Maker Pro
Maker Pro

Slashdot - Tubes vs Transistors

J

Jim Thompson

Jan 1, 1970
0
http://slashdot.org/articles/04/07/11/0326248.shtml?tid=141&tid=188

"Say no more... say no more..."

Thanks,
- Win

(email: use hill_at_rowland-dot-org for now)

Yep. Transistor amplifiers designed to distort just like tooooob
amplifiers can't be discerned to be transistor amplifiers in blind
tests.

I find that people who like tooooob amplifiers aren't classic music
aficionados, or if they are, haven't ever been to a live concert hall.

I can spot toooob cross-mod distortion in a Mozart woodwind ensemble
at ANY output level.

Toooobs should be banned as power wasters.

Certainly some jerk is going to complain that transistor amplifiers
hard-clip. ONLY if they're poorly designed.

...Jim Thompson
 
T

Tim Wescott

Jan 1, 1970
0
Jim said:
Yep. Transistor amplifiers designed to distort just like tooooob
amplifiers can't be discerned to be transistor amplifiers in blind
tests.

I find that people who like tooooob amplifiers aren't classic music
aficionados, or if they are, haven't ever been to a live concert hall.

I can spot toooob cross-mod distortion in a Mozart woodwind ensemble
at ANY output level.

Toooobs should be banned as power wasters.

Certainly some jerk is going to complain that transistor amplifiers
hard-clip. ONLY if they're poorly designed.

...Jim Thompson
Do you have any references on designing transistor amplifiers to distort
like tubes?

The rock-n-roll crowd still wants tube final amps, but they're purposely
using the tube distortion (and power supply sag, and "poor" magnetics,
etc.) as part of the music. There's been general rejection of the
obvious solution using a DSP to do the low-level processing then a
_very_ clean transistor final, but I don't know if this has to do with
psychoacoustics or psycho amplifier buyers.
 
J

Jim Thompson

Jan 1, 1970
0
Do you have any references on designing transistor amplifiers to distort
like tubes?

The rock-n-roll crowd still wants tube final amps, but they're purposely
using the tube distortion (and power supply sag, and "poor" magnetics,
etc.) as part of the music. There's been general rejection of the
obvious solution using a DSP to do the low-level processing then a
_very_ clean transistor final, but I don't know if this has to do with
psychoacoustics or psycho amplifier buyers.

Psycho says it all ;-)

I think you can come pretty close to toooob distortion with
diode-soft-limiters in the front-end.

Controlled clipping *can* be done in the output, but it's harder to
implement. The DSP up-front seems like an ideal way to go; if that's
what floats your boat ;-)

I used to have some papers on the subject, but I'm not sure if I still
have them... I'll look around.

My personal approach to low distortion is extreme power capabilities
(as in 400W) which you don't use... a large transient does't clip.

...Jim Thompson
 
E

.:: Evanescence ::.

Jan 1, 1970
0
Um vampiro chado Jim Thompson said:
Yep. Transistor amplifiers designed to distort just like tooooob
amplifiers can't be discerned to be transistor amplifiers in blind
tests.

I find that people who like tooooob amplifiers aren't classic music
aficionados, or if they are, haven't ever been to a live concert hall.

I can spot toooob cross-mod distortion in a Mozart woodwind ensemble
at ANY output level.

Toooobs should be banned as power wasters.

Audiophools, ya know. Those that say "TRANSISTORS SUCK AND I CAN PROVE IT".

[]s
 
R

Rather Play Pinball

Jan 1, 1970
0
I'm not for transistors or tubes. It sounds great on my iPod and that's all
that counts. And it has neither.

;-)
 
K

Keith

Jan 1, 1970
0
I'm not for transistors or tubes. It sounds great on my iPod and that's all
that counts. And it has neither.

Really? Your IPod has no transistors? That surely seems to be strange
talk in an electronics group!
 
K

Keith

Jan 1, 1970
0
Audiophools, ya know. Those that say "TRANSISTORS SUCK AND I CAN PROVE IT".

