On 6/01/2020 4:29 am, Chuck wrote:
On Sun, 5 Jan 2020 15:37:08 +1100, Trevor Wilson
wrote:

On 5/01/2020 2:13 pm, wrote:
On Thursday, 2 January 2020 01:33:30 UTC, Trevor Wilson wrote:
On 2/01/2020 12:07 pm, tabbypurr wrote:
On Wednesday, 1 January 2020 20:18:43 UTC, Trevor Wilson wrote:
On 1/01/2020 4:20 am, wrote:
On Tue, 31 Dec 2019 09:43:42 +1100, Trevor Wilson
wrote:

On 31/12/2019 9:34 am, wrote:
On Tue, 31 Dec 2019 09:27:29 +1100, Trevor Wilson
wrote:

On 31/12/2019 5:50 am, wrote:
On Tue, 31 Dec 2019 05:21:03 +1100, Trevor Wilson
wrote:

On 31/12/2019 4:45 am, wrote:
Well, I peeked inside the amp and took off the transformer covers.
There are indeed 3 transformers. From what folks have said I half
expected to find some sort of weights under the xmfr covers because
the amp is so heavy. Nope, just copper and iron.
Inside the amp are no solid state devices but for the Bluetooth
module, which connects to the input through a relay. So the amp
switches automatically between inputs depending on whether the
Bluetooth module is recieving a signal.
On to the tubes. I turned the amp on again last night and just
listened. After a while, maybe 45 minutes, I heard a crackle. Looking
carefully at the tubes I noticed that one of the EL34 tubes was
glowing brighter at the top than the other EL34 tube. There is a mica
disc in the top of the tube and a little of the filament protrudes
through a small hole in the mica. And this is what was glowing
brighter.
I tapped the tube and heard the noise coming out of just the left
speaker. Tapping the right side tube produced no noise.
I though that maybe one tube was getting more voltage than the
other so I waited for things to cool down and then swapped tubes. The
same tube got brighter but was now on the right side. So the tube must
be bad because the problem travels with the tube and the same tube
gets brighter no matter which side it is plugged into.
So, anybody have suggestions on tubes? I'm not an audiophile. My
hearing isn't good enough. I don't think matched pair tubes would make
any difference to me ears. But I can hear well enough so a fairly high
quality tube set would be desirable. And I do think I should get a
pair so that they will hopefully last tghe same amount of time.
Thanks,
Eric


**Sure. Dump it and buy a decent solid state amp. Almost anything will
be far more reliable and better sounding. Why bother with a cheap,
Chinese tube amp?
Because I like it. It sounds good.

**How do you know? Have you compared it to a decent, inexpensive solid
state amp? Are you certain that it is not simply acting as an expensive,
unreliable filter?

People spontaneously comment on
how good it sounds.

**How would they know? By a very considerable margin, loudspeakers and
room acoustics, dominate the sound of a system. All amplifiers, unless
they are faulty (like cheap, ****ty tube amps) sound very similar.
Particularly to listeners who have little of no familiarity with the
system.


Not how it sounds almost as good as a solid state
amp. And I like tubes.

**Well, I guess we're different. I like my system to provide a close
illusion of the original musical event. No tone controls and no
(audible) distortion. If that result can be achieved with tubes (and it
can, but it costs a lot), then great. SS does it cheaper and more reliably.

Are you grumpy today?

**Well, yes, but that's another story. I'm very angry with my global
warming denying government. I'm stuck with the morons for a few more
years. Just as Americans are stuck with man with the intellect and
maturity of a 10 year old boy for POTUS. Still, there is hope. Not much
though.

I suggest you try a decent, inexpensive SS amp. Dump the tubes. Good
tube amps do sound pretty damned good. Trouble is, they are REALLY
expensive. For budget sound systems, SS does it better.
On the 1st Satuday in August I will be roasting my 25th pig. It's an
annual party. Why don't you fly up and camp out? We have 10 or 12
wooded acres. I have an extra tent. It's a good party and you can
listen to my ****ty tube amp and grouse about it while we grouse about
our ****ty "leaders". I'm sure the amp will sound better than Trump.
Eric


**Thank you, but no thanks. Pork is not a meat I like to eat.

Have you tried a decent, but inexpensive SS amp?

I'd rather listen to, well, ANYTHING, but Trump.
Yeah. I have a decent SS amp. Good speakers on it too. I still like my
tube amp. No accounting for taste, eh?


**Indeed. Your tube amp is acting as an expensive, unreliable tone
control. When you finally realise that, you may decide that another
approach is appropriate. Or not.

