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    go to Diy Loudspeaker Projects by Troels Gravesen Due to excessive traffic at this website please use the above link and make this your default page if you have plans
    http://www.troelsgravesen.dk/ (2013-02-26)


  • DIY Loudspeakers
    830860 XT25TG built by Orazio Silcily Italy Link to his website 06 06 2012 CNO mkII built Young South Korea 06 06 2012 ScanSpeak W1500 97 built by Peter The Netherlands 30 05 2012 CNO T25 built by Ladislav Slovakia 28 05 2012 DTQWT built by Valery Russia 25 05 2012 QUATTRO transmission line built by Niels Denmark 23 05 2012 Acapella SE built by Mar China 17 05 2012 SP44 built by Torsten Germany 13 05 2012 Large 3 way built by John US Based on PHL 5011 JA8008 and SEAS T35 13 05 2012 TQWT built by Daniel Denmark 06 05 2012 Peerless 830860 built by Tomas Spain 03 05 2012 Ekta built by Alan UK 22 04 2012 DTQWT built by Nicola Italy 15 04 2012 CNO 25 built by James Stunning cabinet work 14 04 2012 Ekta built by NNN Italy 13 04 2012 3 Way Classic built by Victor Ukraine 10 04 2012 Ekta Grande built by Dean US 04 04 2012 Ellam XT built by Omar Mexico 19 03 2012 Response from Wendy US on JBL Up Grade Kit 15 03 2012 Totally Stoned 3 Way Classic built by Federico Italy 28 02 2012 Ellam XT built by Girmantas Lithuania 28 02 2012 CNO 25 built by Ryno South Africa 21 02 2012 CNO 25 built by Mehmet 19 02 2012 Jenzen SEAS ER built by Gerrit NL 08 02 2012 SEAS W15LY001 22TAF G built by Daniel Russia 25 01 2012 Ellam 98 built by Tom Australia 24 01 2012 Jensen 1071 built by Yetkin Turkey 20 01 2012 QUATTRO built by Ben US 16 01 2012 TQWT built by Steve UK 09 01 2012 Ekta Grande built by Tim Australia 08 01 2012 OBL 11 built by Carl UK 08 01 2012 Ekta Grande built by Petr Czech Republic 04 01 2012 CS Monitor built by Chris 03 01 2012 NOMEX 164 built by Ed 02 01 2012 SEAS 2½ way CA18RNX built by Kimon AU Go to builders response before 2012 Back to Index HES High Efficiency Speaker Constructions Click heading to go to overview of HES constructions Click image to go to HES speakers introduction Read feedback from HES builders here http www troelsgravesen dk Builder s response htm TQWT mkII 2 way tapered quarter wave design JA8008 TW034 waveguide DTQWT mkII 3 way double tapered quarter wave design JA8008 TW034 waveguide 2 x Eminence Deltalite II 2510 DTQWT mkII 12 12 inch version of DTQWT mkII JA8008 TW034 waveguide 2 x Eminence Deltalite II 2512 8008 CENTER for the complete 8008 surround set built around JA8008 TW034 drivers Tweaking the DTQWT incl intro to TQWT mkII and DTQWT mkII QUATTRO 2 way monitor standmount from JA8008 TW034wg drivers Not exactly high efficiency 90 dB but belongs to the family of TQWT DTQWT OB 9 and OBL 11 OBL 11 Open Baffle Loudspeaker My homage to Gilbert A Briggs SFB JA8008 TW034 and Eminence Deltalite II 2515 fully passive crossover OB 09 open baffle construction JA8008 TW034 and Eminence Deltalite II 2515 15 bass driver OB 07 open baffle experiments Supravox 215RTF JBL LE26 waveguide Goodmans Axiom 150 mkII DTQWT experiments JBL LE26 waveguide Goodmans Axiom 150 mkII Supravox 215RTF Amps for TQWT and DTQWT some general thoughts on suitable amplifiers DTQWT 10 or 12 inch Which should I build Back to Index Accuton Constructions Jenzen Accu Accuton C173 6 191E Accuton C30 6 024 Audio Technology 10C77 25 10 KAP Jenzen D mkII Accuton C173 6 191E Jantzen JDT 1024 AudioTechnology 10C77 25 10 KAP I consider the Accuton the main driver here SEAS Constructions Click heading or image to go to SEAS constructions overview Back to Index 3 WAY CONSTRUCTIONS 50 LITER Jenzen SEAS NEXT T25 and T29 The luxury versions of Jenzen SEAS ER Jenzen SEAS ER and CA constructions Making high end sound from budget drivers Cyclop W26FX002 M15CH002 T29CF002 3 WAY CONSTRUCTIONS 30 50 LITER Acapella NEXT W22NY001 W18NX001 T29CF001 Acapella SEas W22EX001 W18EX001 T25C003 Acapella SE single pdf file Acapella LWJ Acapella SE and Acapella SEas constructions pdf download Acapella SE drawings zip file Point75i SEAS L22RN4X P W15CY001 Expolinear NDRL81 Point75A B ScanSpeak 18W 8535 SEAS W15CY001 Expolinear NDRL81 alt NEO3PDR pdf Poor Man s Strad CA22RNX MCA15RCY T27TFFC Poor Man s Strad EXCEL W22EX001 W15CY001 27TFFC 3W Classic CA22RNX MCA12RC 27TFFC TJL3W W18E001 W12CY001 HIQUPHON OWI download TJL3W large graphics zip file TJL3W W18E001 W12CY001 Fountek JP3 2½ WAY CONSTRUCTIONS 20 35 LITER CNO 25 2½ way CNO x W18NX001 T29CF002 CA18RNX 2½ way floorstander 2 x CA18RNX 27TDC 2 WAY CONSTRUCTIONS 15 30 LITER CNO mkII W18NX001 T29CF002 CNO T25 W18NX001 T25C003 MAYA CA18RNX T25C003 SEAS TOK tweeter overkill CA18RNX T29CF002 CA18RLY 22TAF G COMPACT TJL2W W18E001 Fountek JP3 MINIS 4 8 LITER SEAS CURV mini two way from SEAS U16 RCY P and SEAS 29 TFF W Scoperta mini TLs W15LY001 Peerless HDS SEAS 5INCH minis CA15RLY W15CY001 W15LY001 22 TAF G Eekels minis W12CY003 22TAF G W15CY001 Hiquphon OWI W15CY001 NeoCD3 DISCONTINUED T14RCY SS 8513 or Hiquphon OWI T14RCY discontinued SEAS W17EX001 SS 8513 W11XT W11CY001 Back to Index Scan Speak Constructions Click heading or image to go to ScanSpeak constructions overview 3 way constructions 50 litres Jenzen Illuminator 3 way TL design from ScanSpeak W26 8861T00 18WU 8741 T00 and D3004 660000 Ekta Grande 18W 8531 G00 12M 4631 00 R2904 7000 or Vifa XT25TG 30 04 Jensen 1071 3 way 26W 8861T00 18W 8531 G00 D2905 9900 Jazzman 3 way from W22 8857T00 15W 8530 K00 Vifa XT25TG 3 way floorstanders max 35 litre Ekta 18W 8531 G00 12M 4631 00 R2904 7000 or Vifa XT25TG 30 04 SP44 3 way 18W 8530 G00 Accuton C44 Hiquphon OWI SP38 13 18W 8531 G00 D3806 8200 D2010 8513 2 way floorstanders max 35 litre Illumina 66 two way floorstander from ScanSpeak 18WU 4741T00 and D3004 660000 or R3004 662000 SP95 18W 8531 G00 D2905 9500 Amish 45 95
