Comparison of Polk SDA CRS+ with Boston Acoustics A400 -- Bass= SDA; Mids/highs=A400.

[Mystery]

Few weeks ago I bought a very nice pair of Boston Acoustics A400 (TOTL) .
All six woofers needed re-foam and one side of the MDF stand has some pieces crumbled but otherwise excellent condition.





Re-foamed them with OEM foam surrounds and everything turned out great.



So next logical thing to do is to compare.

Comparison with Polk SDA CRS+ -- Bass SDA; Mids/highs A400...
Polk SDA CRS+ -- 6 ohms; very small footprint; 12.75 H x 20 W x 10.23 D; needs stands.
35 lbs each; 1 tweeter, two 6.5 inch mid woofers and 10 inch passive radiator in the back.
Frequency Response: Overall - 24Hz - 26kHz . -3db is 42Hz to 20kHz.
Efficiency: 92 dB.
MSRP: $900

Boston A400 -- 4 ohms; pretty tall and wide; 41 H x 21 W x 7.25 D.
Compared to SDA CRS+, these are giants.
65 lbs each; 1 tweeter, one 6 inch mid woofer and two 8 inch active bass woofers;
Frequency Response: 38 - 25kHz (+-3dB)
Efficiency: 88 dB
MSRP: NO IDEA...
A quote from it's specs, "The combined radiating area of the two 8-inch drivers is equal to that of one 12-inch woofer."

From the specs, A400's with two 8-inch woofers should have better +-3dB low response at 38Hz compared to CRS+'s 42Hz.
But that's only in the specs.
I listened to multiple songs switching these speakers and SDA CRS+'s have extra low notes that A400 is missing.
The SDA 10" passive really adds a big thud/throw on bass that A400 just doesn't have.
A400 bass is tight/punchy and quick but not quite low. It is thunderous but the ones you hear close by without the soft thud from far away thunders.

However, A400 has really great mids and highs than CRS+.
It feels like all mids/highs are much more present, crispier and alive in A400.
CRS+ feels like little bit recessed/relaxed compared to A400.
After listening to A400 for few minutes and switching to CRS+'s, it feels like some strings/highs are muted/veiled or disappeared.

Keep in mind that both pairs have untouched crossovers.
I was planning on re-capping SDA's but haven't had chance/time yet that may improve mids/highs on CRS+.


CRS+'s only have 6.5 inch mids and a 10" passive and have much better lows than A400's with dual 8 inch active woofers. A400's may be designed like this not to throw bass but to have tight attack bass. Doing that could be the cause of completely missing low frequencies rather than reproducing them in low volume.
CRS+'s have that smooth bass recoil sound even though it's in low volume.
Also, I checked a track in both speakers and CRS+ mid woofer moves a lot in low frequency sweep clip all the way to the end while A400 woofers just stop moving few seconds before that low frequency clip ends. It appears that the crossover completely cuts low frequencies at a fixed hz point instead of a roll. Hmm...

Conclusion:
SDA CRS+ definitely win in bass department even though they are smaller than half.
Mids/highs go to A400's.
After testing I decided to move SDA CRS+ into the bedroom but then though of putting them on top of A400's so I can go back and forth if needed.
Since I can complement lows with a subwoofer if needed, A400's sound better for music vocals and movie dialogues. I'm liking A400's as home theater fronts as well as for music.
These don't have SDA effect but these sound like listening to live music.
They really bring all the instruments and vocals better than CRS+'s except the soft/low bass throw that CRS+'s have.
I set my tone to +2 bass and lows are much more coherent with mids/highs now in A400's.

Did anyone listen to both of these and have similar conclusion?
Thanks for comment.

[nspindel]

I've never done a comparison as you've done, but certainly crossover upgrades help the mids of the CRS+. I'm listening to my new ones right now and am in heaven.

