Haven't been around much due to surgery and other health problems.
Glad to see the schematics were useful.
Hum and noise problems can usually be eliminated by single point (star) grounding and keeping the wires to the tone control pots as short as possible, or even shielding them. Sticky back copper foil can be used to shield the wiring cavity if necessary. It can be found at most hobby stores. I remember seeing shielding kits for guitars someplace, but I don’t remember where. Maybe someone here knows.
Glad to see the schematics were useful.
Hum and noise problems can usually be eliminated by single point (star) grounding and keeping the wires to the tone control pots as short as possible, or even shielding them. Sticky back copper foil can be used to shield the wiring cavity if necessary. It can be found at most hobby stores. I remember seeing shielding kits for guitars someplace, but I don’t remember where. Maybe someone here knows.
www.stewmac.com provides several types of shielding material from adhesive copper tape to conductive paint
I use baking foil and cheap glue for shielding on all my guitars, and it works fine (though it can be fiddly to get in to odd shaped spaces).
You can also buy shielding kits from any decent luthier supplier (am I allowed to mention names on this forum? Not sure, but typing "Luthier Supplies" into Google will probably work as well as anything....)
But then again, if we were the type to just go out and buy stuff, we probably would not be on this forum. Both the above sites will furnish you with an manner of pre-amps, but where is the fun in that?
Incidentally, the three band EQ with boost on my cheap Les Paul copy can make it sound almost as good as the real thing, but also gives it a tonal range way wider than any Les Paul I have ever played.
You can also buy shielding kits from any decent luthier supplier (am I allowed to mention names on this forum? Not sure, but typing "Luthier Supplies" into Google will probably work as well as anything....)
But then again, if we were the type to just go out and buy stuff, we probably would not be on this forum. Both the above sites will furnish you with an manner of pre-amps, but where is the fun in that?
Incidentally, the three band EQ with boost on my cheap Les Paul copy can make it sound almost as good as the real thing, but also gives it a tonal range way wider than any Les Paul I have ever played.
Hello all! New here. Saw the original post (and admit I haven't had time to read all pages) so please excuse me if this has been referenced. Try Duncan Amps Tone stack calculator. I am sorry I don't have the link. (try Duncanamps.com) The calculator is very handy. Furthermore, I spoke with a friend who builds beautiful bass guitars and discussed the very same issue I will pass your information along to him. Glad to find this forum.
OPA2134 volume pot problem
Hi, I built Brion55's 3 band eq (with modified center freqs) for one of my 5 string bass guitars as a replacement for the original cheap preamp like a year ago.
It worked fine with the original op-amps (old TL-072's), however they sound synthetic and harsh to my musical tastes and I replaced them with NE5532's... after hearing a loud bang everytime I engaged the boost switch I realized that a bipolar op-amp was not a good choice for that task so I swapped it for the old TL072, and I run it that way until I was able to purchase a bunch of great OPA2134's. The sound is incredible! Brighter, fuller, the bass turned itself into a different instrument! It is much more responsive, low notes sound gutural high notes sound brilliant and not muddy.
The preamp was a little bit noisy with the high knob turned a little bit. So after extensive simulations I decided to change the resistor values for the first gain stage, it had 10k and 4.7k (I left the 1 Meg resistors untouched) and I swapped them to 2.2k and 1k metal film. Noise was reduced to half the original noise floor level with the boost switch engaged, and it is hardly heard without it.
The only problem I noticed is that when I turn the volume pot I hear a scratch noise as if having a dirty pot, I swapped the output op-amp for the NE5532 and this is not heard, any idea of what can be causing this?
Hi, I built Brion55's 3 band eq (with modified center freqs) for one of my 5 string bass guitars as a replacement for the original cheap preamp like a year ago.
It worked fine with the original op-amps (old TL-072's), however they sound synthetic and harsh to my musical tastes and I replaced them with NE5532's... after hearing a loud bang everytime I engaged the boost switch I realized that a bipolar op-amp was not a good choice for that task so I swapped it for the old TL072, and I run it that way until I was able to purchase a bunch of great OPA2134's. The sound is incredible! Brighter, fuller, the bass turned itself into a different instrument! It is much more responsive, low notes sound gutural high notes sound brilliant and not muddy.
The preamp was a little bit noisy with the high knob turned a little bit. So after extensive simulations I decided to change the resistor values for the first gain stage, it had 10k and 4.7k (I left the 1 Meg resistors untouched) and I swapped them to 2.2k and 1k metal film. Noise was reduced to half the original noise floor level with the boost switch engaged, and it is hardly heard without it.
The only problem I noticed is that when I turn the volume pot I hear a scratch noise as if having a dirty pot, I swapped the output op-amp for the NE5532 and this is not heard, any idea of what can be causing this?
I can't answer why the scratchy pot noise went away, but you should note that the NE5532 has a minimum operating voltage of 10 volts.
Very interesting thread.
Thanks for reviving it since I must have missed it the first time around. As if I don't have enough unfinished projects!!!
P.S. Thanks also for the heads-up on the TLE2426 rail splitter by TI.
I never knew they made such a thing. I've always made my own with resistors and an opamp, but this single T0-92 will really simplify things for me. Kudos my friend !
Very interesting thread.
Thanks for reviving it since I must have missed it the first time around. As if I don't have enough unfinished projects!!!
P.S. Thanks also for the heads-up on the TLE2426 rail splitter by TI.
I never knew they made such a thing. I've always made my own with resistors and an opamp, but this single T0-92 will really simplify things for me. Kudos my friend !
