For the last twelve months, I have been involved in designing speakers again after a 30 years hibernation! I can't tell you just yet what I have been up to, but give it another month and I will able to reveal what kept me busy in my spare time: as they say, if you want something done, talk to a busy person... A side effect of the research I have done on this project, commissioned by one of my day job client, is that I had to do a lot of research on which drivers are available today. One area where I found an interesting improvement is tweeters. Well, obviously we have all heard of diamond, beryllium, various other metals but interestingly enough, the more mundane silk or "plastic" variety has been completely revamped with the view of extending the frequency range beyond 20KHz and often also extending the range at the bottom of the range, with resonant frequencies lowered as low as 1kHz and with a often a very low raise in impedance around that frequency. The result is that, even though I like to use a cut-off frequency around 5kHz, the resonant frequency is now two octaves below that cutoff and then in theory 24db down, basically not audible anymore. The proprietary Audax boomer we used in the Microphase SATs is basically flat to 10kHz, so any breakup modes would be at least one octave over the cutoff frequency and then 12 db down let say around 15 to 20kHz, way beyond what most people can hear. Another interesting new parameter is the consumer demand for a much better sound in their cars, right from the start and with the manufacturer's pre-installed gear. This new market has driven a lot of research by Tymphany (Vifa+SEAS+Peerless) to produce very affordable tweeters with a very small footprint. The next challenge was to find a driver that would work without modifying the existing filter. I wanted the potential client - you, dear reader - to be able to unsolder the current Audax TW51 and fit the new driver in minutes and be assured the results would be consistent with my tests here in Sydney.. I then had my new speaker cabinet supplier to make me a quantity of new flanges that would "simulate" the flange of the TW51. This was achieved with a 3mm birth plywood CNCed to fit both the original flange and the new VIFA tweeter. Final touch is the replacement of the rather "cheap" screws on the original product with cap screws similar to the one used on the boomer. Et voilà! The procedure is quite simple: unscrew the 4 Philips head screw with the appropriate screwdriver. Use the supplied Allen key or a thin blade to extract the tweeter. Unsolder the wires. Note that the negative wire (normally black or blue) is connected to the positive lead of the tweeter. This is very important to respect, as we are using a 2nd order Linkwitz-Riley filter. Unpack the new tweeter and unscrew the cap screws almost entirely and rest the tweeter on them to protect the dome during the rewiring process. Rewire the black wire to the positive terminal of the VIFA (marked in red and the wider one as well) and the yellow wire to the negative terminal. Note that the back of the unit is quite messy as we have chosen to use silicone instead of glue to attach the tweeter to the flange, so you could change it later if you were to blow it...yes, shit happens! Also note that I cannot guarantee that all units are wired with the same colours. Some might be blue and red for instance, but it should be quite obvious. Once the wiring is done, flip the tweeter over and screw it in place using the Allen key provided. You will have to use some strength about halfway through, as the screw needs to make it way into the timber. The new screws are longer and slightly bigger than the original ones. Be careful not to touch the dome or scratch the timber edge of the boomer baffle. Also, hold on to the Allen key firmly to prevent the very strong magnet to attract the key and possibly crash it on to the dome. If this were to happen, just wait for the dome to come back to its original shape and you should be OK, but don't try your luck unnecessarily! Repeat on the other unit. Et voilà! you are ready to listen to your favourite music with renewed interest and a much better pair of Microphase SATs. Our next step will be to upgrade the SWS subwoofer. but in the meantime go to our brand new shop and...
