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Post by ant on May 7, 2017 9:54:13 GMT
There is a shure m97xe in it at the moment, have allsorts of other bits and bobs to try in it
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Post by ant on May 6, 2017 20:18:32 GMT
Finished that unipivot I was playing with URL=http://s1378.photobucket.com/user/floydiepink/media/DSC_0499_zpsqxxodjo2.jpg.html] [/URL] Very good for a lash up This is the mk2, the original had some issues that the mk2 adresses. There will be one or two changes to this before its completely done. Its currently belting out some bowie
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Post by ant on Apr 18, 2017 18:52:44 GMT
What about one of these? :-) A project im working on
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Post by ant on Apr 6, 2017 16:17:33 GMT
Didnt think of that :-) ive taken it to bits now too.... The top shelf will get veneered, the thicker one of the two laminated ones, then made into a levelling platform for the turntable.
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Post by ant on Apr 6, 2017 13:18:20 GMT
Tried it with big pillows.....
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Post by ant on Apr 6, 2017 12:55:50 GMT
It wasnt the rack itsself, it was the effect its position in the room had on the acoustics of the room. The corner it was in has always caused a slight honk, the stuff that was in there before broke up the mode, but the rack didnt, it exacerbated the problem.
Putting it back as it was is better
The room is fairly benign, but it doesnt take much to alter the balance
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Post by ant on Apr 5, 2017 19:27:44 GMT
Took the rack out as it was causing havoc with the room modes where it had to be positioned. Shame, i'll take it to bits and use the laminated top and base for something else
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Post by ant on Apr 3, 2017 11:37:45 GMT
What im using at the moment The other 5 are in various states of repair
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Post by ant on Mar 30, 2017 8:46:33 GMT
Further to this, the really interesting motors are the ones that are both turbo'd and supercharged. Both turbos and superchargers work on the same principle, i.e an impeller or air screw that is spun by the engine, that forces air into the engine. The difference is that the supercharger is driven by the crank and the turbo is driven by the exhaust gasses.
Historically turbos lagged. The reason being that at low revs the exhaust gasses were not travelling fast enough to build up boost pressure. The amount of fuel in the mix was more than the optimum for the mixture, so until the turbo spooled up the mixture was rich causing the hesitation.
A supercharger doesnt have this issue as it is driven by the crank via a gear set so for any given revs the air charge is a known quantity.you know exactly how fast it is spinning and how much boost it will produce, so air fuel ratio can be optimised, so no lag. The turbo however is more efficient at meduim to high revs hence will produce more power. That massive shove in the back when a cosworth yb comes on boost is unbelieveably grin inducing. By combining the 2 systems you can have the charger produce clean low to medium power and the blower take over at higher revs. the charger fills in the gaps as the blower spools up, producing a very efficient and clean engine with very linear power delivery.
In terms of reliability, the main issue I can see isnt mechanical, its the electronics. Managing the fuel system requires accurare monitoring of the systems it constantly adjust the mix. Efficient fuel air management is the key to any clean engine, and the electronics required are expensive and complicated. Its a clever system that can be optimised electronically to either be very very efficient and clean burning, or powerful.
However sometimes I still think theres no substitute for cubes. A 2.0l turbo may produce the same power as a 4.0 v8, but they are a completely different animal.
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Post by ant on Mar 29, 2017 15:48:34 GMT
With the modern small cc turbo'd engines the inherent reliability problems are the same as any other turbo'd car. I.e worn actuator diaphragms cracking and causing boost pressure losses, and shaft bearings in the turbo itsself wearing, letting oil into the fuel system. Due to the very high rpm of the turbo and the heat generated, the bearings take a huge amount of stress, and the oil feed itsself to the turbo is at a relatively high pressure in order to lubricate it properly. Once the shaft seals go, high pressure oil ends up atomised in the air the turbo pulls in and is burned along with the air/ fuel mix. This is why you see so many smoky older diesel cars, its not diesel smoke, its the oil in the combustion chamber.
