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rickmcinnis

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  1. Attached is a photograph of the right channel - the reticulated foam is two inches in depth not three inches. A reason to consider using two equalizers - of course I would recommend the xilica that I bought upon the recommendation of Chris A: (seeing Danley used them made it even more an obvious choice) When ganged together and the mixer set for one channel for the Celestion and the other for the Crites you have many more opportunities to make the response flatter but one thing I discovered is that one can completey remove the spike, that occurs in my case around 1200 Hz, using the graphic EQ. Starting at 20 KHz and working your way down - -30 dB all the way down to about 3.15kHz. - I am writing from memory - you make make it go away entirely without as much effect on the top end response of the Crites. It is almost like magic. Of course, there is some loss and that is useful just not as much as when I used a PEQ set at the center frequency of the spike plus you get rid of all extraneous information above there. Since the subs share this channel is assists with those, also. I intend to post a screenshot of the response tomorrow. You will see the spike is not minimized it is removed. Same thing is useful for the tweeter in removing low frequencies. One does have to tailor these, of course. It would have taken four PEQs to do what you can with these and thus are able to save those for more important tasks. There is something about the presentation of a system that is dual mono. So for the rabid and determined I think there is no question one should get a xilica for each channel and gang the inputs. Picture is of a speaker and house still being finalized. I have had those ROOM TUNES for decades and they make a big difference in front of those windows. Michael Green was a very interesting fellow. Does anyone know if he is still involved in audio? The pieces of cloth seen hanging down between the cabinet and the foam is a thick wool damask - what I had to use at the time. The wool alone made a nice improvement in the sound and the two together better still. The intention is for all of this to look more "all of a piece" one of these days. You know what is said about good intentions ...
  2. Spending lots of time trying different schemes of EQ with the system. AND yes, I am using the K402s - I continue to call them 401s for some idiotic reason, thanks for the correction, Chris A. My last post about using the high shelf filter has been superseded by using 10 kHz with no EQ as my reference point. I figure with this I am removing all of the acoustic transformation and making the speaker essentially a WAVEGUIDE - I am using about 6 dB of boost - 20 kHz - Q a bit over 1.0.. I have found those xilica graphic EQ filters to be useful. This is in conjunction with ganging the two channels of the 2040 so that one input channel is only for the Celestions and the other for the woofers and subwoofers. Being able to adjust both Crites and RYTHMIKs with the input filters is very handy. I do miss being able to do the same thing between Crites and Celestion but it just takes more work to get the crossover region right. This allows smaller (in cut or boost) filters all around - I am throwing away almost 20 dB of gain at 1kHz and that can result in dips that require even more filters. I have found using all of these together allows a flatter response without too much of the "arguments" I try to avoid. On the woofers using the graphic filters one can do a really thorough job of removing unwanted output from the woofers and not adversely affect the response at the crossover point which for me is nominally 500 Hz. I start at -30 dB at 20 kHz, 16 kHz, 10 kHz and 8 kHz - I then less the cut as I proceed down the range. !.25kHz is a big cut since that is where the big peak exists. I find if I try to go too low with CELESTIONS, just as Chris A warned, things get dicey. The distortion, as measured by REW, is MUCH greater at the frequencies I am trying to squeeze out of the CELESTIONs than with the Crites woofers - so the key is to preserve the response with the woofers and make use of their lowered measured distortion. With the woofers I am throwing away almost as much level. Again I have found the most pleasing sound is with the reference level being at 100 Hz with the woofers. A nice smooth downward slope from 20 Hz to 20kHz makes for good sound which I feel sure is the case for everyone here,. So the shelving filtrs are a dead end but the graphic filters are a godsend. Do not be afraid of them. It does take some time to get used to how they interreact with each other but one can see, before the advent of PEQ these things could do a good job. As long as the job is for small changes. I use the PEQ for the big filters and then use as much of the graphic filters as can be utilized. Sometimes one simply has no choice but to use the PEQ filters, as if that is a bad thing! Even with a ten watts amplifier I do not hear a loss in dynamics - if anything it is otherwise - gets plenty loud for me and that is 100 dB for really raucous recordings (not steady of course). Any louder than that and my room is distorting more than the speakers. I continue to be amazed at how BEAUTIFUL these things sound - that is the system of K402 and CELESTION with the Crites woofers. I still must say there is no comparison to what is possible with the addition of two RYTHMIK woofers per channel and trying to let the speakers play as two ways. No comparison in distortion level and dynamics. If you EQ the MEH to play as a two way it is just not anywhere near as good. This could well be because of my room size and dimensions. Even though the things measure fairly flat in the mid bass at one to two meters they do not sound that way at the chair another couple of meters away. there is a big dip around 115 hz. The effortless bass from four of the RYTHMIKs is something to hear. The bass simply appears and then dies away. No thump - no LISTEN TO THAT BASS effect. Mr. Geddes is right: multiple woofers scattered about the room is better. I have found a good compromise with getting the MEH and the RYTHMIKs to work together in this range. The RYTHMIKs measure extremely low distortion at 125 hx - of course these are REW numbers and I am not sure how accurate they are - I use them relatively. The RYTHMIKs and the MEH are sharing the load up to about 130 Hz. The reticulated foam surround on the K402 is simply a three inches sheet of foam