Audio, hi-fi and car audio - Tube amplifiers

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Hi,

I am new in tube amplifiers. I would like to buy one. Would you please
advice me of good models of tube amplifiers.

Thanks,

Vasilis

Hi,

Usually I listen to classic rock music. My speakers are Boston
Acoustics VRM90.
I would like to spend around 1000 pounds on such a tube amplifier.
I am planning to buy a jolida JD100 CD player.
I hope that this info is adequate.

Thanks,

Vasilis

wrote in message
oups.com...
Hi,

I am new in tube amplifiers. I would like to buy one. Would you please
advice me of good models of tube amplifiers.

**Can't go wrong with an Audio Research VT100-III, combined with a Conrad
Johnson Premier 16. Absolutely neutral and very accurate sound quality.

Of course, you could achieve EXACTLY the same result with a good quality SS
amp, for a whole lot less money. That will never impress your friends
though.

--
Trevor Wilson
www.rageaudio.com.au

Where do you live and where are you thinking of buying from?

=== Andy Evans ===
Visit our Website:- http://www.artsandmedia.com
Audio, music and health pages and interesting links.

" wrote:

Hi,

I am new in tube amplifiers. I would like to buy one. Would you please
advice me of good models of tube amplifiers.

On friday you said you would like to build a tube amp.

Now you are saying you would just like to just buy a tube amp.

You might like to familiarise yourself with tube amps generally before
buying anything,
let alone building one, which for the novice is a very complex thing to
do.

A known tube amp hater pointed you in the terrible direction
of one of the the worst designs ever to be seen at

http://members.aol.com/aria3/output.htm

This type of audio amp uses tubes to be directly connected to the load,
and it is called an OTL, or output transformerless amplifier.
They are notoriously unreliable.
But some sound excellent while working.

Tube amps with output transformers are able to achieve a better match
between the load and the
tubes so the matching of tubes is relatively unimportant, and the
reliablity is far better,
so that 5,000 hrs can be expected from an output tube such as a 6550.

If you listen 2 hrs per day, 365 days per year, you get 6.8 yrs out of an
output tube.
Whilst some solid state gear might last that long without a service, a lot
do not,
and the cost of a fix for a high end SS amp may well be more than the cost
of re-tubing
in say 6 years.

I suggest you join an audio club, make friends with the members, and
listen to their systems.
There are some dirt cheap chinese amps around, and then some very
expensive
amps from CJ, ARC, or Jadis et all.

But I strongly suggest you vote with your ears after some trialing of
available amps,
and if you hear nothing special with an ARC, then don't buy one.

There are some good second hand deals around, and CJ and ARC hold value
ok,
And then there is Leak, Quad, Dynaco, Radford, and old samples in good
condition
may be OK as an entry level thing, but you need someone into tube gear to
be able to sort problems without ripping you off.

The audio club may know guys like that.

Patrick Turner.

Thanks,

Vasilis

In article , Patrick Turner
wrote:

[snip]

A known tube amp hater pointed you in the terrible direction of one of
the the worst designs ever to be seen at

http://members.aol.com/aria3/output.htm

This type of audio amp uses tubes to be directly connected to the load,
and it is called an OTL, or output transformerless amplifier. They are
notoriously unreliable. But some sound excellent while working.

I assume you are referring to Trevor above. I don't have direct experience
of the valve amps he quoted, but my (perhaps unreliable) recollection is
that they have had good reviews in magazines from reviewers that
like/prefer valve amps.

Tube amps with output transformers are able to achieve a better match
between the load and the tubes so the matching of tubes is relatively
unimportant, and the reliablity is far better, so that 5,000 hrs can be
expected from an output tube such as a 6550.

It is probably correct that the power efficiency tends to be better using
transformers. However I'd avoid using 'match' here as speakers tend to be
designed assuming the power amp is a low-impedance voltage source.

If you listen 2 hrs per day, 365 days per year, you get 6.8 yrs out of
an output tube. Whilst some solid state gear might last that long
without a service, a lot do not,

No idea what percentage of what commercial designs you call "a lot".
Perhaps you could specify?