Change "PROVE" to "HEAR", or perhaps "SENSE", and you have the phools
nailed.
 
B

Ben Bradley

Jan 1, 1970
0
The rock-n-roll crowd still wants tube final amps, but they're purposely
using the tube distortion (and power supply sag, and "poor" magnetics,
etc.) as part of the music. There's been general rejection of the
obvious solution using a DSP to do the low-level processing then a
_very_ clean transistor final, but I don't know if this has to do with
psychoacoustics or psycho amplifier buyers.

The Line 6 "Pod" has been the DSP guitar-amp-modelling standard in
recent years:

http://www.musiciansfriend.com/srs7...9244725/g=home/search/detail/base_pid/482197/

This has been the popular substitute whenever an real amp can't be
used, but I haven't heard of it putting a dent into real amplifier
sales.

So who else has already commented in that slashdot thread before
seeing it here?
 
D

Don Klipstein

Jan 1, 1970
0
The Line 6 "Pod" has been the DSP guitar-amp-modelling standard in
recent years:

http://www.musiciansfriend.com/srs7/sid=040711183006068154015079244725/ g=home/search/detail/base_pid/482197/

This has been the popular substitute whenever an real amp can't be
used, but I haven't heard of it putting a dent into real amplifier
sales.

I heard it a year or two ago. I did not think it sounded all that
great.

I have played around in this area, and I have noticed a few things:

1. The desirable sound results heavily from a combination of soft
clipping and hard clipping. Other nonlinearities are much less important.

2. It is often good for the signal should have a fairly spiky or "bright"
waveform prior to soft clipping. One desirable feature of "Fender" amps
is "darkening", in which a spiky waveform is squashed in a way that
reduces treble content when soft clipping occurs. This requires a soft
clipping milder than that achieved with silicon diode clipers.
Silicon diode clippers, in combination with hard clipping, make a good
sound like that of some "Marshalls". The soft clipping is harsher there
and produces more noticeable harmonic content, so "darkening" is not as
apparent. Many diode clippers have their insufficiency being a failure to
include hard clipping. And my best results were from having a soft
clipper follow a hard clipper rather than precede a hard clipper.

3. Much of the sound is filtering characteristics of the loudspeaker.
Modern DSP should be capable of convoluting the signal with an impulse
response of an actual guitar amp loudspeaker (fed the impulse through an
appropriate impedance), cabinet, and even a room and microphone.

4. Part of the sound of "Marshall" amps comes from the amp's output
impedance getting fairly high during distortion. When the amp is running
clean, the output impedance is lower. Frequency response of a loudspeaker
varies with the amp's output impedance.
When attempting "Marshall" simulation (including the closed-back
cabinet) without doing anything about varying output impedance, I have
found a good approximation by using (or modeling) the loudspeaker being
fed through a resistor of value somewhat more than the loudspeaker's
nominal impedance. A "Marshall" cabinet has less bass content when fed by
a low impedance source.
This was less of a factor with open back cabinets.

5. Although simulating nonlinearities of the loudspeaker are necessary
for a totally realistic sound, I did not find this necessary for a good
sound. As part of this, I did try a tube amplifier output stage (combined
with op-amps) with ridiculously low supply voltages (as low as 12 volts)
but normal heater voltages. This does work, although maybe not always.

- Don Klipstein ([email protected])
 
E

.:: Evanescence ::.

Jan 1, 1970
0
I'm not for transistors or tubes. It sounds great on my iPod and that's
all that counts. And it has neither.

It uses little green dwarves to play the music?
I think a few dwarves can decode MP3 files.

[]s
 
E

.:: Evanescence ::.

Jan 1, 1970
0
Um vampiro chado Keith <[email protected]> aterrorizava mulheres indefesas do
grupo sci.electronics.design na data de 11 jul 2004:

Change "PROVE" to "HEAR", or perhaps "SENSE", and you have the phools
nailed.

