Do these really work or are they just "smoke and mirrors",
"snake-oil", "Area 51", "Sasquach", etc... ?

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762672005

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762670608

Thanks, -Barry

On Tue, 29 Mar 2005 07:40:26 +0000, Joe Schmo wrote:

Do these really work or are they just "smoke and mirrors", "snake-oil",
"Area 51", "Sasquach", etc... ?

If you're buying them at Pep Boys for 50 cents each as "3/4 inch
O-rings", a typical automotive part, it's not a bad investment.

--
Ned Carlson Triode Electronics Chicago,IL USA
www.triodeelectronics.com

On 29 Mar 2005 02:41:02 -0600, "Ned Carlson"
wrote:

On Tue, 29 Mar 2005 07:40:26 +0000, Joe Schmo wrote:

Do these really work or are they just "smoke and mirrors", "snake-oil",
"Area 51", "Sasquach", etc... ?

If you're buying them at Pep Boys for 50 cents each as "3/4 inch
O-rings", a typical automotive part, it's not a bad investment.

As opposed to the machined tungsten caps with tie-down springs I've
seen for $60/pair?
There may be some truth to it. After all, they do often glue down
electrolytic caps of size. But do dampers really help or exacerbate
the problem? They are confining the glass from moving but what does
this do to the filament, grid, etc?
-Rich

"Joe Schmo" wrote in message
...
Do these really work or are they just "smoke and mirrors",
"snake-oil", "Area 51", "Sasquach", etc... ?

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762672005

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762670608

Thanks, -Barry

As Ned said they are high-temp O-rings available from autoparts stores. As
to whether they work or not depends on a few things. If your tubes are very
microphonic you may find they help. Also if your amp is placed where there
are a lot of vibrations they can help.

I put them on an amp of mine and in normal listening I can't hear any
difference. However without the dampers if I tap a tube I can hear it quite
plainly in the speakers. With the dampers the sound from the speakers is
much less. However since I don't usually go around tapping the tubes while
playing the amp I doubt they make any difference.

Sherman

"Sherman" said:

I put them on an amp of mine and in normal listening I can't hear any
difference. However without the dampers if I tap a tube I can hear it quite
plainly in the speakers. With the dampers the sound from the speakers is
much less. However since I don't usually go around tapping the tubes while
playing the amp I doubt they make any difference.


Remember that about the only thing that can alter tube characteristics
is mechanical displacement of the internal parts.
Vibrations from e.g. a mains transformer or even high SPL may cause
this.

Of course, the tubes most succescible to such vibrations are low level
tubes in a phono stage or some such, and it's considered wisdom to
keep mains transformers well away from the amplifier itself.

When a tube is really microphonic, it's usually best to junk it.
Dampening rings are no real solution to microphony.

--
Sander de Waal
" SOA of a KT88? Sufficient. "

On Tue, 29 Mar 2005 07:40:26 GMT, Joe Schmo
wrote:

Do these really work or are they just "smoke and mirrors",
"snake-oil", "Area 51", "Sasquach", etc... ?

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762672005

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762670608

Thanks, -Barry

The problem is that the part that needs damping is not the envelope
but the electrode assembly, and you can't get at that with the tube
damper.

d

Pearce Consulting
http://www.pearce.uk.com

When a tube is really microphonic, it's usually best to junk it.
Dampening rings are no real solution to microphony.


Some tubes are commonly microphonic. Every 6AU6 I've tried in my Heathkit
has been. I don't personally mind it, kinda adds a smidge of echo. )

Don Pearce wrote...

The problem is that the part that needs damping is
not the envelope but the electrode assembly, and
you can't get at that with the tube damper.

But since the only way the internals can be excited
is via the envelope or the pins, changing the
vibration characteristics of the envelope may be
very helpful. Not in every case, of course, but
you can often get enough reduction to solve a
problem. And yes, in the spirit of full disclosure,
I do sell o-ring type dampers for $0.50 ea. or
12/$5.00 for 12AX7 diameter bottles, 6SN7
sized dampers are a bit more.

I use the o-rings at the point where the top mica
contacts the glass. And when I throw caution to
the winds I sometimes will put TWO dampers on
a tube, one at the lower mica as well as the top.

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!

On Tue, 29 Mar 2005 20:23:03 GMT, "Jim McShane"
wrote:

Don Pearce wrote...

The problem is that the part that needs damping is
not the envelope but the electrode assembly, and
you can't get at that with the tube damper.

But since the only way the internals can be excited
is via the envelope or the pins, changing the
vibration characteristics of the envelope may be
very helpful. Not in every case, of course, but
you can often get enough reduction to solve a
problem. And yes, in the spirit of full disclosure,
I do sell o-ring type dampers for $0.50 ea. or
12/$5.00 for 12AX7 diameter bottles, 6SN7
sized dampers are a bit more.

I use the o-rings at the point where the top mica
contacts the glass. And when I throw caution to
the winds I sometimes will put TWO dampers on
a tube, one at the lower mica as well as the top.

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!


OK - I'm interested in how they are supposed to work. You say they
should be fitted at the points where the mica bears against the glass.
What that is telling me is that they are actually preventing a flexing
mode within the glass, trying to place a node at the mounting points -
a very laudable thing to do. But compare the modulus of elasticity of
glass and silicone rubber, and tell me - just theoretically - how much
reduction in motion could be achieved this way.

The other - and rather more likely - way they can work is simply by
adding mass, and reducing the resonance frequency with the stiffness
of the pins. In that case all the mass should be placed as high as
possible on the valve.

Can you point me at the science please, because I just don't buy your
theory.

d

Pearce Consulting
http://www.pearce.uk.com

As already evidenced by many other Rodents, a high temperature O-ring is not
different from some more expensive "audio" stuff. By the way they're made
from a "stiff" rubber having sufficiently good damping characteristics
(natural rubber bounces so well that it wouldn't damp anything).
An external ring can only dampen GLASS vibration, and only if these
vibrations are in some way transferred to the ring and if the ring itself is
manufactured from a non-elastic material (ie, high elastic hysteresis)
because in order to dampen the vibration it needs to dissipate the relevant
mechanical energy as viscous attrition.
A reduction in glass vibration will reduce the amount of it passed to the
tube internal structure, thus reducing to some extent microphony (external
noise shall "pass through the glass" to reach the guts of the valve).
Briefly, dunking the tube in something like chewing gum would effectively
dampen it, but heat dissipation would get much worse. IMHO a SMALL silicon
ring (yes, the type used to seal bathtubs) around the base is mechanically
as good as any magic stuff. Make a thin sheet squeezing it on a cellophane
sheet, let it harden and cut the ring You need with scissors, then try it.
Placing it between the tube base and the amplifier chassis allows for more
vibration modes to be dampened (if it is placed half-way around the tube and
the vibration mode is "longer-shorter" ie along the axis, there's no
mechanical link between tube and dampening ring).
I have some experience with a couple of these "audio" rings (*) I use around
a couple of badly microphonic 9002 triodes I mistakenly placed as first gain
stage on my 30W PP 6L6GC amp. In fact, when tapping the tube with a pencil,
some damping effect can be observed when using this stuff, but since I don't
tap the tubes while I'm listening...
Now, over with engineering and back to audio: a 1$ home-made device can give
IMHO some improvement, but is usually not really relevant in "music" terms.
I remember that I saw some British McMurdo sockets for small signal tubes
where a rubber disc was placed between the mounting flange and the socket
itself: never tried 'em, but I suppose it's a much better solution if
there's really a vibration problem.

Ciao

Fabio


(*) don't ask me the name, I just remember I paid'em some 5-10$ some years
ago.



"Joe Schmo" ha scritto nel messaggio
...
Do these really work or are they just "smoke and mirrors",
"snake-oil", "Area 51", "Sasquach", etc... ?

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762672005

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762670608

Thanks, -Barry

"Don Pearce" wrote

OK - I'm interested in how they are supposed to
work. You say they should be fitted at the points
where the mica bears against the glass.

