 
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
|
|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
66.81.65.197
In Reply to: Re: Problem solved: feedback was disconnected... posted by Soundmind on August 28, 2004 at 14:25:41:
But the pentode of the 6AN8 generates too much distortion and I decided to go to a triode front-end. In this case, I elected to go with a differential stage. There are many examples to that, but I also noticed that the amp inverts phase in its original form and wanted to fix that.
Ended up with a single differential stage and the feedback goes to the (-) side of the diff stage. The final result is a non-inverting amp with much more "body" to its sound.
I still have to tweak this stage, but at low power it already sounds quite promising!
I can see other improvements, but I'll get this front-end right first and only then move on to the complete package...
Follow Ups:
When this amplifier was originally introduced, nobody ever considered that absolute phase inversion/non inversion was an issue. It wasn't until decades later that anyone thought about it. I'm trying to avoid flame wars but I personally cannot understand how this could be audible. However, interesting point is that I am experimenting with two different amplifiers for biamplifying a speaker system and the relative phase inversions between the two are important so that I know if my tweeters are in or out of phase with my mid/woofers. It suddenly occurred to me that it's easy enough to find out. Just connect a small full range driver to the same channel of each one, use them as headphones and it will be obvious if they are in or out of phase. As for absolute phase, I suppose I could just hook up a woofer in phase according to the markings and just see what happens if I touch the pos end of a 1 1/2 volt battery to the input with the neg side to ground. If the cone first moves forward, I assume it is non inverting. If it first moves backwards I assume it is inverting. Do you think that is right?BTW, I think the one aspect of this amplifier that many audiophiles considered outstanding is the output transformers. I know someone who bought a pair just for that and chucked the rest.
I think a small percentage of people are sensitive to absolute phase. I perceive phase inversion in both channels as a shift of soundstage to the left, for some reason.
Many times I find tracks that are recorded in inverse phasing and it's audible to me (in an annoying manner).
The trannies on the MkIII are BIG BIG BIG!
They look nice too. However, I already found several resonances...
I guess the mechanical aspect can be easily tweaked. I'm building the mod on a proto board from AES, with components ynder the chassis.
It looks absolutely cool relative to the original!
This post is made possible by the generous support of people like you and our sponsors:
Top of Page ]
[ Contact Us ]
[ Support/Wish List ]
[ Copyright © 2025, Audio Asylum, all rights reserved ]