Exact.

[Going on to Audiophool mode.]
OK, if we use XYZ-400 speakers with $400 gas-cooled RCA cables, painted
with a pink color, it proves the transistor sucks.
[Returning to normal mode...]

E., playing music in his PC' cheap speakers.
 
B

Bob Wilson

Jan 1, 1970
0
Yep. Transistor amplifiers designed to distort just like tooooob
amplifiers can't be discerned to be transistor amplifiers in blind
tests.

I find that people who like tooooob amplifiers aren't classic music
aficionados, or if they are, haven't ever been to a live concert hall.

I can spot toooob cross-mod distortion in a Mozart woodwind ensemble
at ANY output level.

Toooobs should be banned as power wasters.

Certainly some jerk is going to complain that transistor amplifiers
hard-clip. ONLY if they're poorly designed.


I suspect that may of those people who love the tube sound, like it because it
pleases their ears, not because it is better.

Bob.
 
B

Bob Wilson

Jan 1, 1970
0
Do you have any references on designing transistor amplifiers to distort
like tubes?

The rock-n-roll crowd still wants tube final amps, but they're purposely
using the tube distortion (and power supply sag, and "poor" magnetics,
etc.) as part of the music. There's been general rejection of the
obvious solution using a DSP to do the low-level processing then a
_very_ clean transistor final, but I don't know if this has to do with
psychoacoustics or psycho amplifier buyers.


It's not just the rock and roll types. The jazz blues "hammond" sound
results to a large degree from the distortion created by overdriving a
EL34 or KT66 optput pair (not to mention the spinning baffles/horns of
Don Leslie's speaker cabinet).

But there is a big difference between a "music produder" and a "music
REproducer". With the former, anything is OK, providing you get the sound
that you want. The latter, however, is supposed to only accurately
reproduce the former. You can't faithfully reproduce anything by adding
distortion!

Bob.
 
B

Ban

Jan 1, 1970
0
Jim said:
Yep. Transistor amplifiers designed to distort just like tooooob
amplifiers can't be discerned to be transistor amplifiers in blind
tests.

Any competent amplifier that is not overdriven sounds alike. Amps are
"transparent" to the program material, they just amplify. If an amp colours
the sound, it is IMHO unusable crap.
I find that people who like tooooob amplifiers aren't classic music
aficionados, or if they are, haven't ever been to a live concert hall.

I can spot toooob cross-mod distortion in a Mozart woodwind ensemble
at ANY output level.

Yes, and that is why SS equipment is found in any studio.
Toooobs should be banned as power wasters.

Today an important viewpoint. With rising energy costs tube affectionados
pay their bill for a luxury distortion box. And you pay double, cause the
A/C will have to transport all that heat outside.
Certainly some jerk is going to complain that transistor amplifiers
hard-clip. ONLY if they're poorly designed.

Well if you read that PDF from the tube-amp manufacturer, which the link
refers to, there are a few instances where a tube amp indeed might have some
advantages. In my opinion there are very few apps requiring or benefitting
from tubes:

1.) for a guitar it "enhances" the bass sound by adding 2nd harmonics that
fool the ear to hear subharmonics. The microphony will give some additional
"sustain", one reason why "combos" are so popular. Also the added higher
harmonics will bring out overtones, which give the famous "singing"
characteristic to a Gibson Les Paul.
2.) Similar with tube preamps for voice mikes, any Peter Miller with an
average voice sounds a bit like Peter Gabriel due to the added harmonics.
3.) EMP hardened equipment for military will be more rugged with tubes than
some delicate FET in the input.
4.) A microwave oven without magnetron? Or very high power transmitters.
Tubes can be made really big.


I love to drink wine too.
 
K

Kevin Aylward

Jan 1, 1970
0
Jim said:
Yep. Transistor amplifiers designed to distort just like tooooob
amplifiers can't be discerned to be transistor amplifiers in blind
tests.

Oh?....

Your obviously not a guitarist.

