July 27, 2012
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Prem. 140 Input Tubes, Pt 1
This is the first installment in a series of postings comparing the effect of various tubes used in the critical input position of the Premier 140 power amplifier.
The idea is to run both of the c-j components (the Premier 16LS2 preamp and the Premier 140 amp) with their original tube types and brands to form a baseline comparison for the one variable: the Premier 140 input tube which came stock with an Electro-Harmonix 6922EH.
Tube Configurations:
Premier 16LS2 preamp: 6 x 6922EH with two silicone O-rings per tube
Premier 140 power amp: 1 x 6922 (varies) with a Herbie’s HAL-O, 2 x Sovtek 6H30π-EB, 8 x SED =C= 6550C
Electro-Harmonix 6922EH Amperex PQ Pinched-Waist 6922
Rating System:Based on a scale of values ranging from -10 to +10 with a baseline value for the 6922EH of 0.
Explanation of Rating Criteria:
Bass: How does the input tube handle frequencies below 160 Hz?
Mids: How does the input tube handle the range of frequencies from 160 – 1300 Hz?
Highs: How does the input handle frequencies above 1300 Hz?
Detail: The subtlest, most delicate parts of the original sound.
Grain: A moderate texturing of reproduced sound. The sonic equivalent of grain in a photograph. The higher the number, the less grain there is.
Dynamics: Giving an impression of wide dynamic range; punchy. This is related to system speed as well as to volume contrast.
Sound Stage: Not only sound stage width, height and depth but also the degree to which the images within the sound field seem to occupy space. So that, for example, an input tube with a wide and deep sound stage populated by flat, two dimensional individual images will be ranked subjectively lower than a sound stage of similar dimensions having more solid images.
Average: The simple arithmetic mean of the seven preceding characteristics. If some of these qualities are more important to you, then you should weight them accordingly. I'm not even sure if it's valid to average these characteristics to begin with but I know that some readers will do this anyway. And so I'm including it for their convenience.
Forward: How close to you does the sound stage appear? The usual analogy places the listener in a concert hall and then refers to her/his row position. Therefore, a perceived Row C position is more forward than a Row M position.
Warmth: A mellow and rich quality in reproduced sound. Warmth is the audible effect of a frequency response which is clockwise-tilted across the entire range, so that output diminishes to some degree with increasing frequency. In my opinion, a certain amount of warmth is a normal part of musical sound.
In this installment, the Amperex PQ Pinched-Waist 6922 (November, 1958 vintage) will be compared to the 6922EH. Here are the results, presented without comment. There may be a comments installment following the final audition posting.
Type Bass Mids Highs Detail Grain Dynamics Sound Stage Avg. Forward* Warmth* 6922EH 0 0 0 0 0 0 0 0 0 0 Amperex Pinched Waist 6922 -1 5 -2 4 7 0 9 3.14 -1 5 * Ratings in this column indicate to what degree the input tube exhibits this characteristic compared to the baseline 6922EH. Depending on the reader’s personal preferences a lower or higher rating may be a good or bad thing.
Further installments will follow as other tubes are auditioned.