No, I said that's where I use them, there is no
specific location. I just find the best results there.
Purely empirical.

What that is telling me is that they are actually
preventing a flexing mode within the glass, trying
to place a node at the mounting points - a very
laudable thing to do. But compare the modulus
of elasticity of glass and silicone rubber, and tell
me - just theoretically - how much reduction in
motion could be achieved this way.

I can't, I'm not a physicist. I can only tell you from
personal (and many customer) experience that they
sometimes work very well.

Hey, maybe they cause a localized hot spot on the
glass and that changes something, I don't know.
I DO know that raising the heater voltage and
heating a badly microphonic tube above "normal"
will virtually always stop the microphonics. Of
course, that approach has many drawbacks...

The other - and rather more likely - way they
can work is simply by adding mass, and reducing
the resonance frequency with the stiffness of the
pins. In that case all the mass should be placed
as high as possible on the valve.

Okay.

Can you point me at the science please, because
I just don't buy your theory.

Come on, get off your high horse. I never said I was
scientist, I never made any claims as to why they
do what they do. I didn't say I invented them. I never
advanced ANY theory at all.

But I can tell you that I have heard a marked
improvement with my own ears in many cases. And
so have a number of people who got them from me.
As I also said before, not all cases, but a good
number. For 50 cents (or less in quantity) it's worth
a try if you ask me.

I can tell you that 3M developed a tube damper
some years back that was a thick flexible ring
around the tube, and it was quite effective. Maybe
they have some info on their site or something, I
don't know. There was also a respected audio
designer named Robert Modjeski (sp?) who
developed a line of o-ring dampers, maybe
there's some info there.

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!

On Tue, 29 Mar 2005 20:35:10 GMT, (Don Pearce)
wrote:

OK - I'm interested in how they are supposed to work. You say they
should be fitted at the points where the mica bears against the glass.
What that is telling me is that they are actually preventing a flexing
mode within the glass, trying to place a node at the mounting points -
a very laudable thing to do. But compare the modulus of elasticity of
glass and silicone rubber, and tell me - just theoretically - how much
reduction in motion could be achieved this way.

The other - and rather more likely - way they can work is simply by
adding mass, and reducing the resonance frequency with the stiffness
of the pins. In that case all the mass should be placed as high as
possible on the valve.

Can you point me at the science please, because I just don't buy your
theory.

Jim is an honest person and a believable observer, so, based on
his observations, I'd tend to go with your added mass theory.

Microphony is likely mostly variations in cathode-grid spacing,
and coupling from the outside world is likely mostly from the
outside world's air to the bottle. Anybody want to help with the
model? I don't trust myself lately.

The glass bottle itself is a fabulously high Q, implying lossless
transmission from the outside world inward at contact points.
Shake the bottle = shake the micas = shake the most rigid parts
(plates, etc.) and let the floppy grids waggle along behind.

FWIW, good acoustic decoupling would really include mechanically
isolating the bottle's socket, and connecting with flex-leads.

Very interesting topic, thanks,

Chris Hornbeck
6x9=42

If you're buying them at Pep Boys for 50 cents each as "3/4 inch
O-rings", a typical automotive part, it's not a bad investment.


Next time you need to replace the headlights in your car,
salvage the orange colored O ring off the old bulb's base.

On Tue, 29 Mar 2005 22:15:28 GMT, "Jim McShane"
wrote:

"Don Pearce" wrote

OK - I'm interested in how they are supposed to
work. You say they should be fitted at the points
where the mica bears against the glass.

No, I said that's where I use them, there is no
specific location. I just find the best results there.
Purely empirical.

You can hear the difference caused by moving these things around on
the valve? I'm duly impressed - and highly skeptical.

What that is telling me is that they are actually
preventing a flexing mode within the glass, trying
to place a node at the mounting points - a very
laudable thing to do. But compare the modulus
of elasticity of glass and silicone rubber, and tell
me - just theoretically - how much reduction in
motion could be achieved this way.

