[J Harris]

OK, first post:

I recently acquired a pair of 626Rs with spiral tweeters and soundcoat. I've been using them for about a week.

My problem is boomy bass and mid-bass, not something I've seen anyone else here comment on. They sound lovely on acoustic folk music or anything that doesn't have much under 160 Hz. But anything full-range suffers from distinctly thuddy bass. Plus congestion in the mids, not something associated with the ribbon mids!

I originally had them on somewhat flimsy Atacama stands, and have now moved them on top of my ACI Titan subwoofers, pushed so that the baffles are right at the front of the subs. The subs are massive, spiked to the floor and NOT TURNED ON at the moment. I'm simply using them for stands. The are positioned about 5 feet out from the back wall, and 2 1/2 feet from the side walls, firing forward. (I've tried toe-in but it only exacerbates the problem.) The room is 12' wide by 25' long, with two side openings on the right wall, and the speakers are at the short end.

Any suggestions? Perhaps they just need to burn in further? Right now they have maybe 100 hours on them including factory burn-in.

Oh yeah, upstream electronics:

Acoustic Solid One turntable/Ortofon RS-212/Ortofon GM Classic
Bottlehead Seduction phono stage
Rogue 99 Magnum preamp
Pass Aleph 3 amp
Cardas cables throughout
Audio Magic Mini Stealth power purifier for preamp and amp (turntable runs off a car battery)

Any advice appreciated!

Thanks,
J!

[Brian Cheney]

You can adjust the 626 bass by removing damping material from the cabinet.  To get inside unscrew the woofer.  Try taking a small handfull of fiberglass away, one speaker at a time.  Have fun, it works.

[J Harris]

Thanks Brian - I just tried taking a small handful of fibreglass out of each speaker and rescrewing on the woofer. It does seem to have made a difference to the bass tightness, amazingly.

By the way, either the fiberglass was packed more tightly up the top of the speaker on one than the other, or there was less fiberglass in there to start with - I had to reach way up into the left speaker, but in the right speaker it was actually already hanging down into the area behind the woofer. Should it all be stuffed firmly behind the midrange enclosure?

J!

[Brian Cheney]

Keep the fiberglass away from the port.  It is usually placed behind the mid subenclosure and tweeter.

Keep removing glass from the speaker that has more until you have the bass balanced.

[J Harris]

Hi Brian,

I actually stuffed the ports with socks on the advice of Jim Romeyn... it also seems to reduce the bass boominess, in my room.

Do you think I'd be better off unstuffing the port but removing more fibreglass?

Thanks again,
J!

[Brian Cheney]

Sutffing the port really detracts from the richness of sound typical of the 626R.

Removing fiberglass to taste will do the job nicely.

[J Harris]

OK, I've unstuffed the ports. I think I'll listen for a while, then remove more fibreglass if necessary.

Thanks for all the quick answers Brian

J!

[pjchappy]

Couldn't your sub (when off) be acting as a passive radiator?  Maybe that is your bass problem?

p

[Tyson]

Yes it definitely could.  The way to avoid this is to remove the sub from the room.  The other option is to leave it powered on, but to not send it a signal (ie, unplug the cables to it) when listening to music.

[Sedona Sky Sound]

The Pass is a fantastic amp so I hate to even raise the question, but have you tried the 626Rs with a different amp? It probably has nothing to do with your problem, but you may want to just try and borrow a high current, high wattage amp just as an experiment. This past weekend I experienced extremely loud, "thundering", uncontrolled bass when my 626Rs where hooked up to low power tube amps. The bass is also slightly looser using my Marsh amp than the Ampzilaa. Just thought I would throw out the suggestion.  

Julian
www.sedonaskysound.com

[J Harris]

Thanks for the suggestions, guys. The speakers are much less boomy with some fibreglass removed. I think further breakin has had an effect as well. I only have maybe 100 hours on them.

I take your point about the sub acting as a passive radiator. In fact I have turned on the subs at this point, with volume and crossover all the way down (60 is the lowest point on the crossover) and am achieving a nice balance. I have also toed in the speakers dramatically, crossing in front of the listening chair.

