We have liftoff!!!! Houston, all systems are go! - 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 May 2004, 08:40 PM   #1
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Default We have liftoff!!!! Houston, all systems are go!

After agonizing over parts and biasing and countless PSU simulations I am enjoying sweet success with my new SE 5687/EL34 amp. Diana Krall is crooning in my ear as we speak and she is sounding quite lovely. I can also say that the Magnequest transformers (TFA-204s) are proving to be every bit as good as their reputation alleges. I will post pics and schematics as soon as I can tear myself from my listening position long enough. Cheers.
__________________
Gavin
  Reply With Quote
Old 24th May 2004, 08:45 PM   #2
diyAudio Member
 
Join Date: Jan 2003
Location: Sweden
Very nice to hear. I still remember the first time I got my amp up and running. The sweetest sound imaginable gently flowed from my speakers. There truly is something very special about tubes.
  Reply With Quote
Old 24th May 2004, 10:42 PM   #3
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
The longer it plays the better it gets!! I am a believer of a choke in the PSU now. The difference is readily apparent. The EL34 sounds nice in SE triode mode. Very punchy and smooth. It purrs!!!!
__________________
Gavin
  Reply With Quote
Old 25th May 2004, 02:02 AM   #4
diyAudio Member
 
Join Date: Apr 2004
Location: Monroe Township, NJ
Quote:
I am a believer of a choke in the PSU now.
G.,

It can get better. Try a choke I/P filter some time. Reasonably tight regulation with little fuss.
__________________
Eli D.
  Reply With Quote
Old 25th May 2004, 02:05 AM   #5
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
What exactly is a choke I/P filter? I may just incorporate one into the amp.
__________________
Gavin
  Reply With Quote
Old 25th May 2004, 02:14 AM   #6
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
Hey-Hey!!!,
Choke input, instead of a Pi-symbol looking arrangement of a capacitor, choke and capacitor, the choke is directly connected to the rectifier's cathode(s).

Requires a minimum curent drawn to operate properly, and this is dependant on input voltage and the choke's inductance.

The output voltage is about .9 times the RMS input voltage and less the resistive losses in the copper coil and drop across the diodes if tubes are used.

Benefits are a constant load on the power transformer, as the choke passes DC and presents an impedance to AC. Since the Harmonic content of a half of a Sine wave has a DC content of magnitude ~90% of the RMS value, this is what the choke seeks to output. The resulting AC component is at 120 cps and is also a sine wave. Sine waves are fairly easy to filter out with energy storage devices like capacitors ( and Inductors for that matter...).

Anyway, there are many details that I went over with only a bare mention, look to follow-ups and ask more questions.
regards,
Douglas
__________________
the Tnuctipun will return
  Reply With Quote
Old 25th May 2004, 02:36 AM   #7
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Thanks Bander. I'll do some research on it.
__________________
Gavin
  Reply With Quote
Old 25th May 2004, 05:20 AM   #8
arnoldc is offline arnoldc  Philippines
diyAudio Member
 
Join Date: Apr 2003
Location: Makati
Send a message via Yahoo to arnoldc
hi g, is this PP, SEP, or UL? PPP? can i pull you out of your listening chair?

btw, you remind me of holy man
  Reply With Quote
Old 25th May 2004, 05:13 PM   #9
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Quote:
Originally posted by arnoldc
hi g, is this PP, SEP, or UL? PPP? can i pull you out of your listening chair?

btw, you remind me of holy man
I apologize. THe sound and the alcohol prevented any further transmissions. It is a SE EL34 amp using a 5687 as the driver. It is triode strapped using no feedback. The output transformers are Magnequest TFA-204s. The rectifier is a GZ34. I will draw up an "as built" schematic with the part numbers listed. I'll even try for a pic or two but I may have to have someone host the images as I don't think I can get it to upload to the site due to the resolution. As far as being Holy goes I'm afraid you have the wrong guy. I have been accused of much worse though. So thanks. I think.

__________________
Gavin
  Reply With Quote
Old 25th May 2004, 07:03 PM   #10
G is offline G  United States
diyAudio Member
 
G's Avatar
 
Join Date: Apr 2002
Location: Belleville, IL.
Here is the schematic of the amp "as built". The biasing of the 5687 isn't optimal as I'm dropping more voltage across the plate resistor than I am the tube itself. I ended up with the grid at -6 volts. I was aiming for -7. Go figure.
Attached Images
File Type: gif se el34 (small).gif (14.1 KB, 184 views)
__________________
Gavin
  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
Houston, We Have A Problem....... cwoodall Parts 12 13th September 2005 04:31 AM
New member from Houston,TX vidasean Introductions 1 8th August 2005 04:28 PM
Hello from Houston, Texas! mista2 Introductions 9 23rd April 2005 05:43 AM
Intro from Houston soundsgoodtome Introductions 2 2nd November 2004 04:27 AM
Houston,we have problem... Upupa Epops Solid State 47 10th October 2004 01:02 PM


New To Site? Need Help?

All times are GMT. The time now is 12:45 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