    http://www.troelsgravesen.dk/Diy_Loudspeaker_Projects.htm (2013-02-26)

  • Speakers Corner
    by the end of August and what s next is to be seen At least 4 speakers are on the drawing board and two of these are low cost 2 and 3 way designs And finally I found a Lenco L75 turntable in close to mint condition I m very much looking forward to restoring this spinner with a new plinth and 12 Jelko tonearm Based on overall construction and principle idler wheel this turntable should work as well as my Garrard 401 The best speaker I ve built Some people question my statement that the DTQWT is the best speaker I ve ever made because I ve made quite a few speakers since then and how can I still hold this opinion despite Jenzen D etc Well the DTQWTs can do things none of the other speakers can do in terms of overall dynamics due to efficiency mid tweeter integration and because they don t have a crossover in the critical midrange These are the three main features The DTQWTs can play a piano an oboe a flute and a saxophone louder than any of the other speakers partly due to the large midrange driver 8 and the large wave guided 34 mm dome tweeter Size matters and regardless of the quality of a 5 6 midrange driver there are limits to how loud they can play The Jenzens all have less dynamic head room due to these limitations although satisfactory for most applications average living room size The DTQWTs can be played to satisfatory levels with my 45 watts SET amps something none of the other speakers can do and my 6C33 valves sounds better than my solid state amps And some mistakenly think the DTQWT are only suited for low wattage valve amps because they were developed for this but any good amp can be used with the DTQWTs they may just not sound as good as they could if you had a good triode amp There are reasons people bother nurturing valve amps as some require regular service but we don t get it all for nothing So the DTQWTs are still my best speakers regardless of cost and specific areas where some of the others may excel All speakers are compromises and fortunately the amount of speaker designs seems unendless and there should be one for your taste too 09 06 2012 The Jenzen Illuminator has been launched and I m pleased with the result The 26W bass driver goes deeper than any of the other Jenzens the price to pay is reduced efficiency and the Illuminator needs a sturdy power amplifier to bring out the best I ve had regrets that the 6640 Be dome wasn t used but this tweeter just didn t perform well in this set up due to a reach out here I am quality I wasn t able to handle in the crossover As always driver matching has to be tried before any given combination is certain The 6600 tweeter was doing exactly what I wanted it to do playing treble and nothing more The 6640 will be tried in other speakers to come Next in line is a 30 liter two way from ScanSpeak 18WU 4741T00 and again the D3004 660000 tweeter D3004 662000 as an alternative Crossover simulation suggests several interesting options and I looking forward to this most interesting part of the project 28 03 2012 Springtime temperatures should call for garden work and preparing for this year s vegetable garden and so it does but speaker work is continuing as I have exiting ScanSpeak constructions in pipeline Up coming is a Jenzen Illuminator and the preliminary work is finished that is getting the acoustic offset of mid and tweeter right and testing if my preferred crossover topology will work and it does In fact the 18WU driver has an excellent frequency response on the Jenzen baffle making crossover work easy and simple The tweeter will be the beryllium dome and I m keen to learn how good it is in comparison with my current diamond tweeter Accuton set up My Jenzen Diamonds will be disassembled as I need the basic Jenzen cabs for the Illuminator speaker and the diamonds will have their reincarnation in new cabs later this year I need these for reference as the deliver the best mid tweeter level of transparency I ve yet experienced and numerous visitors have confirmed this After the Jenzen Illuminator there will be smaller two and three way floor standers from the 18WU drivers and I will also use the 4 ohms version of the 18WU drivers to increase system sensitivity maybe not for low wattage valve lovers but speakers in this category will never be my first recommendation for less than 50 wpc amps An adaptor for mating the ScanSpeak 7100 tweeter with my TW034 waveguide have been tried in my DTQWT speakers offering enhanced resolution and transparency but maybe not the overall coherent sound from the 8008 TW034 Making waveguides is on and off and never really ends as new ideas emerge from time to time in order to improve performance So lots of projects in pipeline only building cabs takes time This winter s live performances included Ravel s Piano Concerto in G major at the local Symphony Hall featuring an American pianist Simone Dinnerstein and it kept us all spell bound for the entire length of the concert Look out for this lady she s something The first movement in this piano concert really holds elements of Rhapsody in Blue by Gershwin and I guess Ravel did listen to contemporary jazz