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|19th January 2015, 08:23 PM||#1|
Join Date: Jan 2015
Location: Georgian Bay
Aikio Line Stage
Adventures with Aikido: The Line Stage
About two years ago I machined the case work for an Aikido line stage and a year ago I finally got around to assembling it.The amplifier circuit is a point to point wired version based on the All-In-One board that I used for my headphone amp (see my previous post).It’s a two chassis affair (see photos).The power supply uses one of Broskie’s PS-1 boards and two EI core Hammond transformers.The volume pot is an old Alps black beauty and the two switches either side of it are from Broskie as well and select input and are a Mono-Stereo-Mute switch.The switch on the power chassis is a Broskie unit as well that allows the filaments to be energized first and the B+ after the filaments have warmed up.
The four tubes are 6CG7s running at 300 volts B+.I selected the 6CG7’s as they worked well in the first stage of my Aikido HPA and are easily available new from Electro-Harmonix.The Electro-Harmonix are my second favorite 6CG7.My favorite 6CG7 being the NOS GE “hot wires”.
Smooth detailed mid-bass, midrange and treble.The low bass has a bit of the old fashioned tube warmth.I thought the bottom might have slightly tilted frequency response but it measured flat.This “fat” bass seemed to slow the music down a bit.The fat bass is a bit too much of a good thing on my system though it might be ideal for warming up a cool sounding set up.All of these comparisons were relative to a much more expensive ARC line stage so the little Aikido isn’t too shabby really.The Aikido was very quiet.Just a very slight hiss that could only be heard with my ear pressed right against the tweeter of my 90db sensitive speaker.
What I’d do different next time:
I think I’d go back to the tube selection I used with my HPA; 6CG7 input tubes and 6DJ8 outputs and lower the B+ to about 200 volts.This I think would give more tube rolling combinations to tune the sound as desired.One of my favorite 6DJ8’s is the dirt cheap Tesla (not JJ) ECC88 available from Tubemonger.com starting at 30 bucks a pair!
Please note that the Aikido All-In-One boards are no longer available.The equivalent can be built up using one of the Broskie PS-1 power supplies and either two mono or one stereo Aikido board.
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