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

OP. Thanks for the report back. I would not have thought that was the problem. While more power helps solidify bass, etc. That big a difference is surprising to me. But, really glad you solved the problem. 
 

For power conditioners, they improve most folks systems, but occasionally they don’t… put yourself into the lucky category.

@dridel,

Bravo!! Glad you are happy now with the sound of the B&W 702's.😊This article came to mind on bi-amping speakers. Thought you might like it. In my experience I always found bi-amping to sound better then a single amp.

Mike

 

Glad you got it sorted but I would have never guess it was power. I have only used the Big Macs though and my MC462 seems to plow through anything hooked up to it. Maybe the lower powered Mac can’t handle the impedance curve. 

 

Vandersteen 2CE Signature III:

Recommended Amplification

40-160 Watts Into 8 Ohms

Frequency Response

29Hz – 29kHz +/- 3dB

32Hz - 21kHz +/-1.5dB

Sensitivity

86 dB, 1 meter with 2.83 volt input

Impedance

7 ohms nominal 4 ohms minimum

 

B&W 702 S2:

Power Range 30-300 
Frequency Response 46-28k Hz 
Sensitivity 90 dB 
Impedance (Ohms)

 

As I pointed out earlier the 46 Hz versus 29 Hz is reflected in the low freq trailing off in the link. So one would expect the 2C versions to play with more authority at the lower frequencies.

However the 86 versus 90 dB sensitivity, would favour the 702S2.

The “fact” that that same amplifier works nicely on the 2C can make us wonder if it is all in the more extended low frequency? Or if there is some load complexity that is also at play?

Does that MS252 have a variety of transformer tap impedance posts?
And was it using the 8 ohm tap?