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The criteria for loudspeaker choices.

 

I’m signed up for PS Audio promotional emails, and the one that arrived today announces the introduction of the newest, smallest model in their Aspen line of loudspeakers, the FR5. I read through all of the details on the speaker, and one statement made instantly brought to mind a question. Read on if you’re interested.

 

In the section labeled Technology, PS Audio makes this statement:

"We started with our planar magnetic tweeter. Moving air at high frequencies without coloration or distortion is a daunting task. On the FR5 we chose to go with a technology that has the speed of an electrostat with the dynamics of a cone. Planar Magnetics. This ultra-low distortion driver is driven from front and rear magnetic structures that offer inherent linearity through symmetrical "push-pull" neodymium motor structures and directly driven ultra-low mass diaphragms with none of the cone or dome breakup, inductance modulation, or hysteresis distortion that plagues traditional drivers."

Amen, brother! Other information provided is that the FR is a 2-way, with a 6.5" woofer, a Linkwitz-Riley 6th order acoustic crossover frequency at 1750Hz, and a rear-mounted 6 x 9 passive radiator. And that PS Audio makes the crossover using "Custom film capacitors and premium air-core inductors." (hallelujah!) Sensitivity is 83.5 dB, and the price for a pair is $3499 plus shipping.

 

Okay, all that is nice to hear. But what if there were a loudspeaker that uses a Planar Magnetic driver (like that of PS Audio, with a symmetrical push-pull motor structure and directly driven ultra-low mass diaphragm) for not just high frequencies, but the entire range from 180Hz all the way up to 10kHz, with another smaller P-M for frequencies above 10k and an 8" dynamic woofer for frequencies 180Hz and below? And has the same sensitivity (84 dB)? And a lower price ($3200, shipping in the U.S.A. included)?

Well, you would compare the two, and see which produces the sound you like most, right? Well yeah, but if PS Audio’s opinion of Planar Magnetic drivers is well-deserved and earned, why WOULDN’T you want one to reproduce the frequencies below the FR5’s crossover frequency of 1750Hz? There happens to exist just such a loudspeaker, the Eminent Technology LFT-8b. Reviewed by Robert Greene in TAS, and Steve Guttenberg on YouTube.

 

So if the PS Audio FR5 piques your interest, you may want to audition the ET LFT-8b as well. By the way those of you contemplating the purchase of the similarly-price Magnepan MG1,7i: the 1.7i has a single-ended motor structure (magnets on only one side of the diaphragm), seriously compromising it’s sound quality potential. Would you even consider a dynamic driver ("cone") that was single-ended?! And, the 1.7i has a nominal impedance of 4 ohms, but dips even lower at some frequencies, making a high current amp mandatory. The LFT-8 is an 8 ohm load, the Planar Magnetic panel itself 11 ohms (two pair of binding posts are provided, making bi-amping easy).

As a long-time Quad ESL owner, I consider the LFT-8 a Godsend. The transparency and ultra-low coloration of an electrostat, without the maximum SPL limitations of the Quad. Great for the Baroque period Classical and Bluegrass I love, but also the AC/DC I sometimes crave. smiley

 

128x128bdp24
tcatch
36 posts
 

Website says the speakers are eligible for trade-ins up to $875.

terry9
2,354 posts
 

Note that the Magnepan DWM woofer is also a push-pull design and it is flat right into the treble. It is an absolute wonder with my Quads - especially with a decent mounting platform - the one supplied is more stylish than functional.

immatthewj
2,208 posts
 

From what little I know about speaker specifications, and this is what I have learned here, 83.5 is a very low sensitivity and on paper would suggest a hard load to drive(?) but on the other hand an impedance that only dips to 5.6 ohms is extremely good, and since they are suggesting 50 to 150 wpc, the stable impedance must be what makes up for the low efficiency?

bdp24's avatar
bdp24 OP
9,885 posts
 

 

The LFT-8b makes bi-amping a simple proposition, and allows a tube amp to be used on the Planar Magnetic drivers/panels (tubes love an 11 ohm load), and a solid state amp on the sealed dynamic woofer. Splitting the signal at 180Hz eliminates the need for a high current ss power amp. In contrast, the MG1.7i---having a single pair of speaker cable connectors, as well as wiring the various P-M drivers in series, not parallel---needs internal surgery to be bi-amped. The combination of a 4 ohm (and lower) load with an 83.5 dB sensitivity makes a high current amp mandatory with the 1.7i, which is not the case with the LFT-8b.

But back to the PS Audio FR5. I have no doubt it is a fine sounding loudspeaker, maybe even great. And a good choice for a small room. The point I want to draw to everyone’s attention is that if the case PSA makes for the Planar Magnetic driver is as strong as they obviously believe, the LFT-8b uses that technology all the way down to 180Hz, the FR5 only down to 1750Hz. That’s a drastic difference. A whole lot of the sound of music is found in the 180Hz to 1750Hz range.

But then the FR5 is a "box" speaker, the LFT-8 a dipole planar. Not everyone likes, wants, or can accommodate the latter. For those people the FR5 may be a welcome offering. I find a mini-monitor, especially one with a price tag of $3499 plus shipping---of little interest.

 

 

audioman58's avatar
audioman58
4,202 posts
 

For their price decent but components are of lower quality .

for example low grade brass connectors to start  vs a copper WBT 

3 x less conductivity then Copper = more resistance noise to start,

the the critical Xover ,Very  low quality parts .I have worked with many people in over 20 years upgrading Xovers even in much more expensive loudspeakers .

these speakers ,maggi worst connectors Ever and frames I owned 3 flex like a sail,

ps audio ,and Emminant tech. Drivers all made in China . 
which I am no far .as a ex Audio dealer speakers including packaging 4-1 ratio 

is the norm a $4k speakers $1k into the build ,you get what you pay for , better buying something. Much better used  ,the Xover is for sure a good place to start 

if you did buy them  and wanted a very good upgrade. For maybe. $1k in parts 

look inside you will see most likely all yellow no name China capacitors ,and resistors , on many $10 k speakers Solen which are like a 7 out of15 on the quality scale , go to Humble homemade hifi capacitor test

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