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Old 11th March 2010, 04:14 PM   #3071
udailey is offline udailey  United States
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I am testing LDRs today actually. 480 of them fired up and have been burning in for 72 hours now. Tested 3 different positions so far and will continue to test either 1 or two more positions. Never have tested 5 positions before but my new test fixture is making things way easier, so we will see.
Um, lessee here.. last time I didnt offer balanced. I have before but the last batch didnt produce many balanced sets. I have to wait til I am done with this batch to know how things went. Probably be done with all the testing today or in morning and then I have to work with the spreadsheet for a few days. Give me til middle of next week and shoot me an email about balanced if thats what you are after.
Uriah
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Old 12th March 2010, 07:12 AM   #3072
fbee is offline fbee  Germany
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Iīm pleased of the concept as Iīm looking for a passive volume control between my Linn Akurate DS (out 2Vrms, 300Ohms) and my Linkwitz active crossover (in max 0,7V, 10kOhms, www.linkwitzlab.com/orion_asp.htm).
Presently, I do fixed attenuation with a classic voltage divider.

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In Lightspeed system , which of the R is changed by LDR? R1 , R2, both?

1) Would your Lightspeed work fine with my system ( 300Ohms Out 10kOhms in) or are there any impairments to be considered?
2) In the future I might want to add remote control via LAN or RS232(out of thr Linn). How would this work with the LDR system?
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Old 12th March 2010, 01:35 PM   #3073
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Default It's LDR volume-control 'nirvana'?

Correct me if I'm wrong here... But, although I understand how LDR eliminates (rotary) switch contacts (which is a agood thing), it does not solve the impedance mismatch and energy dissipation issues associated with adding (variable) resistors to the signal path.

I suppose that in an 'ideal' system, LDR could be as close to 'nirvana' as you could get, ideal being: low impedance, high volatge source (CD player); high impedance sink/amp; and short (low capacitance) cable runs (albeit not balanced)... Which probably represents a reasonably large number of systems out there, but certainly not all.
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Old 13th March 2010, 02:12 AM   #3074
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Quote:
Originally Posted by fbee View Post
1) Would your Lightspeed work fine with my system ( 300Ohms Out 10kOhms in) or are there any impairments to be considered?
2) In the future I might want to add remote control via LAN or RS232(out of thr Linn). How would this work with the LDR system?
Hi fbee, your xover has probably a fet input opamp at the input stage, if so you can then replace the 10k to ground resistor at the input of the xover to 100k, then all will be fine.
Cheers George
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Old 14th March 2010, 06:32 AM   #3075
fbee is offline fbee  Germany
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George, I tried to send you an e-mail, but it was rejected by your server.
Could you please PM me another adress? Thanks Frank
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Old 14th March 2010, 09:39 AM   #3076
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Quote:
Originally Posted by fbee View Post
George, I tried to send you an e-mail, but it was rejected by your server.
Could you please PM me another adress? Thanks Frank
georgehifi @ optusnet.com.au
Remove the spaces. Frank don't send anything over 400K or it will get rejected


Cheers George
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Last edited by georgehifi; 14th March 2010 at 09:41 AM.
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Old 14th March 2010, 10:05 AM   #3077
fbee is offline fbee  Germany
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George, the e-mail (only one a few words for testing) just came back again, saying it was blocked. I shaded your adress here:
SMTP error from remote mail server after RCPT TO:XXXXXX.com.au>:
host extmail.optusnet.com.au XXX <XXX.com.au>... Mail from XXXXX blocked using Trend Micro oRBL+
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Old 16th March 2010, 07:16 AM   #3078
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Default LDR pre

Hi all,

thanks to George and Uriah. I made an LDR pre and connected to Mccormack DNA 225 through pioneer CD player and B & W 801 MkII. Analysis Plus speaker cable with my Diy $3 interconnect. Power supply 3 stage regulation. 18 VDC to 12 VDC to 5 VDC.

Smoked my $2400 tube pre amp ( I do not want to mention the brand) and shook the four walls of the listening room. My friend's wife came out from the kitchen and shouted. The best proof of the real sound preasure and recognition. reduced the volume to get a good dinner and avoid expensive divorce.

Thanks to Uriah and George for all their advise.
A simple circuit of a humle brain. Give a brake to formulas and frequency response. Brain is so complicated that it will never follow formulas while listening music. It simply enjoy music as long as you are able to listen.

Once again thanks to George and uriah.
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Old 16th March 2010, 10:02 AM   #3079
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Quote:
Originally Posted by fbee View Post
George, the e-mail (only one a few words for testing) just came back again, saying it was blocked. I shaded your adress here:
SMTP error from remote mail server after RCPT TO:XXXXXX.com.au>:
host extmail.optusnet.com.au XXX <XXX.com.au>... Mail from XXXXX blocked using Trend Micro oRBL+
Your the only one getting blocked Frank, I don't have another email address. Post your questions here and I'll try to answer.
Cheers George
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Old 16th March 2010, 10:36 AM   #3080
fbee is offline fbee  Germany
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Sorry George, for the inconvenience, something seems to be wrong with my e-mail.

However, Iīve not made it yet through all the posts, but even with the search function I couldnīt retrieve information on those two topics:

1.)
In order to harmonize the curves between the right and left channel:
Did you try to replace each LDR element with a "field" of 4 (or,9 or 16) LDRs, two (3 or 4 ) in line, then the two (3 or 4) lines in parallel. The individual LDRs do not need to match, just the resulting R of the "field" needs to match between the channels.
A 10% deviation of one LDR in a 4 / 9 / 16 "field" would result in a "field" deviation of only 2,5% / 1% / 0,6%.
But I wonder, if more elements could also have negative side-effects (THD?)

2.)
Remote Control via RS232 or ethernet:
It would be an option to replace the pot of the Lightspeed with a motorpot and control this motorpot via RS232/ethernet remote modules. OK.(personally I donīt use IR remote in my system)

What do you think of directly dimming the LDRs via a RS232 or ethernet module? Are you aware of anyone who tried this?

Again sorry if I doubled some topics that were already mentioned here

Cheers, Frank
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