Horn Amp Combo

This new combo amp is for amplifying stringed instruments. The cabinet follows the construction details of both the Specimen Tube Amps and Horn Speaker bases. It also uses the engine turned sub-plates for convection cooling found on Specimen’s Octoblock and the slotted side panels that were first used on Specimen’s Fifty-watt Tube Amp. You could say it’s a clever combination of several Specimen innovations all rolled into one beautiful package.

This project stemmed from a request to revisit Specimen’s original Horn Amp Combo made about fifteen years ago. This model uses the splendid Eminence 8-inch guitar speaker rear-loaded with a vertical horn.

The circuit is essentially a 5E3 Tweed schematic converted to 6SL7 preamp and driver section. There are multiple taps on the output transformer so that 6V6 or 6L6 power tubes can be used. The amp is shown here with the Tung Sol reissue 6L6G in the large ST bottle shape. The sound stage and transient response of this amp are particularly interesting. What we get from an eight inch speaker rear-loaded with a horn creates an almost holographic effect, as if the sound is coming from behind the amp.