A DIY adaption of a Mesa Boogie 5 band eq found in many Mesa Boogie amps. Original tonestack has inductors but is is changed to op amp gyrators. This design was created by Cameron (thanks!) and layouts is verified by AlexS(thanks again, mate!)
It started with Cameron researching the true values AND curves of the original inductor design, not just going by the label like many do. Then he made the calculations so Anders could adapt it to an efficient op amp layout.
While the original uses, and works well with 50k pots, I'm having luck with W20Ks for more even travel. It sounds excellent in my Mesa effects loop. It's flat and unity gain with controls at noon. Dipping that middle slider is the sound I've been after for years.
Hello, I built the two EQ layouts of Sabrotone based on op-amp gyrators (the 5-bands and the 3-band with variable Q and freq). Both are too noisy! A constant background hiss like a metal distortion usually do. Both work very well, sounds nice but in the clean channel it's better play without these EQ because the noise, and in the gain channel it's impossibile to use. Someone said those are quite, but I bet they aren't really quite. I'm sure I didn't make the same mistake on two different boards. I'm searching a parametric eq on veroboard that works fine without this hiss, I'm wondering if this Mesa Boogie based work better or the op amp gyrators are impossibile to use in guitar devices.
Hi, I am the designer of this mesa-inspired circuit. The only things that I can see with the Sabrotone circuits that would be causing your horrible hiss would be either poor decoupling in the power supply, noisy op-amps, or noisy resistors. Op-amp gyrators work just fine in guitar circuits, but it's important to use quiet op-amps or else the hiss will be terrible at high boost settings. Replacing the 150pf C12 in the 3-band eq with something around 560 pf would probably help the hiss a little, but try running the pedals with batteries to see if the hiss disappears (or at least decreases). If it does, the power supply is the problem. If not, try replacing the TL07x op-amps with OPA4134's and OPA134's, which are more than twice as quiet as the TL07x op-amps. If these things don't solve the hiss, I don't know what could be wrong, but it's not the op-amp gyrators.
Thanks for your reply. The weird things is this happend with two different versions. In the 3-band the less hiss I get is in flat, the noise, (a FFFFF noise) raise up when I boost or when I cut. Anyway, I use metal film resistors, and the ICs are a TL072 and a TL074. I guess I didn't try it with battery, but I think it's not that kind of noise. I'll try it, anyway.
These looks doable. Echoplex Preamp could be done with trimpots for the J FETS?. Also the schematic calls for separate grounds for the audio path and the power section. I'm not sure how to wire it up.
It might take a few days until I can draw these since we live in quite crazy times now and I'm not one of those who is in quarantine and happen to work more than ever....
I built the eq works perfect awesome eq. I don’t even have it boxed up yet and it don’t have any noise hiss nothing super quiet. Yes dipping that middle slider down gets you in older Metallica territory.
I built the eq works perfect awesome eq. I don’t even have it boxed up yet and it don’t have any noise hiss nothing super quiet. Yes dipping that middle slider down gets you in older Metallica territory.
I built the eq works perfect awesome eq. I don’t even have it boxed up yet and it don’t have any noise hiss nothing super quiet. Yes dipping that middle slider down gets you in older Metallica territory.
Im just finished ,, but I have some problems .. the signal of guitar distorted with weird sound .. I turn the volume to 10-20% and the signal goes to clean , but when I turn my amp on overdrive channel . The signal gone and I hear some buzzzzzzzzzzzzzzz… I don’t know what happen .. if someone knows about distorted signal.. thank you
Yes I’m using the icl7660 without S … it's not just the buzz in the sound.. it is also the distortion that takes place and in short it does not work properly. the signal does not pass through the circuit properly.. so you say if I change the I.c. To S .. the circuit work ?!?!?..
Not sure if your build will work as intended by only sub the charge pump since might have other issues in your build. The easiest way to locate errors would be by an audio probe and/or meassure the voltages at each pin of all three ICs.
This circuit runs on bipolar power so pin 4 for both IC1 and IC2 should read 9v and pin 11 of both IC1 and IC2 should read -9v. All other pins of IC1 and IC2 should read 0v. For the charge pump, pin 1 and 8 should read 9v, pin 3 0v and pin 5 -9v. That is at least a start to locate where the error could be.
