And whenever Mr.Nixie takes such a stuff into his hands, neither the sound nor the possibility of extensive tube-rolling is left behind. And so, for the first time an amplifier on the market can feature not only different brands of one tube type, but also a whole range of tubes - which are still manufactured today - namely the ECC81, 82 and 83 series.
These tubes are still in service today and were used in the past in almost every audio device or amplifier.
The AGNETA headphone amplifier now offers the willing audio nerd a nearly inexhaustible possibility to test his own tube treasure and finally to find out "his" tube with "the sound par excellence".
Which tubes exactly can be used?Thanks to a careful voltage feedback, all double triodes of the types ECC81, E81CC, ECC82, E82CC, ECC802S, ECC83MG and 5751 and their international versions such as 12AT7, 6201, CV4024, CV455, 12AU7(WA) CV4003, CV491, 12AX7MG, CV4004, 6057, 6681, 7025 and many others, whereas the heater is connected to pin 4 and 5 plus the filament center tap to pin 9 and the heater current is 12.6 V @ 150 mA in series or 6.3 V @ 300 mA in parallel connection.
For this reason, the types 12BH7-A or ECC99 are not suitable because their filament power is too high or the ECC832 or 12DW7 because they have triode systems with different amplification.
Also Russian double triodes (e.g. 6N2P ~ ECC83) cannot be used, because these tubes do not have the center filament connection on pin 9, and have (like the 6N1P or 6N3P for example) different socket layouts.
With regard to the lifetime, not only the low anode current of 2 mA per triode system (at stabilized 170 V anode voltage) but also the controlled preheating of the tubes with 2 x 150 mA constant current is to be valued as highly tube-friendly.
A two-color LED in the tube socket discreetly indicates the current operating status (red = preheating - no signal, champagne color = operation).
- AUX input on front
Normally you're listening during operation to the signal present on the Line IN RCA jacks. But when connecting to this front 1/8" TRS jack another audio source like iPod or other high quality player for example, than this AUX signal is feeded to the amplifier.
- LINK output jacks on rear
These jacks feed the by Relais "hard wired" signal from the Line IN jacks, when the amplifier is turned off. During operation of the amplifier the LINK signal source can be selected with a slider switch on the top panel:
Slider to RCA = The Line IN signal is always feeded to the LINK jacks regardless if another listening source is connected to the 1/8" TRS jack.
The green LED is illuminated.
Slider to AMP = The tube amplifier's output signal (with athe adjusted volume level) is feeded to the LINK jacks. With this trick the AGNETA amp acts as a kind of "tube sound enhancer" of the Line IN signal, or - when connected another source to the 1/8" TRS jack - of this AUX signal.
The yellow LED is illuminated. The processed signal is decoupled via 2.1 kohms resistors from the power stage.
- Headphone connectors on front
Beside to the standard 1/4" TRS jack there's another 1/8" TRS jack present for connecting a second headphone in parallel.
- And last but not least
Designed and handcrafted in Germany in small quantities with lead-free silver solder, assembled with through hole components which have been acquired - wherever possible - in Germany.