My battle with LED attenuation

[Paul Barker]

Scary, this morning it required a tweak back a little, and tonight it needs a tweek. But when balanced it seems to hold for all my listening levels, so doesn't seem to be particularly amplitude sensetive. Yet it seems to shift over time.

That would explain the accounts on the web of people returning the OEM versions which then come back balanced again.

This implies to me there is no point trying to match the LDR's, just put in a means to sort out each listening session.

For me the method I posted up here is perfect. Though I warn I have at one time had the wiper all the way one end, now it is backed off a 1/3rd of the way to middle from that extreme. I used 4k7 so I suggest a 10k pot.

Go figure, it's now near the midpoint.

Word of warning to Nick NOT WORTH OEM'ING TOO VARIABLE but reading betwene the lines I suspect Nick has evaluated and decided against. Very wise, would be tearing hair out with all the returns!

[Nick]

Word of warning to Nick NOT WORTH OEM'ING TOO VARIABLE but reading betwene the lines I suspect Nick has evaluated and decided against. Very wise, would be tearing hair out with all the returns!

Oh yes.

[Paul Barker]

I dug this out because I am missing my Stereo Coffee. The control preamp of the Sugden is hopelessly veilled compared to LDR preams.

Anyway one of my NSL-32SR's has broken off an end of the resistor.

My recommendation if you use these is to fix the leeds to a board and take the connection from there if you are using point to point wiring.

My fault, but a weakness which needs illuminating.

Now the question. As I have the Stereo Coffee there is little point me ordering another batch of 6 (minimum pack size) from RS.

So if anyone happens to have a spare, yes please?

Otherwise it's mothballs for this.

[Paul Barker]

Someone has sent me a pm because he wants to hook up a LDR attenuator.

I don't wish to engage in pm's about the matter.

I was asked:

" is that the complete circuit using the NSL-32s chips and I saw on this forum and are there any tips you could furnish me with. "

This now goes back in the dim past. But the original circuit I copied is:


and this is how I made it so that I could balance the channels.



Ed has explained that the shunt element is not in balance.

This hasn't affected my enjoyment at any level.

I now use the Stereo Coffee which is so cheap it isn't in my opinion worth scratch building. It is perfectly balanced and remains so. Obviously if you have your own components already or are limited for pennies the information is in this post which you require.

Apparently there is some distortion with LDR attenuators, inspight of which they sound better to me than anything else I have tried.

[Greg]

Apparently there is some distortion with LDR attenuators, inspight of which they sound better to me than anything else I have tried.

Oh yes, I certainly share that observation. I will be working to get my own six input Stereo Coffee introduced into the pre amp section this weekend. I'll report back once done although I suspect certain prejudice here may make my comments worthless because it apparently tested badly. The biggest disappointment to me that having been tested and shown to introduce loads of noise/ interference, the tester was not willing to give a simple opinion on how it actually sounded. A great shame, but maybe indicative of someone moving out of DIY and moving on into commercial production.

The Stereo Coffee may well be noisy, but probably so was my valve Cathode Follower Pre. Without doubt, the SC is a significant improvement and that is why I'm going this way.

[rowuk]

.....The biggest disappointment to me that having been tested and shown to introduce loads of noise/ interference, the tester was not willing to give a simple opinion on how it actually sounded. A great shame, but maybe indicative of someone moving out of DIY and moving on into commercial production.

Come on Greg, let go. There is no rule that we have to post everything that we experience. We are happy for you and Paul. I am disappointed that you try to "force" your agenda on others again. Your last sentence is an incredibly cheap shot against a member of the forum in top standing.

Nick has been more than forthcoming on so many issues and I am sure that he has his reasons to ignore your baiting. Why should he even get into a discussion? Would it change anything? I think not. Saying nothing is often better than managing unflexible terrain. The Stereo Coffee is cheap enough and we are all big enough to make up our own minds.

I do not suspect any commercial motives behind his leaving your thread. The tone of the thread got out of hand when it turned into win or lose. Now you are starting in this thread. I am more concerned that he will not publish any more of his personal results because of certain attitudes here. I do value his neutrality in many issues.

He was the ONLY one that actually published real measurements of the thing. No conclusions were drawn or implied. No one screamed "eureka" or started pointing fingers. The manufacturer even said that they would look at the issue and respond favorably to customers. THAT is fantastic.

