Ohm Walsh Micro Talls: who's actually heard 'em?
How do you make five hours fly by fast..... Man I love fiddling with stereo equipment. The smell of hot tubes, transistors and power supplies brings back memories from the mid seventies when I was a spry teenager. I walk by the stereo shop on the way to school everyday and finally I decided to enter the inner sanctum of my dreams.....Ahhh that smell from the tubes, transistors and power supplies were intoxicating and with that the beginning of a lifelong quest for better sound. When I started to take apart 4/5k's it really wasn't because I didn't love the way they sound, but because I took apart the Micros. The shock seeing the mess of a badly built speaker with parts so cheap rattled me, so my curiosity was peeked and the 4/5k project took a on a life of its own. Today was an eye opener again, but in my infinite wisdom I decided to use a different software to measure the frequency response. The software is great, but transfer the graphs in to a file that a human can see was another matter. So I am going to have to take pictures of the screen and then post them as soon as possible. What new things did I learn today? How about the speaker measures better with more dampening in the cabinet. A little bit of EQ will go a long way for perfection. No output beyond 2.5k on the Walsh driver. A non resonant cabinet sounds better. And much more. I manage to massage out a perfectly (or close to it) frequency response. The ribbon tweeter sounds and measures great even when I'm over 20 degree of to the side but not as great vertically. I also believe an electronic X-over is a must for this design if you want to squeeze out maximum performance. So that's how I manage to spend five hours nerding out on drivers, EQ's and acoustic sound dampening.......🇸🇪 |
Here I am with some more info to add to our arsenal of knowledge and understanding about our beloved Ohm speakers. It took some extra time to pull together additional charts to show what really is happening through the frequency sweep. I always suspected the Walsh driver to be great but not fantastic in the upper frequency region. After looking closely at the Walsh driver the conclusion must be that the application is brilliant, but not the latest in resolution or frequency extension. The Walsh driver works like an “F” driver but nowhere near it’s extension in the treble region, and if you are really honest at all, there’s very little difference between a front firing woofer/midrange driver and the Walsh driver. The difference is a removed dust cap and some tacky glue on the lower (bass) part (for damping I suspect). The 360 degrees off radiating sound is certainly one of the appealing reason for getting the Ohm’s. Let’s take a look at the different readouts. The first will be a 3D plot that shows both time and frequency in a dimensional way. The brighter the sweep is the more energy is emanating from the driver, you can also see valleys which are low energy areas. These measurements were taken at approx 15 inches from the drivers so I don’t think the room boundaries made any difference at all. The driver was the original soft dome tweeter, no extra EQ the only difference would be that it’s not confined behind foam, paint, perforated steel and speaker cloth I.E. no CAN. (4 layers) Image one: The Walsh driver no tweeter. Volume would be at about mid 80db, loud but not overly so. The bass frequency is a seams a bit on the plump side and then a suddenly a drop in energy way earlier then expected. (wideband Pink Noise). https://www.flickr.com/photos/147883144@N08/shares/D26z27
Image two: Here you have a full frequency sweep allowing you to really see what’s going on, and suddenly it drops of the cliff at 16k. (wideband Pink Noise). https://www.flickr.com/photos/147883144@N08/shares/b1976f
Image three: Walsh with stock tweeter, no EQ, padded cabinet but no OE padding which would consist of a 3 inch layer of re-constituted (shredded and glued together) denim, fluffy Dacron and an upper layer of netting separating the fluffy stuff from the Walsh driver. The graph confirms the 3D plot, very bass heavy and then it falls of pretty fast. These measurements were taken approx 1meter from both drivers. Frequency sweep 20-20khz https://www.flickr.com/photos/147883144@N08/shares/WrD31L
Image four: Walsh driver, stock tweeter, EQ and complete stuffing. 20-20khz Wow look at that curve, so much better…Way better and more midrange/treble energy. And the bass is under control. Very little smoothing as I really like to see all the ripples warts and all. The EQ was used with a tender touch nothing heavy handed. https://www.flickr.com/photos/147883144@N08/shares/8Y1zqV
Image five: (white trace) Walsh driver stock tweeter, no EQ, light stuffing 20-200hz https://www.flickr.com/photos/147883144@N08/shares/7fGU4j
Image six: (yellow trace) Walsh driver, stock tweeter, no EQ, complete stuffing 20-200hz A small but clear difference if you look closely, a slightly flatter curve, but remember this is a very small slice of the whole frequency curve. https://www.flickr.com/photos/147883144@N08/shares/5ffK60
Image seven: Walsh driver, ribbon tweeter, EQ and complete stuffing 20-20khz As mentioned earlier the impedance value is 5 ohm’s on this tweeter, so that will certainly add to some compatibility issues. But looking at the curve it’s pretty darn good and I think with some additional tweaking I could have done more. Below you’ll find an additional image of the same setup but 20 degrees off axis. https://www.flickr.com/photos/147883144@N08/shares/k4b4M0 https://www.flickr.com/photos/147883144@N08/shares/b5016x |
