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May 2010 issue - page 3

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May 2010 issue
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CANADA SPRY

I am from Canada and I have been a faithful reader of your magazine for many years. I like your reviews because they are honest and informative. I saw the LFT8B review in the January 2010 Hi-Fi World and I resonate with your comments. Yes, it is power-hungry but the distortion remains very low until you drive it into the non-linear range. I use a pair of Melody 845 PP 80W Class A monoblocks to drive them. The preamp is from Audio Note.

I spent the last few years making improvements to the LFT8 and I have a little write up I hope I can share with present and future owners of the LFT8.

Several years ago I was at the CES show and I visited the Monarchy Audio room. I was the Canadian Distributor for Monarchy Audio in the nineties. C.C. Poon, the owner of Monarchy Audio, was using his solid state monoblocks to drive a pair of panel speakers. The panel speaker sounded very good. I wrote down the brand of the speaker and moved on. I was using two pairs of Quad Electrostatic speakers in a custom stack frame for close to twenty years before the hassle and the cost of replacing burnt out treble panels forced me to abandon them. Since then I was looking for a reliable replacement.

 

A couple of months later I read in the British magazine Hi-Fi+ that the Eminent Technology LFT 8 speaker was in their opinion the best speaker in CES. I checked my show notes and the speaker in the Monarchy room was the LFT 8. I called up C.C. Poon and asked him to introduce me to Bruce Thigpen the designer of the LFT 8. After a couple of phone conversations I ended up buying a pair.

 

I have a good size dedicated listening room, 16ft X 26ft, with a sloping ceiling. The highest point of the ceiling is 13ft high. Bruce told me the woofer can reach very low but it does not play very loud. He was right... the woofer would bottom out way before the panel. If you go to the LFT forum this is one of the complaints of the speaker.

 

The following year in CES I dragged Bruce out during the lunch break and discussed what to do about the woofer situation. I wanted him to sell me an extra pair of woofers with the enclosure so that I can experiment with it. Bruce has never tried adding another woofer to the LFT and I told him I would try the woofers in parallel and then in series. A few weeks later a pair of woofer plus enclosure arrived. There is only one crossover component, it is the low pass coil in series with the woofer. I first tried the woofers in parallel. This gave increased weight in the bass but again the woofers bottomed out way before the panels.

 

Putting the woofers in series gave excellent results. There was a huge increase in dynamics. My drum CD sounded better than ever. This makes good sense if your amp has a wide output voltage swing and is able to drive the series connected woofer to bottom out before clipping then for the same acoustic output of a single woofer the cones of the series connected woofers only have to move half the distance.

 

With the woofer situation resolved I called up Bruce and asked... What’s next? He said the crossover. Out goes the internal crossover and I moved the mid range panel and the ribbon tweeter to another connection block to be connected to an external crossover. Bruce also gave me a hint that the 470uF non-polar electrolytic capacitor in the mid range crossover has a big effect on the sound. For the next eighteen months on and off we tried many types of caps and smaller bypass caps. The final combinations that won the day were the Unlytic film caps. We used two Unlytic UL30 series 230uF, 500v caps. bypassed by a Unlytic UP36 30uF 600v cap. The soundstage opens up and the mid range is crystal clear now. Unfortunately, these caps are very expensive but I think they are well worth their price.

 

We also discover that the ribbon tweeter caps are very important. Again, after many months of trying and a lot of money on all sorts of caps we settled on using the Mcap 2.2uF silver/oil for the midrange and tweeter drivers. The midrange crossover coil we used a Litz wire coil from Solen. We have not tried other type but we think the copper foil type will also give excellent results. Our next step is to put the crossover in a proper housing...

 

eminent_lft_8a

 

The magnetic planar LFT 8b loudspeaker, very low in distortion but bass can be improved says reader Kit Fung.

 

I have gone to the CES for the last twenty years and recently I started going to the Rocky Mountain Audio Fest in Denver. I spent a lot of time listening to speakers. Many of them are excellent and very expensive. After the show when I get home I turned on my stereo and listen to the modified LFT for a couple of hours, all the urge of buying new speakers are gone. The modified LFT is not the last word in speakers but for the money I have invested in it, this is a steal!

 

My LFT8 was upgraded to LFT8b when the new tweeter was introduced.

Kit Fung

Canada

 

Thanks for your thoughts on the LFT 8b, Kit. They really are a very accurate, open and truthful loudspeaker, quite unlike most and certainly one of the best loudspeakers I have heard. I think you have every reason to be happy with them. NK

 

THE QUADFATHER

While researching and expanding my system the last years I followed all the English magazines I could purchase here. The one that I still follow, is yours. For me it remains the most inquisitive, informative, and critically even handed. The section on old classic equipment is excellent for us “men of some age”.

 

But the letters section is unique among magazines, in the dialogue that you create, and the trouble you all take to give in depth answers and help. So here I am for the first time writing to a magazine...