music after moving to the US and I wouldn t be surprised if Keith Jarrett digs into some Ravel piano recordings from time to time 15 04 2012 In response to my comments above Piotr Poland provided this article by Robert Rogers Oxford Journals on Jazz Influence on French Music 4MB Thanks to Piotr 02 02 2012 January and February for sure are diy speaker months The cold winter months call people to the workshops cutting sheets for cabs reading diy websites and making all sorts of plans Well it also tells most diy business is taking place on the Northern hemisphere as least based on website statistics and mails received What I have noticed over the last 2 3 months is that I get more and more mails I can t answer properly Questions about strange speakers I ve never even heard of or how I think a given speaker will interact with a given room The latter is really impossible to answer Whether you buy a pair of speakers or build them yourself you always run the risk of total failure due to poor room acoustics Too much bass or too little bass are the typical problems and I m mostly short of suggestions as the only information I have is basic room dimensions Quests for building finished speakers are another frequent topic and having a full time job this is out of the question I can hardly cope with my own plans and have ideas for years to come Sorry ScanSpeak tweeters have kept me busy and I have launched some measurements and an article on a waveguide for ScanSpeak D2904 710003 tweeter This waveguided tweeter was tested in the DTQWT construction and for the first time found suitable as an alternative for Audax TW034 Better Hmm different and in the end a matter of taste and definitely more expensive Out of curiosity I also bought a line stage kit from diyhifisupply and I can fully recommend this product which can be had for down to 300 USD two good coupling caps Not a bad entry into the valve world and it should be trouble free for years and years This line stage together with an e g JungSon Duro class A amp is an unbeatable combination in terms of cost performance and can be realised for close to 1000 USD Today we can have high performance gear at price that was unthinkable only a decade ago Last but not least someone lend me a pair of ScanSpeak 18WU 8741T00 drivers and what was planned as a quick review of one of the Illuminator series turned into weeks of crossover tweaking Eventually a pair of stand mount monitors was the result Being used to DTQWT and Jenzen speakers it took some time to get used to a small 6 1 again 150 square centimeters of pulp really can t move a lot of air thus numerous crossovers were made before I was satisfied and it gave ideas for future experiments The Illuminator drivers are not as smooth compared to the Revelator drivers and extra care is needed in crossover design but these sandwich membranes deliver details former drivers may have been short of Value for money Doesn t make sense You re buying a specialty product with specific design features and you have to pay And never judge a product based on measurements alone It may takes many constructions and endless crossovers to get to know a product s full potential Check out this interview of Neil Young talking about the inadaquacy of MP3 files and low fi Do you know what kind of media Steve Jobs listened to when at home Thanks to Max Norway for sending the link 05 12 2011 November seems a busy month on speaker building The number of mails have been overwhelming Hope some of you got sensible and helpful responses I know some of you didn t because of what is described here crossovers and this choices but that s how it is I can t tell if drivers I don t know from own experience will make a good system and most of you writing appear not having measuring equipment to get the crossover right and even the best drivers can be a waste of money without a good crossover design Launching the Jenzen Accu wasn t easy This is a seriously expensive speaker and I can t help wondering if someone building the Accu will think it s worth the money So I had to ask myself if it feels right for me and after several weeks audition and drivers breaking in I felt it was right I ve missed it every time I had something else running and it makes me confident it s worth while With a speaker like this you have to get past new speaker honeymoon to know if it is right I always seriously doubt break in as most break in is taking place in out brains but I think the Accutons need some break in A little rough and edgy at first but smooth and homogenous after many hours of playing The AudioTechnology bass driver is everything I d hoped for in the TL cabinet Articulate and dynamic even at low levels I recently visited a guy having a pair of small stand mount ScanSpeak 18W 8531 G00 D2904 700005 speakers in nice black piano lacquer finish Gamut He paid more for these speaker than the total cost of the Jenzen Accu Now the Jenzen Accu does take several times the space but comparatively the Jenzen kit is a steal for the money if you can handle the woodwork With the Jenzen Accu I will also start a practice of writing something about the limitations of my speaker constructions which may discourage a few builders but limitation is part of every speaker design I have done this before on very small speakers Based on response I can see that people often overestimate the soundstage a given speaker can produce Some people think a small and inefficient speaker just needs a huge amp to get it going and