Suppose we have poweramp A, 2 * 50 W solid state
and amplifier B, 2*50 W tubed.

First try:
B costs 4 times as much as A, running costs (electricity,
retubing) are much higher, mtbf is worse...obvious, A is the
amplifier with the better price/performance, no ?

Nope, flawed reasoning !
to calculate the true costs, we'll have to take into consideration, that
in case an amplifier fails, this will bring costs that should be taken
into the running costs equation. If the solid state amp happens to
fail with loads of DC on the outputs for a few seconds - speaker
mayhem !!, so that is a hidden, but very real cost. From this you can
see, that what is actually required is a risk analysis of different modes
of failure and the costs involved there. Then there are other hidden
costs: are parts still available for repairs or is a costly
re-engineering
of the amplifier required ? Etc. etc.

Second try: we have taken the previous considerations into account, now
with the proper running costs calculations: B costs 4 times the price of
A,
but running costs for B are half those of A :-) Not a clear cut answer,
now!

still, this is not enough. we haven't even begun to specify, what we
actually
mean by *performance*, so far, implied, only maximum output power came
into the picture. Here are some other criteria that someone could fit
into
performance, weighing factor for each is an individual matter !!
distortion level & spectrum in the 0.05 to 5 Watt output power range,
damping factor, heat generated, looks, ease of use, etc., etc.

Life is about choice,
Rudy

"Ruud Broens" wrote in message
...
Suppose we have poweramp A, 2 * 50 W solid state
and amplifier B, 2*50 W tubed.

First try:
B costs 4 times as much as A, running costs (electricity,
retubing) are much higher, mtbf is worse...obvious, A is the
amplifier with the better price/performance, no ?

Nope, flawed reasoning !
to calculate the true costs, we'll have to take into consideration, that
in case an amplifier fails, this will bring costs that should be taken
into the running costs equation. If the solid state amp happens to
fail with loads of DC on the outputs for a few seconds - speaker
mayhem !!

**Utter nonsense. Almost all SS amps are comprehensively protected against
such an occurrence. OTOH, many tube amps are NOT protected against prolonged
O/C conditions.

, so that is a hidden, but very real cost. From this you can
see, that what is actually required is a risk analysis of different modes
of failure and the costs involved there. Then there are other hidden
costs: are parts still available for repairs or is a costly
re-engineering
of the amplifier required ? Etc. etc.

**No different with tube amps. What happens if a potted output transformer
fails?


Second try: we have taken the previous considerations into account, now
with the proper running costs calculations: B costs 4 times the price of
A,
but running costs for B are half those of A :-) Not a clear cut answer,
now!

**Here's some practical experience for you to take into account. I have a
bench amp in my workshop. It is a 1968 Marantz Model 18 receiver. It
operates 8 hours/day, 6 days a week. It has done so, since 1977, when I
purchased it second hand. It has failed once. I was able to use modern
output devices, as replacements. The cost was minimal.


still, this is not enough. we haven't even begun to specify, what we
actually
mean by *performance*, so far, implied, only maximum output power came
into the picture. Here are some other criteria that someone could fit
into
performance, weighing factor for each is an individual matter !!
distortion level & spectrum in the 0.05 to 5 Watt output power range,
damping factor, heat generated, looks, ease of use, etc., etc.

Life is about choice,

**Indeed. Intelligent, logical choice. Not one confused with lies and
hyperbole.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote in message
...
:
: "Ruud Broens" wrote in message
: ...
: Suppose we have poweramp A, 2 * 50 W solid state
: and amplifier B, 2*50 W tubed.
:
: First try:
: B costs 4 times as much as A, running costs (electricity,
: retubing) are much higher, mtbf is worse...obvious, A is the
: amplifier with the better price/performance, no ?
:
: Nope, flawed reasoning !
: to calculate the true costs, we'll have to take into consideration,
that
: in case an amplifier fails, this will bring costs that should be
taken
: into the running costs equation. If the solid state amp happens to
: fail with loads of DC on the outputs for a few seconds - speaker
: mayhem !!
:
: **Utter nonsense. Almost all SS amps are comprehensively protected
against
: such an occurrence. OTOH, many tube amps are NOT protected against
prolonged
: O/C conditions.
: --
: Trevor Wilson
: www.rageaudio.com.au
:
ahh, yes, but now you're saying the protection itself has infinite MTBF
??
who protects the protector, who guards the guards
Rudy

"Ruud Broens" wrote in message
...

