Speakers' Corner 01 March 2010 It's
been a long and cold winter and people in
Scandinavia and the Northern Europe - based on response
to my website - have spent a lot of time in the workshops
building speakers. Apparently there's no economic
recession when it comes to diy speakers. What else has been going on in my workshop these recent months? From the most recent files, Study on stepped baffles with little impact on tweeter performance., Siri's Killer Note, it may shine through I've taken a deep look in the practicalities of making 1st order Butterworth filters. Actually it seems clear that it's easier to make a 3-way 1st order crossover compared to a 2-way. Nevertheless, the last month I've been listening to eight crossover versions of a small "6+1" monitor. In reality this can go on forever trying to improve phase integration and frequency response from changing the stepped baffle, tilt of cabinet and subsequent crossover mods. What seems mandatory is proper phase integration between 1-10 kHz. Reversing tweeter polarity we need a decent suck-out between these two extremes and things appear to start sounding right. One octave below and above point of crossover isn't quite enough. My best guess at this stage is 1½ octave and we're safe. It either takes drivers with exceptional linearity - or a lot of equalisation via notch filters. Don't be frightened by 3 notch filters in shaping the roll-off of the midbass. Fortunately these are in parallel to the driver and sometimes do very little - but may improve phase integration considerably. What also seems clear is that amplitude irregularities (linear distortion) are much less noticeable when drivers are driven from a 1st order Butterworth filter. Well in accordance with the findings of Vandersteen, et al. Currently
I have this monitor in our living room run by the
JungSon and I like what I hear. I've listened to more
classical music from these speakers than I use to do.
Audience clapping - as always a great tool for evaluation
of speakers - are improved compared to high-order
filters. Clapping sounds darker with reduced impulse
distortion. Sibilance is much more tolerable, which is
great! Sibilance is a much too common problem due to poor
stage microphones and singers having a much to close
relationship to their mics. Next to this any sound of
acoustic instruments seems improved and more natural with
regard to timbre. Oh yes, I've read Michael Fremer's review of Vandersteen Model 7 speaker (Stereophile, March 2010). The ultimate impulse and phase coherent speaker system with proprietory cones made from balsa wood and carbon fiber. I've been looking forward to this. Fremer says he could live happily ever after with this (45,000 USD) speaker system and only reservation is the lack of visceral slam from ochestral climaxes. No wonder, this speaker claims 85 dB sensitivity and Atkinson measures 84 dB. All this work and 84 dB sensitivity...Vandersteen must be really keen on keeping size small and bass extension deep. 01 Dec 2009 It's been two months since last speaker's corner and November was indeed a busy month of diy. Many, many mails with no particular theme, rather comments and questions regarding a wide range of constructions found on this website. Quite a few people have visited the 10C77 pre-study and the PRELUDE is up and running although not yet with the final midrange. The target sensitivity of the midrange has been handed over to Per Skaaning of AudioTechnology and hopefully I'll have the drivers before Christmas. In the meantime I can sand and oil the cabs. Regarding frd and zrd files for speaker simulation: I do not provide these files from my LspCAD library. I have done a few times and people sometimes get all sorts of funny results and I do not have time to discuss how to use the files correctly. Sorry! Looking at website statistics is always interesting and I'm surprised how many hits the L100 and Spendor BC1 have. The BC1 scores high month after month and apparently holds a huge audience seeking information. I have two front panels waiting for a BC1 refurbishing, which will probably turn BC1 lovers away in disgust, because I'll transform the cabs into solid, well-braces cabs, flush mount the drivers and make a new crossover.... How about that? I took the speakers to my livingroom recently and what a sluggish and un-precise bass performance. We should be able to do a little better here. For all the thin-walled cabinet is supposed to do, don't forget it also meant low weight, reduced production cost and not least, reduced transport costs. I don't think we should be too blue-eyed here.
Asking for contribution to the
website was certainly not something I'd ever
considered until my webhotel gave me three options:
Reduce file size/upgrade to superpack/get lost! This is a
little more polite than last time where my former
webhotel just shut down my website without any warning.
