RS1003 in SE triode-UL monoblocks - Page 5 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

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

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
Reply
 
Thread Tools Search this Thread
Old 23rd June 2012, 11:14 AM   #41
tcqanh is offline tcqanh  Viet Nam
diyAudio Member
 
Join Date: Apr 2011
Location: HoChiMinh city
Quote:
Originally Posted by davorin View Post
You need drive tube with internal resistance less than 1,8kOhms.(18/10 kOhms)
you mean 1.8k is Zout or Ri of tube driver stage ?

my 6AQ5 has 1.9k Ri at triode connection, but its gain is a bit low 9.5. So I need one input stage.

the tube with high gain and high transconductance and low resistance so far.... is expensive . only 6C19, 6C45P is still quite cheap, but I don't like their aggressive sound.

Do you have a equation of calculating Ri at triode connection for penthode tube ? (when we have no information of Ri in triode connection from datasheet)

Last edited by tcqanh; 23rd June 2012 at 11:34 AM.
  Reply With Quote
Old 23rd June 2012, 11:14 AM   #42
davorin is offline davorin  Croatia
diyAudio Member
 
Join Date: Aug 2005
Location: Zadar, Croatia
All of that trodes are very good (linear, very low internal resistans), but gain (real) is low, and You need 2 stages!
E810F/7788 (no E801F) is excellent tube, and gain is ~28x, EF184/6J7 with gain 28x, E180F/6688 wth gain 29x, 12HG7 with gain 24x, 11HM7 with gain 24x are all perfect!
Also russian 6S45P-E triode is very good with gain 25x (Ua=400V, Rk=100 Ohms NO-baypass and Rload=10kOhms), and very low distorsion and linear caracteristic.
  Reply With Quote
Old 23rd June 2012, 11:19 AM   #43
davorin is offline davorin  Croatia
diyAudio Member
 
Join Date: Aug 2005
Location: Zadar, Croatia
Quote:
Originally Posted by tcqanh View Post
my 6AQ5 has 1.9k Ri at triode connection, but its gain is a bit low 9.5. So I need one input stage.

the tube with high gain and high transconductance and low resistance so far.... is expensive . only 6C19, 6C45P is still quite cheap, but I don't like their aggressive sound.
6S45P-E have not "aggressive" sound with NO-BAYPASS katode resistor!
  Reply With Quote
Old 23rd June 2012, 11:38 AM   #44
tcqanh is offline tcqanh  Viet Nam
diyAudio Member
 
Join Date: Apr 2011
Location: HoChiMinh city
Quote:
Originally Posted by tcqanh View Post
I did use some low resistance tube, like E801F with Ri about 1K in triode connection,
confused

E810F = 7788 with approximate 1K of Ri
  Reply With Quote
Old 23rd June 2012, 11:49 AM   #45
tcqanh is offline tcqanh  Viet Nam
diyAudio Member
 
Join Date: Apr 2011
Location: HoChiMinh city
Quote:
Originally Posted by davorin View Post
6S45P-E have not "aggressive" sound with NO-BAYPASS katode resistor!
OK, I will try this method and compare E810F vs 6S45P with no bypass.

what difference of bandwidth in case of bypass capacitor or without bypass ?

I feel having loss some low frequencies, thin sound, a bit less dynamic without bypass cap (specially high value Rk>1-2k) but I don"t know why. so using this cap is routinely for me

Last edited by tcqanh; 23rd June 2012 at 12:05 PM.
  Reply With Quote
Old 23rd June 2012, 11:52 AM   #46
tcqanh is offline tcqanh  Viet Nam
diyAudio Member
 
Join Date: Apr 2011
Location: HoChiMinh city
Quote:
Originally Posted by davorin View Post
6S45P-E have not "aggressive" sound with NO-BAYPASS katode resistor!
for your experience, when do you take place bypass kathode ?
  Reply With Quote
Old 23rd June 2012, 02:52 PM   #47
davorin is offline davorin  Croatia
diyAudio Member
 
Join Date: Aug 2005
Location: Zadar, Croatia
Quote:
Originally Posted by tcqanh View Post
for your experience, when do you take place bypass kathode ?
6S45P-E was originaly construckted for VHF-UHF high gain amplifier
With baypass capacitor(s) increase gain at very high freqence (>50MHz) and tube easy go to short "ringing" (self-oscilacion) at peak level of input audio signal. If You have osciloscope or spectral analizator with 200 or more MHz bandwith, You can easy see "overshoot" at begening of every start test sqere signal (only at high level part of signal). This "overshoot" moved tube working point, and increase gain in very small part of interval, or put tube in self-oscilating when input audio signal is in peak. That result with short expanding of audio signal, or You hear it "aggressive".
Without baypass capacitor, gain at very high freqences (VHF-UHF region) decrase, and tube work all time in linear region. You can stoped oscilation ("ringing","overshoot") with neutralization, very shot wires of components, more blocking capacitors (at heater wires especialy!), soldering parts directly at socket, using "feritte-roads-pearls", etc.
All tubes with high transconductance have more/less simmilar problems like 6S45P-e (E810F also!).
  Reply With Quote
Old 24th June 2012, 03:24 PM   #48
tcqanh is offline tcqanh  Viet Nam
diyAudio Member
 
Join Date: Apr 2011
Location: HoChiMinh city
Quote:
Originally Posted by davorin View Post
All tubes with high transconductance have more/less simmilar problems like 6S45P-e (E810F also!).
I've got this problem when I've been exchanged Plate choke load (high gain) to Rload (low gain ) with E810F. Sometimes, I can hear the treble that has overcut or distortion.

but, we can get low impedance with C bypass. It is definitely a advantage for the driver stage. Without C bypass, internal resistance will be increased significantly. remember that all of Ri in datasheet of any tube is from measuring tube in case of doing C bypass.
  Reply With Quote
Old 24th June 2012, 03:57 PM   #49
diyAudio Member
 
Join Date: May 2007
Quote:
I must use SHADE-feedback to reduce gain and distorsions.
Hello Davorin,
F3a/RS1003 is a great tube and your amp looks nice. But with your Schade implementation you will increase distortion radically. A triode with bypassed cathode isn´t the best solution. If you want it to work, you should go for unbypassed cathode and pentode-connected EL83 driver. This will probably reduce distortion two to four times wrt triode-strapped driver. If you insist on triode-strapping and UL you must remove the cathode cap to lessen distortion somewhat but it will still be very high.

Last edited by revintage; 24th June 2012 at 04:08 PM.
  Reply With Quote
Old 24th June 2012, 05:18 PM   #50
diyAudio Member
 
the_manta's Avatar
 
Join Date: Nov 2006
Location: Munich, Bavaria
Remove cathode decoupling in the output stage ? Say hello to current feedback, sluggish sound, (1+µ)*Rk times lesser damping and wimpy bass response.
Additionally, the fact that this so called Schade-feedback isn't really great in distortion reduction has been discussed here a few times already. But, to each his own
__________________
Терпенье и труд все перетрут
  Reply With Quote

Reply


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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Triode VS. UL bias gtrmkr Tubes / Valves 5 2nd May 2011 09:35 PM
UL - triode switch torrence Tubes / Valves 2 7th July 2008 09:58 AM
converting UL in triode overdrajv Tubes / Valves 11 25th December 2007 05:21 AM
UL to triode kathodyne Tubes / Valves 55 21st August 2005 09:05 PM


New To Site? Need Help?

All times are GMT. The time now is 03:38 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2