A bit of valves indulgence...Let me say first that as most of us geeks and idiophiles we love looking at valve amps and we carry that romantic notion that they sound better than solid state. Being an electronic engineer by trade, and looking at test results alone, I will have to disappoint a lot of people by saying that there is NO technical way they can sound better. I will try to prove my point in a minute. But before I do, let me recount an experience that let me in doubt of that statement. A few years back, I have spent an afternoon listening to Tosca valve amps teamed up with Ocellia speakers and I have to admit that I did throughly enjoyed myself, almost missing my plane back to Sydney. You read the whole story on my "Interviews" page. Now, you will find below some very troubling comparisons that I have extracted from the Australian Hifi Magazine. I don't recall anybody doing such a comparison before. And let me state that what I am about to present is NOT intended to belittle or promote the chosen products. Neither is it a reflexion on the reviewer(s) involved. Some might think so when they see me using Bryston as a solid state reference, and yes there is a certain level of bias here (sic) as I know very well and use a Bryston 3B in my system. These two products have similar usage and pricing and both are very well engineered and built, and the Audio Space looks almost like a Nagra on steroids - very sexy indeed! So here we are: Audio Space Reference 3.1 (300B) - price in Oz 5.480$ Transient response is very limited by the high frequency roll off of the circuitry and the limitations of the output transformers, the bass response is truncated due to the necessary coupling capacitors between stages and the harmonic distortion is quite high, all these factors contributing to the rather mellifluous sound, a trademark of valve amps. These results are fairly typical of most valve amps. This is just an example of one which is actually very well built and deemed excellent on listening tests. Read the whole review here: http://www.avhub.com.au/images/stories/australian-hifi/reviews/2013/2013-09/audio_space_ref_3p1_amp_review_test_lores.pdf Bryston 135-SST2 - price in Oz 5,999$On the the other hand, solid state gives you near perfect transient response throughout the usable bandwidth, with some ringing only on a capacitive load. Note that on a such a load the valve amp is actually working better than on a resistive load, hence the reason why they are deemed to work so well with electrostatic panels. Harmonic distortion on the solid state amp is buried in the overall very low noise of the amp. Read the whole review here: http://www.avhub.com.au/images/stories/australian-hifi/reviews/2013/2013-05/bryston_b135sst2_amplifier_review_test_lo-res.pdf In conclusion:Both amps were deemed to be excellent on listening tests and the jury is still out there on which technology is better. My particular taste in the way I like music reproduced is one leaning towards "realism" and "accuracy", rather than "musicality". In most cases I find the rendition of the music I listen to more satisfying on a good solid state amplifier. But, as a journalist, I am interested in both technologies, and as a photographer, I am much more inclined to shoot valve porn than surgical solid state - although Dan D'Agostino gets my photographic juices flowing... So without further ado, here are a few of these pictures taken at the Show I hope you have enjoyed the journey through this Show review. Stay tuned as I am about to make a major announcement in the days to come. And yes, it might be a Christmas present for the lucky owners of Microphase speakers - hopefully some are still alive!!!
SpeakersWell, this is always my favourite part of going to any hifi show. I am still fascinated after more than four decades being in the trade to see how many people are still designing new - or not so new - speakers of all sorts of technologies, shape, size and colour. i often caught myself inventing new speakers in my head - sometime putting these ideas on paper and more recently going to the prototype phase. Trust me, it is a disease, and it is highly contagious! So you have been warned... This show, I concentrated on a few favourites and also on some brands that I never had a chance to listen to properly. So here they are without further ado. Speakers from OZThe best speakers at the Show - and they are Australians - Kyron AudioWell, call me biased, but I have watched Lee and Leon for three years now, going about their business of designing the best possible speaker in the World, and I was suitably impressed by their first product introduced here in Melbourne two years ago: the Gaia. Based on the open baffle principle and inspired by Siegfried Linkwittz, it integrated the best techniques of analog compensation for the baas, digital filtering and equalisation from DEXQ, also based in Melbourne, as well as Hypex Class D amplifiers, the best implementation of that technology by its inventor. At 180K$, nobody was expecting to sell hundreds and it didn't! But, Lee and Leon were not going to be stopped by limited commercial success, so they started designing a new product, much less expensive, smaller and with a much better WAF index. Enter the Kronos, a great example of design along the lines of form follows function. It is impeccably manufactured, the electronics have actually improved compared to the Gaia, and it comes at less than half the price! As far as I concerned, it is the most accurate, transparent and musical speaker I have listened to so far. You might have to sell an investment property to afford it, but it is definitely worth your money. Besides, you just need to add a source, CD, Steamer, or a good old turntable and phono stage. Enough talk, go and arrange a listen... We listened to my French percussionist, so I could properly compared to the Wilson Audio, and the Kronos won! Other notable speakersOur next and final episode will be dedicated to valves, not because I am a big fan, but because they can be very beautiful objects...Stay tuned!
SourcesMore and more people were using digital files on iPads, PCs, Macs, streamers of all sorts, so it was quite frustrating to see just a few CD players and a reasonable quantity of turntables. Here is my selection. The British contingent: Naim and Cambridge Audio A treat to finish this post: Wilson Audio, dcs Vivaldi, Clearaudio and D'AgostinoThis is - give or take a few components - Ken Kessler's reference system. He calls the D'Agostino suite of products the best amplification in the World. We listened to a French percussionist that I carried around the Show - virtually - on a USB stick. It is a live recording and although it is "only" 16/44.1Khz it is one of the most amazing recording I have heard - period! It was sent to me with my old buddy, Alain Wacquet, who knows the artist personally. There is a passage where there is quite a rolling of drums and the D'Agostino got a bit of a workout...see photo of the power meter below. And I couldn't capture the highest peak 2/3 to the right...
It was certainly an amazing rendition and for my first encounter with that combination of two iconic products, I was certainly not disappointed, but...you will have to come back tomorrow for a bit of a surprise! The Venue: Intercontinental Hotel at Rialto TowersOne can count on Melbourne for classy architecture! And this renovation is certainly the proof in the pudding. On top, we had fabulous weather and the best coffee - although expensive - and a very decent buffet lunch to break the - long - day... I flew in just for the day on the second Virgin Australia flight - together with Len Wallis by chance - and returned on the last flight - a 16-hour day but well worth the effort. Before I go any further, I would like to apologise in advance for the poor quality of some of my photos. My dear Olympus PEL-1 is showing signs of ageing - well, it is MY camera after all - and its autofocus is very poor in low lighting conditions. Thanks God, Christmas is not too far away! Where are the French???Not that I was expecting to see a lot of French products here, but it is always good to reconnect with some of my compatriots and French products. The disappointment came from the absence of Cabasse, Triangle and Waterfall Audio. However, it was a surprise to see YBA now distributed in Australia by Audio Heaven and Elipson by Audio Dynamics who are also starting to distribute Davis Acoustics, the company founded by the late Michel Visan and now run by his wife and his two sons. Focal was there as usual in the good hands of Audio Marketing and the big noise was coming from Devialet, also imported by Audio Heaven and Avation. Even VAF was using them for driving their fabulous loudspeakers! Even, Doug Graham from Naim Audio came in for a listen - or did he see the writing on the wall and tried to get a new job? It would be a good way to rekindle the Auld Alliance! Just kidding... French Electronics: Devialet, YBAFrench Speakers: Focal, Elipson, Davis AcousticsStay tuned for more reviews in the coming days! Melbourne Hifi Show - October 18th - 20th, 2013 - Don't miss Kronos the new baby of Kyron Audio!17/10/2013 If you have a tight schedule at the Show, then go straight to Room 312 to listen to the new Kronos by Kyron Audio.
You know of my keen interest for open baffle speaker and having had inside information about this new "baby' - so to speak, compared to the Gaia... - and I have been trepidating for some time in anticipation. A last minute impediment almost prevented me to attend the Show, but I managed to spare Saturday to pay Lee and Leon a visit at the Intercontinental at the Rialto Towers. Unfortunately, there will be no time to try "Vue du Monde" the famous restaurant of Shannon Bennett on top of one these towers. The Kronos are a fabulous contraption with a 300% raise in their WAF compared to the Gaia. It will help that there also a tad less expensive... Another exhibit that I missed in Paris and Melbourne two years ago was the Dan D'Agostino stand. It was static in Paris (go figure...) and ran out of time at the last Show in Melbourne. Glad I waited, though as we now have a full range of products, including the recently released preamp. Ken Kessler reckons this is the best amplification in the World. Let's see if I am trading in my Bryston - don't worry too much Brian! - They will be in Room 440. Bryston will have a big room called "Stock", Another amplifier worth your time is Devialet shown in rooms 403 and 410 and one of the few French companies present at the Show, in good company with Elipson and Focal. Cabasse and Waterfall seem to be absent from the Show Guide, but we might have a last minute surprise! I will tell you all about the Show next week! Before...Before my intervention, one of the drivers was dead and the tweeter was filtered by a nasty electrolytic capacitor and its level was far too high, resulting in very harsh sound. I first replaced the main driver that I found at WES in Ashfield and I calculated a better crossover for the tweeter. a simple resistor network and better capacitors. The result is quite satisfactory. And after...And here is the result...much better
They are now used by my son with a very old MOSFET amplifier and a Bluetooth receiver fed by his iTunes.... During the last stages of our conversations, and after finally finding the real configuration for the Integrales crossover, Perry G shouted a last letter to PE Leon in the hope, I guess, to see our efforts vindicated. And this time, he got a response from a newly appointed export manager, promising to send the proper schematics, as soon as PE Leon came back from a trip. Although at first, Perry though that might well be another dilatory measure, he was quite surprised to receive that information a couple of weeks after, without to have to ask for it again... So, Perry was quite chuffed, and I was quite happy that this beautiful vintage document - nobody was using CAD then - which, after a bit of deciphering, proved to be exactly what I revealed in Episode 6.
