Todo lo que debes saber sobre las válvulas y no te atreves a preguntar

[jbl-fan 260]

Hola estimado escultor, me pilló el carnet parece.  Un resfrío mal cuidado se me complicó y estoy con toneladas de medicamentos y con licencia médica:  tamiflu, azitromicina, oxolamina y salbutamol, aparte del tapsin... y con tinitus !!  No podré ir a compartir los 300B con ustedes a tu departamento, mis virus y bacterias de la vía respiratoria ne tienen muy ocupado.  Cuando me recupere de esta gripe con bronquitis hablamos.  Saludos cordiales y muuuuuchas gracias por tu generosidad audiófila.  Un abrazo.  Saludos audiófilos.

[MartinV56 866]

Mcintosch Lab circa 1960

[seixip 12]

Ni Push-Pull, ni Single-Ended....lo dejo para que opinen los que saben

http://www.vacuumstate.com/fileupload/dpa300B_brochure_lo_rez.pdf

PD: Si no corresponde a este hilo, favor cambiar

Editado July 13, 2016 at 17:57 por seixip

[MartinV56 866]

hace 1 hora, seixip dijo:

Ni Push-Pull, ni Single-Ended....lo dejo para que opinen los que saben

http://www.vacuumstate.com/fileupload/dpa300B_brochure_lo_rez.pdf

PD: Si no corresponde a este hilo, favor cambiar

Diferencial, primeros watts trabaja clase A, le das polenta y pasa a trabajar AB

[Patagonia 739]

On ‎12‎-‎07‎-‎2016 at 18:30, jbl-fan dijo:

Hola estimado escultor, me pilló el carnet parece.  Un resfrío mal cuidado se me complicó y estoy con toneladas de medicamentos y con licencia médica:  tamiflu, azitromicina, oxolamina y salbutamol, aparte del tapsin... y con tinitus !!  No podré ir a compartir los 300B con ustedes a tu departamento, mis virus y bacterias de la vía respiratoria ne tienen muy ocupado.  Cuando me recupere de esta gripe con bronquitis hablamos.  Saludos cordiales y muuuuuchas gracias por tu generosidad audiófila.  Un abrazo.  Saludos audiófilos.

bueno, entonces quedó para más adelante supongo?...

[jbl-fan 260]

Síiii... una vez que salga de este cocktail de remedios y si llego a agosto....  (buahhhh)... al menos voy a morir lleno de buena música.... No se hagan ilusiones, me llevaré mis amplificadores al más allá...

[escultor 130]

Ya pasara´ y habra´ tiempo para jugosear 

[seixip 12]

Diferencial, primeros watts trabaja clase A, le das polenta y pasa a trabajar AB

Pero el diseñador clama que esta es una topología nunca antes usada salvo en alemania para reactores nucleares...es verdad o marketing?

[MartinV56 866]

hace 22 minutos, seixip dijo:

Pero el diseñador clama que esta es una topología nunca antes usada salvo en alemania para reactores nucleares...es verdad o marketing?

Sigamos analizando, pero en principio parece un diferencial.

[escultor 130]

Lo diferente es que aplica  diferencial en todas las etapas 

[MartinV56 866]

http://www.keith-snook.info/index.html

 

[MartinV56 866]

Valves versus Transistors

http://www.keith-snook.info/valves-versus-transistors.html

[MartinV56 866]

 

JBL Amplifier System 1959-60 20+40 Watt with active crossover

JBL PL-100 (1959-1960) amplificador valvular diseño de Henry Wolcott amplificador para las Hartsfield  uno de los primeros diseños para parlantes activos.

 

https://sites.google.com/site/jblpl100/

AUDIO TECHNICAL WHITE PAPER:
A FUNDIMENTALLY NEW TOPOLOGY FOR AUDIO FREQUENCY POWER AMPLIFICATION
By Henry Wolcott

Introduction :
This paper is directed to those who purchase or represent perfectionist"high end"
audio amplifiers. Our aim here is two-fold. To present a significant new technology and
to discuss that technology in the contest of high fidelity amplifier design as it has been
practiced to date. Naturally, we hope that your reading of this document will persuade
you to look favorably on our product, but we also trust you will obtain useful factual
information on significant issues in amplifier design-information that is not readily
available in cumulative form elsewhere. We attempted to present engineering
concepts in plain English insofar as possible and we hope that in some small way this paper
contributes to a wider understanding of the fundamental principles and constraints of
Audio amplifier circuit design.

