awkwardbydesign

Wammer
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Everything posted by awkwardbydesign

  1. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    Will there be accelerometer measurements* of the effectiveness of these stands? With my quick and easy innertube stands, I found a reduction of about 75% comparing the the top plate of the stand with the floor measurement, using music. I haven't tried it with the sig gen, to see which frequencies are most attenuated. *Accelerometer app on phone.
  2. awkwardbydesign

    Dvdplayer for music is that recommendable on a low budget ?

    I have several DVD players, bought from charity shops. None cost more than £5, and they all sound different. They are in use in the two systems I have in the loft, one being fed into a Xiang Sheng 01A DAC, and the other straight to the amp. Both work well enough to enjoy the music. At those sorts of prices you could afford to try a few and see what you like.
  3. awkwardbydesign

    Magnepan LRS (Little Ribbon Speakers)

    That's not a ribbon, that's a different kind of planar.
  4. awkwardbydesign

    Shame!

    I don't understand it, but I have to use it, as most of my new music comes from downloads. Bandcamp in particular, but others too.
  5. awkwardbydesign

    Heybrook HB3 series 2 response measurements

    Does anyone have a link to the measurements of the old HB3's frequency response? I'm thinking HiFi News may have tested them at some point, or even Heybrook's published figures. I have a pair (well, 2, sort of) and I picked up a cheap subwoofer*, so some numbers would be good. It would be possible, but not easy, to drag them down from the loft and set up a mic with REW. And as they will be used up there I don't know how valid that would be. They can't be used anywhere near a wall, so bass is lacking, and I've never played with a subwoofer, so thought it worth a play. *Mordaunt Short Alumni 9 - £40 so no real loss if it doesn't suit.
  6. awkwardbydesign

    Heybrook HB3 series 2 response measurements

    Thanks, I've seen that one. Some graphs would be nice, though.
  7. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    That appears to give a resonance of 4.76 Hz. with 13kg. Double what I wanted, but still useful. http://hyperphysics.phy-astr.gsu.edu/hbase/shm2.html
  8. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    No argument there, but inner tubes are cheaper and easier, also they can be tuned with different pressures. Plus the same stands can be used for different speaker weights. I did find they were much less effective under electronics, probably because they were too stiff for the weight. This pair I have remade were probably just such rejects. I have been using two bike tubes at a time, with separate valves to achieve balance side to side, and move the speakers back or forward for front to rear balance. They will slowly deflate (or quickly when they fail!), but if I keep an eye on them and re-inflate to the same height they work OK. I have just come in from the garage, where I am making another pair, and the only cost will be for four new inner tubes. £14 posted. Eight springs coat me £80 five years ago, and that was cash in hand. The official price would have been considerably higher. Max's current designs are fantastic, IMO, but too expensive for me, especially as I can make something which will do a fair job. PS. What were the linking pipes you used?
  9. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    If you want to try the inner tube idea, here are some details from my current stands. I use cheap innertubes, as they are soft and seem to work well for this use. This is the make and size I use. The bases are 440mm x 370mm x 50mm, all 19mm MDF. Simply what I already had, with a bit of trimming. Big enough to allow me to move the speakers around on them for levelling. The top plate can be anything; I used what I had, but if the granite I also have had been the right size I might have used that. Each compartment for the tubes is 400 x 140, giving a circumference of 1080mm which fits the tube. If you change the overall size or shape, keep close to that circumference. They are 30mm deep which holds the tubes in but allows the tubes to stick up enough to work. When you have settled on the working height you might want to place some packing pieces, or stick on feet, in the gaps so if (when!) a tube deflates the speaker won't drop too far. Also stops kids rocking them dangerously. Leave some gap (3-5mm?) for normal movement. I haven't bothered, as there are no kids and my previous speakers weren't tall and narrow enough to be at risk.
  10. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    The original Seismic platforms used inner tubes. Not as saleable as the current spring based units, but easier for DIYers, and self damping. You adjust for different weights by pumping them up more or less.
  11. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    Very slightly off topic, but I remade the innertube stands today. I shortened the bases so the tubes fit better, cut a couple of tops (one is MDF, the other is chipboard) and the old tubes still hold air! I had to twist the tubes so the valves are on the outside, and then slide the speakers forwards a bit so the weight is central. They rock slowly and then stop. Hopefully they may reduce sound transmission to the neighbours, but at least I am re-using more of my old stuff. Another project that cost me nothing! The speakers next to them are genuine Heybrook HB3s, which were free apart from the refoam kit.
  12. awkwardbydesign

    How you can still travel about after the apocalypse

    Not too snowflakey; there appears to be nothing to lock them onto the rail, so leaning too far to the right would make life interesting. And short.
  13. awkwardbydesign

