Vacuum Tube Modeling Package Vol. 1. Examples (Electronic edition)

Transcription

1 Vacuum Tube Modeling Package Vol. 1 Examples (Electronic edition) EXCEM Characteristics of our EL34 pentode model EXCEM 12, Chemin des Hauts de Clairefontaine Maule - France tel web site: fax Document A fichier tram36 examples.wpd page 1

2 Vacuum Tube Modeling Package Vol. 1 Examples (electronic edition) Edited and published by EXCEM S.A.. Editeur et imprimeur : EXCEM S.A. Original edition : EXCEM, 1995 ISBN Electronic Edition : EXCEM, 2000 All rights reserved. No part of this work covered by the copyright hereon may be reproduced or used in any form or by any means - graphic, electronic, or mechanical, including photocopying, recording, taping, or information storage and retrieval systems - without the written permission of the publisher. The present work is contained in the Adobe Acrobat examples.pdf file. Downloading the examples.pdf file from the web site or from the web site, storing this file on a single computer and printing this file on paper is permitted, provided the said stored file and/or the said printed document are only used for the private usage of the person who dowloaded the examples.pdf file. INTUSOFT, ICAP/4, ICAP/4DOS, ICAP/4Windows are trademarks of Intusoft, 222 West Sixth street, Suite 1070, SAN PEDRO, CA 90731, U.S.A. EXCEM 12, Chemin des Hauts de Clairefontaine MAULE FRANCE Document A page 2

3 Vacuum Tube Modeling Package Vol. 1 Examples (Electronic edition) EXCEM Table of Contents 1. Introduction Description of the sample circuits and test circuits Presentation of the five sample circuits The ALIM.CIR sample circuit The RIAA.CIR sample circuit The SERIAL.CIR sample circuit The WILLIAMSON.CIR sample circuit The OSCBF.CIR sample circuit Vacuum tube test circuits Schematics and plots...6 Document A page 3

4 1. Introduction The present document shows examples of software simulation of electronic circuits with vacuum tubes. It illustrates the capabilities of simulation of real circuits. The circuits for these examples are described in the various files contained in the tubes_13\circuits subdirectory created by the tube_13.zip file, using the models contained in the Lampe.lib library stored in the tubes_13\models subdirectory. The simulation itself was performed with an ICAP/4 Windows SPICE simulator. We have tested the library on several versions of this simulator up to version 7.6. Please refer to the Vacuum Tube Modeling Package Vol. 1 User s guide contained in the usergui5.pdf file for more information on SPICE tube models and SPICE electronic simulation. The Document A page 4

5 2. Description of the sample circuits and test circuits 2.1 Presentation of the five sample circuits The present electronic edition of the Vacuum Tube Modeling Package Vol. 1 contains five sample circuits. The first three circuits are Mr. Rydel's own brew : ALIM.CIR is an hydride (bipolar transistor/vacuum tube regulated power supply, RIAA.CIR is an RIAA preamplifer with direct coupling and without global feed-back, SERIAL.CIR is a power audio amplifier with serial output stage using Russian 6C33-B power triodes. The fourth sample circuit, WILLIAMSON.CIR, is the well known Williamson amplifier, in its second embodiment as published in Wireless World in 1949 [13]. The fifth and last circuit, OSCBF.CIR is an amplitude stabilized low frequency oscillator used in a Philips millivoltmeter. 2.2 The ALIM.CIR sample circuit This power supply (see schematic on page 7) is based on a triode mounted EL34 pentode, implemented as a series regulator ballast. The ECC83 is a differential amplifier comparing the voltage across the D1 zener diode, and the shifted and divided output voltage. The original part of the circuit is a cascode mounted NPN transistor, substantially increasing the open-loop gain of the regulator. As the simulation demonstrates (not shown), the regulated output is pretty clean : the input ripple of about 18 V peak to peak is reduced to an output voltage of about 50 mv peak to peak. The ripple attenuation is about 51 db. 2.3 The RIAA.CIR sample circuit The RIAA preamplifier schematic is shown on page 8, with an anti-riaa circuit R17-R18-C13- C14 connected at its input. This configuration allows the control of the accuracy of the RIAA fitting (though a more rigorous approach would necessitate the addition of a unity gain voltage controlled voltage source). The figure on page 9 shows that RIAA compliance is better than 1 db between 20 Hz and 70 khz. The pentode in the preamplifier front-end is intentionally biased with a low anode voltage. It provides enough gain to compensate the noise produced by the R9-R10-C3-C11 RIAA circuit. The double triode output stage has a direct link to the anode of the front stage pentode, and a feed-back circuit R11-R16 that provides a low output impedance. 2.4 The SERIAL.CIR sample circuit The serial amplifier shown on page 10 does not use any output transformer. It looks more like the kind of circuit that are implemented with two NPN output transistors. This low-cost version provides 24 W to a 32 6 loudspeaker system. If eight output tubes had been used, a power of 100 W would be available, with a reduced bandwidth. The high voltage section of the driver stage is bootstraped (C3, Document A page 5