I can't, I'm not a physicist. I can only tell you from
personal (and many customer) experience that they
sometimes work very well.

Hey, maybe they cause a localized hot spot on the
glass and that changes something, I don't know.
I DO know that raising the heater voltage and
heating a badly microphonic tube above "normal"
will virtually always stop the microphonics. Of
course, that approach has many drawbacks...

Sounds more like a case for replacing a dodgy valve to me.

The other - and rather more likely - way they
can work is simply by adding mass, and reducing
the resonance frequency with the stiffness of the
pins. In that case all the mass should be placed
as high as possible on the valve.

Okay.

Can you point me at the science please, because
I just don't buy your theory.

Come on, get off your high horse. I never said I was
scientist, I never made any claims as to why they
do what they do. I didn't say I invented them. I never
advanced ANY theory at all.

But I can tell you that I have heard a marked
improvement with my own ears in many cases. And
so have a number of people who got them from me.
As I also said before, not all cases, but a good
number. For 50 cents (or less in quantity) it's worth
a try if you ask me.

I can tell you that 3M developed a tube damper
some years back that was a thick flexible ring
around the tube, and it was quite effective. Maybe
they have some info on their site or something, I
don't know. There was also a respected audio
designer named Robert Modjeski (sp?) who
developed a line of o-ring dampers, maybe
there's some info there.

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!


Time to take a step forwards to a non-microphonic technology,
methinks...

d

Pearce Consulting
http://www.pearce.uk.com

Sherman wrote:

However since I don't usually go around tapping the tubes while
playing the amp I doubt they make any difference.

You only do this to find out where "bad vibes" couple into your
audio equipment, do you? If you´re listening to vinyls - very
likely with tube amp enthusiasts - you may want to tap the vinyl
itself, stylus down but turntable not rotating...

It is a very good idea to have the vinyl dampened (sought to the
turntable e. g. by some vacuum) - the difference is truely amazing.
It is "microphonic" like nothing else in the reproduction chain.

Cheers

Walther

Don Pearce wrote...

You can hear the difference caused by moving these
things around on the valve? I'm duly impressed -
and highly skeptical.

Stop putting words in my mouth! That's not what I said,
I said I get the best results from that location.

Sounds more like a case for replacing a dodgy valve
to me.

Well maybe, but do you really want to toss out a
rare item that could be saved?

Time to take a step forwards to a non-microphonic
technology, methinks...

Time to open your mind a bit, methinks...

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!

On Wed, 30 Mar 2005 19:34:56 GMT, "Jim McShane"
wrote:

Don Pearce wrote...

You can hear the difference caused by moving these
things around on the valve? I'm duly impressed -
and highly skeptical.

Stop putting words in my mouth! That's not what I said,
I said I get the best results from that location.

So the best results *aren't* the best sound? You need to explain your
definition of "best results" for me, I'm afraid.

Sounds more like a case for replacing a dodgy valve
to me.

Well maybe, but do you really want to toss out a
rare item that could be saved?

Certainly.

Time to take a step forwards to a non-microphonic
technology, methinks...

Time to open your mind a bit, methinks...


I already have. You should try it yourself.

d

Pearce Consulting
http://www.pearce.uk.com

Don Pearce wrote...

So the best results *aren't* the best sound? You need
to explain your definition of "best results" for me, I'm
afraid.

Most likely to eliminate excessive microphonic tendencies.

I already have. You should try it yourself.

You need to explain your definition of "open mind" for me,
I'm afraid. You've got a mind like a steel trap - rusted
shut.

This is my last post on this. Serves me right for even
bothering
with RAT anymore.

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!

they are mostly smoke, but occasionally help

if you have microphonics on an expensive tube, almost anything is worth a
try, to not have to trash a $150 tube, but the miracles are not very
frequent, so don't get your hopes too high

but then again, you could be a lucky case


"Joe Schmo" wrote in message
...
Do these really work or are they just "smoke and mirrors",
"snake-oil", "Area 51", "Sasquach", etc... ?

