Bias Master™ system BM4 Measures Bias current of the vacuum tubes in your amp. Includes 4 probes and english/german operation manual. The Bias Master™ allows you to monitor the bias current safely and easily. While adjusting the Bias control pot of your amp, the Bias Master™ shows the actual result. This lets you set and evaluate the full reasonable biasing range your amp and tubes offer to find and set your personal perfect choice.

CTS 10K linear bias potentiometer. This panel mount trimpot is used in many Fender® amplifiers.

Please note: This potentiometer does not include the washer and nut. If you would like to purchase the washer and nut, see our part number R-VNUT-38

22kΩ linear taper. Used as bias / trim potentiometer for JMP.
For a same-brand generic replacement, see R-V25KV-BP.

Bias Master™ set of adapter probes for testing other types of tubes. For use with the S-TBM4-X Bias Master™ system.

• Primary 115 VAC, 60 Hz.
• Designed for small power or bias supplies, test equipment, preamps etc.
• Models P-T261C6, P-T261E6, and P-T261G6 can also be used with full wave C.T. rectifiers.
• Economical , two hole, channel bracket, chassis mount.
• Minimum 5" long leads.
• Convenient 6.3 filament/auxiliary winding.

• Primary 115 VAC, 60 Hz.
• Designed for small power or bias supplies, test equipment, preamps etc.
• Economical , two hole, channel bracket, chassis mount.
• Minimum 5" long leads.
• Convenient 12.6 filament/auxiliary winding.

The YJS is a specialized, current-limiting/voltage-conditioning adapter for use in most 20 to 100 watt amps that use 6L6, EL34, 6550 or 6V6 output tubes. The YJS is for amps with fixed bias power tubes. (Fixed bias tubes have their cathode connected directly to ground and a negative DC voltage applied to their control grid).

The JJ Electronic EL84 is a solidly built EL84 / 6BQ5 with excellent tonal qualities. JJ’s rugged construction of this tube offers high reliability without any compromise to the sound. This tube has solid lows with warm bright mids and shimmery highs. When saturated the harmonics are rich and dynamic. The JJ EL84 nails the classic sound of this tube. This tube can replace any EL84 or 6BQ5 tube.

The FatKeys™ SSI2164 is perhaps the most flexible VCA available, with four independent channels for lowest cost-per-VCA. The user-selectable mode control allows Class A, AB, or intermediate biasing, and current inputs and outputs provide great design freedom. Ideal for voltage-controlled filters. The SSI2164 is a versatile VCA building block for high-performance audio applications. Four independent channels provide voltage control of current-mode inputs and outputs for a gain range from +20dB to –100dB, with control provided by a ground-referenced –33mV/dB constant. The SSI2164 will directly retrofit existing SSM/V2164 positions while offering improvements that include significantly lower overall distortion, on-chip protection against asymmetrical power failure, and a substantial increase of input current handling. The device offers considerable flexibility for a wide range of design goals and applications.

The TL072 is a high speed JFET input dual operational amplifier incorporating well matched, high voltage JFET and bipolar transistors in a monolithic integrated circuit. The device features high slew rates, low input bias and offset current, and low offset voltage temperature coefficient.

This Russian tube is full bodied and bright with a more straightforward presentation. It packs a lot of bite with its higher-than-normal gain. In overdrive, it offers a lot of crunchy fizz. High gain preamplifier tube with ultra low noise and detailed, musical tone. Unique spiral filament eliminates filament to cathode induced hum common on amplifiers that use AC on the filaments.

High quality 25 Series resistors from Ohmite. These 5W wirewound resistors are a great choice for screen grid and cathode bias resistors in tube amplifiers. The brown enamel coating used by Ohmite looks great in vintage and vintage-style amps. The 25 Series axial terminal resistors are both durable and economical.

High quality W22 resistors from Welwyn / TT Electronics W20 Series. These 7W wirewound resistors are a great choice for screen grid and cathode bias resistors in tube amplifiers. The brown enamel coating used by Welyn looks great in vintage and vintage-style amps. These resistors can be found in many vintage Marshall amplifiers. A high purity ceramic substrate is assembled with interference fit end caps to which are welded the termination wires.

