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Old 26th November 2012, 04:29 PM   #3111
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I meant in general ratio, not 100% matching. At the very least, it would tell you the importance of having it flat across frequency. In reality, things start to become background above 8K-10k
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Old 26th November 2012, 04:57 PM   #3112
lhquam is offline lhquam  United States
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What I was really interested in with these curves was the variation of phase of H2 vs. frequency. Nelson has talked about having a positive (expansion) or negative (compression) phase relation between the H2 and H1, but this relationship is obviously non-constant for the F6, even over the range from 100Hz to 5000Hz, where there is about 100 degrees phase change.

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I meant in general ratio, not 100% matching. At the very least, it would tell you the importance of having it flat across frequency. In reality, things start to become background above 8K-10k
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Old 26th November 2012, 05:01 PM   #3113
generg is offline generg  Germany
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Hi Ihquam,

be cautious, if you continue to analyse in such a brilliant way, will engage you in the F6, F7, F8 production.....!

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Old 26th November 2012, 08:24 PM   #3114
ra7 is offline ra7  United States
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If I had a 300B amp, I would mail it to lhquam asap. That was very interesting! Thanks.

I think the relative amplitude and phase of harmonics is what imparts a characteristic sound. You may be on to something here.

Last edited by ra7; 26th November 2012 at 08:26 PM.
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Old 27th November 2012, 12:37 AM   #3115
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If I had a 300B amp, I would mail it to lhquam asap. That was very interesting! Thanks.

I think the relative amplitude and phase of harmonics is what imparts a characteristic sound. You may be on to something here.
I find your choice of a triode amp for study by lhquam to be interesting. I have speculated in earlier posts that loop feedback in F6 reorganized its intrinsic OLG pentode charateristic curves to triode-like ones; by analogy with Schade Feedback in vacuum tube circuits. OLG F6 is a voltage controlled [modulated] current source which has published pentode characterisics for its output stage JFETs and also for the future diyF6 with output MOSFETs. The question which hangs or put this way: how does one prove whether CLG F6 has been transformed to a voltage controlled resistor like a triode and/or its amp?

Last edited by Antoinel; 27th November 2012 at 12:40 AM.
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Old 28th November 2012, 07:21 AM   #3116
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nelson, The distinction between the F6 op stage and almost every other quasi-comp is pretty apparent but what about f6 vs circs ?

ie what advantage(s) would you reckon between this topology and a transformer input circlotron ? (other than the need for two supplies for the latter I mean.)
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Old 30th November 2012, 02:21 AM   #3117
Botte is offline Botte  United States
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Default Listening session notes

I had a nice listening session tonight and I have never heard another amplifier that reveled absolute phase better. I would go so far as to say that it becomes almost distracting. I would normally just put on something to listen to and go, now I need to test the absolute phase because it is so obvious when it is wrong when I start to listen. I also came across an album that it changes track to track, amazing. Even my SET amps don't reveal it this well. The F6 is truly a special amp.

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Old 30th November 2012, 04:08 PM   #3118
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If you can pick the absolute phase like that, you are fortunate on
several levels.

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Old 30th November 2012, 08:35 PM   #3119
labjr is online now labjr  United States
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Some of these claims need to be tested on mythbusters.
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Old 30th November 2012, 11:24 PM   #3120
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Update

I degenerated the output R100s on my F6 by adding the .1ohm resistor and 10 ohm pot. I need to do more listening but for me:

With each pot turned to get min wiper to source resistance (.3 ohms) I seemed to get widest soundstage, good depth and nice attack

Keeping the Q1 pots at .3 ohms and increasing the Q2 pots so that wiper to source was 1 ohm I seemed to have the best bass and nice detail

The opposite settings was also true Q1 pots at 1 ohm and Q2 pots at .3 gave very nice bass and nice detail

Don't quite understand that but I want to do some extended listening

Question - have others used all four pots/resistors at once or may it be better to use them on Q1 with Q2 at 0 ohms (no pot/resistor) or alternately Q2 with pot and Q1 with no resistor?

Just going my ear right now - seem to be able to duplicate with just resistance measurements.

Thanks and best
Bob
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