Hi Mapman.... I used multiple software versions to see if there's some issues but nothing is changing, if anything it's showing about the same readout from test to test. Go back in my posts and I have mentioned the 2.5k drop off many times and there's nothing beyond that number. Nothing wrong with the speakers, as a matter of fact I mentioned how much I love them, but I'm the fiddling man and with that most everything get upgraded. There was nothing wrong at all, both measures the same (what's the chance both are screwed up). I do think people expect more then the Walsh driver can deliver. I just deleted those pesky (lol) switches very interesting and man does he use cheap wire in the switching network....🇸🇪 |
Here you go, the original measurement of the Walsh driver... http://s1248.photobucket.com/user/peterhorvath6233/media/image_zpsomfobhuk.jpeg.html?sort=4&o=8 |
" I was sure that a 1/3-octave frequency sweep would reveal an aberrant frequency response" That doesn't sound like someone who does a lot of testing! A 1/3 octave resolution is as corse as my software allows to go and I would never use that for serious testing. It's kind of using 10000 iso for portrait photography or gravel instead of sand for a foundation not to smart. Look at the readout, it gives you a feeling for whats going on but thats it. This readout was me watching TV, not testing. http://s1248.photobucket.com/user/peterhorvath6233/media/image_zpstgppmvnp.png.html?o=0 |
Mapman being a fanboy is one thing, but questioning and seeing plenty of frequency charts from 2 different software packages and still think that some thing is wrong (two separate drivers looking identical) is a little silly. I have been in the audio industry for years although I'm retired at this point gives me some background to say what you see is correct. Never said I had to make large corrections but the Walsh driver does what it does and not one bit more.... |
Thank you t8kc.... everything I have done it has been on the up and up as I really don't have a dog in the fight. (just a bit) this is suppose to be for fun not a Paine in the rear end.... I started to deconstruct the spaghetti switch box, and finally removed the switcher late this afternoon. And I will replace all the nasty cheap stuff with copper or silver (all of them) and I'll replace them with WyreWorlds new OFC copper as I do care? I have capabilities of measuring FFT and laser interferometry if necessary. The top plate is now floating on top of the cabinet held down with wing nuts. The plan is to make a constrained layer part with aluminum, silicon sheets and Finnply, this should be a exciting next few weeks. I might even construct a 10 inch F clone from some very cool materials as I was privy to at my last job in material sciences... 1/3 octave is like driving a Beetle, my preference would be a Porsche Gt 3 RS that allows much much higher resolution...🇸🇪 PS. The McClaren 650 S is even better, lighter and cool as..s#*_! |
Finally some action on the thread...lol I think the big surprises for everyone is the Walsh driver falling of so early. The opportunity for me to take a closer look at each driver is pretty much exclusive in the whole scheme of things IE no one else has done it as far as I have seen around the net. The extension of the tweeter is weird, looks like a filter blocking the signal. I am ordering up a new cable for my signal generator to see if that's an issue. I did take the switch circuit out yesterday and I'm going back to work on it momentarily. Im sure cleaning up the wiring mess and removing the switches will greatly improve imaging and dynamic response. One odd thing is that the signal is inverted right at the signal input so I will test that out.... Till then.......🇸🇪 |
Soooooo..... The thought I had was, what would happen if I bypass the Ohm X-over and insert my own that I built for another project. The X-over is a simple 8 ohm (wrong impedance) cheap parts that I used for testing and voila' my friends!! It worked like a charm, not perfect as It need to be a 4 ohm impedance unit, but never the less it works. I'm surprised every day and It's a blast, can't wait to continue with some more testing. More to come soon my friends....🇸🇪 |
So it's Saturday and I'm suppose to do some pre tax work for the CPA but I'll do that later...hehehe After holding of on digging in to the crossover board, I finally said "to hell with caution" and removed the the whole board...barabing It is amazing how complicated and convoluted the whole design is. The switching network can not do anything positive for the audio signal. No oxygen free copper as far as the eye can see and plenty of HMG.......Hot melt glue lol So all that is going bye bye, a new design for the tweeter modules with micro adjustability for time alignment and the Rear tweeter will have a volume control. The top plate where the Walsh driver is attached will be made from a sandwich of aluminum, and rubber and I'm decoupling the plate from the cabinet as much as possible. So........that's it for now.........🇸🇪 |
Good morning my friend... Its always fun to meet new forum member in the flesh. Tate was kind enough to bring his 2/2000 and at a precursory listen I was pleasantly surprised. Tate left the speakers for me to do some deep deep testing and some measurements when I get a chance so we'll find out how they measure in a few days...... The Ambien is asking me to lay down the iPad before I say something I'll regret in the morning...🇸🇪 |