"Trevor Wilson" wrote in message
...
:
: "Ruud Broens" wrote in message
: ...
: Suppose we have poweramp A, 2 * 50 W solid state
: and amplifier B, 2*50 W tubed.
:
: First try:
: B costs 4 times as much as A, running costs (electricity,
: retubing) are much higher, mtbf is worse...obvious, A is the
: amplifier with the better price/performance, no ?
:
: Nope, flawed reasoning !
: to calculate the true costs, we'll have to take into consideration,
that
: in case an amplifier fails, this will bring costs that should be
taken
: into the running costs equation. If the solid state amp happens to
: fail with loads of DC on the outputs for a few seconds - speaker
: mayhem !!
:
: **Utter nonsense. Almost all SS amps are comprehensively protected
against
: such an occurrence. OTOH, many tube amps are NOT protected against
prolonged
: O/C conditions.
: --
: Trevor Wilson
: www.rageaudio.com.au
:
ahh, yes, but now you're saying the protection itself has infinite MTBF
??
who protects the protector, who guards the guards

**Most SS amps have more than one protection system. As for the failure of
VI limit circuits, it is a VERY rare event. IF the VI limit circuits fail
and IF the amp is connected to a short circuit, THEN (and only then) damage
*MAY* occur. OTOH, what protection systems exist for tube amps which are
susceptible to S/C or O/C loads? What protection exists to prevent damage to
output transformers, under extreme HV events?


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote in message
...
case an amplifier fails, this will bring costs that should be
: taken
: : into the running costs equation. If the solid state amp happens
to
: : fail with loads of DC on the outputs for a few seconds - speaker
: : mayhem !!
: :
: : **Utter nonsense. Almost all SS amps are comprehensively protected
: against
: : such an occurrence. OTOH, many tube amps are NOT protected against
: prolonged
: : O/C conditions.
: : --
: : Trevor Wilson
: : www.rageaudio.com.au
: :
: ahh, yes, but now you're saying the protection itself has infinite
MTBF
: ??
: who protects the protector, who guards the guards
:
: **Most SS amps have more than one protection system. As for the failure
of
: VI limit circuits, it is a VERY rare event.

possibly..not my exp. but very rare times very expensive can still add
up, eh ?

IF the VI limit circuits fail
: and IF the amp is connected to a short circuit, THEN (and only then)
damage
: *MAY* occur. OTOH, what protection systems exist for tube amps which
are
: susceptible to S/C or O/C loads? What protection exists to prevent
damage to
: output transformers, under extreme HV events?

do you mean you don't *know* that such protection circuits exist
or that you can't *imagine* these circuits 'being out there' ?

either way, that's a hazardous road to pursue, n'est ce pas ??:-)
cheers,
Rudy
: --
: Trevor Wilson
: www.rageaudio.com.au
:
:

"Ruud Broens" wrote in message
...

"Trevor Wilson" wrote in message
...
case an amplifier fails, this will bring costs that should be
: taken
: : into the running costs equation. If the solid state amp happens
to
: : fail with loads of DC on the outputs for a few seconds - speaker
: : mayhem !!
: :
: : **Utter nonsense. Almost all SS amps are comprehensively protected
: against
: : such an occurrence. OTOH, many tube amps are NOT protected against
: prolonged
: : O/C conditions.
: : --
: : Trevor Wilson
: : www.rageaudio.com.au
: :
: ahh, yes, but now you're saying the protection itself has infinite
MTBF
: ??
: who protects the protector, who guards the guards
:
: **Most SS amps have more than one protection system. As for the failure
of
: VI limit circuits, it is a VERY rare event.

possibly..not my exp. but very rare times very expensive can still add
up, eh ?

**Strawman noted. It is rare for the power transformer to fail in a tube
amp, too, but it happens. Current limit devices RARELY fail first. VI limit
circuits (on their own) are quite reliable. Then there are MOSFETs, which
require no such devices, for protection.


IF the VI limit circuits fail
: and IF the amp is connected to a short circuit, THEN (and only then)
damage
: *MAY* occur. OTOH, what protection systems exist for tube amps which
are
: susceptible to S/C or O/C loads? What protection exists to prevent
damage to
: output transformers, under extreme HV events?

do you mean you don't *know* that such protection circuits exist
or that you can't *imagine* these circuits 'being out there' ?

**I'm sure they do exist. Can you nominate a list of 10 amps which employ
such protection? I can list several thousand (but I do not care to do so) SS
amps which use comprehensive over-current protection, combined with DC fault
protection.



either way, that's a hazardous road to pursue, n'est ce pas ??:-)

**Please stick to English. My French is appalling.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote in message
...
:
: "Ruud Broens" wrote in message
: ...
: Suppose we have poweramp A, 2 * 50 W solid state
: and amplifier B, 2*50 W tubed.