As the speakers break in further, I'll continue to experiment with subs/no subs, and different placements.

Re: the amp - Sedona Sky - yes this has occurred to me, and I'd definitely like to try a beefier amp. The Alephs are known for somewhat "loose" bass. I love the Pass sound though. Maybe an X150? Any other recommendations? No digital amps please though!

Thanks again,
J!

[John Casler]

Thanks for the suggestions, guys. The speakers are much less boomy with some fibreglass removed. I think further breakin has had an effect as well. I only have maybe 100 hours on them.

 I have also toed in the speakers dramatically, crossing in front of the listening chair.

Re: the amp - Sedona Sky - yes this has occurred to me, and I'd definitely like to try a beefier amp. The Alephs are known for somewhat "loose" bass. I love the Pass sound though. Maybe an X150? Any other recommendations? No digital amps please though!
...

Hi J,

Let me address these issues one at a time:

1) Break in may help a bit and it might be interesting to know where your pots are set.  

Try 11:00 - 12:00 if not there already.

I would also suggest "nearfield" (about 7 feet) with the 626Rs 7-9 feet apart.


2) I would also play with the toe in.  I prefer precision "100% on axis" and all my suggestions are based on that convergence.  This will cause the mids and highs to sound louder and more detailed and clear (so be prepared to turn the pots down even further)

3) As far as amps, the AMPzilla  2K is the best amp I have ever heard with the VMPS line.  It has some of the most controlled bass of any amp out there.

[J Harris]

Hey there John,

I have the pots set at exactly 12 noon right now - for a while I needed the treble higher, but no longer.

By on axis, you mean toed in so that the listener is exactly at the point of the triangle?

Ampzilla - at $2500 per monobloc, I'm afraid this is out of my price range!

Thanks for the tips --

Best
J!

[John Casler]

By on axis, you mean toed in so that the listener is exactly at the point of the triangle?

Yes... I am an "anti-room" freak.  In two channel audio, nothing can foul the original recording like room interaction.

By converging exactly on axis, you are almost wearing headphones, but again, do be prepared to dial down the pots because this is also the "hottest" of listening convergences.

As I mentioned earlier unless you have a fully treated room it is also best to listen "nearfield" so that at least the "precedence effect" in the brain over-rides most room effects.

And I might also mention that I have powered my 626R FSTs with a 60wpc Bryston with very adequate and smooth bass up to about 90db or so before it didn't have the "oomph" it needed.

But at 85 db it was tight and clean and dry.

And I had it sitting right beside my "depowered" RM40s (two 10"chers) without any problems.  I think your bass boom is one of two things (or maybe a combo of the two

1) the amp
2) the room

Good luck, and let me know how it turns out.

[Brian Cheney]

I repeat, the 626 bass is easily tunable by removing the fiberglass damping material from inside the cabinet in small increments, about the size of a cotton ball, at a time.

[J Harris]

Brian, just to be clear, I did remove small bits of fibreglass and unstuffed the ports. This has resulted in a more balanced bass. And it's tightening up the more hours I put on it.

At this point I'm also concerned that I'm not giving the speakers enough power. I'm curious to try them with a more powerful amp.

Thanks,
J!

[BrunoB]

You can adjust the 626 bass by removing damping material from the cabinet.  To get inside unscrew the woofer.  Try taking a small handfull of fiberglass away, one speaker at a time.  Have fun, it works.

I  have read in several place that stuffing inside the cabinet increases the volume seen by the woofer and gives deeper bass.

I wanted to have more bass with my 626R.

So, I removed the 25 g of fiberglass from my 626R and replaced it by 200 g (less than 1/2 pound) of Poly-fill spread all over in the cabinet (except the port). The poly-fill I used is much less dense than fiber glass and fills easely most of the space inside the main cabinet.  Unlike fiberglass and Acoustastuff, Poly-fill feels like a spring. It is soft and nice to work with.
The  result is a net increase in  the amount bass. I also have the impression than the bass is cleaner and  tighter. I like my 626R much better with the extra stuffing.

If requested, I can provide the manufacturer name.

Bruno