Ancientflatulence Posted June 21, 2015 Posted June 21, 2015 My ML2 References were nearly finished at the time which is why I remember the discussion. Thank God the Limited were so much more expensive otherwise I would have been thinking very, very hard about trying to change over to them which would have been impossible as my References were not, ummm, shall we say, a conventional colour.
ljmac Posted June 22, 2015 Posted June 22, 2015 Yep, according to what Mike told me, the heat conversion factor was the thing, plus potentially superior grounding. However, at the time I ordered my Limiteds (the first pair with external crossovers), Mike was still finishing Assisi's pair, so it was untested. I decided to go with steel as it was tested, has (as Assisi says) a higher Young's modulus, and - most importantly for me - kept the weight manageable. The cost difference sealed my decision. As there haven't been two otherwise identical Limiteds, the copper remains largely untested to this day. Subjective reports from people who've heard several pairs (e.g. Bill) seem to indicate that steel results in better bass and a more liquid sound, but copper provides better treble and detail resolution. This is very anecdotal however, and I certainly have no complaints about the treble and detail resolution of my pair (although I did find it a tad laid back out of the box, which cleared up with running in).
davewantsmoore Posted June 22, 2015 Posted June 22, 2015 How are the drivers attached to the baffle? Screwed into the woof? Threaded inserts? T-nuts?
Volunteer sir sanders zingmore Posted June 22, 2015 Volunteer Posted June 22, 2015 At the risk of asking an ignorant question, what is the relevance of grounding for a speaker?
ljmac Posted June 22, 2015 Posted June 22, 2015 At the risk of asking an ignorant question, what is the relevance of grounding for a speaker? From a technical perspective, I have no idea - I think Mike will have to explain that. However, my Limiteds with external crossovers allow you to disconnect the earths, and it certainly makes a difference to the sound. I actually preferred them disconnected out of the box (it made them sound more lively), but after running in, I now prefer them connected (smoother, less strident).
davewantsmoore Posted June 22, 2015 Posted June 22, 2015 At the risk of asking an ignorant question, what is the relevance of grounding for a speaker? At the risk of preempting anything Mike may, or may not say on this ..... Shielding
gainphile Posted June 26, 2015 Posted June 26, 2015 Very cool build process! Just one observation, the tweeters could have been much closer to the woofer? 1
Lenehan Audio Posted June 27, 2015 Posted June 27, 2015 Very cool build process! Just one observation, the tweeters could have been much closer to the woofer? Hi Gainfile. The distance between the woofer and the tweeter can be determined by using the Wavelength at the Xover frequency as a guide ! So if the Xover frequency is going to be say 2000hz one can determine that a distance of 160mm is theoretically feasible . This distance though will always be too long in my experience. It does look like the tweeter is closer in this design because the Morel Supreme tweeter only has a 72mm face plate as opposed to a normal 105mm faceplate. The questions to ask are these. 1. What is the slope of the high pass and low pass filters ? The shallower the slopes the closer the drivers have to be 2. If one determines a certain distance is ok , from where is that certain distance measured from ? The the centres of the diaphragms ? Wrong . It should be measured from the actual acoustic centres of the driver diaphragms . Ok so where is the acoustics bloody centres then ? Ahh Ha , that needs to be determined by particular measurements in concert with the specific shape of the baffle . I have nutted my own way of measuring acoustic centres and the particular distance between the driver diaphragms. Every breath you take here on Earth is a compromise and so is this part of loudspeaker design. Mounting the tweeter as psychically close to a mid woofer as possible is a mistake as the woofer basket resonates like a mongrel and if there's not enough realestate in the middle the tweeter body get rung like a bell and you can't EQ distortion out in a Xover ! You can adjust for it by reducing amplitude in that region but it's always there humming away . The solution is to have the correct distance between the drivers and make sure that the area between the drivers is braced correctly to sink as much of the woofer basket oil can resonance away. Holy Smoke my one typing finger is nearly falling off !!! Sorry Lads Mike Lenehan 4
