bear said:
The premise that this thread was only about a preamp seems to have been lost a long time back. The thread was not started and does not continue to exist based on any premise that I or anyone else can hear specific diferrences beteween any parts components or external cables etc. It is an interesting thread that has a life all its own. Any particular reason why you pointed this question at me? Have I upset you or offended you somehow? I wont say anything on hearing differences because I don't intend to get into any kind of argument about it.
Quote
The ENTIRE output impedance of the JC-1 is .045 ohm, as measured by 'Stereophile', so we must use a pretty good relay.
Unquote
Clearly, a lot of negatie feedback is being applied.
The ENTIRE output impedance of the JC-1 is .045 ohm, as measured by 'Stereophile', so we must use a pretty good relay.
Unquote
Clearly, a lot of negatie feedback is being applied.
Hi,
At risk of accusations of self-promotion, but in the hope that it may be of interest to those using relays in audio applications, the following response I posted last year in another thread might be of some value.
The relays suggested would be suitable for low-level signals such as expected in a Blowtorch (which was what this thread was about) but not suited to higher-current applications like the output relays in power amps which have recently been discussed.
My comments on the internal construction of relays hold good for all such relays used in the signal-paths in audio equipment, of course.
quote:
Originally posted by Giordano
Bobken, I would be very interested in the remote controllabe volume control you mention !
Thanks,
JG
Hi Giordano,
Although I would like to help with this, I am unable to reveal any very specific details of this remote attenuator. It was a design which was commissioned by another UK company, and which will go into production later this year.
One thing I will say, though, is that I 'listened' to many different relays before finalising this top-quality (cost no object) design, and more importantly (destructively) took apart any which were worthwhile using from the 'sonic' aspect, to inspect their internal constructions. This is important to ensure that they enjoy a long service life without any serious sonic detereoration, as I have discovered problems in this regard over the years.
Most relays have internal parts made of dissimilar metals, simply because some parts need to be springy, and others like contacts need to be hard and resistant to arcing, oxidation and wear etc.
Some contact detereoration happens over time even with the best totally-enclosed or inert-gass-filled relays, unfortunately, but this is not the only issue here.
I don't recommend using any relay for this purpose which has any internal parts riveted together, as this can give rise to later problems. All internal parts should ideally be spot-welded or friction-welded, so that there are no metal-to-metal junctions where any corrosion or other fouling can intervene *between* the parent metals.
It is said that whenever parts are securely clenched, crimped or riveted together, this will exclude all possibility of future corrosion as the air is excluded and the parts virtually weld themselves together.
However, this is another less well-appreciated 'theoretical oversight', as I have seen for myself when dissembling some of these relays. Perhaps the makers haven't taken the trouble which I have gone to in inspecting these parts after a period in service! Also, don't forget that many of these relays are originally designed for telecoms usage, but this application may not require the same overall bandwidths which we are interested in here, and in my experience it is important to maintain integrity to many times higher than our normal upper hearing threshold.
If you carefully separate the parts and inspect the junctions through which the signal needs to pass, there will frequently be some very obvious discolouration/oxidation or whatever, which is highly resistive, and non-linear in this regard. It cannot be seen until the parts are separated, and I believe this results from galvanic reactions, or something similar, when currents pass though dissimilar metal 'junctions', but whatever the reasons for this, the result is undesirable.
Incidentally, one Omron relay I tried was up with the best, and this was their High-Isolation G6A-BS series, with bifurcated (dual) contacts OK for use down to 10uA @10mV DC, and max. contact resistance of merely 50mOhm. These are rather noisy, only from the mechanical aspect, when they switch, resulting from the more positive switching and higher contact pressures used than in some other relays, but this is good for the audio sound, though. They are not suitable for high current applications.
Another quite good choice is the Panasonic DS Series.
Regards,
__________________
Bob
At risk of accusations of self-promotion, but in the hope that it may be of interest to those using relays in audio applications, the following response I posted last year in another thread might be of some value.
The relays suggested would be suitable for low-level signals such as expected in a Blowtorch (which was what this thread was about) but not suited to higher-current applications like the output relays in power amps which have recently been discussed.
My comments on the internal construction of relays hold good for all such relays used in the signal-paths in audio equipment, of course.
quote:
Originally posted by Giordano
Bobken, I would be very interested in the remote controllabe volume control you mention !
