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I have just built a P1 eXtreme with a KT88 for a bit of fun, I have been piling in filter caps to try and take advantage of the KT88s power handling so I have a piggy-backed set inside a la Wreck and a can on the outside. Sounds pretty good and thanks to the MV I can get some great pre-amp gain without blowing my ears off. Not sure if I like the KT88 as much as a EL34 or a 6L6 though, it sounds a bit wooden to me, I may try some different tubes in there later. I'll try and get some clips done, it is quite Plexi ish. I did try referencing the 6.3V CT to the cathode of the KT88 to solve a hum problem but that made no difference so I sliced my bus bar after the power caps and grounding them seperately and ended up dead quiet.
Nigel

http://www.kirkby.com.au/g2/main.php?g2_itemId=680

Man that's a lot of iron for a SE low power amp! What would make such an amp desireable to me would be one that accomodates a whole raft of power tubes. Are you considering that by any chance?

Interesting on the grounding. I always split the power end from the preamp end.

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

The OT is a Hammond 125E clone, a bit large granted but what I had on the shelf. This is a bit of an experiment with the KT88, the amp will take just about any octal tube so I will try a few different combinations. It was destined to be ripped apart and built into something more permenant but I kind of like it, you can dial up a fair amount of gain without the volume. I might stick one of Eddies reverb/tremolo combinations in it to see how it goes.
Nigel

What about a 9 pin socket for the little guys?

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Stephen
Web: www.trinityamps.com. Facebook: facebook.com/trinityamps. Twitter: @trinityamps

Nigel,

I had been toying with the same idea, just hadn’t quite figured out how to do the tremolo yet. I built a hi-octane/eXtremee amp for my buddy (the one in my avatar) and was very impressed with the output of the sucker. I have it set up to take most of the octal tubes, although I don’t know if it would handle a KT88

Eddie

Well I have a few 9 pin type holes cut in that chassis so it would not be a hard job, the P1 was originally 1 X 12AX7 and 1 X EL84 so I guess it would be a small change. It would then make a great test bed for both pre-amp and power tubes.

Eddie, in the eXtreme if your iron is up to it, it is only the cathode resistor changed to run a KT88 I'm using a 220R 5W, I think the tube sucks 90mA. Then you have got a few bucks to pay for the KT88 I have been playing it a lot today and it is growing on me.
Nigel

Nigel,
How did you settle on the P1X vs say the HO? I have been wavering between these two with either an el-34 or KT-88 output. I have a Hammond 125FSE and a big beastly PT left over from another project (one of Sarge's SE moviola's) that should work quite nicely. I was also thinking about playing with Dana's or KoC's variable B+ for low volume playing. What do you think, P1X or HO?
Broz

If you shoot over to 18w.com and ask phil himself, he will tell you that the HO is largely designed for preamp grind...while the P1eX, is more designed to yank the goods from the power tube....when I do get around to building one of these, it will most definitely be a P1-ex for that point alone.

As far as adding a 9-pin for the little bottle, I wouldn't bother. That only affords you more option. You're far better off creating a switching mechanism that switches out various cathode resistors, so that you can try a whole slew of big bottles...i.e. el34, 6l6, 6v6, kt88, 6550, etc, etc

Frankly, a single ended el34 amp with Bass, Middle, Treble, volume and enough gain for me to go into orbit is just about perfect for me....and to hell with the other options..



-Frank

Broz, the thing I liked about the P1x was the range, you can get some nice clean out of it as well. Phil was obviously a draw card as he frequents just about every board and you can always catch him at question time. I am considering putting a second pre-amp tube in it as per the variable cascode boosted schematic.

Frank, I am going to chuck an EL34 in there today, I will let you know what it sounds like.

Nigel

Here is a crap little clip I did where I compare two tubes, if your stereo is correct the KT88 is left and the EL34 is right. Scuse the sloppy playing.
Nigel

http://www.kirkby.com.au/g2/main.php?g2 ... 0e733ca979