moray james Posted November 21, 2012 Share Posted November 21, 2012 would be interested to know what members here have done with and to their compression drivers. Thanks and best regards Moray James. Quote Link to comment Share on other sites More sharing options...
Horatio Posted November 24, 2012 Share Posted November 24, 2012 Modding compression drivers is a pretty touchy thing. On good ones (pro sound, large format), the clearances are pretty tight and the machine work also quite exacting. The only thing I've seen done is the introduction of ferrofluid in the coil gap, ostensibly to improve power handling, and can also be claimed to smooth response. Speakerlab did this on their later compression drivers for their Khorn knockoff. The driver was based on the EV 1824, if I am recalling correctly. I had written to them around 1980-81 about this alteration, and they sent me the frequency response curves for the non-fluidized driver and one with fluid. I think these were on their K400 knockoff midrange horn (H350, a model number like this, anyway). The curves did reveal a somewhat smoother response. The fuuid they used was called Magnar. I suppose you might be able to somehow introduce a different phase plug....other than that, it gets pretty tough, pretty fast, I think. The concept also presumes that the manufacturer somehow missed key factors during development, and I have rather strong doubts that companies like JBL, Altec, EV and the like did this. I can see more likely changes that address manufacturing shortcuts or cost/value engineering compromises. But this is less likely to be the case in the high line large format drivers. That's speculative, of course. -M Quote Link to comment Share on other sites More sharing options...
seti Posted November 24, 2012 Share Posted November 24, 2012 The only thing I've seen is coverting to Field Coil. Quote Link to comment Share on other sites More sharing options...
moray james Posted November 24, 2012 Author Share Posted November 24, 2012 Horatio: thank you for your response. I have found that ferro fluid is a mixed bag and results are not always what the appear to be. Response curves can show improvements with fluid installed but when temperature levels are elevated the benefits melt away. Finding the correct fluid is also difficult. I have had golden eared listeners tell me that even with well chosen fluid application that some drivers do not sound as good with as without. So in the end magnetic fluids are something I generally avoid. The substantial benefits of power handling are usually somethng which do not need to be taken advantage of with compression drivers in most home settings. Phase plugs could be changed but I did not want to get into complex and expensive machine shop time even though my brother is a mould maker by trade. I think it far less expensive to look for a different driver. I have seen a number of products which over the years have evolved such things as phase plugs. So it would be easier to go to the used market and purchase some to try. I tend to agree with you that quality design companies know how to engineer and usually get things right though there are exceptions where older designs continue to outsine newer "better" products. for the most part newer designs are improved. All companies do have a bottom line and they are all looking to save a buck or even a few cents where they can and the power of the accounting dept. has destroyed may a fine product. I agree with you that it will be by looking for and addressing small shortcut and cost saving engineering compromises that some improvements may be realized. I would also expect that your are correct in expecting that the larger format and certainly top of the line prooducts to have far fewer such compromises as these are generally all out assaults in terms of performance and quality. I have been looking recently at possible improvements through vibration damping of compinent pieces and of acoustical damping inside caveties like beneath the diaphragm. I have had very good results using dynamat on driver parts like the back plate the pole piece and other parts of the driver where wall thickness is limited and where less rigid materials have been uses to save both weight and cost. I have also used acoustical felt (SAE rated F-11) to damp the cavity both in the pole piece if there is one and the under side of the diaphragm or cavity behind the diaphragm depending upon which style of driver is being modified. I have also looked at possibel methods to laminarize air flow. For example the withch's hat used in the Klipsch mid driver where I have installed narrow dividers between the exit ports at the base of the hat. The dividers are perhaps 1/16 " or a little wider and they extent up about 5/8's of an inch forming channels to direct air flow up and into the throat of the horn. I will say that this particular modification is not a big one but I do prefer the sound with vs without and I think that with such types of modifications you are looking for the accumulated impact rather than the ulrimate impact of each and every modification. Some will be more effective than others but they all add up. So that is where I am at right now looking at mechanical and acoustical resonances. Driver diaphragm material is a well known area of research and I have considerred experimenting with aquaplast as well as other possible materials for stiffening diaphragms such as structrual adhesives. I consider the improvements which I have made so far as substantial which I think would surprise most listeners who know the drivers I am working on. I hope that the fact that others here now know that someone is interested in and working on such things will peak their interest. I know that there is a knowledge base here which I think is impressive. If some of the other menbers can find a little time in their days to consider these issues and ideas then I imagine that some truly excellent results will arise. Thanks again Horatio for your input it is very much appreciated. Best regards Moray James. PS: can now add to the list of modifications done. Replace the paper spacers under the diaphragm butterfly with lead sheet rolled to the same thickness as the paper spacers. Very nice touch. Quote Link to comment Share on other sites More sharing options...
moray james Posted November 24, 2012 Author Share Posted November 24, 2012 Seti: designing and building field coils is a pursuit where a fella needs axcess to a good machine shop and who has a day job with a good income. Cogent comes to mind. Great stuff from those guys. Thanks and best regards Moray James. Quote Link to comment Share on other sites More sharing options...
David Pritchard Posted November 24, 2012 Share Posted November 24, 2012 Moray: I have found a significant change in sound when the Titanium diaphragm is either cryogenically treated (I used Cryogenics International, Scottsdale, Arizonia) or Quantum Tunneled by Synergistic Research, Irvine, California. Cryo gives a darker more accurate with less metal sound than stock. Quantum Tunneling seems to give a more open and detailed sound than stock. I have even Cryo'ed and then Quantum Tunneled a pair of Titanium diaphragms. I think you would find these experiments worth trying. David Pritchard Quote Link to comment Share on other sites More sharing options...
moray james Posted November 24, 2012 Author Share Posted November 24, 2012 Thank you David: I have been aware of cryo treatment since the late 1980's and was freezing things not long after that. I do not have any experience with the QT process so I will have to look into that. I have found that some of the things that can be done have a subtle impact yet the affect of that subtle change can be anything but subtle. Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
David Pritchard Posted November 25, 2012 Share Posted November 25, 2012 Another interesting area to explore is having the circuit breakers (that feed the stereo system) Quantum Tunneled. It made an immediate improvement on my dedicated headphone system. I have not Cryo'ed any circiut breakers. My house uses the Seimens brand. I certainly am enjoying the Klipsch Titanium midrange diaphrams you suggested in my KLF-20's. David Pritchard Quote Link to comment Share on other sites More sharing options...
Fish Posted November 25, 2012 Share Posted November 25, 2012 I bough some klf20 high freq horns, the whole assembly.They have titanium diaphrams and I was all ready to just change out and try em'(since moray is fond of em')Sadly they did not work, I don't know why.The horn backside itself was totally wrapped in rope putty, actually a pretty nice job at that.Maybe someday I'll figure it out and try em', or maybe send em' to Bob? Quote Link to comment Share on other sites More sharing options...
moray james Posted November 25, 2012 Author Share Posted November 25, 2012 Check the VC with a meter> I have had one Klipsch Ti tweeter diaphragm go open for no reason, while all of Bob's have been fine.Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
moray james Posted November 25, 2012 Author Share Posted November 25, 2012 A simple physical fix that you can play with on your KLF20 mid horns is to add a diffraction ball. I installed a 40 mm dia ping pong ball which is the official size into the throat of the horn. The ball is positioned with some sticky tape and a little string. I have the ball equally spaced beterrn the side walls so that there is about enough room to insert your index finger on either side at the same time. The ball is small enough for the upper range of frequencies to diffract around it and get out of the throat into the horn while at the same time the ball is large enough and deep enough into the throat to block most of the signal reflections which are trying to get back into the throat. This works very well and sounds excellent. I have done a similar mod to the K79 tweeter wir a slightly smaller diametre 38mm ball. Stage image and dispersion are all excellent with smoother sound and much better focus. I hope that this is of interest.Best regards Moray James. PS: inspecting your horn for manufacturing defects is also important. Look for flashing or extended edges which you can trim off and file smooth. In horns like the K700/K701 look for non round throat opening in the K700 and in the K701 look for ripples and discontinuences at the actual throat of the horn. You will need to get your finger inside to check as you cannot always easily see them and sometimes you will find potholes inside the throat. I have found the same problems with the mid horn used in the Quartet, Forte ll and Chorus ll. Fill file and sand smooth. The throat of you horn should be perfect in shape and should have no surface irregularities. Throat geometry is the most important part of the horn. Driver gaskets should present a smooth flat transition between parts, if you have to trim them with an Exacto knife. PPS: David if you want to discuss this further send me a PM. Quote Link to comment Share on other sites More sharing options...
Don Richard Posted November 25, 2012 Share Posted November 25, 2012 Another interesting area to explore is having the circuit breakers (that feed the stereo system) Quantum Tunneled. It made an immediate improvement on my dedicated headphone system. I have not Cryo'ed any circiut breakers. My house uses the Seimens brand. Sounds more like Quantum BS to me. But if spending money on this sort of thing makes you happy, have at it. I prefer to throw my money away on things that might have some ROI, like the $425 million Powerball drawing Wednesday. You have about the same chance of audibly improving circuit breakers with that process as hitting the lottery. Quote Link to comment Share on other sites More sharing options...
David Pritchard Posted November 25, 2012 Share Posted November 25, 2012 I have had my 15 amp circuit breaker (that supplies power to the audio system) Quantum Tunneled and the effect is audible immediately and is not subtle. Government lotteries have the worst payout of any form of legal gambling. That is why the government has made them legal. Quote Link to comment Share on other sites More sharing options...
David Pritchard Posted November 25, 2012 Share Posted November 25, 2012 Moray: I look forward to trying the horn throat diffraction balls. 40mm for the midrange and 38mm for the tweeter- correct? David Pritchard Quote Link to comment Share on other sites More sharing options...
moray james Posted November 25, 2012 Author Share Posted November 25, 2012 David that's correct an official ping pong ball (stamped official) is 40 mm dia. and the non official ping pong balls are 38mm in dia. I will measure more accurately and provide some additional details by the time you get the parts that you need. Best regards Moray James. Quote Link to comment Share on other sites More sharing options...
mark1101 Posted November 26, 2012 Share Posted November 26, 2012 Hey Dave............you might be interested in some of this stuff........http://www.machinadynamica.com/index.html You haven't heard anything till you've tried the teleportation tweak plus the signature version of the clever little clock (hint: for best results you need both simultaneously). Quote Link to comment Share on other sites More sharing options...
Don Richard Posted November 26, 2012 Share Posted November 26, 2012 I have had my 15 amp circuit breaker (that supplies power to the audio system) Quantum Tunneled and the effect is audible immediately and is not subtle. How can a process used to manufacture semiconductor devices affect a conductor except to negatively affect it's ability to conduct ? Unless it is snake oil marketing and not actual quantum tunnelling. You say it has an audible effect, but is it an actual improvement or just a change? Quote Link to comment Share on other sites More sharing options...
Arkytype Posted November 26, 2012 Share Posted November 26, 2012 Quote Link to comment Share on other sites More sharing options...
Don Richard Posted November 26, 2012 Share Posted November 26, 2012 So to get away from worthless tweaks and return to the OP's question, I have changed diaphragms in compression drivers to ones made of different materials with mostly good results. There is a lot of science that goes into compression driver design that is well beyond the abilities of DIYers. If a plane wave tube and appropriate measurement equipment is not available it is difficult to impossible to characterize compression driver modifications and predict their performance. Kind of like looking for germs without a microscope. I have tried different drivers on horns with mixed results. I have tried to get a K-400 to go two-way with no success. The same driver on a horn specifically designed for that driver was golden. Matching drivers with horns seems to be the way to go and a room full of test equipment is not absolutely necessary to tell if a worthwhile improvement has been made, although measurement capability can speed up the process. Measurement is necessary when EQing a CD horn where there are no manufacturer's settings for a particular driver/horn combination or for doing system alignments (delays, EQ, and phase correction) when bi/triamping is used. Quote Link to comment Share on other sites More sharing options...
Horatio Posted November 26, 2012 Share Posted November 26, 2012 OK, that link led to about the funniest audio site I've been on in quite some time! Quote Link to comment Share on other sites More sharing options...
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