Who are these people running webhotels? Robots?
Apparently they don't have names and they like to express
themselves in one-liners. I mean, I have no interest in
annoying these people and something like "Mr.
Gravesen, your traffic is exceeding so and so many
GB/month and you need to udgrade you hotel." No
problem! Of coarse I will. 11 Oct 2009 Making a crossover and connecting
the drivers right may not be as easy as it seems from
a quick look at the crossover schematics. I steady flow
of emails from first-time diy'ers suggest that reading
this file may be a good idea: the
importance of wiring crossovers correctly. I'm pleased and proud to have the Audio Technology 2-way back again on the website, now with the SWANS RT2H-A planar tweeter in replacement of the Raidho planar tweeter. Read here about the new AT-SW. And I've been visiting Audio Technology to pick up the 10C77-25-10-KAP 10" bass drivers with the new sandwich cones. Initial measurements suggest a 45-55 liter cabinet volume and a decent response down to 30 Hz. The sensitivity of the driver suggests a system sensitivity of 90 dB being possible. A pre-study has been done to gather information on performance before cutting sheets: 10C77.htm
These bass drivers are some chunky beasts weighing more than 8 kgs each. Measurements suggest a flat response up to 1.5-2 kHz and for fun I tried modelling a two-way system with a point of crossover at 800 Hz. No problem at all. Next I'll do some measurements to compare the drivers with ScanSpeak 26W/8861T00 and SEAS W26FX002. 11 Sept 2009 In June's Speaker Corner I made some
comments on boring "6 +1 inch" speakers and
I won't change a word of what I wrote. However, a recent
standmount speaker project incorporating an Audio
Technology Flex Unit 6A77-25-10-KASD (4 ohms version) got
me exited again on small speakers. This driver features a
generous 3" voice coil former being a composite of
both aluminium and kapton. Now, having some 174 square
centimeter membrane area, this driver falls well in
between a 6 inch and an 8 inch driver but I think it will
be hard to find any other 8" driver that can truly
match this driver when it comes to power handling,
dynamics and resolution. It's phenomenally good and
should you ever wonder if high-priced raw speakers are
worth while, not to forget premium crossover components,
this may be the one can demonstrate that proper design
pays off. A lot of diy-projects have been through the workshop for crossovers the last couple of months and there's been little time for my own fun. Scanning the web I came across Wilson Audio's website again and couldn't help stopping at the intro pic showing the Alexandria speaker. A stunning sculpture resembling a heavy-bellied person bending over and - maybe thinking of what the future will bring? Next the new Sasha being a very clever design up-lift from the never-dying Watt/Puppy. I find the Sasha design so good I'll clone without blushing at all. It has a stealth quality I find appealing. Rather than 2 x 8" drivers, I'll use an Audio Technology 10C77 (sandwich cone) driver for bass in a TL design and have Per Skaaning help me designing a 6" mid-driver than can match the 10C without any series resistors. Winter 2010 project.
Up-dating the ATR and ATR25 constructions for the new SWANS planar tweeter obviously made we wonder if this high-sensitivity planar was suitable for the DTQWT design. For a couple of months I had the set-up running thinking it was work done! It took an old friend to tell me this really wasn't as good as the old one. Being your own hardest critic is not always easy. Thus the DTQWT goes on as-is and is my reference speaker. I have made drawings for 1.5 meter tall version for 10" and 12" bass drivers, but when they'll see light is hard to tell. Woodwork takes time. And no, I have
not tried the RAAL ribbon and I won't. I
think I have a mail every second day if I have tried this
ribbon. I've tried a lot of alu ribbons and generally
find them suitable for metal cones and some polyprop
cones as well. For paper pulp cones - generally not a
good match to my hearing. Planars usually goes well with
polyprop and sometimes (heavily) coated paper. Alu domes
for alu midbass drivers and sometimes polyprop or coated
paper. Good softdomes goes with everything without always
making the perfect match. Very little experience
with ceramic domes. 08 July 2009 View/hear the lecture on "This is Your Brain on Music" by Daniel J. Levitin at Microsoft facility.
