[Esmond Pitt[_2_]]

On 26/03/2011 3:24 PM, Audio Empire wrote:
The hardest part was replacing the
multi-section electrolytic capacitor in the power supply (these are no longer
available)

I fitted two brand-new multi-section electrolytic capacitors into a
vintage valve amplifier just a few weeks ago. They are still produced in
reasonable variety for the guitar amplifier market.

[Audio Empire]

On Sat, 2 Apr 2011 17:49:24 -0700, Esmond Pitt wrote
(in article ):

On 26/03/2011 3:24 PM, Audio Empire wrote:
The hardest part was replacing the
multi-section electrolytic capacitor in the power supply (these are no
longer
available)

I fitted two brand-new multi-section electrolytic capacitors into a
vintage valve amplifier just a few weeks ago. They are still produced in
reasonable variety for the guitar amplifier market.

Hmmm. I've tried to restore a number of pieces of vintage gear, including a
Citation One preamp. I was told by everybody that these multi-section caps
aren't available any more. Do you have a source?

[Esmond Pitt[_2_]]

On 4/04/2011 2:54 AM, Audio Empire wrote:
Do you have a source?

http://www.tubesandmore.com/

[Peter Wieck]

On Apr 3, 12:54=A0pm, Audio Empire wrote:

Hmmm. I've tried to restore a number of pieces of vintage gear, including=
a
Citation One preamp. I was told by everybody that these multi-section cap=
s
aren't available any more. Do you have a source?

https://www.tubeworld.com/metcaps.htm

http://www.radiodaze.com/capsMS.htm

http://www.dynakitparts.com/store/product.aspx?id=3D273

http://www.vibroworld.com/parts/tech15.html

However, it is better, cheaper and more precise to simply re-stuff the
existing can with new capacitors terminating through the phenolic
wafer base. It takes a bit of skill and your wife's hair-dryer to
release the old innards (well, more practice than skill), but once you
have done it a few times it becomes quite simple. The most difficult
part of the process is de-soldering and releasing the old can from the
chassis without breaking off the twist-tabs. Modern capacitors are
tiny as compared to older types and so this is entirely practical.

Better: Single-value capacitors may be screened individually for
whatever parameters apply. A typical electrolytic may be -20%/+100%
and still meet 'tolerance'. Too much capacitance may mean a higher B+,
especially mixed with higher wall-plate voltages these days -
something to be considered. Better also as one may use a higher
voltage with little or no cost penalty - Dynaco as one very typical
example drove its power-supply filter caps at very, very near their
rated voltage. Mix that with wallplate voltages often in excess of
120V, and that can be a bad combination.

Cheaper: Individual capacitors made as-such are remarkably cheaper per
uF than sectional caps. And, you already have the can and know that it
will fit just fine. \

More precise - closely matched values, higher voltages, and the
ability to add small-value film caps internally across the individual
cap leads.

I stopped looking for sectionals 20 years ago - and haven't lost a
patient yet. Nor would I trust any NOS unit as (electrolytic)
capacitors age whether they are in use or not - in fact, they age more
from disuse than from use. Reforming is *possible*, but something I do
only with the full understanding that eventual failure is just that -
eventual. Will, not May, and When, not If.

Peter Wieck
Melrose Park, PA

[Arny Krueger]

"Audio Empire" wrote in message


On Sat, 2 Apr 2011 17:49:24 -0700, Esmond Pitt wrote
(in article
):


I fitted two brand-new multi-section electrolytic
capacitors into a vintage valve amplifier just a few
weeks ago. They are still produced in reasonable variety
for the guitar amplifier market.

Hmmm. I've tried to restore a number of pieces of vintage
gear, including a Citation One preamp. I was told by
everybody that these multi-section caps aren't available
any more. Do you have a source?

As a rule people gut the old capacitor case and conceal a collection of
modern capacitors inside of it. Capacitors have shrunk enough that this is
generally very easy to do, and results in an equal-or-better end product.
For example one of my friends did this with a pair of MacIntosh 75 watt
tubed amps.

[Audio Empire]

On Mon, 4 Apr 2011 05:54:08 -0700, Arny Krueger wrote
(in article ):

"Audio Empire" wrote in message


On Sat, 2 Apr 2011 17:49:24 -0700, Esmond Pitt wrote
(in article
):


I fitted two brand-new multi-section electrolytic
capacitors into a vintage valve amplifier just a few
weeks ago. They are still produced in reasonable variety
for the guitar amplifier market.

Hmmm. I've tried to restore a number of pieces of vintage
gear, including a Citation One preamp. I was told by
everybody that these multi-section caps aren't available
any more. Do you have a source?

As a rule people gut the old capacitor case and conceal a collection of
modern capacitors inside of it. Capacitors have shrunk enough that this is
generally very easy to do, and results in an equal-or-better end product.
For example one of my friends did this with a pair of MacIntosh 75 watt
tubed amps.



Yes, that was certainly an alternative. Since the Citation had ample space
under the chassis, I merely replaced the multi-section cap with modern caps
wired under the chassis. I left the old multi-section cap on the chassis but
completely disconnected, however, to maintain an authentic look.

