Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

KT77 OPT impedance
KT77 OPT impedance
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 29th September 2011, 05:46 AM   #1
dgta is offline dgta  United States
diyAudio Member
Join Date: May 2011
Default KT77 OPT impedance

Looking at the Genalex KT77 datasheet and for PP UL, it shows Va=500V with Rload =5.5k, then Va=600V with Rload=9k. That's quite a jump.

Question to those who have worked extensively with this tube: can I interpolate? Let's say I have a transformer with 7.2k primary. Can I feed it 550V and be where the tube works best?
  Reply With Quote
Old 29th September 2011, 08:03 AM   #2
artosalo is offline artosalo  Finland
diyAudio Member
artosalo's Avatar
Join Date: Feb 2010
According to my experience in general, the UL connected output stage is not so critical to load resistance. Genalex data is obviously given at optimum point. With lower load resistance the maximum available output power (before clipping occurs) is increased and the distortion level slightly increased too. In case of higer load impedance the situation is opposite. Also the bias adjustment has effect the this situation.

It is also important to notice that the distortion values given at Genalex data are without global negative feedback. So even with a small ( some 10...12 dB) feedback the distortion values are very low.

In reality, the load impedance reflected to output tubes by the speaker load varies between, say 3k...25 k ohms.

So 7.2 k transformer is very suitable for KT77 with 550 V supply voltage.
  Reply With Quote


KT77 OPT impedanceHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
OPT Impedance wdcw Tubes / Valves 7 12th October 2010 11:04 PM
OPT impedance vs. speaker kvk Tubes / Valves 4 16th April 2008 05:37 PM
OPT impedance question Empee Tubes / Valves 10 8th August 2007 01:35 PM
How do I measure OPT impedance? roundel325 Tubes / Valves 1 30th April 2004 07:28 PM
opt impedance camotecue Tubes / Valves 7 27th April 2004 05:47 AM

New To Site? Need Help?

All times are GMT. The time now is 12:28 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio