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Underpowered?

Hi guys.  Newbie here asking for advice. 

I recently purchased a pair of B&W 702 Signature (8Ω, 30-300W, 90 dB) to replace my old faithful 683s (8Ω, 20-200W, 90 dB).  I am running them with a McIntosh MA252 (100W into 8Ω, 160W into 4Ω).  I purchased them thinking they would complete my end-game system.  However, my excitement turned into disappointment when I realized the lows were somewhat lacking.  For all their faults, the 683s had a great dynamic low kick (no sub) that I was looking to take one step further.  Unsurprisingly, the highs and mids on the 702s were indeed more detailed and separation was clearer, but I couldn't get over the uninspiring lows.  I found myself listening at higher volumes chasing for that bass oomph.  Neither playing with the EQ at the source nor the amp was satisfactory.  So, I did the research that perhaps I should've done before purchasing the 702s and found out they are quite power hungry despite the specs being similar to the 683s.  I emailed B&W and McIntosh and they agreed the amp is probably underpowered for the 702s.  B&W described the sound of an underpowered speaker as one lacking low response and details, which is spot on. McIntosh suggested the MA352 (200W into 8Ω, 320W into 4Ω).

Of note, I love the MA252 and really wish there was a way to make this work.  I don't need a DAC/streamer/etc so I'm happy to put all my money on better sound vs tech features.  But I also think the speakers sound amazing even when somewhat underpowered and I'm considering upgrading to a MA352, Michi X3, Hegel 390.  Another option could be to get a sub? But I feel that would defeat the purpose of having a 3way standing speaker and then I might as well get a pair of bookshelf speakers (805 D4s, LS50 metas?).

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!

dridel
dridel OP
15 posts
 

After a long weekend enjoying my dealer's MA 352, I went to return it today.  I also asked them to check my MA252 for problems, since many people here felt it should be able to drive the 702s. They confirmed the issue is just that the 702s need more power.  I wanted to audition the Michi X3, but they didn't have one in stock and they were very confident the MA352 is the superior amp.  So, I pulled the trigger and took the MA352 home.  I also bought a Panamax MR4300 even though I'm not 100% sure how much effect the power conditioner had on my setup.

The MA352 + 702 Signatures combo gets me very close to the best setups I have heard at dealers for much less money and before even playing with speaker positioning and room treatment. Let alone upgrading my DAC, cables, etc. I know I shouldn't say this, but I really think this is it for me.

Moral of the story: make sure your amp has AT LEAST HALF of your speaker's maximum rated wattage!

david_ten
5,480 posts
 

Hmm... I must be highly immoral. The 3 watts of my amps are (at max power) 7.5% of maximum recommended power (40 watts), for my speakers. Or 15% of half power (20 watts).

Moral of the story: make sure your amp has AT LEAST HALF of your speaker’s maximum rated wattage!

 

Your story. Your morals. : )

Happy you’ve found a pairing to your liking and are enjoying it!!!

james633
1,042 posts
 

Probably has more to do with the impedance than anything. 
 

I use a power conditioner. The only thing it helps is my JL subs… because they are junk and super noisy with what appears to be zero AC filtering. Everything else it did not help or made it worse. Just have to play with it. 

asvjerry's avatar
asvjerry
4,691 posts
 

@mozartfan ...*friendly back pat*  No, no, no....

If you intended to or not, to hijack a forum one needs either a subtle yet devious approach,,,;)

Otherwise, one's left with just the 'in your face kamikaze dog waste paintball splatter'.

Crude, yes.  Might get jerked off the forum by the Brain Police.
They email a nice note to 'not do that '.
They deserve that....having to actually 'police' all the forums fomented by all of us has to have some form of retaliation.

Class dismissed.  Be sure to scan Chapter 6.66, the 'Trollish Entertainment? Or Sociopathic Pseudo-Ironic 'Civility'.

There always a pop-quiz....everyday....😏

jjss49's avatar
Ag insider logo xs@2x
jjss49
6,612 posts
 

Moral of the story: make sure your amp has AT LEAST HALF of your speaker’s maximum rated wattage!

i would say this is not a general truism... the central issue here, in this case, is the nominal impedance rating given by b&w (no doubt by their marketing department...) is b-s...

see the test results of the b&w 702s2 as measured by john atkinson at stereophile...

I used DRA Labs’ MLSSA system and a calibrated DPA 4006 microphone to measure 7the Bowers & Wilkins 702 S2’s frequency response in the farfield, and an Earthworks QTC-40 for the nearfield responses. My estimate of the B&W’s sensitivity was a high 90.2dB(B)/2.83V/m, confirming the specified 90dB. The 702 S2’s nominal impedance is specified as 8 ohms, with a minimum value of 3.1 ohms. My measurement of the impedance magnitude (fig.1, solid trace) reveals that while the impedance does lie at and above 8 ohms in the low treble and in two regions in the bass, it actually drops below 6 ohms through much the audioband, with a minimum value of 3 ohms in the upper bass. There is also a current-hungry combination of 4 ohms and a –48° electrical phase angle at 88Hz. Although technically this is an 8 ohm design, I think it should be used with amplifiers that are comfortable with 4 ohm loads.

this is why the smaller mac amp had so much trouble with the speaker in the bass region, when you see a solid state amp unable to double 8 ohm rated power into a 4 ohm load, it shows the amp has shortcuts inside, limits current capability into low impedance reactive loads ... so details matter, specifics matter... generalities are meaningless

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