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762672005

http://cgi.ebay.com/ws/eBayISAPI.dll...category=64629
&item=5762670608

Thanks, -Barry

This is my last post on this. Serves me right for even
bothering
with RAT anymore.

Jim McShane


you'll be missed!

On Wed, 30 Mar 2005 21:46:30 GMT, "Jim McShane"
wrote:

Don Pearce wrote...

So the best results *aren't* the best sound? You need
to explain your definition of "best results" for me, I'm
afraid.

Most likely to eliminate excessive microphonic tendencies.

I already have. You should try it yourself.

You need to explain your definition of "open mind" for me,
I'm afraid. You've got a mind like a steel trap - rusted
shut.

This is my last post on this. Serves me right for even
bothering
with RAT anymore.

You don't like what I say so you are going away? Now *that's* what I
call an open mind!

d

Pearce Consulting
http://www.pearce.uk.com

On Tue, 29 Mar 2005 20:35:10 +0000, Don Pearce wrote:
The other - and rather more likely - way they can work is simply by adding
mass, and reducing the resonance frequency with the stiffness of the pins.
In that case all the mass should be placed as high as possible on the
valve.

Can you point me at the science please, because I just don't buy your
theory.

I can't point you to any science, but I can point you
to an anecdotal example: high gain AM radio detector tubes
from the 1920's often had heavy lead covers on them, to dampen
microphonics.

You yourself posted:
Time to take a step forwards to a non-microphonic technology, methinks...

IOW, you're prejudiced against a technology that DirecTV uses
in its satellite transponders,and the US military considers it
one of its "Top Ten Most Critical". Naval Research Laboratories
research on tubes is so secret that trying to look it up gets
a "password required" prompt if you try to delve deeper.

Ever see a Phalanx system knock off a naval anti-ship missle?
Thank tubes, transistors can't do it.

--
Ned Carlson Triode Electronics Chicago,IL USA
www.triodeelectronics.com

On 31 Mar 2005 02:52:03 -0600, "Ned Carlson"
wrote:

On Tue, 29 Mar 2005 20:35:10 +0000, Don Pearce wrote:
The other - and rather more likely - way they can work is simply by adding
mass, and reducing the resonance frequency with the stiffness of the pins.
In that case all the mass should be placed as high as possible on the
valve.

Can you point me at the science please, because I just don't buy your
theory.

I can't point you to any science, but I can point you
to an anecdotal example: high gain AM radio detector tubes
from the 1920's often had heavy lead covers on them, to dampen
microphonics.



As for the heavy lead covers - they confirm my point exactly. What
they do is add mass, reducing the resonance frequency with the
stiffness of the pins. I wish you would actually read what I write
instead of simply lashing out.

You yourself posted:
Time to take a step forwards to a non-microphonic technology, methinks...

IOW, you're prejudiced against a technology that DirecTV uses
in its satellite transponders,and the US military considers it
one of its "Top Ten Most Critical". Naval Research Laboratories
research on tubes is so secret that trying to look it up gets
a "password required" prompt if you try to delve deeper.

Absolutely. I learned my electronics on valves, and as recently as ten
years ago I was designing satellite transponders with travelling wave
tubes. Valve-based technology has the unique advantage of being
intrinsically immune to the effects of cosmic ray bombardment, and of
course there isn't much in space that is going to trouble a
microphonic component.

And the design of a tea cup is still top secret - that is the default
status for everything in the military unless anybody decides
otherwise.

Ever see a Phalanx system knock off a naval anti-ship missle?
Thank tubes, transistors can't do it.

I saw plenty of Patriot missile failing to knock down a single Scud
missile during the Gulf war - does that count?

d

Pearce Consulting
http://www.pearce.uk.com

I saw plenty of Patriot missile failing to knock down a single Scud
missile during the Gulf war - does that count?

d

Pearce Consulting

ummmm, don't blame tubes, the patriot missile system had buggy software, the
hardware worked flawlessly, it was just given bad targeting data from the
buggy software (now fixed)

this is why nepotism is a bad thing, firms should get contracts based on
WHAT they know, rather than WHO they know!