16 June 2009 Setting up the Summer-09 open baffle project, the OB9, from JA8008/TW034 + Eminence 15" bass drivers made me realise how utterly boring conventional speakers can be. How can I ever make a 6" + 1" midbass-dome-thing again? I will be doing it, actually a lot of them, but it takes a little time to recover and see the fun in small, boxy sounding and un-dynamic speakers again. Most speakers simply cannot even come close to rendering the true dynamics of an upright bass the way a 15" driver on an e.g. open baffle can do. Small speakers may to some extent be emotional engaging, but only when we hear a really large bass driver on an open baffle - or in a horn - do we also get the physical engaging sound we're longing for. We finally get the "punch and the drama"! The featherlight kick in the stomach - and we're looking at the bass-drivers to see if the cones are thinking of leaving the chassis' - and they're certainly not. They barely move at all. Magic! With a total of 1700 square centimetres membrane area, things start to work out. No wonder some 130-150 cm^2 from a single 6" driver can't do much. Even a 2½-way system from 6" drivers won't count for more than a total of 500-600 square centimetres. A rather big ScanSpeak construction has been launched recently, the Jensen, from 10" ScanSpeak bass driver, well-known 18W/8531-G00 for mid - and the 18W has never sounded better - relieved of pumping air and at the same time trying to cope with upper mid and lower treble. Goes well at modest sound levels, but here we render the full potential of this fine driver. Last but not least I was pleased to get first-hand experience with the 9900 tweeter. It's great, the best Revelator I think and on level with the excellent SEAS T29 domes. The DTQWT is doing well and a lot of kits
have been sold and I'm looking forward to receiving
comments and pics from the buyers. I've had a number of
visitors for hearing the DTQWT and the response has been
good. Whatever people bring of CDs and LPs, the DTQWT
will play it all. From classical music to the most
outrageous heavy metal stuff. My new line stage project, 5687, is coming to an end, and the hum-war is on hold from the final version. The DTQWT system is not totally free of hum yet, but now it's one of the Audio Mirror amps that needs some attention. The blessing of home-made electronics... I feel urged to comment on the
quality of some recent Verve vinyl pressings from
the US. Diana Krall, Anthony Wilson, etc. 180-200 grams
"super" pressings and the vinyl surface is
crap. Visually blurred and sometime so noisy it's looks
like it's been taken hot from the mold and thrown into
its sleeve. How come? Who's pressing these LPs? Has
anyone experienced the same thing? 08 April 2009 It's been a busy winter with quite a
range of SEAS constructions and Scanspeak
crossover for speakers coming in from diy people here in
Denmark. Check ScanSpeak
constructions and SEAS
constructions on intro page. These early days of April the temperature has risen to some 15 deg. C and it's time for spending time outdoor, digging the vegetable garden and getting rid of the garden debris from five long winter months. Speakerwork will slow down for some months. Not least due to amplifier building although an open baffle speaker is on the to-do list; the summer fun-project, like the OB7. This time OB9 from 8008/TW034 and a 15 inch bass driver. Identifying bottlenecks in our systems is a
never ending exercise. Few years a go I had a guy
visiting with all his silver interconnects and silver
speaker cables and we weren't able to hear any difference
comparing these to my rather mixed blessing of cables.
