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I haven't experimented with Lowthers in OBs but I might add a few ideas that those who are may try.The PM6a driver may be the most appropriate for OB loading since it has the smallest magnet and thus probably a bit lower efficiency/less top-heavy sound. The larger-magnet drivers are really intended for horn loading. Sometimes cheaper is better!
The JE Labs OB design uses a bit of floor bounce to fill in the lower midrange/upper bass, which might be very welcome with this sort of driver.
Since Lowthers are a bit at risk of being top-heavy (thin) in an OB design, I'd try upping the Zout of the tube amplifier by using 16 ohm taps on the 8 ohm driver. This might help fill out the lower midrange. I've long thought it would be fun to try true-pentode or true-tetrode output stages, ie current amplifiers, with Lowthers in OB. What is the sound of one 6550 clapping?
Due to their design the Lowther drivers are particularly excursion-constrained which is normally not so much of a problem with back horn loading. However, in an OB installation they are really flapping around uselessly in the bass region. I would at least experiment with simple line-level highpass filtering, at the very least a 6db slope (one capacitor) filter at 100hz or so.
I've heard the 3rd Rethms before and was impressed with the mids and highs. However excellent they were they could not overcome the lack of bass.Good to see that Jacob (very much an enthusiast and actually answers questions) recognized that the Dx55 is a midrange driver and added bass drivers to the 3rds. This is not a novel approach as Horning speakers incorporate bass drivers too. And the Horning speaker I heard has very interesting dynamics in the midrange unlike most <92db speakers. The Lowther seems to resolve the range between 150 to 1000Hz better than most low efficency drivers.
I've a pair of the DX55 it has the magic. I'm trying to front load (perhaps a short throw waveguide?) it somehow without wrecking the top end.
Paul,I am one who has been there and still is in the midst of trying to find MY way of getting the best/widest potential from the better, and unfortunately, often more expensive full/wide range drivers out there. I have found that I prefer the "you are there. they are here" Live sound of Lowthers to all of my other drivers. Yes, Warts and all. Here re my strong suggestions from experience. There aint NO such thing as a full range Lowher in any cabinet type and size that will fit in my auio room. Caviot, They don't come close to doing full range or even satisfying bass, but the better Lowthers offer wonderfull high frequencies in my opinion an depend on keeping their upper range potential in tact o deliver the spooky coherant magic that they are known for and capable of.
I am an absolute firm believer (from many many many trials) that you gotta forget about fitering Lowthers or curtailing them with xovers if you want the magic that hey are capable of.
I've got front, back horns and ass reflex cabinets here. All can sound nice to varying degrees with Lowthers' as well as many of my other wide range drivers. I have no place left to store a Baltic Birch cbinet. Fiberglass and plastic or the 150 HZ front horns.
Who knew hat all I ever needed to begin (may turn out to be the end game) to realize the best (by far) that certain Lowthers' have to offer were two (one per side) 35" wide by 30" high 3/4" ply or MDF attached to sloping 90 degree wings/stands 5" at the tops to 12"'s at the floor to realize the best sound that I have ever had in my home. And I have been doing this or a long time. Oh, by the way, these wonderous slabs of wood that have completely changed my speaker paradigm are JE LABS design. Do yourself a great big favor and go to their web site where they supply illustations on how to build these Open Baffles that a 5 year old could accomplish.
So what is the catch or catches? Your gonna love how simple this/these really are. First, FORGET ABOUT THIS BEING FULL RANGE IN THE BOTTOM END PERIOD!!! Ok, now here's the good news part. If you use some DX4's or PM2MKII's (More on regular PM2a's and PM6a's to come. ), then I have absolutely NO need or desire for ditional tweets. I have tried some of Fostex's best and just did not feel their need.
Now for the bass stuff. The eight inch Lowthers have been measured to be strong (it may have measured strong to 85 HZ but did'nt sound strong to me) to aound 85 HZ in these JE LABS OB's. The cool thing here is that ,at least for me, any bass below 100 HZ is non-directional to me. So, I have my OB's pulled six feet out from the front wall and my dual sub woofers placed in the corners six feet or so behind them (really only need the one woofer though). The Lowthers run full range and the plate amp crossovers, run directly off of the Yamamoto's main speaker terminals operate at 85 hz and below. My simple subs gel seamlessly with he Lowther stuffed OB's.
Like $100 in wood, my son built them, and this setup wipes out any other cabinet type that I have stuffed these drivers in.Here is the other and perhaps the most confusing or confounding finding during my OB enlightenment.
I have/had been happiest with my current edition Lowther DX-4's in my favorite Medallion III back horns and 150HZ tractrix front horns augmented by my previously mentioned corner transmission line subwoofers. I had recently recieved a pair of Lowther PM2MKII Alnicodrivers to try out. These drivers have the same magnetic flux density (2.2) as my Lowther DX-4's. They actually use the same magnt rin used by the PM4 but the PM2MKII's are fitted with a softer and magnetically weaker pole and top plate. Hence the 2.2 Vs. 2.4 flux desity of the PM4's.