it may certainly help on some parametres but it doesn t change the fact that a given speaker is limited by the amount of air it can move as a result of the total membrane area A midrange driver really shouldn t move much in fact cone movement should hardly be visible even when played loud Same thing for bass drivers Visitors are always surprised seeing and feeling the cones of the two 10 bass drivers in the DTQWT when played really loud They barely move 1 mm and they shouldn t I would really have liked to launch the Jenzen Accu with the final front panels but the Jenzen cabs will see more drivers before they ll end up as the final Jenzen Accu because the Accu is likely to be the final statement of the Jenzen series This is kind of a problem because the incitement to make more Jenzens is diminished by these drivers How can I make something better because we always want to make something better Well the AudioTechnology version may throw a few surprises too I hope to have a 18H52 built for midrange with a suitable impedance not needing any attenuation at all The Accuton C173 6 191E didn t and it pays off There won t be more speakers launched this year and I think the Accu is a nice finale to a fruitful 2011 in trying out stepped baffles and simplified crossover topologies improving overall performance Last but not least I ve already had a number of mails asking if a 20 30 watt PP SET valve amp can drive the Jenzens speakers To my mind they can t On average we re some 6 dB below e g DTQWT sensitivity and we need at least 4 times the amount of power comparatively The 80 watt Jungson does really well and generally I recommend 100 wpc being valve or solid state for the Jenzens Maybe a really good 60 70 watt PP valve amp will do well too but I don t have such a thing and can t guarantee I also want to stress the importance of quality of the amp in particular for the Accu version Only a few days ago I had a visitor bringing in an Advantage S150 solid state amp from Bladelius Now this is a nice and powerfull amp easy on the ear and with a wide soundstage but it seriously missed the holographic reach out midrange magic The Accus can reveal much more than this amp is capable of doing and the JungSon outperformed it over and over again despite costing a fraction of the price I only use the power amp section of the Jungson amp 01 11 2011 Loudspeakers we don t come across every day One with limited dynamic capability and one with almost unlimited dynamic capability I ve had the opportunity to review the Manger MSW transducers and my expectations were high I had hoped these one of a kind drivers had the answer to phase distortion and impulse correctness but I was seriously disapointed These drivers have a high magnitude of nonlinear distortion and fortunately I found another article confirming this because after decades of praise I was a bit nervous to rock the boat I don t say these drivers are useless but they have serious limitations on terms of portraying the depth of an acoustic scenario lack of dispersion and they don t go loud before distortion becomes clearly audible o 0 o Who would think that a few kilometers from where I live there would be a JBL Paragon loudspeaker fully functioning The owner bought these back in 1975 and has only had new surrounds added to the legendary LE15 bass drivers A friend of mine set up the arrangement and we had an enjoyable hour in front the Paragon These speakers or more correctly this speaker is no less one of a kind compared to the Mangers I think the 4 375 midrange compression driver is the most powerful ever produced and mated with the 075 ring radiator and 15 bass driver this speaker is if anything a clear demonstration of what converting electrical energy into acoustic energy can mean For those unfamiliar with the Paragon design the above sketch tells what s going on The most unusual thing about this speaker is the midrange horns pointing towards a huge curved front panel meant to disperse sound into the room this quite opposite to the tweeters located inside the bass horns and pointing forward Now sitting in front of the speaker on the floor because vertical dispersion from the tweeters is limited the usual quest for soundstage depth spatial information and three dimensionality is far off Forget it This speaker makes music in a room and it does it like few Time alignment phase coherence Forget it The shocking thing is that when energy transfer is optimised way beyond what we are used to we may get away with grossly neglecting all the other parametres This doesn t mean the Paragon is the way to go because it isn t but we can go home and seriously think about ways to improve dynamic headroom and reduce distortion The inability to perform appropriate energy transfer from our rediculously small direct radiating 5 6 middrivers is pinned to the wall 14 Oct 2011 Jenzen SEAS ER and Jenzen NEXT constructions launched Pics of the finished cabs have been added If you have the time and skills in woodworking you may be in for a treat from modest priced drivers SEAS ER The NEXT version doesn t come cheap but delivers the goodies Response has been overwhelming and three ER kits were sold before the paper was dry so there seems to be quite an interest in large speakers and I feel confident going on with the work developing further Jenzen variants 26 Aug 2011 It s with great satisfaction I now lauch the Yamaha NS1000M Up grade Kit This completes the range of up grade kits covering the most noticeable speakers of the Sixties Seventies and Eighties the Tannoy MG15 the JBL L100 Century and now the Yamaha NS1000M All three speakers were made