Lenehan Audio Posted June 27, 2015 Posted June 27, 2015 (edited) At the risk of preempting anything Mike may, or may not say on this ..... Shielding Hi Dave. Mate yes OK !!! Thanks mate , there goes the IP , just kidding ! In fact this is a definite part of both the steel and copper plating in my Loudspeakers.When you have shielding one needs to sink that shielding away and this is why the plates are connected to certain parts of the ground planes of the Xover. This works however in the opposite direction to the usual usage of a faraday cage ! Aka CIA listening post. In this case we are trying to keep stuff out not keep signals in . Tests with the ground planes connected and disconnected is very audible , the improved dynamics speed and noise floor differences are significant . Regards Mike Lenehan Edited June 27, 2015 by Lenehan Audio 1
Lenehan Audio Posted June 27, 2015 Posted June 27, 2015 From a technical perspective, I have no idea - I think Mike will have to explain that. However, my Limiteds with external crossovers allow you to disconnect the earths, and it certainly makes a difference to the sound. I actually preferred them disconnected out of the box (it made them sound more lively), but after running in, I now prefer them connected (smoother, less strident). Hi Lee. With a burnt in speaker disconnecting the ground planes produces a raised noise floor intermingling with the actual signal going into the speaker. Regards Mike
Lenehan Audio Posted June 27, 2015 Posted June 27, 2015 How are the drivers attached to the baffle? Screwed into the woof? Threaded inserts? T-nuts? Just M4 or M5 tapped directly into the HD3 Dave ! The stuff is like very hard and strong. Regards Mike 1
Lenehan Audio Posted June 27, 2015 Posted June 27, 2015 What is the purpose of the copper lining? Hi Zip. Are yes it's the Bells mate the BeLLLLLs ! Basically this is why Bells are made from copper bronze materials ! It has less HF harmonics and rings less at very high frequencies . They sound more harmonious ringing at the lower tones without the higher order ringing of steel. Also copper converts vibration to heat faster so stops the cabinet vibrating in less time than steel. Mechano Thermal transfer means some of the vibration is converted to heat so the energy is used up by thermals rather than mechanical amplitude . Mike
Lenehan Audio Posted June 27, 2015 Posted June 27, 2015 (edited) My head is spinning ........... :huh: I knew you were a spinner Cameron !😠Edited June 27, 2015 by Lenehan Audio
ljmac Posted June 27, 2015 Posted June 27, 2015 Hi Lee. With a burnt in speaker disconnecting the ground planes produces a raised noise floor intermingling with the actual signal going into the speaker. Regards Mike Hi Mike. That's really interesting - as you know I preferred them without the grounds connected when they were new, but after burn-in, I was surprised at how much better they sounded with them connected. Why is it that this only happens after burn-in?
Lenehan Audio Posted June 28, 2015 Posted June 28, 2015 Hi Mike. That's really interesting - as you know I preferred them without the grounds connected when they were new, but after burn-in, I was surprised at how much better they sounded with them connected. Why is it that this only happens after burn-in? Hi Lee. When ML2's are new they are factory run in but only to run the drivers in which take only 50/70 hours . The Xovers take for Flammin ever. In the case of the limited about 800 hours ,mainly because of the large 10awg inductors and giant Duelund Cast capacitors . Ok when new the sound is slightly analytical of maybe wirey is a better word ! Disconnecting the ground planes can allow the raised noise floor to mask a bit of that wiry ness . The resolving power of ML2Limiteds is I believe at the edge of what's possible with moving coil Loudspeaker design. Having said this I think that this resolution can be a bit much until the design is fully settled in . running the ground planes definitely reduces the furr ! If you get my meaning. Regards. Mike Lenehan 1
ljmac Posted September 4, 2015 Posted September 4, 2015 What's happening with these beasties? Really curious to know how they worked out.