FWIW most of the amps I use are 20+ years old, and from personal
experience, and working in the field in the past I'd say most of the SS
amps I know about survive quite well for well over 6.8 years with no
necessity for any service. Don't have any reason to assume that the designs
I knew were unusual. Hence I would not have said "a lot" as you do above.
I might have said "a few", but I don't know what percentage, designs,
etc, you have evidence on.

That said, I assume that you'd regard this as irrelevant as the OP was
asking for a valve amp recommendation, not a comparison of opinions on
reliability and long term service costs: valve versus transistor. :-)

and the cost of a fix for a high end SS amp may well be more than the
cost of re-tubing in say 6 years.

In some cases, perhaps, but perhaps a misleading generalisation. I'd say
that SS amps tend not to go wrong as often as you seem to imply, and SS
devices are cheaper than valves. Hence I have my doubts that the probable
running/reliability costs for SS would exceed valve in timescales of the
order of a decade. So I'd advise the OP to take your comments on
reliability with some caution if they think this is a relevant issue.

So far as I am concerned, both SS and Valve kit can be quite reliable
and work well over long periods, but after some years a change of valves
can become advisible as you say. Hence if the OP is willing to pay a fair
amount for a decent design, I would hope this was not much of an issue.

Agree with the comments about finding people who already use or understand
valve amps if you are interested. And on listening first if you can. That
may well be more useful than comments here as we may not really know
exactly why the OP would personally prefer one choice to another.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Jim Lesurf" wrote in message
...
In article , Patrick Turner
wrote:

[snip]

A known tube amp hater pointed you in the terrible direction of one of
the the worst designs ever to be seen at

http://members.aol.com/aria3/output.htm

This type of audio amp uses tubes to be directly connected to the load,
and it is called an OTL, or output transformerless amplifier. They are
notoriously unreliable. But some sound excellent while working.

I assume you are referring to Trevor above. I don't have direct experience
of the valve amps he quoted, but my (perhaps unreliable) recollection is
that they have had good reviews in magazines from reviewers that
like/prefer valve amps.

Tube amps with output transformers are able to achieve a better match
between the load and the tubes so the matching of tubes is relatively
unimportant, and the reliablity is far better, so that 5,000 hrs can be
expected from an output tube such as a 6550.

Agreed
OTL is not recommended for any but the stoutest of hearts, and
definitely not for a newbee.

Iain

Jim Lesurf wrote:

In article , Patrick Turner
wrote:

[snip]

A known tube amp hater pointed you in the terrible direction of one of
the the worst designs ever to be seen at

http://members.aol.com/aria3/output.htm

This type of audio amp uses tubes to be directly connected to the load,
and it is called an OTL, or output transformerless amplifier. They are
notoriously unreliable. But some sound excellent while working.

I assume you are referring to Trevor above.

Nope, never assume anything while I am around; it was arny who gave the
references.

I don't have direct experience of the valve amps he quoted, but my (perhaps
unreliable) recollection is
that they have had good reviews in magazines from reviewers that
like/prefer valve amps.

OTL tube amps have appalling load matches to the tubes.
It'd be like using a couple of bjts to drive 0.2 ohms.

Tube amps with output transformers are able to achieve a better match
between the load and the tubes so the matching of tubes is relatively
unimportant, and the reliablity is far better, so that 5,000 hrs can be
expected from an output tube such as a 6550.

It is probably correct that the power efficiency tends to be better using
transformers.

Far better.

However I'd avoid using 'match' here as speakers tend to be
designed assuming the power amp is a low-impedance voltage source.

NFB normally converts any current source into a voltage source.

If you listen 2 hrs per day, 365 days per year, you get 6.8 yrs out of
an output tube. Whilst some solid state gear might last that long
without a service, a lot do not,

No idea what percentage of what commercial designs you call "a lot".
Perhaps you could specify?

Enough to keep me busy repairing the darn things.
And I am only one of maybe 50 repair blokes in a town of 300,000 ppl.

FWIW most of the amps I use are 20+ years old, and from personal
experience, and working in the field in the past I'd say most of the SS
amps I know about survive quite well for well over 6.8 years with no
necessity for any service. Don't have any reason to assume that the designs
I knew were unusual. Hence I would not have said "a lot" as you do above.
I might have said "a few", but I don't know what percentage, designs,
etc, you have evidence on.