Hey Tate..... Its almost 1:30 and I'm up, I played around just for fun with the 2/2000's and the first reaction was holy shit these are very hard to drive.....As I have a numerical volume control and I went waaaaaaaaay further then any speaker I own for the same volume level. The other thing is the way JS told you to aim the speakers is wrong, way wrong. Just this little of moving the speaker about makes for a much better experience. They also like to be back from the back wall 6' worked great. So I think you need a minimum of 500 ponys to get them to sing properly. I also lifted them up on some books to see if the base was better.....yes And I think you get better midrange energy emenating closer to ear height. I will try to get some measurements tomorrow, but I have to see my metal guy for some laser cut parts asap... Its coming together nicely.........🇸🇪 |
Evening gents or ladies.... Finally got home from the metal shop and made some changes to the 2/2000. Found them to heavy in the bass as they were sitting about an inch or so from the carpet...yikes. Found some footers lifting them up another 3/4" and put them on my concrete platforms. Much better and there's still some midrange suckout that bothers both Tate and my self. The marking for direction was off big time, so I rotated the Speaker so the tweeter was aimed at the seating position. Wow better intelligibility, soundstaging and overall more fun. I think the speaker would sound way better crossed over at 80hz and have the subs pick up the heavy work. As they are they suck HP like mofo's almost in Apogee territory...lol I attached an image of the velocity stack now I just need to make it flush with the bottom of the speaker. I also came up with some F1 tech I want to add (I'll show it when speaker is done). I also have a very cool way to de-couple the tweeter module from the main body of the speaker......🇸🇪 https://www.flickr.com/photos/147883144@N08/32258881340/in/dateposted-public/ |
After hours of listening to the 2/2000 I figured something was wrong with the bass and I needed to investigate further. The first thing was a monstrous air leak at the Left speaker mounting plate. This was fixed with a simple liberal helping of high viscous super glue..... At this point I would have thought the problem would have been fixed, so I ran frequency sweep and found a weird hump at the lower frequencies on the Right speaker.....what the heck could it be? Fast forward to this afternoon and after some inspection I found that the bass port tube had dislodged it self. Good and bad I guess, but I did get a chance to look at the innards of a 2/2000.....hehehe 5/8" particle board on the sides and bottom panel. As for bracing it had 2 fir braces that looked more as holders for the stuffing then bracing. Two third of the bottom cavity was devoid of anything. If Tate wants me to fix the tube I'll be happy too. So back to the 4/5000... I decided to remove the bottom panel take out everything and start over. first I need to dampen the wall of the cabinet in a proper way, I will most likely use 1/4" aluminum, noise dampening sheeting and wool stuffening. Bracing will be either Some mdf/ aluminum mix or carbon fiber profiles available to me. I figured I have so much time invested why not do it right.....yeehaw 🇸🇪 |
It's funny that you gave some technical help as I was sitting and looking for ceramic ball bearings for part of my build (thank you McMaster). I also have looked in to this paper epoxy countertop material that's incredibly dense and easy to machine with carbide tipped tools. I am also planing on doing a little YouTube video series on the build up, should be fun. Im hoping to get started tomorrow with some video clips talking about some of my ideas and what I'm expecting from the build up. Then in to the shop cutting the bottom panel out remove all the poor bracing from Ohm and plan on something new but looking like something you would find in a 800 series B&W. I might make a false wall on the outside panel. Fill it with dry sand to dampen vibrations. The top mounting plate will be a sandwich of 3/16" steel and two sheets of 1/8" aluminum dampened with proper butyl rubber sheeting and glue. And to add extra stability to the whole part I'm adding 1/8" thick water jetted carbon plate. If I had some more cash I would laser cut 1/2" plates to add even more stability..... 💯 Hope you guys are excited to see what can be done to make this speaker amazing...🇸🇪 |
Hi enginedr1960... (And it looks like the tread is getting some action). The idea is to keep the cabinets dimension on the outside the same, but the inside will be remotely nothing like Mr. Walsh had originally designed. So basically what I'm making is a box in a box. Between the two walls there will be butyl rubber and sand. Due to the the way I'm stiffening the cabinet walls I will have to compartamentalize the sand pockets but I might drill holes between the layers. It'll be bitchin I promise. Any down side to all this? Yes the speaker will be way heavier, but hey that's OK with me. Next project this morning is Tate's 2/2000 I'll take pictures and post them later.... As one of my favorite YouTube personalities say when signing of... Keep your d.... in the vice ;) 🇸🇪 |
So after an afternoon of working on the 2/2000's I found a few reasons to cheer. I took em apart as one of the paper tubes were loose which set up some strange frequency issues/ chuffing which sucks. After looking at the sparse wadding, loose paper roll and a cabinet ringing from no sound deadening, I asked Tate if it was OK if I could do some changes, he declined but I felt that he had loaned me the speakers so I did some anyway......Sorry bud lol So I installed the velocity stacks, sound deadening/ polyfill, caulked the air leaks. I realized that there was a switch on the x-over played around with it for a while and......Voila' I also rotated the "Can" so the tweeter was pointing towards the listening position. So why isn't Ohm doing this to the speakers is beyond me, now it's sounding fantastic with great imaging proper midrange and overall a great speaker. Dont give up, anything is possible if you try hard enough......🇸🇪 |
