If you want to use LDR's , as I observe in other designs, they find it easy to both achieve silence at zero volume, and to also have as many inputs, as are required.
Are there passive attenuators that don't zero volume and only offer one input ?
I am not sure how many people would like those features, but its worth asking in case someone would try to sell such a thing.
Which is to say it is essential I should think to be able to zero volume, and have more than one input, do you agree ?
Which is to say it is essential I should think to be able to zero volume, and have more than one input, do you agree ?
Showing 21 responses by dbxrecord
The op wants a passive pre with one input, that doesn’t go to zero, all the ones mentioned above do zero the volume. Quite the opposite actually. Referring to my first post, it can be seen not being able to zero volume, or have more than one input, is not desirableat all. Both are serious compromises, that designs must overcome. |
The S3 's are widely all over the place, almost impossible to get few "quad matched sets" to do a Lightspeed properly with close to zero volume low volume, unless they are forced matched with servo feedback arrangement and by over driving some which "raises the distortion substantially" to meet the others which will kill them over a very short period. Actually the SR3 are better in my experience than the SR2S for matching. There is no need either, to use servo feedback arrangements. Keeping current 3ma for the whole circuit is the key. Sweeping between lowest volume and highest should achieve variance of just 2.78ma to 3ma , for the entire circuit, encompassing the load of 4x NSL32SR3 There is no need to go any higher at all, which keeps distortion extremely low, and achieves much better stability with cell resistance. R(on) of 20ma per device, or anywhere near that figure, is thus neatly avoided . |
The S3 ’s are widely all over the place, almost impossible to get few "quad matched sets" to do a Lightspeed properly with close to zero volume low volume, unless they are forced matched with servo feedback arrangement and by over driving some which "raises the distortion substantially" to meet the others which will kill them over a very short period.I have no association with either name, please stick to the subject rather than libel. |
True but it's not as pure a signal path. I have owned my LDR passive (Lightspeed) for over 10 years. I have also built/owned other resistor and transformer based passives. The simplicity of the Lightspeed and the ability for it to stay out of the way more so than the other passives is why But what I observe is other LDR attenuators, based on what I have learned may be the NSL32SR3 type of LDR, apparently these can offer better audio characteristics, namely lower distortion, the manufacturer Luna Inc stating "best distortion characteristics" and also as I understand, providing wider resistance range. Apparently they are also able to easily zero volume with a clever technique, and offer more than one stereo input, as I understand as many inputs that are needed, can be catered for. It would seem then easy enough to solve, not to have problems like not being able to zero volume, if designs, and designers, have motivation to do so. The one you mention appearing after so many years, to lack any motivation whatsoever, to overcome the two said issues. |
I said.If you read the first post it asks a question. Am i right in assuming you are you somehow totally OK, with all passive preamps not being able to zero volume and offering one input ? The discussion points, that its not too hard to do, even with LDR types. I really hope not, rather hopefully your response would be on reflection, that would be much better for all passive preamps to have silence at zero volume, and offer more than one stereo input. The question is there for all to respond to, perhaps we can see from others contributing, that not being able to zero volume and only provide one input is really undesirable, in fact dreadful, now knowing its easy to correct. It remains for those marketing passive preamps, that it is quite easy to turn around, to be a success story instead, and that is what the thread is all about.... improving what is out there. |
This is BS, do your own homework. First off observe the incivility of language being used in the first paragraph, and the attitude of demeaning. He would do well to learn to tackle the subject, & not the writer. Lets look at the subject. The manufacturer Luna inc states for the NSL32SR2S " low distortion" , and for the NSL32SR3 " best distortion characteristics " best, in my dictionary The Concise Oxford has the following meaning: " of the most excellent, or outstanding, or desirable kind " The second part of his reply, its easy to assess that pricing of goods of any business relates to the number of units being sold. Indeed the SR2S is more expensive as a direct result of fewer being stocked and one would have to then think units sold, a weak point in his reply to raise. Trying as we see, to attribute higher cost, as being better. As example today DigiKey stocking 13611 of the SR3, and just 897 of the SR2S. but lets go on, he states as we see doesn’t go low enough in volume unless over powered/stressed and won’t last if done so.He refers here to 20 ohms of difference that the SR2S has when powered with 20ma of current, vs the SR3, his attribution being needed to go low enough in volume. Herein the problem, finally exposed, deep breath ... one does not need to raise current, to achieve low or zero volume with LDR's. In fact other designs achieve current draw of no more than 3ma total at all volume levels which includes the entire circuit, with the benefit of no stress at all, to the LDR's Another issue being lowering shunt resistance too low, appeasing to achieve low volume, does nothing, other than squashes available dynamics in music. It is far better to have a higher resistance to begin the shunt resistance range, with the NSL32SR3 its possible though to have 100 ohms at zero volume, and 56k by mid volume with the shunt pair , and to have 25 mega ohms at zero volume with the series pair and 18k at mid volume. That though does take quite a bit of design effort.... but it can be done. Other designers providing LDR attenuators worked this out many years ago how to zero volume, and to provide more than one stereo input, without using higher current , they even went to the trouble of publishing how to do it, for everyone's benefit. |
