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Eminent Technology LFT8B’s reversing woofer polarity

Hi,

I have a pair of the Eminent Technology LFT8B’s and read Dr. Robert E Greene review in the Absolute Sound magazine (2014 I believe) of the speakers where in the review he reversed the polarity of the woofers and said it made a significant improvement. He was going to give the speakers a mediocre review (his words) before doing this and after reversing the woofer polarity he then said they were significantly better and proceeded to give them a rave review. Have any LFT8B owners out there ever tried this? Thank you.

Scot
scothurwitz
ledoux1238
354 posts
 
@bdp24 
Leaving the SA stands is probably the way to go with a bit more mass, as you say, at the bottom. How is the height of the Townshend pods affecting listening on the vertical axis? Do you need to change your chair / sofa height?  I find the ET’s particularly sensitive on the vertical axis. I sit low on a reclining chair while listening. And I find that tilting the ET’s 1.5 cm forward gives me the best soundstage and imaging. Adding the pods will raise the speakers quite a bit. 
decooney
2,358 posts
 
Placement and the amplifier driving the 8 and 16 model ET speakers is key.  I've heard both speakers about ten times with some great amplifiers at a local dealer who's sold them longer than any other shop in the USA  ETs can sound incredible, deep bass, midrange, detail and smooth in the right setup. Can be really fun speakers to listen to.  
bdp24's avatar
bdp24
10,317 posts
 
@ledoux1238: The Townshend Pods raise the height of the LFT-8 about 1.5" above that of the SA stands’ stock spikes. One reason I prefer planars is because of the higher image they create relative to most "box" speakers. I like looking up at the "stage", not down on it (as if from the balcony in a theater).

I sit in a low-back stuffed chair, my ears around 38" off the floor. The panel of the LFT-8 contains a pair of vertically-aligned---one above the other---m-p drivers, almost filling the entire 12" X 48" panel. The single ribbon tweeter which runs alongside those drivers is centered above the middle of the panel and the midrange/bass drivers, and is of course very limited in vertical dispersion. If your ears are below the tweeters radiation pattern, the rear of each speaker can be raised above that of the front, to aim the tweeters output a little downward. A couple of MDF or Baltic Birch blocks will do for testing, a set of BDR discs used permanently if you like (their 2-3/4" diameter is perfect for supporting the bottom of each pod. I use them between the Pods and my carpeted floor).
ledoux1238
354 posts
 
@bdp24 
Thanks for the BDR tip. I am sure I can source locally for something similar. The Townshend pods will be inserted sometime down the line.

There is a question about adding OB subs to the ET’s. I think you run GR Research servo subs and you do not connect to the ET’s woofers. You mentioned somewhere that the ET’s crossovers still engage the woofers even if they are bypassed. Have you tried to disengage the woofers from the crossover?
bdp24's avatar
bdp24
10,317 posts
 

@ledoux1238, the LFT-8b contains two pair of binding posts, one for the panels, one for the bass bins. The speaker comes with a set of jumper wires between the two, to facilitate running the speaker with a single stereo amplifier (the power amp can be connected to either set, to the panel posts makes the most sense). If one wishes to bi-wire or bi-amp, that jumper may be removed. That also allows one to not connect the bass bin at all, which is what you do if using a separate woofer/sub. So the woofer doesn’t see the signal at all, but the power amp still sees all frequencies, including low frequency ones.

One of the benefits of full-on bi-amping is keeping bass frequencies (in the case of the LFT-8b, those at and below around 180Hz) out of the power amplifier, which raises the power available to the panels whilst simultaneously lowering the distortion the amplifier produces (especially advantageous with a tube amp). The LFT-8b instruction literature includes details on how to create passive 1st-order low-pass and high-pass filters (an external x/o for bi-amping), the employment of which provides those full bi-amping benefits.

If the LFT-8b is used without a separate external x/o, while the power amp will see bass frequencies, the m/t panel won't, as the speaker-level x/o is already removing low frequencies from the signal sent to the m/t drivers. It's not as complicated as a first reading of all these details may make it seem!

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