With those kind of answers for issues, you do have to question who is running the shop on a day to day basis. Much can an should be done when you charge $1200 for an upgrade. I would include a new bass port tube, Polly fill and maybe some cabinet braces to glue in. And how about the switchable x-over that no one has mentioned once ?? Just a thought, time to go to bed gents....🇸🇪 |
Hey.... Did you look inside the cabinet? As far as I know (but Tate can tell you) he got all the parts from Ohm with the markings for direction of tweeter etc. what I did is totally different, and if it would be my own speakers I would have gone further. But again the speakers are on loan from Mr. Tate :) I did play some very dynamic music running my subs and my wife absolutely loved and it was disco loud and still pleasant... As far as for the Walsh driver read my previous take on them and looking at these I'm spot on. Nothing beats a drum....🇸🇪 |
Accurus thank you for calling a spade a spade... After seeing a lot of cracked open cans, I do agree on the sentiment that if let's say Paradigm or pSB would have such sub par build quality they would be out of business or at least laughed out of the sandbox. As someone with manufacturing background I look at the Ohm's and see a diamond in the rough. But currently they look stuck in 1978 a good year for me, but time marches on for everything including speakers. Toiletpaper rolls should be banned from speakers....🇸🇪 |
I'm up early as I'm itching to demolish the inside of my 4/5000, buuuuuuut I have to see my Dr. for a torn shoulder ( something ) this morning that I got when I was rear ended a few months back. If they really wanted to figure out a way to rotate the basket (can) without having to make all sorts of new holes it would be so very easy...... Make a main ring that's bolted to the speakerbox, have multiple threaded holes in a lets say 30 degree arc either way. The speaker will fit inside the ring grove.....rotate bolt down. You can have these rings cast so the cost would be minimal in the whole scheme of things thread the holes as needed and powder-coat/paint to match driver or chrome as a beauty ring.........Your welcome. There are no problems only solutions.....🇸🇪 |
Exactly what they did for me, the only difference was the model of speaker. still nowhere close to being OK, lots of cutting corners for a $5000 speaker. I still enjoyed them for quite a long time and looking forward to re-building them to a new level of performance... unfortunatly I just got the news an hour ago that my dad isn't doing very well, so I have to fly out to Sweden on Tuesday and I might stay there for a few weeks depending on the situation. |
Thank you Frazuer1... Trip got delayed a few days as I forgot that my Swedish passport was only good for five years. On Tuesday morning I will know if I can get a temporary passport in a few days. Had the pleasure seeing Tate again, I have done some substantial upgrades since the last time I saw him. I hope he liked what heard. I also gave him the earthquake experience 4 x 18" long throw woofer driven by a 2000 watt per chanel and a sweep from 1hz - 100hz Tate could chime in on the experience. After he left I decided a movie night would sound fun with the 2/2000 but with that I had to go in and re balance the output levels and distances (didn't want to screw around with Audessey) so my trusty analog Radio Shack meter got the main duty. Normally I keep the crossover for the subs at 80hz as it allows for a smooth transition between the mains and woofers. But I was very curious if maybe 100hz would make the presentation a little livelier.... The movie: The Accountant Ben Affleck plays a high functioning autistic accountant with some very special skills, he's a mathematician of the highest order and with that he's accounting skills are highly sought after by the bad guys. One of he's special skill sets are weapons, but mostly a 50 caliber Barrett which if you are familiar with the weapon is an amazing killing machine. I like my movies loud and dynamic, and last night it clicked. The first shot out of the gun literally shock my core the air pressure and and the physical effect on your body makes for a very real experience (if you ever been next to a large caliber weapon when it's fired) you know what I'm talking about. The 2/2000 took every thing I threw at them coming very close to 1kw power in the peaks. A little bit bit of tweaking helped the speaker a lot, one thing that I didn't try was adding an 1/8" layer of Sorbothane between the cabinet and driver and with that de-couple the drivers from the cabinet. That would most likely enhance the midrange a tweeter tremendously . Im also curious what some more filler would do as it would prevent aback wave from the bottom of the cabinet..... So many questions, with so many outcomes......... 🇸🇪 |
Good evening everyone.... Should be in Sweden, but decided to wait a few weeks as my dad is out of the hospital and doing a little better. It's always great to see Tate, and we got some time to chat and listen to some great music. As for the 4/5000's I got so far as cutting the bottoms out, strip out all the braces etc. So the BIG question is were am I going from here? Slapping in some braces and call it the day will not happen on my watch so it will be something wild and esoteric (within reason). I need to dampen down the cabinet as it rings like a cheap bell. So the walls will have a multi layer construction (CLD) with a mix of soft pliable glue/butyl rubber layers, and epoxy infused cement. All the mixes and layer choices will depend on how much I can move the frequency band to a desired point were it will sound proper. The top part of the speaker will have a constraint layer of (see