Looks like a promising SE build ?? - 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 21st May 2009, 11:19 PM   #1
diyAudio Member
 
Join Date: Jan 2009
Question Looks like a promising SE build ??

Ok...in my search for a cool higher powered SE build...anyone who's followed my post ... I found this schemo. A couple questions from those of you more knowledgeable then I am. ( That's pretty much EVERYONE...)
1- Where would I insert volume and tone controls...single tone is good...
2- What would the PT need to be rated at ?
3- Any way to eliminate the 2 chokes...or are they pretty commonly available?
As always, thanks in advance...and thanks for all previous help...
Attached Images
File Type: gif 15wtubeamplifier.gif (10.5 KB, 404 views)
  Reply With Quote
Old 21st May 2009, 11:36 PM   #2
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Something is missing around the grid of EL34.
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 21st May 2009, 11:59 PM   #3
diyAudio Member
 
Join Date: Jan 2009
Something...as in what ? Being a fairly novice hobby-type, I need some help from those more familiar with the design aspect.
BTW...Wavebourn, you've been busy today...
  Reply With Quote
Old 22nd May 2009, 12:12 AM   #4
diyAudio Member
 
Join Date: Jan 2009
Question Huh ?

After looking closer at this amp I am very confused. The 845 is a transmitting tube, Right...so what's going on in this amp ? Is the EL34 driving the 845 ??? Where is the rectifier...or power supply for that matter ???
  Reply With Quote
Old 22nd May 2009, 12:16 AM   #5
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Such amps are made to work with the minimal power loss, so output resistance of one stage should match input resistance of another one.
This is the essence of such a straightforward approach. However, some global feedback looks odd here, but it won't hurt. It improves a damping factor, and minimizes distortions that grow with power so loud chords would intermodulate less.


Triodes to work need filament power, B+, and a grid bias. Resistor in cathode is for a bias purpose: when current flows through the tube it creates a voltage drop on the resistor, so if the tube's grid is grounded by DC it sees a negative bias in respect to cathode.
Also, this resistor provides a negative feedback by current, so when tubes consumes more current a voltage drop on the cathode bias resistor increases, and vice verse.

Now, can you tell what is missing? Look at the first stage and compare, if you still don't understand after my explanation...
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 22nd May 2009, 12:16 AM   #6
diyAudio Member
 
aardvarkash10's Avatar
 
Join Date: Mar 2007
Location: Auckland, NZ
Default uuuum, not to belittle you or anything, but

that is one incredibly expensive and (not to put too fine a point on it...) dangerous build for a self-proclaimed novice. 800v operating points are invariably intolerant of unsure hands... Are you sure that you may not be a bit out of your depth here?
__________________
"Folks, you can't prove truthiness with information. You prove truthiness with more truthiness. In a process known as truthinessiness." - Stephen Colbert, The Colbert Report
  Reply With Quote
Old 22nd May 2009, 12:40 AM   #7
diyAudio Member
 
Join Date: Jan 2009
If the grid is negative in respect to the cathode, won't that result in cutoff ?
Expensive is the one word that will keep me from trying his design. I have worked on a couple of Musicman guitar amps that have a B= near the 845, but maybe I'll nix this one. I'm looking for something simpler. The search goes on...
  Reply With Quote
Old 22nd May 2009, 01:22 AM   #8
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally posted by bereanbill
If the grid is negative in respect to the cathode, won't that result in cutoff ?
Thank you.

Forget about this amp, it is dangerous! It may kill
__________________
The Devil is not so terrible as his math model is!
  Reply With Quote
Old 22nd May 2009, 01:38 AM   #9
diyAudio Member
 
Join Date: Jan 2009
Good advice, that...think I'll take it !!!
BTW...any suggestions for a higher powered SE amp ? Something suitable or adaptable for as aguitar amp?
  Reply With Quote
Old 22nd May 2009, 02:47 AM   #10
diyAudio Member
 
Wavebourn's Avatar
 
Join Date: Sep 2006
Location: Pleasant Hill, CA
Send a message via Skype™ to Wavebourn
Quote:
Originally posted by bereanbill

BTW...any suggestions for a higher powered SE amp ? Something suitable or adaptable for as aguitar amp?
Asymmetrical logarithmic amp (one opamp, 3 diodes) driving a very powerful PP amp.
__________________
The Devil is not so terrible as his math model is!
  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
Which of these two kits looks more promising? lurer Multi-Way 0 31st January 2009 06:24 PM
Can I build this? sbcellis Tubes / Valves 6 9th March 2007 12:23 PM
build my first full ranger,let's build another one:a small fullrange high end pc-spea then_dude Full Range 2 30th November 2005 07:54 AM
Do i need to build main supply (240v) filter?Or build power distribution? thomgun_lc Chip Amps 9 16th September 2005 09:52 AM


New To Site? Need Help?

All times are GMT. The time now is 08:41 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