with a hole cut out that is smaller than the mouth - about six inches in width and height, I see no effect on the woofers response and and a slight smoothing of the compression driver. One hears much more than one sees with this addition. II cannot remember the outside dimensions of the sheet. I will measure it. Same with the scrim of long fiber wool in front of the Celestion. A slight loss at 20 kHz but an actual rise in response around 8 kHz. Using two sided tape to hold it close to the front of the Celestion. It is immediately noticeable as a reduction in something! Far more relaxing. I tried it both ways over and over again and it is always an improvement when in place. Looks funny but then how can one be a serious audiophile kook without that! I will take some photos. Another thing I have found to be useful - a 2 x 4 foot sheet of rock wool on top of each speaker - not night and day but a refinement. There is so much goodness in this arrangement with these drivers. One can sit back and be astonished that such sound is even possible in the home. Two channel audio has much to offer. One last thing - with these speakers correct polarity has never been so easily heard. Even though there are times when I think it is good but I figure I should switch it just to be sure only to be very pleasantly surprised it was not and there is this improvement in spaciousness and image along with the all important dynamics. Using the two xilicas as my control center makes polarity change easy even though with the two input channels ganged and using one for each channel I have to click four buttons and access each one for the respective channel. For some a pain in the rear but I think the trouble is worth it. I wonder with multi channel systems if correct polarity is not quite as noticeable? I will never know. I figure I am much too lazy for more than two channels! As usual I write long letters. Take care,
  3. Interesting to see you have given this driver a try. It was my intention to stay away but I will give it another try. For the upper frequencies boost this is a good place to use the HI SHELF option on the xilica. Use a very high Q setting around 7000 Hz. Boost will be dependent upon your setup. I would say exactly what it is but i am at work. You will gain a bit more phase change but also gain a smoother response. I go with Geddes dictum of frequency response is the most important of all parameters. I had noticed (using the RTA) that while listening to music there was very little output at the high frequencies so why not boost it up there? I have boosted as high as the xilica will allow and at home listening levels I never heard any bad effects. This was when i was trying to retain the sensitivity in the lower regions. Now I am splitting the difference between the low and high to keep my filters in balance - too much boost or cut affects other parts of the response more than we want. I am not sure if amplifier quality has a bearing here asking for this boost at these frequencies. I have not tried any amplifiers other than the ones I have. I have found the MEH sounds best when you throw away most of the acoustic transformation. Luckily even with low powered amplifiers the things get plenty loud. I think it is a bit of a misnomer to consider the K401 MEH a horn loudspeaker in the classical sense - at its best we are using it as a waveguide. I have come to conceive that most of what most people object to in a horn loudspeaker is the sound of the acoustic transformation, The most notable exception is Romy Besnow who seems to thrive on it but then he is using his horns in very limited frequency ranges so the acoustic transformation is more equal between the various horns whereas with our systems we are blending the two modes and I suspect this discontinuity is what most people identify as "horn sound". No question in my mind the CELESTION is the best compression driver I have ever heard. I never got a chance to try the 4002 which is said to be greatly superior to the 4001s I did use for few years. The 4001 is said to only work with its companion horn. Using the Edgar round horn it sounded pretty bad - but the reputation of the thing kept me listening to it long after my ear/brain said REPLACE THEM. Of course, everyone knows this now. My system has been completed for a few months now and I still keep tweaking the EQ - funny thing is - no matter what I do the intrinsic nature of the loudspeaker is always there and the intrinsic nature is very fine. There is no doubt when one finds something that works better but this is not hyper critical. One could easily come up with a decent sounding setup without much trouble. But of course, with a fascinating puzzle like the MEH and xilica the desire to try to get it a little better every day is impossible to resist, getting really close though. No question the speakers are dynamic beyond my expectations. Drums sound more like drums than I have ever heard - even at reasonable volume, there is no need for them to be LOUD to hear something that sounds like a tom or a rimshot. - the center image is rock solid and the space between center to the sides are well defined - the loudspeaker disappears. The tonality is simply realistic. Massed strings sound very refined. Vocals can be eerie in their realism. Blah, blah, blah I had hoped these speakers would be better than my previous setups - I knew they would be better and I knew they would take up much less space but I was and remain extremely happy with how much better they are. I cannot imagine anything I could afford that could come close to what I am hearing. I have found that placing a two inches sheet of 20 ppi reticulated foam with a cut out for the opening - but a bit smaller than the horn opening makes for a greatly improved sound. This seems to be well documented as something that improves any horn.. In my case it was instantly apparent. One would think there would be a loss somewhere in the response but in actuality dips in response in the 5 to 7 kHz region were mitigated. Another thing to try is a very stretched out bit of long fiber wool right at the CD opening. Visually transparent - I used two sided tape.to keep it in place. Makes a minimal change in measured response at 18 to 20 kHz but the the sound becomes much more refined. I think both of these things are affecting the horn far more than the driver. No question the 401K MEH is a great loudspeaker, a great stereo loudspeaker and the Celestion driver is an important part of the whole in my experience.
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