It sounds really nice only 1 problem: volume level at lowest level is too high. This sure is a problem. The LS attenuator does not go low enough in level when you use it in a passive preamp connected to a DAC. I have to put it at the lowest level to be comfortable. So I need optocouplers with a higher end resistance.
nicoch46 said:
The input selector has only a dc signal for the input relais.
Like this:
An externally hosted image should be here but it was not working when we last tested it.
nice work
Is it possible that you have series and shunt switched around on your pot? Mine goes down to a whisper. Not muted but a whisper. I have had a few people email me that theirs is to loud from the start and the problem was that they had a dual log pot with series LDR connected where shunt should have been connected on the pot and shunt where series should have been. After correcting this they had quiet when they needed it.
I imagine you probably did it right though. Maybe you need another series LDR on each channel or does your pot not go to 100K?
Uriah
I imagine you probably did it right though. Maybe you need another series LDR on each channel or does your pot not go to 100K?
Uriah
udailey said:
haha
thats ok. But I found a solution. A small trimmer on the volume pot so the series resistance at the lowest position increases from 10k to 100k or higher. Now the level can be turned down low enough. Only the logarithmic function is now way too much. Have to order a linear pot.But I am happy now, it works down to really low levels even when 2V RMS at the input from the DAC.
Poweramps have full output at 1V RMS input.
Modded(for high input levels) level controller:
http://www.grotel.nl/photo/LScontroller2.jpg
with R6 you can set the series OC resistance higher or lower. This will influence your max. att.
It works like a charm
PS another nice side effect: the shunt OC is not at max. current very quickly because of the extended range.
http://www.grotel.nl/photo/LScontroller2.jpg
with R6 you can set the series OC resistance higher or lower. This will influence your max. att.
It works like a charm
PS another nice side effect: the shunt OC is not at max. current very quickly because of the extended range.
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jkeny said:
If I remember, the distortion characteristics of the LDRs are best when there is a relatively small voltage drop across them. When you need higher levels of attenuation you can benefit by putting two in series. There's something to this effect on one of the web sites, can't remember which one, probably the manufacturer.
found it It indeed shows more distortion at very low led supply currents of uA's.
http://www1.silonex.com/audiohm/levelcontrol.html
It indeed shows more distortion at very low led supply currents of uA's.http://www1.silonex.com/audiohm/levelcontrol.html
my mail to Silonex:
Hello, Ordered 50 of these OC's at Farnell and what I've found was not pretty. What I've got from Farnell were oc's from the 109 batch. Over 80% of the 109 batch is going from 1k to 2Mohms when applying 25ma to 8,5 uA. The other 20% was out of spec. also. Only not so much as the 80%. I still had 25 oc's lying about from 2 ears ago and they were stamped:085 but those were within spec and they will do 24 ohms to 12k at te same currents as the 109 were tested with. For a R2 series this 109 batch is too much off spec. and unacceptable to use. Of the 50 only 1 was reasonably within spec. which is a dramatic outcome. I'll send the oc's back to Farnell and not use your oc's anymore until I get oc's that are within spec.
Hello, Ordered 50 of these OC's at Farnell and what I've found was not pretty. What I've got from Farnell were oc's from the 109 batch. Over 80% of the 109 batch is going from 1k to 2Mohms when applying 25ma to 8,5 uA. The other 20% was out of spec. also. Only not so much as the 80%. I still had 25 oc's lying about from 2 ears ago and they were stamped:085 but those were within spec and they will do 24 ohms to 12k at te same currents as the 109 were tested with. For a R2 series this 109 batch is too much off spec. and unacceptable to use. Of the 50 only 1 was reasonably within spec. which is a dramatic outcome. I'll send the oc's back to Farnell and not use your oc's anymore until I get oc's that are within spec.
I would agree that the manufacturing of the Silonex is terrible. Its as if instead of laser cutting the resistors they use a hacksaw. This is why the matching is difficult and frustrating. Also why its nice to have several hundred to match from. More end up matching. In my last batch I had equal parts 408, 109 and some other number. I found many matches in my LDRs and did not find one batch number to produce more matches than another. I did not have 085 I dont think. I wish I had kept track of batch numbers though as that would be interesting and as you have shown us is good information for us to have. It would also be nice if ALLIED would sort into batches for me, unfortunately thats not the case. I spoke with Silonex and to purchase direct I would have to buy 10,000. Thats not going to happen. Anyway I received two bags in my recent purchase and one contained only 408 and another contained 109 and a few 408 and had fewer LDRs in it than the 408 bag. The 109 bag is the bag I sent out the unmatched LDRs from. I dont recall having a problem with the 109s at all. The only thing I recall is that it seemed that they would land in the 2-5k range with a 40k resistor in series with 5V and that the 408 would land somewhere in 2.5k-7.5k range. I sent unmatched out of 109 hoping that with only 25 in most orders that you guys would have a better chance finding a match knowing that they would land in a smaller pattern than the 408s. I sincerely hope that BGTs experience is not shared with everyone that got 109s from me. I have to say I am not exceedingly worried about this though as I did get many matched in that 2-5k range and with only about 350LDRs on my last batch of matching and having 3 different batches to match from I probably only had 100 or so of the 109s so I feel pretty good about the chances of people who ordered 109s.
Uriah
Uriah
George - type of ski wax to use
George,
I shall be waxing lyrical later about the LightSpeed Attenuator - but for the moment I have a question about the wax to be used to enclose the LDR's- I have found sticks (candles) of black ski repair wax which looks as though they would do the job. You light the candle and let the wax drip onto your skis (sorry LDR's) - is this OK?
Alan
George,
I shall be waxing lyrical later about the LightSpeed Attenuator - but for the moment I have a question about the wax to be used to enclose the LDR's- I have found sticks (candles) of black ski repair wax which looks as though they would do the job. You light the candle and let the wax drip onto your skis (sorry LDR's) - is this OK?
Alan
Re: George - type of ski wax to use
No Allan I think that is not wax but PTFE, used to repair ski bases and it will maybe melt the housing of the NSL32SR2S's as it has a higher melting point, just use candel wax if you have no ski base wax. Normal wax will do fine for stablizing the thermo coupling of the 4 xNSL32SR2S's
And remember not too hot wait for it to cool and get thicker before pouring it over the NSL32SR2S's
I just use ski base wax on the production Lightspeed Attenuator to make it hard for the little Asian copy cats to get into, because I've sent quite a few over there.
Cheers George
AlanElsdon said:George,
I shall be waxing lyrical later about the LightSpeed Attenuator - but for the moment I have a question about the wax to be used to enclose the LDR's- I have found sticks (candles) of black ski repair wax which looks as though they would do the job. You light the candle and let the wax drip onto your skis (sorry LDR's) - is this OK?
Alan
No Allan I think that is not wax but PTFE, used to repair ski bases and it will maybe melt the housing of the NSL32SR2S's as it has a higher melting point, just use candel wax if you have no ski base wax. Normal wax will do fine for stablizing the thermo coupling of the 4 xNSL32SR2S's
And remember not too hot wait for it to cool and get thicker before pouring it over the NSL32SR2S's
I just use ski base wax on the production Lightspeed Attenuator to make it hard for the little Asian copy cats to get into, because I've sent quite a few over there.
Cheers George