image) aluminum, steel, butyl, and 3/4" thick layer of aluminum (I might change my mind about that) the Walsh driver will be counter sunk in the plate. This next part is a trick one as I don't want to use bolts/screws, I want to use neodymium magnets on the cabinet side and on the Walsh driver side sandwiched between some low shore hardness iso-gel. The idea is to totally isolate the driver from the chassis. I finally figured out the bracing system. It will be a mix of a special plastic with constraint layers of a harder layer on each side with butyl rubber sandwiched in between. The deal is that it's very easy to damp to a certain level, but at some point the vibrations have to be dissipated somehow. Kind of how you would damp a tuning fork with your finger. The bottom will have a familiar pattern of a skyline diffuser to try to mitigate reflexions back to the driver cone. To tune the port I will have a sliding tube system that can get tuned on the fly from outside the speaker. I attached a few images showing a waterfall plot of some different materials for bracing (guess which one I'm using). Plywood with a butyl rubber layer, I knocked on the butyl for both samples. Plastic composite butyl rubber Empty cabinet Upper metal rings on a CF plate I might use https://www.flickr.com/photos/147883144@N08/shares/89Wt27 |
So finally passport in hand and a schedule of departure..... Today I was testing some glues, in this case a glue for the end of the cross braces. Super glue sucked, but I'll try a different kind tomorrow. Gorilla glue was promising but not perfect, but the winner was the lowly hotmelt glue....lol More testing to tomorrow as I will most likely use 3-4 different kinds depending on material or if there's a sheer force in the part. Anyway more to come soon....🇸🇪 |
Greetings from a very rainy and windy SoCal... :( Yesterday was incredible here, warm, sunny, and blue skies, perfect for working on speakers...lol The speakers were cleaned from old hotmelt, staples and assorted old crap, but it's amazing that 40 year old particleboard is still staying together and doesn't crumble. I made a test patch of a mixed materials including non drying clay, butyl, cement board, neoprene drenched in a glue that dries but stays gummy and a commercial vinyl tile that is very dense and non resonant. To top of the sandwich I added a 1" layer of felt. The size of the sandwich is 7"x 12" and the final weight was about 4 lbs . The mix of materials makes for a non-reasonance composite. But I am considering adding a thin layer of lead on the speaker walls before the the cement board to make it even less resonant. The final weight of the wall material will be in the 75lbs😜 range including the lead layer. These measurements will change as it doesn't include cross bracing, final top and bottom caps. I do hope to keep the final weight of the speaker below 150lbs without the base that weighs somewhere north of 65lbs. The cabinets were never torn down as far as I can tell, so I re-glued all the corners with gorilla urethane glue, interesting stuff that gets activated with a damp surface or a spray of water. The first layers of metal plates making up the speaker attachment where glued and clamped in yesterday. Basically I took one steel plate attached it on the surface below the original attachment surface. The other layer above the that plate is a 1/4" cork layer a 3/4" layer of particle board, butyl and another 1/4" steel plate. All the layers where bonded together with Gorrila glue. To top of the cabinet / Walsh attachment two more layers of 1/8" aluminum plates will be bonded with more high viscosity glue and then bolted together with counter sunk bolts at each corner. The baffle for the Walsh driver will be about 2 3/4" thick when done.....wow I have questioned the switches in previous posts, so yesterday I removed the the back plate of the switch so I could get to the guts of the part...!! Yes my concerns were all found true, the switching armature is so thin so it's a wonder that they don't blow up all the time, plus it looks like they're made from steel (I will check with a magnet next time I'm out in the shop). Thats today's post.......🇸🇪 |
Another sucky day in SoCal, cold but no rain here in Lakewood.... Woke up up with another palm tree broken at the root, this is the second one in less than two weeks. Figure a few hours in cold shop would do me good, and by the end of the day I had basically installed all the metal plates in the upper part of the cabinet. All plates have either a layer of butyl or a mix of butyl and neoprene rubber and to hold it all together I'm using Gorilla glue. This glue is pretty amazing stuff wet it and it slowly filling any voids and giving the layer a cushion to float on. After the layers were glued together I figured I would do a knock test to see how the cabinet respond to being shored up in a proper way. Check out the before and after sound and vibration test... https://www.flickr.com/photos/147883144@N08/shares/0L3pb1 I should have some more stuff tomorrow..........🇸🇪 |
Back again... Some more thoughts on the build. This morning after a nice cup of joe (or two) the thought of materials and the cost associated with said purchases crossed my mind. I was looking in to plate Aluminum and each plate would cost me a minimum of $300 ( 12"x 12" ) before machining and anodizing/powder coating...Its doable but incredibly expensive in the whole scheme of things. So what can I do to make this a project that someone else could do without breaking the bank? It could also be more fun to figure out a better but cheaper way around the problems. I will have more in a few hours.....🇸🇪 |
