Wednesday, November 5, 2008

PSB Stratus Bronze review

Well another election has come and gone. Looks like we're in for some more 'big government' programs coming down the pipeline. Needless to say I'm not a fan - bureaucracy invites corruption, sloth and becomes a permanent part of 'the system'. Maybe I'm just old fashioned but I believe in self-reliance, hard work and privacy.

Well enough of that - here is my review of the PSB Stratus Bronze speakers:

After the creation of my single ended EL156 amplifiers, I needed to buy a pair of speakers that would work well with a minimal of wattage. Sure I own a pair of UREI 813A loudspeakers that would do the job, but the 813As are massive and fragile with their exposed drivers. They were meant to be mounted high in a mixing room, not to be used in a residential situation with cats, children and klutzy owners like myself.

So I searched around and found a pair of KEF C-75s on Ebay. I liked the sound of my diminutive Q30s and thought a larger KEF model would be an improvement. The KEF C-75 appeared to have everything I needed - high efficiency, a time aligned (or near enough) drive unit (Uni-Q) and a low profile. I put in a bid and won them from a seller with a 100% feedback rating. Well the speaker gods have never looked kindly down on me - when I received the speakers and plugged them in I found that one of the Uni-Q drivers was already blown with a fried voice coil. The C series of yore was never exactly a popular speaker on this side of the pond, so finding a replacement was going to be hard to do. So with great disappointment the C-75s went under the stairs until I could find a suitable Uni-Q driver.

That very next day I stopped in at the Corner Record Shop and sauntered into their used stereo equipment room to take a look at their current speaker offerings. Right away I spotted these tall black tower speakers made by PSB priced at $225. I looked a the back tag and saw they were called 'Stratus Bronze'. After buying a Tyrone Davis LP, I went home and did some googling on the PSBs. Reviews were favorable and they seemed sensitive enough for my needs. These were originally priced at ~$1100, so the asking price of $225 was a screaming bargain. So back I went with my friend Chris and I gave them a quick listen on a vintage receiver to be sure there was nothing obviously wrong with them. No apparent problems so into the Volvo they went for their journey back home.

An interesting thing about PSB, they are a Canadian company and the government has actually funded research so their speakers could be internationally competitive. So lets find out how well a pair of 'big government' speakers do. ;)

The PSB Stratus Bronze is known as a 2 1/2 way system. The tweeter (of course) handles frequencies from 2kHz on up, one of the woofers handles the bass under 500Hz, while the second one just handles the midrange. If you bi-amp, both of the woofers will be handled by one amplifier while the other drives just the tweeter. I would have preferred a bass woofer and midrange woofer/tweeter bi-amp setup.

The physical design is the popular tall but not wide tower. The popularity comes from the small footprint and the wife friendly (make them disappear!) looks. Of course this makes it easy to squeeze in near your TV which is where the majority of speakers end up these days.

I did my listening with a K&K RAKK DAC, 6N6P linestage (or Bride of Zen linestage),my pair of EL156 amplifiers, and various Cardas and Canare cabling.

Setup was easy enough - move my little KEF Q30 speakers out of the way and screw down the speaker cables. I played a little bit with placement and found that I preferred them two feet away from the back wall. Putting them closer to the wall would have increased bass response to the detriment of imaging. Perhaps it is some psychological trick, but speakers put close to the wall seem to image flatly (that is to say with little depth). It may have been (re-)breaking in of the capacitors in the crossovers, but the sound seemed to improve with bi-wiring. Don't ask me why this would make a difference technically, I'm just reporting what I heard.

First impressions were of an extremely clean and extensive treble, a very neutral midrange and a somewhat dry bass response. Overall soundstaging was a little flat with a small loss of body. The speakers never sounded forward and the sound always hung behind them without projecting into the room.

I listened to various audiophile and non-audiophile releases. Richard Hawley's "Coles Corner" has some well record tracks - notably "Darlin' Wait For Me" with its simple instrumentation. With the PSBs the drum kit actually seems to be sitting far behind Richard Hawley's voice. A neat stereo trick that not all speakers can pull off. Two guitars sit left/right in the stereo spread and there seemed to be some loss of definition - like the speakers did not fully resolve the actual presence of the instruments. But still you got a feeling that a whole band was right in front of you, just playing through a bit of a fog. Hawley's distinctive voice however was very clean and powerful as ever.

