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Post by karatestu on Feb 17, 2022 20:38:44 GMT
Yes, I like the look of the tallest pipe stand you've shown. Your trouble is that you've got a hyperactive mind that is more like a buzz saw than anything else. I can't actually imagine you settling down with anything! Ha ha. Richard Dunn said I was like a dog with my head out the car window and if I didn't stop looking at everything I would never get anything finished. Look what happened - five years later and I still haven't finished a pair of speakers  Just one or two little things to iron out now. Honest  |
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Post by karatestu on Feb 18, 2022 8:37:17 GMT
Tandberg used to make a not vastly dissimilar speaker to that? Is this them Jerry / Martin ?  |
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Post by karatestu on Feb 18, 2022 8:41:10 GMT
Or these ? Stands aren't cylindrical though.  |
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Post by jandl100 on Feb 18, 2022 8:44:24 GMT
Hmm, no, huge polygon things maybe getting on for a metre across.
I can't find a pic atm but I visited someone who had them in his (very large) kitchen. He'd just collected them thinking they were about 12 inches across and didn't quite know where to put them!
I thought they were Tandberg, maybe not. Quite like those Tandberg Fassets in the previous post but much bigger.
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Post by MartinT on Feb 18, 2022 8:53:00 GMT
I can't find them either.
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Post by MartinT on Feb 18, 2022 8:54:23 GMT
Grundig!  |
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Post by karatestu on Feb 18, 2022 9:02:01 GMT
Someone stole them for the set of Star Wars |
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Post by John on Feb 18, 2022 10:10:49 GMT
I was thinking you make a good prop designer for Dr Who
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Post by karatestu on Feb 18, 2022 16:34:12 GMT
Done some more work on the sputnik today. The gaffa tape holding my tweeters in their little plastic spheres was a bodge and only temporary so I could see if isolating the tweeters had any merit. Even with that far from ideal bodge it was clear from the first ten seconds that it was a winner. Since then the tape started to come unstuck and I got fed up pushing it back on. So the next stage was considered and implemented. This is still not the final thing but gives me an idea on how suitable butyl rubber will be to attach the tweeter to the enclosure. I cut out a donut of wheelbarrow inner tube just wide enough to overlap the enclosure and with a hole in the centre that just fits around the edge of the surround.  I then proceeded to add some 3mm thick plastic to the tweeter to make it circular and give a bigger area to stick the butyl rubber to. None of this is seen as the butyl rubber ring very conveniently covers everything right up to the tweeter's surround.  So now the parts were made I had to adhere the rubber ring to the enlarged face plate and the spherical enclosure. This went rather well and looks much better than the gaffa tape effort.  Well it not only looks better but sounds better too. The gaffa tape was a poor solution but this butyl rubber ring has well and truly done the business. These are the best performing speakers I have heard (not that I have heard loads). I just need to think now of how to blend the edge of the butyly rubber smoothly into the sphere without any edges and the re radiation that brings. |
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Post by karatestu on Feb 18, 2022 20:02:37 GMT
One thing that sticks out for me (OK more than one) since I started with isolating speakers from the floor and even drivers from their enclosures is the massive increase in dynamics. It's not subtle. On well recorded jazz there can be brass and woodwind instruments truly soaring. It is truly amazing. The other things being the added detail from less bass mush and the increased sense of hearing the venue or room it was recorded in.
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Post by MartinT on Feb 18, 2022 21:12:09 GMT
Agree completely about the dynamics of real music coming through when it's all working well.
As a drummer yourself, how would you rate the reproduction of drums on these speakers?