Not at all. The set-up at that time was a modded Rotel CD
player, Audio Research SP16L line stage and Copland
CTA505 power amp. I don't recall the speakers at that
time. Once and a while we may be fortunate borrowing a piece of gear that may identify a true bottleneck in our system. The 5687 line stage with output transformers was such a piece of equipment, originating from diyhifisupply in HongKong as the TRAM w.o.t. line stage. Product is discontinued, probably due to cost of output transformers - or maybe hum problems, because the original TRAM has some serious hum problems only realised when you run real high-efficiency speakers. Cloning the TRAM isn't particularly difficult, but getting rid of the hum turned out to be serious trouble. So much trouble that I'm rebuilding the line stage with a separate power supply unit. This line stage is so good I'm ready to go all the way and I have even ordered a new power supply trafo to get all the secondary tabs I want. *Having success with
the silver interconnects, I thought it was time to try
out that silver foil for speaker cables I've had on the
shelf much too long. So, the foil was wrapped in paper
(painters' tape) and I ran bi-wiring to the DTQWT having
silver plated copper in teflon for the bass drivers. Things like the above certainly need repetition! So, next day I installed the bi-wiring system again and it wasn't quite as bad as yesterday - late evening - maybe I was tired, but something certainly wasn't right. Midrange/treble integration still didn't work. So I ran the DTQWT from the silver foil alone and now things started to develop in the direction I had expected. Silver does something to the midrange in particular. It sounds less lush, less coloured, less smeared. It sounds very cool and clean and you wonder whether you would voice your speakers differently had they been developed with silver wires, etc. How about a DTQWT set-up with silver wires, Mundorf Silver/Gold caps, Jantzen Audio Silver Coils, graphite resistors and - - dream on. This would triple the cost of the kit. Anyway, foil wires are trouble. Fragile, trouble when you need cleaning around the speakers, low WAF, etc. What I really had in mind was making a multistrand silver wire from e.g. 12 x 0.4 mm silver wire = 1.5 mm^2. I only need 2.5 meters of speaker cable + 1.25 meter for internal cabling in the DTQWTs, thus (4x12) x 3.75 meters = 180 meters of wire = 235 grams silver = 1400 DKK (250 USD) from my local supplier. Not too bad after all. Let's see. 15 February 2009 Yesterday was Saturday and with the lady of
the house gone shopping, it was time for some serious
kick-butt, rock'n roll. Front end was Garrard 401 + LINN
ITTOK LV II arm + Dyna XX2 mkII cartridge/Transcendent
RIAA with Mundorfs/TRAM w.o.t. line
stage (DiyHiFiSupply)/modded Audio Mirror 6AS7
mono-blocks/Rotel RB981 for bass drivers in DTQWT
speakers. The TRAM line stage has out-put transformers
(w.o.t. = with output transformers) and can easily driver
two power amps. Which makes me think of a visitor I recently had, bringing in a 20,000 DKK (~3,500 US $) TentLab CD player to compare with my slightly modded Shanling CD-T80 (I paid 650 US $ for this player from Hong Kong). Playing a wide range of CDs, we really weren't able to hear any difference at all. Now, my visitor also brought a CD which I happen to have on vinyl (Eva Cassidy) and this called for some A-B testing of vinyl vs. CD. Visitor was pretty shocked from the difference. Needless to say the CD sounded flat and congested with poor dynamics and transparency compared to what the XX2 cartridge could pick up from the vinyl grooves. Now, CDs can be good and bad. I have a (very few) excellent CDs where everything seems to have been done right to get as much information through the media as possible, but generally most of the CDs I have on my shelves are poor. In Stereophile, Feb-09, you can read about a demonstration at DIY Burning Amp Festival, where " - Jan played back samples of the same song released over a span of several decades. Each one sounded worse, more compressed, than the last. It was so shocking that it made people angry". No wonder! Recent Months have brought a range of new speaker constructions : SP44, CNO-mkII, CNO-T25, Maya (SEAS CA18RNX/T25C003) and CNO-25 (CNO 2½-way), and I guess I'll take a break from SEAS constructions after this. I need to put together some plug'n play kits to finance new projects. And I'll be cloning the TRAM line stage and have started sourcing components. The project I'm looking forward to the most is an open baffle construction with the JA8008/TW034 drivers and some 15" at bottom. This OB should as close as possible look like the old Wharfedale SFB. I just love that design. 28 December 2008 Economic recession or not, people are building speakers like crazy these dark winter evenings and weekends - at least on the Northern Hemisphere - and coming home from work, I find my mailbox full. It takes an hour or so every evening and please forgive my short replies. Usually the Christmas holidays are very quiet with mails, so time for some writing and a few experiments. There are a lot of speakers in pipeline the
