Preamp design schematics done - diyAudio
Go Back   Home > Forums > Live Sound > Instruments and Amps

Instruments and Amps Everything that makes music, Especially including instrument amps.

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 7th December 2008, 04:34 PM   #1
diyAudio Member
 
Join Date: Nov 2008
Default Preamp design schematics done

Ok here are the 2 schematics for the passive and active sections of an internal bass guitar preamp i've done. Comments and crits welcome people!



Click the image to open in full size.

Click the image to open in full size.
  Reply With Quote
Old 8th December 2008, 04:35 PM   #2
diyAudio Member
 
Join Date: Nov 2008
Ok , i''ve revised the schematics.

Athough, im still not very sure how to set up the first Op amp so that the input gain can be adjusted via a trim pot.

And also im not sure where the 2 outputs from the battery section go to.

can anyone shed some light on it for me?

thanks.

Click the image to open in full size.
  Reply With Quote
Old 13th December 2008, 12:01 AM   #3
Bill622 is offline Bill622  Canada
diyAudio Member
 
Join Date: Sep 2008
Hum... if there is a connection between R1 and R2 and C2, it looks like a +4.5V DC offset. Your opamp will have single supply of +9V instead of a dual supply, example: +9V and -9V. This means you need to rise the input signal with a DC offset of 4.5V (middle), which can be done with the first op-amp.

Read this documents, they talk about it and alot more (20 sec, search on Google )
http://instruct1.cit.cornell.edu/cou...ngleSupply.pdf

Good luck!
  Reply With Quote
Old 13th December 2008, 12:38 PM   #4
diyAudio Member
 
Join Date: Nov 2008
Thanks for the reply. Since i posted last i've manged to get the schematic completed. It took a while , but i got there!
  Reply With Quote
Old 13th December 2008, 02:52 PM   #5
Bill622 is offline Bill622  Canada
diyAudio Member
 
Join Date: Sep 2008
I would like to see your schematic, I plan to make myself a preamp too.

Thanks!
  Reply With Quote
Old 13th December 2008, 03:16 PM   #6
diyAudio Member
 
Join Date: Nov 2008
Here it is.

it uses 2 dual LM4562 op-amp chips. I'm not sure what the frequency cut offs for the bass, treble and mid are, as i took the EQ section from a mixer styled set up. This circuit will also run along side my passive electronics in the bass.

I'm currently using some PCB designing software to try and get the preamp made on as small a board as i can that will fit easily into the bass cavity with minumum routing.. using standard components it will fit onto a board about 125mm x 35mm. but i want to try and do it with surface mount components, as this will cut down the size even more.

If you have any input or ideas i'd like to hear them.

Click the image to open in full size.
  Reply With Quote
Old 1st January 2009, 05:53 PM   #7
Minion is offline Minion  Canada
diyAudio Member
 
Join Date: May 2006
Location: Cowican Bay , vancouver island
I like your design but I would re-think useing the LM4562 at the input as it is a Bipolar opamp and won"t like the 2m2 input impedance , I would use a Fet opamp at the input and use the Bipolar ones at the output...Pluss I believe useing those nice LM4562 in a Guitar preamp curcuit is a bit over kill as you will never be able to utilize the great specs in the LM4562 as the Noise intruduced by your patch cord will swamp all other curcuit noise.....

I also suggest that you put the Bias voltage on the input of every opamp not just IC1a.....The input bias voltage will also be on the output of the IC1a but it is Blocked by C6 so the next opamp doesn"t get a bias voltage which will cause the curcuit to be non functional...The Bias Voltage must be maintained on every opamps input (or on the Non-inverting input in an inverting configuration).....


Cheers
  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
Berman 76 preamp schematics arnoldc Tubes / Valves 12 17th February 2014 09:06 PM
6H30P preamp schematics Mrpong Tubes / Valves 18 6th November 2008 09:47 AM
New preamp schematics andrei Tubes / Valves 24 24th October 2008 01:20 AM
ecc preamp schematics please!!! kianbach Tubes / Valves 1 7th May 2005 01:31 AM
Old link to preamp schematics beppe61 Solid State 0 8th February 2005 12:51 PM


New To Site? Need Help?

All times are GMT. The time now is 03:17 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