So, it is a great story with a happy ending and I hope that Perry will now enjoy his renovated speakers for years to come. I have been told that he might even put his beloved Audio Research amp in service, after having replaced all the valves and put the whole thing through a serious burn-in session! Hopefully, we will hear from him about the renewed pleasures of listening music on a fabulous set of vintage HiFi! I hope you have enjoyed our journey and the story and would welcome any other enquiries into helping other vintage enthusiasts willing to restore or upgrade a beloved pair of speakers. After Perry's elogious email, I was obviously quite happy with the result, and I thought it would be good to review everything to document the process and make sure we were the closest possible from the original. During that process I realised I had possibly made a mistake by positioning the resistor network BEFORE the filter cell, rather than AFTER as per diagram above, which is more "textbook" if you like. This topology gives the ouput of the cell a more stable impedance and make it easier to tune the cut off frequency of each cell.. We tried various iterations of this topology, swapping the resistor values to adjust the relative levels of the midrange and tweeter, and I guess I confused Perry quite a lot in the process, without necessarily getting a better result on listening tests. The FFT above gives a good indication of the quite good response and is consistent with the listening tests Perry was reporting back to me. Obviously, I had to trust him entirely on his ability to remember how the speakers sounded more than 10 years before, but I believe that if you are familiar enough with a particular set up and a few recordings, you can have a fairly good assessment of the result you are after. But a few days later, we had a breakthrough, actually two...but let's start with the cruncher! Perry had spotted on eBay another pair of Integrales for sale in Canada, and I think at one point he may have been tempted to buy them...but in his infinite wisdom, he had the genius idea to ask the seller for a photo of HIS crossover and the seller kindly agreed! The most interesting thing about this photo is the resistor on the top right: it is not quite as burnt as in Perry's speakers - maybe the party didn't go as long, or the music was played as loud, or they ran out of beer!!!! - who knows? Nevertheless, it means that this resistor should have been specified with a higher poet rating in the first place, and we will understand why soon! The other good thing about this photo is that the filter has not been tampered with and is obviously as per the original design. So, then I spent some time decrypting it and came up with a new schematic - see below: From this diagramm, it is easy to see that that R1 takes half of the power going into the midrange and should have been specified as a 10w at least, and in doing so, I would not have a chance to play and make anew friend across the Pacific Ocean! The good news are that when Perry had implemented this new crossover, he was on top of the moon with the auditive results, like being reunited with an old love! Here are the corresponding measurements: We have not quite figured out why there is so much difference between the two speakers, but one suggestion is that one speaker is positioned in a corner of the room where the other one is not. Well, you see, after more than six months of correspondence, trial and errors and a bit of luck in the end, we managed to bring these PEL Integrale back to life. Perry is now in the process of getting his Acoustic Research amp back to its original grandeur and I have not heard if it is back in service or not, but that should give another level of smoothness to the sound of these iconic speakers.
Now I promised you that there was a final twist in the story...well I will keep that for our next and last episode 7, next week! Stay tuned... At that stage, I thought I had enough information to come up with a proper schematic of how and why. the filter should be wired. This wiring diagram uses all the right components, and are properly allocated to the right filter cell. A few calculations confirmed that the woofers were cut off at 400Hz and the tweeter at 6 KHz, which souns quite high, but I personally like to use a higher cut off frequency and also the curves I found for the tweeter were consistent with this design decision. The midrange is not filtered in the treble as it gently rolls off naturally I suspected, as I could not find any measurements for the SEAS midrange P14RC4, pictured below as well as the mighty FOCAL 8C412 woofer. I have since found a data sheet - which confirms my guess - here: http://www.seas.no/images/stories/vintage/pdfdataheet/h0522_mp14rcyp.pdf By the time Perry got a chance to rewire his crossovers to this schematic, he also had received his iTestMic and we moved on to using the FFT measurements: And I got this lovely email with this FFT photo - I have to say I was quite chuffed...:
"This Jean-Marie is the one that sounds the best by far. It was immediately obvious as so superior to the "correct" tweeter phase which was supposed to be inverted according to the very first schematic from PEL. Of course that schematic was for an old version of the crossover which was not the same as mine. The white curve is the "inverted" phase while the orange curve is the "correct" phase. You cannot believe my happiness after so many years of trying and giving up, tearing apart and cobbling back together, sure that this would be the last time. Hours on the internet corresponding to people who didn't know anything. Suggestion after suggestion. Now finally, this is it. How can I thank you enough? You are a freaking speaker genius.!!! (bold inserted by author...)" Perry G. Although the saga continued for a while more, let's leave it at that for today! |
AuthorBorn in France, well travelled, relocated to Sydney in 1997. Archives
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