The JJ Electronic 12BH7-A is a faithful reproduction of the original tube. Its rugged construction offers high reliability. The JJ 12BH7-A can be used as a replacement for any 12BH7 tube.

The JJ Electronic 5881 is very similar to the 6L6GC but with a plate dissipation of 23W rather than 30W. Another physical difference is the shorter bulb. These tubes have a soft and balanced response that sounds great in both guitar amps and hifi equipment. The JJ 5881 will work in any amp that uses 6L6 tubes.

High quality W21 resistors from Welwyn / TT Electronics W20 Series. These 3W wirewound resistors are a great choice for screen grid and cathode bias resistors in tube amplifiers. The brown enamel coating used by Welyn looks great in vintage and vintage-style amps. These resistors can be found in many vintage Marshall amplifiers. A high purity ceramic substrate is assembled with interference fit end caps to which are welded the termination wires.

Dual Operational Amplifier. The NJM4558 (JRC4558) integrated circuit is a dual high-gain operational amplifier internally compensated and constructed on a single silicon chip using an advanced epitaxial process. Combining the features of the NJM741 with the close parameter matching and tracking of a dual device on a monolithic chip results in unique performance characteristics. Excellent channel separation allows the use of the dual device in single NJM741 operational amplifier applications providing density. It is especially well suited for applications in differential-in, differential-out as well as in potentiometric amplifiers and where gain and phase matched channels are mandatory. Features:

• Operating Voltage (±4V~±18V)
• High Voltage Gain (100dB typ.)
• High Input Resistance (5MΩ typ.)
• Bipolar Technology

• Designed for drop in replacement of original units.
• Physically, parts were designed to look similar to original factory units (where possible).
• Material used & design specs. were kept as close as possible to the original part to preserve the stock "tone".
• See P-T290-FENDER-120-UP for upgraded 120 V transformers, P-T290-FENDER-240 for 240 V transformers

Warning: Not all amplifier models of the same name use the same transformer model.

The LM13700 series consists of two current controlled transconductance amplifiers, each with differential inputs and a push-pull output. The two amplifiers share common supplies but otherwise operate independently. Linearizing diodes are provided at the inputs to reduce distortion and allow higher input levels. The result is a 10-dB signal-to-noise improvement referenced to 0.5 percent THD. High impedance buffers are provided which are especially designed to complement the dynamic range of the amplifiers. The output buffers of the LM13700 differ from those of the LM13600 in that their input bias currents (and thus their output DC levels) are independent of IABC.

Electro-Harmonix 12AT7 / ECC81 Vacuum Tube Large plate format, superior dissipation over the originals. Perfect for reverb and driver circuits.

Octal power tube (Max Plate Watts = 14W) Beam power tetrode with a specially developed cathode coating, careful alignment of the grid, tri-alloy plate material for flawless performance up to 475 volts. Perfect for high plate voltage amplifiers like the Fender Deluxe Reverb.

Electro-Harmonix has released a low noise, low microphonic version of the 12AX7 that meets all specifications required for the tube to be designated 7025.

Tung Sol 12AT7W / 6201 dual triode preamp tube. Made in Russia. Premium Twin Triode ideal for use in reverb and driver circuits. Superior dissipation compared to NOS versions of this tube.
• Extra-low microphonics makes it the best 12AT7 choice for reverb circuits. Also suitable for HiFi.
• Factory selected for closest tolerances and most consistent performance
• ECC81 equivalent

OPA2134 SoundPlus™ Audio dual op-amp with low distortion, low noise and precision. The OPA2134 are ultra-low distortion, low-noise operational amplifiers fully specified for audio applications. A true FET input stage is incorporated to provide superior sound quality and speed for exceptional audio performance. This, in combination with high output drive capability and excellent DC performance, allows for use in a wide variety of demanding applications. In addition, the OPA2134 has a wide output swing, to within 1 V of the rails, allowing increased headroom and making it ideal for use in any audio circuit. The OPA2134 SoundPlus™ audio operational amplifiers are easy to use and free from phase-inversion and the overload problems often found in common FET-input operational amplifiers. They can be operated from ±2.5-V to ±18-V power supplies.