Underpowered?

A powered sub or two would take care of the bottom octave! 

Try moving the loudspeakers around the room.  There might be a location where they lock-in better.

try using another Tap on the amplifier if you using 4 ohms tap try the 2 or 8 ohms

I agree with one or two powered subs. Two is better than one IMO.

Wow that amp should be enough power I would think. 
 

Maybe the 683s have a bass “party” hump that you are used to? 

I just looked at the specs.  There's a combination of fast roll off below 100 Hz (pretty high for a floor stander!) and an impedance dip there at the low end.

I'd strongly suggest you measure your room before making any adjustments, but I would not be surprised if you are a very good candidate for a sub. 

You'll want something with some built in DSP capabilities to help you manage room modes, and, as always, consider room treatment before you do anything else.

Actually I just thought of a combination for you to try. Plug the ports and move the speakers closer to the wall. Plugging the port will damp the peak at 100 Hz but more importantly slow down how fast it rolls off below that.

If they still sound anemic, you definitely need a higher current amp (not necessarily more watts, more watts in the bass).

If they suddenly improve, but you still want more bass a sub is a good option.

I have some friends who use the new Vandersteen Sub 3 over their previous REL in that situation since they design them to keep the sound of the main amps so you can tell where they cross over , plus that takes the load under 120hz away from the main amp and speakers.  Speakers and a,ps get the advantage here. They are also fully adjustable for the room with a built in 11 band EQ. Just a thought. Designs change and maybe the newer speakers just don’t kick like the older ones. No idea there. Good luck 

op - a few thoughts

1. speaker placement and room loading is key to getting good bass response, try that in all reasonable permutations before changing equipment

2. treble and midrange clarity will always seem enhanced when there is less bass foundation (or bass boom)... those things are highly interrelated... trick is to have cake and eat it too

3. subs can certainly help (a pair ideally), rel’s are very good, others are good too - but note point #5 below

4. the mac 252 should have ample power and grip to drive the b&w’s -- you can try a different amp (a hegel is what i would try if you go that route after doing point #1), but i suspect things won’t change too much

5. there is a recent thread on big vs small (satellite type) speakers... that may be a good read for you... bottom line is big speakers sound bigger, it is not just the deep bass, it is how air is moved, and midrange and midbass is presented in a much more easeful, enveloping, full, rich way... that is the difference

good luck

1. Sell the 702s and look for a better match for my MA252?

Dang, you got yourself in a tricky situation. There is no easy way out. I'm not a big McIntosh fan but the MA252 is a neat unit and 100wpc is enough if you are not trying to wake the neighbors. Perhaps some Triangle Delta loudspeakers (or other easy to drive loudspeaker). not a huge step up in efficiency but they will sound good at lower volumes, but you still might need a sub.  

+1 work on speaker placement

if not

+1 add two sub woofers… always add pairs… they will also extend soundstage as well as bass. Most recommended brand is REL.

I am also not a Mac fan, but it should have enough power… maybe Bo up a level in speakers, B&W is not know to lack bass and a frequently paired with MAc.

@dridel,

JMO: I would keep the B&W 702 speakers and the McIntosh MA252 amp. Then buy a second amp to BI-AMP the B&W speakers. That should improve the bass. Also, are the foam plugs in the rear ports? If yes, I would remove them.

B 4 you do anything, check the connections on the back of each speaker. Are they connected to the lower terminals? If not, that may be the reason they are lacking bass.

@dridel 

You have fantastic speakers in the 702 Sigs. Yes, they need more power. I never heard everything my 683 S2s could do until I got a Rotel RB-1590 350 watt amplifier with a huge power supply to drive them. 

In a small room with a lot of boundary reinforcement the MA252 would probably be adequate but it still wouldn’t handle the three woofers well on the 702 Sigs.

Good luck with your decision. Don’t give up on the 702 Sigs to quick, they are amazing.

 Cheers,

Scott

@jjss49 I agree 100% on your statement regarding satellites v floorstanders. The bookshelves just don't move enough air in my room.