    Banana plug stuck in amp speaker post

    Did you examine the plug and discover the cause?
  14. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    Right, I eventually found my original calculations for 15kg, which would be close enough for 12kg. But here are the calcs for a 12kg weight. You would need 8, of course. Using the AmesWeb calculator- https://www.amesweb.info/MechanicalSprings/CompressionSpringForcedBasedDesign.aspx#.U-NL0_ldVN5 I get these numbers. Spring diameter = 50mm Free length = 75mm Wire diameter = 3.25mm Coils = 5.76 total/3.76 active. Spring rate = 2.79 Load at height = 120N (12.237kg) at 32mm Music wire with closed and ground ends These numbers give a stable spring, and a resonance of 2.4Hz http://hyperphysics.phy-astr.gsu.edu/hbase/shm2.html#c1 Using my 15kg springs you would get 2.7Hz with a 12kg load. Either spring would do. But I have just found my old 2 inner tube bases, so I intend to resurrect them for use under my HB3s. https://hifiwigwam.com/forum/topic/133911-electrostatic-hb3s-sort-of/?tab=comments#comment-2394718 and these
  15. awkwardbydesign

    Electrostatic HB3s. Sort of!

    As I have a pair of SEAS 10" drivers, as used in Heybrook HB3s, and some MDF, I decided to make up a couple of cabinets for them. They have been sitting idle since the late '80s, as have a pair of Shackman electrostatic panels, so I thought, let's see if I can combine them! The Shackmans will (allegedly) go down to 500Hz, and the specs on the SEAS drivers look clean up to 3kHz, so I am going to see if a 1-2kHz crossover will be feasible. i already had the MDF cut to size, so £20 for some beech veneer and iron on edging is all I've spent so far. Some old (Cardas?) binding posts fit nicely, and I have grille cloth. I had made curved panels for mounting the Shackmans several years ago, and as long as the 'statics power up I should be good to go. Hopefully! The cabs are now made and veneered, but it may take a little while to complete them, so don't expect daily updates.
  16. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    If they for are speakers, you may struggle with extension, as you will need to make towers to hang them from. As it happens I have just been looking at wheelbarrow tyres, which are available for 4" wheels and bigger. Four of them in a box under each speaker would work nicely, I believe; you just need extension fittings so you can re-inflate as needed. https://www.ebay.co.uk/itm/INNER-TUBE-All-Sizes-Of-Tubes-For-Wheelbarrows-Sack-Trucks-Carts-Scooters/173101022109?hash=item284d9ffb9d:m:m_8FTTq0TE0tfM_MMoECwWA But calculating the spring rate for 45kg speakers is not hard. Just divide by 4, so 11-12kg each, make them 50mm dia and 50mm high for stability, use 3mm piano wire* and Bob's your uncle. https://www.amesweb.info/MechanicalSprings/CompressionSpringForcedBasedDesign.aspx#.U-NL0_ldVN5 Make sure the spring isn't coil-bound when loaded, and aim for about 50% compression. Add friction damping if you like; I used a wadge of speaker foam. Resonance calculator. http://www.efunda.com/designstandards/springs/calc_comp_resonance.cfm#calc 2-3 Hz will do. If you are serious and do all this, I will PM the name of the guy to ask. It would be cash in an envelope, but that worked for me. * That would need to be checked with the spring maker, as they have standard wire diameters, but I think that's what they are.
  17. awkwardbydesign

    Favourite female singers

    Camille Dalmais Rokia Traore Alejandra Ortiz Christine Perfect Norma Winstone
  18. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    The knurled nut is for preload. That sets the ride height of the bike, (or car) to allow the vehicle to rise or fall the required amount for the conditions. On a motorbike (or car) it would be set more centrally for a bumpy road than it would for a smooth track, where there would be heavy braking but less upward bouncing. It won't set the resonant frequency. Changing spring rate does that, which is why I had my bike's race shock built to suit my weight. With the inner tube type, I used two tubes and adjusted them to suit. If I do it again I will use four small tubes (pram? wheelbarrow?) tubes to provide even better adjustment. For a commercial product like Max's, that wouldn't really be saleable, but for personal use I would find it acceptable. BTW, I found the cheapest and thinnest walled tubes gave the best performance; the better ones were too stiff.
  19. awkwardbydesign

    DIY Townsend Seismic Speaker Platform

    https://www.pinkfishmedia.net/forum/threads/speaker-isolation-plinths.171044/ Pictures have gone, mostly. I added some damping, but the speaker leads probably give enough, to be honest. I would have stuck withe inner tube design, but the metal cantilever stands for the top cabinets get in the way. They were self damping but needed re-inflating periodically. I used two in each stand so I could level the speakers. If the mountain bike dampers are urethane, that is what Max used between the inner tube and spring designs
  20. awkwardbydesign

    Electrostatic HB3s. Sort of!