coming winter months: CNO mkII, CNO-T25 (T25C003 tweeter)
and a CNO-25 (2½-way CNO). I have reworked my test cabs
for these constructions. A Happy New Year to all diy'ers visiting my website! 07 November 2008 Do you have the same experience as I
that sometimes your hifi system sounds crap and sometimes
just sounds great? Nothing in the system has been changed
and yet there are good days and there are bad days. I'm tired after a normal working day filled with
mails that have to answered, meetings I have to attend,
talk with my colleagues, driving my car and paying
attention to heavy traffic, watching the news and the
Obama election, etc., etc. The everyday contains an
enormous amount of information that has to taken in
and/or taken care of - and after all this I'm really not
in the mood to be fully aware of subtle differences in
the performance of hifi components. Good or bad is
sometimes a matter of state of mind and not how the
system is performing. Loudspeakers are the most troublesome
components in our system. We not only listen to our
speakers, we listen to our speakers and the
room, and not only the speakers in our room, but the way
the speakers are placed in our rooms. If you happen to have a listening
room of e.g. 20-30 square meters of reasonable
dimensions, square is often worst, take a day off and
move your system around including all your furniture. Try
every possible positioning of your speakers and hear what
happens. If possible try your system in a smaller room
and a bigger room too. Try the bedroom also! At least
here we may have some fabrics. Now, how does it all
sound? One room better than the other? One position
better than the other? By chance I came about this website:
http://www.stereodan.com/stereo.htm 19 September 2008 "Could I use 2 x SS 18W/16831G00
in replacement of the single bass driver in the SP38/13 construction and
use the same crossover?". "Could you change the page
set-up in your files because I have an
old monitor and 800 x 600 pixel setup?" Now, that's
a new one! I have asked around and I can't find anyone
running this format anymore. I have a standard
laptop/14" screen and usually make my tables
1000-1100 pixel width. I use tables because it allows me
making the page layout I want (from my stoneage Frontpage
version, I admit). I'm not particularly interested in
computers (- but I love what they can do) and usually
stick to my old software if it works well. There are
about 250 pages on my website and changing the format
would be an enormous task. So, "sorry, won't". The poor devil buying my TJL3Ws hadn't checked with his spouse in advance and all hell broke loose when the speakers were installed in their livingroom. Wood finish didn't fit furniture veneer and to avoid sudden divorce, the speakers were wrapped in white plastic foil.... All that nice woodwork - for Heaven's sake! Point is: Don't forget to check with your loved ones before engaging in new speakers! More WAF issues: I had a mail from a guy showing some of my constructions to his spouse to hear her opinion about possible designs. Now that's the way to do it! Her response was: "All these speakers look like coffins! Horrible!" She has a point. Most floorstanders may look more or less like upright coffins. We only need some flowers to bury our addiction to music! The single construction she did like was the Acapella. So, I asked my wife the same question and she was in favour of the Acapella too, comparing all the speakers she'd been living with over the years. Hmm... I always liked these cabs better than anything else I've made, but it will be tough squeezing the DTQWT into an Acapella design!
Thinking of coffins, these come in all
shapes and sizes and maybe this would be an options for
those engaging in speaker-building for the first time. As
can be seen above someone already got the idea. I have
seen speakers looking more terrible than these. Some
coffins come fairly cheap. Add braces and bitumen pads
and a pair of 12-15" bass drivers and I'm sure you
could impress you bodies - but I guess it's for
"singles only". To keep green-house gasses down
you can even buy coffins made from recycled materials
degrading without environmental damage. Fully RoHS
compliant! - anyway..... Magazines:
I suggest reading the whole article at
Stereophile's website once published: http://www.stereophile.com/thefifthelement/ An extensive test of coupling
capacitors has been performed on my 300B integrated amp and this is a
never-ending exercise. Mundorf silver/gold/PP and VCaps
are the winners here, but read for yourself.