Maybe I have problem … but I check the board and it’s clean without shortcuts or wrong jumpers and cuts … it’s like your phone layout … I am trying tomorrow with audio probe if find something
Update !!! .. I disconnect the bands cables from breadboard and the input-output- everything ! . I connect only the VDC and the ground to my 9 vdc adapter ( it’s a diy box with 8 gates of clean 9vdc. Anyway :p ) .. so now the voltage is 9vdc and after the diode ( I put 1N5818 instead the 1N5817 ) are 8.38vdc .. on the ic1 and ic2 the 4 pin the voltage are 8.40vdc ..on the 11 pin are -7 vdc and all other pins have a little voltage like 0.5 and 0.15 vdc max .. and on pumps 1 and 8 pin are 8.38 . On the 5 pin are -6.75 vdc and pin 3 are 0.52 vdc.. that the right metrics now .. the numbers are correct ?
The voltages looks alright for the most part. The negative voltage is too low though, it has to mirror the positive voltage, otherwise the op amps will not be biased correctly. There is something that eats your negative voltage, maybe a tiny solder bridge somewhere.
When sourcing the correct charge pump, avoid ebay and Tayda since there is low quality / fakes floating around. You are in Europe, right? Musikding, Banazi and other DIY pedal retalers is the ones to shop from.
Fuzzhead YOU ARE AWESOME !!!!.. i turn on the bright lights , I put the magnifier. And I start to search for the problem ,,, and I found that s@it!!!!!!!.. as you say there is a tiny tiny solder bridge on rail D and connect with E close to electrolytic cap … I remove that ,, check for voltage ,, and I put without the bands cables ( only I connect the -all bands 1 and all bands 3 with 47k resistor ) to my breadboard ,,, sounds now is clear without distortion and buzz and noise , and pass through nice ,,, I’m trying now to add the bands …… thank you master fuzzhead !!
I make complete test with my breadboard … I have noise but it’s ok because from icl7660( must change with S type).. sound is amazing and all of the bands are work perfect 👍…. Thank you AGAIN fuzzhead …
Just I add the icl760s on board …. The buzz sound and the noise gone !! Work great …. Just careful only the icl7660s or max1044 work without noise … thanx a lot fuzzhead again
Thank you so much for this EQ. I checked the curves against Amplitube Mark series and Helix Cali EQ and this EQ does pretty much the same thing. The Q seems to vary a bit with this effect, not sure how the original performs. The Q gets narrower with higher boost/cut levels. Also this effect seems to have a bit more cut/boost range. Which is great. If you use ears, you nail the sound regardless. I added this EQ to the FX loop of my 5150 while disabling stock 5150 EQ by cutting mid pot to ground connection via a switch. This gave me an instant Mesa Boogie tone, and im beyond amazed how it sounds. I have also a Fender tonestack pedal which i use to push the front end, which gets me super close to Mark series tone. This project is priceless.
Many thanks for sharing! This is an excellent EQ. Built with zero issues. using TC1044SCPA or LT1054, works well. 50KB slider pots seem to operate just fine. No noise. Sounds even better running on 12V supply. https://youtube.com/shorts/q2fa_kSialk
update: replaced the TL074 with OPA4134 opamps. result: noticeable improvement (both running at 12V) highly recommend using OPA4134 if you can get hold of them.
here’s another demo: https://youtube.com/shorts/t2a2TLPt6CE
i finished and tested but in the fx loop of my 5153 there is a pretty big volume drop.eq works great other than that. any suggestions on how to bump up the volume on this?
Thanks a lot for this, I've built it for someone, also used OPA4134. I posted a crude video sample as well on this link, using a modded Crate BV120 and a 2xV30 cab intentionally for that mid spike to show the EQ functionality of getting the nice “Mesa V shape scooped” thing: https://hgecontraptions.blogspot.com/2024/03/mesa-boogie-5-band-eq-for-fx-loops.html
Holy crap this looks awesome.
ReplyDeleteIt started with Cameron researching the true values AND curves of the original inductor design, not just going by the label like many do. Then he made the calculations so Anders could adapt it to an efficient op amp layout.
ReplyDeleteWhile the original uses, and works well with 50k pots, I'm having luck with W20Ks for more even travel. It sounds excellent in my Mesa effects loop. It's flat and unity gain with controls at noon. Dipping that middle slider is the sound I've been after for years.
Thanks, Cameron and Anders!
Nice man, petrucci scoop? Im realt looking forward to seeing what this works well with.
ReplyDeleteHello, I built the two EQ layouts of Sabrotone based on op-amp gyrators (the 5-bands and the 3-band with variable Q and freq).
ReplyDeleteBoth are too noisy! A constant background hiss like a metal distortion usually do. Both work very well, sounds nice but in the clean channel it's better play without these EQ because the noise, and in the gain channel it's impossibile to use.