6 1 µf) for increased linearity. The plot on the top of page 11 shows the harmonic distortion for an output power of 24 W at 1 khz. H2 is at 44 db and H3 at 42 db. The C9 capacitor in the feed-back circuit provides a 7.8 µs rise time as shown on the bottom plot of page The WILLIAMS.CIR sample circuit Williamson designed the first truly High Fidelity audio amplifier. Most of all, he clearly understood the causes of the lack of performance of previous designs. It is very interesting to simulate this amplifier and compare simulation results with Williamson's values. The simulated circuit appears on page 12. Let us note that the output transformer was modeled with Williamson's data for the leakage inductance and the resistance of the windings. We used a load. The output power does not exceed 14 W without clamping. We used a 4 µf decoupling capacitors instead of the 8 µf in Williamson's circuit, without significant effect. The plots on page 13 show : the amplifier frequency response without input capacitor (curve 1), with a 50 nf C6 input capacitor (curve 2) and the open loop gain (curve 3). The feed-back ratio appears to be 17 db. Curves 2 is in agreement with Williamson's results, even though his schematic does not include an input capacitor. Did he used that capacitor? The harmonic distorsion analysis of the Williamson amplifier is shown on page The OSCBF.CIR sample circuit This circuit shown at top of page 15 comes from the schematic of the Philips GM6012 millivoltmeter. This oscillator deserves interest for its amplitude regulation circuitry. The transient analysis of the starting of oscillation can be studied if one simulates this circuit (not shown). 2.7 Vacuum tube test circuits Two test circuits are provided in the Vacuum Tube Modeling Package vol. 1. TESTRIO.CIR is intended for the testing of triodes, and TESTETRO.CIR for the testing of tetrodes and pentodes. If you want to test a tube, just insert the tube model's name, and select the appropriate grid voltage and anode voltage steps. You will obtain the tube characteristics. You will be able to check that our models are in excellent agreement with manufacturer's data. 2.8 Schematics and plots The next pages show the schematics and plots mentionned above. Document A page 6

7 R5 47K X1 EL34 R1 220K V(13) X2 EMETT ECC83 D1 BZX79A47 R2 47K R3 43K R4 10K X4 GZ34 C1 10U R7 5K K V2 SIN R8 100 R9 100 C3 50U R11 4.7K D3 BZX79A47 D2 BZX79A47 V(2) CAPA V(15) OUT

8 R3 2.2K R6 1MEG V1 AC R9 220K C3 12N R10 27K X3 V6DJ8 R11 100K X4 V6DJ8 R12 3.3K R13 47K R14 1MEG C5 1U R15 100K C6.1U C7 2.2U R16 4.7K V(16) V2 SIN C11 3.9N X5 EF86 C12 47N R17 75K R18 887K C13 1N C14 3.6N R19 1K V(11) IN V(3) VAL V3 300V C15 2.2U

9 Document A 9 page 9

10 X1 V6C33C-B X2 V6C33C-B X3 ECC81 C1.1U C2.15U R8.47MEG C3 470U RLOAD 32 V(13) OUT V3 PULSE R12 500K X5 ECC81 R14 200K R15 220K V4 250V R16 1K R18 10K C4 1U C5 1U R19 100K X7 ECC83 R20 1K R21 330K R22 470K R23 470K R24 100K C6.1U V5 300V V(8) GB V(4) GH V6-45 I(V7) IPLATE V(14) BOOTS R26 1 R C8 100U R28 82K C9 10P

11 Document A 11 page 11

12 V1 450 R4 1K R5 1K R6 100K R7 100K C1.25U C2.25U R8 47K R9 47K X3 V6SN7GTB X4 V6SN7GTB V2 450 R R11 470K R12 470K C3 50N C4 50N X5 V6SN7GTB R13 22K R14 22K R15 22K C5 8U X6 V6SN7GTB R16 33K R17 47K R19 1MEG C6 50N V3 AC C7 8U R C8 200P V(17) OUT V(14) PLATEDEP V(20) CATDEPH V(12) DRIVERL V(11) DRIVERH R R L4 11MH L5 11MH R L6 100H L7 100H R R R29.34 C9 400PF C10 400P R K R K X12 KT66TR X13 KT66TR L9 11MH L10 11M C12 100P C13 100P R

13 Document A 13 page 13

14 Document A 14 page 14

15 V(8) R9 390K R8 56K R6 33K V1 PULSE C6 47N X2 V6DJ8 C5 220N V2 85V R1 33K V(1) PLATE R2 1K R3 390K R7 2MEG C3.47U C4 1.5N C1 150P R4 120K V(5) FILTER C2 560P R5 39K