Horns and Triodes...?
Greg, I understand the Tractrix front-loaded horn arrangement just fine, and there are some things like that already out there using Lowthers, like the Oris 150. However, most designs like that have a box loading of the rear of the Lowther, and I was most interested that your design did not load the cone in the normal manner. I expected the rear radiations to play into this equation at some point, and was interested in your comments about that. I think the idea of an open baffle Lowther is interesting. It sounds to me like you ended up with some sort of "aperiodic" loading design. To Paul: The horn contour is designed to have a "lower cutoff frequency" which is defined by the length and mouth size of the horn. At this "lower cutoff frequency" the bass sounds are no longer amplified by the horn, and the efficiency drops off correspondingly, like an acoustical filter. |
I am crying. I think I will never be able to take a hack into your project, unless I have really idiot proof explanation and some decent diagrams, but man, does your set up sound like something out of a futuristic movie. I luv it! If you can, try to make some diagrams of it and also pics. "youngwon gidarilso iqkeso",I can wait forever until you have this! PAUL |
Hi Tom, Paul- Geez, I don't have the exact measurements handy and no pics yet (I'm a bit of a wet rag -- sorry). The whole construction is on an open baffle: The Lowther is wearing the wooden phase-plug. The tractrix's flare frequency was calculated for 120Hz; mouth diametre just under 1m; throat is just larger than the Lowther's cone+suspension; horn's length under ~1m; presently (and cheapo-ly) the horn is made out of cardboard & I don't remember how many-sided it is (12 probably). We plan on using suitably treated (i.e. "good-looking") plywood strips for the final, WAF approved, version... The back of the cone is damped -- good point Tom. In fact, we tried it open baffle (hmmm), covered the lowther with some material (admittedly better), finally made a small rectangular box, damped the spider, no box damping (best - amazingly!). The point is we were getting interfering reflections from the Lowther's back on the open baffle scheme (we *were* close to the back wall, after all -- about 1m away only) Now to the subwoof. Quite simply, there were 15" Beyma 400's lying around. With a total q in the upper 0,2's, these were unlikely candidates... but then, they were immediately and freely available for the experiment. Xmax looked OK at ~7mm. We attached these to the baffle (~65cm width) -- one per side. We attached two 50cm sides to the baffle -- more for structural reasons than anything else and to simulate an H woof (open baffle). Amazingly, this Beyma/Lowther combo works! The beyma is perhaps not the most versatile transducer around but "speed"/(phase) discrepancies are not subjectively perceptible. The B's BL factor of ~22 and a reasonable mms (just over 100gr, if I remember) probably help here. However, marrying the dba's (horn w/ the woof) was not that easy. Putting this together: We matched ("equalised") the Beyma/P-L combo's db level at ~60 Hz to the horn's ~130Hz (the beymas were losing ~7db @60Hz vs 120Hz) & "flattened" it with the low-pass. As you expect, the 300B drives the lowthers x-overless. Subwoof: we are taking output from the 300B, feeding that into a passive low-pass, then into an old 400W/Ch Phase Linear (P-L; for the young, that's an old manufacturer:)) which drives the Beyma coils directly. Strangely, the passive filter sounds better than an active one we tried. Final task: align acoustic centres (i.e., bring the woofs forward). This will have to wait until we finalise the woofer units. If finances allow, the supravox 400-EXC with the electromagnet field coil. Makes for a very versatile driver (basically, one can adjust vas & qes->qts). Also, at $7-800 apop, it's an expensive driver. Is dreaming allowed? TWO Supravox 400 per side in a W config... A final point-- my personal contribution to this construction is practically nill; I just insisted on trying open-baffle and supported (enthousiastically) front-loading the Lowthers. This friend calculated the exponential (tractrix) horn by himself! That's when he was oblivious to the fact that there are spreadsheets around and that the horn he was working on answers to the name "tractrix"... the fact that he is a PhD in maths & has 25yrs diy experience helped, I suppose... Cheers! |