[cnh]

Nice review, but it's kind of hard to believe the CRS+ puts out more bass than a BA A400. I have a set of BA A100s and they can produce thunderous bass in a smaller cabinet with the same tweeter and a 10" woofer? The mids are a weak point though, which one would expect the A400s to have no problem with. As you may know the A100s were B.A.s no holds barred contender to the Large Advent and pretty much spec close to the range for the A400s.

A friend of mine has the A200s (one model down, 3 way with one 10" sub) and they sound pretty darned good! Not that the CRS+ are not also good.

I am a little puzzled, because I know what kind of bass my SDA 2Bs can put out, and the A200s are closer to that.

cnh

[F1nut]

Do the 4.1TL upgrade to the CRS+. The RD0198-1 is a much better tweeter than your SL2000's or the RD0194-1. The result will be improved highs/mids.....no more of, "it feels like some strings/highs are muted/veiled or disappeared."

[Mystery]

I know it's really amazing how much bass CRS+ produce.
BA A400's have very narrow cabinets and "New England" sound that usually don't have much bass.


Few at AK also concur CRS+ have more bass than A400 so it's not only me.
A400's don't have that follow through recoil bass.
Bass is punchy and strong/thunderous but ends right there without a long follow through while CRS+'s have that soft long throw you can hear softly in decreasing volume and definitely much lower frequencies like subwoofer sound.

BA's lower series like A150 may have passive radiator that acts as port and may be that's the cause of more/lower bass. Hmm...

[gmjungbluth]

I have a pair of the A200s that I'm actually trying to sell - I like them but they are too big for the space I was using them in - a long and narrow room - I think these need more space and a lot of wattage to really wake up. I had them hooked up to a vintage Pioneer receiver and got good bass out of them. With a newer Harman Kardon there was less bass. But then again it could have been the acoustics of my room as well...

[motorstereo]

I also had the same results comparing my crs's to my recapped ba400's. But what really surprised me is when I compared my 90lb klh 12's to the little crs's. Those diminutive little polks which are about 1/4 the size of the big klh's shamed the much bigger klh's pretty badly overall and really bad in the bass dept. Polk got things right with these little wonders.

[nspindel]

I also had the same results comparing my crs's to my recapped ba400's. But what really surprised me is when I compared my 90lb klh 12's to the little crs's. Those diminutive little polks which are about 1/4 the size of the big klh's shamed the much bigger klh's pretty badly overall and really bad in the bass dept. Polk got things right with these little wonders.

You sure got that right!

http://www.polkaudio.com/forums/show...s-are-complete!

[Mystery]

...
I had them hooked up to a vintage Pioneer receiver and got good bass out of them. With a newer Harman Kardon there was less bass. But then again it could have been the acoustics of my room as well...

That's something I have to try. I'm running them off of a 7.1 HDMI receiver.
May be bi-amping will bring their bass to a nice level but I still doubt they'll go any lower than what they are designed to do.

[tophatjohnny]

Great comparison. I will be adding new totally updated CRS+'s to my SDA 2B's in the bedroom. Can't wait.

[PolkieMan]

Good write up.
The CRS will win in the SDA department and properly positioned on stands with the just the Rdo-194 replacement I wonder if that could change your mind.

[Mystery]

Great comparison. I will be adding new totally updated CRS+'s to my SDA 2B's in the bedroom. Can't wait.

I have them around 10 inches from the back wall and sound great.

Good write up.
The CRS will win in the SDA department and properly positioned on stands with the just the Rdo-194 replacement I wonder if that could change your mind.

Ya, I may have to borrow Larry's tricked out pair to compare the mids before I do mine.

[gmjungbluth]

Are the A400s bi-ampable? My A200s were not - they had the old-school screw-down connectors. If I was going to keep them I would have put in some new posts.

That's something I have to try. I'm running them off of a 7.1 HDMI receiver.
May be bi-amping will bring their bass to a nice level but I still doubt they'll go any lower than what they are designed to do.

[motorstereo]

deleted

[motorstereo]

You sure got that right!

http://www.polkaudio.com/forums/show...s-are-complete!

