New Schematic Linestage Tube Preamp using EF86 & 12AX7 - Page 5 - 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 24th January 2012, 09:44 AM   #41
Edwind is offline Edwind  Indonesia
diyAudio Member
Join Date: Jan 2012
Thanks for the answer DF96.
I don't know how to create a model and simulate the schematic that I post and Lars.
Just want to know what exactly happened with that two circuit.
Maybe Lars can help?
  Reply With Quote
Old 24th January 2012, 09:49 AM   #42
SY is offline SY  United States
On Hiatus
SY's Avatar
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 2
If this circuit gave you distortion and rolled off highs, then you have likely made a mistake somewhere in the construction (or elsewhere in your signal chain) and need to hunt that down.
"You tell me whar a man gits his corn pone, en I'll tell you what his 'pinions is."
  Reply With Quote
Old 24th January 2012, 10:05 AM   #43
Edwind is offline Edwind  Indonesia
diyAudio Member
Join Date: Jan 2012
I've been checked more than 3 times.
Last Sunday, I also called my friend to come.
He checked again (found no mistakes) and did a blind test (I build a new one for Lars's circuit).
I used the same quality, marks, and types components but with different values for resistors.
The result are the same with me.
So I guest the answer must be THD, harmonics number, etc.
  Reply With Quote
Old 24th January 2012, 10:48 AM   #44
DF96 is offline DF96  England
diyAudio Member
Join Date: May 2007
The circuit is sufficiently simple that if properly built with the right value components it can't really go wrong. The volume control at the input will ensure it can handle any source, and there isn't really anything in it to roll off the treble. My conclusion is that either you haven't built what you/we think you have built, or you are not using it in the way you/we think you are using it.
  Reply With Quote
Old 24th January 2012, 11:20 AM   #45
diyAudio Member
Join Date: May 2007
So, how does the rest of your signal chain look? Something is wrong, but not in the lineamp, if you have built it according to the schematic.
  Reply With Quote
Old 24th January 2012, 12:10 PM   #46
Edwind is offline Edwind  Indonesia
diyAudio Member
Join Date: Jan 2012
I agree with DF96, we maybe have different assumptions.

I connect it directy to power amp by RCA interconnect cables. Just like usual, no other equipment such as line selector or passive pre-amp, etc.

By the way, I remember 3 years ago (or more) when I still not an audio-holic my friends said if I can heard loud differences as low as ±0.5dB or lower.
I don't know true or not what they said until now.
But, is it influent in my opinion "it's seem already roll of at 15kHz"?
  Reply With Quote
Old 24th January 2012, 01:10 PM   #47
diyAudio Member
Join Date: May 2007
You didn´t mention your source?

Measure and you will find that -3dB is at a few hundred kHz and THD, with mainly 2nd order harmonics, is far below 0,1%.

You found your previous design was low in distortion, and it is very far from!

So the only thing I can think of, is that your preferences maybe are a bit off as this one should be close to invisible. Could the loss at 15k be the absense of distortion?

Please report back when you have found/built something that suit you needs.

Last edited by revintage; 24th January 2012 at 01:17 PM.
  Reply With Quote
Old 24th January 2012, 02:17 PM   #48
Edwind is offline Edwind  Indonesia
diyAudio Member
Join Date: Jan 2012
Sorry I forgot, the source was CD-Player (NAD C-542).
As I wrote before, I don't have any measurement instruments.
Just LCR + multimeter only.
That's why I couldn't tell the value of THD, harmonics number, IMD, freq. response, crosstalk, phase shift, open and closed loop gain, input and output impedance, etc.
What I need is sound reproduction must as natural as possible to real sound, not only depending on instruments measurement values or theoretical calculation on paper/simulation.
Since there are a lot off stuff has 0.01% of THD on 1kHz, but all sound different one from another.
Any way all of you already help me as far as this time.
I'm very proud.
Thanks everybody.
  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
Cascode Tube Mic Preamp: 12AX7/12AU7 Schematic 88man Tubes / Valves 13 4th August 2012 12:08 AM
converting EF86 to take 12AX7 vintage_dog Tubes / Valves 25 5th May 2011 04:36 PM
EF86 tube preamp gaborbela Tubes / Valves 2 10th February 2010 07:00 PM
12AX7/12BH7 Hammond Tube Preamp Project jordankersten Tubes / Valves 4 5th April 2009 02:49 AM
suitable preamp for a tube amp (kt88+12ax7) kevinkuang Tubes / Valves 6 17th March 2005 02:22 PM

New To Site? Need Help?

All times are GMT. The time now is 03:28 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