4
INTRODUCING THE A-5000 DHT 300B, SINGLE-ENDED, PURE DIRECT HEATED TRIODE
MONOBLOCK POWER AMPLIFIER
The A-5000 DHT monoblock, like all Allnic Audio products, uses Permalloy (iron and nickel alloy) for its
transformer cores. Allnic is grateful to Mr. G.W. Elmen of Western Electric for inventing Permalloy for
transformer core use, and in so doing, providing an enormous service to recorded music listeners
everywhere.
The A-5000 DHT has the following features:
•
All Direct Heated Triodes
– The A-5000 DHT monoblock amplifier is a pure direct heated triode, tube
rectified power amplifier. It uses only direct heated tubes in the signal path, from input to output. The
first stage is a new old stock Marconi HL-2; the second is a new,
Allnic in-house manufactured
RS242,
replacing the previously used NOS
3A-110A
; the third is the famous 300B. The rectifier tube is also direct
heated, a 5U4G (or direct heated equivalent). This is an ideal combination of pure direct heated triodes,
resulting in unparalleled faithfulness to the incoming signal, incredible musicality and detail, and quick,
articulate bass.
•
Real power drive
- The driver tube is the Allnic in-house manufactured RS242. Allnic uses this direct
heated triode RS242 tube to drive the 300B to its correct specifications via a choke plate inductor. The
choke inductor (with a 100% permalloy core) has very low power loss and an infinitely high load
impedance. This configuration is an ideal drive stage for the single ended 300B and produces 10 watts of
pure class A, extremely low distortion, high power output.
•
Nickel alloy output transformer
- Allnic uses sophisticated ratio mixed nickel permalloy PB cored output
transformers. Because of their extremely high initial permeability, it is possible to use lower turns on the
primary winding while retaining very high 'open circuit inductance”. That means a resulting very wide
frequency range and low distortion bass response. The A-5000 DHT uses the very latest version of Allnic’s
transformers. This is another reason why the A-5000 DHT excels over other 300B power amplifiers. Allnic
also uses a very big nickel core, so as not to be magnetically saturated at a high current of level of 200mA.
•
Fixed bias control grid
- Allnic prefers to use low distortion and high output “fixed-bias” rather than the
relatively higher distortion and lower output “self-bias” method. That way, it is possible to eliminate the
use of cathode resistors and their associated heat production.
•
Natural negative feedback
- The A-5000 DHT applies about -6dB of negative feedback. This is a very
complimentary amount of negative feedback that differentiates the Allnic 300B single ended amplifiers
from the standard, which have a very coloured and weak speaker driving force. With this natural feedback,
the A-5000 DHT has a relatively high “damping factor', very low distortion, and a higher S/N ratio, without
losing the signature, single ended natural sound quality.
•
Hard wiring
- The A-5000 DHT is all hard wired; circuit boards are not used.
•
Beautiful 20KHz square wave response
. See Figures 1-3.