Excellent job and kudos for the great write up as well. I'll be interested (as I'm sure everyone else here will be to) in your before and after thoughts.

[Mystery]

Are the A400s bi-ampable? My A200s were not - they had the old-school screw-down connectors. If I was going to keep them I would have put in some new posts.

Yeah oh yeah! :)
Here you go:

[gmjungbluth]

Great pic!

[dkr919]

BA's lower series like A150 may have passive radiator that acts as port and may be that's the cause of more/lower bass. Hmm...

Congrats on the A400's.

The A150 is indeed a SEALED acoustic suspension 3 way speaker. I bought my set new in the early 80's and recently compared them to some Polk 7c's and Magnepan MMG's I had acquired.

IMO the A150 sounded more natural with very tight thumping bass than the 7c's. Switching between the two the 7c's are very good but had a more bloated sound and the tweeters were very fatiguing at moderate to high volume levels.

Comparing them to the MMG's they were only slightly less natural and detailed(very close) than the MMG's with the A150 having superior bass.

I was somewhat surprised with the results because the A150 really doesn't get much acclaim.

[Mystery]

I changed setup today and listened to CRS+ and they sounded much better than when I compared against BA A400's.
They didn't lack in mid/high compared to BA A400's that I noticed before.

It could be the setup/different amp or just because they will be gone soon.

[gmjungbluth]

And I just demoed my A200s this weekend in a back-to-back with some Polk 7cs I am also trying to sell. This is the first time I had these speakers in the same room for a test. Also had them in my basement, which is set up for HT and has better acoustics than the living room where I had the A200s before.

The A200s still seem to like watts, and for their size they don't put out as much bass as you would expect - I actually re-wired them once to make sure I didn't have them out of phase. The bass is there, just not as 'massive' as you would expect for a speaker of this size. They get down really low - on a passage from Swan Lake they were reproducing the Cello and Bass parts amazingly, but there is no modern 'thump'.

Compared against the Polk 7cs, it was no contest - the polks sounded like they had a layer of cloth draped over them - the Boston's mids and highs were fuller, richer, and higher.

Now I have a dilemma - the A200s are beautiful, and sound great (in my basement) but I was planning on selling them and the 7cs, and recapping all the polks in my surround sound setup - 7As front and 5As back. But now I'm thinking about whether it would be better to try and shoehorn those A200s on either side of my projector screen and rethink my all Polk Monitor HT setup.

too many speakers, not enough ears!!!

[Mystery]

The bass is there, just not as 'massive' as you would expect for a speaker of this size. They get down really low - on a passage from Swan Lake they were reproducing the Cello and Bass parts amazingly, but there is no modern 'thump'.

A400's supposedly are better than A200's in bass department.
Boston's have great mid/high and even bass is thundering bass but they lack soft thump that Polks have.
To get best of both worlds, I use both as my fronts and switch them with a speaker selector whenever I feel like listening to one vs other.

[gmjungbluth]

An update to my A200 saga...

I'm holding on to the A200s and preparing to swap them out into main duty in my HT system - I am debating about putting new binding posts in or putting modern 5-ways on - my HT cabling is all 8 gauge with banana plugs. Looking inside the A200s it looks like the binding posts wouldn't be too hard to replace, but a bit messy with a lot of glue-gun residue to clean up first.

Another discovery while looking inside my A200s - the woofers are imposters!! Someone before me replaced the original A200 woofers with some aftermarket jobs- GRS 10" paper cone woofers. Looking on the Parts-Express website, these are the cheapest they sell.

Here's a link:
http://www.parts-express.com/pe/show...number=292-410

Now I know why the bass isn't right in my speakers. In addition to being a replacement, the stated sensitivity of the GRS woofer is 87db/watt. Since the original A220s were measured at 90db/watt, I'm thinking that right now the new woofer's bass output is much less than the original. It's still there, but you need more power to get it going.

