Eminent Technology LFT8B’s reversing woofer polarity

@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).

@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 
1. Can I simplify use two separate amps, one connected to m/t panels and one connected to the woofers, without a cross-over? Do I need some form of volume control for output mismatch?
 

2. From reading the manual, I need two x/o in passive application, one 180hz high pass and one 180hz low pass. 
a. Where can one find ready made high and low pass x/o modules?
b. Where to I connect these to?
c. Would I need additional volume dial to match output?

@ledoux1238:

1: You sure can. However, if the two amps don’t provide the same gain (fairly likely), you WILL need a means of adjusting the volume of the higher gain one. Some power amps include a volume control, but these days that’s rare. A simple outboard volume "pot" at the input of the power amp will work, but will of course necessitate an extra inter-connect.

By the way, if you use two identical amps, you can bi-amp either horizontally (one stereo amp for the panels, one for the woofers) or vertically (one stereo amp for each complete loudspeaker).

2: Exactly correct.

a: This subject has been discussed in detail many times before on Audiogon, so do a subject search; there are lots of products to choose from. I have the nice little x/o Nelson Pass offered in the First Watt B4, but it is no longer offered factory-assembled (kit only now), though it is more x/o than you need for this application (plus it retailed for $1500, perhaps more than you want to spend). There are LOTS of self-contained volume pots (even from ebay vendors), one from HSU (the maker of subs) for under $100. Cheap volume pots are notorious for channel imbalance, so get a good one! When he was alive, Roger Modjeski was offering a "Volume Pot In A Box" pre-amp (he was a proponent of passive pre-amping). Contact Music Reference to see if there are any left in stock.

However, the best way to do the filtering (possible because that needed is the simplest of all types) is a passive, 1st-order (6dB/octave). All that requires is one cap and one resistor per channel, which can easily be soldered onto the input jacks on the power amps, inside the amps. Why is that ’best"? No extra inter-connect required, no extra breaks in the signal path. Less is more! (that goes for you too, musicians ;-)

If you have a good tech in your area, having him do the work won’t cost you much. I had Tom Carione at Brooks Berdan Ltd. in SoCal install the exact filter you need in my Bedini 25/25. I had him replace the stock binding posts with Cardas at the same time.

b: already answered.

c: ditto.


I hope this doesn’t sound too daunting. Used as delivered from the factory, the LFT-8b already sounds great (have you read the review by Robert Greene in TAS, or the reviews in UK mags?) . I would listen to the speaker stock, see if you like it enough to take it to another level. Be sure to get the dedicated stand Sound Anchor makes for the LFT-8b. If you’re familiar with that stands they make for the Vandersteen speakers, you’ll know what they look like. Eminent Technology stocks and sells them.