Think about it logically: EVERYTHING in front of your tube amp is solid
state. There are literally hundreds of semiconductor junctions in the
recording chain and any digital reproduction devices in your part of the
chain. The only thing your tube amp is doing, is to alter the original
sound, via linear and non-linear introduced distortion.

For me and my system, ALL forms of distortion interfere with the
original musical event and are not tolerated.

I get the attraction of tube amps to some people. They look different
and they have this retro appeal to hipsters and others. Sonically, they
are a waste of time, money and effort.

Someone's never had a good tube amp.


**Now you're just being silly. I've had the opportunity to listen to a
VERY wide range of amplifiers in my systems (numbering in the hundreds).
More than most, as my job is fixing them. I listen to all of them as
part of my test procedure. I've been servicing tube amps for more than
50 (gulp) years. I've built few too. In fact, I can tell you that a
REALLY good tube amp, when driving suitably benign impedance speakers,
will sound almost indistinguishable from a good SS amp. In fact, I was
fooled once. I thought I was listening to a Krell, when I was listening
to a rather good Audio Research. Here's the thing:

Really good tube amps sound just like really good (or even not so good)
SS amps. I can state that from personal experience.

Cheap, ****ty tube amps sound very different from really good tube amps
(and most SS amps). They sound different because they introduce various
forms of distortion.

Look at the frequency response curve, when operating into a typical
speaker load (black curve), of a ****ty tube amp:

https://www.stereophile.com/content/...r-measurements

I chose that amp, because it was easy to find on the Stereophile site.
There are many more examples.

Here is the response of another ****ty tube amp, with audible flaws):

https://www.stereophile.com/content/...r-measurements

Here is the response of an amp that I felt was acceptable in my system
(still far from perfect):

https://www.stereophile.com/content/...r-measurements


Here is the response of a cheap SS amp, which I felt sounded as good as
ANY tube amp (power output limitations excepted):

https://www.stereophile.com/content/...r-measurements

Far from perfect, but not too horrible.

You'll note the audibly significant frequency response variations
inherent to most tube amps. This form of linear distortion is VERY
audible. And not acceptable to me. This and other distortions do not
exist in most competently designed SS amps.

I've also built a few tube amps and listened to a fair number of valve & tranny amps, though not 100s. Sure their foibles are different, with neither being perfect. My experience fwiw is I've never found any tranny amp that has the sound quality of a Quad II or a Sansui 500A. I used to be more involved in audio, not much now.


**I Would sincerely hope that no reputable amplifier manufacturer (tube
or SS) would try to build an amp that sounds as bad as either. Both have
serious measurable and audible flaws.
The 500A also had heat related drifting cap values in the MPX circuit
which caused intermittent stereo reception .


**That type of fault can afflict any analogue receiver. SS or tube.

--
Trevor Wilson
www.rageaudio.com.au

In article ,
says...

I have always thought a Audio Sinewave going through a Transistor would
come out as a Squarewave, not a Sinewave.

To my way of thinking a Sinewave is Pure Audio, a Squarewave would make
the signal sound distorted (a bit?).

Does it happen as I imagine, or am I way off base.

I never seen the pattern of the output on an oscilloscope so I don't really
know.



It all depends on the circuit. If just fed in to a transistor the
output would be a square wave, more or less.

YOu use resistors to bias a transistor in to a linear type amplifier if
you want the output wave form to be the same as the input except larger.
It will usually be inverted depending on how you make the circuit.


Look up class A, Class B and Class C amplifiers. The class A is linear
, class B (in audio amplifiers) usually has 2 trasistors in push pull so
the wavefor will not be distorted. The class C amp looks like a bunch of
pulses if biased far enough. The class B will be distorted if the
transistors are not in push pull. The class C will really be distorted.

Given equal quality amps, the tubes will be driven into saturation on
very strong signals slightly different than the solid state ones
usually.

I have such a tin ear that I doubt I could tell the difference in a $
100 system and a $ 10,000 system. There have been some studies that
people with very good ears can tell the difference the insturments could
not detect back in the late 1960s.

Vos non potestis figere stultus. Invicta est ignorantia, et addere illud aggregatum mortiferum.

On 1/6/20 7:20 AM, wrote:
Vos non potestis figere stultus.

You can't fix stupid, but a shot of WD-40 in the mouth
will quiet it down.


--
"I am a river to my people."
Jeff-1.0
WA6FWi
http:foxsmercantile.com