You’ve been caught out sunshine, you want more posted up from diyaudio alsoMaybe deal with the topic instead , refer to post 1 if you need to. |
@dbxrecords ....why not just disclose or post under your industry affiliation?If this thread is anything to go by, it is obvious a code of ethos is desperately needed. Until then, sorry but few would submit themselves to such abuse. Let alone give up personal information, to be potentially subjected, to more of the same. Here as example is a forum with a code of ethos, that is good to reflect on: https://theartofsound.net/forum/showthread.php?17-The-basics-of-Ethos |
How’s that for a outright lie!! How does he live with himself? Chris! you are certifiable. If you choose to spell my name wrongly, I have no obligation to agree to that mistake, I would expect you to do the same, not acknowledge your name being spelt wrongly - as would anyone. Please once again, stick to the subject. If you have nothing to contribute then don't contribute. I can say, all my passive attenuators are able to zero volume, and I enjoy 6 contact less stereo inputs , that is if you need any further reminding of what the thread is about. Just this morning I enjoyed radio on one input, then switched to a jazz CD, and to a hard disc recorder for some Pink Floyd, I did not have to change cables at all. |
No. Is it HiFi or sonic wallpaper?If it is contact less already on the signal path then you can have as many inputs as required, and zero volume too. To do that arrange LDR anodes of each series pair to be switched on in turn - according with your stereo inputs. To zero volume needs your design to power shunt anode separate to series anode, it needs also NOT to ground the LDR cathodes, rather arrange a regulated jfet current sink. Your volume control is arranged between shunt cathode and series cathode. You then arrange via LM317, with a higher potential on its adjustment terminal, place its Vin to the series cathodes and adjust for silence with resistance from the higher potential to Adj. As lower volume positions are reached, the start circuit thus named influences the series resistance readings, and causes extreme resistance on series pair at lowest volume, creating ability for silence. The start circuit is accompanied with another circuit called the continue together they interact together to improve relationship of the entire circuit for excellent current delivery and resulting audio performance. |
Please stick to the subject, rather than further libel, the subject is Are there passive attenuators that don't zero volume and only offer one input ? I am not sure how many people would like those features, but its worth asking in case someone would try to sell such a thing.Which is to say it is essential I should think to be able to zero volume, and have more than one input, do you agree ? |
Why an A/C supply when a DC wallwart would keep all hum outtadabox?Because you then avoid the cheap rectification components inside wall warts, all avoided by using a AC 12v supply. Rectification can then be achieved with thyristors, and jfets https://www.stereo.net.au/forums/topic/113297-comparison-lightspeed-diy-ldr-pre-vs-stereo-coffee-diy... |
I am happy to ignore that reason, as it has absolutely no relevance at all, relating to what customers want from passive attenuators. We each know LDR passives offer so much better audio than other attenuation methods, and the task ahead is to make LDR passives the number one choice, as nothing else, can do what they do. The good news is each issue, namely more inputs and silence are relatively easy to do. I am very sure your customers will welcome those new features, and thank you, for caring about their needs., on a wider perspective ... it will see see all other passives, .. eating dust. |
High quality DC supplies are 10 a penny today.Look inside the plugpack , it explains why they are 10 a penny. "A thyristor is a semiconductor device which can be used to switch current on and off. When used in rectifier circuits, thyristors allow current to be controlled more accurately than diodes, which can only be ON or OFF. A thyristor can be triggered to allow current to pass in a graduated manner, by firing (switching on the thyristor) at a precise time, therefore controlling the conduction angle." https://www.ppi-uk.com/news/thyristor-controlled-rectifiers/ |
There is no doubting LDR passives for sound quality are the bargain of the century, surpassing every other device you can name. I am unsure if everyone would put up with one input and not being able to zero volume, particularly knowing that those two aspects can be solved. The product IMO must surpass with its features too, ideally one step ahead in all departments, making it irresistible. |
±0.1VDC 1mVDC ripple is hardly anything to sneeze at.No thyristors are ideal in this circuit as they exhibit much better complete switching. As you well know There are hundreds if not thousands of thyristors , each with different characteristics suiting different purpose, To which do you refer ? The main advantage with thyristors in rectifier circuits as you should know, is to conduct current only in one direction,this suits when the load requires DC. A diode in comparison always has a forward voltage droprelated to temperature so is always incomplete with its switching. In so doing it creates what is called dark current, also called reverse bias leakage current. With thyristors they too can exhibit forward voltage, however is related to the junction current, With 3ma being the load that does just not occur, But if large current is the load seen by internal junctions then the thyristor does such transfer to exhibit forward voltage drop slowly. Another major asset being that a thyristor is a controlled device vs uncontrolled |
Not at all, if you check back through each post I have not mentioned other manufacturers product name, or personal names, and I have also avoided, as best I can, stating my own. This page being the exception. Think of other manufacturers of passives, rather than the one you refer to, and it all begins to make sense. Let's hope things improve, so all passive manufacturers move forward & cater for features that make passives, the only choice. |