Thanks,
JG
Hi Giordano,
Although I would like to help with this, I am unable to reveal any very specific details of this remote attenuator. It was a design which was commissioned by another UK company, and which will go into production later this year.
One thing I will say, though, is that I 'listened' to many different relays before finalising this top-quality (cost no object) design, and more importantly (destructively) took apart any which were worthwhile using from the 'sonic' aspect, to inspect their internal constructions. This is important to ensure that they enjoy a long service life without any serious sonic detereoration, as I have discovered problems in this regard over the years.
Most relays have internal parts made of dissimilar metals, simply because some parts need to be springy, and others like contacts need to be hard and resistant to arcing, oxidation and wear etc.
Some contact detereoration happens over time even with the best totally-enclosed or inert-gass-filled relays, unfortunately, but this is not the only issue here.
I don't recommend using any relay for this purpose which has any internal parts riveted together, as this can give rise to later problems. All internal parts should ideally be spot-welded or friction-welded, so that there are no metal-to-metal junctions where any corrosion or other fouling can intervene *between* the parent metals.
It is said that whenever parts are securely clenched, crimped or riveted together, this will exclude all possibility of future corrosion as the air is excluded and the parts virtually weld themselves together.
However, this is another less well-appreciated 'theoretical oversight', as I have seen for myself when dissembling some of these relays. Perhaps the makers haven't taken the trouble which I have gone to in inspecting these parts after a period in service! Also, don't forget that many of these relays are originally designed for telecoms usage, but this application may not require the same overall bandwidths which we are interested in here, and in my experience it is important to maintain integrity to many times higher than our normal upper hearing threshold.
If you carefully separate the parts and inspect the junctions through which the signal needs to pass, there will frequently be some very obvious discolouration/oxidation or whatever, which is highly resistive, and non-linear in this regard. It cannot be seen until the parts are separated, and I believe this results from galvanic reactions, or something similar, when currents pass though dissimilar metal 'junctions', but whatever the reasons for this, the result is undesirable.
Incidentally, one Omron relay I tried was up with the best, and this was their High-Isolation G6A-BS series, with bifurcated (dual) contacts OK for use down to 10uA @10mV DC, and max. contact resistance of merely 50mOhm. These are rather noisy, only from the mechanical aspect, when they switch, resulting from the more positive switching and higher contact pressures used than in some other relays, but this is good for the audio sound, though. They are not suitable for high current applications.
Another quite good choice is the Panasonic DS Series.
Regards,
__________________
Bob
I would like to address two separate questions on relays.
First, for the JC-1 power amp, the output relay is OUTSIDE the feedback loop, so its output impedance is the series combination of the amp electronics AND the relay.
Second, while I use quality relays for switching inputs, etc., in the JC-2 preamp, there are NO relays in the BLOWTORCH, because we have found relays to be sonically slightly inferior to military grade silver switches.
This is one reason why a BLOWTORCH is NOT at the exact quality level as the JC-1 or the JC-1. It is slightly better, in fact.
First, for the JC-1 power amp, the output relay is OUTSIDE the feedback loop, so its output impedance is the series combination of the amp electronics AND the relay.
Second, while I use quality relays for switching inputs, etc., in the JC-2 preamp, there are NO relays in the BLOWTORCH, because we have found relays to be sonically slightly inferior to military grade silver switches.
This is one reason why a BLOWTORCH is NOT at the exact quality level as the JC-1 or the JC-1. It is slightly better, in fact.
john curl said:
I fully agree, and even the least-damaging (from the signal viewpoint) relays I have tried are not as transparent as my own Shallco (and Blore Edwards) silver-contact switched versions.
Commercially, they are much more convenient though, and nearly everyone nowadays seems to insist on remote operation of their audio equipment.
Yes, but remote operation can be still implemented with Shallco switches and stepper motors, not only for volume but also source selecting and phase switching. In a pictured unit, there are 4 sources, but six positions on a source selector: the outer ones are for reversed phase of first and last source. I kinda regret now that I didn't install motor on source selector as well, that would allow remote phase switching.
Attachments
Peter Daniel said:
Hi Peter,
Being similarly 'perfectionist' in your approaches to obtain the finest possible sonic results, I can only agree that using a motorised Shallco (or similar) will be the ultimate method here, and will end up with less 'damage' to the wanted delicate audio signals.