Reinvigorating a Stagnant Technology
The basic design of both solid state and vacuum tube audio power amplifiers can
be said to be mature. No significant innovations in circuit topology have been developed
within the last ten years and the current art in amplifier design would appear to have
exhausted the possibilities of basic analog circuit configuration. For the perfectionist
user, this state of affairs cannot but be distressing because no extant design in the
marketplace approaches the ideal.
Our firm is introducing an amplifier topology without close precedent, the first
radically innovative design to appear in more than a decade in either the solid state or
vacuum tube categories. We believe it is demonstrably better than established topologies
across a broad range of performance parameters, in other words, better in virtually
every way.
The circuit described in this paper is certainly unique, but is new only in the sense
of being new to consumer electronics and in having been recently revised to make use of
modern component types and manufacturing processes. The basic circuit was actually
developed in the early sixties and the designer was granted two U.S. patents at that
time. Nevertheless, the topology is entirely unprecedented in high fidelity applications
In addition, represents a highly significant development in this area.
Before we discuss the specifics of the design, we would like to express a position
that needs restating in the high-end audio marketplace where we are attempting to
promote our product. We believe circuit topology is the main determinant in amplifier
performance and the preoccupations of many contemporary designers with resister
and capacitor types and even interconnect wiring is misguided and is, we think, indicative
of the general paucity of real design innovation prevailing in the high end today.
We certainly dont maintain the quality of passive components is un-important, but beyond a
certain minimum level of parts tolerance, component quality is secondary to circuit
topology in the ultimate determination of system performance. Thus we view the
common high end practice of constructing flawed circuits out of exotic capacitors and
resistors as distinctly unpromising and altogether unlikely to overcome the limitations of
such circuits or to advance the art of amplifier design in any significant way. We would
further suggest the truth of our position can easily be demonstrated in listening tests and
in bench measurements.

Why Vacuum Tubes

From the time our basic topology was developed some thirty years ago to the present,
enormous progress has been made in the design of solid state amplifiers and in
the formulation of solid state devices themselves. Due to the improvements in transistor
design, coupled with the inherently lower maintenance requirements of solid state gear,
most designers aiming to create a highly accurate as opposed to a euphonic amplifier
Circuits have opted for transistors. We have not and we would like to explain
why. Both solid state and tube amplifying circuits are highly problematic and both
present the design engineer with formidable challenges. Challenges that are well worth
examining. The fundamental design limitations facing the solid state engineer remain the
limitations of the devices themselves, resulting in many distortion mechanisms,
inherently low power bandwidth, temperature instability and hard clipping characteristics.
The fundamental limitations facing the vacuum tube designer are more various,
lying in the high output impedance of the devices and lack of complementary forms, the
disadvantageous relationship between gain and linearity, the gross frequency limitations
of the coupling transformers required at output and of course the high cost, inefficiency
and high heat output inherent in vacuum tubes themselves. Perhaps rather surprisingly,
we found the limitations of vacuum tubes to be less intractable. In other words, at this
late date, it is still possible to build a better power amplifier with the archaic vacuum tube
than with the very latest solid state devices. The following sections indicate just how we
have arrived at this conclusion.