Don Pearce wrote...

You don't like what I say so you are going away?
Now *that's* what I call an open mind!

Classic definition of insanity - do the same things
repeatedly, and expect different results.

I (and others) have repeatedly related personal
experiences showing tube damping can sometimes
be effective. You repeatedly ignore the anecdotal
evidence, the experiences.

It would seem you don't want a discussion, you
want either validation, or to show off how smart
you are.

I'm not insane (nor is Ned BTW).

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!

On Thu, 31 Mar 2005 23:29:32 GMT, "Jim McShane"
wrote:

Don Pearce wrote...

You don't like what I say so you are going away?
Now *that's* what I call an open mind!

Classic definition of insanity - do the same things
repeatedly, and expect different results.

I (and others) have repeatedly related personal
experiences showing tube damping can sometimes
be effective. You repeatedly ignore the anecdotal
evidence, the experiences.


You seem to have forgotten what I wrote. I not only believe, but I
know that adding mass to valves has beneficial effects on microphony.
What I was questioning was your interpretation of what was happening.
Like so many tubies, you appear unable to accept the simple truth, but
need to imbue it with ritual and mythology. Hence moving the masses on
the tubes to their astrologically derived "correct" positions makes
some sort of difference - but you insist that this is nothing to do
with best sound (you still haven't explained that).

Now listen hard. You are NOT damping the mica mounts internally by
positioning the rings over them outside the glass. Adding more mass is
what makes things better - and it is not by changing the damping, but
by lowering the resonance frequency and consequently lowering the
turnover point of the mechanical lowpass filter comprising the pins
and the mass.

It would seem you don't want a discussion, you
want either validation, or to show off how smart
you are.


I'm very happy to have a discussion, but I can't if you are simply
going to ram your fingers in your ears and go "LA LA LA" when I say
something that doesn't fit your agenda.

I'm not insane (nor is Ned BTW).


I'm happy to hear that.

d

Pearce Consulting
http://www.pearce.uk.com

Don Pearce wrote...

You seem to have forgotten what I wrote.

Believe me, I'm trying to.

Like so many tubies, you appear unable to accept
the simple truth, but need to imbue it with ritual and
mythology.

What the hell are you talking about?

Hence moving the masses on the tubes to their
astrologically derived "correct" positions makes
some sort of difference - but you insist that this
is nothing to do with best sound (you still haven't
explained that).

Look pal, all I ever wrote was that sometimes
in my experience damper rings sometimes reduces
microphonics. I never made any scientific claims
of any kind. Are you delusional or something?

Now listen hard. You are NOT damping the mica
mounts internally by positioning the rings over them
outside the glass. Adding more mass is what makes
things better - and it is not by changing the damping,
but by lowering the resonance frequency and
consequently lowering the turnover point of the
mechanical lowpass filter comprising the pins
and the mass.

I NEVER SAID ANYTHING ABOUT ANY
SCIENTIFIC EXPLANATION. NOTHING,
NADA, NIL, ZILCH, ZERO, NULL. LET ME
QUOTE MY POSTS ABOUT THE SCIENCE
AND WHY/HOW THEY WORK :

"I can't, I'm not a physicist. I can only tell you from
personal (and many customer) experience that they
sometimes work very well."

OR THIS:

"I never said I was a scientist, I never made any claims
as to why they do what they do. I didn't say I invented
them. I never advanced ANY theory at all.

I'm very happy to have a discussion, but I can't if
you are simply going to ram your fingers in your
ears and go "LA LA LA" when I say something
that doesn't fit your agenda.

I'm sorry, but you're just plain nuts. You're just engaged
in self-flagellation.

Jim McShane
Need Tubes? Got a H-K Citation (Pre) Amp?
Check http://pages.prodigy.net/jimmcshane
Repro knobs for Citation gear in stock!

Don't be a dick; we already have too many.