    http://www.troelsgravesen.dk/speakertalk.htm (2013-02-26)

  • DTQWT-mkII
    compared to TQWT The typical quality of the bass from a horn is quite different from conventional high mass low efficiency bass drivers in small vented enclosures The DTQWT delivers deep dynamic and dry bass without the typical vented enclosure overhang In principle we can load the horn with any 10 bass drivers regardless of Fs but there are limits I found drivers with Fs ranging from 30 60 Hz suitable and without any noticeable difference unless the driver at the same time has high Fs and extremely low Qt e g Faital 10PR300 which on paper looked suitable but in reality didn t perform well Actually Fs was closer to 65 Hz and Qt 26 The Eminence Deltalite 2510 II proved just ideal with Fs 49 Hz and Qt 0 39 own data The length of the horn determines the lowest frequences you can expect from these kind of systems This is not a function of the driver s Fs as many may think Mind you You can have a 5 high Fs driver doing 30 Hz you only have to built a humongous exponential horn to make it happen DTQWT is designed to do 40 Hz and from the impedance graphs below you can see this is the tuning frequency of the horn making two impedance peaks like a vented system Despite the description above many people have trouble understanding why we don t need bass drivers with huge Xmax and low Fs Please compare the combined membrane area to an e g 10 bass driver in a vented cabinet with the DTQWT Here we have some 2 x 330 cm 2 from the bass drivers and 220 cm 2 from the front driver in total 880 cm 2 This is 2 6 times the membrane area of a single 10 driver If a single 10 bass reflex loaded driver has to move 5 mm we only need 5 2 6 1 9 mm Next all drivers in the DTQWT loads a horn an acoustic transformer Wikipedia A horn loudspeaker is a complete loudspeaker or loudspeaker element which uses a horn to increase the overall efficiency of the driving element typically a diaphragm driven by an electromagnet The horn itself is a passive component and does not amplify the sound from the driving element as such but rather improves the coupling efficiency between the speaker driver and the air The horn can be thought of as an acoustic transformer that provides impedance matching between the relatively dense diaphragm material and the air of low density The result is greater acoustic output from a given driver The DTQWT horn works quite different compared to a bass reflex enclosure and we do not need excessive panel thickness and I wish you could all experience how the e g side panels feel when I play bass even at thunderous levels You won t feel much Some also think the damping panel that can be added to the rear will dampen the bass output considerably It doesn t Not at all It only dampens some midrange output from the bass drivers and may be useful if you have the speakers close to the front wall I never used them despite having the speakers only 30 cm from the wall Initially the DTQWT was built with a single 10 bass driver providing a system impedance of 4 ohms minimum not something that should make most decent low wattage amps uncomfortable considering the overall system sensitivity My 20 wpc PSE mono blocks 6AS7 triodes did well but adding a second unit in series with the first driver left no doubt that the amps felt better about 6 ohms minimum Actually they felt much better and I admit I was a bit surprised by the difference Distortion was significantly reduced at very high levels and the grip on the bass drivers significantly improved Possibly the reduced cone motion from having two bass drivers also reduces back EMF back electro motive force and SET amps have low damping factor with poor grip on bass drivers compared to push pull valve amps or solid state amps Some of the components used for the DTQWT The Drivers Back to index The story behind the front drivers can be read here TQWT Left Audax TW034XO P47N tweeters Right Waveguide specially designed for TW034 Click images to view large This is diy so you have to do a little more yourself Center the tweeter on the waveguide as seen on photo Mark for holes on waveguide and add a 10 mm mark on the drill Make 3 x 10 mm holes in waveguide check if dome is properly centered and fasten with the screws supplied with the kit That s it 5 Left JA8008 extended range high efficiency driver Right Eminence DeltaLite II 2510 bass drivers for DTQWT Click images to view large Eminence DeltaLite II 2510 drivers Download PD Europe 138 EUR ea here at http www thomann de gb eminence deltalite ii 2510 htm partner id 73572 Thomann is a very reliable supplier here in Europe and has fabulous shipping rates 8 EUR for shipping from Germany to Denmark Who can beat this Go od Old England 4 x DeltaLite 2510 available here at LEAN for 405 http www lean business co uk eshop 4 x bundle eminence deltalite ii 2510 neo 8ohm 10 250watt p 1136 html 405 3504 DKK 470 actually cheaper than Thomann Delivery from 14 24 throughout Europe Not too bad USA 134 USD ea Music123 and 135 USD ea here at US Speaker Due to rising prices on neodymium China it may be worth while checking different suppliers Check out eBay as well DTQWT mkII crossover Back to index As can be seen the mid and tweeter section are the same as for the TQWT construction My default tweeter series resistor is 2 7 ohm but some may prefer more treble Having two 8 ohms drivers in series calls for a large coil