Someone said those are quite, but I bet they aren't really quite. I'm sure I didn't make the same mistake on two different boards.
I'm searching a parametric eq on veroboard that works fine without this hiss, I'm wondering if this Mesa Boogie based work better or the op amp gyrators are impossibile to use in guitar devices.
Hi, I am the designer of this mesa-inspired circuit. The only things that I can see with the Sabrotone circuits that would be causing your horrible hiss would be either poor decoupling in the power supply, noisy op-amps, or noisy resistors. Op-amp gyrators work just fine in guitar circuits, but it's important to use quiet op-amps or else the hiss will be terrible at high boost settings. Replacing the 150pf C12 in the 3-band eq with something around 560 pf would probably help the hiss a little, but try running the pedals with batteries to see if the hiss disappears (or at least decreases). If it does, the power supply is the problem. If not, try replacing the TL07x op-amps with OPA4134's and OPA134's, which are more than twice as quiet as the TL07x op-amps. If these things don't solve the hiss, I don't know what could be wrong, but it's not the op-amp gyrators.
DeleteThanks for your reply. The weird things is this happend with two different versions.
DeleteIn the 3-band the less hiss I get is in flat, the noise, (a FFFFF noise) raise up when I boost or when I cut.
Anyway, I use metal film resistors, and the ICs are a TL072 and a TL074. I guess I didn't try it with battery, but I think it's not that kind of noise. I'll try it, anyway.
Hey man, didnt have any noise or hiss issue, but my 7660s got hot and the lower tl074 after a while. But defo works.
ReplyDeleteI do have a coupla requests.
The mids and lower mids im not a fan of, would it just be the caps to play with to change freq or whats the scheme there?
Also- any chance of the xotic ep booster, and echoplex preamp from aion?
These looks doable. Echoplex Preamp could be done with trimpots for the J FETS?. Also the schematic calls for separate grounds for the audio path and the power section. I'm not sure how to wire it up.
DeleteIt might take a few days until I can draw these since we live in quite crazy times now and I'm not one of those who is in quarantine and happen to work more than ever....
I built the eq works perfect awesome eq. I don’t even have it boxed up yet and it don’t have any noise hiss nothing super quiet. Yes dipping that middle slider down gets you in older Metallica territory.
ReplyDeleteI built the eq works perfect awesome eq. I don’t even have it boxed up yet and it don’t have any noise hiss nothing super quiet. Yes dipping that middle slider down gets you in older Metallica territory.
ReplyDeleteI built the eq works perfect awesome eq. I don’t even have it boxed up yet and it don’t have any noise hiss nothing super quiet. Yes dipping that middle slider down gets you in older Metallica territory.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteThis comment has been removed by the author.
ReplyDeleteIm just finished ,, but I have some problems .. the signal of guitar distorted with weird sound .. I turn the volume to 10-20% and the signal goes to clean , but when I turn my amp on overdrive channel . The signal gone and I hear some buzzzzzzzzzzzzzzz… I don’t know what happen .. if someone knows about distorted signal.. thank you
ReplyDeleteI forgot to a say I’m using icl7660 instead of 7660s. It’s different ?
DeleteIf you use ICL7660 without the "S" suffix you will end up with lots of noise. ICL7660S or MAX1044 is the ones to use.
DeleteYes I’m using the icl7660 without S … it's not just the buzz in the sound.. it is also the distortion that takes place and in short it does not work properly. the signal does not pass through the circuit properly.. so you say if I change the I.c. To S .. the circuit work ?!?!?..
DeleteNot sure if your build will work as intended by only sub the charge pump since might have other issues in your build. The easiest way to locate errors would be by an audio probe and/or meassure the voltages at each pin of all three ICs.
DeleteThis circuit runs on bipolar power so pin 4 for both IC1 and IC2 should read 9v and pin 11 of both IC1 and IC2 should read -9v. All other pins of IC1 and IC2 should read 0v.
For the charge pump, pin 1 and 8 should read 9v, pin 3 0v and pin 5 -9v.
That is at least a start to locate where the error could be.