Last but not least: Some bedtime reading on the state of hifi (Gordon Holt/1991 and Art Dudley/2004). Download here. 23 August 2008 Finally: The launch of the DTQWTs. It's been a long, long journey and hifi - to me - has never been more exiting. The DTQWTs are doing what I want my speakers to do: A huge soundstage, a midrange delivering the presence and detail I want without being harsh or aggressive, deep bass delivering the punch and drama we want from reproduced music and last but not least: High sensitivity allowing low-wattage triode amps to be used. With these speakers I can easily evaluate subtle differences in the quality of components used in my amplifiers. My Audio Mirror 6AS7 SET mono-blocks and the 300B SET amp are already revealing interesting - and different - ways of amplifying source material and soon a Transcendent T16 OTL will be finished and tell if omitting out-put transformers really is as important as Bruce Rosenblit says. 28 July 2008 The final DTQWT cabs are shaping up and only needs the final lacquer before finished. The DTQWTs pretty much do what I want my speakers to do and I might just quit speaker building here. My bank account to some extent reflects this as I spend more money on vinyl and less on new drivers. That's how it should be! Well, a few more amps are on my wishlist and besides a diy 300B SET under construction, a Transcendent T16 OTL has arrived. The DTQWTs are sensitive and they project a big, wide and transparent soundstage and allow me to use all sorts of amplifiers, but I do rush to say I do not recommend 2 wpc SET amps. No matter what loudspeaker and amplifier producers may claim, there are limits. I do recommend 6-8 watts minimum. Often we see that 2 wpc amp producers may claim their products suitable for minimum 90 dB speakers, but be cautious, it very much depends. And speaker producers may claim their 90 dB speakers suitable for 5-10 watt amps. Again, be cautious. I recently made a crossover for a large 3-way speaker (ScanSpeak drivers) and I ran it from a 6 wpc SET amp and it sounded great - but indeed not very loud. If we run 2 wpc SET amps we need humongous horns with extremely light-weight paper cone drivers to render a true presentation of bass fundamentals. Anyway, there will be more speaker constructions in the future and more 2-way/6"+1" kits and some 3-way classic kits from ScanSpeak 21W/8555-01 + mid + 8513 tweeter. I have a range of mid drivers that look very promising from simulation, i.e. simple 2nd order filters and flat impedance curves. The D2010/8513 is special in this context and seems just made for 3-ways with a relatively high point of crossover between mid and tweeter. Modern 1" tweeters are often designed to extent the lower end - to make two-ways - and some of the 3-way simulations I have made got into serious trouble when replacing the 8513/OWI with e.g. SEAS 27TFFC, SS 9500, etc. These 1" dome tweeter often takes 3rd or 4th order filter to perform from e.g. 3.5 kHz in a 3-way set-up. The EKTA might do well with the 8513 tweeter from a simple 2nd order filter at 3.8 kHz - but I'm afraid people wouldn't believe it. The summer sale quickly ran out of 2-way kits and I need a break before launching more. Selling a kit requires quite some hours of actually making the kit with presentations, etc., and often takes 10-20 mails before it's actually sold, not to forget packing the kit to ensure safe transport. But it's also fun hearing from people all over the globe and exchanging views on speakers building. One of my summer holidays has been spent reading
reviews - speaker reviews - and gosh, are reviewers and
manufacturers one big family! I'm amazed by how reviewers
manage to write 3-4 pages on a new speaker that is
slightly different from the old model. We are told it's a
significant improved product, yet in no way does it
diminish the qualities of the old product. So, we're all
happy! A few times I may actually know first hand the new
drivers - don't ask how - and know the changes were made
to cut production costs and increase profit. I wouldn't
never blame manufacturers for doing so, but the way
reviewers are able to handle this is a matter of
linguistic artistry. Bravo! Buying on eBay has been low for
the past months, but a single Wharfedale Super 8
FS/AL was found - and bought. And it's one of the
better drivers from the Fifties. Much better than the
terrible Super 8/RS/DD. As expected, not
much of the foam surround had survived transport but I
managed to find some fine felt material and have made a
new surround. What I don't get from these Wharfedale
drivers of the Fifties and Sixties is the acoustically
transparent outer surrounds. Why? Even some of the later
