Newman Posted July 10, 2017 Share Posted July 10, 2017 @Dave, You know me well and predict my reactions with precision. [emoji16] Link to comment Share on other sites More sharing options...
acg Posted July 13, 2017 Author Share Posted July 13, 2017 My 9yo son says to me this morning: "Dad, I think that when you and mum are really old and I am visiting you in the nursing home that you will still be working on these speakers" 7 Link to comment Share on other sites More sharing options...
Rob181 Posted July 13, 2017 Share Posted July 13, 2017 So wise for one so young.... 2 Link to comment Share on other sites More sharing options...
Newman Posted July 13, 2017 Share Posted July 13, 2017 It's good that he thinks you will live long enough to make the nursing home and not crushed by them falling on you while trying to get a Christmas decoration on top. 4 Link to comment Share on other sites More sharing options...
acg Posted July 25, 2017 Author Share Posted July 25, 2017 I've stopped counting the hours that I have spent on all this steel work. It is a lot. Far more than I had anticipated but I can see the light at the end of the tunnel now. Some of the steel is getting a light surface rust even though I oiled it and I really needed a big push to get the next round of steel to the powdercoater. So I took a week off work and did little else but steel. It was needed. Yesterday, I finally got the pair of DSET amplifier chassis' all put together...have a look below... The one on the left is viewed from the front and the other is viewed from the bottom. From the back (excuse the greasy paw prints)... ...and from the top... The outer panels are all 4mm steel and the top plate is 8mm aluminium. The whole thing weighs 55kg and once the CLD is installed it will probably extend to 75kg...then I have to stuff it with components which will take it to around 110kg. The base plate (below) is 10mm steel and you can see three recessed 50mm diameter circles where the horizontal isolation will be installed i.e. the upper plate of the ball bearing thingamy I posted about a while back. There are holes for two computer fans that will push air up through the chassis which will exit around the base of the tubes. The umbilicals from the DSET power supply will also enter the amplifier via the base plate. Another view to show the depth of the skirts and the 10mm bars that I have welded on them as an anti-vibration measure. CLD panels will also be applied to these skirts but I thought they could do with some extra stiffness. Notice the 'enclosed box' at the top of the previous two photos. The active crossover filter for the RAAL Ribbon will be installed in an aluminium box with RFI shielding which in turn will be placed in the 'enclosed box' of the previous two photos. The 'enclosed box' is 4mm steel which hopefully will be enough to shield the filters air capacitors from internal magnetic fields as well as the significant magnetic field that will emanate from the DSET Power Supply that is a short distance away in another steel shielded box. When assembling or tweaking the amplifiers I can take off whichever external panels are necessary to expose the relevant bits. Below is a view from the top. That weird shaped rafter plate will hold the tube sockets among other things and as you can see below it sits on 'pillars' so as to maximise access to the spaces underneath. The 8mm aluminium top-plate sits on top of this thinner rafter plate and the two screw together which greatly increases the rigidity of both plates and hopefully will work well with the reasonably microphonic driver tubes that I am using. It's not complicated in there...nah... There are three aluminium platforms for output transformers that are isolated via sorbothane bushings. Additionally, all amplifier internals are aluminium so as not to be induced to vibration by the magnetic fields from the OPT's. All external panels except the top-plate are 4mm steel and I went for an 8mm aluminium top-plate partly for additional shielding but also because I need to machine some channels in the underside to direct airflow. From the front you can see (below) four pieces of thin aluminium angle with holes. These holes will accept potentiometers and switched attenuators. The idea here is that to remove the external panels through which they poke all I have to do is remove the knobs, unscrew the panel and then pull it off. If the pots etc. where actually attached to the external panel it would be a nightmare to get that panel on and off with 8 shafts to hold and align while trying to line up screw holes. Here is another view from the side... Today I will pull down these chassis', tidy up some edges, make sure the countersunk holes are correct depth and the parts will be ready to paint or powdercoat. Huzzah! 2 Link to comment Share on other sites More sharing options...