A turbodiesel had a high compression ratio to ignite the fuel/air charge in the combustion chamber, and the block, rods and crank are beefed up compared to a petrol motor to cope with this, so arent under as much stress generally as a turbo'd petrol car. They usually just end up rattly and smoky
Petrol turbos have a much lower compression ratio compared to diesels as the plugs ignite the fuel air mix, and compared to a non turbo petrol engine, the compression ratio is lower again for the turbo'd ones due to bigger bangs from the charge in the cylinder. Same shaft seal problems are possible, but the other issue 'hypothetically' is that if the shaft seals go and it starts burning oil, if left, the coking up of the heads and piston crown can gradually make the compression ratio higher. I.e, the chamber area becomes smaller, but the same charge is forced in. The rods and crank may not be hefty enough and result in a blown engine.
In practice, this is probably a none issue, but normal wear and tear on the rings, bores, rods, crank, valves and guides ect may be accelerated by the bigger bangs in the combustion chamber.
Ive worked on loads of old Ford cvh turbos, and one or two cosworth yb engines. I once worked on one that was built up from a standard 1600 cvh. The guy had not changed the head for the turbo head and the compression was far too high. Standard crank rods and pistons were ejected through the sump..... We built him another using the right head, and rods from an 1800 diesel, a slightly uprated actuator and that one was fine.
Compared to an older small cc non turbo car, the new ones motors are probably more highly strung, but compared to any other turbo'd car all things are probably equal. Turbo cars if looked after are no less reliable than non turbo, but if they go, they go spectacularly. But with modern fuel injection systems the engines are much more efficient and cleaner due to a much better burn in the chamber. This is why the 1 litre turbo ford ecoboost in the fiesta makes more power than the old 1600 cvh turbo with the garrett t2 blower in the top end fiesta rs turbo from back in the day
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Post by ant on Mar 28, 2017 11:06:12 GMT
These dont require a crossover other than the cap on the tweeter as the main driver is run full range, and no doping of the driver either, again no need
Edit: steve is my dad hence knowing. I had abit of input into these, not in the design mind you, just in the techniques needed to build and veneer them as he hadnt tackled veneering before, and getting the router to do what we wanted it to, again having not used one before, hes a hand tools guy
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Post by ant on Mar 24, 2017 18:53:04 GMT
Last thing was my ortofon mc10 red body and matching mca 10 head amp. Just to raise abit of cash so i could buy a very very scruffy jvc ql-y5f that I wanted to restore. Havent got round to that yet due to commissioned builds of other stuff. I did manage to get an original jvc headshell for it, and ended up having to buy an sl1200 counterweight to replace the missing original. Ive also resprayed the aluminium platter satin black as there was huge amounts of corrosion rhat was impossible to polish out. The corrosion in the edges was too deep. It works perfectly, but looks terrible. I tend to keep old stuff around until I need some capital for some project or other then sell off a couple of bits to fund it
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Post by ant on Mar 19, 2017 14:32:35 GMT
I listen pretty much exclusively to vinyl. I have cd and computer audio via a mac mini. I havent used the mac in months, and the cd player sparingly.
I dont really have the time to listen to the system as it is, but i dont really care much about the digital portion of it.
With the mac I find myself skipping songs, playing something half way through then going to something else. With cd kinda the same. I could quite happily do without either and not really be bothered.
I have to be in the mood to sit down and listen which isnt that often these days with the kids and constant demands on my time (sure we have all been there) the deck is what I use when i do have the time. And people leave me alone when the deck is spinning. Digital just doesnt do it for me and quite frankly i dont know why. Its much easier, probably sounds better and I have much more choice of music with it.
But then everyone is different. And that is good
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Post by ant on Mar 16, 2017 12:41:30 GMT
Mclaren putting the feelers out to Mercedes re engines according to BBC news.
Doesnt bode well
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Post by ant on Mar 15, 2017 13:13:50 GMT
Level 42 eyes waterfalling, persuit of accidents and are you hearing from the persuit of accidents album.
Actually the whole first and second level 42 albums are pretty dynamic
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tonearms
Mar 15, 2017 9:44:49 GMT
via mobile
Post by ant on Mar 15, 2017 9:44:49 GMT
Ive never had an expensive arm on a Tt. First had a linn basik and linn akito on the lp12. Both shite. Then put a project 9 carbon fibre arm on the lp12 which was much better than either linn.
