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

Octal Preamp Triode Thoughts (IDHT's)
Octal Preamp Triode Thoughts (IDHT's)
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 16th August 2013, 02:09 PM   #1
rcollege is offline rcollege  United States
diyAudio Member
Join Date: Dec 2010
Default Octal Preamp Triode Thoughts (IDHT's)

I'm building a preamp using a very basic SE design to drive a Dynakit ST35.
It has an input impedance of 500K. My main source has a 200mV RMS output...so I will need some gain to bring it to 1V RMS.

Any thoughts about using a 6K5gt for a preamp or phono stage? Mu of 70.
I also have a 7F7 (double triode) and access to more- Mu of 70.

Also any thoughts of 6C5g's vs. 6J5gt's? Are they too close to warrant changing from one to another?

Any thoughts on other IDHT octal triodes would be awesome- especially single triodes.


Last edited by rcollege; 16th August 2013 at 02:11 PM. Reason: Grammar
  Reply With Quote
Old 16th August 2013, 03:02 PM   #2
kevinkr is offline kevinkr  United States
diyAudio Moderator
kevinkr's Avatar
Join Date: Sep 2004
Location: Boston, Massachusetts
Octal Preamp Triode Thoughts (IDHT's)
Both 6C5 and 6J5 would be an excellent choice for a simple line stage. See which you like best.
"To argue with a person who has renounced the use of reason is like administering medicine to the dead." - Thomas Paine
  Reply With Quote
Old 16th August 2013, 04:01 PM   #3
Eli Duttman is offline Eli Duttman  United States
diyAudio Member
Join Date: Apr 2004
Location: Monroe Township, NJ
You mentioned the Loctal 7F7, which is electrically equivalent to the Octal 6SL7. An interesting Loctal medium mu twin triode is the 7AF7. The advantage of this type is its 300 mA. heater draw. The 7AF7 makes a fine common cathode voltage amplifier. However, its relatively low gm is a warning against cathode follower service.
Eli D.
  Reply With Quote
Old 16th August 2013, 05:41 PM   #4
Vinylsavor is offline Vinylsavor  Germany
diyAudio Member
Vinylsavor's Avatar
Join Date: Feb 2002
Location: Lindau

Is this for a line stage or phono or both?

In terms of high mu octals I like the 6SF5:

VinylSavor: Tube of the Month : The 6SF5

and the 6SC7 (both sections paralleled):

VinylSavor: Tube of the Month: The 6SC7

I used both of these in phono stages with success.

For line stages I like the 6AH4:

VinylSavor: Tube of the Month: The 6AH4

Bets regards

  Reply With Quote
Old 16th August 2013, 08:31 PM   #5
rcollege is offline rcollege  United States
diyAudio Member
Join Date: Dec 2010
Thanks for your responses.

Just picked up a pair of 6J5GT's for $6.50ea.

Has anyone tried the 6K5G in a phono stage...or any audio?
It has a high Mu...low heater current draw (0.3amps). It's curves look good- if I'm looking at them correctly.
I tried it in a line stage with a clean response...more in the highs...but I'm interested in others' comments and or experiences.
  Reply With Quote
Old 29th March 2015, 08:06 PM   #6
alexkhar is offline alexkhar  Russian Federation
diyAudio Member
alexkhar's Avatar
Join Date: Mar 2015
Location: Moscow
Octal Preamp Triode Thoughts (IDHT's)
I use 6K5GT as driver in SE Amp. Ua=230V, Ia=1,17 mA. Sound is very clear so I like it.
  Reply With Quote


Octal Preamp Triode Thoughts (IDHT's)Hide 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
Akita 12V preamp thoughts prezden Tubes / Valves 13 23rd August 2013 02:00 PM
Aikido Octal Preamp Glassware TCJ with regulated supplies mattattnet Swap Meet 1 4th October 2011 02:05 AM
hybrid amp with dht or idht inputs? AudioGeek Tubes / Valves 0 1st January 2011 04:04 PM
thoughts about a 'universal' preamp ErikdeBest Tubes / Valves 16 30th March 2010 08:56 PM
I want to build a preamp for my dad.. thoughts? 240z4u Tubes / Valves 32 22nd April 2009 01:32 AM

New To Site? Need Help?

All times are GMT. The time now is 04:49 PM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.79%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio