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acg

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acg last won the day on March 25 2018

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About acg

  • Birthday 31/07/1973

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  1. You don't need to be too careful. It cuts easily with scissors so long as the blades are wet. If you have bubbles on the first layer then you can just use a stanley knife to open the bubble and then squeeze out the air with the roller or with your fingers. It is vicoelastic so any holes you make in it will eventually self heal. I usually affix the DIS8 to the thinner bit of metal first, roll it down well, pop out any bubbles, and then align it to where it needs to go on the second bit of metal keeping it a centimetre or two separated and then push/drop it slowly into position. You can lift it off if no pressure has been applied and if not too much area has made contact but once pressue is applied you will have trouble removing it so get it right the first time. It used to be on their website and I am sure they would forward it to you if you asked. Dis8 is designed for steel/aluminium or similar metals. A thin metal of preferably a different type should be used to damp the main structure, in your case the shelf. 1mm aluminium works really well with 4mm mild steel. 2mm aluminium is better for thicker steel. You never want anything sitting on the dampening sheet (aluminium) because the pressure will push the DIS8 out the sides over time and make a bit of a mess. My shelves are 10mm steel and I use DIS8 and 2mm aluminium underneath the shelf where nothing touches it. Have a look at the photo: You do not want any weight on the DIS8 other than the aluminium sheet otherwise it will not work as well and may make a mess. It's purpose is to make the steel shelve not ring when excited...not to hold up your components. Just measure off the shelf below or above with a tape measure. Or if you really want to use a bubble. If using Bunning grade material then I would look at ceramic tiles, especially any porous ceramic tiles. Ceramics can be excellent at absorbing vibration up to a point...but relatively brittle. I personally would not touch them. The rubber will have a relatively high Fs. Sorbothane probably more useful but with these sorts of things you need to load them properly to achieve low resonance frequencies. I used sorbothane washers/bushes in my amps and preamps where I wanted to isolate mains frequency vibrations of transformers/chokes from the chassis and sorbothane could only just do this if loaded properly with the correct weight. Have a look at this site: https://www.novibes.com/Products I've used the pneumatic mounts, bubble mounts and compression mounts in various places in my system These guys tell you how much weight needs to be on them to achieve the lowest resonant frequency...very useful and good, relatively inexpensive kit too.
  2. The OCD audio side is coming out now. Does anybody know of a box that is: Digital inputs (preferably more than one) Magic foo DSU/DTS/Auro upmixing onboard (preferably selectable by remote) Digital outputs (so I can use my own dacs) Would love to use my own dacs especially for the mains...perhaps not so important for the rears. I can certainly understand that the market would be quite small for such a product.
  3. BB I saw your post last night and was interested but too busy and went to have another look this morning and it was gone...😥 Something about Auro 3D?
  4. Looks like I have a new google search phrase...I really have no idea on this stuff. Will have a look through the Anthem manuals to see what it can do.
  5. Are we talking about distortions in the electronics chain here? If so then I almost completely disagree. Once distortions are low enough, the level of which varies according according to the type of distortion, lowering it further is inaudible. More destructive I believe is the 'race to the bottom' where low numbers are selling products that don't actually sound very good but they have a metric which some people believe will make them sound good. I used to think that when I was playing around with small speakers. I do not think that way any more.
  6. In my opinion, distortion is such an overhyped 'thing' in audio reproduction akin to the fairytales/fables told to kids to encourage them to conform. The word significant is important. For example I think we can listen to plenty of harmonic distortion before we even notice it...levels that are trivial for electronics to better. Speakers though, that is a whole different thing.
  7. @att23thankyou, that is good information. After skimming the Wendy Carlos stuff I think my rear angles are pretty good for the ideal Quad setup but I certainly listen closer to the mains I do listen to classical and would love more ambience from the venue. Likewise with other live recordings. Yamaha used to do their natural sound processors, or something like that name, which would decode and push ambient information from a stereo mix to rear speakers. Something like this may be useful for the stereo recordings that I love...would have to try.
  8. Yes, the decoder, which is what is for me impossible to quantify...is my AVM60 similar/superior/underperforming compared to a Yamaha processor, or a Marantz, or the Trinnov? Who knows?
  9. Many would. But with a closed system such as mine there is no need to be wed to some industry standard voltage level just so it is compatible with other devices. The job of the preamplifier is to be that bridge between sources and amplifiers.
  10. Yes, I could not see a lot of Atmos music that I would listen to on there either, but perhaps it is coming. John Williams would be nice...
  11. However much I dislike linking to this particular website, I recently found a review here that has comprehensively measured them with some interesting conclusions. Horizontal directivity +/-50degrees down to about 1kHz, good power response, keep the tweeter pointing at your ears, starts to struggle a bit at 96dB. I have made up some wall brackets for the JBLs to put them at correct level in the rear corners of the room and to be able to rotate them towards the listening position. When I get them back up on the wall I will have to play around with some absorption on the wall immediately adjacent to them to see if I can hear the difference but they are front ported and do stick quite a ways into the room with that +/- 50 degrees directivity so there may or may not be something tangible. Yes, the big horns are directivity controlled, but not necessarily uniformly, down to perhaps 80Hz-100Hz insofar as being below the Schroeder frequency will allow whereas the JBL's are three octaves above that, well above Schroeder. This does make sense. Where the JBL's sound "loud" is much lower than the big horns which I have attributed to being limited in the bass...but it may be the change in directivity at least partly to blame...very interesting.
