be where the listening position is just slightly greater than that distance. I have had better luck setting them up on the long wall although either wall can work. Good luck and let us know what kind of success you have.

MillerLiteScott

Great Advice Stew.

dudeinaroom

If this is your first adventure in to better speakers, you may be suffering from non-bloated bass. A lot of cheaper speaker either have no bass, boomy bass, or one note bass. The SDA's do bass very well in my opinion. Try checking the above mentioned. Running off of my denon the bass is a little thin (even when I had my Adcom hooked up to the denon running in pure direct, the Adcom did help though) goo luck, and let us know your findings

Later,
dude

bjaudio

Thanks again for everyone's input. Phase is fine, no leaking air, the midwoofs move fine. As suggested, I moved things around in my listening room and that made a discernible difference. I also swapped out my Denon for an old Sansui 2000A as the preamp and that improved things further. I am now a happy camper.

Thanks again to the community!

ben62670

Glad you are happy:)
Enjoy those SDA's.
Ben

sda2mike

your marantz might be needing some new caps by now...