So, why the hell bore you with info bout a Lowther driver that is no loger on their list of current items (they can and will make them at your request)? Because, In these simple OB's, for what ever reason, these big magneted son's of bitches are (by a wide margin) most spooky real sounding speakers that I have ever heard. Funny thing is that I prefered my DX-4's to the PM2MKII's in my back and front horns. As a matter of fact, the OB's had just been completed (no paint or nothin) at the same time that I was packing the PM2MKII's up for return from wence they came. I figured that they were e only drivers not either currently bosed up or screwed into cabinets so why not see how these OB's sounded. I had low expectations for both the drivers nd he OB's. You already know the results, STUNNED! is an understatement. I put two and two together and assummed that the DX-4's and even my new Fostex FE206ES-R's would sounnd even better. I cuold not have been more wrong! All of my other full rangers sound quite nice in he OB's and in my opinion preferable to my other cabinet combinations, but not even in the same ball park as the real live music comming from the PM2MKII OB combination.Lowther UK claims (I contacted them immediately to see if they had added fairy dust ot something to PM2MKII's) that it surely has to due ith the gret amoun of air in the gap of such a large magnet.
How to get to the bottom of this? Well, I have the DX-4's and PM2MKII alnicos. I now have a run in (Iran um in for weeks) PM2a' and PM6a's to test. I informed Jon Ver Halen, one of two US Lowther distributersof Lowther drivers of my findings. He immediately replaced his DX-4's with a pair of PM6a's in his current Open Baffles nd was stunned as well. Maybe he will add his own two cents about his pleaent surprise. I wlll soon find out for myself if the less expensive PM2a's and PM6a's also derive similar "MAGIC" in these simple and inexpensive open baffles. I wll post my fidings if this post generates enough interest. I sincerely hope that the other two large air gapped alnico Lowther magneted drivers offer the same or very close to the same stunning sound in these OB's as the PM2MKII's do. Either way I would forget about other expenive and exotic cabinets and gt a pair of Lowther PM2MKII's or hopefully regular PM2a or PM6a's. Add a subwoofer+Plate amp nd lw powered set amp todrive the fat magneted Lowthers and just forget about the peaker race.
One more thing, I have just had constructed (from Balic Birch) a pair of OB's that are contucted like the JE Labs accept one pair mesures 21" wide by 48" tall, and the other pair is 30" ide by 48" tall. Both pairs slant back at a bit lesser anle than do the JE Labs because the main divers are mounted at 29" instead of 13" cntered off the floor as with the JE Labs OB's.
The new baffles are also fittd wih 15" bass drivers with a QTS of .58 and wil be driven and crossed over (probably around 150 HZ) using two Bash plate amps. The bass divers are centered at ten inches off the floor. Also, the Lowthers nd all full rane drivers tested will run wide open, with NO filtering. See ya.
Lowthers in back horns CAN deliver fairly deep bass, but you need the right style cabinet. The Big Fun horn and Miroslov's Veliki are examples of back horn speakers which can achieve flat bass down to 35 hz or so, which is pretty deep.That is interesting about your findings that the PM2MKII drivers sound better than the DX4s on open baffles. Do you use a crossover with the PM2MKII drivers (if not, how do you avoid the rising frequency response)? It could be that the PM2s sound better solely because of the resulting frequency response. Perhaps if the DX4s had the same frequency response they would sound similar??? I use a single air core inductor in series with my Lowther drivers (minimal impact on sound quality).
Lowthers are better if high passed as it protects the sound quality of the midrange (and the integrity of the driver itself, unless if you play it at very low levels), and I agree that open baffle designs are more transparent than boxed speakers. Even with open baffles, high passing the Lowthers provides an improvement. I do this by using smaller coupling capacitors in my SE amps, which are there anyways so I am not adding any additional components to the audio chain that weren't there to begin with.
There is a lot of tweaking that can be done to OB cabinets. I would NOT use wings at 90 degrees (although that is how my design is now), but at some more open angle as it will reduce resonances. Also, the back of the baffle is helped by some sound absorption material.
I also would not use parallel sides as it increases resonances at specific frequencies due to edge defraction. Also, the edges should be of a large radius to limit edge defraction.
I think that 3/4 inch plywood is too thin for OB speakers. Because the speaker does not benefit from the sturdyness of a box, a thicker baffle is in order; especially since you are adding a bass driver to the same baffle. In my setup, I also have 15 inch drivers on the same baffle as the Lowthers and even with a second set of 18 inch drivers in a second dipole setup, the 15 inch drivers shake the 3/4 inch baffles too much.
