choosing cap values for aikido - 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 24th October 2006, 11:00 PM   #1
jayme is offline jayme  United States
diyAudio Member
 
Join Date: Sep 2005
Default choosing cap values for aikido

My aikido-based preamp has some low-freq resonance in the B+ (probably due its high Q-factor). There appears to be a 0.1V ripple around 12 hertz or so.

Anyways, my question isn't how to fix the PSU...it's how to block it from hitting my outputs.

http://tubecad.com/2005/January/25/Aikido_Amplifier.png

In the above schematic, I have the top cap at 0.1uF as specified in the schematic. Can this be adjusted to deal with B+ resonance?

My output coupling cap is 0.47uF, which gives me a cutoff of ~3Hz. Is the best idea to reduce that to 0.1uF to increase the cutoff to ~15Hz? If I did that, how would I compute the signal dB down point at 20Hz to see how that affects my signal response?

AND...I get a HUGE voltage spike at turnoff...up to 20V on the outputs. Will reducing that coupling cap reduce the output voltage, or is that spike due to the B+ dropping rapidly when the power is cut?


Sorry for all the questions. I'm learning...but slowly...

Thanks,
Jayme
  Reply With Quote
Old 25th October 2006, 01:15 AM   #2
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Quote:
Anyways, my question isn't how to fix the PSU...it's how to block it from hitting my outputs.
Fix the PSU.

Increasing the output rolloff frequency to 15 Hz will well and truly ruin the bass- the phase shifts are very significant.
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 25th October 2006, 02:09 AM   #3
jayme is offline jayme  United States
diyAudio Member
 
Join Date: Sep 2005
Quote:
Originally posted by SY


Fix the PSU.

Increasing the output rolloff frequency to 15 Hz will well and truly ruin the bass- the phase shifts are very significant.
I am working on that....the resonance was 0.4V AC at 15Hz yesterday...so I am improving the PSU...But, I actually learn more about how the signal circuit functions and overall PSU design from my mistakes with the PSU circuit.

Hence, my questions above. They are more for my overall understanding of how the aikido-based signal circuits work, which then helps me refine my understanding and make it better.

Any thoughts? Especially about that first cap that shunts AC noise to the lower half of the output stage...
  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
Help with choosing first kit candi.hansen Multi-Way 2 27th January 2009 11:47 PM
Need help on resistor values for 5687 aikido kit atenolol50 Tubes / Valves 0 24th September 2008 02:00 AM
values of ground(?) coupling caps in Aikido cbutterworth Tubes / Valves 1 31st October 2007 03:53 PM
resistor and capacitor values for Aikido preamp cbutterworth Tubes / Valves 8 26th October 2006 08:21 PM
confusion in the resistor/capacitor values and B+ supply for the aikido jarthel Tubes / Valves 1 23rd May 2006 12:58 PM


New To Site? Need Help?

All times are GMT. The time now is 10:24 PM.


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