Bobken said:
You make some good points, but they are at odds with the switches we have been using for the past 13 years. All of ours have gold-plated copper posts with silver "caps" welded on top.
But no need to fret about it. I'll just e-mail the head engineer there and ask him if any models have ever used silver posts. And it may also be that you had a different switch. There was apparently some business difficulties that resulted in the original switch company, Shallcross, being left by the person who founded it and he later founded Shallco. So there could be some room for confusion here. I'll see what I can find out to clear it up.
Hi John,
You have to admit that the report you did post (and thank you for that) had enough ambiguity so that it really didn't have useful information.
As for research, the reason I asked you in the first place was that you had an opinion, and you normally have a good reason for an opinion. Not once have I ever asked you to research something for me either.
I really do a ton of my own research. Unfortunately, everything I find out, you have done 25 years ago. Now, that was sarcasm.
-Chris
Hmmmm. You know, I simply asked if you knew off hand.
You have to admit that the report you did post (and thank you for that) had enough ambiguity so that it really didn't have useful information.
As for research, the reason I asked you in the first place was that you had an opinion, and you normally have a good reason for an opinion. Not once have I ever asked you to research something for me either.
I really do a ton of my own research. Unfortunately, everything I find out, you have done 25 years ago. Now, that was sarcasm.
-Chris
Please understand, that about 30 years ago, Dick Marsh (audio designer), Peter Moncrieff (audio publisher), Karen Richardson (audio reviewer), and I participated in a listening test. One of the objects of the listening test was the mercury contacts themselves. We came to a negative conclusion together. The Spiegel Box was one of the first ABX boxes made for evaluation of audio equpment. Spiegel apparently gave up on audio for some reason.
Hi John,
That's fair enough.
I think that the conclusion reached was probably not something you would stand by. There are too many other factors at play here with the quoted test. I can't imagine you testing any other component (resistor/capacitor/switch ...) this way. That is the reason I had asked if you had looked at mercury switches any closer.
So, it appears as though a mercury relay may possibly be okay. A moot point because I doubt you could sell such a device to consumers these days. Your customer base had better be military I guess if anyone where to use these.
It ain't worth pursuing any further.
-Chris
That's fair enough.
I think that the conclusion reached was probably not something you would stand by. There are too many other factors at play here with the quoted test. I can't imagine you testing any other component (resistor/capacitor/switch ...) this way. That is the reason I had asked if you had looked at mercury switches any closer.
So, it appears as though a mercury relay may possibly be okay. A moot point because I doubt you could sell such a device to consumers these days. Your customer base had better be military I guess if anyone where to use these.
It ain't worth pursuing any further.
-Chris
There is/was Shallco/Shallcross, Tech Labs and Daven (a few less common as well)... all making a similar product. There are some others that make a switch for the military similar to the switch product that Charles and others are using now... have to grab some to see what names are on them.
My experience is that they are made by similar means, but the materials do vary, both by manufacturer and by time - also by specification.
Most of the modern switches seem to have a rather thin top contact layer. Older switches seem to have rather fatter top layers. The oldest rotary step attenuators that I have in my collection have positively thick silver contacts, like 0.125" or better thick. The ones I see today seem to be more like 0.01" thick.
I do not think they use pure Ag in the contact area - too soft. I think it is an alloy. Which alloy, I am not sure. Today with thinner contacts, a harder alloy I suspect. The older one that I refered to looks visually different, and is likely a different and maybe "purer" alloy. Also I base this on the wear pattern being deeper into the contact itself. The newer ones don't seem to show such a deep wear pattern no matter how much they were used (radio station consoles anyone?)
The oldest ones seem to have the contact "rivet"/stake made from the same material as the contact. Later examples seem to be more variable, and many are merely plated copper or brass, not solid silver anything.
I prefer the older rotary step attenuators, as these have fat diameter contacts with thick contacts as well... I don't prefer those dainty little contacts...
<end core dump>
Alan, answer me this, what does an IROC or Nascar driver tell the pit crew when he comes in to the pit about how the car is performing? What is the difference between the #1 car and the #2 car for any given race team (are the cars identical?), do they perform identically?
_-_-bear
My experience is that they are made by similar means, but the materials do vary, both by manufacturer and by time - also by specification.
Most of the modern switches seem to have a rather thin top contact layer. Older switches seem to have rather fatter top layers. The oldest rotary step attenuators that I have in my collection have positively thick silver contacts, like 0.125" or better thick. The ones I see today seem to be more like 0.01" thick.
I do not think they use pure Ag in the contact area - too soft. I think it is an alloy. Which alloy, I am not sure. Today with thinner contacts, a harder alloy I suspect. The older one that I refered to looks visually different, and is likely a different and maybe "purer" alloy. Also I base this on the wear pattern being deeper into the contact itself. The newer ones don't seem to show such a deep wear pattern no matter how much they were used (radio station consoles anyone?)
