Yes, the HPF is part of the design. I believe somewhere in this thread I made a suggestion for a cap change to reduce the filter.
EDIT: Found it.
DIY Stingray 3EQ Preamp
Last edited:
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DIY Stingray 3EQ Preamp
- Thread starter Dominic D
- Start date
EDIT: Found it.
DIY Stingray 3EQ Preamp
Hello guys,
I came back just to post the new curve of my preamp, I switched the 8.2nF caps for 100nF, HPF is gone.
I came back just to post the new curve of my preamp, I switched the 8.2nF caps for 100nF, HPF is gone.
I Know I am late to the party but was looking for help the Mouser cart on some of the resistors has a 200 min order cant seem to find substitutes that have all the same values can you use ones with a 1/4 power rating or a higher percent tolerance??
Hi Dominic D , thanks for your time creating this project. I'll try to build in the near future 
One question, that has been asked in the thread but I didn't see the answer: how would you add the on/off switch to the amp so you can disconnect it and use it in passive mode? But maintaining the EQ settings, not just bypassing the whole preamp.
Thanks and regards
One question, that has been asked in the thread but I didn't see the answer: how would you add the on/off switch to the amp so you can disconnect it and use it in passive mode? But maintaining the EQ settings, not just bypassing the whole preamp.
Thanks and regards
Hello Picoto,
I'm not a huge specialist like Dominic, but let me give me some info, in case of Dom don't answer so quickly.
Add a switch to alternate between passive and active is possible, but keep the EQ in passive mode it is not, because you need the circuit working to have the EQ working. What is possible is to add a switch and probably keep one of the knobs as a "tone" knob, like any passive circuit.
I'm not a huge specialist like Dominic, but let me give me some info, in case of Dom don't answer so quickly.
Add a switch to alternate between passive and active is possible, but keep the EQ in passive mode it is not, because you need the circuit working to have the EQ working. What is possible is to add a switch and probably keep one of the knobs as a "tone" knob, like any passive circuit.
Thanks Gabriel_cwb !
I'll scratch my head, maybe I come up with something. I'm thinking of using a POT with switch action to control ON/OFF status
I'll scratch my head, maybe I come up with something. I'm thinking of using a POT with switch action to control ON/OFF status
I'm simulating the circuit in PSpice and I have some doubts:
- Why don't include a LPF at the output? to remove frequencies above 4KHz (e.g.). Just adding a couple of C.
- Currently the tone control seems way off for the treble:
(all pots middle point but the one under test, 0 to 50Kohms)
Also, it would make more sense to me to adjust the gain around 40Hz for the bass tune and 300 Hz for the mid, being the treble centered around 1KHz
What would you think of my mods? (including the C4, C6 adjustment). This is how it would look like:
All pots middle point:
TREBLE tune:
I can provide more details and comparisons wrt to the original (and great!) design
Regards,
- Why don't include a LPF at the output? to remove frequencies above 4KHz (e.g.). Just adding a couple of C.
- Currently the tone control seems way off for the treble:
(all pots middle point but the one under test, 0 to 50Kohms)
Also, it would make more sense to me to adjust the gain around 40Hz for the bass tune and 300 Hz for the mid, being the treble centered around 1KHz
What would you think of my mods? (including the C4, C6 adjustment). This is how it would look like:
All pots middle point:
TREBLE tune:
I can provide more details and comparisons wrt to the original (and great!) design
Regards,
Hello there folks, long time lurker here. First time poster...
English is not my first language so take this in consideration if something seems a little odd
I've built this preamp as a stomp box twice now and I keep getting distortion in the output as soon as I dig a little deeper on my playing. It's a fuzzy quiet sound in the upper side of the audio spectrum that won't go away even when I dim the input. I've already built the stingray 2 band eq and the g&l preamps as stomp boxes and none of them presented any issues whatsoever. This second circuit is already built on a perfboard but the connections are made yet via a test board so the stomp box connections are out of the equation. I've been using the TL072 and TL082 as ICs but have no meaning to verify if they're authentic so maybe this can be an issue.
In the first attempt building this circuit I used typical voltage/wattage (16v/25v/0.25w) components. I wondered if that was the problem so in the second attempt I used over sized components (with the exception of the electrolytic capacitors) to no avail. In the first circuit I used 22nF capacitors on the HPF portion to accommodate the low B string low frequencies and wondered afterwards if the excessive bass was over-driving the circuit. Changed that for the original 8,2nF and the issue did not disappeared.
I have little knowledge on electronics and I mostly do this as an attempt to acquire knowledge while also being cheap. I have limited access to analysis equipment so I mostly do things "by ear".
