Sunday, May 13, 2012

Full range speaker competition

Our full range loudspeaker competition (May 2012) proved to be very interesting. After all of our discussions about 'helper' speakers to assist at the bass or treble ends, none of the five entries used them. Unfortunately we were not able to use the small meeting room at the library and we had to be in the large (38' x 38') room. I thought there might be problems with small full range speakers generating enough volume, but all were able to play loudly enough.

We did find an interesting room node however. If you stood at one spot, the image of an instrument was between the speakers. Move six inches to the right and the instrument moved into a corner of the room, twenty feet away.



First up were David's Fountek FR88 EX speakers in a half litre cabinet. These were not really designed to be run full range and had a capacitor designed to roll off below 200 hz to protect the small speakers.



Next were Don's Tangband W5-1880 speakers in a 4 litre aperiodic box. Don has wood working skills that I can only begin to dream about.



Steve used Mark Audio Alpair 7s in his MLTL speakers. These were approximately 5 feet tall and were made from 1x8 pine cut to the appropriate lengths. Steve used Martin King's spreadsheets to calculate the dimensions. It was nice looking pine.


Ray used the less expensive Mark Audio CHR-70 Version 3 speakers in what he calls an H frame horn. There is a write up on the construction of these concoctions here.



Our final entry was John's simple open baffles using the GRS 8FR-8 speakers. The cost for both speakers was under $30.


We used David's 813 amp which we also used in the Russian line stage competition last year. It easily drove all the speakers to loud enough volumes. In fact we were asked to turn down the volume by the library staff at one stage.

The emphatic winner and liked by all was Steve's MLTLs. They did everything well. The smaller cabinet speakers did really well on the female voice tracks but suffered from the expected lack of bass on the more complicated tracks. Both sets of speakers were designed to be used with subwoofers and I reckon they would sound very good with the extra bass. By comparison, the MLTLs really provided the foundation that some of the music required though some comments noted that some bass notes were a little boomy. One of our test tracks (some incidental music to William Walton's Henry V - Meridian CDE 84349) sounded pretty awful on the small speakers but much better on the larger speakers. It just shows that not all of the test tracks should be of audiophile quality. 

The horns produced mixed reactions. The treble seemed rolled off compared to the other speakers which suited some tracks, but not others. Some liked the mid range but others were not so keen. The bass is definitely there and is probably the best part of the speaker. It's not boomy. I've been looking at the scoring sheets and somebody described the imaging as 'big'. I would agree with that description and this really helped the orchestral music. I'm biased of course, but I think that the difficult Walton track sounded best on these horns. After listening to them for a few weeks now at home where my seat is just 8 feet from the front of the horns, I would say there is a sense of being in a cave with them when you sit directly in front of them. In my house they sound better when I am not in my usual listening position, but off to one side. To me they sounded much better in the larger room where I could sit well away from them. If I were to experiment more with the design in the future, I would add an upward facing tweeter to provide a more airy top end.

We auditioned the open baffle speakers after we had been asked to turn the volume down so they suffered a little compared to the other speakers. It's a very inexpensive driver and does well in this application with more bass than I expected. However, John was the first to admit that his Visiton B200 speakers sound much better in the same baffle, but their price was above our $200 limit. The GRS mid range did not sound as clear as the other speakers.


Both David and I have built some sand amps as a change of pace. David built a Nelson Pass F5 and I built a Fetzilla which we tried out later in the day after the competition was over. You can see it on the right hand chair. Perhaps we will listen more to these amps at our October meet. My wife and I inherited a cat and I don't feel comfortable having it walk around my tube amps. 


The horns had to be disassembled and we tried an interesting experiment just before we left. Here is Steve holding the horn in front of his MLTL. Some else did the same on the other speaker. We would listen to some music and at the same moment, the horns would be removed so that we could hear the difference, which was dramatic. We all immediately noticed the expected drop in volume. What I did not expect was the sudden collapse in the sound stage and the loss in richness of the midrange. Somebody had commented after the test of the H frame horns that compared to the other speakers, it seemed like the 'Loudness' button was on. I may have to experiment more with these monsters in the future, but since my wife has been more than patient allowing these monsters into our house, the cones were thrown into the dumpster. Nobody wanted to take them home with them. I did keep the drivers however and I plan to use them in a pair of frugel horns.

Our next meet will probably be in the second half of October. We've started to think about our competition for next year and it will probably be an amplifier again. We are thinking that it should be a spud amp (one tube per channel) and the tube needs to have a compactron base.





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