Posted by 2wo [ 71.242.84.100 ] on June 20, 2006 at 23:28:33:
In Reply to: Re: tried the 6688 posted by Damir on June 19, 2006 at 01:02:17:
Yea, I was expecting a subtle difference between the two types. But no, it sounds like someone put a wet blanket over the speakers, only with less bass. The best way to describe it is it sounds like the tubes were thoroughly worn out and then some. I am sure that they are new, they test fine and each on there own sound the same.
I tried them at the same OP as the D3a, Ia 9.5ma, Va 192, Vgk of 2.2V. these Measured with the D3a. the cathode is still not bypassed. will try that down the line. I have a 1k cc, g1 stopper, and a pair of 460 cf for the cathode. I did not detect any oscillations with the D3a. I did not check but would expect less trouble with the lower mu tube.
The D3a setup, as it breaks in is sounding very nice. I will at some point try a different cathode scheme and will keep my eye out for another set of 180’s . I will continue to try them as I make changes…John
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