• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join freeLog in
    Want zero display ads or expanded classifieds tools? Compare plans.

schematic for kt88 power amp

Here is what I built.

I put this 70's era Hiwatt Pre-amp

http://mhuss.com/Hiwatt/Schematics/DR_Pre4Input_v2.pdf

and mated it to this Sound City power supply and power amp section, which is very close to the Hiwatt 4xkt88 power amp.

[This invalid link has been removed]

I did it this way because I already had the Sound City amp and just wanted to change the pre-amp. I completely rebuilt the power amp though so it's new except for the transformers.

This combo sounds so amazing for bass it's almost hard to describe. It's like a hi-fi solid state amp combined with a bad ass tube amp. It can do perfect crystal clear cleans and gets a little dirty when you crank the gain up

Good luck and have fun.
Be careful of the high voltage, you need some serious juice to get 200 watts out of 4xKT88's. Mine has a plate voltage of 730V
 
Heater current is a consideration I think we should look at.
also the KT 88's are different to 6550's and require different output transformer impedance for best matching.
Its hard to make a Hiwatt DR 201 4 X KT88 clone for less money or any better than Webber, maybe if you started with an old Simms Watts, Carlesbro or Sound City 200 you would save alot if the transformers and coke where OK but what's your time and burnt fingers worth even if you don't get across the plate voltage.:D
 

Latest posts