Simple 'treble cut' opamp circuit needed. - 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 18th July 2008, 10:47 PM   #1
diyAudio Member
 
Join Date: May 2008
Default Simple 'treble cut' opamp circuit needed.

Hi,

I've tried a search & also trawled the web....I can find lots of circuits with baxandall bass treble boost/cut circuits....all I seek is a simple treble cut circuit for a TL072 opamp. (or any opamp come to that!)

This is for a guitar with piezo pickups. Unprocessed these piezos sound a little harsh at the upper end, so I'd like to be able to roll this treble off a bit

I have magnetic pickups going through the same signal path (they are summed in TL072 opamp), which sound fine (no need for any treble cut), therefore I'd like the pot at one extremity *not* to affect the treble ...& at the other extremeity the treble to be rolled off (a bit like how a passive treble control rolls off the treble.

Many thanks in anticipation.
  Reply With Quote
Old 18th July 2008, 11:10 PM   #2
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Default Re: Simple 'treble cut' opamp circuit needed.

Quote:
Originally posted by HankMcSpank
Hi,

I've tried a search & also trawled the web....I can find lots of circuits with baxandall bass treble boost/cut circuits....all I seek is a simple treble cut circuit for a TL072 opamp. (or any opamp come to that!)

This is for a guitar with piezo pickups. Unprocessed these piezos sound a little harsh at the upper end, so I'd like to be able to roll this treble off a bit

I have magnetic pickups going through the same signal path (they are summed in TL072 opamp), which sound fine (no need for any treble cut), therefore I'd like the pot at one extremity *not* to affect the treble ...& at the other extremeity the treble to be rolled off (a bit like how a passive treble control rolls off the treble.

Many thanks in anticipation.
I would have just gone for a standard Baxendale design.
I play guitar a lot and prefer a more trebly sound.
The Baxendale will give you what you want but with the added option of treble boost.
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 19th July 2008, 01:45 AM   #3
diyAudio Member
 
Join Date: Dec 2006
Location: Where the sky loves the sea
1) see http://sound.westhost.com/projects-3.htm, indeed the entire site, all kinds of circuits, information, and ideas.

2) download a copy of LTspice and start messing about.
  Reply With Quote
Old 19th July 2008, 11:21 AM   #4
diyAudio Member
 
Join Date: May 2008
Nigel - The thing is about the baxandall it'd need an extra knob (bass), & I don't want to go putting another knob on my guitar!

Also, I don't want to emphasise the treble any more than it is at present (the piezos are *so* cutting already).

Like I say, all I need is a treble rolloff.


Mightydub - Re the linkl you gave. I'm aware of it - but I couldn't find anything that suits (I'm sure there is but I guess what I'm saying I'm not too sure how to hack one to suit my needs!)
  Reply With Quote
Old 19th July 2008, 11:22 AM   #5
Mooly is offline Mooly  United Kingdom
diyAudio Moderator
 
Mooly's Avatar
 
Join Date: Sep 2007
Do you even need an OpAmp. Simple = one pot ( 10k ) and one cap determined by experiment to suit you. Try values around 1000 pF to begin with.
Attached Images
File Type: jpg treble cut.jpg (10.5 KB, 203 views)
  Reply With Quote
Old 19th July 2008, 02:03 PM   #6
Eva is offline Eva  Spain
diyAudio Member
 
Eva's Avatar
 
Join Date: Oct 2003
Location: Near the sea
Send a message via MSN to Eva
Another potentiometer in series with the capacitor may be useful too. One determines shelf frequency and the other the amount of cut.
__________________
I use to feel like the small child in The Emperor's New Clothes tale
  Reply With Quote
Old 19th July 2008, 02:46 PM   #7
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
[QUOTE]Originally posted by HankMcSpank
[B]Nigel - The thing is about the baxandall it'd need an extra knob (bass), & I don't want to go putting another knob on my guitar!
QUOTE]

Why does it need a bass knob ?

Just remove the bass cct...........
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  Reply With Quote
Old 19th July 2008, 05:00 PM   #8
diyAudio Member
 
Join Date: Dec 2006
Location: Where the sky loves the sea
download Rod Elliot's crossover calculator:

http://sound.westhost.com/software/esp-lr13.exe

which has the abstract schematic and calculates values for 12dB or 24dB/octave Linkwitz-Riley filters. A very handy tool, makes it too easy really.

One disadvantage to doing this with an opamp is you need the +/- power supply, OK if the circuit goes in the amp but maybe a problem if it goes in the guitar. I suppose you could use 9V batteries.
  Reply With Quote
Old 19th July 2008, 05:41 PM   #9
diyAudio Member
 
Join Date: May 2008
Thanks guys.

in the end, (inspired by the simplicity of Mooly's suggestion), I continued searching & found this thread...

Tone circuit blues

Essentially that works for me!

I did try the baxandall, but I was getting faint ringing/static when turning the bass & treble controls (a bit like when tuning through an AM radio). Rather than try to get to the bottom of that (would anyone know what couldn have caused it?), I ripped all the associated extra components out - the simplicity of this solution suits me down to the groun.

many thanks once again.
  Reply With Quote
Old 19th July 2008, 05:46 PM   #10
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally posted by HankMcSpank
Thanks guys.

in the end, (inspired by the simplicity of Mool's suggestion), I continued searching & founf this thread...

Tone circuit blues

Essentially that works for me.

I did try the baxandall, but I was getting faint ringing/static (a bit like when tuning through an AM radio) when turning the bass & treble controls. Rather than try to get to the bottom of that (would anyone know what couldn have caused it?), I ripped all the associated extra components out - the simplicity of this solution suits me down to the groun.

many thanks once again.
But did you read the next message ?

"It forms a low-pass filter (treble cut) in conjunction with the output impedance of the opamp. As that impedance is going to be pretty low you should try adding a resistor in the wire between the opamp and the top of the tone pot."

I would be adding a resistor just before that filter.

I suspect you were getting high frequency noise with the baxandall cct. But if you were just using treble cut then that shouldnt have been a problem.
__________________
PCBCAD50 software. http://www.murtonpikesystems.co.uk
  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
TL071 opamp circuit needed space2000 Solid State 19 23rd May 2008 06:20 AM
Simple analog to s/pdif circuit needed for lab experiment. djsbriscoe Digital Source 3 13th November 2006 06:23 AM
Possible for a simple bass/treble cut in preamp?? mpmarino Solid State 0 24th December 2005 02:31 PM
simple phono preamp circuit needed needtubes Tubes / Valves 4 3rd July 2004 08:27 PM


New To Site? Need Help?

All times are GMT. The time now is 08:42 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