Greg, I have the same question as TWL, how do you front load a Lowther? I can figure backloaded horn, but front loaded? Do you have pictures of this beast, a plan or a link? Furthermore, without these schematics or some illustrations, I am curious to figure out how does it cut "mechanically" at 120hz....the subs, everything, you have described is wrecking my brain and now, I am totally obsessed. If you can give me some "fix" I appreciated. Paul |
I tried the Norwegian (the originals, as per Tom) pipes and wasn't thrilled -- with EX-4's. HOWEVER, what is spectacular: front loaded (tactrix horn) PM-4's driven by "good-bandwidth" 300B (i.e. using big Tango OPT) + an open baffle (sub)woof system. The tactrix cuts mechanically @120Hz; the woofs x-over 4th order, passive, preceding woofer amp. And, Tom (Twl) I also experienced PM4's on flat, open baffle with back damping and the same tactrix @ 120Hz. Special construction to support the PM4's. Sound? Oh well... let me not waste server space with superlatives. Unsurprisingly, measured response @ 1 m on axis was +3/-2 db to +19kHz. In room response was ~+/-8db which is outstanding in my book. Now all that's left is money for two PM4's. Better still 4 or 6 to cover mutlichannel needs... I'm rambling -- Mezmo, sorry. |
Yea, I'd love to build a pair of the Voight Pipes myself, and was seriously considering it there for a bit. Tom was kind enough to send me some pointers, I'd picked out the Lowthers I wanted to put in them, and I was on the hairy edge of pulling the trigger. Even had a cabinet-maker friend of mine lined up and we were just trying to figure out what variety of solid hardwood to make'em out of and brainstorming about how to sex them up a bit and turn the basic design into something really special and unique. (Well, actually, he spent most of the time making fun of me for my stereo addiction...). Then reality set in. I too live in a one bedroom appartment, fifth floor walk-up, no less. Moreover, going from Thiels (and equipment to drive the hungry mothers) to horns is no small endevour (especially up and down five flights...). Someday, when I have room for a second system, I'll go the horn route. In the meantime, I suppose I can always impose and listen to someone else's, once they arrive.... As for the friend, his wife is very discerning regarding what finds a home in the living room and what doesn't. When she could not only tolerate but actually liked the Abbeys, there was really no question that they were it. Don't matter how good something might sound, if you can't bring it home, won't do you much good. |
If he was daring, he should have tried to build a set of Voigt Pipes with the Fostex 208 Sigmas. I did this succesfully about 2-3 years ago and still have the cabinets left over. The finish was not "pro" but the sound, the sound for about $400 worth of materials was quite simply staggering. You may ask where did I do the woodwork? Got several large pre cutted plywood boards from Homedepot for about less than $50. Then, at home, I did the bulk of the work. Home= 1 bedroom apartment. It took me about 2 days. I had no previous woodworking experience, but the I had been bitten badly by the DIY bug. So, I did it. Now the Fostex are filling a pair of ZHorn Garudas that I bought from Tom Zuworsky. They sound awesome, especially with my fully battery powered Final Music 5 and 6 preamplifier and amplifiers. The sound is fast, taut, and even without a subwoofer, decently full. To add more PUNCH, I added a powered subwoofer. 10 watts of grainless battery powered glory. No Cairn and Cairn can compete with this. Another interesting set up is what TWL has. Check his system profile. Strange, it makes me drool when I think about it. My dream....to either construct a full, with excellent bass extension horn or get a refurbished Klipsch La Belle/Scala, especially with the AKL or ALK updated crossover and some excellent minimalist wires. That will take me to heaven! PS: I must be somewhere between Earth and Heaven, maybe Purgatory? hehehe |
Well, gentlemen, in case anyone is still paying attention to this one, I thought I might offer a touch of resolution. After much consternation and gnashing of teeth, Jim, the friend of mine that started all this, has commissioned an amp from Mr. Korneff and ordered himself a pair of the Cain & Cain Abbeys. The upstream bits from there are still under debate, but considering the Abbeys are snowed in in Colorado and Jeff's amp magic takes time anyway, there's no rush. Thanks again for the pointers. |