That said, I assume that you'd regard this as irrelevant as the OP was
asking for a valve amp recommendation, not a comparison of opinions on
reliability and long term service costs: valve versus transistor. :-)

and the cost of a fix for a high end SS amp may well be more than the
cost of re-tubing in say 6 years.

In some cases, perhaps, but perhaps a misleading generalisation. I'd say
that SS amps tend not to go wrong as often as you seem to imply, and SS
devices are cheaper than valves. Hence I have my doubts that the probable
running/reliability costs for SS would exceed valve in timescales of the
order of a decade. So I'd advise the OP to take your comments on
reliability with some caution if they think this is a relevant issue.

SS amps go phut as often as a TV.
Mine has had 3 failures since 1982.
Its been parked for 6 years since then, and since the last Olympics
when it went bung, and I decided TV was a bad influence anyway....

The 1975 SS AM/FM receiver with 30 watt amps in it has had two services before
I parked it in a cupboard.

So I have spent my hundreds fixing modern "reliable" appliances....

So far as I am concerned, both SS and Valve kit can be quite reliable
and work well over long periods, but after some years a change of valves
can become advisible as you say. Hence if the OP is willing to pay a fair
amount for a decent design, I would hope this was not much of an issue.

Agree with the comments about finding people who already use or understand
valve amps if you are interested. And on listening first if you can. That
may well be more useful than comments here as we may not really know
exactly why the OP would personally prefer one choice to another.

Vote with the ears on the sound, and share the experience of other owners
of what its like to own something.

Patrick Turner.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

In article , Patrick Turner
wrote:

Jim Lesurf wrote:

In article , Patrick Turner
wrote:

[snip]

A known tube amp hater pointed you in the terrible direction of one
of the the worst designs ever to be seen at

http://members.aol.com/aria3/output.htm

This type of audio amp uses tubes to be directly connected to the
load, and it is called an OTL, or output transformerless amplifier.
They are notoriously unreliable. But some sound excellent while
working.

I assume you are referring to Trevor above.

Nope, never assume anything while I am around; it was arny who gave the
references.

OK. His name/posting has not appeared in this thread so far as I can see.
It may be that my ISP's news servers haven't picked it up for some reason.
Since I've not seen his name in this thread I assumed you were referring to
Trevor, who has appeared, and suggested SS as an alternative.

Can't comment on what Arny has said as I haven't read it.

I don't have direct experience of the valve amps he quoted, but my
(perhaps unreliable) recollection is that they have had good reviews
in magazines from reviewers that like/prefer valve amps.

OTL tube amps have appalling load matches to the tubes. It'd be like
using a couple of bjts to drive 0.2 ohms.

Yes, I'd agree.

Tube amps with output transformers are able to achieve a better
match between the load and the tubes so the matching of tubes is
relatively unimportant, and the reliablity is far better, so that
5,000 hrs can be expected from an output tube such as a 6550.

It is probably correct that the power efficiency tends to be better
using transformers.

Far better.

However I'd avoid using 'match' here as speakers tend to be designed
assuming the power amp is a low-impedance voltage source.

NFB normally converts any current source into a voltage source.

This depends upon the open loop impedance, amount of feedback, etc.

The snag is that my impression is that some valve designs with output
transformers only use a modest amount of feedback. As a result they can
have output impedance of the order of 0.5 Ohms. (e.g. the amp Iain
mentioned in another thread recently). This level of output impedance
allows for quite audible changes in the response with loudspeakers whose
input impedance varies with frequency. Hence in this context such amps
aren't really working as voltage sources as their finite output impedance
is affecting the results.

However my (minor) concern is that 'match' implies seeking to make the
source and load impedances the same. This isn't what is usually assumed or
required for driving the speaker as the voltage source model assumes a
source o/p impedance which is 'small' compared with the load impedance. I
was therefore trying to agree with your comments w.r.t comparing OTL and
using a transformer, but being wary of the word 'match' for this.

If you listen 2 hrs per day, 365 days per year, you get 6.8 yrs out
of an output tube. Whilst some solid state gear might last that long
without a service, a lot do not,

No idea what percentage of what commercial designs you call "a lot".
Perhaps you could specify?