The top plate is growing in complexity and thickness, more layers, more damping and by this point I would call it bullet proof... As you can see in the image I made a layer of clay ( yes yes I know it's colorful ) but my supply company had a super deal on the colored ones and it's free of sulfur so I can add silicone in the mix later. To lock in the clay I used some carbon fiber sheeting I had sitting around and to dampen the sheet I'm using the checkered neoprene which allows glue to saturate both sides and dampen the interface with the steel and aluminum layers. Tomorrow will be the first day for bracing.....yeehaa I was going to use some CF material I have left from another project, but it would take some extra time and money as the plates needs to be cut with a water jet. The idea would be some material that can be bored with a forstener bit and possibly jigsawed making it easy and fast. So Im stoked and excited as my ideas are coming to fruition, and who knows it might sound fantastic when all is said and done... check the images out, before I install the Walsh driver I'll add a layer of foam over the CF to quell any reflections. https://www.flickr.com/photos/147883144@N08/shares/996oGG Now I'm going for some Tylenols........🇸🇪 |
Its 2:30am and I can't sleep...oh well After considering the type of cross bracing I want to do, I thought to my self, what's hard, stiff and easy to machine? Got to be easy to cut, glue and cheap. I was going to use Finnply, great stuff, looks gorgeous when finished.....But really, the idea was to utilize less expensive materials in the cabinet that can be found at HD or Loews. So I will use this tempered underlayment 1/8" thick hard as nails and stiff.....PERFECT. I'll make a sandwich construction of the board and a mix of different soft materials, it'll be easy to cut, drill and shape with a router. I did find some aluminum extrusions from another project in the back so I'll use that for corner bracing (why not it isn't costing me much). Any way back back to sleep......🇸🇪 |
After a few cup of Joe's.......I'm up The problem with being semi-retired is that I have way to much time on my hands, I'm not complaining or bitching about it, but My mind I kind of welded to the project at hand and with that nothing else gets done. So in the middle of the night right after the last post I had an idea. You see the image of my vacuum pump for composite work....You can see were this is going lol Damn I really wanted to shy away from the expensive stuff, but a few layer of CF won't kill the project money wise, plus working with composites is fun as you can make shapes that otherwise would take a rapid prototype machine or a five axis machine to produce. There might be more this afternoon, but I need to get stuff ready for the Sweden trip later this week. Here is my vacuum pump. https://www.flickr.com/gp/147883144@N08/59ujV5 Hej då......🇸🇪 |
Greetings from a gorgeous day in SoCal... With my Sweden trip approaching in a few days I'm running out of available time for fun stuff like working on the Ohms.... After the CF ring was installed I did have one more layer to go and that was today's one hour project. The layer from top to bottom contains everything from Butyl rubber, 1/8" aluminum, 1/4" steel, neoprene, 2 types of glue, and finally some 1" felt as you can see in the image (8 layers of metal). The last layer was compressed and glued together with Gorilla glue. If you look closely you can see the the compression bolts pulling it all together. There is also an inside thick layer of non drying clay, neoprene, CF and Gorilla glue bonding the layers together. WOW I know it's a lot but I do want the Walsh drive to be on a super inert 2 3/4" thick surface, no bad vibes....lol https://www.flickr.com/gp/147883144@N08/277b0L The second image is after the compression screw were installed. These will be replaced with real bolts and then Loctited with the red stuff and a big blob of epoxy to lock it in forever. https://www.flickr.com/gp/147883144@N08/F7mV30 The third image is the first of the cabinet reinforcement puzzle. the first layer is the checkered neoprene which allows the glue to wet through the layer and subsequently stick to the inside wall. The thicker part of the part is cement board, totally dead and great to work with. https://www.flickr.com/gp/147883144@N08/56r210 Fourth image is the part installed on the inside wall, you can see the Gorilla glue expanding which is great as I will know that the glue is filling up all nooks and crannies:) Removing the expanded foam does take some elbow grease, but a sharp chisel and some acetone will take care of it. To keep the part from floating away you do have to clamp the piece down. https://www.flickr.com/gp/147883144@N08/56r210 The idea to keep standing waves waves from building up in the cabinet I will stack the surfaces in an unusual pattern allowing the surface To avoid it as much as possible. The edge of the part is were the first horizontal brace start. It will be built up with hard board honeycomb and carbon fiber. Attached will be a special secret sauce aluminum extrusion that will be a vibration damper attached with a very low shore hardness silicone ;) The difference between stock cabinet and the new layers attached is amazing. A thud and no ringing is very exciting indeed. Here's the cabinet knocking from inside out... https://www.flickr.com/gp/147883144@N08/90Dku7 Here's the new layer I knocked on... https://www.flickr.com/gp/147883144@N08/2dk21o More to come and Im loving it.....🇸🇪 |
