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PostPosted: Fri Jun 28, 2013 11:19 am 
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greenstiles wrote:
it looks very simple, what are all those big tall things at the back ?


<chuckle> :D


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PostPosted: Fri Jun 28, 2013 11:56 am 
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Come on, we all know about stuff others don't :wink: i used to get engineers and such like come in the shop who couldn't even ajust their gears......


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PostPosted: Fri Jun 28, 2013 11:59 am 
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i wanted to ask you a question please...........i see some interconnect makers, double up their cables.............should you just have a separate centre core for each pos and neg, or would it be ok to use 2 separate centres for the pos and 2 separate outer braids for the neg ? what would the electrical diffs be please.........i'm happy to learn !


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PostPosted: Fri Jun 28, 2013 12:56 pm 
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Sorry, I thought you were joking :)

I'll annotate a pic and post it up.

Re cables. Doubling up would halve the resistance, but as it's minimal (couple of milliohms) anyway, its not a factor. However, it would double the capacitance, which in a cable such as that weird varnished stuff, would make it even nastier. In an RF cable such as this, it would probably not make much difference as capacitance is very low anyway. Twice nothing is still nothing (in audio frequency terms). The series inductance would be approximately halved, which again wont have much impact. In the real world, these three phenomena will interact leading to what could be a fairly complex reactance, but again that will probably only be significant at RF, not AF.

In short, doubling up shouldn't make any difference at all.

Here's your pic

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PostPosted: Fri Jun 28, 2013 1:11 pm 
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Cheers for that, Does doubling up the size of speaker cables affect the sound ?.............what opamps have you used ?.......do you know anything about opa627's ?......been reading they are good quality ?


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PostPosted: Fri Jun 28, 2013 3:22 pm 
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Unless the cable is not sufficiently rated in the first place, doubling up won't change anything.

Op-amps. Why you wanna know? The ones I've used are excellently specced and correct for the application. They are used within their operating parameters. If you change for a different type, there will be no difference. If I was using them outside of their parameters, or they were rubbish, changing them might make a difference - it might as easily make things worse as better. However, they are not on the list of currently fashionable and expensive op-amps as listed by that pool of 'geniuses' known as 'DIY Audio', so if I was to build a production version using professionally made PCBs (and I probably will, I'm MORE than happy with performance) then market demands (ie people who think they know much more than they really do - 'audiophiles' -"spit...") that I use a fashionable op-amp, so the cost will rise to cover the cost of the pointlessly expensive parts. :)

OPA627 - looks OK. Input noise voltage not spectacular. Far too expensive for the performance (in an audio application anyway) http://www.ti.com/lit/ds/symlink/opa627.pdf

Here's a block diagram of the amp to give you a better idea of what's in there. Not sure why the vol pot disappeared when I uploaded it to photobucket... If you want to build a simpler version and experience the satisfaction of building yourself a really respectable little headphone amp quite cheaply, I can sketch out a diagram and put together a kit of bits for you.

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PostPosted: Fri Jun 28, 2013 3:47 pm 
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ah you see, that diagram i can follow quite well cheers..........

i was just curious as i have read lots of people use these, but i understand what you said before, about they have no 'sound' but the sound my be affected if they are used in-efficiently. Same with the silly cables, if they do affect the sound at all it will be because of things not working as well as they could.


Better equipment yes ......cable is basically a cable.

Thanks for the offer of a kit, but i think i'd prefer to build a turntable chasis or speakers, than an amplifier, i'd prob do something wrong. :oops:


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PostPosted: Mon Jul 01, 2013 7:18 pm 
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i got round to securing my clock recently, i put a gromit round it and made it steady...........it seems my music is a bit more focused and flows a bit better .....or it could be my imagination.


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PostPosted: Mon Jul 01, 2013 11:34 pm 
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Not necessarily.

I believe the master clock of a CD player is vitally important as it is accepted that clock jitter in a digital system is extremely detrimental. Jitter is very difficult to measure. I can't do it at home, and can only get an idea with the kit in work (it's not designed to do it) but when I was doing the CD67, I did note a reduction in jitter when I rejigged the clock. I bonded the crystal to the board, grounded the can, fitted a grommet over the can, and moved the components closer to the crystal so all the interconnecting tracks where shortened. It was hard to quantify the difference as my view of the jitter was a visual blurring of the edges of the clock waveform which came into better focus after the mods (told you the test kit wasn't ideal!) but the subjective change was very similar to yours. I also noticed what could be described as better focus, and more solidity to imagery.


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PostPosted: Wed Jul 03, 2013 8:43 pm 
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Headphones worthy of my new headphone amp :)

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