    I am doing all this on a suck it and see basis, so any tips or even basic info will be much appreciated. Such as the inductance/capacitance points raised. I have been running it with a Philips DVD player as a CD player (I have tried several from the local charity shops, and this one sounds the best) into a Tangent Amp 50 (free!), playing Nils Lofgren Acoustic Live. Maybe not the most complex music, but I am reminded why I like non-dome tweeters and sealed box bass. There is an obvious peak (around the crossover point at 1500Hz, comparing the peak on piano with a tone on my phone), but things like audience noise sound very realistic, plus the guitar and voice. And this is with them about 4 ft apart, almost backed up to some cupboards! I have always had trouble with dome tweeters, possibly that pesky 6-8 kHz peak in my hearing, and prefer ribbons, planars and these statics, despite the other problems associated with them. I have never had really expensive domes, just up to about £120, so I might be OK with top of the range domes. If I can get my hands on a subwoofer, it might be interesting, but that's not a priority. Measuring them and adding baffle step compensation is.
  21. awkwardbydesign

    Electrostatic HB3s. Sort of!

    I made up a crossover (I use the term loosely) and fired it up. Or not. The amp wouldn't turn on! There was a 2 amp fuse in the mains lead, which was dead, so changing leads fixed that. Then no sound from the Shackman panels! A dodgy croc-clip lead this time. Eventually it all worked, but a bit honky, so a towel over the back of the panels tamed that a bit. At least nothing died, so I will try both of them with some music before dragging them downstairs for the REW testing. BTW, next door's dog took exception to the sig gen, and started barking!
  22. awkwardbydesign

    Electrostatic HB3s. Sort of!

    I've just measured the impedance of the Shackmans. A 3R3 resistor was added in series (before the trafo), as I know the impedance drops very low at HF. But it seems it also drops low at LF too! Remove 3R3 from all these readings, and you find the impedance is about 1R2 at 200Hz, and 0R7 at 20kHz! The peak at 2kHz will make the crossover design interesting, so I may try for 1st order at 1.5kHz, for simplicity, and measure the acoustic response to see if it works. At the moment I have no idea of the acoustic output of the thing, and the dipole nature of the beast will be interesting! Fortunately the bass driver sits at around 6R5 with the Zobel, but it's natural HF roll-off might affect the crossover point and slope.
  23. awkwardbydesign

    Electrostatic HB3s. Sort of!

    A bit more done. Acoustic foam linings to control internal echoes, and safety backing plates to keep fingers away from the mains and HT section. I can also hang some absorption from that too as needed. Heatshrink around the IEC socket and switch. Red LED added under the grille, so I know when they are powered up! And simple stands to lift them up a bit. Old kitchen cupboard frames glued together to get a usable thickness, threaded inserts in the tops and M6 furniture bolts, to a bit of 19mm MDF. I bought the M6 screws, but I had the rest. I reckon I've spent about £40 so far; they should be worth that in the end!
  24. awkwardbydesign

    Southgate appreciation

    It's curious that the players who made the big mistakes with this system were those who play it every week for City. Admittedly Stones and Delph haven't been playing regularly, but Walker has, and they all struggled. Of course England use a goalkeeper who doesn't play that way, and it showed at times, but still.
  25. awkwardbydesign

    Electrostatic HB3s. Sort of!

    Thanks, I'll bear that in mind (Max's drivers). And the 'static panels work! No idea of quality yet, but after adding a 3R3 resistor in series for safety, they measure around 8 ohms at 1kHz, so I bodged a simple 2nd order crossover at 1kHz (15uF and 1.8mH) to test them. The voltage starts dropping from around 2kHz, and continues down, with basically no output at 200Hz, so at least in the ballpark. But the second panel was silent! Until I plugged the mains lead in. Now I'll have to make similar for the bass units, and stick a rheostat on the panels for level, and see how I go. SWMBO won't like me bringing them down from the loft to test them; she hates the sig gen through speakers, but really it's no worse than some of the music I like! I would like to cross them over lower, but I'm not sure that would be wise, so for now I'll stick with 1kHz. I already have some small tapered side wings, but the common wisdom is that they can make the panels honk with echoes if done wrong, so I'll pad them well. I have had the drivers for a long time, plus lots of caps and inductors from the '70s and '80, and even the audio millivolt meter and sig gen I made from plans in ETI or Elektor. Never throw anything away, I say!