bhobba Posted September 4, 2015 Author Posted September 4, 2015 Mike is still working on them in between all the other stuff he has to do. They are progressing. The latest is he is really happy with the bass they are producing. Also a capacitor comparison GTG may be on the cards seeing which is better the Cast or the new Jupiter copper. I have heard the Jupiter in my Leak amp with Rawl99 and Keith Eichmann. Very very impressive and quite possibly what I will be using. When finished there will be a GTG comparing them to my ML2 Limited. Thanks Bill 2
bhobba Posted May 13, 2016 Author Posted May 13, 2016 (edited) Hi All Well finally Mike got both my Limited speakers working as prototypes with temporary crossovers. Mike hadn't even heard both himself. He simply took measurements ensuring they had a flat frequency response and the tweeter had a deep null when anti-phased. When that was done here is what happened. Our jaws dropped - we had never heard such clarity and speed before - even from electrostatics. It was disconcerting. They were just so transparent - easily above the my ML2 limited. It wasn't better in every area - it was a bit thin and slightly cold - but you tended to ignore it because of the jaw dropping speed. I listened to my usual test track - Dianna Krall - Case Of You - no doubt about we were hearing stuff we never heard before. Rawl 99 was there and he knows classical music well so played some of that. Same thing - unbelievable detail and speed - but still a bit thin and cold. Very very encouraging since this was simply a prototype crossover - the real crossover will use much better parts and will be cold welded rather than using alligator clips etc. Anyway Rawl and me were about to go but Mike wanted to put on the ML2 Limited. He went over and noticed one of the alligator clips was not properly connecting. That was corrected. Holey Carp Batman - instant improvement - now not thin and much less cold. This was really something. We listened amazed - speed demon speed - amazing transparency and clarity. I think Mikes wants to use the Magnesium driver on all his future speakers - it really was that good. Ok we put on the ML2 limited - no where near the speed and transparency - but more refined and organic. Rawl said if Mike can get that kind of organic sound with the speed and transparency he will really have something. Mike is working on it and Rawl is optimistic. So stay tuned. I also chatted to Mike about doing the capacitor comparison. The speakers use 8mf capacitors and Mike already has 8mf Cast. I said i am happy to pay for VSF Duelund and Jensen Copper of that value. Mike is going to build the crossover into the speakers dedicated stands and will do it so the capacitor can easily be changed. So stay tuned for a GTG to see exactly what the go is regarding capacators - it should be a great event. Why did it sound so good? In the past Mike hadn't used really high end expensive drivers because cabinet resonances masked their advantages. He had compared drivers, including expensive Scan Speak Revelator etc but found the one he currently uses the best. He had not tried the Magnesium cones because as they have a difficult to tame resonance peak. You normally use a trap but the trouble is they can drift and cause audible problems. Other designers certainly didn't find it easy eg: http://www.northcreekmusic.com/Pegasus/Pegasus.htm Here he will try and stop that by having the crossover as low as possible and re-tune the trap when the speaker is run in. But why the transparency that other speakers that use this driver do not have? I have heard speakers with this driver before - but nothing like this. The cabinet is simply very very dead. Lined with copper and braced with 36mm cast iron rods as well as silicone filled copper rods. It's the deadest cabinet Mike has ever built. It allows the technical advantages of this driver to be heard. If anyone can make it down to Mikes do so - you will likely be amazed like we were. Thanks Bill Edited May 13, 2016 by bhobba 3
ljmac Posted May 30, 2016 Posted May 30, 2016 Very interesting - so exotic drivers do make a difference after all. Hardly surprising, given that everything else does! Still, one must be careful of psycho-acoustis effects - a thin/cold balance accentuates the sense of speed and detail. Maybe once Mike gets it neutrally balanced it won't seem so detailed any more. We shall see. Ideally Mike should also try sticking his usual drivers in this cabinet to eliminate that variable as well.
ljmac Posted May 30, 2016 Posted May 30, 2016 I forgot to ask: did Mike successfully implement the bass reflex ports into the speaker stands? If so I've got to see photos!
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