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This new combo amp in the works 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 the original Horn Amp Combo I made about fifteen years ago. This model will use the splendid Eminence 8-inch guitar speaker rear-loaded with a vertical horn. The obvious follow up to this project will be a symmetrical pair of hi-fi mono blocks with a 6 1/2″ Fostex speaker.

All that’s left to do is apply the finish to the amp and horn, wire up the amp and machine the back panel. More pics soon!

Since the Gimbal Horns are going to be hanging from the ceiling, utmost care is required for the design of the support mechanisms. Its mounting hardware is machined from aluminum rod stock. Simple details like this contribute to the structural fortitude of the final product.

In order for the mounting hardware to be flush fit to the cylinder, I created a special fixture that cuts the matching radius of the cylindrical compression chamber, ensuring a perfect fit. An indexing plate is attached to one side of the cylinder so that a hardened steel pin can fit through a press-fit bushing in the yoke and determine the horizontal orientation of the horn. Holes are transferred from a template and drilled into their respective parts.

Below is a slideshow of photos taken during the building process. Check our my other Blog posts for more information and photos about this newest Specimen.
Gimbal Audio Horn Speakers taking shape, part 2
Gimbal Audio Horn Speakers taking shape, part 1

The Gimbal Horns are so named because they are adjustable on two axes. They are ceiling mounted and this exploits a part of interior architecture that is often overlooked.

These horns are being made in our usual fashion – bending recycled newsprint over a steaming iron using a mandrel. The panels are then glued together and reinforced with dryer lint. Special alignment fixtures assure correct orientation of the mounting flanges. The cylindrical compression chambers are laminated together using birch wood wrapped inside a jig using an inflatable ball as a clamp. This forms an extremely rigid platform for the driver and horn.

Here is a slideshow of photos taken during the building process. More info and photos about this project can be found in my other Blog posts:
Gimbal Audio Horn Speakers taking shape, part 3
Gimbal Audio Horn Speakers taking shape, part 1