So the first 4" layer is complete, but not finished. The opening for the Walsh driver is precariously close to the edge of the side wall build up so now I have to make a decision if the I can make the material intrude past the sight line of the driver cone, or the option would be to utilize a softer shapable material.....Hmmm So what should I do? A few options contemplated is leave it alone add some polyester fil glue it in and make it a day..... Or use a material like "Blackhole" to dampen the sidewall surface. I could shape the foam surface a bit so I have a gradual slope in to the cabinet. Lots of ideas in my head, but I would love some input. throw it at me nothing will be discounted unless it's really stupid stuff like depleted uranium, quantum dots and elk horns for bracing...🤓💯 Tomorrow will be tight as I'm leaving for Sweden on Saturday but part of the first horizontal layer is layed out, and all I have to do is making sure the exact dimensions are finished so I can start the CF layup and bagging as soon as I get back.... Bättre brödlös än rådlös.......🇸🇪 |
The final piece before vacation.... This is the beginning of the horizontal plates, each level will have a different pattern and different size holes, all to prevent standing waves inside the cabinet. There will also be a fair amount of vertical bracing all to make the stiffest and least resonant parts.... I do have a fair amount of knowledge from the automotive world and with that I like to apply some airflow management to the surfaces. Don't want to give away my ideas yet but I'm sure you will like my ideas. The image shows the plate with some aluminum bracing, I might or I might not use the bracing we'll see when I get back. https://www.flickr.com/gp/147883144@N08/Th8wcv Anyway that's it for now...🇸🇪 |
The Sweden trip.... Is there a better place but on an airplane to think? I don't think so, but again there's not much to do, unless your next seat neighbor wants to chat away. After a few pleasantries I started to think about the project. Could there a better approach or should I just go with the pre-planed ideas? .........Nope my brain is going as fast as the outside vista is flying by at thirty five thousand feet. There are many questions, should it be stiffer, should it give some, might it be better to have layers that absorb but gives a bit? Is there a way to delineate layers, sections, or should the layers have separate pockets of dissimilar materials so it can be dampened in a horizontal plane. The solutions what ever they are, will ultimately change the character of the speaker. I will come back to these ideas, but I like to give aerodynamics a thought. Does hard, or soft surfaces change how air is pressurized through the cavity? Would it better to make the surface uneven preventing reflections? It wouldn't be to hard to give the surface a mini skyline effect. That could be a good idea in the first cavity as back scatter in to the Walsh driver would be deleterious to the sound quality. Does adding filler or sound deadening materials minimize the air cavity interaction to the Walsh driver ( the answer is yes but how much is the question). Will a smooth surface build up boundary layers ? I guess at this point (in the plane) a simulation ain't happening on my iPad unless there's a CFD app available...... lol. So if you took the speaker cabinet closed of the top part with a plate and some sealer, I would use a shop vacc in reverse, a speed controller could be electronic or a simple restrictor plate. A led light inside the cavity, small tuffs of yarn taped to the surface and finally a bore scope so you can see how the air flows between the stiffening layers. Will the shape of the holes in the plates impinge or add to the flow? Would a convex or a concave surface change anything? Should the holes be rounded over, or is a sharp break in the surface better? By changing the flow over the surface will the vent tube efficiency Increase, or decrease? Would vortex generators break up the boundary layer?? Will the change in the boundary layer give you better sounding or tighter bass? As you are changing the efficiency of the tube will it be possible to change length, ID, or shape. Is it possible to up the efficiency by utilizing the "Coanda effect" by proper shaping.....??? Back to the science of minimizing vibrations, in the horizontal layers/dividers. Each divider sections (as seen in my latest pictures) is made up of dissimilar materials hard, soft and dense. All this to prevent the speaker from leaking out sound that can throw of imaging and proper sound staging. Right now the section is built up of neoprene rubber, glue and cement board. Next layer will be a lead sheet only 1/16" thick glued in with epoxy on top of the cement board. The first layer of horizontal bracing butts right up to this layer and I have not decided if decoupling the vertical wall from the horizontal brace would be important or not, but I'm leaning towards......yes and no! I am thinking that I will cover the vertical walls with E-glass and CF (On top of the lead sheet) and at the joining surface of the horizontal brace I will use a high shore hardness rubber that will be covered with composite. This will Allow me to have a stronger joint between both surfaces. The horizontal brace will be vacuum bagged allowing a much stronger part. At this point the plan is to use a layer of hard board (as per last image) urethane foam board, E-glass with micro-balloons and CF, the CF will be stacked and clocked for high rigidity In compression. I will also have vertical CF standoffs were applicable. The vertical surfaces are harder to vacuum bag, but by using a bladder that expands in the cavity it will simulate vacuum bagging but in reverse and it works incredibly well. Sorry about the length of this post, and I hope someone is reading these thoughts and if not.......Sad! 🇸🇪 Just a pretty picture from somewhere over Iceland... https://www.flickr.com/gp/147883144@N08/rv8j9y |