Yes, Marco you can look here for the plans(in metric, and INSIDE DIMENSIONS). http://kosat.consultit.no/~ketil/lowther/voigtpip.html Those are the original Lowther Club of Norway plans, and are the correct ones. Stick with those. The only beneficial mod to make, is to use my "swinging door" mods on the sides of the baffle-board, to extend the width for eliminating baffle-step losses that are common to narrow cabinet designs. Makes the bass much better. They do not ever swing forward of the baffle face, but can be angled backwards to reduce the bass augmentation for certain records. Contact me if you are going to make these. IMO, these with either Fostex or Lowther, on your 300B will have those "twin dishwashers" permanently in the storage room. Here's the rationale. Basically, when you remove the crossover from the speaker system, you are then achieving the same result as "active" speakers. You directly control the driver from the amp, with nothing in between. Big difference. Also, the traditional problems with crossovers and driver overlap are eliminated. Another big difference. Especially since the LaScala crosses over right in the middle of the vocal midrange. Third, you will get just as much top end extension(with Lowthers) and the (40Hz)bass will go lower than your LaScala's. Efficiency is very close, with the Lowthers doing about 100db/watt in the Voigt Pipe cabinets. And, there is a certain technical "synergy" between the SET amp and single driver speaker, that is just unmatchable with any other type of speaker on a SET. They are "made for each other", and you won't ever hear your SET better than on a pair of fullrange single-drivers. This is where the "magic" is. One caveat: Lowthers and other single drivers take a VERY long time to break in. At the start, the bass is poor. They are stiff, and tight tolerances, so you have to start at low volumes, and then increase SPL over the first 30-50 hours. They don't come into their own till after 100-200 hours, and are not fully broken in until after 500 hours. This is very real, and not a "psychological effect". |
Thanks Tom- I've been looking into single-driver solutions to appease my wife while still keeping me happy. She refers to my LaScala's as "the twin dishwashers" and would like nothing better then to see them replaced with something taking up less space and with less of a retro look. In my mind they'd be hard to beat with my 300B SET's but I've heard so many good things about the single-drive solutions that I'd like to investigate further. If they can top a Sonata that is some high praise indeed. Is there anyplace online I can look at plans for the Voight Pipe you built..there seems to be many variations on them? Marco |
Marco, I know a couple of people that have Cain and Cain Abbys and like them. I haven't heard them, but have built some Voigt Pipes with other Fostex drivers.(The Abbys are a Voigt Pipe cabinet). It's hard to beat them for the money, in a single driver speaker. I use Lowther EX3 drivers in the Voigt Pipes now, and I prefer the Lowther, but Lowthers are alot more money than Fostex. And also some people like the sound of the Fostex better. I think it is a worthwhile thing to investigate the Cain and Cain stuff. I built my own cabinets, and got Lowthers in them for the same cost as Abbys with Fostex. Voigt Pipes are an easy build. I know a member who replaced his Silverline Sonata speakers/Electrocompaniet amp, with a pair of DIY Lowther Voigt Pipes and a Wright 2a3 SET amp, and they killed his previous higher power conventional system. He was shocked. I also know of a few other similar stories, including some Lowthers knocking out a pair of Merlin VSM. These are the newer Lowthers with the new improved design. A whole 'nuther smoke. I really think alot of members would be quite surprised to hear what this kind of setup can really do. |
Hey Tom- What do you think of the Cain & Cain (Abbey and Ben) speakers? They utilize a different Fostex driver. They Abbey is $1500 and tbe I-Ben (has tweeter and crossover) $5000. I've been thinking of making the 3-hour trip out to Walla-Walla to take a listen to them. Anyone else have any experience with their speakers? Cain & Cain Marco |
I can't think of many actual horns under $1k. Maybe you might find something vintage for that, but it may not be in perfect condition. Perhaps some older Altecs. You could make some nice Voigt Pipes with Fostex drivers for under $1k. The Hornshoppe and the Z-horns with smaller Fostex are about it, otherwise. Ideally, you'd really want the 8" drivers with higher efficiency for a SET. Regarding the amplifiers, getting a good SET with decent output transformers for under $1k will be a challenge too. Maybe a used FI X 2A3 would be possible. Or a Wright 2A3. The problem is that the really good output transformers can cost over $1k all by themselves. Horn Shoppe and Decware are ok, but the Fostex 103 commonly used in the Hornshoppe "The Horns" are not capable of much volume level. A 4" driver can only do so much. Out of the Decware stuff, probably the Jack Elliano designed DRD amps would be my choice. Jack is a good designer. |