Actually, if you read a couple of pages back in this thread, he has already discussed his experiences - before anyone could accuse bias due to measurement results or his commercial activities.

[Paul Barker]

......The biggest disappointment to me that having been tested and shown to introduce loads of noise/ interference, the tester was not willing to give a simple opinion on how it actually sounded. A great shame, but maybe indicative of someone moving out of DIY and moving on into commercial production.

Please clean up your quote so it doesn't reference the above statement to me?

[Cressy Snr]

May I say that I have nothing against the designers of this LDR gizmo, who I am sure are a very nice, well-meaning body of men, but "Stereo Coffee" as a name just irritates the hell out of me.

It has the same effect on me as that pink-shirted, condescending gobshite who says:

"Don't you know you could be due PPI compensation!
Not interested?
Banks have set aside billions of pounds, yet you've still done nothing about it?"

Gives me an overwhelming urge to kick the TV screen

All In my purely subjective opinion of course

[IslandPink]

All I can say is, I think there are cases where persistence doesn't pay off.

[rowuk]

......The biggest disappointment to me that having been tested and shown to introduce loads of noise/ interference, the tester was not willing to give a simple opinion on how it actually sounded. A great shame, but maybe indicative of someone moving out of DIY and moving on into commercial production.

Sorry Paul, done.

[rowuk]

Well, getting back to the thread subject, I like what Paul did - a very efficient, non intrusive method to balance dislike devices. Added benefits are the possibilities to balance other issues in playback.


What I would really like to know is if it is the photocell or LED that is not linear. We could built a discrete device with 2x (one normal LED - or other light source and two photocells) if it is only the LED. Then we would have the stereo channels with a common lightsource/driver.

[Paul Barker]

These two types discussed here don't use seperate photocell and LED. They both use an integrated unit.

IF I remember rightly the first person to discuss this idea in the diy domain was using a black tube with one component at each end. He adjusted the distance to match the channels. I have not tried that way.

[Greg]

.....The biggest disappointment to me that having been tested and shown to introduce loads of noise/ interference, the tester was not willing to give a simple opinion on how it actually sounded. A great shame, but maybe indicative of someone moving out of DIY and moving on into commercial production.

Come on Greg, let go. There is no rule that we have to post everything that we experience. We are happy for you and Paul. I am disappointed that you try to "force" your agenda on others again. Your last sentence is an incredibly cheap shot against a member of the forum in top standing.

I have no agenda on this. It is after all, someone else's product and I have no connection with that person other than through trading. My disappointment that Nick was unwilling to offer a subjective observation on sound quality was based on the fact that I have known him for a long time and in the past he would readily comment on such matters but now apparently is unwilling to. Because I trust his ears, that unwillingness has compounded the disappointment. Something has changed and I hedged a consideration on what that change might be.

Nick has been more than forthcoming on so many issues and I am sure that he has his reasons to ignore your baiting. Why should he even get into a discussion? Would it change anything? I think not. Saying nothing is often better than managing unflexible terrain. The Stereo Coffee is cheap enough and we are all big enough to make up our own minds.

The use of the term 'baiting' is inappropriate, inflammatory and wrong.

I do not suspect any commercial motives behind his leaving your thread. The tone of the thread got out of hand when it turned into win or lose. Now you are starting in this thread. I am more concerned that he will not publish any more of his personal results because of certain attitudes here. I do value his neutrality in many issues.

you are wrong. It never was my thread, and in any case, nothing got out of hand. At the time, Nick simply didn't need the grief and I have privately dealt with that.

He was the ONLY one that actually published real measurements of the thing. No conclusions were drawn or implied. No one screamed "eureka" or started pointing fingers. The manufacturer even said that they would look at the issue and respond favorably to customers. THAT is fantastic.

agreed. Chris from Stereo Coffee has assured a customer support at the very best level.

Actually, if you read a couple of pages back in this thread, he has already discussed his experiences - before anyone could accuse bias due to measurement results or his commercial activities.

Sorry don't understand that. Please be more specific.

Ps. What is your real name?

[Greg]

IF I remember rightly the first person to discuss this idea in the diy domain was using a black tube with one component at each end. He adjusted the distance to match the channels. I have not tried that way.

Well you have because that is exactly how the Stereo Coffee LDR's are constructed.

[Neal]

IF I remember rightly the first person to discuss this idea in the diy domain was using a black tube with one component at each end. He adjusted the distance to match the channels. I have not tried that way.

Morgan Jones?