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Old 13th February 2013, 03:43 PM   #4981
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Quote:
Originally Posted by Nanook View Post
Taking swipes at those folks that provide insight into their designs is one of the greatest things about DIYaudio. Personal attacks are why many creative folks simply give up on certain discussion boards.

I don't know Uriah Dailey or George but can tell you this: pitting folks against others is a pretty lame thing to do. Both Uriah and George have provided so much helpful information with no direct commercial gain, one ought to be ashamed of one's behaviour if trying to pitch a fight. How many ways to skin a cat? Too many. And I doubt that either is getting rich selling the LDRs , etc. They choose to provide information voluntarily. So for any and all that seem intent on continuing such nonsense, please stop. You were probably raised better than your actions here might indicate.
Very well said!
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Old 13th February 2013, 09:47 PM   #4982
tinitus is offline tinitus  Europe
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post removed

sorry, rules suggest not to waste time on debating moderation

this thread is exclusive for Lightspeed design
it is free for everyone to build
and it is free to debate anything related to Lightspeed

for obvious reason we have to keep threads on topic as much as possible
and it is free for all members to open other threads, and build whatever they like

from now on all non tech off topic posts will be removed
end of story
thats all, thanks


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Old 16th February 2013, 08:45 AM   #4983
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Thank god sanity has prevailed.

Cheers George
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Old 3rd March 2013, 09:28 AM   #4984
stajo is offline stajo  Sweden
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Hi

I overtook some old project from a friend. I dont know what GB it came from, not how it was matched (or not) and in fact I knew little about the cards so I started to investigate them.
Click the image to open in full size.
My plan is to investigate if I can use them for an 8 channel DCB1 build. As you can see on the pics one card has bridged pot-holes, and the other varies. The left two has red 2 k variable multi turn resistors, and the one to the far right has 1 k singleturn variable resistors.

I hooked it up on a 5 V supply with a dual 100k pot for starters, and then I hooked up a signal generator and my scope on the in and outputs.
Click the image to open in full size.


I putted the 2 k variable resistors somewhere half ways and also the 1 k (on 0,5 k) and started sending in 1 V squarewave 1 kHz. It seemed like the outputs has signal to the left and gnd to the right, looking at it from the top. But the channels also seems mirrored so one has input to the left and output to the right and the other one vice versa.

My measures says that the two card with the red variable resistors put to 1 k "works", ie they give an increasing signal when I turn the main 100 k pot. The bridged card and the one with blue pots seems so give very low and not increasing values.

Click the image to open in full size.

So, some first questions to give me a push on my investigations:
Anyone knows what GB it came from and if there are documentation somewhere?
What suggestions do you have regarding main pot and card mounted pots? Shall I keep the 2 k pots on the boards and try find similar? Shall I decrease value on main pot?

That will be enough for starters

Best regards
Staffan
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Old 3rd March 2013, 11:16 AM   #4985
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Just after a quick look at your pics, my first advise to you is to ditch the pot you are using, as it will not last long with current it is going to have to handle. Try to get hold of a 5watt dual wire wound one that are around.

Cheers George
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Old 3rd March 2013, 11:25 AM   #4986
stajo is offline stajo  Sweden
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Thanks George. Shall I stick to dual 100 k? Any wattage to talk about over the board mounted ones? I have some 1 k laying around, I think I read somewhere that its the recommended setup? Unfortunately the once I have is with solder pins in straight line, boards are made for pins with offset on the middle one. I guess theyre 0,25 W or so.

best regards
Staffan

Last edited by stajo; 3rd March 2013 at 11:28 AM.
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Old 3rd March 2013, 05:09 PM   #4987
stajo is offline stajo  Sweden
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PS. I know found out that the cards are from a GB from a swedish forum, made by a former forum member. But its original spec is from this thread.
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Old 4th March 2013, 02:01 AM   #4988
udailey is offline udailey  United States
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1k .25w is fine but you must use a several watt pot for 100k as long as its running all those boards. See AndrewT's comments a few years back on pot ratings. Assuming 5v at 20mA per ldr is not going to result in a long life for your pot. Maybe a wirewound pot of 3-5w would be a good selection.
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Old 5th March 2013, 09:50 PM   #4989
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Hi George,

I'm close to embarking on the lightspeed journey, just wanted to run couple things by you....i run a Cambridge Audio 640c v2 CD player using wolfson 8740 dac chips direct out via 3.3uf cap,That sounds modded to me I have no idea what the output impedance will be, it needs to be 200ohms or lower

my amp is a sugden solid state which is an integrated but I intend to 'tap in' to the power amp section when using the LSA by-passing the preamp section altogether, not sure what input impedance is but it uses a 50k alps pot as standard if that is any indication??.This 50kohm indicateds that the input impedance to the amp must be higher which is good for the Lightspeed Any observations would be greatly appreciated. Finally I have slight hearing loss in my left ear and wonder would the balance control effect of the trim pot be best way to achieve balance control or better to use 2 pots??Yes the calibration pot can be used to shift the image left or right. Cheers George

Many thanks

Terry Maddocks

Thanks for your response George, appreciated, gonna have to do this I think
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Old 7th March 2013, 07:45 PM   #4990
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Hi all,

I've just completed my second attempt at building a lightspeed thanks to 4 LDR's that arrived the other day courtesy of Uriah.

It plays at low volume, sounding quite thin, but neither the volume pot or the trimmer pots are having any effect unfortunately. I followed this diagram - just wondering, is the wiring for the pots correct?

Click the image to open in full size.

Click the image to open in full size.

apologies for the crap picture

Any advice appreciated. Thanks.

P

Last edited by kristeva; 7th March 2013 at 07:48 PM.
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