Much appreciated, all. Clueless, a hot tip -- but, no, I wasnÂt fast enough. Recognizing (I think) that it's unlikely to hit the magic combo right out of the gate, he's currently thinking about relatively budget gear with some DIY thrown in just to get things going in the right direction. This is all new to me, but the great bit is I get to play along, too. First things he mentioned, by way of example, were the Horne Shoppe and Decware -- and I'm guessing budget is under $1k for each of speakers and amp (and from there, ideas unsettled. I did try to drag him to Avantguard, but thatÂs definitely not the direction things are headed). My role in this, at this point, is the trigger guy ("do it, do it, do it -- pull the trigger") and have even offered to loan an extra preamp or two and a CD player to the cause if it makes the initial leap any easier. Trick is, over the course of the past year and a half, I'm sure that he's read just about everything there is to read on the subject at least once and is now paralyzed by too much information and no way to make any of it concrete by actually listening to any of the stuff. Knowledge is power, sure, but in the days of the internet driven info-glut it's often just befuddling. (Who was it that defined the information age as an explosion in the amount of information it is safe to ignore?) IÂm just trying to come up with ways to break the stalemate... P.S. When I told him that I was a junkie around these parts and playing along and all that, he warned me to "watch out for those guys" (from one prone to morbid, serial addiction to another). I, of course, let him know that I was "one of those guys" and that he was the one in trouble. |
I also like the Jeff Korneff amps. You might consider Jack Elliano's Ultrapath preamp too. That is getting a bit of attention lately. For the speakers, the DIY route is very popular with the triode/horn crowd. For real front-loaded horns, try the Oris 150, kit or built. It uses a powered subwoofer under 150Hz, but can use low power SET above 150Hz. If you like a back-loaded horn, then the Hedlund Horns are a nice project, or you can get them already built by Hornet Audio. Not real cheap, but nice. Another nice back horn is the Lammhorn 1.8(not a kit). For the cheapest, but still very good sounding single driver Voigt Pipe setup, try the Cain and Cain Abby's or even making your own with Lowther or Fostex drivers. Easy woodworking, no crossover to build, and very nice sound when done right. You might be able to keep the whole package of source, preamp, amp, and speakers and cables under $5k, if you are a good shopper and do some DIY. And this would yield very excellent sound too. |
I can contribute a recent experience that might help...I don't know really, but I think it is interesting: If you check out my "Virtual System" you'll see I use a system similar to what your friend is contemplating. I love the sound it produces, and yes, it is unusual, distinctive, eclectic if you will. I've been through quite a few different tube amps to find out that this is probably my favorite overall type of system. I'm going to limit my comments to those more easily understood by a layperson (which is what I'd consider myself anyway), mostly cause my technical vocabulary in this hobby is limited. I do know what I like when I hear it though. So here goes: Last night I brought home my beloved Quicksilver MiniMites that power my work system. I had a bit of a SNAFU covered on another recent thread and needed to bring them home for a complex surgical extraction (see the thread). Once the operation was complete I thought, why not plug in these amps in place of my 300B SET's in my home system (also much beloved) and give that combination a try. I had some idea's of what I thought the results would be given the variables: 300B SET mono amps putting out 8 watts per side vs KT88 Push/Pull amps putting out 35 watts per side. I loved both amps in their respective systems, but had never tried moving them. In my home system I'd be putting the push-pull MM's with my 104db efficient LaScala's (horn based). I am very used to the sound of the SET's at home on that system...when I plugged in the MM's and fired up some Gillian Welch the sound was, now I'm being very critical here as I'm definitely spoiled by SET there, rather brash and 'vulgur' for the lack of a better word. It sounded like amplified music. The soundstage was narrowed, the warm glow I so love with the SET amps was gone replaced by a punchy and crystalline detail at the center which seemed to