 

As you will see from the list of my equipment and the photos that I sent you, I could say that I have brought my system to a point where few changes need to be made. But as always there are questions, hence this letter!

 

I would like to update my trusty Quad ESL-63s, with which I use the REL Stadium III. I need your expertise as to whether to go for the replacement with the 2805, or the 2905s. I have of course read your past reviews and your enthusiasm for the larger Quads over the 2805s.

 

My dedicated listening room is 4.20 x 6.60 metres, which I would think is just large enough for the 2905s. The back wall is triple glazed glass with blinds and curtains. But the ceiling is only 2.30m high. So I am concerned that the bass of the larger Quads would be overpowering in this room.

My collection is primarily classical and jazz with thousands of LPs which the Brinkmann two arm LaGrange does more than justice.

 

CD plays a minimal role. In fact, I bought the North Star combo after reading about it in your mag. So what would be your recommendation for the Quad replacement? Do I go for the 2805 and keep the REL, or will the 2905s work even better? Second question is whether in your and David’s opinion there are any wonderful tweaks to improve even further the Marantz Model 9s that are the second set of amps that I, on late evening jazz sessions, use instead of the Rowland Model 6s.

 

The Marantzs are the re-edition version along with the Model 7 preamp that I was lucky to get from a dealer friend. I don’t use the preamp much since the Rowland Coherence II is so far superior.

 

But I have tubed the 9s with NOS Mullard EL34s and they sound wonderful. I assumed that they didn’t have to be matched sets of quads since they are individually adjusted for bias. Although the seller assured me that they were two matched sets. On this point it strikes me how frequently they have to be adjusted.

 

Also, on running them in triode mode the AC balance has to be adjusted quite a bit; I didn’t know that was normal. The cables to the Rowlands are Synergistic and to the Marantz Townsend Isoldas. I must of course admit that it is a killer to go from the classic Rowland 6s of the 1990s with their fantastic tube like sound and phenomenal resolution to the aura of the 1960s in the legendary tubed Marantzes.

 

What a killer not to have both combined. And then listening to one set you see what you are missing that the other has... But who am I to complain, when I already have such perfection to play with back and forth.

John Demos

quad_esl63

Do you keep a Quad ESL-63 with subwoofer and upgrade it, or trade up to a 2905?

 

Hi John - in my opinion you'll just about get away with 2905s in your room. They're in no way 'overpowering' in the bass department, preferring instead to offer very clean but effortless low frequencies. Most perceived 'bass' is in fact box boom from conventional speakers; the Quads sound altogether very different at low frequencies. They're not boomy in any way, and the 2905s simply add more ease to the 2805 recipe, not more 'boomph'. You'll find either of the latest Quads a step change over the ESL63s. I've heard some superb '63s, but they need to be heavily tweaked; the stock ones, especially ones that haven't been serviced by now, will sound altogether far more loose and veiled compared to either the 2805 or 2905. Finally, I'd recommend trying a pair of Townshend Audio Supertweeters; these are brilliant partners for the Quads. I actually use mine 'side firing' (stage left and stage right) with Quad ESL989s, and they snap the midband into even better focus and add welcome air to the treble. DP

 

Having lived with ESL-63s and heard 2905s many times, you might be surprised to know I am unsure what to say! In good form, the ESL-63 is superb, if a little laid back in the treble. The 2905 is altogether more impressive in its scale. The problem I have is that with loudspeakers firing down the room and you close to the end wall on a settee, your room looks lumpy down at 54Hz when analysed using Cara (room acoustic analysis). However, it is quite smooth down to 40Hz if you place the speakers to fire across the room, as I did with my ESL-63s, also in a 4.2m wide room.

 

I do not entirely trust Cara but it usually gets the basic low frequency modal properties of a room right and suggests the 2905s may well sound a bit bass heavy. You would have to get a pair for demo and see whether this was the case. Large settees absorb energy and damp a room well I find, taming such modal effects. I use a large three seater, a two seater and an armchair and they make a huge difference to bass quality, in a room similar to yours.

 

The advantage of a subwoofer with ESL-63s is that you can adjust bass level to best suit both your room and your taste. An alternative is then to have the ESL-63s refurbished by Quad Musikwiedergabe (see www.quad-musik.de). I assume you have the later protection diodes fitted, and not the earlier self powered compressor that muddled the sound. There's much to check with Quads. And of course, if you do trade up to 2905s, be aware that ESL-63s in good condition are sought after and will fetch a good price.


On the amplifier front, do try and audition Quad II-eighties; designed by Tim De Paravicini in true Quad tradition, they are wonderful.

NK



 
Comments (1)
Speaker matching with Lumley ST70
1Saturday, 02 July 2011 09:06
Mike Ford
The Output transformers on The Lumley ST70 have 4 ohm taps but these are not wired to the output terminals as standard. A competent technician should be able to alter the connections to 4 ohms.

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