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Vintage threads from the first ten years

previous: dr.kt88 well, get a additional, small PT 25... -- 2/23/2004 11:17 AM

Re: Screen Grids Article

2/23/2004 2:57 PM
Mikko	Re: Screen Grids Article Thanks, I've always respected much what comes to doctors (special) orders. Well, I have one particular rhythm sound I wanna improve when asking all these questions. Something says to me that lowering the Vg2 voltage will perhaps help the overall tightness of the tone especially if there is great amount of speaker resonance boost coming from the preamp, like in this old (out of tune, broken guitar) test clip of mine: http://www.kolumbus.fi/fractal.wonderland/withKT88s.mp3 In the clip the bass boost was set full and even the sound is quite defined and acceptable I want it to be still tighter (without changing tone stack say from std. marshall types to something very trebley like 1000p, 47nf, 47nf, 100k slope...or lessening the preamp filtering, power supply resistors, making smaller coupling caps etc. "band aid" fixations.) Now when I'm gonna buy additional tranny for screens (btw, 269JX, 270AX, 269GX are all fine?) and using 278CX for power tube plates and the rest of the amp, how its best to do the preamp regulation and voltage dropping (there should be much more than 300V on 12ax7 plates?)...anyways, I hope that the bass will be same or tighter with better preamp regulation process. OR is there a change it'll go "mushier" or completely "choked" with the better regulation process. Btw, the clip was made with a pair of kt88s, played with very low volume and I guess the 273BX tranny was not sagging at all in those circumstances. So - as a summary - I'm expecting better overall tone in future when using 278CX instead of 273BX. Secondly I'm expecting better overall tone when lowering those Vg2 voltages. Third, I like to think (or hope) that the better regulation in preamp will not cause the preamp boosted speaker resonance go any "mushier". Mikko

2/23/2004 2:57 PM

Mikko

Re: Screen Grids Article

Thanks, I've always respected much what comes to doctors (special) orders.

Well, I have one particular rhythm sound I wanna improve when asking all these questions. Something says to me that lowering the Vg2 voltage will perhaps help the overall tightness of the tone especially if there is great amount of speaker resonance boost coming from the preamp, like in this old (out of tune, broken guitar) test clip of mine:

http://www.kolumbus.fi/fractal.wonderland/withKT88s.mp3

In the clip the bass boost was set full and even the sound is quite defined and acceptable I want it to be still tighter (without changing tone stack say from std. marshall types to something very trebley like 1000p, 47nf, 47nf, 100k slope...or lessening the preamp filtering, power supply resistors, making smaller coupling caps etc. "band aid" fixations.)

Now when I'm gonna buy additional tranny for screens (btw, 269JX, 270AX, 269GX are all fine?) and using 278CX for power tube plates and the rest of the amp, how its best to do the preamp regulation and voltage dropping (there should be much more than 300V on 12ax7 plates?)...anyways, I hope that the bass will be same or tighter with better preamp regulation process. OR is there a change it'll go "mushier" or completely "choked" with the better regulation process.

Btw, the clip was made with a pair of kt88s, played with very low volume and I guess the 273BX tranny was not sagging at all in those circumstances.

So - as a summary - I'm expecting better overall tone in future when using 278CX instead of 273BX. Secondly I'm expecting better overall tone when lowering those Vg2 voltages. Third, I like to think (or hope) that the better regulation in preamp will not cause the preamp boosted speaker resonance go any "mushier".

Mikko