[MartinV56 866]

Wolcott audio Presence EL34 amp

http://www.wolcottaudio.com/WA_presence.htm

[MartinV56 866]

The Tube Amplifier
Dick Ohlser

After nearly a century of evolution it is safe to say that vacuum tube circuitry has reached a state of maturity. It appears that every conceivable circuit nuance has already been investigated; no stone left unturned by a host of ingenious engineers who grew up knee-deep in vacuum tube technology. For example, even 1952 Radiotron Designer Handbook (4th Edition) already contains over 1,400 pages of information about radio receiver and audio amplifier design and application.
The resultant legacy from the golden age of audio is enormous in scope and magnitude.
It is therefore not surprising to recognize most modern high-end power amps for what they really are: recycled 50s designs with inferior output transformers. The only thing original about these products is the cosmetics. The associated advertising hype tends to deflect attention away from the essence of the circuitry and instead focuses on familiar audiophile esoterica such as wonder caps, kryptonite resistors, and magic wire. The bottom line for the consumer is often a price tag equivalent to the cost of a new car for an amp that isnt even as sophisticated (or good sounding) as a vintage Harman Kardon Citation II.
This power amplifier breaks new ground in audio electronics, but as the constructor, will tell you, its basic topology is over 40 years old,and having been used in amplifier systems he designed for JBL in 1960(PL-100). It earned him two US patents at the time. His US and foreign patent total today in instrumentation and audio design stands at an even dozen. After founding in 1961, a precision instrumentation company with sales to aerospace companies and national laboratories, he further refined the original design as a serie instrumentation amp. They was designed as a lab-grade instrument for precision calibration and testing. Over 1,100 units were sold worldwide, including six systems at the U.S. Bureau of Standards, now NIST. This new amplifier he manufacture today is the latest descendant of the original circuitry, introduced under the WA company banner in 1988. It represents a third generation version of the original design, optimized expressly to meet the needs of the high-end and professional audio markets. While each building block of the amplifier is not necessarily new, the sum total of its design elements represents an original and unique statement in the realm of hi-fi design.
I only plan to provide a few general and technical comments to give an overall feel for the the amp.
They believes that circuit topology is the primary determinant in amplifier performance. He finds traditional designs to suffer form several obvious failings resulting directly from the limitations and distortions inherent in transformer coupled output stages. Better load tolerance, greater stability, lower static distortion and output impedance, better transient behavior with lower noise, and higher power supply rejection are the stated performance objectives of the circuits.
The amps is fully balanced at all stages beyond the input stage. A major feature is the use of balanced positive (feedforward) as well as negative feedback, which allows the cancellation of the amps internal impedance. A control on the panel lets the user adjust the output impedance at frequencies below 1000 Hz from about two ohms to zero, and even about 0.5 ohm negative. Zero output impedance yields an infinite damping factor, while moving into negative territory cancels the effect of cable resistance and even some of the voice coils DC resistance.
Thus, the amp is intimately coupled to the load and is able to control transient behavior to a degree impossible with traditional designs.
A pair of 6922 dual triodes makes up the input stage. Each 6922 is configured as a White cathode follower, and the two followers are connected in parallel to create a buffer stage of high input impedance, low output impedance, and exceptionally low distortion. Negative feedback is applied to the second cathode follower from a tertiary winding in the output transformer. A pair of 6GW8 triode/pentodes makes up the second and third stages of the amp providing voltage gain and symmetrical drive signal. The pentode halves are operated as cathode followers with transistor current sources and are directly coupled to the output stage. The output stage is comprised of eight EL34 pentodes operated as pure pentodes in a conventional push-pull circuit. The output tube screen girds are actively regulated. My review samples incorporate the latest wide bandwidth output transformers with exceptionally low leakage inductance and only moderate winding capacitance. Their full power bandwidth is 20 Hz to 30 kHz, running flat out at 220 wpc into 4 ohms. These trannies feature a tertiary feedback winding (ala McIntosh#8217;s unity coupled output stage) closely coupled to the primary. This isolates the feedback loop from load fluctuations and ensures that that full error correction is provided even in the presence of highly reactive loads.

[MartinV56 866]

JBL PL-100 amp

http://www.hififorum.nu/forum/topic.asp?TOPIC_ID=83673

[MartinV56 866]

Un JBL PL 100 amp modernizado

http://www.positive-feedback.com/Issue25/wolcott_p280.htm

 

[MartinV56 866]

[MartinV56 866]

[matador 97]

On 25. august 2016 at 21:23, MartinV56 dijo:

Jajajaja.... Abusibo con los que son más chiquitos de tamaño :)