TACs are back and better then ever!

TACs (Tube Adapter-Converters) were designed to offer guitarists great over-driven tone at reasonable volume levels. Introduced in 2002 as “TAD,” the adapters have been redesigned to sound better, last longer, and be compatible with more amplifiers than previous versions. We believe that nothing sounds sweeter than a tube amplifier pushed into overdrive. But, the trick is to do it without causing damage to your amplifier—and without bothering the neighbors! The TACs are a low power tube adapter-converter which adapts the tube pin out to use a 6AK6 tube, and either operate in class A cathode biased mode, or convert the tube to operate in class A cathode bias mode? This depending on the model of TAC and amp they are being installed in? All TACs use the miniature 1-watt 6AK6 tube. This little pentode tube generates a wonderful blend of classic British and American tones at a reduced volume over standard power tubes. Of course, your amp will not sound exactly the same as it did with the stock output tubes, but it will provide a diverse palette of available tones.

The TAC, 1-watt tube adapter is a direct replacement for your amplifier’s stock power tube(s). Simply replace your amplifier’s output tube(s) with the correct version of the TAC adapter and your amp will be instantly converted into a class A, cathode-biased, low power tone monster. TACs offer players cost-effective access to power tube saturation at reasonable volumes while retaining your amp’s inherent tone.

No adjustment or re-biasing is required; 100% PLUG -N- PLAY!

  $50 each / $120 per matched pair

All TACs are shipped with hand selected NOS Cifte 6AK6 tubes preinstalled. We also offer optional NOS RCA black plate tubes, which can be purchased and installed in your TACs for an up charge of $4 each or $8 per pair. Replacement Cifte 6AK6 tubes are available for $6 each, $16 per matched pair or $40 per matched quartet. RCA Black Plate 6AK6s are also available for $10, $24 and $56, respectively. Replacement tube prices include a $4 per pair ($2 per tube) matching charge, or a ($4 per tube) $16 charge for a matched quartet.

NOTE: Because there are so many different models and versions of TACs available, all TACs are handmade to order. They are not mass produced and sitting on a shelf ready to ship. However, most orders will be completed in a few days. Also large quantity orders can be manufactured quickly upon request. Please contact us if you are interested in becoming a distributor of TACs.

Models

There are ten (10) basic models of TACs presently available.
• The TAC-1, TAC-3, TAC-5, TAC-7 and TAC-9 are designed for use in any class A, cathode-bias amplifiers, whether single-ended or push pull, using 6V6, 6L6, etc.* tubes; 7591(A) tubes; EL84/6BQ5/7189(A) tubes; 7868 tubes; or 6973, 6CM6, 6CZ5 and 6GM5 tubes, respectively. Not intended for use in fixed-bias amps, but can be used if the amp’s bias circuit is modified. Which will allow the 6AK6 tube installed in the TAC to operate in fixed-bias mode rather than the standard cathode-bias mode.
• The TAC-2, TAC-4, TAC-6, TAC-8 and TAC-10 are designed for use in any class AB or class A, fixed-bias amplifiers using 6V6, 6L6, etc.* tubes; 7591(A) tubes; EL84/6BQ5/7189(A) tubes; 7868 tubes; or 6973, 6CM6, 6CZ5 and 6GM5 tubes, respectively, whether single-ended or push-pull. Not intended for use in cathode-bias amps.

All models are available in three distinct high voltage ranges.
• TACs marked  L are to be used in amplifiers with a plate voltage (HV) between 300 and 375 volts DC.
• TACs marked M are to be used in amplifiers with a plate voltage (HV) between 375 and 450 volts DC.
• TACs marked H are to be used in amplifiers with a plate voltage (HV) between 450 and 525 volts DC.

We also make 2 custom versions of TAC-1 and TAC-2 to accommodate lower plate voltages used in some obscure amps. There is an L- version to use in amps with a plate voltage of 225-300vdc and also a LL version to cover 150-225vdc.

All TACs are available in pentode or triode (T) configurations. We can also build custom versions of any TAC model to accommodate any voltage range used in almost any amplifier. Contact us with your specific needs.

Most guitar amplifiers operate the output tubes in pentode mode, meaning that all 5 of its electrodes, or connections, are connected and used. When operating in pentode mode, the plate/anode connection of the tube has the full high voltage potential applied to it via the output transformer. The tube also requires a separate lower value of high voltage applied to the screen grid (G2) connection of the tube. The suppressor grid, some times called the beam plate (G3) is usually tied directly to the cathode (K or C), either by an internal connection in the tube, or externally via a jumper wire on the tube socket. The audio signal is then applied to the control grid (G1). Therefore using all 5 electrodes of the tube.