grow more and more vague as the stage went out to it's rather limited width. Gone too was the holographic feeling of the SET. Bass was there like the SET could never duplicate, and was a bit too much for my tastes. The bass also lacked some definition. Drums did not sound like drums, they sounded like amplified drums. I left the system on overnight and listened again in the morning....not much better. I packed up the MM's and hooked the SET's back up. Fired up the same disk. It's like being at a warm fire...all of a sudden you are listening to the real thing. The instruments have a shape and a 'glow' somehow to them. There is a naturalness to the music. With the MM and the LaScala's I was reminded of many detractor's comments about horn speakers sounding more like someone shouting at you (yet if you read on you will see they do not have that effect at all with other horns). SET seems to me to color the music, but in a way that is oh so attractive and engaging to me.....in warm hues of oranges, yellows and reds that draw you in and envelope you. One thing I've also come to love about this sound is that its effect is NOT lost when you leave the sweet spot. Walking around all parts of the house the warmth and 'presence' of the sound is still there. Soundstage and holography of course are gone, but the glow is still a very present and pleasing element. So here is what is confusing to me about all of this. I bring back the MM's to where they came from in my studio sytem, which is slightly less efficient horns from the same 'family' (Klipsch Heresys - 94db), and that combination is utterly magical and engaging. The soundstage is huge, the sound is musical and toe-tap factor way up there. Holography is present. It is not the same warm 'glow' from the SET at home, but then again, it is far away from the very brash sounds the MM's made when they were installed in that system at home. So what gives?! The only explanation that I can offer is simply one of synergy. Different pre-amps, sources cables and rooms are working against the MM's in the home system. It would be interesting to bring my SET amps to work as I'd like to see what that sounded like. I have moved my two pre-amps back and forth and it makes a profound difference in the sound of the systems. Each is much 'happier' with the pre-amp I've chosen for it. Anyway, I'm really happy with both systems, but I can tell you for sure that my experience of SET is one that is entirely distinctive of any other form of amplification I have heard. It does lack a full range, though the SET amps I have are pretty strong in bass and quite enough for my tastes. But if you are used to and like the SS low range punch you will be likely disappointed with SET lack of that quality. SET is all about a liquid midrange, holography and this kind of nebulous glowing warmth. It does sound colored to my ears, but you can color me happy! I am certain that it is not necessarily a sound that everyone would like, so your friend is right to seek out a good example he can listen to. Unfortunately I am on the other coast and it's been over ten years since I lived in NYC (my home town), so I don't know the high-end shops and their wares anymore. You can send him to a real extreme and have him visit Avante Garde's showroom, though those are not really single-source horns. He may be able to find some resources on the Single Driver Website under the links there. Hope that can be of some help. Marco |
I'm not from the NYC area but reply to Dave from this thread. If you can make the Oct 14 event with Alan Wright that would be a bonus in my book. Have to act really fast! If you are too late still email him. He is involved in lots of activities in the NYC area and is always willing to answer Q's online. Friendly type. http://www.audioasylum.com/forums/tubediy/messages/38603.html Here is a picture of Dave's system: http://www.arduman.com/aa/Sayfalar/slagle/slagle.htm He will certainly get you in touch with low power HE speaker types in the NYC area. A nice chance to meet and talk to experts in your neck of the woods. If you are into homebrew try Welborne and diyhifi kits. After listening to the latter I've just orderd the former just for fun. Need to have a budget to get very specific about recomendations. I remain, |
This should keep him occupied for the next year or so: http://www.audioasylum.com/forums/HUG/bbs.html http://www.audioasylum.com/audio/tubes/bbs.html http://www.audioasylum.com/forums/tubediy/bbs.html http://www.audioasylum.com/forums/tubediy/bbs.html http://www.audioasylum.com/forums/bottlehead/bbs.html http://www.audioasylum.com/forums/welborne/bbs.html http://melhuish.org/audio/ |