fabric surrounds were acoustically transparent. It causes
serious trouble in the midrange. It doesn't fit with the
response graphs found in Briggs' book. Any ideas? 17 May 2008 Launching a sale takes a deep, deep
breath! Space and finance is the reason behind this
and I know it takes tons of mails back and forth before
diy-people decide to buy anything. But here we go! Take a
look at the '08 Summer
Sale' if you might be thinking about the
following items: Acapella
NEXT, TJL3W, Compact Studio Monitor Kit, JBL L100 matched
drivers + crossover KIT, ARC SP16L preamp, TubeBox phono
stage, Rega RB300/Incognito tonearm and W11XT speakers. 7 May, 2008 It's springtime and really not a time for doing loudspeakers, but you can always gather components for the next project while digging the vegetable garden and mowing the lawn. And so I do - like seen on the photos below. 10" bass drivers, wax coils, super caps, cables in teflon wrap, low-ohmic C-coils, new cable plugs, gold plated soldering tags, etc. All meant for the DTQWT project, i.e. Double-Tapered-Quarter-Wave-Tube. The DTQWT is the JA8008/TW034 kit with two 10"
drivers on the rear panel loading a common center horn
together with the front driver. No big deal really, but
finding the right bass drivers and the right dimensions
of the horn has taken time. Some 5 different 10"
drivers have been tested and two candidates seem to do
the job well. One is Beyma 10LW30N, rather expensive but
with excellent build quality. The other is a 10"
Pioneer driver derived from the US. This one is cheap and
does a great job too - at a fraction of the cost of the
Beyma drivers. My system has been through a lot of up-grades lately and this has urged me to use the very best I can afford for the DTQWT. In addition to the components seen above I'm doing homemade silver foil speaker cables and graphite resistors for the crossover. I'm not sure all these measures will contribute equally to the good sonics, but for the benefit of the doubt - and to gain experience. Gathering components also includes bits and pieces for a 8 wpc 300B SET amp. I need a really low-wattage amp for reference with the MAE now back in Norway. The 300B amp is based on the Oliver design shown here. 20 March, 2008 I've bought a new phono cartridge! I never invested
heavily in these things and I was pretty happy with my
Dynavector 10x5 until a wire from one of the coils broke
and these tiny wires are way too thin for repair (I
tried). So, a deep pocket dive and a Dyna DV20X was in place. 400
£ for a cartridge was serious money I thought, but it
provided one of these rare occasions where you - once
more - have to go through a lot of your vinyl collection
to hear what you've missed over the years. Self-pity is a
really bad thing, but it came close and it kept me
wondering what I would get for 800 £ or maybe even 1600
£. Better start saving for that next step. The ATR25 was finished early March - took a long time to get the cabs finished - and these are "disturbing" speakers. Disturbing because they do a lot of things better than any other speaker I have. Still don't beat my JA8008/TW034 - a matter of taste and WAF - but at half the size - and twice the cost - they take midrange clarity and treble quality to new levels. No domes can do what these planars can do, that's for sure. My 20 wpc SET mono blocks have no trouble driving these transmission lines and I'm having good times in front of these speakers. Despite high level of transparency, they handle all musical genres equally gracefully. They don't make poor recordings sound worse. Low distortion is the key word. Right now the JBL L100 Recreation is on the workshop bench. Cabs are finished and I need to add damping, install crossovers and drivers. I think I've spoiled the L100 kit as much as possible and I'm looking forward to hear if it all makes a significant improvement compared to the originals. I think it will. The original box is rather resonant and having the 12" bass driver handling most of the midrange, there just gotta be serious improvement gained from a well damped and braced cabinet. On my way home from work today I picked up some 5 square metres of 19 mm DMF (pre-cut to some extent) for my double TQWT, the next JA8008/TW034 system. Have collected 10" bass drivers over the last half year and I'm expecting to have some 5 pairs for test. Two pairs of Beyma drivers, two pairs of SEAS drivers and I'm waiting for the last pair of 10" drivers from the US. You can find the principal "DTQWT" design here and here: Two conical horns feeding a common center horn mouth. The High-End Kit for Beginners is ready for sale.
NEW: High-End
Kit ATR25 transmissionline is ready for sale. The JA8008/TW034 is ready for sale.