    http://www.troelsgravesen.dk/JA8008_DTQWT.htm (2013-02-26)

  • TQWT-
    speaker differs the most is in its smooth midrange and ability to reveal the dynamics of music The speed and attack it can produce is something none of all the other speakers on this website can manage It s fast and a drum solo will kick butt even from a 10 wpc amplifier The midrange is special because it comes from a large membrane and it s easy to hear and understand what singers sing This is important if you listen to lyrics in a foreign language which I mostly do This speaker can reproduce vocals it can even play vocals loud without noticeable distortion I ve made distortion measurement and even up to 110 dB 1 metre distance it s mostly dominated by 2nd order distortion at low levels No nasty distortion peaks anywhere The bass is different from most vented systems because it is short Comparatively it s short and dry like bass from a well designed closed or aperiodic box The aim of this project was to create a speaker system that could compete with high efficiency 8 full range drivers but without the shortcomings of whizzer cones necessary in this category I believe a properly engineered crossover offers significant advantages over the compromised dream of having a single diaphragm doing it all And I think I ve got it There s no midrange shout there s no 10 dB treble peaks you can t stand in the long run and there s an overall balanced presentation from the ever so important midrange important for making instruments and vocals sound right And there s an even power response over a wide area something we can never accomplish from an 8 whizzer cone fullrange driver Robustness is another important parameter when putting bits and pieces together to make a driver We often see commercial drivers made from components that really aren t sonically optimal but durability is an important issue as the least thing a manufacturer wants to experience is his product being discussed for falling apart due to improper gluing burned voice coils etc and having drivers back for re coning is not something any manufacturer looks forward to Ideally a driver should last for a couple of decades to fulfill customers expectation to quality and performance Very few drivers can make 5 decades without suffuring from sagging cones due to loss of spider elasticity The JBL 123A bass driver is probably the most durable driver I have ever experienced but a wide range of vintage drivers really do not perform as they should due to age High humidity and high temperatures are other problems to consider Last but not least Young people Sorry young folks but you have bad record for frying your voice coils Saturday evening I have to include some comments on the large dome tweeter and not least the waveguide used for making an overall smooth transition from upper mid to lower treble Having a large radiating area combined with a waveguide providing both acoustic amplification proper dispersion and reduction in distortion are all key elements in the smooth treble presentation Treble os often regarded as something above 3 kHz which is really not true It starts much earlier and proper integration of drivers is vital in any successful construction Forget any other non waveguide standard 1 dome tweeter for the JA8008 It s been tried and it doesn t reveal the potential of the JA8008 driver Not even the most exotic and expensive tweeters could handle what this large dome can do Back to top Click images to view large Click images to view large Tweeter for JA8008 back to top Sourcing a tweeter to match a 95 dB driver was quite a problem because there simply aren t many around I didn t want to use horns and ribbons Horns are too directional and ribbons have poor vertical dispersion and they didn t integrate well Some recent Vifa Peerless ScanSpeak and SEAS tweeters have decent sensitivity but rarely above 92 dB 2 8 volts I didn t want a naked tweeter I wanted a tweeter with a modest waveguide because they integrate better with the midrange due to reduced distortion at point of crossover and from providing an even power response For a system tuned to 94 95 dB sensitivity we do not necessarily need an e g 95 dB 2 8V tweeter Usually the crossover will raise the sensitivity a little but still this isn t enough Adding a waveguide to a dome tweeter will if well designed raise sensitivity 4 6 dB in the 2 8 kHz range but also lower on axis response above 10 kHz Most 1 soft dome tweeters are fairly directional above 10 kHz and applying a waveguide will often produce a more even power response hence reduce on axis response above 10 kHz Initially the vintage JBL LE26 tweeter fitted with a waveguide was used and performed very well but the LE26 is obviously not a viable option as it is no longer produced and only found on eBay The Dynaudio Esotar was tried the Monacor DT300 waveguide Vifa XT25TG waveguide one of the new SEAS EXCEL tweeters etc but none of these were as good as the JBL LE26 waveguide Nor were the SEAS high efficiency tweeters T29CF001 002 All very good tweeters in other combinations but not here Eventually the Audax TW034XO P47N tweeter was tried and turned out to be just what I was looking for A large 34 mm fabric dome driven by a huge 100 mm magnet The TW034 is actually a classic having been around for many years and well known from a range of former British studio monitors Fortunately Audax is still producing this tweeter now in a new and improved version The dome area is as big as the LE26 and integrates even better than the LE26 with the JA8008 driver By coincidence the waveguide will fit both options should you want to experiment The waveguide