: **Here's some practical experience for you to take into account. I have
a
: bench amp in my workshop. It is a 1968 Marantz Model 18 receiver. It
: operates 8 hours/day, 6 days a week. It has done so, since 1977, when I
: purchased it second hand. It has failed once. I was able to use modern
: output devices, as replacements. The cost was minimal.
:

good! but hardly fair. now you're saying an ss amp owner better be
prepared to do his own repairs, as you can ? ehh, hidden cost: knowhow
Rudy

: still, this is not enough. we haven't even begun to specify, what we
: actually
: mean by *performance*, so far, implied, only maximum output power
came
: into the picture. Here are some other criteria that someone could fit
: into
: performance, weighing factor for each is an individual matter !!
: distortion level & spectrum in the 0.05 to 5 Watt output power
range,
: damping factor, heat generated, looks, ease of use, etc., etc.
:
: Life is about choice,
:
: **Indeed. Intelligent, logical choice. Not one confused with lies and
: hyperbole.
:
:
: --
: Trevor Wilson
: www.rageaudio.com.au
:
:

"Ruud Broens" wrote in message
...

"Trevor Wilson" wrote in message
...
:
: "Ruud Broens" wrote in message
: ...
: Suppose we have poweramp A, 2 * 50 W solid state
: and amplifier B, 2*50 W tubed.

: **Here's some practical experience for you to take into account. I have
a
: bench amp in my workshop. It is a 1968 Marantz Model 18 receiver. It
: operates 8 hours/day, 6 days a week. It has done so, since 1977, when I
: purchased it second hand. It has failed once. I was able to use modern
: output devices, as replacements. The cost was minimal.
:

good! but hardly fair. now you're saying an ss amp owner better be
prepared to do his own repairs, as you can ? ehh, hidden cost: knowhow
Rudy

**Not at all. The amp in question had a 1968 RRP of US$1,200.00. The cost of
repair was less than US$120.00. NO hidden costs, just very high levels of
reliability.


--
Trevor Wilson
www.rageaudio.com.au

"Trevor Wilson" wrote in message
...
: : **Here's some practical experience for you to take into account. I
have
: a
: : bench amp in my workshop. It is a 1968 Marantz Model 18 receiver.
It
: : operates 8 hours/day, 6 days a week. It has done so, since 1977,
when I
: : purchased it second hand. It has failed once. I was able to use
modern
: : output devices, as replacements. The cost was minimal.
: :
:
: good! but hardly fair. now you're saying an ss amp owner better be
: prepared to do his own repairs, as you can ? ehh, hidden cost:
knowhow
: Rudy
:
: **Not at all. The amp in question had a 1968 RRP of US$1,200.00. The
cost of
: repair was less than US$120.00. NO hidden costs, just very high levels
of
: reliability.
:
:
: --
: Trevor Wilson
: www.rageaudio.com.au
:
OK But induction from: "i know an amp, that..." to "all amps..." ,
he, how gullible us tubies r , do you think :-) ??
Rudy

"Ruud Broens" wrote in message
...

"Trevor Wilson" wrote in message
...
: : **Here's some practical experience for you to take into account. I
have
: a
: : bench amp in my workshop. It is a 1968 Marantz Model 18 receiver.
It
: : operates 8 hours/day, 6 days a week. It has done so, since 1977,
when I
: : purchased it second hand. It has failed once. I was able to use
modern
: : output devices, as replacements. The cost was minimal.
: :
:
: good! but hardly fair. now you're saying an ss amp owner better be
: prepared to do his own repairs, as you can ? ehh, hidden cost:
knowhow
: Rudy
:
: **Not at all. The amp in question had a 1968 RRP of US$1,200.00. The
cost of
: repair was less than US$120.00. NO hidden costs, just very high levels
of
: reliability.
:
:
: --
: Trevor Wilson
: www.rageaudio.com.au
:
OK But induction from: "i know an amp, that..." to "all amps..." ,
he, how gullible us tubies r , do you think :-) ??

**What I provided was a practical, real life experience. It is certainly not
unusual.


--
Trevor Wilson
www.rageaudio.com.au

On Tue, 4 Jan 2005 01:51:26 +0100, "Ruud Broens"
wrote:

how gullible us tubies r , do you think :-) ??

Oh no, that's just *too* tempting! :-)

--

Stewart Pinkerton | Music is Art - Audio is Engineering