Thanks Bondmanp..... Just come home to my home away from home in Örebro Sweden after a delightfull lunch with one of my brothers. I was seriously thinking that moving here would be a strong option in the not to distant future, but Being away for 35 years has made me more American than Swedish in so many ways. I will order up composite and lead metal supplies in the next few days so I can get started with the next phase in the buildup as soon as I get home. For you guys who reads my musings thank you, and I promise that more exiting stuff will be forth coming soon.... I dag är det Fet Tisdag så vi ska äta semlor i kväll....🇸🇪 |
Back fro back from Sweden.... Cold, snowy and the best coffee and cakes ever. So I've been working on the project for a few days and I realized that I need a break from posting. I love it but it's been a year since I had a small stroke and I do get exhausted quiet easily from physical work. The project is going forward but I will not put any extra pressure on my self to finish the project. t8kc has been a great guy to let me use his speakers, and I feel lucky to have met one of you guys on the forum. So what next? I will be working diligently on getting the project done, but with a little bit less pressure from my self. As soon as I have something exciting to show I promise you'll be the first to see. For now.....🇸🇪 |
Back in the saddle.... Didn't really jump out of the saddle, but needed some breathing room and some away time from Audiogon. I did take some time to re-asses life IE. I watch a crap load of YouTube videos, a few trips to the fridge, and a lot of napping. And I also realized that I can have a triple espresso and take a nap no problem... So what about the Ohm's? Come on people you didn't think I would give up after all that work...Did you? Between the naps, the snacking and coffee breaks I been very busy working on the speakers. I finally got to the point were it's looking nice inside the cabinet. Yes all the horizontal layers are done, and I used a large sheet of CF on the inside to stiffen up the mid line of the the cabinet. To add even more stiffness, two horizontal bolts were pre-tensioned between the CF sheets and locked in with epoxy. At some point I realized that if I had no idea what specs the Walsh driver has, I would be up shits creek and all that work would be for nothing. So what to do? As luck has it I was doing some Googling on the internets one night and Voila'..... I found the driver and with that all the specs, lucky me!! The next step will be to build a vent tube, yes, yes, I now I could just re-use the original 13" tube that came with the speaker, but what fun would that be? So I'm stepping it up and I will try something different, and it won't be round. I might also add 3/4" MDF on the outside of the cabinet for even better sound deadening (unless the whole thing weighs to much). More coming very soon.....🇸🇪 https://www.flickr.com/gp/147883144@N08/96v0jV |
Heavy speakers.... So the weight is adding adding up fast, and then I decide to make them heavier...!! So after a few days of pondering design, shapes and other life altering decisions MDF krept in to my conscience again. MDF is great stuff, easy to cut usually flat and easy to finish....but dusty lol. So I decided to change the shape a little, I want to add a taper at each corner (as you can see in the image) the outline is the blue tape as a visual. I will add two layers of 3/4" MDF so the bevel/taper will be a little bit more aggressive than in the image. I think by giving the cabinet a few more angles, the design will perhaps be more modern and hip looking. As I said, it's getting heavy........🇸🇪 |
Shapes, shapes...?? Another day and another thought..... So as you can se I did some "Thinking" and the shape has changed as fast and as many times as I've taken showers. So today I decided that the faceted design is the bees knees. I got MDF in my shop, plenty of glue and drywall screws. The shape will be very "Jewely" chiseled and more shapely. I do like the truncated pyramid look, but it's getting a little old, so changing the shape could be exciting. As you can see I roughed out the top with some square wood pegs just so I can have a visual, not necessary a final look but close enough. I will go with a new ribbon tweeter I found, check it out... http://viawave.ru/ The woofer port is another "many shower" issue. I have played around with the idea of keeping the tube I would just compensate for the interior volume. Rectangular port, and finally a passive radiator (PR) on each side of the cabinet..... I might take the leap going with a dual PR set up (2x12") well see and I need to decide which direction I'm going before I start to cut my MDF tomorrow. The cool thing with the PR is that you can tune the port by changing the weight of the cone and spider. The other positive is that I will have less height of the cabinet as I don't have to worry about the bottom port... That's it for now......🇸🇪 https://www.flickr.com/gp/147883144@N08/N98Hn0 |
The right tool..... so having a table saw that decides to never, ever let loose of the old blade sucks but its my main cutting tool, not up to the level I use to have in my cabinet shop but the one I have. Finally I said screw it, I'm going tho spend some cash $$$$ and get a great saw and ladies and gentlemen, I got more done today then I had in my last three. MDF is a bitch to work with if you hate dust. First layer of MDF is on the speaker, tomorrow the second layer will be all ready to go by early afternoon. The thing is like a neutron star, some serious weight, and thats without a Walsh driver, 2 passive 12" woofers and the tweeter assembly. I think we'll be closer to 200lbs. So I'm building a platform with wheels so I can rotate the assembly To cut the faceted 'areas on the cabinet. For a good start of the day have an espresso or two....🇸🇪 |
