Pentode spud...? - 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 27th January 2005, 10:54 PM   #1
Fuling is offline Fuling  Sweden
diyAudio Member
 
Join Date: Aug 2001
Location: Sweden (Mora)
Default Pentode spud...?

Hi

Ive become a bit fascinated by the idea of building a tiny spud (single tube) amp.
The idea of a single active element per channel is interesting and the absense of coupling caps/transformers is also attractive.

Ive seen quite a few schematics showing amps built with WE417, 6C45 and some triode strapped pentodes like E55L and PL802.
What about using a pentode in pentode mode?
I know that the output impedance would be very high unless NFB is applied (and we dont want to do that, right?), but in my particular case this might not be a bad thing.

Nelson Pass has written an article about his experiments with fullrange drivers in BL horns paired with high impedance amplifiers and Im quite inspired by his ideas and results.
My main speakers are BL horns with FE107E drivers and my own tests indicates that they like a bit of output impedance rather than close to 0 ohms.

Ive been looking at quite a few different tubes for this project but high gm pentodes that are linear enough to work without NFB are rare animals.
Today I stumbled across a E280F datasheet and this little critter seems just right for the task.
At 150V plate voltage and 5,6kohm load they will give just over half a watt, pretty much the same as the amp Im using now.
  Reply With Quote
Old 28th January 2005, 11:30 PM   #2
RE 604 is offline RE 604  Germany
diyAudio Member
 
RE 604's Avatar
 
Join Date: Oct 2003
Location: Germany
Hello ,
what about C3m , C3g , D3a , E282F , E810F and EL/PL802 ?
Regards , Alex .
__________________
No reason to get excited : Jimi Hendrix .
  Reply With Quote
Old 29th January 2005, 06:36 AM   #3
Fuling is offline Fuling  Sweden
diyAudio Member
 
Join Date: Aug 2001
Location: Sweden (Mora)
Hello

Probably good tubes all of them, but few of them seems to be locally available at reasonable prices.
Ive already made a deal on three pairs of E280F.
  Reply With Quote
Old 29th January 2005, 07:26 AM   #4
frugal-phile(tm)
diyAudio Moderator
 
planet10's Avatar
 
Join Date: Oct 2001
Location: Victoria, BC, NA, Sol III
Blog Entries: 5
I built a 50EH5 amp (1-1.4W)

http://www.t-linespeakers.org/tubes/SEP_50EH5.html

Click the image to open in full size.

I like it enuff i have a project in the works with much more substantial OPTs... a reader of my site, built this amp up, and having them lying around, substituted a pr of Lundahl 2A3 OPTs into the amp making it a "$405 buck" amp. he said it was quite impressive.

My buddy built this ELL80 amp (the 2nd tube is an EZ81 rectifier), which puts out about 3W (but needs some serious drive (~4V) -- his pre puts out way more than that.

Click the image to open in full size.

dave
__________________
community sites t-linespeakers.org, frugal-horn.com, frugal-phile.com ........ commercial site planet10-HiFi
p10-hifi forum here at diyA
  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
Spud anyone? tubelab.com Tubes / Valves 88 12th January 2010 12:22 AM
Screen Driven Dissimilar Pentode SE Anti-Triode Spud kenpeter Tubes / Valves 2 26th July 2008 02:22 AM
Which Spud Amp? ambience exists Tubes / Valves 0 23rd July 2008 09:43 PM
A small no-fuss pentode/pentode SE amp Tubes4e4 Tubes / Valves 13 1st January 2006 05:16 AM


New To Site? Need Help?

All times are GMT. The time now is 06:22 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