EAR 859 questions - Page 4 - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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
Thread Tools Search this Thread
Old 11th February 2004, 11:19 AM   #31
AV8R is offline AV8R  United Kingdom
diyAudio Member
Join Date: Feb 2004
Location: Cambridge
Default Output impedance calculations 4.6K

How I know is by measuring actual amp of 859. To measure disconect transformer from circuit and apply a 1 KHz oscilator to primary and check at the terminal that you have 1 volt then with the same milli-voltmeter measure the 8 Ohm tap and you will see 41.7 millivolts.which is 23.98:1 squared is 575 times 8 = 4600 Ohms.
Secondly the voltage accross cathode resistor corresponds to about 80 MA.

Without measuring equipment you are guessing in the dark.
  Reply With Quote
Old 23rd February 2004, 05:43 PM   #32
nonos is offline nonos  Hungary
diyAudio Member
Join Date: Jan 2004
Location: szhely
Default Ear 859 output transformer

Hi AV8R,

Thank you very much your information ! You helped a lot !


Did you find the article?

  Reply With Quote
Old 23rd February 2004, 07:07 PM   #33
qwad is offline qwad  Australia
diyAudio Member
Join Date: Mar 2003
Location: adelaide city of churches
sorry, but I am all tied up at the moment with renovation of the kitchen/ bathrooms and painting though it is on my mind... its just a matter of finding the time to sit down and babrálni a számolo gépemmel és a skannerrel, nagyon bocsánatot kérek, de nem felejtettem el... szia tamás
we all have problems only some people have more than most....
long live the Magyar (Hungarians) in the world!
  Reply With Quote
Old 5th March 2004, 08:45 PM   #34
diyAudio Member
Join Date: May 2002
Location: Madison, WI
I have some dim recollection of TDP claiming that there was intentional mis-identification of some of the component values of this amp in the published schematic, presumably to thwart attempts to DIY this amp. Does anyone share that recollection? - Pat
  Reply With Quote
Old 5th March 2004, 11:49 PM   #35
dhaen is offline dhaen  Europe
diyAudio Moderator Emeritus
dhaen's Avatar
Join Date: Jun 2002
Location: U.K.
Default Thwartment......

Ask him!

In any case, DIY'ing a production amp is impossible without sourcing the original iron.
Different iron = different amp.
  Reply With Quote
Old 27th October 2005, 11:47 AM   #36
drobert is offline drobert  Hungary
diyAudio Member
Join Date: Jul 2005
Location: Szombathely
Hello AV8R!

Can you take any photo about this amplifier? (EAR859) I like to know what is the inside of this amplifier.

  Reply With Quote
Old 20th November 2005, 12:11 PM   #37
Fuling is offline Fuling  Sweden
diyAudio Member
Join Date: Aug 2001
Location: Sweden (Mora)
I´ve built a pair of monoblocks quite similar to this amp.
PC86 input stage RC-coupled to an IRF820 Mosfet driver that feeds the screen grid of the output tube.
I guess the input stage could be direct coupled to the mosfet, but I´m slightly paranoid about drifting bias and tube ageing.

In an previous version I used a 6SN7 mu-follower direct coupled to a 12B4A cathode follower, worked like a charm but it was a mess to wire up with three triode sections
  Reply With Quote
Old 20th November 2005, 01:03 PM   #38
Ardee is offline Ardee  England
diyAudio Member
Join Date: Nov 2005
I made an EAR 859 many years ago when the design was published in Hi-Fi News and you could buy the iron from Yoshino. It was an amazing amp, and I still haven't heard an SE amp I like better. If jazz or classical is your thing, build it. Tim de Paravicini is justifiably secretive about his transformer designs, but I think the output transformers were about 6K8 impedance. They had Tim's usual complicated winding structure, so I wouldn't expect others to perform anything like so well. Note that the 47pF capacitors shown connected to the anode are probably the wrong value - try 4.7pF unless you want a very rolled off top end. If you don't use the proper tranformers, you'll have to experiment with the feedback components anyway.

I have a feeling that many people bought the ironwork for this amplifier but never got round to building it, so it might be worth trying some want ads.
  Reply With Quote
Old 20th November 2005, 02:24 PM   #39
Fuling is offline Fuling  Sweden
diyAudio Member
Join Date: Aug 2001
Location: Sweden (Mora)
I use Hammond 1627SE (2,5K 25W) in my monoblocks.
According to Svetlanas plate curves I´d rather use 5k transformers, but 2,5k was what I had.
My prototype had OPT´s from an old Edisons 60 wired as 5,6k.
  Reply With Quote
Old 20th November 2005, 04:05 PM   #40
Ardee is offline Ardee  England
diyAudio Member
Join Date: Nov 2005
2k5 sounds rather on the low side to me. Driving the screen gives nice triode curves but a pentode output impedance, hence the need for feedback!
  Reply With Quote


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
Some Quad els57 questions! - Novice Questions! Fanuc Planars & Exotics 13 5th December 2007 09:26 AM
PSU for QSC amp questions rkc7 Parts 5 10th November 2005 05:18 PM
Last questions about this Madmike2 Multi-Way 9 13th June 2005 11:12 PM
Questions, questions, from newb DIYer Phatman91624 Multi-Way 41 3rd August 2002 02:52 AM

New To Site? Need Help?

All times are GMT. The time now is 06:26 PM.

vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2