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Building a Tube Amp

E

Eeyore

Jan 1, 1970
0
Jan said:
Today, with GHz FPGAs and very fast DSPs, I think there is hardly any problem
doing simple things like that.

And who's going to code every nuance of every control setting of every amplifier and speaker
combination ever made ?

It IS easier to use the real thing. Flying a real plane IS more satisfying than Flight Simulator in
the same way.

Graham
 
E

Eeyore

Jan 1, 1970
0
Jan said:
That whole tube stuff is marketing, just like oxygen free cables.

That would be largely true in the hi-fi market but clearly you have zero experience of 'music
making'.

Graham
 
E

Eeyore

Jan 1, 1970
0
Tim said:
Not so. Yes, the technology enables it, but that leaves the limiting
factor of our understanding of the mechanisms at work modifying the
sound, and the labor involved in replicating them in DSP.

Agreed in spades.

I know guitarists who've tried the commercial examples currently available. They play with them as
toys for a while then forget them.

Graham
 
E

Eeyore

Jan 1, 1970
0
Jan said:
The issue is 'can we make a tube sound at low level'.
Well any diode clipper does that.

That is NOT a 'tube sound'.

You clearly know so little about this why don't you just back off and leave it to the experts ? You've
always been a know-it-all 'bighead' and it really shows here.

Budge out and leave the discussion to people who know what they're talking about.

Graham
 
E

Eeyore

Jan 1, 1970
0
Robert said:
"Tube distortion"????
When i was i the Army (1960's) 3 of us got together, designed and
built an amplifier around "midnite requisition" tubes and transformers.
Used regulated DC filaments turned on before B+, cascode B+ regulator.
THD and IMD was not measureable via the HeathKit meters; total hum
and noise was better than -60dBm and did not change with open or shorted
input.

Which would be laughed at today. Today's test kit is scary !

Oh yes, nominal output rating was 80 watts if i remember correctly
(push-pull paralell KT66 as KT88s were not available via midnite
requisition).

Did you know the KT66 was originally designed for radar PPI deflection coils ?

Graham
 
J

Jan Panteltje

Jan 1, 1970
0
There were people saying this in the 70s.

They were wrong then too !

No there were right.

Did it ever occur to you that if you listen to a recording
of one of those guitars with tube amps you like so much,
that you hear it through a normal amp?

A few people have tried hybrids but they all sank
without trace.

I was not talking about the idiotic idea of putting a double triode
in the input stage of a solid state amp, or worse a computer motherboard, like here:
http://www.digit-life.com/articles2/aopentube/
I was talking about real signal processing, analog and digital.
 
E

Eeyore

Jan 1, 1970
0
Tam said:
I suspect if you really wanted to, you could take a 100W transistor amp and
make it sound like a 50W tube amp. Just put in the tube type distortion
before the transistor amp goes non linear. I think the tube amps also used a
lot less audio feedback and had higher output impedance.

Been tried many times, never sounds right.

Graham
 
J

Jan Panteltje

Jan 1, 1970
0
That would be largely true in the hi-fi market but clearly you have zero experience of 'music
making'.

Graham

Hell, I played trumpet and guitar.

Come of it, it is all marketing, although I think the modern kids will no longer fall
for the snake oil, and just use a distorton box or program.
You will get over it.
I got over 'HiFi' when I moved house, and everything sounded different due
to different acoustics.
 
J

Jan Panteltje

Jan 1, 1970
0
And who's going to code every nuance of every control setting of every amplifier and speaker
combination ever made ?

Nobody, because most people know it is the music, not so much the acoustics,
or reproduction channel.
But many solutions exist to make interesting distorted sounds for guitar.

There is a small minority of tubophiles, audiophiles, that has their own
ideas and standards.
Those people fork out a lot of money for oxygen free cables, tube amps,
what not.
There is a whole business living from them.


It IS easier to use the real thing.

That is why solid state is everywhere :)
 
J

Jan Panteltje

Jan 1, 1970
0
Do you never attend live performances ?

Graham

We had plenty of live performances form pop bands and star in the studio,
yes with plenty mikes. And plenty volume too.
I did not look what was in their stuff, probably solid state.
 
E

Eeyore

Jan 1, 1970
0
bg said:
Tim Wescott wrote

Most excellent post tim,
I'd like to add that a tube guitar amp is about art, not engineering.

A bit of both. I assisted design a tube / valve guitar amp myself which was very
highly regarded at the time btw. You'll even see them still occasionally on
ebay. There was some technology in there. As ever it was me that had to rewind
the original rather poor prototype output transformer. I never do seem to be
able to get away from magnetics !

I think if there was an alternative, any guitarist would gladly dump these
overpriced and overweight clunkers any day.

Too right and for a while a company in the UK called H-H made SS guitar amps.
They were popular for a while because they suited certain playing styles (esp
jazz / jazz rock) but they faded away.

My fave guitar amp is either the AC30 or the Fender Twin Reverb. Or for *raw*
power a Marshall JPM100.

You should see Mr Knoppler's collection though !

Graham
 
R

Rich Grise

Jan 1, 1970
0
If you want a sample of one, I can email my brother and ask what his band,
Tamarak, uses:
http://www.tamarak.iwarp.com/
but I don't know how long he'll take to reply.
Not long at all:
I wrote him: (here's his pic: http://www.tamarak.iwarp.com/dan.html )
---<quote>---
There's a discussion going on in one of my newsgroups
(about the virtues of tube vs. solid-
state (i.e., transistor) amps, and some guy was wondering what's in
typical use today.