Inversely, some amplifiers may operate the tubes in triode mode, meaning only 3 electrodes, or connections are connected or used. In this configuration, the plate/anode of the tube is still connected directly to the high voltage via the output transformer, but the screen grid (G2) is connected to the plate/anode either directly or via a low value resistor. The voltage on the screen grid (G2) is equal or near equal to the voltage on the plate/anode; these being at approximately equal voltage levels will make the tube function as a triode. In either mode the suppressor grid, sometimes called beam plate (G3) is tied directly to the cathode (K or C), either internal of the tube or via a jumper wire on the socket. The audio source is then fed into the third and final electrode called the control grid (G1).

Pentode mode tends to provide a fuller, more aggressive tone and will also provide maximum output power. If your looking for the maximum volume out of a 1-watt TAC while maintaining the full tone of your amp? Then the pentode version of the TAC is the way to go.

Triode mode, on the other hand, tends to be slightly muted and less aggressive with a bit less frequency response, but exhibits increased linearity and dynamics. The triode version will also decrease the output power of your amp even further. If you are looking to tame your amp’s response and get maximum volume reduction, then the triode version of TACs are for you.

Some amplifiers can use several different models of TACs. Each version can offer a slightly different tone and feel based on the mode of operation and the different high voltage levels applied to the plate of the 6AK6 tubes. We can also build custom TACs to meet your needs. There are many parameters that can be tweaked to attain your desired tone, i.e. high voltage level, input drive level, frequency response and more. Contact us to discuss custom parameters for your needs.

TAC Facts

There are a few important facts regarding the TACs:

First and foremost, most people don’t realize how loud 2-3 watts of peak output power can be.  We have had some players install a pair of TACs expecting screaming overdrive at volumes that will allow the baby to sleep in the next room. The 6AK6 output tubes used in a pair of 1-watt TACs will produce between 2- 3 watts of peak power. Believe it or not, 3 watts of output will offer roughly half the perceived volume of a 30 watt amp. The human ear requires a tenfold (10db) reduction in volume to perceive it as half the volume.

One clear advantage for lower volume situations is that 6AK6s overdrive and compress sooner than larger power tubes. This means, besides having lower overall output, you can set your volume control lower and still attain output tube compression. If the “sweet spot” on your amp was with the volume set at 8-9, try the TACs with your volume control set at 5 or 6.

It’s also worth noting that the overdrive tones we love are almost always a combination of preamp tube, power tube and speaker distortion. An amp running 3 watts won’t drive 50-watt speakers the way larger output tubes will, but it will still drive them very nicely. Many customers will use an extension cabinet with lower power speakers installed to get the greatest tone out of the TACs. Also many players will still use an overdrive pedal to drive the amp’s input harder. The 6AK6 tubes can sound very much like 6L6 or 6V6’s, but with a little more bite when pushed hard. Amps using any of the standard American output tubes (i.e. 6V6, 6L6, 5881, 7581, 7027A, 6550, 8417 etc.) will retain their inherent tone beautifully with TACs installed. Replacing tubes such as EL34s with TACs in a Marshall or other British amplifier, will offer a slightly more “Americanized” tone. We have designing several new versions of the TACs to allow use in more of the most commonly used guitar amplifiers. Additional tube models such as 6AQ5/6005 will soon be able to be replaced by 6AK6s using TACs. TACs will reduce your amp’s output power while running the 1 watt 6AK6 tube(s) in class A, cathode-biased mode. Installing the correct TACs in your amp will not endanger any components in your amplifier including your transformers, unlike some power attenuators on the market. The 6AK6 tubes used in our adapters have less current draw than stock tubes. This lower current draw creates less of a load on both the power and output transformers and the power supply circuitry. The drastic reduction in output power and heat generated will keep your transformers running as cool as a cucumber. Typical output tubes used in amplifiers can draw 25-180ma of plate current each, while our TAC adapters typically draw about 10-15ma each—again, less of a load on the power transformer.

TACs should last for many years. Any electronic component can fail, but TACs are a very high quality, hand-built and reliable product. Each TAC is meticulously built, one at a time, proudly in the USA with high quality components. However, the matched 6AK6 tubes in the TACs will, of course, be working harder than your stock output tubes. To get the desired tone, most amps will be driven very hard and turned up very high on the volume control. The 6AK6 tubes should provide several years of service, but greatly depends on use. The 6AK6 tubes used in the TACs should be replaced when the tone quality begins to deteriorate or diminish. Thus, we offer single, matched pairs, and matched quartets of replacement 6AK6 tubes for your TACs.