    http://www.troelsgravesen.dk/JA8008.htm (2013-02-26)

  • QUATTRO
    would never have emerged from modelling alone Tweeter attenuation may be fine tuned to personal taste your front gear and room acoustics I think 4R7 is absolute minimum Try 5R6 if you find the treble too forward My default is 5R6 but I ll most likely end up with 6R0 or 6R2 giving e g piano and vocals the most natural blend of overtones 5R6 actually means treble range above 5 kHz 1 1½ dB below average midrange level I ve almost always found this voicing to produce the most natural timbre 6R0 or 6R2 are not common values 8R2 in parallel with 22R will make 5 97 ohms and 8R2 in parallel with 27 ohm will make 6 29 ohm so this may be useful 3R9 4R7 and 5R6 are included in the crossover kit so order extra if you like to experiment 3R9 is way too high treble level for my taste but some like it hot The crossover for the midwoofer is more complex as we need to lower system sensitivity by L2011 bypassed by R2011 Next we have the usual series coil here 1 2 mH bypassed by an RC circuit of 0 47 uF and 22 ohm in series Together with R2031 C2031 this helps shaping the 8008 roll off which acoustically is close to 3rd order thus we can maintain positive polarity of both drivers thanks to the added acoustic distance to the tweeter caused by the waveguide A lot of things were tried to omit the midrange notch filter R2041 C2041 L2141 but this minor 1 5 dB bump at 600 Hz just proved too much in the long run Not having the notch filter on certain recordings just made the 8008 driver say Hey look at me Some midrange huh Drivers should draw as little attention as possible Check measurement page to see what it means Link below Crossover Layout Click image to view large Wiring Click image to view large Crossover Layout Low Cost Version click image to view large Left Soldering wires to terminal tags Middle C Coil at bottom of cabinet fastened with screws through felt layer Right Both sections in place Left Damping material covering C coil at bottom Middle Main board on rear panel fastened with screws Right Damping material covering main board and side panels next to 8008 driver Measurements on finished speaker Back to top Left SPL at 1 meter 2 8 volt Overall system sensitivity 90 dB 2 8V 1 m Right Final system impedance Minimum where is matters is 8 3 ohms at 36 Hz and 160 Hz 7 ohms minimum above 7 kHz My 20 watts Audio Mirror SET amps just love these speakers For those addicted to measurements click here to view it all Cabinet construction pics Generally Never route for ports and drivers before at hand Nor drill holes for terminals before at hand Do your own measurements and make test routings before doing the actual cabinets With Baltic birch
    http://www.troelsgravesen.dk/QUATTRO.htm (2013-02-26)

  • OBL11
    the drivers from our speaker system All of a sudden we re forced to rely on our hearing alone and our brains don t have any visual information helping e g fooling our minds on what is going on OBL 11 Drivers Back to index The OBL 11 drivers Eminence DeltaLite II 2515 and JA8008 TW034 waveguide combo The JA8008 and TW034 drivers are described in detail in the TQWT file follow link here Eminence DeltaLite II 2515 15 bass driver is available from Thomann Germany here For the time being at 205 EUR each Thomann has the best shipping rates I know of so highly recommended but their prices have risen considerably due to neodym shortage 108 in the UK is more like it For the US look at PartsExpress here Alternatively US Speaker here Both dealers charge 170 USD each For UK residents look at Blue Aran here 108 Do you live in Australia Essential Audio may be a supplier look here 335 AUD each Search deltalite on page These prices are updated from time to time and may vary a lot due to China holding 95 of the world marked for rare earth metals Thanks to Mr Ranson AU for these comments Thought I d let you know that the deltalite 15 is worth buying from Thomann to send here to Australia They have a flat rate shipping of 50 euros to 30 kg You can therefore buy these drivers at 180AUD including shipping each if you buy two I m not one to take sales away from local business but that s too big a difference to ignore and thought you may want to mention this in your OB11 write up OBL 11 Crossover Back to index Crossover based on simulation I can imagine someone saying this is a bit far from Briggs single cap SFB Right In the example above I ve tried to make a crossover as if we had ideal drivers or rather I ve tried to model a response as though we had ideal drivers only needing a few components This is what it takes to make the drivers respond as I would like them to Please note there are only a few components in series with the drivers The rest is modest LCR circuits shaping the drivers roll off The result is this Nice and smooth bass LR2 roll off Perfect LR2 to the midrange Nice and smooth LR2 to the tweeter How about that It has to be said that drivers need careful alignment to render this performance i e stepped baffle Driver phase integration Nice and smooth Impedance Flat 4 2 ohms minimum at 80 Hz and mostly 5 6 ohms above and below Not bad for a 3 way made from 8 ohms drivers Even modest valve amps should be able to cope with this back to the real world After some fine tuning this appears to do the trick In short The bass The DeltaLite needs a baffle step compensation circuit to decrease sensitivity and equalize the low end 8 2 mH shunted by 5 ohms does the trick and we re down in the 95 dB range The DeltaLite 2515 really does some 98 99 dB as stated in driver s spec Generally I find Eminence data not too far from reality and even frequency response from this 15 driver is excellent After the baffle step compensation circuit we have a standard 2nd order low pass section at around 150 175 Hz I my listening room I have a 1 0 ohm resistor 10 watt in series with the bass section to better match room acoustics Two 15 bass drivers have no problem loading a 25 sqm listening space The midrange We need a high pass section on the midrange Based on measurements it turned out 80 90 uF could do the job Next the impedance flattening circuit was tried R L C 2051 and didn t make any noticeable difference so it was left out The 8008 driver has a little rise above 1 kHz due to the wide baffle thus a 1 mH for low pass section The rest is very close to the crossover used for TQWT and DTQWT The tweeter section Identical to TQWT and DTQWT crossover All in all more manageable compared to the no compromise 1 crossover There is one serious issue here The quality of the 88 uF to the midrange Initially I ran 82 uF standard polyprop caps bypassed by 1 uF Superior Z cap After several hours of listening I pooled all my Superior Z caps to make 84 uF and replaced the standard caps Sorry to say it s night and day Any standard polyprop sounds compressed compared to the Superior Z combo Eight times 22 uF quality caps don t come for nothing but once we ve heard the super caps vs standard polyprops it s very clear there s no free lunch here I m sure I ll have the question on active crossover for bass and mid and with this construction I have no reservations Maintain the passive baffle step compensation circuit to the bass 8 2 mH bypassed by 5 ohms and target a 2nd order slope around 175 Hz Next Target 1st order slope to 8008 TW034 combo at the same point of crossover and finetune by measurements to flat response I don t think an electronic solution can be implemented properly without measurements Considering the sensitivity of the OBL 11 95 dB there is hardly a rationale for active filtering and an additional power amp The cost will be the same or more compared to 8 x 22 uF Superior Z caps Anything from 80 90 uF is fine for midrange series capacitor Go to crossover layout The Baffle Back to index Go to OBL 11 Baffle Construction Page From outer appearance my baffles may resemble the SFBs but rather than making a sandwich from thin plywood filled with sand
    http://www.troelsgravesen.dk/OBL11.htm (2013-02-26)

  • Jenzen-Diamond
    The diamonds are neither hard nor silky they are a significant step towards more fidelity Cymbals bells triangles btw are a delight and frankly I never thought a dome tweeter could make this much impact because I ve tried a lot over the years It not only delivers effortless treble it improves the response from the midrange driver or so it is felt as the midrange is obviously doing the same as before but the ear cannot for sure determine where the transition is If mid tweeter integration ever meant something this is it Another thing that was surprising was listening a low levels I thought the diamonds would fade turning down the volume Not so clarity and transparency goes all the way down and tells the story of generally low loss drivers I have second hand two dollar LPs I bought out of curiosity and never heard more than once either because the recording wasn t that good or the music not really inspiring The Jenzen diamonds require a second listen and pearls are found from time to time Based on efficiency related to moving mass radiating area and BL factor the diamonds are nothing special yet delivers an unprecedented transient response which took me by surprise These diamonds are not particularly fast based on measuring data yet supercedes anything I ve heard so far The quality of the bass from the Audio Technology 10 sandwich bass driver in this transmission line cabinet is the best I ve ever heard from a medium sensitivity bass driver Articulate precise and responsive and even so at low levels I could go on but before even finishing listening to more music the inevitable question arise What s next You may object that this isn t the time to think what s next when what I have described sounds like aural nirvana It is the best I ve ever had in my room and it is going to be a reference speaker but the Jenzen cabs are a bit too big for our living room So can all this be preserved in a smaller enclosure making less impact on room decor Time will tell I had a Jenzen Accu four way on the drawing board with the Accuton 2 dome bridging the C173 and C30 but now I m not so sure The added cabinet and crossover complexity may not pay off and I would get less of the diamonds having a point of crossover in the 4 5 kHz region Right now I can t get enough of the diamonds and 2 Accuton diamonds are way out of reach There s nothing like a new tool that allows you to learn new things and create new standards All things written about the Jenzen Accus go for this speaker as well and I shall not repeat myself here Please read the Accu file and find out what I mean Final front panels under construction These will have more stealth appearance compared to first
    http://www.troelsgravesen.dk/Jenzen-D.htm (2013-02-26)