The oldest ones seem to have the contact "rivet"/stake made from the same material as the contact. Later examples seem to be more variable, and many are merely plated copper or brass, not solid silver anything.
I prefer the older rotary step attenuators, as these have fat diameter contacts with thick contacts as well... I don't prefer those dainty little contacts...
<end core dump>
Alan, answer me this, what does an IROC or Nascar driver tell the pit crew when he comes in to the pit about how the car is performing? What is the difference between the #1 car and the #2 car for any given race team (are the cars identical?), do they perform identically?
_-_-bear
Hi John,
These days I depend heavily on the spell checker in my browser (FF3). I am smart enough to allow it to overrule me, but there are times .... Darn computers!
Hi Bear,
You should see the contacts on the resistance / RTD boxes. The most common reason for these to be out of tolerance are the contacts. That's if the low value resistors aren't cooked. I do know these have solid contacts on them. I'd have to open one up to have another look. I guess that's why these things are always over $1 K to buy.
-Chris
That's what I thought!
These days I depend heavily on the spell checker in my browser (FF3). I am smart enough to allow it to overrule me, but there are times .... Darn computers!
Hi Bear,
You should see the contacts on the resistance / RTD boxes. The most common reason for these to be out of tolerance are the contacts. That's if the low value resistors aren't cooked. I do know these have solid contacts on them. I'd have to open one up to have another look. I guess that's why these things are always over $1 K to buy.
-Chris
anatech said:
Exactly! You've hit on the source of the unpleasantness that takes place here every day.
Guys like John Curl, Charles Hansen, or Nelson Pass (to name just some already mentioned on this page) describe something that they have done the work to gain first hand knowledge about. Then other people poke holes in it, often without making any effort to gain that first hand knowledge for themselves.
It rarely is "Gee, I tried that and got different results and here's what I think about that."
Or even "Gee, I tried that for myself and got different results. I have no idea why. Anybody have some ideas?"
Instead it's just rock throwing.
So the guys who have done the experiments take some offense to being attacked and often feel they have to defend themselves. Often against people who haven't done the work and are just taking the chance to throw rocks at whom they may perceive to be easy targets. This is the internet where most people use aliases and are at a distance, after all.
Chris, I am not picking on you - you just happened to offer the insight.
Back to radio silence.
Charles Hansen said:
Hi Charles,
I fully agree that there is no need to fret about anything here which was why I said "for what it matters", but I am not happy to provide others with inaccurute information, even unwittingly, if this can be avoided.
If there had been any uncertainty and I had not carried out the tests I did many years ago, I would have said "I believe" etc., instead.
I think Bear has found the answer here when he refers to switches made at different times, and like me he appears to believe the posts which I filed down are the same solid (silver-alloy) material. I have checked a switch in use with a magnet, and they are not nickel, anyway. I also am sure that the silver used will be some kind of alloy and have never implied otherwise, because pure silver is extremely soft and it is difficult to work-harden this metal through hammering, rolling or whatever, unlike many base-metals.
Those switches which I referred to were originally made up in quantity and supplied to Audio Synthesis in the UK maybe 20 or so yrs ago, and they have really 'butch' contacts if that helps with your enquiries to Shallco. They are stamped "Shallco Inc. Smithfield, N.C. USA", and designated 12735-2 9633.
It is rather academic now, but I would be pleased to hear of any outcome as it doesn't seem like current versions are made in quite the same way.
Irrespective of the outcome here, the overal engineering simplification, short signal-path and high-quality materials used in these excellent-sounding switches, when compared with the small-signal relays which are generally available, is I am sure the main reason for the difference in their sonic 'attributes'.
On the same question of mis-information, in my earlier post I should have said "silver sulphide" and not " silver sulphate" which must have been the result of posting long after an old man's sensible bed-time!
Regards,
Chris,
I am curious about your experience with the decade resistance boxes (that's what ur talking about?). I would think that after a few turns back and forth of the switches that the switch would be cleaned, and the values back in tolerance. Unless of course we're talking an antique where the contacts have a thick black coating on them?
Afaik, that's the whole principle behind the silver wiping contact type switch...
Oh, btw, there is another issue with them, that is that there are two (or more depending on the switch) wiper contacts that are spring loaded, and they ride on an arm that may be made from "whoknowswhatium" and may or may not include brazed, welded, staked or soldered connections too... let's not forget that part!
_-_-bear
I am curious about your experience with the decade resistance boxes (that's what ur talking about?). I would think that after a few turns back and forth of the switches that the switch would be cleaned, and the values back in tolerance. Unless of course we're talking an antique where the contacts have a thick black coating on them?
Afaik, that's the whole principle behind the silver wiping contact type switch...
Oh, btw, there is another issue with them, that is that there are two (or more depending on the switch) wiper contacts that are spring loaded, and they ride on an arm that may be made from "whoknowswhatium" and may or may not include brazed, welded, staked or soldered connections too... let's not forget that part!
_-_-bear
Bobken said:
Hi Bobken,
Here is the full text of the reply I got from the lead engineer at Shallco:
~~~~~~~~~~
I have been here almost 25 years and I have never seen any contacts with
solid silver turrets (posts). At one time, there were solid silver contacts
used on some attenuators, but we only supply silver headed contacts
now. (In order to get solid silver contacts (rivet type), there would have
to be a special run that would be very expensive.
If he has one, I didn't have anything to do with the design which means it
would have to be quite old.
~~~~~~~~~~
When he says "attenuators", he means the pre-built rotary switches that already have resistors attached and are in an enclosure of some sort. (I've only seen pictures and never one in person.) So either you had an "attenuator" or something really old. But obviously if they used solid silver turrets in their attenuators, they probably also used them at some point in at least some of their rotary switches, so perhaps you have a really old sample that had solid silver turrets.
The good news is that the current switches have very thick silver "caps" welded onto the copper posts, so they will last a very long time. We have have had units in the field for over 10 years come back with only negligible signs of wear. And better yet, they are still incredibly sonically transparent. In my listening tests they were essentially indistinguishable from a bypass.
The listening tests were carefully designed and conducted. We put two connectors back-to-back between the preamp and amp with two pieces of (Cardas) wire between. Then the pieces of wire were either soldered to each other, or soldered to the DUT. That kept the number of connectors and solder joints identical for each DUT and the reference bypass of just the wire. In addition to the Shallcos, we tried a half-dozen different relays but they were all grossly colored by comparison.
Looking back on my early work on switches and relays regarding ABX boxes, I find the same polite questioning, (and dismissal) by Lipshitz et al, on ANYTHING that we found.
For example, they JUMPED on the idea that we had used the mercury switch based Spiegel box for our listening evaluation of two preamps as described by Dick Marsh in an LTE,in 1/80 of 'The Audio Amateur'. You should understand that we did NOT use the mercury switch ABX box for our ABX test, but we took it to the test to note the difference when using it. We could actually do an ABX on the mercury relay contacts themselves, using a silver switch as the switcher, and get meaningful results. They were that obvious.
However in TAA, 3/80, Lipshitz et al, stated: "The Marsh ... double blind preamplifier comparison test (p.65) is significant. Although this was not mentioned, it was, we believe, conducted using Dave Spiegel's double blind A/B/X box. This is itself is important, since it implies that the authors were satisfied that this box did not affect the sound in any audible respect, in marked contrast to the as-yet-unsubstantiated claims made by JWC in 'The Absolute Sound' about the degradation in sound quality caused by the same box." ref. TAS Vol. 4 #13, 1978 pp. 5-6 ...
THIS IS PATENTLY INCORRECT! We didn't use the Spiegel box in the test, except as a test object. Did Lipshitz check with us? NO! As is typical of many who don't believe that significant differences occur anyway between audio components. They just stated their opinion that 'we' had found that the mercury relays were inaudible.
It gets old, and was somewhat disappointing even then, almost 30 years ago.
For example, they JUMPED on the idea that we had used the mercury switch based Spiegel box for our listening evaluation of two preamps as described by Dick Marsh in an LTE,in 1/80 of 'The Audio Amateur'. You should understand that we did NOT use the mercury switch ABX box for our ABX test, but we took it to the test to note the difference when using it. We could actually do an ABX on the mercury relay contacts themselves, using a silver switch as the switcher, and get meaningful results. They were that obvious.
However in TAA, 3/80, Lipshitz et al, stated: "The Marsh ... double blind preamplifier comparison test (p.65) is significant. Although this was not mentioned, it was, we believe, conducted using Dave Spiegel's double blind A/B/X box. This is itself is important, since it implies that the authors were satisfied that this box did not affect the sound in any audible respect, in marked contrast to the as-yet-unsubstantiated claims made by JWC in 'The Absolute Sound' about the degradation in sound quality caused by the same box." ref. TAS Vol. 4 #13, 1978 pp. 5-6 ...
THIS IS PATENTLY INCORRECT! We didn't use the Spiegel box in the test, except as a test object. Did Lipshitz check with us? NO! As is typical of many who don't believe that significant differences occur anyway between audio components. They just stated their opinion that 'we' had found that the mercury relays were inaudible.
It gets old, and was somewhat disappointing even then, almost 30 years ago.
Hi Charles,
Thanks for discovering this, which is interesting to know.
There seems to be some possible slight misunderstandings apparent from the reply, and these switches I used are certainly not Shallco made 'attenuators', as the reply suggests.
