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Old 2nd February 2011, 03:36 PM   #3971
AndrewT is offline AndrewT  Scotland
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Sepo,
do you have a thread in the tube/valve section?
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Old 2nd February 2011, 03:37 PM   #3972
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Sepo,
do you have a thread in the tube/valve section?
Guess I should start one, huh?
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Old 2nd February 2011, 03:40 PM   #3973
AndrewT is offline AndrewT  Scotland
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Judging by your earlier response, I think you will have an audience for what you have done.
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Old 2nd February 2011, 05:46 PM   #3974
udailey is offline udailey  United States
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Andrew/David
I think you can do it if you set the LDR at, for instance, 50k and leave it there. I dont mean that you would ever change the value after you set it. I am sure .01 is not possible. Certainly I think its possible to get 1%. .1% probably not. They will drift but if you do preliminary matching at about 50k then you should be able to get them to drift alike. So if one goes to 52k I would expect the other to also go to 52k. Sticking them near tubes or anything with a large voltage drop wouldnt help things, I admit, but I think its worth trying. Its as simple as a bit of regulation and a few caps followed by another trimmer to get you down to 50k. Whole additional circuit would cost less than the resistors considered for use right now.
I wont keep chasing after you about it, I just think that if you need a resistor for series that is not going to change value... that its possible down at 50k and perhaps a bit higher. If you want to vary them then I dont think it is. I suppose if .1% is the max then this is not going to work well. 1% I think its worth trying.
Stuart, the piece you sent me a few months back is working great as I type. Would like to try those other options you mentioned if you could pm me some part numbers.
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Old 2nd February 2011, 08:45 PM   #3975
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Well, the last one was so good I couldnt help myself. Is that what they call 'chasing the white rabbit?'
Uriah

What has Kingwa sent you this time - and what's it like ?

Andrew
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Old 3rd February 2011, 03:12 AM   #3976
udailey is offline udailey  United States
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Hi Andrew
REF7. I had to know if it could be better than REF5. Its got better depth. Things sound a little more real. However there was already great depth and realism. Gushing about it is not what I am about to do yet. The REF5 was incredible and this seems on par and a tiny bit better but I have done no side by sides yet.
Its massive. At least 2.5 times the size of the REF5. Ridiculously large but packed with power supplies.
Would I buy the REF7 again over the REF5. Probably not. The REF5 is as good in most cases if my ear's memory serves me correctly. I will have to do side by side but maybe thats over the weekend.
Uriah
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Old 8th February 2011, 01:38 PM   #3977
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I finally managed to make one lightspeed attenuator. After testing it seems ok.
I have now - in testing configuration bypassed the TKD pot in my somewhat modified Audio Note preamp.

It sounds very good...

Vel it looks like a mess but sounds good...

I am using a 50k pot for volume but it is exstremely sensitive. I think I have to use a 100k pot or maybe 250k? Is that smart?

Click the image to open in full size.
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Last edited by bambadoo; 8th February 2011 at 01:47 PM.
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Old 8th February 2011, 05:55 PM   #3978
udailey is offline udailey  United States
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Sometimes, when they are so sensitive you may consider finding a way to keep the shunt LDRs at a lower max resistance or a way to keep series at a higher min resistance. This way you do not get incredibly loud volume on accident with touchy LDRs. It may be your pot and it may be the taper of your pot as well. Since all LDRs have a different resistance taper to them you may have a pair that increase in resistance faster than most in shunt or the opposite in series.
Anyway.
Here is the things to try
100k pot dual gang log. This will help for sure.
10k-30k resistors in place of the 100R resistors that are feeding your Series LDRs. You will NOT get max volume this way and your resistance curve will change a lot, but it will help with your immediate problem.
5k-20k resistors in parallel with the resistor side of your Shunt LDRs. This will keep shunt from increasing in value to fast and will also have negative side effects as mentioned above with series fix.

Probably your only problem is that you are not using 100k dual log pot. However if you have high gain amp and you have super efficient speakers sometimes the normal LS setup can be tuned to work better with that sort of system in these ways. There are other options like different voltage to drive them or series 10R pot before 100k pot.
Try 100k first and let us know.
Uriah
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Old 8th February 2011, 05:59 PM   #3979
ua100k is offline ua100k  United States
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Quote:
Originally Posted by bambadoo View Post

I am using a 50k pot for volume but it is exstremely sensitive. I think I have to use a 100k pot or maybe 250k? Is that smart?

Click the image to open in full size.
You should try the Warpspeed solution. It has much better control and operates the LDRS within the current tolerance of the LDR. It goes from Dead silence to full volume. Less current draw as well.
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Old 8th February 2011, 08:49 PM   #3980
udailey is offline udailey  United States
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All LDRs that are operating in any circuit are operating within the current tolerance of the LDR. Any that arent.. dont for long.
Dead silence is achieved by pumping up the resistance of the series LDRs to extremes which emulates very high resistance pots. The higher the resistance the higher the Johnson noise and the higher the resistance the more roll off you get of high frequencies.
Its a solution. Just as imperfect as others.
The best solution for low volume with LDRs is to parallel shunts to achieve low to zero volume with lower series resistances that allow a better sound. I suppose that sound is better in my opinion.
Uriah
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