Rob181 Posted July 25, 2017 Share Posted July 25, 2017 Not over engineered at all....nooooooo..... Link to comment Share on other sites More sharing options...
shaky Posted July 25, 2017 Share Posted July 25, 2017 Like one of those 500 piece adult aged jigsaw puzzles. Too complicated for me. Bloody nice work. 1 Link to comment Share on other sites More sharing options...
aertex Posted July 26, 2017 Share Posted July 26, 2017 Anthony, I know it is an extremely inappropriate rude question...but where are the $$$ heading on this project? Are you working to any figure particularly? Very good stuff though anyway cheers Alan Link to comment Share on other sites More sharing options...
acg Posted July 26, 2017 Author Share Posted July 26, 2017 (edited) 1 hour ago, aertex said: Anthony, I know it is an extremely inappropriate rude question...but where are the $$$ heading on this project? Are you working to any figure particularly? Very good stuff though anyway cheers Alan I'm not keeping track of the $$, but it is not inconsiderable. There is no budget but the benefit of doing it all myself, or the great bulk of it anyway, is that the project is slow and in the interim I turn over a fair swag of income of which a little is poked at this project. Also, by designing it myself I am able to bias the build towards lower dollars and higher labour. For example, these 6 channel amplifier chassis' are going to cost me about $1.5k for the pair and a whole lot of labour. If I went for a low labour design I could easily quadruple that dollar amount. Likewise if I shunt a heap of steel at the powder-coater the price comes down dramatically so I send things in big batches. The things that I am not doing myself I get quotes for and pick and choose among them. For example this last batch of steel that I had cut for the horn stacks, equipment rack, vibration platforms and amplifier chassis' would have cost about $6k if I chose any single cutting firm but I had the whole thing split into 6 jobs and chose the best price for each of those jobs and all that steel cutting (including the steel) cost $4k. That's a big saving right there. So, for $5.5k I will end up with the following articles completely painted and finished: equipment rack; 4 x vibration isolation platforms; horn stack; 2 x 6 Channel amplifier chassis'; half of the Bass Cannons. That's ripping good value by any measure but it means a lot of work for me. Edited July 26, 2017 by acg forgot the bass cannons! 2 Link to comment Share on other sites More sharing options...
acg Posted July 26, 2017 Author Share Posted July 26, 2017 4 hours ago, shaky said: Like one of those 500 piece adult aged jigsaw puzzles. Too complicated for me. Bloody nice work. It will be a 500 piece 3D jigsaw puzzle by the time the amp has glowing bits on top of it. Link to comment Share on other sites More sharing options...
aertex Posted July 26, 2017 Share Posted July 26, 2017 Anthony, thanks for sharing some of those outcomes and numbers. It does help the interested psectators like myself and many others no doubt. I think that although the scope of the DIY works you are doing would not be easily possible for most on SNA, when the $$ are thrown in, the picture is appearing to look favourable relative to what a retail price would be for your system-which would have to be horrendous and would be that close to 6 figures, it wouldn't matter Alan Link to comment Share on other sites More sharing options...
Silent Screamer Posted July 26, 2017 Share Posted July 26, 2017 What no cross bracing, is that going to be stiff enough? 1 Link to comment Share on other sites More sharing options...
acg Posted July 30, 2017 Author Share Posted July 30, 2017 (edited) Yesterday, I had the pleasure of meeting fellow SNA'er @Silent Screameras my son and I trekked down to Ipswich to give Paul and his CNC a visit. For those that don't know Paul has this epic CNC build and has only very recently managed to evolve the machine to its current state of 'high performance' as he gradually built some of the last parts with aluminium rather than the initial plywood. I love the idea of a machine that builds itself i.e. build it first with ply and then slowly use itself to replace ply with metal in the process becoming more precise and close tolerance. The machine appeals to me because of its obvious elements of 'over-engineering'...something to which as a farmer I have been indoctrinated and have gravitated toward in the build of my own acoustic system. Pauls progress with the machine seems to be at the threshold of 'ready to be finished' with relatively small details to be completed and a few minor functional aspects changed, but it is strong and precise and eminently useful: those finishing touches will take quite a bit of time to actually achieve, so there are still plenty of hours left in the project. Here is Pauls CNC at work in the first of the top-plates... ...with it ready to be unclamped... ...the second plate also finished (note it is a mirror of its partner)... So why did I need this CNC work? Have a look at one of the finished top-plates below. The top-plates for my DSET amplifiers are 8mm aluminium. They act as both a facade and structural element to increase rigidity and as an important element for the cooling of the amplifiers. Two 80mm PC fans are attached to the floor of each amplifier that push air up through the internals and then it exits around the valves on the top plate. Most of the heat generation will be at the valves...those 6C33C burn at 350C or thereabouts and I have three in each amp, plus a bunch of closely spaced smaller tubes. Lots of heat! Anyway, the rafter to which the valve sockets attach is actually screwed to the top-plate when the top-plate is in place and I needed a way to give a low impedance pathway for the airflow to get past the rafter and evacuate through the holes in the top-plate. Notice that the CNC has been used to machine 4mm deep recesses around the holes in the top-plates for the valves. If I then place the rafter in the position in which it will be bolted to the top-plate then you can see that the 4mm recess that the CNC has made will allow airflow around the top of the rafter. Job done. Thanks Paul! Edited July 30, 2017 by acg 11 Link to comment Share on other sites More sharing options...