Chris Hornbeck
6x9=42

in article , Chris Hornbeck at
wrote on 4/1/05 7:12 PM:

Don't be a dick; we already have too many.

Chris Hornbeck
6x9=42


Who licked the red off of your candy??

On Fri, 01 Apr 2005 20:44:07 -0500, Jon Yaeger
wrote:

Who licked the red off of your candy??

Arf!

I have the greatest respect for Mr. Pearce. And I have ongoing
worries about the health of the newsgroup. Should I just shut
up (certainly no great loss to the group) or should I voice
an honest opinion to a respected peer?

Guys, it's just a hobby; enjoy.

Chris Hornbeck
6x9=42

(Don Pearce) wrote in news:424d0032.48562140
@news.plus.net:


Now listen hard. You are NOT damping the mica mounts internally by
positioning the rings over them outside the glass. Adding more mass is
what makes things better - and it is not by changing the damping, but
by lowering the resonance frequency and consequently lowering the
turnover point of the mechanical lowpass filter comprising the pins
and the mass.


Pearl Coolers count as mass? Because on the 6dj8's in my phono pre they
made an obvious difference in the microphonics susceptibility. And not the
voodoo type, the "rang for seconds, now a dull thud when tapping the
chassis" type difference. And yes, seconds, because of some stupid design
decsion the manufacturer made regarding chassis and heat sink choices
(transistor regulation.)
Massy enough?

On Fri, 01 Apr 2005 23:06:56 GMT, "Jim McShane"
wrote:

Don Pearce wrote...

You seem to have forgotten what I wrote.

Believe me, I'm trying to.

That would be your "open mind" at work again, Jim?

Enjoy your delusions.

d

Pearce Consulting
http://www.pearce.uk.com

Fabio Berutti wrote:
I remember that I saw some British McMurdo sockets for small signal tubes
where a rubber disc was placed between the mounting flange and the socket
itself: never tried 'em, but I suppose it's a much better solution if
there's really a vibration problem.

PEARL made an 'iso-socket' similar to your description with a sorbothane
layer between the socket and the chassis. Thin flexible wires connected
to the pins and a loose center bolt kept the contraption in place when
interting and removing tubes. It wasn't easy to install, but I used
for an application with microphonic 6DJ8's and it worked pretty well.

I've had better success damping and/or isolating the chassis rather than the glass
tube envelope.

On Sat, 02 Apr 2005 05:01:01 GMT, "my_name_here"
wrote:

(Don Pearce) wrote in news:424d0032.48562140
:


Now listen hard. You are NOT damping the mica mounts internally by
positioning the rings over them outside the glass. Adding more mass is
what makes things better - and it is not by changing the damping, but
by lowering the resonance frequency and consequently lowering the
turnover point of the mechanical lowpass filter comprising the pins
and the mass.


Pearl Coolers count as mass? Because on the 6dj8's in my phono pre they
made an obvious difference in the microphonics susceptibility. And not the
voodoo type, the "rang for seconds, now a dull thud when tapping the
chassis" type difference. And yes, seconds, because of some stupid design
decsion the manufacturer made regarding chassis and heat sink choices
(transistor regulation.)
Massy enough?

So what exactly was microphonic? You seem to be saying it was
something to do with the chassis and heat sink, not the tubes
themselves. An odd individual case like this would need to be treated
on its merits and you seem to have found a solution. Did you go back
to the manufacturer and ask them to fix it first?

d

Pearce Consulting
http://www.pearce.uk.com

"Chris Hornbeck" wrote in message
...
: On Fri, 01 Apr 2005 20:44:07 -0500, Jon Yaeger
: wrote:
:
: Who licked the red off of your candy??
:
: Arf!
:
: I have the greatest respect for Mr. Pearce. And I have ongoing
: worries about the health of the newsgroup. Should I just shut
: up (certainly no great loss to the group) or should I voice
: an honest opinion to a respected peer?
:
: Guys, it's just a hobby; enjoy.