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Ultra-consumers: Spending money they do not have to buy things they do not need to impress people they do not like.
I had Lowther DX3 on open bafle for about 2 years, I used ALtec 416 for bass. After some time I noticed that even with focus on the center Open Bafles do terrible imaging, things would move from one place to another and nothing was clearly coming from one direction.
The tone was excellent though and the lowthers would go down nicely to about 100hz.
I also found its a bad idea to rest the OB on top of the bass cabinet, midrange would suffer. I mechanically decoupled both with great results. Try writting a letter in a moving car...try using your nice handwriting now....
One of my friends has independently reached exactly the same conclusions, Lance. He comes to Japan every once in a while and is extremely interested in the Feastrex/Exact type of fullranges, and it is conceivable that he might pick up a pair for himself after his next visit (whenever that is), but for now at least his setup is almost exactly like the one you described. His way of arriving there even sounds somewhat similar, although I don't think he was ever into rear loading. Other than that, your stories are almost identical in the major points.
Hm, what would make theem different from any other so-called full-range drivers crap?
Hey Romy, some day you're going to die, your stereo will get parted out, and what people will remember most is how much of an arrogant ass you were.
Romy, that was just a bit of ribbing. I put some stock in your opinions too (having read some in the archives) but you're certainly extreme in your positions and language. Certainly even you must admit that *some* single-driver speakers systems sound at least *Ok*?
"An open baffle built around 1939 Tekefunken’s 8” field-coil, combined with EV T35 tweeter, driven at 45V by Fluke 407D power supply with a supplementary sealed LF line-array."
Romy may pass away and his system may get parted out but it will still be better than struggling with Lowthers for years on end.
I owned PM6a's for almost a decade and tried virtually everything to get them to sound the way I was told they should be and they're still a mid range driver. If you think otherwise that's OK but I'm happier with Altecs and just listening to music instead of agonising over the back horn or placement etc. I'd probably put a bid in on Romy's "parted out" system if you're going to off him.
Anyone who googles Feastrex has probably seen Roman Bessnow's exceedingly unflattering remarks about their products, based on a very brief listen at CES 2006.My feeling is that in general, much of what Roman says is spot on the money and thus valuable. The remainder should simply be filtered out by the reader.
For some people -- such as manufacturers -- negative criticism can be exceedingly valuable. The people at Feastrex are happy whenever anyone provides some advice or a hint (either direct or indirect) on how they can improve their speakers, and I expect that most manufacturers feel the same way. (If they don't feel that way, they sure can't expect to see much improvement in the future.) Thus the folks at Feastrex felt genuinely grateful for Roman's criticisms, because there were some valuable insights among them. The products are better today as a result. If I was a manufacturer I would definitely be happy for his opinions. Praise may feel good but it is not going to help you discover your weaknesses.
> > > My feeling is that in general, much of what Roman says is spot on the money and thus valuable. The remainder should simply be filtered out by the reader. < < <Perhaps if Roman communicated in a less inflammatory, 'definitive', arrogant / aggressive manner, others would be more open to his 'suggestions'. The antagonising crusader persona wears thin if over-used.
As you say, criticism - or more appropriately, feedback - can be helpful.
Kind regards
Raymond
Ultra-consumers: Spending money they do not have to buy things they do not need to impress people they do not like.
"Perhaps if Roman communicated in a less inflammatory, 'definitive', arrogant / aggressive manner, others would be more open to his 'suggestions'."Then he'd be just another know-it-all audio bore. We have more than enough of those.
Curious you find that "less inflammatory, 'definitive', arrogant / aggressive manner," equates to "just another know-it-all audio bore". I understand how someone could make this unqualified association, but Ivan, that just ain't necessarily so. There are other forms of titillation than inflammatory remarks, aggression, insults, and inflicting pain on others, etc. As for subjective definitives (oxymoron intended)...Why you associate some mutual respect with "know-it-all" types I am not quite sure; perhaps you are luring a response from a boring know-it-all to support your argument. Problem is, I know f@%k all and am not always boring (I hope!).
Regards
Raymond
Ultra-consumers: Spending money they do not have to buy things they do not need to impress people they do not like.
I'm excited about them. I vividly remember my first time to hear the Third Rethms some years ago. I loved their sound. But I could not accept the thinness. With the new generation they should be fuller sounding and I'm very curious to hear them.
I couldn't accept their "weirdness" but I'm past that now. I had a serious single-driver bias to overcome, I think...
Certainly a nice review. My heart goes out to all that battle the Lowther implementation issues. It is a tough moment when one realizes that Lowther's are basically mid range drivers with issues that require
the moving of mountains to correct.
Hopefully this new design will propel Rethm into the spotlight as a desirable and sought after solution for the creation of an enthralling listening experience for the audiophile.
Regards,
Lew
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