Earth Wind & Fire - "That's the Way of the World" (Mobile Fidelity) is full of 70s goodness and deep funky bass, but the PSBs 6.5" woofer could only reproduce the top of the bass spectrum. The low bass was rolled off considerably compared to the mighty 15" woofer on the UREI 813s. Of course the 813A takes up 4X the space and weight 5X as much. Well you still can't break the laws of physics - a small woofer can only move so much air. Some of the multi-vocal harmonies also broke down with the PSBs making it harder to hear in this particular mix. I know, I'm expecting a lot out of the PSBs if I'm comparing them to the UREIs which were a studio standard for years.

Bela Fleck - Drive (Mobile Fidelity) is a well recorded bluegrass bit of music. It is multi-miked, giving a rather artificial listening experience. Of course everything about audio reproduction is artificial, but if I was the recording engineer I would have done this a little differently. Anyways the acoustic instruments sound quick with plenty of fast picking going on. A lesser speaker falls apart, making the music become just a blob of noise. Heck, 99% of the speakers on the planet render music like this! Well the PSBs do a competent job of keeping it all together, but with a slight loss of definition. However I can pick out the different instruments and follow their separate line in the music.

I briefly tried some bi-amping, using four monoblock tube amplifiers to drive the speakers. My Dynaco Mark IIIs drove the woofers while the SE EL156s amplifiers just drove the tweeters. This seemed to open up the dynamics a touch but I wasn't too keen running all that vacuum tube power on a daily basis just to listen to music. That's a lot of power and power tube usage.

As you can tell, my praise isn't exactly resounding with the PSB Stratus Bronze speakers. However at this price range, every speaker is going to have faults that are easy to pick up on. Though I mentioned 'definition' problems, I'm comparing the sound to the UREI which was used in mixing rooms across the world. Every engineering choice is about trade-offs, and the designers at PSB did what they could to minimize colorations. And that is perhaps my biggest fault with these speakers - they tend to sound too polite and just a little too reserved for my tastes. This reserved sound seems to be very popular with many audiophiles but I'm not a fan of it myself. Dynamics were never thrilling or expanded like some other (though more expensive) speakers I have heard. Music naturally breaths with changing dynamic peaks and valleys - the PSBs however seemed to minimize these changes. Perhaps this was the fault of my amplifiers - maybe the PSBs require some larger solid state power for me to fully appreciate them. A 4 ohm load for a SE amplifier (even with negative feedback) can be a bit of a difficult load. Perhaps I should have pulled down my McIntosh MC-250 from upstairs and see if that improved anything. I guess this opens me up for a future update.

So if you come across a pair of PSB Stratus Bronze speakers, I would suggest some good low impedance amplification that can handle the 4 ohm load. If you have an extra amplifier to spare, check out bi-amping too. Listen carefully and see if you can live with the aural vision that PSB is offering. I should also note they worked flawlessly at all times and sounded very good for home theater use.

12/15/08 Update: I recently got a Threshold S/500 amplifier that boasts 250WPC into 8 ohms. It also boasts a staggering 500WPC into a 4 ohms load like the PSBs. I hooked up the PSBs and gave them a listen. The extra power and current driving ability helped flesh out the bass a bit more, but I was still disappointed by the lack of low bass. Impact/dynamics were helped out but still seemed a little muted even compared to the KEF C-75 with its 8" woofer. These speakers definitely need some subwoofer help if you plan to listen to rock or action movie soundtracks at decent listening levels.

Midrange and treble remained the same with lower definition than my other speakers. The overall sound was polite, reserved and smooth. If this is the type of sound you are looking for, then go ahead and give the PSB Stratus Bronze speakers a try.

Frequency Range : 40Hz-21kHz +- 3dB, 45Hz-20kHz +/- 1.5dB LF Cutoff -10dB 29Hz,
Impedance: 4 ohms
Power required: 15-200Watts
Tweeter: 1" Aluminum Dome with Ferrofluid tweeter
Woofers: two 6.5" Felt Cone Rubber Surround 1" VC/16oz magnet,
Crossover: 24dB/octave Linkwitz Riley, 500Hz Butterworth
Internal volume: 1.56cu ft
Design Type: Bass Reflex
Size: 9" X 36.75" X 12.75"
Weight: 39lb
Misc: Dual 5-way gold plated binding posts and bi-ampable

from here.


1 comment:

Chris said...

If you still have these, would you pull the xover and look at the high-pass board? There are two ceramic resistors - a 4 ohm and a 30 ohm. Has the 30 ohm been clipped off at one end? I'm trying to troubleshoot mine, and can't find a circuit diagram for them.