Had a mayware formula 4 and a sonus formula 4 that were fantastic on a td150, the jbe series3 and a denon dp2550. Loved them on everything I put them on.
Had a helius standard that was very good when rewired, and an sme 3009 that was abit meh.
I build a load of unipivot arms ranging from a very high mass one from oak that was built to work with a dl103 rhat was stunning with that, but useless for anything else, to an aluminium and carbon fibre one that was very good indeed.
Careful attention was paid to resonances in the arm tube, the wand ended up like Swiss cheese after drilling it out in various places until it was nice and dead.
I found that it wasnt so much the frequency, but the decay of the ringing that made the difference. All arms wands will ring, how quickly they stop ringing depends on how clean they sound. Its a case of the tail wagging the dog, the cart will dump energy into the arm and the arm needs to be able to get rid of it as quickly as possible in my opinion. A u/p wand has one point that energy can get out through (the pivot point) which seems to lend itsself well to this.
The best sounding one i made used a flat tapered perspex wand rather than a tube. Very few mid to high frequency modes in it and fast energy transfer.
Only 'high end' arm ive heard was the linn ekos, an early one, I had it for about a week.
I currently use a modified rb251, thar has had the arm tube drilled and had foam damping put in, rewired with silver and had an aluminium rod bashed into the counterweight stub to damp it. It has a separate earth and detachable arm cable made from Banbridge 4 core mic cable. Much better than the stock rb, i have a standard rb250 for testing stuff with and comparing them is like chalk and cheese.
In terms of design, i think that higher quality machining, bearings ect are all very well and make a better product, but more attention needs to be paid to the energy being dumped into them arm by the deck and cart. Folk are sniffy about the use of plastics for example, but engineering plastics ( nylon, delrin et al) have some desirable qualities if used in the right manner. But the tactile quality is not the same as machined alloy.
Personally i prefer unipivots from a design standpoint as I think they lend themselves well to fast energy transfer and simplicity. Less parts mean less vibrational modes from these parts colliding at the bearing(s) and having to be gotten rid of, and less bearings, 1 instead of 3 means one path out of the arm rather than 3
think of it this way A cart converts kinetic energy into electrical energy. But it doesnt convert all the kinetik energy into electrical energy, so the remainder has to go somewhere. Energy cant be destroyed, only changed. The remaining kinetic energy that isnt converted int electrical energy by the generator in the cart, or heat by the cart suspension eemains as kinetic energy and is transferred into the surrounding structure. This will feed back into the generator and be converted into electrical energy after a delay while it bounces around in the arm structure, by which time, more energy has done the same thing, creating a kind of delayed ghost signal. You and I cant hear it as it is so low level, but its there unless it goes elsewhere via the structure, and manifests itsself as a barely perceptible distortion. If this can be kept away from the cart and transferred elswhere, i.e out of the arm, then it could mean better sound. My thoughts on this may be meaningless, just what I have formulated over the years of buggering around with arms
Cheers ant
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Post by ant on Mar 7, 2017 10:48:04 GMT
2 this week, tinker tailor soldier spy John le carre and hms ulysses which is Alastair mcleans first
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Post by ant on Mar 3, 2017 22:12:46 GMT
No probs Chris, thanks for checking for me
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Post by ant on Mar 3, 2017 19:05:22 GMT
Thanks chris
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Post by ant on Mar 3, 2017 18:24:10 GMT
Hi guys, i need a counterweight to fit on a jvc ql-y5f turntable that im going to be restoring shortly. The counterweight is missing and it was missing the original headshell. Ive managed to source an orifinal jvc headshell but the counterweight has so far proved impossible to find. I havent seen one at all, not even one for silly money. Id love to get it back to stock, but if I cant find one its tough.
The stub on the arm is 14mm diameter, and it appears that a technics sl1200 one will fit, but before i buy one i thought id ask here if anyone has something off a jvc or something that will fit and look more like the stock silver one it had originally.
Cheers ant
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