Two good subwoofers will definitely get you the bottom end your looking for and probably the cheapest option at this point. Upgrading the amp will definitely be expensive but if you really like the bottom end well thats what subwoofers do very well if you have quality subs.. GOOD LUCK!

Can you try out or borrow a beefy amp to tryout? 

I have a McIntosh MC 2500 I'll be soon parting with if it's power you want!

Make sure you run them for at least 200-300h at regular listening volume (65-80 dbC) for full break-in before making any final conclusion... May not be a problem of amp power at all. Also, if you are not bi-wiring them, at least use good bi-wiring cables with similar quality to your speaker cables, not the standarf jumpers provided. Hope this helps.

If you go with  subs, you will need an active crossover or DSP to roll the lows off your 702’s. Then the Mac will have more than enough power!
I still have an ancient audio research crossover for such needs.

All the best.

JD

Upgrade the Mac MA252 to the 352.   I recently purchased the 352 to replace my MA6900.  It 's power is 200 watts into 8 ohms, 320 watts into 4 ohms.  A doubling of power over the 252.  And it has 5 equalizer buttons, just like my former 6900.  It is basically a more powerful 252 with equalizer buttons.

Of course McIntosh suggested you need a higher powered amp from them. 😏 I'd also say a subwoofer would be preferable to buying a different amp that probably won't make any objective difference whereas a sub most definitely will.

So what do you guys think? Is it normal for a speaker that’s rated 30-300W to be underpowered with a 100W amp?? What would you do:

1. Sell the 702s and look for a better match for my MA252?

2. Upgrade the MA252 (MA352? Michi X3? NAD 33?)?

3. Get a subwoofer?

I would really appreciate your thoughts/advice!

#1 - do you like the speakers?

#2 - Those Purifi Eigentakt do not look as good as a Mac. But they likely have the cojones.

As ​​​​​​@ctsooner mentioned there is the Vandy sub, which is sort of an active alternative to the DSP based approach. And that folds back into #2 as some load is relieved off of the speakers and amp.

I know nothing about the B&W, but are you smitten with them?
If not there are probably some other options.

They do appear top be a bit weak on the lower registers:

can't believe it's not enough power unless you're in a monster size room. Systems have oomph if they're dynamically linear and that can be limited by a speaker with a lousy impedance load and/or an amp that can't handle the load. My gut feeling is it's the speakers.

A common recommendation for non-dynamic speakers is to add power and play loud. This doesn't really provide linear dynamic level changes but loudness compensates some for a lack of life in reproduction.

Reading all this discussion makes it all the more clear that the gear is as much an instrument in the music you listen to at home as anything that's recorded on a given disc. Talk about transparency or neutrality or specifications is kind of bunk. A stereo is a machine that makes the music sound better. 

can't believe it's not enough power unless you're in a monster size room. Systems have oomph if they're dynamically linear and that can be limited by a speaker with a lousy impedance load and/or an amp that can't handle the load. My gut feeling is it's the speakers.

That plot labeled “graph 5”  in the link looks like -5dB at 100Hz... and headed south.

Before you change equipment I too strongly recommend playing with speaker placement AND listening position. I too had this exact same issue when I got my floorstanders (Spendor D7.2) and thought a sub could fix it, it didn’t sound ‘better’, I could just hear an exaggerated boomy bass that was separate to the speakers. So I spent hours moving the speakers around and at the same time moving my listening position around. What you might have is a null where you are sat which is cancelling out the bass. If you find standing in different places gives you more bass, then there is bass in your setup, you just need to find the listening position coupled with speaker placement that is the bass sweet spot. I have the Hegel H390 and personally love it, the bass it produces has a wonderful tone that is addictive. I am not suggesting it is THE amp or that it will improve things, just that I’m a happy owner of one of the amps you mentioned.

Room treatments will help the bass response further but just make sure if you are going to use them you get something that will actually make a difference. For the lower frequencies it is all about the depth of the trap, thin traps will do nothing to slow down the lower frequency waves which can be cancelling each other out.