[Peter Wieck]

On Apr 4, 3:22=A0pm, Audio Empire wrote:
On Mon, 4 Apr 2011 05:54:08 -0700, Arny Krueger wrote
(in article ):





"Audio Empire" wrote in message


On Sat, 2 Apr 2011 17:49:24 -0700, Esmond Pitt wrote
(in article
):

I fitted two brand-new multi-section electrolytic
capacitors into a vintage valve amplifier just a few
weeks ago. They are still produced in reasonable variety
for the guitar amplifier market.

Hmmm. I've tried to restore a number of pieces of vintage
gear, including a Citation One preamp. I was told by
everybody that these multi-section caps aren't available
any more. Do you have a source?

As a rule people gut the old capacitor case and conceal a collection of
modern capacitors inside of it. Capacitors have shrunk enough that this=
is
generally very easy to do, and results in an equal-or-better end produc=
t.

[Audio Empire]

On Tue, 5 Apr 2011 01:36:10 -0700, Peter Wieck wrote
(in article ):

On Apr 4, 3:22=A0pm, Audio Empire wrote:
On Mon, 4 Apr 2011 05:54:08 -0700, Arny Krueger wrote
(in article ):





"Audio Empire" wrote in message


On Sat, 2 Apr 2011 17:49:24 -0700, Esmond Pitt wrote
(in article
):

I fitted two brand-new multi-section electrolytic
capacitors into a vintage valve amplifier just a few
weeks ago. They are still produced in reasonable variety
for the guitar amplifier market.

Hmmm. I've tried to restore a number of pieces of vintage
gear, including a Citation One preamp. I was told by
everybody that these multi-section caps aren't available
any more. Do you have a source?

As a rule people gut the old capacitor case and conceal a collection of
modern capacitors inside of it. Capacitors have shrunk enough that this=
is
generally very easy to do, and results in an equal-or-better end produc=
t.
For example one of my friends did this with a pair of MacIntosh 75 watt
tubed amps.

Yes, that was certainly an alternative. Since the Citation had ample spac=
e
under the chassis, I merely replaced the multi-section cap with modern ca=
ps
wired under the chassis. I left the old multi-section cap on the chassis =
but
completely disconnected, however, to maintain an authentic look.- Hide qu=
ote d text -

- Show quoted text -

Have a care putting caps willy-nilly under the chassis. In more than a
few cases you risk rF interference installing caps with unshielded
leads, and/or hum loops for the same reason. Those of us who make a
habit of restoring highly sensitive multi-band tube radios are well
acquainted with this issue - and there is quite a bit of cross-
fertilization between these two branches of the hobby. Caps are kept
in cans and above the chassis for a reason more than just good looks.

Further to this, if you were an afficionado of vintage equipment and
followed some of the original US-made AR electronics and the
literature around it, you would have come across articles written by
their designers on how the early iterations of their amps were
sensitive to citizens' band radio inteference due to the electrolytic
reaction of their rivet plating and their chassis plating - and the
phono-ground to the chassis through the rivet. No kidding. I have a
perhaps-over complimentary feeling towards AR - they really did let it
all hang out with their customers. I remember a 3-page apology I got
from their service department (in 1975) when I had sent them one of
their amps for the second time for the same problem. Chapter and verse
how the original design flaw was discovered, corrected and how they
missed it on mine. Felix Bartholdi signed that note. And over the next
many years until they folded altogether we spoke on a regular basis -
just keeping up. To the point that in 2008, when I needed very
specific parts to restore an AR amp, he connected me to the original
designer - by conference call - who sent me a half-dozen special-
purchase transistors from his private stash, gratis.

Yes, old is quite often much better than new.... as are the people
behind it.

Peter Wieck
Melrose Park, PA


Interesting anecdote. Thanks.

Well, the Citation I that I restored was my only foray into that end of the
hobby. I found this preamp at an electronics flea market, complete with wood
case. Since I had lusted after one in high school (Stewart Hegeman had always
been one of my audio design heros), I bought the thing for peanuts. Upon
getting it home, I found the switches and pots to be noisy, the background
hiss was higher than I would accept, and it had a slight hum that became an
annoying hum on phono. So I decided to rebuild it. I found a schematic and a
parts list on-line, and bought all modern parts: metal-film resistors,
polypropylene, polystyrene, and mylar capacitors for the signal path, and
modern electrolytic caps for the power supply. When it was finished (a
daunting task, as this thing was NOT simple like the Dyna PAS-3), it was
quiet, didn't hum, and sounded excellent. The only problem with it was that
the RCA I/O jacks were the old-fashioned tin-plated ones with the ceramic
insulator doughnuts in them and they were in closely spaced pairs, riveted to
the top of the chassis (pointing toward the ceiling rather than perpendicular
to the back apron). These were made in the days when the only available
interconnects were those one made oneself. There was absolutely NO clearance
between each input for two moulded cables with strain reliefs side-by-side.
So the thing sat around for a couple of years while I sort of half-heartedly
looked for a practical way to replace the jack field on the back with some
modern single-hole mounting gold plated connectors (such as those sold by WBT
et al). I had toyed with the notion of cutting the top of the chassis out and
replacing it with another piece of steel, but I realized that even with both
halves of the rear jack field replaced (one on the left side of the chassis
and one on the right side), there would not be room for all of the I/O jacks
(at a sufficient clearance to allow for modern strain-relieved cables) needed
for the unit. I finally sold it for a fraction of the $400 or so that I had
sunk into it.