Well, yes. But different people take a different take on how they like
to pursue that hobby. Ranging from trial-and-error development to
modeling, applying first principles and _then_ measuring, remodeling
Room for all types, no ?

Rudy

: Chris Hornbeck
: 6x9=42

(Don Pearce) wrote in
:

So what exactly was microphonic? You seem to be saying it was
something to do with the chassis and heat sink, not the tubes
themselves. An odd individual case like this would need to be treated
on its merits and you seem to have found a solution. Did you go back
to the manufacturer and ask them to fix it first?


It was the tube being excited by a chassis divider (poorly fixtured)
resonance and SS heat sinks mounted on the board. Without altering the
latter two the 'ping' from tapping the PCB was greatly reduced by slipping
on a pair of Pearl Coolers. Correcting the causes of the excitation with
some quick and dirty hacks obviously worked to further reduce the
susceptibility but the Pearls alone did an obvious and impressive job on
their own. To be clear, by obvious I don't mean "easier to hear the brand
of varnish on the violin in the second row", I mean much less output from
tapping the PCB.
Yes, the current iteration of the original manufacturer was willing to
perform these same quick and dirty hacks for $85/hour plus parts and
shipping.

Ned Carlson wrote:

On Tue, 29 Mar 2005 20:35:10 +0000, Don Pearce wrote:
The other - and rather more likely - way they can work is simply by adding
mass, and reducing the resonance frequency with the stiffness of the pins.
In that case all the mass should be placed as high as possible on the
valve.

Can you point me at the science please, because I just don't buy your
theory.

I can't point you to any science, but I can point you
to an anecdotal example: high gain AM radio detector tubes
from the 1920's often had heavy lead covers on them, to dampen
microphonics.

I can sure verify that. One of the amps I built for publication, "The 33 Power
Amp", used a 1B5/25S at the front end. It was almost like having a mike on the
chassis. Otherwise, an OK amp & interesting project to see what one could do
with 2 volt battery type tubes.

You yourself posted:
Time to take a step forwards to a non-microphonic technology, methinks...

IOW, you're prejudiced against a technology that DirecTV uses
in its satellite transponders,and the US military considers it
one of its "Top Ten Most Critical". Naval Research Laboratories
research on tubes is so secret that trying to look it up gets
a "password required" prompt if you try to delve deeper.

Ever see a Phalanx system knock off a naval anti-ship missle?
Thank tubes, transistors can't do it.

--
Ned Carlson Triode Electronics Chicago,IL USA
www.triodeelectronics.com

There sure has been lots of talk & a little BS reference this microphonics buz.
About 11 years ago I visited Bill Perkins of PEARL in Calgary. I got a copy of
his reprint of an earlier study on that very subject. For anyone interested,
I've posted it at ABSE. The file contains 2.5 pages of text & graphical results,
a little more than one meg.

I've tried to contact Bill again recently, but no luck. Anyone know what
happened to him?

Cheers, John Stewart

John Stewart wrote:
snip

There sure has been lots of talk & a little BS reference this microphonics buz.
About 11 years ago I visited Bill Perkins of PEARL in Calgary. I got a copy of
his reprint of an earlier study on that very subject. For anyone interested,
I've posted it at ABSE. The file contains 2.5 pages of text & graphical results,
a little more than one meg.

I've tried to contact Bill again recently, but no luck. Anyone know what
happened to him?

Cheers, John Stewart


Bill's at AMcom. Remove the obvious.

Raymond

Raymond Koonce wrote:

John Stewart wrote:
snip

There sure has been lots of talk & a little BS reference this microphonics buz.
About 11 years ago I visited Bill Perkins of PEARL in Calgary. I got a copy of
his reprint of an earlier study on that very subject. For anyone interested,
I've posted it at ABSE. The file contains 2.5 pages of text & graphical results,
a little more than one meg.

I've tried to contact Bill again recently, but no luck. Anyone know what
happened to him?

Cheers, John Stewart


Bill's at AMcom. Remove the obvious.

Raymond

Thanx Ray. I will chase that down. John Stewart