Finally once I had found my preferred speaker and listening position, I purchased a basic app called HouseCurve and that was a super cheap way to get some feedback on the in room frequency response. This app is in no way professional like REW, however it did give me the frequency ranges that I had bass dip in which I then boosted with parametric EQ and reduced slightly the upper frequency peaks. Together that massively balanced out the sound bringing the bass through even more. If the highs are dominant you’ll notice them more and reducing them slightly can bring through more bass perception.

My big takeaway is there is a lot you can do, which really is the fun of owning a system, the tweaking and trialing things. Simply replacing the amp may not bring any improvements if it’s actually the room and placement of speakers and seat that are the issue. Try all of the above first and if there are no improvements then you may need to upgrade. I’m from the UK and we tend to try and not run subs, your floorstanders will have enough bass and it is better (imo) to get it out of them rather than just over-boosting the bass with subs that aren’t integrated properly. I now don’t use a sub for music as my setup has it all following the work I carried out above, the sub only gets turned on for films and at this point only provides rumble.

@dridel Congratulations on your new speakers! 

I grappled with a similar problem over the past three years. Having moved to a new house my B&W801M S2s didn't sound the way they used to. I upgraded the XOs, then the preamp. Had my Krell KSA-250 recapped. All to no avail: the bottom octave was still AWOL. Then I had a lightbulb moment: maybe the problem was the room. I lugged one of my BK subs downstairs and hooked it up. Result! The bass was back.

Ordered two new subs and dialled them in. Now the system sounds better than it ever has.

I reckon your room doesn't play nice with the new 702s. They aren't speakers that are hugely difficult to drive, I don't think your MA252 is the problem and a new amp is not going to fix things. If changing the 702s' room placement doesn't improve their bass response and apart from that you like they way they sound, the quickest, easiest, and most satisfying way to address that issue would be to install two subs. Been there, done that...

REL (and BK) subs feature a high level connection which I prefer for a two channel connection. You do not hear my subs, you only feel their "foundation", along with a wider, deeper sound stage. A friend who popped in for a listen didn't even notice them sitting in the background as the music was playing...

Good luck!

Adding subs will be my number one ☝️ choice or buy Class D amp to bi-amp

Class D for lows and McIntosh for highs 

Tricky situation and logical way out not always a help. If you was satisfied with your three way sound signature adding subs could not be solution. I would go with amp or speakers replacement. 

The first thing to do is if you have standard wires, you will need a jumper if there is 4 posts and you have 2 wires to connect( plus and minus)

Second, play some music walk around the room.  Do you hear boomy bass in some places and none in others.  Go to the corners, is it boomy there?  If you hear this then you should try moving your speakers around.  I point them right at me and sit back the same distance as the speakers sit apart.  Some speakers only need to be tilted in slightly.

Third, even if the room is not too bad for acoustics, a sub is a real helper here.  Very few speakers go down low enough  in the bass.  Especially, since you said you liked bass.  But you may find once you fix positioning and room problems your speakers are OK.  Try sitting a sub right beside a speaker.  Point it toward you or the wall.  If you have a second sub put it along the wall by you. 

Fourth, you are used to the B&W sound so I would not ditch these speakers...yet.  Same with the amp.  Depends on how loud you like your music.  But amp replacement is after you try a sub.  A powered sub has it's own amp and bass takes the most power, so your 252 may be enough.  Also, less excusion of the woofers reduces distortion of midrange frequencies.

Don't feel bad, they always say build your system around your speakers.  :)

