TEST EQUIPMENT

This is what I use in my lab on a daily basis. They are the essential pieces of test gear necessary to operate as a safe and reputable repair facility for tube and solid state audio. All of these pieces have been restored electronically/mechanically and are period correct.

TEKTRONIX 434 Storage Oscilloscope (1975)

This “Tek” serves as my main scope and is a reliable daily driver. It is an analog storage scope that has a bandwidth of 24 MHz and uses a tunnel diode in its trigger circuit. The storage is done in the CRT itself, by trapping charge on a special fine grid of isolated pads behind the phosphor where the electron beam is then blocked or released.

RCA WA-504A Sine/Square Wave Generator (1980)

This is my main wave generator and is highly accurate. The instrument features true analog tuning (variable capacitance) frequency adjustment. Newer audio generators are digital synthesized and generate unwanted noise. This is one of my few pieces of test gear that is Solid State - It was modded to have banana jacks and the indicator lamp was moved to provide space. Much better than the original hardwired alligator clips.

SUPERIOR ELECTRIC “Powerstat” Variac (1969)

This gets used every day for powering up any amp thats gets brought to me and for testing amps that I have recently worked on. It provides a safe and soft start to any build, allowing me not to blow transformers and tubes because of a short or faulty wiring. It is useful as well to compare how an amp operates at modern wall voltage of 120vac to vintage wall voltage of 110-115vac. Essential, and far higher quality than the cheap imported Variacs you can get online today. This thing can handle a whopping 10A on its windings without issue.

KNIGHT 83Y135 Signal Tracer (1956)

I don’t have to use this all the time, but when I do - it’s kind of a secret weapon when tough to diagnose and intermittent problems arise. There are certain issues that can only be heard and this allows me to tap into any part of a high voltage circuit and hear stage by stage what is happening. The needle probe is completely new/rebuilt to original spec and the whole thing was re-capped, new tubes, and the enclosure was re-painted.

HEATHKIT Model IT-11 Capacitor Checker (1965)

This allows measurement of leakage on all types of capacitors at full voltage rating (Up to 600+VDC). It also allows measurement of caps, resistors, inductors and can determine the turns ratio of unknown transformers. The “Power Factor” control allows ESR to be calculated on Electrolytic Caps - a neat ability included by Heathkit. The leakage testing is the main function for me - something that there is no modern equivalent of that is readily available. This unit was re-capped, new tubes installed and factory calibrated.

WEBER “Tru-Load” Dummy Loads (2016)

These dummy loads are indispensable for amp biasing and troubleshooting. It’s simply not possible to work on tube equipment without them. They are rated for 200 Watts continuous/400 watts Peak each. These are not just resistive loads like many cheap load box’s are - They are reactive loads that have an actual speaker motor mechanism inside providing realistic measurements and dynamic response. Having two allows working on high wattage amps like Ampeg SVT’s or Orange Thunderverb’s with no issues. The Voltmeter and Scope ports are nice features to have.

TOROID Medical Grade Isolation Transformer (2016)

This is an Isolation Transformer originally made for hospital use that I have modified to have isolated ground outlets and changed to a “Tech Grade” IT. It handles a massive 10A of current and weighs about 26 pounds. This allows me to be much safer while working on tube equipment and using an oscilloscope or when working on “Widow-maker” amps that have series filament topology.

MOJOTONE “Canyon” 1x12 Speaker
Cabinet (2016)

This speaker cab was made custom for me by Mojotone in a British style “Red Levant” tolex and a “Salt and Pepper” grill cloth. It is my main test cab for amps on the bench. The nice thing about this is the front porting underneath of the 12” speaker - this gives it a much more profound bass response for a single speaker cabinet than what is usual. It is loaded with a fairly common Celestion Creamback which gives me a good reference tone to compare different amplifiers.

HAKKO FR-301 De-Soldering Gun (2016)

A very handy tool for de-soldering, especially compared to manual solder-suckers or the old-school braid wire. Reliable and very useful when restoring PCB’s with lots of components. I still end up using my Edsyn Soldapullt manual pump a lot - they just work in many situations a gun does not.

PEAK “Atlas” ESR70 Gold ESR/Capacitance Meter (2016)

A great tool for catching electrolytic caps that have failed or are about to fail in a tube amp. Without an ESR meter it is just not possible to tell if e-caps are bad in many situations - especially when you have a more modern amp where age cannot be relied on as an indicator for replacement. Also useful when a customer insists on originality with a valuable vintage amp where keeping every component that can stay truly matters.