12 January 2008 The Acapella NEXTs are up and running: This project started like: "Well, I have the cabs and only need a bass driver" and turned out to one of the most rewarding projects I've made. You never can tell. There's a long list of projects planned for 2008. After the Acapella NEXT, the ATR 2½-way is next. View ATR-2-way here. Initial test set-up will be a bass-reflex design and initial listening test from a quick simulated crossover is promising. The final cabs will probably be a classic transmission line with the same front panel dimensions, allowing the crossover to be the same for both versions. When
the ATR-2½-way is finished, the JA8008 55-litre
bass-reflex is scheduled. The project has been on hold
for some time as initial tests in a classic 36 x 80 x 28
cm (W x H x D) cabinet didn't sound right. The crossover
was easy, measurements were good, but the sound was just
too forward. Too much midrange despite an overall flat
response. My main suspicion is the width of the front
panel and a more narrow design will be tried. Actually
similar to what can be seen on the sketch shown at the JA8008 page. Next project is something I'm really looking forward to do: A "W26-Classic" 3-way from SEAS W26FX002 + M15CH002 + T29CF001. Possibly the middriver is going on top in a separate semi-open cabinet. Having the mid on top is seen before in older KEF & B&W speakers. However, my initial inspiration came from the Spendor SP100 and Naim DBL. We'll see.
The "W26-Classic" cabs will also allow a test set-up of my JBL L100 drivers. Modelling the 123A bass driver in a 65 litre cab looks promising. Did I say 2008? I also look at my
Spendor BC1 speakers from time to time and I have 22 mm
plywood sheets on the shelf for new front panels... and
I've had a pair of "vintage" SEAS EXCEL
W21EX001 drivers for a reasonable price. These drivers
have a hard paper cone and performs exceptionally well
although sensitivity is some 3-4 dB lower than promised
from the old SEAS data. An "EXCEL VINTAGE" from
W21EX001/W11CY001/tweeter could be interesting. Speaker Talk 9 December 2007 SEAS has got a
new website and it's certainly better than before. And
they are about to launch a new "alnico-whizzer"
driver - with rubber surround...Hmm... Have they
heard the cry from the SET people right? While the Norwegians seem fit for
fight, I'm wondering how things are in Videbaek town, not
too distant from where I live. Apparently people are
fleeing the castle of Vifa/ScanSpeak and have started new
companies, e.g. SB Acoustics and GAMUT, based on former dst
employees. I'm sorry to say that whenever you guys
"over there" take over smaller companies
"over here", things seem to rapidly deteriorate
- from our perspective. RCF, Audax and now
Vifa/Peerless/ScanSpeak are examples. I'm wondering if
the Tymphany air-pump can compensate for the departure of
some key figures in the former dst
organisation. This is - to my eyes - the only radical new
product from the Tymphany company for a long time. This Month's Speaker Talk was meant to deal
with a few reflections on how differently we perceive
sound. Not a new topic, but I still wonder sometimes how
people claim aural nirvana from speakers I dislike - and
know first hand - like the vintage Philips 9710. I had a
mail from a studio engineer, seriously suggesting this
driver as a great tool for monitoring. I don't get it. "I have found myself 100% captured by listening to 12 x
17 cm full range drivers mounted in cardboard boxes with
an open back. I have also found myself 100% involved by
listening to 40 cm coaxial drivers. Every speaker has
something to say! The beauty of the sound of some small
driver may weigh up the power of some big driver. On the
other hand, the sheer power and authority of the big
driver may please me more than the delicate sound of the
small ones. It depends on my mood and on the sort of
musical material. I have had lengthy discussions with a
former Klangfilm speaker engineer and we have both agreed
that the whole matter depends very much on proportion and
on harmonic and well balanced tonality. If you listen to
a 20 cm full range driver you will obviously not hear the
authentic impact of a full scale big orchestra. But
– provided it is a “good” driver –
you will hear the orchestra as an entire phenomenon. On a
smaller scale!" In line with these words, I recommend
reading an article by Art Dudley (Stereophile, Nov-07,
page 41) on a speaker system from Aurum Acoustics: |
