Tube sound with op amps?

[Tolu]

Is it possible to get tube sound out of op amp based preamplifier?

I like the sound of tubes (esp. EL34) and I am asking myself if it is possible to get the warm and lovely sound of tubes by using opamps (in a perhaps strange way) in a preamp that simulates good tubes.

[analog_sa]

Of course it is possible. Opamps have been designed as direct sonic replacements for tubes. There are some obvious substitutes like 5534 for EL34 and OPA604 for RE604. Others you will have to discover yourself once you make an 8-pin to octal adapter. Or you can get one from Brown dog.

[Mr. Triatic]

You will get a rich sound from a OPA2134 at approximately 38mA with B+ 350V, although the chip will have a short lifespan.

Seriously no, there's no chance in hell you will get "tubesound" from just opamps, DSP is the way to go, but i would say that it is easier and less expensive to use real tubes, like a tube buffer or preamp.

[Bidoux]

I think you can have some kind of "tubey sound" with this one but I have no idea why !

the (c)

[Mesa]

Sansamp makes quality 'tubish' overdrive effects for guitar and bass with cascaded opamps, but for music amplification it just won't happen. Try for a tube preamp and mosfets or very high quality chips for the power amp. That's as close as you'll get.

[dhaen]

Originally Posted by Mr. Triatic

You will get a rich sound from a OPA2134 at approximately 38mA with B+ 350V, although the chip will have a short lifespan.
.........

Absolutely brilliant although I think that more than 38mA would be drawn!

Seriously speaking, I think that accurately synthesising valve/tube sound with s.s will probably be more complex than using the real thing.

[spkr guy]

As far as getting tube sound from an solid state op amp, well tubes are voltage devices and solid state is a current device . They drive speakers differently so you might get close but two different animals

Frank

[Piercarlo]

Originally Posted by Tolu

Is it possible to get tube sound out of op amp based preamplifier?

I like the sound of tubes (esp. EL34) and I am asking myself if it is possible to get the warm and lovely sound of tubes by using opamps (in a perhaps strange way) in a preamp that simulates good tubes.

Possible is possible. But you need to obtain before some hints about WHAT "tube sound" you want obtain. You want a preamplifier tube sound or a power amplifier tube sound?
However at least one kind of "tube behviour" (that of triodes, i.d. the most appreciable from tubes) is not really replicable with solid state devices. This not because triodes distort mainly of even harmonic (is not this a really important matter, especially in multistage circuits) but because their combination of natural low voltage gain, relatively low intrinsic output impedance and last but not least their unique output curves (what, differently from other devices that are mainly voltage controlled current generators, are those of a true voltage amplifier, with voltage output DIRECTLY controlled by input control voltage) what, for being really reproduced, require somewhat similar to a variable threshold diode, not available in any kind of active devices except by triode itself. Neither JFETs output curves working in their so called "triode region" have nothing to share with triode's output curves. And this is an irreducible important difference.

Hi
Piercarlo

[Piercarlo]

Originally Posted by spkr guy

As far as getting tube sound from an solid state op amp, well tubes are voltage devices and solid state is a current device . They drive speakers differently so you might get close but two different animals

Frank

In actual power amplifiers are not these differences that really count. The single most important difference among vacuum and solid state power amplifiers is their totally different scale of working current.
In tube amplifiers heavy output currents are originated (WHEN NEEDED) only in the secondary of output transformers. Other big circulating current are just for heaters that, usually, route their own way just directly from main supply transformer, with almost nothing to share with other currents working in circuit.

In solid state amplifiers instead high output currents, being supplied directly from output stages without intermediaries, are inestricably mixed (and usually very BADLY mixed) with signal stage currents in a single common supply circuits starting directly from the same rectifier and the same bunch of reservoirs. And this, regrettably, is not only a "philosophical" difference but a physical one with heavy, not welcomed and often hardly to manage consequences.

Hi
Piercarlo

[kenpeter]

Can one emulate the behavior of a tube with an op-amp?
Sure, but there is gonna be an FET in there somewhere.
And you don't need an op-amp at all, though having one
in the loop for the right reasons probably woudn't hurt..

O.H.Schade (RCA Beam Power Tubes 1938) is the required
reading before embarking upon this journey. Once you grock
Schade, abusing sand to emulate triode curves at the lower
frequencies becomes easy.

But these circuits almost always have less bandwidth and
drastically lower input impedance than a real tube. And a
great deal of a "tube sound" is really "output transformer
sound", so go figure...