THD escaped much of this criticism by using thick boards with large ground planes to reduce noise, as well as through-plating and use of Teflon wire for durability.

THD also does not mount their electro-mechanical components like jacks, potentiometers, switches and tube sockets to the board.

These circuit board quotes include: In 1987, THD Electronics put the first vintage reissue vacuum tube guitar amplifier into production, the 4-10 amp.

It was modeled after a 1959 5F6-A "tweed" (a misnomer: the cloth is actually twill) Fender Bassman[3] and, unlike the Peavey Classic Amplifiers of the 1970s (which were covered in twill-patterned vinyl) the 4-10 was covered in authentic cotton twill, the first since Fender and Gibson stopped production of twill-covered amplifiers in 1960.

[1] Although it, too, was physically styled after the Fender Bassman (and was also available in tweed), electronically and sonically, it was meant to mimic an early JMP Marshall.

In 1992, Guitar Player Magazine conducted a one-to-one test with a 1973 JMP Marshall 50-watt amplifier head, and found the two sounded “very close”.

[1] For the last 18 months of the Plexi's production, several minor circuit changes were made, prompting THD to rename it the “Type-O”.

[13] Although usually covered in black vinyl, cream, brown and blue paisley-colored 2x12" extension cabinets were manufactured as well.

The concept started in the late 1980s as a way to in-house test the company's amplifiers without the technicians’ suffering hearing loss.

The Hot Plate has a Line Out jack, which can be used to send a DI signal to the mixer, or to insert equalization, time effects, and possibly a solid-state amplifier between the distorting tube power amp and the guitar speaker.

In 1994, Guitar World Magazine conducted a test in which Yellow Jackets were installed in a 100-watt Marshall Plexi Reissue.

[16][17] The etched design on the amplifier's front panel was made to resemble the work of artists and architects Charles Rennie Mackintosh and Frank Lloyd Wright.

Billy Gibbons (of the band ZZ Top) requested serial number 007, and model 666 (which is written on the back of the UniValve chassis in red ink) is owned by a former THD employee.

[19] In that test, the BiValve-30 was given a slightly lower score in the “value for money” category, and the accompanying written review stated: “…definitely an amp for the well-heeled purist”.

The Flexi-50 amplifier head was released in 2003, and made its debut at that year's Music Live event in the UK.

), Eric Clapton, Charlie Daniels, Bob Dylan, John Fogerty (Creedence Clearwater Revival), Billy Gibbons (ZZ Top),[1] Paul Gilbert (Mr. Big),[21] Kirk Hammett (Metallica), Mick Jagger (The Rolling Stones), Mark Knopfler (Dire Straits), Mick Mars (Mötley Crüe), Steve Miller, Bob Mould (Hüsker Dü, Sugar), Jimmy Page (Led Zeppelin), Prince, Chris Poland (Megadeth, OHM), Brian Setzer (Stray Cats, Brian Setzer Orchestra), Dan Spitz (Anthrax), George Thorogood, Eddie Van Halen (Van Halen), and Stevie Ray Vaughan The official THD website includes a much more comprehensive "THD Artist List".