  12. @stereo coffeeall components from the horns to amplifiers to preamp to dac to phonostage thus far apart from the surround speakers and AV processor have been built from the ground up by me. My speakers are fully active six way passive line level crossover (PLLXO) 110dB/w/m sensitivity (100dB/w/m for lower bass channel) driven a specially designed 6 channel SET amp on each horn stack. These amps need about 4V RMS input and with the PLLXO present a rigorous 5kR load which most preamps have real touble with so I have built a DHT preamp using type 10/801a tubes that pushes a lot of current, has low output impedance (circa 19R) and provides a x8 amplification of my sources all of which are circa 1Vrms output. Volume control is via high quality autoformer at the output to the preamp which means that as I attenuate the output impedance of the preamp falls rather than rises...a win-win situation. I'll never go back to commercial amplification for my stereo rig and as you can see am very concious about gain structure.
  13. More or less Dave. Will do some more on it when I have time, but what is left are generally room modes which I plan to first try to attenuate with VPR's. I look a the Trinnov processors and how they manage phase and time alignment and wonder if that is the next step up right there. High price of entry though. It is interesting listening to both the horns with their narrow directivity and rubbish power response and the JBL's with their wider directivity and excellent power response and the big horns image soooo much better. Getting those room reflections out of the equation as much as possible really seems to help in terms of image quality. Are you suggesting that narrow directvity surrounds might be a better option? I do have a spare pair of 250Hz and 400Hz horns and spare drivers from the main system that I could hook up but surely that is overkill. The sweet spot for surround listening would be very small.
  14. Brian, I just had a look at the Megasorber site for the measurement specs of some DIS8 applications and they have a new website with nothing useful I could find. DIS8 is meant to be used between two metals of different thickness and/or different type. I can vouch that 4mm mild steel >> DIS8 >> 1mm aluminium is very dead and makes the ringing caused by a knuckle-wrap inaudible. My rack shelves are 10mm mild steel >> DIS8 >> 2mm aluminium and they are not as dead as the first scenario above but once you get weight on the rack (i.e. your components) the steel takes more energy to become excited, which is good because you do have some nice heavy gear. Then, in my individual isolation platforms (which sit on the rack described above) which incorporate industrial pneumatic dampers I needed something very heavy so that the pneumatics are working in their ideal load range with relatively light audio equipment so I went with something like 20mm steel >> DIS 8 >> 6mm steel >> DIS8 >> 10mm steel >> DIS8 >> 1mm aluminium. Certainly got the weight to load the pneumatics with all that steel and if you do a knuckle test on that setup it is completely and utterly dead and your knuckle knows it has struck something with absolutely zero compliance i.e. it hurts. My shelves are all adjustable, and yes I have adjusted their heights several times when shuffling components about, and I used extruded aluminium uprights from 80/20 Aus which have a nice brace and bolt setup for just such a thing. I got the ones with a track on only one side that I face inwards so the brackets cannot be seen and with a nice smooth anodized finish facing the room. Four of these brackets easily hold circa 100kg on each of my shelves so the setup is strong. They threaded mine so that I bolted the top shelf and base directly to the top of the rack which looks rather neat and you can even fill the middle of the aluminium extrusion with sand or granite of something if the OCD really kicks in sometime (I haven't yet, but just mentioning it means I am still thinking about it haha). One thing I always do with the DIS8 is use a small roller to apply a fair bit of pressure and roll/cut out any air bubbles as soon as you see them.
  15. Yes, not many Atmos selections in that list, but it feels as though it is emerging as a music format. I already have quite a few of the others on the QQ list including some that rate quite highly and will have to pull them out again for a listen. They should be and that is why I purchased them. Plus they are recommended as the rear speakers with JBL M2's as the fronts. The JBL's have a waveguide with compression driver and an 8" woofer, front ported with DSP up the wazoo to help all the graphs look correct... and they are set at a good height in the rear corners. But my mains look like this: and make the JBL's sound a little broken in direct comparison. BUT, I have been forcing myself to listen exclusively to the JBL's for the last few weeks with them set up in the room as mains and they are actually quite decent in the midrange and up, a little too hot in the highs but I think that can be fixed if I put my mind to it (on-board DSP). Although their midrange is 'dry' compared to the big horns it actually does not annoy me as much as it should but upperbass and lower, say < 1.5kHz the big horns absolutely cream the JBL's. Although well spec'd especially among others of their type, the JBL's go nowhere near as loud as the big horns before you get uncomfortable with the distortion, but I do honestly think they are near as good as you can get for the form factor. Another plus is that their directivity and power response is excellent and they do sound very similar across the room, certainly much more similar than the big horns, which is to be expected given the topology, which make them very useful as surrounds. Where am I going with this? Well, I don't know how much low frequency information is generally mapped to the rears in typical 5.1 music. How low should those speakers go? The mains are more or less flat to 18Hz in room but I dislike the JBL's for everything upperbass and below so my concern is whether I should augment the JBL's with additional bass driver/s or whether I should swap them out for a good set of 3-ways or whether cutting them off at something like 500Hz will really improve the upperbass enough for them to be useful? Lot of experimentation is on the cards unfortunately. Thanks for this link. I enjoyed the read and learnt a few things.
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