Show me a tube simulator that measures essentially the same as a tube
amp does.

Look dude, tube guitar amps and tube hi-fi amps are totally different. A
tube guitar amp set "clean" sounds cleaner then a transistor amp.
Distortion can actually make things sound clearer.

Sure, in principle, one may be able to make a transistor guitar amp
sound like a tube amp but, to my satisfaction, no one does. There are
too many details. For example, a tube amp has enormous overload
capability on its input stage, e.g. 300v anode verses 15V.

Take any typical commercial transistor guitar amp, and compare it with
any typical tube guitar amp, and its distortion characteristics are
totally different, and they *measure* way different. We are not debating
"golden ears" here or what may be the case in an ideal world.
I find that people who like tooooob amplifiers aren't classic music
aficionados,

Irrelevant. I don't play classical music through my fender twin.
or if they are, haven't ever been to a live concert hall.

I can spot toooob cross-mod distortion in a Mozart woodwind ensemble
at ANY output level.

A high performance hi-fi tube amp won't have any audible distortion. It
will also sound exactly like a transistor one.
Toooobs should be banned as power wasters.

Certainly some jerk is going to complain that transistor amplifiers
hard-clip.

They do, in general.
ONLY if they're poorly designed.

Nonsense. A guitar amp using conventional circuitry, i.e. op-amps, will
hard clip. One needs to take extra steps to avoid hard clipping. Of
course, some pro power amps have VCA limiters, but not using them, does
not make them a poor design.

Kevin Aylward
[email protected]
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
K

Kevin Aylward

Jan 1, 1970
0
Jim said:
Psycho says it all ;-)

I think you can come pretty close to toooob distortion with
diode-soft-limiters in the front-end.

Ho hummm...you think wrong. Tried to death 20+ years ago. Don't work.
Its not just clipping that makes the sound.

Stick with what you actually *know* about Jim. Unfortunately, being an
expert in transistor level detailed design, don't say much for your
hearing ability, which, at your age, is somewhat dubious.

Kevin Aylward
[email protected]
http://www.anasoft.co.uk
SuperSpice, a very affordable Mixed-Mode
Windows Simulator with Schematic Capture,
Waveform Display, FFT's and Filter Design.
 
J

John Woodgate

Jan 1, 1970
0
I read in sci.electronics.design that Kevin Aylward
lueyonder.co.uk>) about 'Slashdot - Tubes vs Transistors', on Mon, 12
Jul 2004:
For example, a tube amp has enormous overload
capability on its input stage, e.g. 300v anode verses 15V.

Quite right (well, almost). If you look at the waveform from a guitar
pickup, you find an enormous initial transient, maybe ten times the
amplitude of the ensuing signal, which is hardly surprising when you
think of what happens to the deflection of a plucked string.

It isn't just a high anode supply voltage at the input stage that's
required. You have to look at what happens all the way through the
amplifier to that big transient, because as soon as any stage clips
momentarily, the forward gain drops to zero, there is no overall
negative feedback any more and the input stage (or whichever stage
receives the feedback signal) immediately goes into gross overload.

I found this out when trying to use a hi-fi power amp design (with
tooooooooobes) as a guitar amp. Hurried mods to input stage were
required! Now people are finding the same effect with modern
microphones: transient peak output voltages of over 1 V are being
measured, and many mixer input stages won't cope.
 
M

Mr TUBEAMPS

Jan 1, 1970
0
banning tubes what crap.
theres nothing wrong with tube amps, some make
good room heaters like fan cooled ones.
i use a marshall 9200 2/ch 100rms p/ch, fantastic.
 
I

Ian Stirling

Jan 1, 1970
0
..:: Evanescence ::. said:
It uses little green dwarves to play the music?
I think a few dwarves can decode MP3 files.

Idly wondering how many computors it'd take to decode an MP3 file.
I suppose the final output could be done with an edison cylinder,
a micrometer screw, and a lot of time.
 
Top