HP Aikido Stereo 9-Pin PCB User Manual

Aikido Stereo 9-Pin PCB

Revision C

USER GUIDE

Introduction Overview Schematics Recommended Configurations Tube Lists Assembly Instructions

05/29/2008

GlassWare

AUDIO DESIGN

GlassWare Audio Design

voltage power supply; thus, a real shock hazard exists.

Once the power supply is attached, be cautious at all times. In fact, always assume

disconnected or shut down. If you are not an experienced electrical practitioner,

plus voltage have someone who is experienced review your

loving solder slingers left; we cannot afford to lose any

PCB is extra thick, 0.094 inches (inserting and pulling tubes from their sockets won’t

per traces, and

stage amplifiers;

thus, one board is all that is needed for stereo unbalanced use or one board for one

s, with

eight mounting holes, which help to prevent excessive PCB bending while inserting

spaced solder pads

foil

film resistors, for example). In addition, most capacitor

sized coupling

The boards hold two coupling capacitors, each finding

its own 1M resistor to ground. Why? The idea here is that you can select (via a rotary

citors in parallel. Why again? One coupling

slug

tantalum…. As they used to sing in a candy bar commercial: “Sometimes you feel like

capacitor has its virtues and failings. So use the one that best suits the

music; for example, one type of coupling capacitors for old Frank Sinatra recordings

valued capacitor would set

frequency cutoff of 80Hz for background or late night listening; the other

could

be hardwired together on the PCBs via jumpers J8 and J9, one smaller one acting as a

This PCB is for use with a high-

that capacitors will have retained their charge even after the power supply

before applying the Bwork. There are too few tubemore.

Warning!

Rev. C Overview

Thank you for your purchase of the TCJ Aikido 9-pin stereo Rev. C PCB. This FR-

bend or break this board), double-sided, with plated-through 2oz cop the boards are made in the USA. Each PCB holds two Aikido line-

channel of balanced amplification. The boards are four inches by ten inche

and pulling tubes from their sockets.

PCB Features

Redundant Solder Pads This board holds two sets of differentlyfor each critical resistor, so that radial and axial resistors can easily be used (bulkresistors and carbonlocations find many redundant solder pads, so wildly differingcapacitors can be placed neatly on the board, without excessively bending their leads.

Dual Coupling Capacitors

switch) between C1 or C2 or both capa capacitor can be Teflon and the other oil or polypropylene or bee’s wax or wet-

a nut; sometimes you don't.”

Each type of

and the other for Beethoven string quartets.

Or the same flavor capacitor can fill both spots: one lowera lowhigher-valued capacitor, 5Hz for full range listening.

Or if you have found the perfect type of coupling capacitor, the two capacitors

bypass capacitor for the lager coupling capacitor.

amplifier delivers the sonic goods. It offers low distortion, low output

lies in its internal symmetry,

whic

circuit works

resistor,

, complementary, balancing

f the eyes were

perfect, then perfectly flat (perfectly linear) lenses would be needed, whereas imperfect

loading a

age and idle current

works well to flatten the transfer curve out of the

Although they

would never fit on the printed circuit board (PCBs), 211 and 845 triodes could be used

or any other

, not the tubes that make the Aikido

any believe that a different triode equals a different topology; it

f being a

The Aikido circuit sidesteps power supply noise by incorporating the noise into its

normal operation. The improved PSRR advantage is important, for it greatly unburdens

king or tube selecting, you should easily be able to get a

cathode amplifier with the same tubes

6dB PSRR); with some tweaking of resistor R15’s value,

ditionally, unless regulated power supplies are used for

the plate and heater, these critical voltages will vary at the whim of the power company

and your house’s and neighbors’ house’s use, usually throwing the once fixed voltage

rtheless, the Aikido amplifier will still function flawlessly, as it

GlassWare Audio Design

Introduction to the Aikido

The Aikido impedance, a great PSRR figure, and feedback-free amplification. The secret to it superb performance— in spite not using global feedback—

h balances imperfections with imperfections. As a result, the Aikido

at least a magnitude better than the equivalent SRPP or grounded-cathode amplifier.

For example, the Aikido circuit produces far less distortion than comparable circuits using the triode’s own nonlinearity against itself. The triode is not as linear as a so ideally, it should not see a linear load, but a corresponding non-linear load. An analogy is found in someone needing eyeglasses; i

eyes need counterbalancing lenses (non-linear lenses) to see straight. Now, triode with the same triode— under the same cathode-to-plate volt and with the same cathode resistor— amplifier.

B+

6922 6922

Rgs

R15

out

69226922

R16

Aikido Amplifier

In the schematic above, the triodes are so specified for example only.

to make an Aikido amplifier. The circuit does not rely on 6922 triodes specific triodes to work correctly. It’s the topology special. (Far too m doesn't. Making this mistake would be like thinking that the essential aspect o seeing- eye dog rested in being a Golden Lab.)

the power-supply. With no twea

-30dB PSRR figure (a conventional groundedand current draw yields only a -

-60dB or more is possible. Ad

relationships askew. Neve tracks these voltage changes symmetrically.

they

wear out. Just as a tire’s weight and diameter decrease over time, so too the tube’s

conductance. So the fresh 6DJ8 is not the same as that same 6DJ8 after 2,000 hours of

which they are inclined to do,

—

the Aikido amplifier will always bias up correctly, splitting the B+ voltage between the

triodes. Moreover, the Aikido amplifier does not make huge popping swings at start

up, as the output does not start at the B+ and then swing down a hundred or so volts

when the tube heats up, as it does in a ground

supply noise from the output, by injecting the same

tube cathode follower circuit.

The way it works is that the input stage (the first two triodes) define a voltage divider

the PS noise is presented to the CF's grid; at the same time the

100k resistors also define a voltage divider of 50%, so the bottom triode's grid also

sees 50% of the PS noise. Since both of these signals are equal in amplitude and phase,

other out, as each triodes sees an identical increase in plate current

If the output connection is taken from the output cathode follower's cathode, then the

true if the cathode follower's cathode resistor

is removed. (Besides, this resistor actually makes for a better sounding cathode

follower, as it linearizes the cathode follower at the expense of a higher output

should

ohms for example. When used

o cathode resistor bypass capacitors should be used, as these

y few do not damage the sound,

How do I wire up a rotary switch for switching between the two coupling

position switch and some hookup wire. All

four coupling capacitors attach to the input contacts and the two channels of output

coupling capacitors C1’s or C2’s or both capacitors’ outputs. The

drawing below shows the knob on the faceplate and the rotary switch from behind.

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Remember, tubes are not yardsticks that never change, being more like car tires—

use. But as long as the two triodes age in the same way— as they do the same amount of work and share the same materials and environment

-cathode amplifier.

This circuit eliminates poweramount of PS noise at the top and bottom of the two-

of 50%, so that 50% of

they cancel each (imagine two equally strong men in a tug of war contest).

balance will be broken. The same holds

impedance. Unfortunately, it should be removed and the bypass capacitor C3 be used when driving low- impedance headphones, 32as a line stage amplifier, n capacitors are very much in the signal path and ver unless high quality capacitors are used.)

capacitors? We need a four- pole, three-

can receive either

(The switch is shown on the "C1 + C2" position.)

Right Output

Lt C2

Lt C1

Rt C1

Switch Rear

Rt C2

C1 & C2

Switch Front

Left Output

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