Amplifier with a sound. How to build for second harmonic. - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 17th November 2012, 09:21 AM   #21
lineup is offline lineup  Sweden
diyAudio Member
 
lineup's Avatar
 
Join Date: Dec 2005
Location: the north
Thank you RJM1.
Can you comment a bit what your circuit does
and how and why it works.

These guys with electric guitars have done this for ages.

Also thanks to jerluwoo.
I will try your circuit.
__________________
lineup
  Reply With Quote
Old 17th November 2012, 09:37 AM   #22
RJM1 is offline RJM1  United States
diyAudio Member
 
Join Date: Jan 2010
Location: Titusville, Fl.
The three transistors each amplify signal and their output is 180 degrees out of phase with the input (plus some delay). this signal is added to the input signal which cancels most of the fundamental. The signal is then amplified by the op-amp to give approximately the same output level as the input with greatly increased distortion products.
(Vin -(Vin + distortion))* gain = output
  Reply With Quote
Old 17th November 2012, 10:11 AM   #23
RJM1 is offline RJM1  United States
diyAudio Member
 
Join Date: Jan 2010
Location: Titusville, Fl.
R14 should be replaced with a 360 ohm resistor and a 100 ohm pot. Adtust for minimum output.
  Reply With Quote
Old 17th November 2012, 10:33 AM   #24
Jay is offline Jay  Indonesia
diyAudio Member
 
Join Date: Feb 2003
Location: Jakarta
Quote:
Originally Posted by wahab View Post
Use an input differential with a poor current source , typicaly a resistor connected to a zener voltage reference.
Yes, we can add distortion to produce a "favorable" sound. But distortion is distortion, whatever the order.

But when distortion is already adequately low, then I'll pay attention to the harmonic structure. I.e. not wanting even extremely lower THD by sacrificing harmonic structure.

The "poor" ccs as posted by wahab, will create good harmonic structure but the distortion is intolerable. But it has one merit. When the circuit has poor stability, I will check if that ccs will solve my problem.

Depend on circuit, higher bias will tend to bring not only lower distortion, but also good harmonic structure. So I always check if adding only a few hundred mA will turn the structure positively.

In a bootstrap circuit, a feedback usually connected to the middle of 2 resistors. Connecting the feedback (e.g. the bootstrap cap) closer to the positive rail (instead of to the transistor base) will augment the second order. So 3K3/3K3 can be replaced with 2k2/4k4 or even 1k5/5k1. Usually I use no higher than 3K3 towards the positive rail.
  Reply With Quote
Old 17th November 2012, 10:55 AM   #25
Jay is offline Jay  Indonesia
diyAudio Member
 
Join Date: Feb 2003
Location: Jakarta
Default Choice of parts (transistors)

Parts (transistor or opamp) are usually famous for good sound when they tend to produce good harmonic structure, or augmented second order.

When a device tend to produce higher odd order, usually it is very hard to lower the 3rd order so to make a good monotonic structure. But when the device tend to give augmented 2nd order, it is usually easy to lower all of the distortions, or to make a good harmonic structure.

Darlingtons have terrible harmonic structure that it has a reputation for a bad sounding device. Motorola MJ11015 and similar darlingtons are very hard to tweak, but Motorola 2N6284 tend to give good harmonic structure.

For opamps, in arbitrary circuit OPA2134 tend to give augmented 2nd order. It is easy tho to lower the 2nd order without introducing 3rd order in a carefully designed circuit.

OPA111 has even higher tendency than OPA2134 to augment the 2nd order in an arbitrary circuits.

In summary, each transistors have their own "sweet spot". Some wide, some narrow.
  Reply With Quote
Old 17th November 2012, 03:15 PM   #26
diyAudio Member
 
Join Date: Nov 2007
Location: Dallas
2nd harmonic is a frequency doubling.
If you DSP that in the time domain,
need not suffer 3rd or higher or IMD.

In immediate terms: A full wave
rectifier, followed by square law
distortion produces a pure 2nd.
But only if the input was a pure tone.
If a mix of tones, you get IMD also...

In physical terms, the Sitar effect:
String touching a Jawari each half cycle.

Last edited by kenpeter; 17th November 2012 at 03:21 PM.
  Reply With Quote
Old 19th November 2012, 08:32 AM   #27
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
This circuit will generate an adjustable proportion of almost pure H2 distortion.

The quantity is adjusted by means of R5:
Attached Images
File Type: png DistBox.png (229.7 KB, 158 views)
__________________
. .Circlophone your life !!!! . .
♫♪ My little cheap Circlophone© ♫♪
  Reply With Quote
Old 20th November 2012, 07:04 AM   #28
diyAudio Member
 
Join Date: Dec 2010
A analogic multiplier (e. g. a Gilbert cell like MC1496, CA3054) fed with the right signals (amplitude and phase) will also produce second harmonic. This technique was used in sythesisers.
  Reply With Quote
Old 20th November 2012, 07:10 AM   #29
Elvee is offline Elvee  Belgium
diyAudio Member
 
Elvee's Avatar
 
Join Date: Sep 2006
Quote:
Originally Posted by franzm View Post
A analogic multiplier (e. g. a Gilbert cell like MC1496, CA3054) fed with the right signals (amplitude and phase) will also produce second harmonic. This technique was used in sythesisers.
The circuit above is half a Gilbert cell, with deliberate and controlled leakage from one port
__________________
. .Circlophone your life !!!! . .
♫♪ My little cheap Circlophone© ♫♪
  Reply With Quote
Old 20th November 2012, 01:24 PM   #30
expert in tautology
diyAudio Member
 
bear's Avatar
 
Join Date: Apr 2002
Location: New York State USA
For modest 2nd, just build all single-ended?

_-_-bear
__________________
_-_-bear
http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- [...2SJ74 Toshiba bogus asian parts - beware! ]
  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
vented subwoofer build for live sound fandsen Subwoofers 4 19th August 2012 08:44 PM
Home build 6L6 pp amp no sound dscottguitars Instruments and Amps 1 12th August 2011 11:20 PM
What harmonic does to sound? lumanauw Solid State 154 20th September 2008 03:52 AM
any build this..how sound tadiam Solid State 4 30th August 2007 10:21 PM


New To Site? Need Help?

All times are GMT. The time now is 09:15 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