• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Single Ended Amp Design -- Help Needed

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
hello there
i am trying to design a single ended amplifier based on the kt88 beam tetrode. i have beed told i want about 40 - 45 volts peak to peak input in to the kt88 for optimum performance.

from this i decided to use a 6sn7 for the driver stage, i played about with load lines for the 6sn7 for a while and found a simple common cathode stage using 1/2 a 6sn7 could provide a voltage gain of about 16 which would be perfect to turn a 2.88 pk-pk signal (1Vrms) in to a signal around 45V pk-pk.

is this single stage enough, or should i consider other options to obtain higher gain,,, an srpp based on the 6sn7 for example.

i was wondering about possibly having more gain available at the driver stage for low recording levels on music,

any thoughts?

cheers

soundbadger
 
Search the forum for "Mikael's KT88". It is a single-ended KT88 design that several members have built. It uses 1/2 a 6N1P for the voltage amp. In mine I get between 7 and 8 watts with that schematic. Based on that you should be OK with your setup.

I use my amps (I built them as monoblocks) with CD, tuner, iPod and cable TV and all work fine as sources. I also use a turntable but of course have a phono preamp for that.
 
thanks, but your kind of missing the point.

there are hundreds of amp schematics out there i could build that would work and im sure lots of them are great. i have looked at mikaels amp in detail and even drawn its loadlines to get an idea of its operation. however i am trying to calculate everything myself,,,,
 
Administrator
Joined 2004
Paid Member
The 6SN7 will be adequate with a line stage that has some voltage gain driving it, consider the 6SL7 in SRPP - enough gain to do the job and run at 2mA should provide enough drive to deal with miller capacitance out to 30kHz or so.. (Triode connected, UL not an issue.)

I used 6SL7 in SRPP to drive my cheap and cheerful 45 SE amplifier - it's the oldest amplifier I still own, and sounds good within its limited power capability. Supply voltage to the SRPP would need to be over 300V for best performance.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.