I ran into a very similar thing but I knew that lack of power had nothing to disclose with it. Started out with what turned out to be an amazing thing I bought a pair of furutech wall outlet plugs all of a sudden I had some base out of my Levinson 33s. I then put a set of furutech plugs on the end of the captive power cords better again. Then I fooled around with room placement. Each time I got more base. Also thinking of you have two sets of binding post on the back of the speaker's it is time to replace the flat tin jumper bars and go to a true jumper. Easy to get that  before you buy just try it with some copper wire of a heavy gauge of you think it does a bunch then get a good one. Also I bought a cable break-in ma home that was made by siltech that made a huge difference on every piece of wire on the system. The tonal range got bigger at bother ends. It didn't matter if the wire had been used regularly for twenty years. The range got bigger the sound fuller etc. When you setup the room I personally like the speakers setup on odds vs evens. On evens you tend to accentuate mid bass. A real rock and roll set up the speakers a quarter of the way into the room and a sixth of the way from the side of the room and the chair a quarter of the way into the room from the back wall. Personally I set the speakers a their of the way onto the room and a fifth for the side walls. I Then.make fine adjustment from either one of those places. Make sure the speaker s are level to each other  and they are at the exact same height.  Do you have spikes down to the floor? Did you change any placement of the gear? Different stands can make a huge difference as well. Personally I think your base is there you just have to find it. 

Regards

The upgrade to MA352 will provide a modest improvement in SQ based on power, but dialing up the low bass EQ is a targeted solution for the better damped woofer alignment in the 702 Sigs vs. your old under damped 683s. Adding a REL sub instead of the amp upgrade is too, and depending on which model and what deal you can get on the Mac, may not be as costly. If your room permits various subwoofer placements that approach has the advantage of letting you optimize speaker placement for overall imaging, and sub placement for bass loading. The spot where the speakers deliver better bass may not correspond to where they image best. 

100 watts is plenty...BUT:

I think you need an amp that doubles down on the power with halving of the impedance. Or at least close to doubling.

Some amps will deliver 100 watts at 8ohms and 200 watts at 4 ohms and are stable down to 1 ohm.

An amp like that will not waiver with a big impedance dip.

You can also go further up the McIntosh line to amps with autoformers.

Monoblocks would help too.

And yes, I would also look at speaker placement.

KISS

All great advice (esp, placement) but regardless a sub or two will add significantly.

Wow, many thanks to everyone who shared their opinions and experiences! It's so great to be part of this community and I only hope others also benefit from this post.

I'm surprised to see that there are solid arguments for each of my 3 options and that this problem might have multiple solutions. It seems the most recommended changes are by far positioning and adding a sub, followed by upgrading the amp and lastly replacing the speakers.  I will start by trying the simplest/cheapest ones first.  BTW, I brought back the 683s and yes, they are fuller, richer, more balanced and with a nice low kick.  The highs aren't as detailed and the 683 miss some extreme high frequencies that are not necessarily missed in music.  Overall, I seem to like the 683s better... Could it be that speakers sound better after a few years?? I know the 702s have great potential, so this makes me think there's a problem with the 252+702 pairing more than the speakers themselves.

Another aspect of this is that the issue doesn't resolve with high volume, which yes, comes with a better bass response but at levels where the highs are too piercing and fatiguing. The amp and speakers ARE capable of getting to good bass levels, but not in balance with the rest of the frequencies. That to me suggests the amp is underpowered since I doubt the speakers were made to be this skewed.

I will definitely play with positioning and report back. The speakers are fairly close to the wall as is.  Exact same position the 683s were in and never had a problem.
The ports are open with no foam plugs (I'll try plugging them and moving even closer to the wall).

Speaker cables are going in the lower terminal with the metal jumpers that came with the speakers. The amp only has 2 output terminals.  Is there a benefit to cables that go from 2 to 4 terminals?

Break-in: I doubt that's the issue but I will continue to listen and hope for an improvement. I also found some youtube break-in tones focused on lower frequencies that I could leave on for a few hours.

The B&W advisor's exact words were: "The 702 Signature speakers are rated for up to 300 Watts. Using an amplifier that outputs at least half that (~200 Watts or so) will allow you to get great performance from the speakers." So I will ask my local dealers to see if I can borrow a amp that's at least 200W per channel (min wattage recommended by B&W advisor). I will also try a sub.

@phantom_av: interesting suggestion but i checked and there's only one pair of speaker output terminals labeled 4/8Ω.

I am not necessarily tied to the 702s, but I loved everything about the 683s and was looking forward to simply improving everything about them.  I still hope I can get there!

Thanks again to everyone!