So, what kind of equipment are you guys using, and what have you
historically used? (I want to contribute something other than fluff
to the discussion, and, I guess, brag on you (Hey! My brother's
FAMOUS!!!!) ;-)
---</quote>---

And he responded

---<quote>---
Solid state is used for almost everything with the exception of a lot of
guitar amplifiers. I use a 40 watt amp that has 2 tubes. I guess I'm
"old school" feeling that the basic design they used in the forties and
fifties was the pinnacle. Tube amps give you a nice warm sustain without
the harsh edges. They work well for blues for example. Those big stacks
of Marshall amps in hard rock concerts are all tube amps.

When I was playing a lot of country music, I used a solid state amp.
Nice and bright for that "twang".

The most up to date stuff in concerts now is having no amps on stage,
but a wireless feed to processors that digitally "model" any number of
amp sounds, then sending it back to stage in the monitor mix. They are
getting awfully close to the classic sound. It's a matter of taste, I
guess.

After all, some people think that vinyl records sound the best.
---</quote>---

Hope This Helps!
Rich
 
J

Jan Panteltje

Jan 1, 1970
0
Jan said:
Eeyore said:
Wrong type of distortion. Compare the transfer characteristics.
Tubes produce more even-order harmonic distortion, transistors odd.

You should read 'semiconductors' in the widest sense.
As I pointed out AD - EPROM[s}- DA can make any curve,

ADC -> EPROM -> DAC cannot do anything involving time (reverb,
echo) or non-instantaneous level (compression) or frequency
(high pass, low pass), and most certainly cannot emulate a
tube amp. It can be done in software, but not with a simple
lookup table replacement of each ADC reading.

Think for a moment, put a var gain amp before and after the AD-EPROM-DA,
now you can change clip level by increasing the gain in the first,
and decreasing the gain in the second.
I never claimed I would do echo that way,
I have echo software here I wrote myself for use in CB radio on the PC.
It also does AGC, and equaliser,.
Add a parametric equaliser and you can make speaker resonance look alike,
there is a whole lot of things at your disposal once you go DSP or digital.
Delay and echo almost comes naturally.

You do know the difference between 'curve' and other effects I hope.
 
R

Rich Grise

Jan 1, 1970
0
No it's totally mainstream. You have it exactly the wrong way round.

Depends which stream you're calling "main". ;-) John probably likes
big bands and classics. ;-)

Cheers!
Rich
 
E

Eeyore

Jan 1, 1970
0
Jon said:
Even passive components contribute
to modifying the sound in some way.

No. Forget that, it just makes you sound silly.

I don't know how much of it is hocus pocus but what I do know is that a tube
amp sounds better to play on than digital. Digital tends to not "feel"
alive. I guess these guys are not musicians and can't appreciate the finer
aural aspects of such things. What I do know is that there are quantitative
differences between as simple tube amplifier and a transistor amplifier. I
also know that almost all professional rock guitarists who rely on
distortion will not use solid state.

All you have to do is stick one of each in SPICE and the differences will stick
out like a sore thumb !

Graham
 
E

Eeyore

Jan 1, 1970
0
Jan said:
You have never used spice?

Which will PROVE his point ! I'd hate to try and model a typical output
transformer though !

Graham
 
E

Eeyore

Jan 1, 1970
0
Rich said:
Good Luck finding transformers! The logical thing to do here is to start
browsing surplus stores, I'd think.

They're easy to come by. Just expensive.

Graham
 
J

Jan Panteltje

Jan 1, 1970
0
That is NOT a 'tube sound'.

You clearly know so little about this why don't you just back off and leave it to the experts ? You've
always been a know-it-all 'bighead' and it really shows here.

Budge out and leave the discussion to people who know what they're talking about.

Graham

Wow, the rabbit gets upset, well we will upset you some more, tubophile.
Actually I think you know what you are talking about,and it is just
marketing talk for your own ideas, unfortunately it stops innovation,
and misleads people into buying antique tube stuff.
And it has nothing to do with new design.
 
J

Jon Slaughter

Jan 1, 1970
0
Kevin Aylward said:
Not necessarily. After being a long time valve man, its surprising just
how good some ss effects can be.

For distortion tubes are the winner... A good ss/modeler isn't bad and
usually has more variety but it just can't be the distortion. This is not to
say that one day it might change... but not today. Although it is getting to
a point where many people will sacrifice the tubes for a ss for the economy.

I used to use a tube amp, but now can't be f%^&%ed with the weight. I now
use a Marshall AVT150 transister job, although it does have one ECC83 in
it. However, not for its distortion. I am happy with it, that is after I
had to cut and rewire its effect loop as the damm f%^*&sh£$ "design" techs
at Marshal have no idea that a || loop is useless in a guitar amp. Like,
if I am using its pre-amp distortion, how the f^&* do you insert a volume
pedal in the loop and expect it to control the sound down to zero. Or
like, insert a noise gate and have it actually work?

Um, I had that amp! SELL IT!! It is a POS. Surely you can do better? A
purely modeling amp does better!

For clean sounds tubes don't matter as much but for distortion they are
required... so if you are not using it for distortion then the point is
moot.

Um, you put the volumn pedal in front of the amp! You do realize that some
effects go before the amp and some in the loop?

You don't put chorus/reverb/delay/phaser/etc.. before the amp to be
"distorted" or amplified(you could if purely clean amplification) and you
don't put volume pedals(you could though), wah pedals, compressors on the
loop!

The loop is for effect's after the pre-amp and before the power amp. These
are basically effects you don't want to distort. For effects all other
effects they go before the pre-amp. (and some could go either way)
 
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