Here my metrics with the batt”s voltage are 8.86 v
DeleteIc1 pins
1) .22v 2).14v 3) .017v 4) 7.90 5) .17v 6) .025v 7) .30v
8) .17v 9) .22v 10) .32v 11) -6.55 12) .30v 13) .25v 14) .34v
IC2 pins
1) .66v 2).56v 3) .28v 4) 8.06v 5) .40v 6) .41v 7) .52v
8) .54v 9) .36v 10) .40v 11) -6.84v 12) .57v 13) .51v 14) .61v
And the icl7660
Pins 1 and 8 are 8.05 v
And the pin 8 are -5.98v
Maybe I have problem … but I check the board and it’s clean without shortcuts or wrong jumpers and cuts … it’s like your phone layout … I am trying tomorrow with audio probe if find something
Update !!! .. I disconnect the bands cables from breadboard and the input-output- everything ! . I connect only the VDC and the ground to my 9 vdc adapter ( it’s a diy box with 8 gates of clean 9vdc. Anyway :p ) .. so now the voltage is 9vdc and after the diode ( I put 1N5818 instead the 1N5817 ) are 8.38vdc .. on the ic1 and ic2 the 4 pin the voltage are 8.40vdc ..on the 11 pin are -7 vdc and all other pins have a little voltage like 0.5 and 0.15 vdc max .. and on pumps 1 and 8 pin are 8.38 . On the 5 pin are -6.75 vdc and pin 3 are 0.52 vdc.. that the right metrics now .. the numbers are correct ?
ReplyDeleteThe voltages looks alright for the most part. The negative voltage is too low though, it has to mirror the positive voltage, otherwise the op amps will not be biased correctly. There is something that eats your negative voltage, maybe a tiny solder bridge somewhere.
DeleteWhen sourcing the correct charge pump, avoid ebay and Tayda since there is low quality / fakes floating around. You are in Europe, right? Musikding, Banazi and other DIY pedal retalers is the ones to shop from.
Fuzzhead YOU ARE AWESOME !!!!.. i turn on the bright lights , I put the magnifier. And I start to search for the problem ,,, and I found that s@it!!!!!!!.. as you say there is a tiny tiny solder bridge on rail D and connect with E close to electrolytic cap … I remove that ,, check for voltage ,, and I put without the bands cables ( only I connect the -all bands 1 and all bands 3 with 47k resistor ) to my breadboard ,,, sounds now is clear without distortion and buzz and noise , and pass through nice ,,, I’m trying now to add the bands …… thank you master fuzzhead !!
DeleteI make complete test with my breadboard … I have noise but it’s ok because from icl7660( must change with S type).. sound is amazing and all of the bands are work perfect 👍…. Thank you AGAIN fuzzhead …
ReplyDeleteGreat! Let us know how it works when you got the correct charge pump.
DeleteOf course .. I order icl7660s . Maybe next week have it …
DeleteJust I add the icl760s on board …. The buzz sound and the noise gone !! Work great …. Just careful only the icl7660s or max1044 work without noise … thanx a lot fuzzhead again
ReplyDeleteThank you so much for this EQ. I checked the curves against Amplitube Mark series and Helix Cali EQ and this EQ does pretty much the same thing. The Q seems to vary a bit with this effect, not sure how the original performs. The Q gets narrower with higher boost/cut levels. Also this effect seems to have a bit more cut/boost range. Which is great. If you use ears, you nail the sound regardless. I added this EQ to the FX loop of my 5150 while disabling stock 5150 EQ by cutting mid pot to ground connection via a switch. This gave me an instant Mesa Boogie tone, and im beyond amazed how it sounds. I have also a Fender tonestack pedal which i use to push the front end, which gets me super close to Mark series tone. This project is priceless.
ReplyDeleteHi,is there a place where i can find the schematic? Thx
ReplyDeleteMany thanks for sharing! This is an excellent EQ.
ReplyDeleteBuilt with zero issues. using TC1044SCPA or LT1054, works well.
50KB slider pots seem to operate just fine.
No noise. Sounds even better running on 12V supply.
https://youtube.com/shorts/q2fa_kSialk
update: replaced the TL074 with OPA4134 opamps.
ReplyDeleteresult: noticeable improvement (both running at 12V)
highly recommend using OPA4134 if you can get hold of them.
here’s another demo:
https://youtube.com/shorts/t2a2TLPt6CE
i finished and tested but in the fx loop of my 5153 there is a pretty big volume drop.eq works great other than that. any suggestions on how to bump up the volume on this?
ReplyDeletebuilt with the listed parts.
ReplyDeletewhat do you mean all band? is that the same with hz pot? tia
ReplyDeleteHELLO EVERYTHING IS FINE? Where can I find the schematic? grateful
ReplyDeleteThanks a lot for this, I've built it for someone, also used OPA4134. I posted a crude video sample as well on this link, using a modded Crate BV120 and a 2xV30 cab intentionally for that mid spike to show the EQ functionality of getting the nice “Mesa V shape scooped” thing: https://hgecontraptions.blogspot.com/2024/03/mesa-boogie-5-band-eq-for-fx-loops.html
ReplyDelete