I do not routinely restore vintage gear, although I can see where it could be
a rewarding hobby for those so inclined. I did it once and that was enough
(ditto for restoring cars. I did it once - a 1986 Alfa Romeo GTV-6, no need
to go through that again).

[Andrew Haley]

Arny Krueger wrote:
"Audio Empire" wrote in message


Hmmm. I've tried to restore a number of pieces of vintage
gear, including a Citation One preamp. I was told by
everybody that these multi-section caps aren't available
any more. Do you have a source?

As a rule people gut the old capacitor case and conceal a collection
of modern capacitors inside of it. Capacitors have shrunk enough
that this is generally very easy to do, and results in an
equal-or-better end product. For example one of my friends did this
with a pair of MacIntosh 75 watt tubed amps.

I'm finding this quite baffling. What is the point of replacing a
multi-section cap with another one? Can't you just put a single-
section cap in its place, or is the problem that the values/ voltages
aren't available?

Andrew.

[Arny Krueger]

"Andrew Haley" wrote in
message
Arny Krueger wrote:
"Audio Empire" wrote in
message

Hmmm. I've tried to restore a number of pieces of
vintage gear, including a Citation One preamp. I was
told by everybody that these multi-section caps aren't
available any more. Do you have a source?

As a rule people gut the old capacitor case and conceal
a collection of modern capacitors inside of it.
Capacitors have shrunk enough that this is generally
very easy to do, and results in an equal-or-better end
product. For example one of my friends did this with a
pair of MacIntosh 75 watt tubed amps.

I'm finding this quite baffling. What is the point of
replacing a multi-section cap with another one? Can't
you just put a single- section cap in its place, or is
the problem that the values/ voltages aren't available?

The sections of multi-section capacitors are not usually hooked together
directly. For example one section might be hooked to the cathode of the
rectifier tube, the second to the output of a filter choke, and the third to
a resistor that is part of a decoupling network for a phono preamp.

[Audio Empire]

On Tue, 5 Apr 2011 05:30:29 -0700, Arny Krueger wrote
(in article ):

"Andrew Haley" wrote in
message
Arny Krueger wrote:
"Audio Empire" wrote in
message

Hmmm. I've tried to restore a number of pieces of
vintage gear, including a Citation One preamp. I was
told by everybody that these multi-section caps aren't
available any more. Do you have a source?

As a rule people gut the old capacitor case and conceal
a collection of modern capacitors inside of it.
Capacitors have shrunk enough that this is generally
very easy to do, and results in an equal-or-better end
product. For example one of my friends did this with a
pair of MacIntosh 75 watt tubed amps.

I'm finding this quite baffling. What is the point of
replacing a multi-section cap with another one? Can't
you just put a single- section cap in its place, or is
the problem that the values/ voltages aren't available?

The sections of multi-section capacitors are not usually hooked together
directly. For example one section might be hooked to the cathode of the
rectifier tube, the second to the output of a filter choke, and the third to
a resistor that is part of a decoupling network for a phono preamp.



Or it might constitute both capacitors in a "pi" network power supply filter
with a choke or resistor between the two sections.

[Arny Krueger]

"Audio Empire" wrote in message

On Tue, 5 Apr 2011 05:30:29 -0700, Arny Krueger wrote
(in article ):

"Andrew Haley" wrote
in
message
Arny Krueger wrote:
"Audio Empire" wrote in
message

Hmmm. I've tried to restore a number of pieces of
vintage gear, including a Citation One preamp. I was
told by everybody that these multi-section caps aren't
available any more. Do you have a source?

As a rule people gut the old capacitor case and conceal
a collection of modern capacitors inside of it.
Capacitors have shrunk enough that this is generally
very easy to do, and results in an equal-or-better end
product. For example one of my friends did this with a
pair of MacIntosh 75 watt tubed amps.

I'm finding this quite baffling. What is the point of
replacing a multi-section cap with another one? Can't
you just put a single- section cap in its place, or is
the problem that the values/ voltages aren't available?

The sections of multi-section capacitors are not usually
hooked together directly. For example one section might
be hooked to the cathode of the rectifier tube, the
second to the output of a filter choke, and the third to
a resistor that is part of a decoupling network for a
phono preamp.

Or it might constitute both capacitors in a "pi" network
power supply filter with a choke or resistor between the
two sections.

Note that this is what you have if "...one section (is)
hooked to the cathode of the rectifier tube..." and "....he
second to the output of a filter choke...", per my post above.