[Bret L]

In going back and reading through some of the books I have and
recommend it's astonishing now how the audio world had pretty much
everything it needed by 1955. After that, it's just detail
improvement, or in some cases deprovement.

They didn't have cheap silicon diodes, so you needed tube rectifiers,
not only for HV but bias as well unless you wanted to use a battery.
And a relay to open if no bias voltage was there and bring in a
cathode resistor. Also, low impedance B+ supplies were tougher, but Hg
vapor or xenon tubes were available that worked well.

Are we better off today? Well, yes, in all objective measures. But it
isn't as much fun is it? And in a lot of ways we aren't that much
better off. A lot of audio equipment still sells for stupid sums.

[John Stone]

On 7/14/10 8:37 PM, in article
, "Bret L"
wrote:

They didn't have cheap silicon diodes, so you needed tube rectifiers,
not only for HV but bias as well unless you wanted to use a battery.
And a relay to open if no bias voltage was there and bring in a
cathode resistor.


Um, ever hear of a selenium rectifier? Mac, early Marantz, Fisher, Dynaco,
etc all had 'em for bias and dc heater applications. Yeah, they wore out
after 10 years or so, but by then you had the silicon replacements.

[Bret L]

On Jul 14, 8:45*pm, John Stone wrote:
On 7/14/10 8:37 PM, in article
, "Bret L"

wrote:
*They didn't have cheap silicon diodes, so you needed tube rectifiers,
not only for HV but bias as well unless you wanted to use a battery.
And a relay to open if no bias voltage was there and bring in a
cathode resistor.

Um, ever hear of a selenium rectifier? Mac, early Marantz, Fisher, Dynaco,
etc all had 'em for bias and dc heater applications. Yeah, they *wore out
after 10 years or so, but by then you had the silicon replacements.

Yes, but they were nasty. But for bias, not so nasty as to be
unthinkable. They were common. They didn't realize how toxic selenium
smoke was then, so it's a case of looking back through a different
perspective.

Cantonwine's battery charger book is very informative on them.

Tungar bulbs were another alternative. They had small ones. You wanted
a relay for protection still, though.

[John Stone]

On 7/14/10 8:48 PM, in article
, "Bret L"
wrote:

On Jul 14, 8:45*pm, John Stone wrote:
On 7/14/10 8:37 PM, in article
, "Bret L"

wrote:
*They didn't have cheap silicon diodes, so you needed tube rectifiers,
not only for HV but bias as well unless you wanted to use a battery.
And a relay to open if no bias voltage was there and bring in a
cathode resistor.

Um, ever hear of a selenium rectifier? Mac, early Marantz, Fisher, Dynaco,
etc all had 'em for bias and dc heater applications. Yeah, they *wore out
after 10 years or so, but by then you had the silicon replacements.

Yes, but they were nasty. But for bias, not so nasty as to be
unthinkable. They were common. They didn't realize how toxic selenium
smoke was then, so it's a case of looking back through a different
perspective.

You're backtracking. Fact is, seleniums, not tubes, were the most common
rectifier in 50's and 60's consumer electronics for bias and heater
supplies. And a large chunk of companies used them for B+ rectification as
well. Series wired tv's often had a pair of big ones in voltage doubler
configuration. Another example being your beloved Marantz 7 which used a
half wave selenium stack for B+ and a full wave bridge for heater supply.
I've never seen tubes used in consumer products for bias rectifiers. As for
them being nasty, yeah, they stunk like hell when they blew up which wasn't
very often. As for toxicity, I don't know of anyone who was ever
injured-much less died-from a selenium rectifier. Do you? German companies
like AEG and Siemens made tons of selenium bridges for use in radios and hi
fi gear. The stacks were well sealed to keep the stink contained if they
blew.

[Bret L]

On Jul 15, 8:06*am, John Stone wrote:
On 7/14/10 8:48 PM, in article
, "Bret L"



wrote:
On Jul 14, 8:45*pm, John Stone wrote:
On 7/14/10 8:37 PM, in article
, "Bret L"

wrote:
*They didn't have cheap silicon diodes, so you needed tube rectifiers,
not only for HV but bias as well unless you wanted to use a battery.
And a relay to open if no bias voltage was there and bring in a
cathode resistor.

Um, ever hear of a selenium rectifier? Mac, early Marantz, Fisher, Dynaco,
etc all had 'em for bias and dc heater applications. Yeah, they *wore out
after 10 years or so, but by then you had the silicon replacements.

*Yes, but they were nasty. But for bias, not so nasty as to be
unthinkable. They were common. They didn't realize how toxic selenium
smoke was then, so it's a case of looking back through a different
perspective.

You're backtracking. Fact is, seleniums, not tubes, were the most common
rectifier in 50's and 60's consumer electronics for bias and heater
supplies. And a large chunk of companies used them for B+ rectification as
well. Series wired tv's often had a pair of big ones in voltage doubler
configuration. Another example being your beloved Marantz 7 which used a
half wave selenium stack for B+ and a full wave bridge for heater supply.
I've never seen tubes used in consumer products for bias rectifiers. As for
them being nasty, yeah, they stunk like hell when they blew up which wasn't
very often. As for toxicity, I don't know of anyone who was ever
injured-much less died-from a selenium rectifier. Do you? German companies
like AEG and Siemens made tons of selenium bridges for use in radios and hi
fi gear. The stacks were well sealed to keep the stink contained *if they
blew.

I doubt they killed anyone but they were toxic, people that worked on
lots of them (in bigger apps like elevator boxes) had all sorts of
upper respiratory issues. There were also similar copper oxide
rectifiers.

At the time, though, they did give halfway decent service. I would
not run any today but would replace with diodes and dropping
resistors.

If you read POOGE-1 by Jung and Marsh, i believe, you know the PS
waas the weakest part of the original Marantz 7 and no one today would
emulate it.