WAD KT88 Schottky and pi filter mod for LT supply

[rgccarter]

Just purchased a 2nd hand KT88 off fleabay, to upgrade - had a KEL84 for 12years which has been extensively modded but time for a new project


As the title says, can anyone point me to directions for schematic, build instructions, parts list to do this mod on a KT88?

know its on WD88VA as an XL upgrade - but would this be applicable to the KT88?

Thanks

[bob orbell]

Yes, but I doubt you will hear any difference, did it to my WA88, but it was a pointless exercise. I got better results from low ESR capacitors on the HT line. Bob

[Richard]

Originally Posted by rgccarter

Just purchased a 2nd hand KT88 off fleabay, to upgrade - had a KEL84 for 12years which has been extensively modded but time for a new project


As the title says, can anyone point me to directions for schematic, build instructions, parts list to do this mod on a KT88?

know its on WD88VA as an XL upgrade - but would this be applicable to the KT88?

Thanks

Hello and welcome,


If yours is Kit88 the FAQ is here,


http://www.world-designs.co.uk/forum...ead.php?t=7644


I did it to mine and wrote it up along with the results. There was a measurable and audible improvement

[Richard]

Originally Posted by bob orbell

Yes, but I doubt you will hear any difference, did it to my WA88, but it was a pointless exercise. I got better results from low ESR capacitors on the HT line. Bob

If your amp is an WD88VA variant then all you need is the circuit diagrams for WD88VA and WD88VA XL to compare to yours and work to. Drop Greg a PM to see if he can send them to you. Peter Comeau used this modification to improve the heater suppy in the tweaked XL version.

[Matthew Snell]

Just for information, it gets my vote. You may not "hear" any difference, but the amp will be technically better. Of course you MAY even "hear" a difference.

Not trying to sell anything - although the parts are here (as well as being available elsewhere).

Also, Bob is right about the HT caps. Did you bypass the caps, Bob, as we do in the current KT88 XL?

Matthew

[bob orbell]

No Matthew, I did not by-pass any capacitors, what I understand from books, by-passing PSU capacitors is a little more complex than just adding a smaller capacitor to the main capacitor, the connections must be made not at the main capacitor but at the load end and 0 volt line, this would have meant a lot more wire. If I am wrong about this, please correct me. Bob

[bob orbell]

Richard, -- Peter Comeau used this modification to improve the heater supply in the tweaked XL version. -- of course, a regulated supply would be better, but I doubt many would hear any improvement. It is the HT supply to the valves that produces a better sound. Bob

[John Caswell]

Please define "Better"

John

[bob orbell]

I think we have been here before John, OK, more refined a touch more detail and less harsh, I hope that helps . Bob

[rgccarter]

Originally Posted by Richard

If your amp is an WD88VA variant then all you need is the circuit diagrams for WD88VA and WD88VA XL to compare to yours and work to. Drop Greg a PM to see if he can send them to you. Peter Comeau used this modification to improve the heater suppy in the tweaked XL version.

Thanks that's great. The amplifier arrived today, but I don't have a CD-ROM drive so instructions would be helpful anyway.