Stomp Box Problems

jman 31 · 4th December 2008, 08:22 PM

I built this distortion project, and I can't seem to get it to work. All I get is silence (i can hear some noise when I turn the 10K pot and when I insert a jack, but no guitar sound). I swapped the two diodes for IN4007's because that's all I could find. I also swapped the op amp from the TL071 to a 741 from Radio Shack. Could these swaps cause this problem?

Here is the schematic I used.

Nigel Goodwin · 4th December 2008, 09:01 PM

Should work fine, although a little limited because the 741 is far lower spec - but it should work.

Measure the voltages round the chip - presumably you've connected the correct pins?, and the chip is the right way round?.

jman 31 · 4th December 2008, 09:26 PM

Yeah I got it to work (I had routed one of the wires wrong), but its not very loud at all. I guess maybe I'll order that chip. Would the diodes make any difference? Also, one of the 22K resistors is getting really hot is that normal?

Thanks for the input by the way.

Nigel Goodwin · 5th December 2008, 07:51 PM

No, the diodes won't make any difference - but there's no way a 22K resistor can get hot off a 9V battery - if it's getting hot, it's not a 22K. Even directly across the battery, it would only dissipate 0.004W.

jman 31 · 5th December 2008, 08:02 PM

OK I'll check the bands, it might have been in the wrong bin or something. Unless I grabbed a 22 instead of a 22K. Thanks again for the help. I will check on it.

jman 31 · 5th December 2008, 09:10 PM

Yep, that was it. wrong resistor. I will have to get the right ones and give it another try. Thanks

Minion · 5th December 2008, 10:57 PM

Actually I believe the Diodes do make a differance...I believe The diodes limit the output voltage to 0.7v......

I have noticed this with pretty much every Distortion unit I have built that uses Clipping Diodes on the output....

If you use LED"s you will get much more output (1.5v) and a more Nu-metal sound....if you get rid of the diodes all together it will be a lot louder but the overdrive might not be very pleasant.....

Cheers

jman 31 · 6th December 2008, 01:11 PM

I was wondering if I could use some 10 or 15K resistors in place of the 22K resistors. I believe it still halves the voltage, but I don't know the whole purpose of those resistors.

Any thoughts would be appreciated.

Jman

Minion · 6th December 2008, 03:41 PM

Thos resistors create a Voltage divider to give a Voltage referance at the input at half supply....You can use pretty much any 2 identical values accept too low a Value might cause your battery to drain quicker than usual....it should be fine with 15k....

Cheers

PS: you can also replace the 150k resistor in the feedback loop with a 100k-250k Potentiometer wired as a variable resistor which will let you dial in the ammount of gain you want, You can even put a switch on the Diodes so you can Enable/Disable diode clipping , or even put different diodes on a switch so you can get different Diode clipping tones , you can even use Mosfets as Diodes clippers but I like the sound of LED"s....

jman 31 · 6th December 2008, 05:38 PM

Thanks for the info. I will give it a try!

4th December 2008, 09:01 PM	#2
Nigel Goodwin diyAudio Member Join Date: Jul 2005 Location: North Derbyshire	Should work fine, although a little limited because the 741 is far lower spec - but it should work. Measure the voltages round the chip - presumably you've connected the correct pins?, and the chip is the right way round?. __________________ Nigel Goodwin

5th December 2008, 07:51 PM	#4
Nigel Goodwin diyAudio Member Join Date: Jul 2005 Location: North Derbyshire	No, the diodes won't make any difference - but there's no way a 22K resistor can get hot off a 9V battery - if it's getting hot, it's not a 22K. Even directly across the battery, it would only dissipate 0.004W. __________________ Nigel Goodwin

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
DG Stomp	cajwit	Instruments and Amps	1	21st May 2011 11:33 AM
Yamaha DG-Stomp schematics????	darkiller86	Instruments and Amps	9	24th June 2008 07:24 PM
yamaha dg stomp	varde	Instruments and Amps	2	19th June 2008 01:31 PM
DG Stomp	cajwit	Instruments and Amps	1	18th December 2007 06:54 AM
Need Advice On Converting a Stomp Box Preamp	turbolx5oh	Instruments and Amps	3	14th July 2006 08:09 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

4th December 2008, 09:26 PM	#3
jman 31 diyAudio Member Join Date: Oct 2008 Location: Florida	Yeah I got it to work (I had routed one of the wires wrong), but its not very loud at all. I guess maybe I'll order that chip. Would the diodes make any difference? Also, one of the 22K resistors is getting really hot is that normal? Thanks for the input by the way.

5th December 2008, 08:02 PM	#5
jman 31 diyAudio Member Join Date: Oct 2008 Location: Florida	OK I'll check the bands, it might have been in the wrong bin or something. Unless I grabbed a 22 instead of a 22K. Thanks again for the help. I will check on it.

5th December 2008, 09:10 PM	#6
jman 31 diyAudio Member Join Date: Oct 2008 Location: Florida	Yep, that was it. wrong resistor. I will have to get the right ones and give it another try. Thanks

5th December 2008, 10:57 PM	#7
Minion diyAudio Member Join Date: May 2006	Actually I believe the Diodes do make a differance...I believe The diodes limit the output voltage to 0.7v...... I have noticed this with pretty much every Distortion unit I have built that uses Clipping Diodes on the output.... If you use LED"s you will get much more output (1.5v) and a more Nu-metal sound....if you get rid of the diodes all together it will be a lot louder but the overdrive might not be very pleasant..... Cheers

6th December 2008, 01:11 PM	#8
jman 31 diyAudio Member Join Date: Oct 2008 Location: Florida	I was wondering if I could use some 10 or 15K resistors in place of the 22K resistors. I believe it still halves the voltage, but I don't know the whole purpose of those resistors. Any thoughts would be appreciated. Jman

6th December 2008, 03:41 PM	#9
Minion diyAudio Member Join Date: May 2006	Thos resistors create a Voltage divider to give a Voltage referance at the input at half supply....You can use pretty much any 2 identical values accept too low a Value might cause your battery to drain quicker than usual....it should be fine with 15k.... Cheers PS: you can also replace the 150k resistor in the feedback loop with a 100k-250k Potentiometer wired as a variable resistor which will let you dial in the ammount of gain you want, You can even put a switch on the Diodes so you can Enable/Disable diode clipping , or even put different diodes on a switch so you can get different Diode clipping tones , you can even use Mosfets as Diodes clippers but I like the sound of LED"s....

6th December 2008, 05:38 PM	#10
jman 31 diyAudio Member Join Date: Oct 2008 Location: Florida	Thanks for the info. I will give it a try!

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)