Silent Screamer Posted July 31, 2017 Share Posted July 31, 2017 Cat's out of the bag now... no more procrastinating for me, now people are going to expect to see some long promised speakers from me 6 Link to comment Share on other sites More sharing options...
Upfront Posted July 31, 2017 Share Posted July 31, 2017 Yep! Link to comment Share on other sites More sharing options...
acg Posted July 31, 2017 Author Share Posted July 31, 2017 Sure will Paul! I'll look on with interest. 1 Link to comment Share on other sites More sharing options...
Rob181 Posted July 31, 2017 Share Posted July 31, 2017 As do we all.... Link to comment Share on other sites More sharing options...
acg Posted August 1, 2017 Author Share Posted August 1, 2017 It's like deja vu. Painting the internal amp parts that won't be powdercoated, stuff hanging of the clotheslines, a rope line strung between the jacarandah and mulberry trees with more stuff dangling in the breeze. The 10mm aluminium posts have been brushed and clearcoated so they look shiny and pretty. Tying the knots in the cotton thread to hang these suckers took an entire album to complete with my man hands, and was probably one of the most soul destroying things I've done for the project thus far because I had to resort to tweezers in order to make the knots. I mean, how hard is it to tie a couple of granny knots in some string? Pretty hard if your name is Anthony. 3 Link to comment Share on other sites More sharing options...
BioBrian Posted August 2, 2017 Share Posted August 2, 2017 Some people pay a lot of money for artworks as good as that! 1 Link to comment Share on other sites More sharing options...
acg Posted August 3, 2017 Author Share Posted August 3, 2017 Thought I would share the initial results of the Cannon ringing experiments. I've recorded the ringing of two individual bass cannons (one with no automotive deadener applied; the other with deadener applied) but I can't figure out how to attach the audio to this post so you will just have to believe me I guess. It was a simple knuckle rap test where I hit the outside of a cannon with my knuckles (one of which is now swollen - I must be a bit soft these days) with considerable force and then recorded the decay or ringing. The untreated cannon audibly rang for about 20 seconds; the treated cannon rang for a touch over 1 second. A good result I would say, considering that this is without any bracing and I fairly slammed the steel with my knuckles. Next I will add the external bracing, which previously made a tremendous difference to the untreated cannon (it rang less than the treated cannon did this morning) so fingers crossed I will have a suitable result and can then move on to acoustic testing. Link to comment Share on other sites More sharing options...
Silent Screamer Posted August 3, 2017 Share Posted August 3, 2017 A touch over a second is a serious reduction but at the same time it is still a fair amount. Hopefully the external bracing reduces that even further, but do you have a plan B in case it doesn't enough like perhaps coating the outside? Link to comment Share on other sites More sharing options...
acg Posted August 6, 2017 Author Share Posted August 6, 2017 On 8/3/2017 at 8:04 PM, Silent Screamer said: A touch over a second is a serious reduction but at the same time it is still a fair amount. Hopefully the external bracing reduces that even further, but do you have a plan B in case it doesn't enough like perhaps coating the outside? It is a fair amount but from another perspective it is not. I have since performed the test on a couple of other things about the place in order to get some sort of a baseline. Double brick wall - 0.7s ringing time Lenehan ML1 - 1.0s (top panel) and 0.8s (side panel) The ML1's are solidly made and quite inert as far as cabinets go, but depending on where I hit it it performs somewhere in between a massive brick wall and my damped but not braced cannons. I would like to think that the bracing will lift the performance of the damped cannon to somewhere near that of the brick wall. That is my aim. Link to comment Share on other sites More sharing options...
Rob181 Posted August 6, 2017 Share Posted August 6, 2017 I hope it will sound a lot better... We don't need another brick in the wall.... 2 Link to comment Share on other sites More sharing options...
Silent Screamer Posted August 6, 2017 Share Posted August 6, 2017 (edited) I guess everything has a natural frequency duration, so to eliminate it entirely is an unrealistic ask. Except water... knocking on water exhibits no perceivable resonance, only wetness. Edited August 6, 2017 by Silent Screamer 1 Link to comment Share on other sites More sharing options...
Pops110 Posted August 6, 2017 Share Posted August 6, 2017 Great work mate. I would imagine that once all of the bracing is on the cannons and they are all together it would eliminate most of the ringing but you could also experiment with with different sorts of rubber/foam etc wedged in between the cannons and also at different spacing along them. May take a little of the aesthetic away but could be worth it. Cheers Dave Link to comment Share on other sites More sharing options...
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