KENTON ELECTRIX Audio Frequency Function Gen. (2016)

Custom circuit based on the 555 timer IC - made by my mentor Jim Kramer. An alternative to my RCA WA-504A that has easy to use 1/4” jacks - perfect for inputting to a guitar or bass amp. It has both Triangle and Square Waves available with a frequency range that is in the low-mid range of a guitar. There is something to be said for simplicity.

B&K “Dyna-Jet” Model 707 Tube Tester (1962)

This is a Dynamic Mutual Conductance tube tester that is far more accurate than your commonly found gas/emission tester. It can actually tell if tubes are matched by Gm/Gain and predict the lifespan of any tube as well as many other faults like shorts, gas, grid emission, and even obscure grid-to-cathode leakage. The original 80 Type tube rectifier was replaced with a more reliable and safer solid state rectifier. Socket 24 was modified to do full scale readings of the 12AX7 only. This is one of my most valuable and useful tools.

RCA “VoltOhmyst” WV-77E VTVM (1964)

A Vacuum Tube Volt Meter made by RCA in the 60’s. I use this as a alternative to my Fluke 87 V when I need the sensitivity and impedance of an analog meter. It also can measure up to 4000vac/1500vdc which gives me a higher range than a DMM. This one was built as a kit by a USAF engineer who’s son sold it to me as part of an estate sale. I recapped it and factory calibrated it (it came with all the original assembly drawings/schematics and calibration instructions) and now it functions like new.

HEATHKIT Model IP-32 Regulated Power Supply (1961)

The IP-32 is a Vacuum Tube based circuit that can provide up to 400 VDC for a B+ supply, 100 VDC for a C- bias supply, and a 4A 6.3 VAC heater supply simultaneously. They are all completely regulated with 0A2 Glow-Discharge tubes, which means no matter how big the load is it will not sag or distort in any way. I use this to start up amps that have a blown PT/PS and for designing custom circuits. It allows me to experiment with new designs without having to build a power supply every time. This unit has had a full cap job, all resistors/diodes replaced with upgraded types, and new stainless steel hardware.

B&K “Dyna-Jet” Model 606 Tube Tester (1968)

I use this as a backup and alternative to my more sophisticated B&K 707 tester - This is it’s matching little brother in the same model range/family. This one however is a Gas/Grid Emission tester which uses a more simple circuit and catches more basic faults within tubes. Still, it is a very handy piece that I’m happy to have in my collection.

VALLEY PEOPLE “Advantage” Model 310 (1979)

This is an Audio Noise and DB Level Meter that is useful for assessing the Signal-to-Noise ratio an amp or recording device produces. It also has different types of Decibel readings with many available Filters and Weightings. A very rare piece produced by a company more renowned for its studio compressors and pre-amps. I have never seen another one for sale.

FLUKE 87 V Digital Multimeter (2016)

A recent production Fluke Digital Multimeter. This is the king of all DMM’s and is my main meter I use on every piece of gear. A piece of kit every good tech has to own.

WELLER WES51 Analog Soldering Station (2016)

This is an industry standard workhorse and it never lets me down. Not much to say here, it just works!

WEBER “Z-Matcher” Impedance Matcher (2016)

This is a handy device for Impedance matching amps with outputs different from an available cabinet/speaker. I use this when I get an amp I don’t have a matching cab for or when I need to dummy load an amp that has an unusual impedance output like 2.6 ohms or 5.3 ohms. It also has jacks for allowing parallel configurations to amps that have only one output.

SPARKFUN 303D SMD Rework Station (2016)

This is nice for the occasional SMD work or use as a heat gun for heat shrink tubing, heating glue joints etc. I don’t like Surface Mount parts, and like working on them even less, but sometimes it is unavoidable.

KENTON ELECTRIX Lightbulb Current Limiter (2016)

This is a homemade device that runs the hot wire of a 120vac wall outlet through the filament of a 200watt incandescent photo bulb. It limits the current draw of any amp plugged into it by burning it as heat through the lightbulb - thus saving any amp that has a short in the wiring, tubes, or transformers from a total meltdown.

PEAK “Atlas” DCA55 Semiconductor Analyzer (2016)

Useful for testing transistors for faults like leakage or for correct HFE gain ratings where multiple need to be matched. Nice to have for Hybrid amps or Effects Pedals like a vintage Fuzz Face. It also works on old Germanium transistors which is handy for working on classic effects.