I've described all this here to see if anyone had the same experience and if yes what was the solution.
Any help would be very welcomed.
Thanks in advance
English is not my first language so take this in consideration if something seems a little odd
I've built this preamp as a stomp box twice now and I keep getting distortion in the output as soon as I dig a little deeper on my playing. It's a fuzzy quiet sound in the upper side of the audio spectrum that won't go away even when I dim the input. I've already built the stingray 2 band eq and the g&l preamps as stomp boxes and none of them presented any issues whatsoever. This second circuit is already built on a perfboard but the connections are made yet via a test board so the stomp box connections are out of the equation. I've been using the TL072 and TL082 as ICs but have no meaning to verify if they're authentic so maybe this can be an issue.
In the first attempt building this circuit I used typical voltage/wattage (16v/25v/0.25w) components. I wondered if that was the problem so in the second attempt I used over sized components (with the exception of the electrolytic capacitors) to no avail. In the first circuit I used 22nF capacitors on the HPF portion to accommodate the low B string low frequencies and wondered afterwards if the excessive bass was over-driving the circuit. Changed that for the original 8,2nF and the issue did not disappeared.
I have little knowledge on electronics and I mostly do this as an attempt to acquire knowledge while also being cheap. I have limited access to analysis equipment so I mostly do things "by ear".
I've described all this here to see if anyone had the same experience and if yes what was the solution.
Any help would be very welcomed.
Thanks in advance
If the musicman pickup is parallel, where would the other hot connection go for the other coil?
Sorry for not replying sooner but I've been out of circulation for a while due to a stay in hospital.
Parallel connection is where both hot connections are connected together so the other hot connection should be connected to the input (and the ground connection to ground) otherwise you would have single coil.
No need to apologize, I took longer than you to respond. When you say that, do you mean both Parallel connections go to the same spot marked as input in the diagram?
Yes, both pickup hot connections to the preamp input, both cold connections to the preamp ground.
Link to a random website with a diagram (which probably makes more sense than my ramblings). It shows a 6 string humbucker but the same applies to bass humbuckers. The first diagram shows parallel and series humbucker connections.
https://www.danieleturani.com/wirin...h-autosplit-serial-parallel-switch-push-pull/
Link to a random website with a diagram (which probably makes more sense than my ramblings). It shows a 6 string humbucker but the same applies to bass humbuckers. The first diagram shows parallel and series humbucker connections.
https://www.danieleturani.com/wirin...h-autosplit-serial-parallel-switch-push-pull/
Good evening! Planning to mod a Harley Benton MB-4 using an original musicman 5-string ceramic pickup I have in store to create a "Poor Man's Old Smoothie". I was looking for a preamp and found this thread. Would this work with such a pickup? I also plan to add 2 SPDT switches for parallel/series option.
I have not red all the posts here, but I see few breadboard builds. I accidentally came across a pcb in ebay for $11. I have actually bought it and soldered together. I like it, I think it is good preamp It appears to be based on the same schematic as being discussed here. So I figured I post the link to it in case someone having a difficulty hand wiring or etching it's own. Perhaps this was already posted here, do not kill me over it.
3EQ Bass Preamp - DIY PCB guitar | eBay
I use this in modified Peavey Grind with VFL pickups (like in Peavey Cirrus).
For whatever it worth, here is my "report".,
I soldered it myself using all components as per schematic, but I have substituted TL062 preamp with TL072 as I already had those from my previous projects. Seems to be working fine. Also I replaced volume pot with a jumper and 25k resistor to simulate full volume. I use dual volume between pickups and the preamp input as I personally prefer dual volume, This volume method also changes tone a bit like in passive wiring, which I like. For tone pots I am currently use linear 250k pots without detent as that is what I had laying around and they seems to work great. In A/B compare between this preamp and standard passive tone wiring, I can not hear much difference. In the middle point for 3-band it sounds pretty much identical to passive with tone pot not used. Seems to be taking the hi all the way down, and maybe just taking mids down 50% replicates passive tone all the way down. This preamp EQ seems to be very functional as expected. Also I run it at 18V as my active pickups are 18V. Prior to that I did compare powering the preamp with 9V and 18V and since I could not hear any difference I just powered the whole thing by 18v to make more straight forward than tapping one battery for the preamp.