I really like the A200s for the mids and highs, and I can get thumping bass out of them now as-is. But now that I know what's in there it's bugging me. More researching online found that the Dayton Classic 10" woofer is almost a perfect match for the old Boston 10", and is also available through Parts Express for about $30 per. I may go for it just to put my mind at ease.

Along the way I also picked up a pair of Boston A100s, just like my 200s in oak with the blonde grilles. If my 200s are a 9/10 cosmetically these are a 7 - still very presentable. they have the later dome tweeter and have been refoamed. I demoed them against my Polk Monitor 7As with some classic rock and piano music. Overall the presentation is very much the same. The soundstage on the Polks may be a bit wider, but the Bostons hit with more and fuller bass, and the mids and uppers seem fuller - this is where the Peerless tweeter really starts to sound laid-back. For a two-way the Boston A100s sound really good.

So now I'm thinking that I'll move my Polk M7As and 5As onto the workbench for recapping (and maybe re-veneering) and let the Boston A200s and A100s do HT duty. I thought about moving the original 10" Boston drivers from my A100s to the A200s but thought against it - best to keep the original design drivers intact in the 2-way system, where woofer-tweeter matching is more important.

[Mystery]

An update to my A200 saga...
Another discovery while looking inside my A200s - the woofers are imposters!! Someone before me replaced the original A200 woofers with some aftermarket jobs- GRS 10" paper cone woofers. Looking on the Parts-Express website, these are the cheapest they sell.

I really like the A200s for the mids and highs, and I can get thumping bass out of them now as-is. But now that I know what's in there it's bugging me. More researching online found that the Dayton Classic 10" woofer is almost a perfect match for the old Boston 10", and is also available through Parts Express for about $30 per. I may go for it just to put my mind at ease.

I'd look for correct original woofers in ebay first if you can find them.

The A400's have better bass now. May be the new surrounds needed some burn in time.
Bass is less when you are right up close but it grows louder farther away.

[Schurkey]

Another discovery while looking inside my A200s - the woofers are imposters!! Someone before me replaced the original A200 woofers with some aftermarket jobs- GRS 10" paper cone woofers. Looking on the Parts-Express website, these are the cheapest they sell.

Very important.

It is absolutely pointless to compare speakers--or anything else--without first verifying that the items being compared are in proper working order. Until they're proven to be functioning properly, there's no validity to the comparison. This is doubly-important when testing "aged" items, not only are all the original design and manufacturing compromises still there, but the ravages of time and slovenly maintenance/repair also affect the outcome.

The Wise Man once remarked about improper-protocol audio comparisons being similar to "tire testing without a pressure gauge".

http://www.avahifi.com/index.php?opt...3d59dc16ac9c12

[gmjungbluth]

Yep - good point. They did look so close to the originals that I never bothered to pull them open to verify. If there had been any glaring deficiencies I would have.

And in the end I know my comparisons only really work for the gear in my basement - my old Polks and Bostons (and receivers and other speakers) don't necessarily sound like anyone else's, due to aging capacitors, drivers, cabinet sealing, placement, pairing with equally-aged amplifiers, and any number of other variables. But those comparisons are important to me because I'm the one listening to all that stuff and deciding what will stay and what will go.

RE Mystery's post about looking for the proper woofers on eBay - I'll keep my eyes open and it will depend on the final cost - someone has a couple of them up there right now for $99 - far more then I would like to spend. As it is, I'm planning on pairing the A200s with a subwoofer in my HT setup so I'm in no hurry really to put a ton of more money into these until I have to - I have a few more speaker projects that are (or at least were) in line before these!

Very important.

It is absolutely pointless to compare speakers--or anything else--without first verifying that the items being compared are in proper working order. Until they're proven to be functioning properly, there's no validity to the comparison. This is doubly-important when testing "aged" items, not only are all the original design and manufacturing compromises still there, but the ravages of time and slovenly maintenance/repair also affect the outcome.

The Wise Man once remarked about improper-protocol audio comparisons being similar to "tire testing without a pressure gauge".

http://www.avahifi.com/index.php?opt...3d59dc16ac9c12