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Post by karatestu on Feb 19, 2022 8:36:38 GMT
Agree completely about the dynamics of real music coming through when it's all working well. As a drummer yourself, how would you rate the reproduction of drums on these speakers? Hi Martin. I find the reproduction of drums to be quite amazing. These have only a 6.5" mid bass and 2" tweeter but the dynamics on well recorded jazz is quite something. Same with piano and those are the two hardest instruments to reproduce. There may be better speakers in this regard but I bet they are a lot bigger than mine with a price tag to match. The level of expression of detail in cymbal work, cross stick and brush work is spine tingling. Never heard anything like it (except a real life talented drummer un amplified of course). The drivers are nothing special price wise. The B&W mid bass driver is very well made with cast aluminum basket and smallish magnet which really get out of the way of the back wave. I think this is very important- it's very important to chamfer cut out's especially with very thick baffles. As my enclosures are only 3mm thick they are completely out of the way and the space for the backwave could not be any more open. You can hear the reflections back through the cone if the rear of the driver is restricted. I added blutack and bitumen flashing tape to the the back of the driver in all the right places. I don't know what difference that made if any as I did the brass bar and sand modification at the same time. Interestingly I can't detect much vibration of the mounting flange. The SB acoustics 2" full ranger (can't really call it a FR as it rolls off at 140 Hz if run wide open) is very well regarded on diyaudio, It too has a small neo magnet and very open backside. The way I have it mounted with mounting flange inside the cut out means there is nothing to restrict and reflect the backwave. This little 2" has really good treble dispersion due to the large dustcap which is very much like a dome tweeter with the cone being a small waveguide. The isolation I have implemented at speaker and driver level along with the very stiff 3mm steel sphere and the attention to low re radiation from sleek enclosure shape has paid off massively. They are good drivers but not major expensive and I feel I have wrung the very last drop of performance from them. Happy days, I feel like the last five years of hands on learning has not been for nothing. |
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Post by karatestu on Feb 19, 2022 15:47:56 GMT
I have heard of sand filled baffles (Wharfedale) and plenty of diyers have built a box within a box with the cavity filled with sand but I have never heard of anybody but me filling the bottom third of their speaker with sand. It does several things for me 1) makes the internal volume correct for the bass response I like with that driver 2) soaks up the driver vibration via the brass bar glued to the back of the magnet 3) helps stabilise the brass bar and foot 4) makes the internal shape not spherical so one resonance doesn't dominate 5) damps some of the enclosure wall.
It may have other benefits as well that I haven't thought of yet. These speakers have no stuffing at all apart from the sand and two thirds of the enclosure have no damping on the walls. I don't feel the need to put any of that in maybe due to the very low enclosure wall vibration since isolating the drivers.
The tweeter sphere however does have some stuffing but the internal dimension (144mm) gives an internal resonance frequency way below the pass band of the tweeter. It is crossed over at 7 KHz with a single passive line level high pass which entailed just changing the value of the dc blocking coupling cap in the power amp's input stage. I find this way of filtering for the tweeter is vastly superior to doing it passively at speaker level and it meant one less capacitor in the signal path. I don't need any padding resistor either so there is nothing but wire between my four monoblocs and four drivers
Keeping it simple kicks ass (for me).
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Post by speedysteve on Feb 19, 2022 17:19:04 GMT
I used sandbags packed in the back box / rear driver chamber of my mid bass horns, to tune the volume.
Adds mass and reduced volume.
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Post by karatestu on Feb 20, 2022 8:28:25 GMT
Maybe I should put the sand in bags ? That way I won't get a voice coil gap full of sand if anybody accidently puts them on their side. Saying that, if I also fill the stand with sand then these things won't be toppled easily at all.
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Post by karatestu on Feb 21, 2022 4:46:42 GMT
Anybody know of a good way to finish a sphere ?
Veneer and leather are obviously a no no. I can only think of spray products. How about powder coating the steel parts ? I could use a steel sphere for the tweeter as well.
Single colour or two tone ?
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Post by MartinT on Feb 21, 2022 6:16:26 GMT
Powder coating a demur colour would probably look best. A shade different tone for the tweeter sphere?
Or Hammerite for a funky look?
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Post by petea on Feb 21, 2022 7:57:50 GMT
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Post by karatestu on Feb 21, 2022 9:03:04 GMT
That two tone crackleure looks really interesting. Thanks for posting that Pete. Martin's suggestion of hammerite may also be good especially if hammered finish. Satin may also be good. My B&W kevlar mid bass have a bloody yellow cone. I wonder if I can colour it in with a black permanent marker ? Without adding any more weight of course and not affecting the T&S parameters. |
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Post by speedysteve on Feb 21, 2022 9:04:47 GMT
Can you heat the thing up like powdercoat requires? Plastic fitting etc will melt
As good a finish is achievable with primer, filler, filler primer, top spray.
I hate powdercoat on anything steel / aluminium that will be left outside. Why do they insist on using it, must be cost.. useless stuff.
Black permanent marker like Shapie etc usually comes blue'ish.
Might be some that better.
A light dusting of spray paint😱
Brush on paint would be too heavy I would think.
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