Not sure if this causes for batteries to last longer or shorter... I use li-ion rechargeable from Amazon (EBL brand). I did not wait to run the batteries dry and see how long it takes. I just randomly replace batteries every couple of weeks. I play on average at least 1 hour a day most likely more. Talking about li-ion batteries, I tried two kinds with the built in charger (battery has USB jack) and those not good, lots of hissing noise. The batteries that need a desktop charger seems to work great and I did not hear any difference comparing to Energizer and Amazon Basics. I have 4 of these EBL batteries, have two in the charger and two in the bass. There is a weakness in this preamp design, it does not have reverse polarity protection. Reversing polarity on the power fries the op-amp. I would recommend to solder a socket for the preamp as that will facilitate quick replacement. I put that in so later I might change to TL062, but reading about it, it seems like TL072 is basically identical for the purposes of this design. I did try to plug a pile of different op-ams I have laying around such as JRC4558, 4560, MUSES 8820, LM4562... All do work in the board, but many distort at hard plucking (powered by 9v and 18v the same). The ones that work best were TL072 and JRC4560 and did not distort. I personally think TL072 is better chip than JRC4560 so I stuck with that.
This ended up a bit long winded, sorry about this
3EQ Bass Preamp - DIY PCB guitar | eBay
I use this in modified Peavey Grind with VFL pickups (like in Peavey Cirrus).
For whatever it worth, here is my "report".,
I soldered it myself using all components as per schematic, but I have substituted TL062 preamp with TL072 as I already had those from my previous projects. Seems to be working fine. Also I replaced volume pot with a jumper and 25k resistor to simulate full volume. I use dual volume between pickups and the preamp input as I personally prefer dual volume, This volume method also changes tone a bit like in passive wiring, which I like. For tone pots I am currently use linear 250k pots without detent as that is what I had laying around and they seems to work great. In A/B compare between this preamp and standard passive tone wiring, I can not hear much difference. In the middle point for 3-band it sounds pretty much identical to passive with tone pot not used. Seems to be taking the hi all the way down, and maybe just taking mids down 50% replicates passive tone all the way down. This preamp EQ seems to be very functional as expected. Also I run it at 18V as my active pickups are 18V. Prior to that I did compare powering the preamp with 9V and 18V and since I could not hear any difference I just powered the whole thing by 18v to make more straight forward than tapping one battery for the preamp.
Not sure if this causes for batteries to last longer or shorter... I use li-ion rechargeable from Amazon (EBL brand). I did not wait to run the batteries dry and see how long it takes. I just randomly replace batteries every couple of weeks. I play on average at least 1 hour a day most likely more. Talking about li-ion batteries, I tried two kinds with the built in charger (battery has USB jack) and those not good, lots of hissing noise. The batteries that need a desktop charger seems to work great and I did not hear any difference comparing to Energizer and Amazon Basics. I have 4 of these EBL batteries, have two in the charger and two in the bass. There is a weakness in this preamp design, it does not have reverse polarity protection. Reversing polarity on the power fries the op-amp. I would recommend to solder a socket for the preamp as that will facilitate quick replacement. I put that in so later I might change to TL062, but reading about it, it seems like TL072 is basically identical for the purposes of this design. I did try to plug a pile of different op-ams I have laying around such as JRC4558, 4560, MUSES 8820, LM4562... All do work in the board, but many distort at hard plucking (powered by 9v and 18v the same). The ones that work best were TL072 and JRC4560 and did not distort. I personally think TL072 is better chip than JRC4560 so I stuck with that.
This ended up a bit long winded, sorry about this
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I wanted to follow up on this. First, I have rewired the bass so it runs on 9V and uses the two 9V batteries in parallel to extend the life. With 9V the bass draws nearly half the current and since 18V does not contribute to any improvements, might as well extend the battery life. I also put the 50K pots for tone control instead of 250K pots. This actually changed things. I think 250K pots give more boost range, but I am not sure if that is actually a good thing as it also boosts the noise. For now I will leave 50K pts as I am happy with the range they give. I also have found TL062 and tried it in. I think there is no tone difference at all, but with TL062, the bass consumes less power. I have an ok multimeter, not RMS, but it is not the one that HB gives away with a purchase. So, the numbers I have measured are basically:
TL072 on 18V = 136mW
TL072 on 9v = 63mW
TL062 on 9V = 35mW
The above also includes the active VFL pickups although between both of them I think they consume less than 2mW.
The sound/tone is exactly the same regardless if it is TL072 or TL062. Whether it is powered with 18V or 9V make no difference either. The winner is as expected TL062 since it offers the same tone and maximizes the battery life. With the 600mAh rechargeables I use, I should get about 300 hours of continuous ON time.
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Unfortunately, I don’t have the files anymore. I haven’t touched this project in years.