Sonically, I still prefer my own manual Shallco/naked Vishay attenuator over the commercial design mention above, but the design brief for that attenuator was for 64 discrete steps of precisely 1dB each, which is a bit difficult with Shallcos or Blore Edwards switches. AFAIK Shallco's maximum (single-switch) capability is 47 positions, and Blore Edwards is no more, regrettably, so the additional complication and expense for extra wafers or whatever was not attractive for this application.
I still use both at times, but getting-on in years I sometimes appreciate lately not needing to get up out of my easy chair to make any changes. 😉
Regards,
Well, gentlemen, we seem to be on the same 'page' with the difference between relays and quality switches. Yes, big silver switches are impractical, and not very handy to use, BUT they do make a good 'reference' don't they?
They most certainly do John, and when striving for the ultimate in highest-possible audio quality results, it is attention to every single detail like this which sets the men apart from the boys!
With some effort almost anyone can come up with an acceptable result with the technology and information available nowadays, but it takes a bit of experience to appreciate what really matters.😉
With some effort almost anyone can come up with an acceptable result with the technology and information available nowadays, but it takes a bit of experience to appreciate what really matters.😉
My AP System 1 is 24 years old and still meets it's -120dB residual distortion. yet, it has a whole slew of small-signal relays in for example the output config and impedance section. So, it seems possible to design your equipment in such a way that this is a non-issue.
Jan Didden
Jan Didden
Jan, it is NOT measured distortion that is the issue. It is 'loss' of information. IF you can show me where AP does anything different with relays than I do, for the same sort of function, please describe it. If not, you are barking up a tree. 
john curl said:Jan, it is NOT measured distortion that is the issue. It is 'loss' of information. IF you can show me where AP does anything different with relays than I do, for the same sort of function, please describe it. If not, you are barking up a tree.
Well, maybe that's my limitation. If you measure better than -120dB non-linearity after 24 years, I don't understand how there can still be 'loss of information', whatever that means . 😉
Jan Didden
What we need here is a good blind test that takes into account how we really hear sounds. Although, no would accept the results, since they only trust their beliefs. 
SY said:
Depends whose cable. https://edeskv2.belden.com/Products/techdata//english/swf/1316SB.swf
At 1.56 Ohms per conductor per 1000ft that makes .156 Ohms per 100ft of concustor, or 50 feet of Cable, so a 70 mOhm relay will be equivalent to about 25 feet of cable for this 12 AWG cable. Admittedly not 200 metres.
Their 14 AWG is shown as 2.42 Ohms per 1000ft.
The EAR knows, Jan, why fight it?
For the record, I have been professionally using miniature signal relays for the last 40 years.
Yes, 40 years ago Teledyne made a DPDT 1A relay in a TO-5 size transistor can.
I used them in projects for Ampex Research.
I also used them more than 26 years ago in the JC-80, using hermetically sealed units.
AND I use them in the latest JC-2 preamp, by the dozen.
NOW, where am I making a mistake? Have I overlooked something?
Please Jan, read Ragnar Holm's book cover to cover, then come back and we will discuss the merits and demerits of relay contacts in a useful way. I hope for more enlightenment.
For the record, I have been professionally using miniature signal relays for the last 40 years.
Yes, 40 years ago Teledyne made a DPDT 1A relay in a TO-5 size transistor can.
I used them in projects for Ampex Research.
I also used them more than 26 years ago in the JC-80, using hermetically sealed units.
AND I use them in the latest JC-2 preamp, by the dozen.
NOW, where am I making a mistake? Have I overlooked something?
Please Jan, read Ragnar Holm's book cover to cover, then come back and we will discuss the merits and demerits of relay contacts in a useful way. I hope for more enlightenment.
Re: dogs don't believe
Dogs do believe and so do cats.
🙄
What your point? You calling me dog?
albin said:
Dogs do believe and so do cats.
🙄
What your point? You calling me dog?
no
Never
Max
When I said we ,I mean't humanity,in general.
Please don't take offence.I find communication through a typewriter difficult
regards
Max
Never
Max
When I said we ,I mean't humanity,in general.
Please don't take offence.I find communication through a typewriter difficult
regards
Max
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