Daniel

I would guess buying a new amp will not work, you are chasing a ghost. The speakers have no low bass, look at the stereophile measurements below. I owned the 703S awhile back and ran it off a vintage (1976) 40 watt Marantz and it was fine. I would add subs with a highpass or buy a more well rounded speaker.

I run much larger speakers than the 702s2 and still run duel subs. Subs done right are always better than no subs. Even wilson audio makes giant subs with external crossovers for their giant speakers. There is a reason, it is alway better with subs.

@dridel,

This review just came to mind!

I’m a Mac fan and I’d say stay with Mac gear. If you need more muscle, which I can’t believe with a Mac, maybe you should think about pairing it with a larger amp. 

Mac amp of course. 

I would not trust Andrew Robinson’s opinion. He seems to lack highend experience or be a paid shill, I am undecided. No hard feelings toward the guy but you will get better advice here.

@james633,

understood!

A pair of REL S2 SHO Subwoofers would solve the problem.  Take some of the weight out of the towers and create a better sound stage.

The combo of MA252 and BW 683 S2 (raved by Stereophile) is the first 2-channel I have auditioned. I was satisfied by, in particular, its full/sweet midrange but somehow the mid-bass is a bit boosted/muddy and the bass note is neither tight or fast to my liking. In terms of Lab measured freq. responses, they were both rated down to 30Hz (683) and 28 Hz (702) but those are at -6dB. At -3dB, they were only at 52Hz (683) and 45Hz (702) despite of being a floor stander. Basically, for both models, the mid-bass is boosted before rolling off at a rather deep slope. Later I switch to different I.A. with higher wattage/current, same story and that leads me to believe the speaker is the weak link. I guess you just need to identify another set of speakers that have well-defined bass notes to your taste.

you should burn both the amp and the speakers, if they don't pair well, it's possible they just refuse pairing. 

Another aspect of this is that the issue doesn’t resolve with high volume, which yes, comes with a better bass response but at levels where the highs are too piercing and fatiguing. The amp and speakers ARE capable of getting to good bass levels, but not in balance with the rest of the frequencies.

Years ago, I had a similar problem with my Thiel cs1.6 and cs2.4, the cs2.4 that I bought used at this site had weak bass compare to the cs1.6 in my system!

I perform a battery test and found out the culprit was one of the woofer wired reverse polarity.

@james633 totally agree about his reviews, you just have to look at how he raves about the Auralic Altair G1 as the best streamer available which is a paid review. Nothing against Auralic, I own the ARIES G2.1 and love it, but the minute you put a review out like that as paid, it undermines everything else.

@dridel from your further comments it does sound like there might be a synergy issue here if the highs are unbearable, however B&W are known for having a bright treble (from the many reviews and conversations with dealers) which will become more apparent higher up the chain as it becomes more resolving. However it is worth trying the free stuff first before changing gear. You may also want to hang duvets and get more soft furnishings in your room if it’s got a lot of bare walls at the moment to see if it’s the reflections that are emphasising the treble. Just worth trying all the easy free stuff first before buying more and becoming disillusioned if it doesn’t fix it, as the sound you are after is out there!

@dridel

Neither playing with the EQ at the source nor the amp was satisfactory.

What sort of EQ options did you have at the source and at the amp?
 

How about some measurement like an REW graph of the left and then the right channel? (And finally both)

That would answer a lot of questions, including @imhififan woofer issue in the Theils.

There is no easy way to make a rational decision on multi k$ changes to fix the problem, without first having some factual way to understand what is (or maybe) the problem.

1. Have they had a sufficient break-in period???  2. As someone else suggested, you may want to place an ad here or on Craigslist to see if someone has a higher-powered quality amp who wishes to audition the 702's before pulling the trigger on them.   Not a big fan of subs for 2 channel towers, prefer them with HT.  A $7500 pair of towers shouldn't require a sub-woofer if sufficiently powered and broken in, unless in a huge room...

 second amp to drive the woofers. use the pre outs to a mac amp thats rated with 50% more power than the current amp and slave it to the woofers.