Homebrew 6BQ5 / EL84 Mono Tube Amplifier
Archived listing from the original vintage-amplifier.com. Prices, seller details and purchase links have been removed; this page is a reference record, and nothing here is for sale. About this archive.
Very cool old 1950’s Vintage Homebrew 6BQ5 / EL84 Mono Tube Amplifier Amp with a Triad 14A transformer & an Amperex Bugle Boy EZ81. It comes with 2- GE/Mullard 12AX7’s made in Great Britain, 2- Raytheon 6BQ5’s and an Amperex Bugle boy 6CA4/EZ81 as shown. It measures about 11″w x 8″d x 6″h at 15 lbs.
About this model
A 1950s home-built mono amplifier with a Triad 14A transformer and a complete tube set: two GE/Mullard 12AX7s made in Great Britain, two Raytheon 6BQ5s and an Amperex Bugle Boy 6CA4/EZ81 rectifier. It measures about 11 by 8 by 6 inches and weighs 15 pounds.
Two 6BQ5s (the American name for the EL84) in push-pull suggest a 10-to-15-watt amplifier, a common hobby design of the period. With no schematic, judge a build like this by its wiring and parts, and check the transformer against its maker's data.
| Builder | Unknown, home-built, 1950s (listing) |
|---|---|
| Type | Mono tube amplifier |
| Output tubes | 2 × 6BQ5 / EL84 (Raytheon) |
| Other tubes | 2 × 12AX7, EZ81 / 6CA4 rectifier |
| Transformer | Triad 14A (listing) |
| Size and weight | About 11 × 8 × 6 in, 15 lb (listing) |
Questions collectors ask
Can I fit EL84s where a homebrew schematic calls for 6BQ5s?
Yes. 6BQ5 is simply the American designation for the EL84 power pentode, so the two are interchangeable.
How powerful is a pair of 6BQ5 tubes in push-pull?
About 17 watts in class AB, according to the EL84 data cited by Wikipedia; home-built amplifiers often ran them more gently.
Sources: Wikipedia: EL84.