Enough to keep me busy repairing the darn things. And I am only one of
maybe 50 repair blokes in a town of 300,000 ppl.

Well, that still may not tell us what you seem to assume...

It does not tell us what percentage of units (either SS or valve) actually
in use have to be returned for service within, say, 10 years. To do that
you'd need to know how many units are actually in service for such a
period. Then take into account how many more SS units there may be out
there of that kind of age than valve units. Plus some other factors if you
wish to use this as a basis for commenting on the kind of equipment someone
serious enough to spend up to 1000 UKP on an amp might be looking for.

No idea what the real figures may be, but let's consider some simple
guesstimates...

Assume 2 people per house = 150,000 households.

Assume 50% have audio amps = 75,000 amps

Assume 1% are valve = 750 valve amps and still essentially 75,000 SS.

Assume both have a service-required/year rate of 1%
= 7.5 Valve services/year and 750 SS services per year.

Assume all services equally and randomly distributed to 50 repair
centers.
= 0.15 valve and 15 SS services per repairer per year.

On this sort of basis a repairer might have to fix far more SS units
per year than valve units, but without this telling them much about
the relative reliabilties. Have to beware of selection effects
or uncontrolled factors.

I'm sure that some of the above assumptions won't be correct. However
they do show that you may have to take care when trying to translate
your comment into a deduction about "a lot" of SS amps. Particularly if
you are talking about figures like the above that may lump together
cheap or unreliable models with more expensive or more well-built ones.

FWIW when I worked for a UK manufacturer we used to have an excellent
service and repair section, and kept detailed records. I also knew then,
and since, a few people who repair sets in the UK, and other manufacturers,
etc. The company I used to work for did also transform themselves into a
contract repair company and now do work for lots of people who don't find
there is enough work in this any more to do it themselves. (See the
comments I make w.r.t. TV repair elsewhere.)

Although I have not memorised any figures my impression is that it might be
unreliable to say as a generalisation that "a lot" of units required
service in the space of 10 years or so and that this would be misleading
if the implication is that SS units are distinctly less reliable than valve
ones. This may depend upon the definition of "a lot", though, and I am sure
that some specific models or batches have problems.

Hence if the OP is happy to spend up to 1000 UKP on an amp - SS or valve -
I'd expect him to be able to buy an amp that is likely to work reliably
over such a period - the only possible exception being the desirability at
some point to fit replacement valves. However if he is happy to spend 1000
UKP on a valve amp I see no reason to think he would be deterred by having
to re-valve at some point. Comes with the territory.

[snip]

SS amps go phut as often as a TV.

That may be so, although I have doubts. FWIW We replaced our 25 year old TV
about two years ago. It was still working fine. Replaced as we wanted a
widescreen set with scart sockets, not because it had broken down. My
experience with earlier TV's (both mine and friends') is similar. i.e. items
like this get replaced as people want the newer model with the latest
whizz-wheels. But again, this isn't really reliable statistical evidence.

FWIW My recollection is that when we had valve TVs years ago, that calls
to the repair man were more common. Mainly to replace valves. Indeed, we
used to have nearby high street shops that did this. Such things vanished
later on as with SS units many shops contracted any repair work back to the
makers or a central agent as it wasn't worth their while to keep a
repairman employed any more just for the shop.

Mine has had 3 failures since 1982. Its been parked for 6 years since
then, and since the last Olympics when it went bung, and I decided TV
was a bad influence anyway....

Well, your conclusion here may well be a good one. :-)

The 1975 SS AM/FM receiver with 30 watt amps in it has had two services
before I parked it in a cupboard.

The problem is that although the units you quote imply a typical time
between services of around 10 years we can't really say how reliable that
is as a guide for what you said previously.

I feel that much more info would be required for someone willing to spend
1000 UKP on an amp. He isn't thinking of buying either a 30-year-old SS
receiver or a TV. I am not arguing against his preference for valve, which
I assume he has formed on the basis of listening, etc. Just that for the
kind of purchase and price he is considering I see no reason to feel that
SS designs would be less reliable. If he were comparing a 1000 UKP amp
with a 100 UKP one I might think differently, depending on the details.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html