They are 32-step rotary switches as previously described which were made up in large quantities for Audio Synthesis in the UK, and they used these for various purposes including at one time their own highly-regarded manually-operated stepped attenuators originally around 20 or more yrs ago IIRC. I guess that they would have been ordered in thousands, rather than in hundreds, but I never asked.
I purchased a handful of these switches direct from Audio Synthesis as they were the only UK Shallco supplier, and used them for my own purposes including for some vishay-based attenuators which were what I commented on.
As the replier mentioned, these are a quite old design and most likely bespoke made for A/S so it still seems most probable that these 'turrets' are solid silver (alloy) as with the rings which they are attached to. I guess I will never know for sure about the other contacts as there is solder on the tag ends which will prevent any positive acid tests on those switches I have in use.
However, for present/future purposes, this is of little consequence as current versions are apparently not constructed in the same manner.
Thanks again for the investigation work, anyway.
Regards,
Thanks for discovering this, which is interesting to know.
There seems to be some possible slight misunderstandings apparent from the reply, and these switches I used are certainly not Shallco made 'attenuators', as the reply suggests.
They are 32-step rotary switches as previously described which were made up in large quantities for Audio Synthesis in the UK, and they used these for various purposes including at one time their own highly-regarded manually-operated stepped attenuators originally around 20 or more yrs ago IIRC. I guess that they would have been ordered in thousands, rather than in hundreds, but I never asked.
I purchased a handful of these switches direct from Audio Synthesis as they were the only UK Shallco supplier, and used them for my own purposes including for some vishay-based attenuators which were what I commented on.
As the replier mentioned, these are a quite old design and most likely bespoke made for A/S so it still seems most probable that these 'turrets' are solid silver (alloy) as with the rings which they are attached to. I guess I will never know for sure about the other contacts as there is solder on the tag ends which will prevent any positive acid tests on those switches I have in use.
However, for present/future purposes, this is of little consequence as current versions are apparently not constructed in the same manner.
Thanks again for the investigation work, anyway.
Regards,
Charles Hansen said:
Hi Charles,
Thanks for describing your listening tests. This is an area of great interest for me, but often people don't say much about the details and how or whether anything is controlled. What you describe sounds like a good test.
Could you elaborate on some of the details, both electrical and procedural?
For example, it sounds like the electrical arrangement had the DUT in series, probably sourced from a low impedance and sunk into a high impedance. That kind of an arrangement would usually tend to minimize any of the conventional distortions we might measure, but could you share your thoughts on that and mention the impedance levels?
On the procedural side, there are the usual questions about what measures may have been taken to control the tests. For example, how many people listened at a time, did any of the listeners have knowledge of what DUT was being tested, were the DUTs exercised during the test in a way that would create a sound, who changed the DUT, was that person in the room with the listeners, etc.?
Thanks,
Bob
Hi Charles,
Bob has reiterated what I was trying to get at. The test itself that clearly showed what the controlled parameters were. That is the kind of information that validates the stated results of a test.
Thank you.
Hi John,
Now, considering that you are equating people here with Mr. Lipshitz, that is a nasty comment (although I wish I had his grasp of mathematics).
There has got to be a reason why you get similar reactions from many different people, and you have to admit that you aren't the easiest person to talk with either. Why not assume people are curious, rather than trying to find fault with your work?
So John, you have completely answered my question, and I'm satisfied with your answer. Thank you for explaining it.
-Chris
Bob has reiterated what I was trying to get at. The test itself that clearly showed what the controlled parameters were. That is the kind of information that validates the stated results of a test.
Thank you.
Hi John,
I stopped attending AES here due to Mr. Lipshitz and his approach to other people. Math is his thing and he likes to argue from that perspective - only. Then he walks away all smug after confusing most people there. Like he's always in a contest to be more right than anyone else. He has his place, and that place is not in applied audio electronics. He stifles most discussions unless you can converse completely through math. He's a little guy too. Maybe that's why he is the way he is.
Now, considering that you are equating people here with Mr. Lipshitz, that is a nasty comment (although I wish I had his grasp of mathematics).
John! That is what I wanted to know! Right there, thank you. Had you mentioned this earlier we wouldn't have had to ask for more information. You knew this, how did you expect anyone else to know without you telling us. I can also understand why you may have been taken to task for the test. You did not report fully the nature of the experiment. That is your responsibility when you report on anything, so you can't blame anyone for having the wrong impressions if you leave out important information.
There has got to be a reason why you get similar reactions from many different people, and you have to admit that you aren't the easiest person to talk with either. Why not assume people are curious, rather than trying to find fault with your work?
So John, you have completely answered my question, and I'm satisfied with your answer. Thank you for explaining it.
-Chris
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