Hi head_spaz, I forgot to mention that I play funk mainly with that bass so 9V was not enough headroom for me I'm running it with 2 batteries, I've made some modifications to the circuit to get a more gutural sounding bass since its a cheap 5 string Peavey.
I've shifted the bass center frequency to 15 Hz for example, I changed some resistor values to lower noise levels a lot, obviously the batteries last less than the original circuit but its fine for me since I'm using high quality rechargeable batteries.
The original circuit works fine, you should try it first to find out if it suits your needs and maybe you would want to tweak it a little bit later.
And yes the TI rail splitter is great!
I've shifted the bass center frequency to 15 Hz for example, I changed some resistor values to lower noise levels a lot, obviously the batteries last less than the original circuit but its fine for me since I'm using high quality rechargeable batteries.
The original circuit works fine, you should try it first to find out if it suits your needs and maybe you would want to tweak it a little bit later.
And yes the TI rail splitter is great!
Re: Re: OPA2134 volume pot problem
Do you mean another one? The original schematic has a 4.7 uF cap before the volume pot, the scratch noise is not heard when a TL072 or NE5532 are used for the middle eq and output section that's the weird thing. Any suggestions?
Thanks in advance.
Nigel Goodwin said:
Do you mean another one? The original schematic has a 4.7 uF cap before the volume pot, the scratch noise is not heard when a TL072 or NE5532 are used for the middle eq and output section that's the weird thing. Any suggestions?
Thanks in advance.
Hi everybody.
This is the post I searched for a long time.
Glad to see It's active by now.
I want to customise my noisy P/J Vantage active bass.
I have a better gain directly plugging mics inside te high amp input than with Its active circuit in the low one !
But now I can't switch between active and passive.
I need this functions in both modes:
- Jazz / Precision sweep pot
- Highs / Lows eq control pot (Big Muff style)
- Mids boost / cut pot (is it possible ?)
- Vol
I have a lot of noise on the Jazz position, and a metal plate under this pickup...
Electronic have an octocoupler (is it necessary ?).
I have a couple of TL073 Jfet opamps to do the job and only space for one 9V battery.
Can you help me ?
Thanks
This is the post I searched for a long time.
Glad to see It's active by now.
I want to customise my noisy P/J Vantage active bass.
I have a better gain directly plugging mics inside te high amp input than with Its active circuit in the low one !
But now I can't switch between active and passive.
I need this functions in both modes:
- Jazz / Precision sweep pot
- Highs / Lows eq control pot (Big Muff style)
- Mids boost / cut pot (is it possible ?)
- Vol
I have a lot of noise on the Jazz position, and a metal plate under this pickup...
Electronic have an octocoupler (is it necessary ?).
I have a couple of TL073 Jfet opamps to do the job and only space for one 9V battery.
Can you help me ?
Thanks
Well for the basic newb project, I'd say simply build the Smash Drive with optional tone stack. It's a VERY simple project and with the tone stack incorporated, it's actually a well performing circuit.
http://www.diystompboxes.com/pedals/schems/smashdrive.gif
The smash drive is simply just an amplifier in a dip 8 chip format in need of the most basic controls and components. The circuit is nothing more than the chip designers schematic turned into an understandable picture format with a common, passive, 3 control tone stack added to the output.
With the right tone stack, it makes a really great preamp or even clean overdrive for guitar and bass guitar.
If you want to get your feet wet rather than damp though, go with a basic line driver type design driven by an IC. An op amp is probably the best way to go. You want to start simple which means a passive tone stack like what is used in the smash drive.
The reason this is a better route is the experience and knowledge you gain but also the ability to really tailor the circuit to your demands.
I'd suggest starting here with Duncan's Tone Stack Calculator:
http://www.duncanamps.com/tsc/index.html
And here with distortion basics:
http://www.generalguitargadgets.com/richardo/distortion/index.html
If you build the basic non-inverting op amp gain circuit, which you will need to build a power supply for or go the easy route and simply use 2 batteries which works better anyway, you can slap on the tone stack of your choice and you're done.
http://www.diystompboxes.com/pedals/schems/smashdrive.gif
The smash drive is simply just an amplifier in a dip 8 chip format in need of the most basic controls and components. The circuit is nothing more than the chip designers schematic turned into an understandable picture format with a common, passive, 3 control tone stack added to the output.
With the right tone stack, it makes a really great preamp or even clean overdrive for guitar and bass guitar.
If you want to get your feet wet rather than damp though, go with a basic line driver type design driven by an IC. An op amp is probably the best way to go. You want to start simple which means a passive tone stack like what is used in the smash drive.
The reason this is a better route is the experience and knowledge you gain but also the ability to really tailor the circuit to your demands.
I'd suggest starting here with Duncan's Tone Stack Calculator:
http://www.duncanamps.com/tsc/index.html
And here with distortion basics:
http://www.generalguitargadgets.com/richardo/distortion/index.html
If you build the basic non-inverting op amp gain circuit, which you will need to build a power supply for or go the easy route and simply use 2 batteries which works better anyway, you can slap on the tone stack of your choice and you're done.
Thanks captain, but I think I'm not a NewB anymore since I've already done some boosters and fuzz boxes. Now I need an onboard preamp with a passive/active switch for my bass and possibly as clean as possible! I don't need overdrive onboard. (perhaps a compressor ? :-D)
What is the onboard optocoupler for ?
Thanks for the links and excuse my bad english.
What is the onboard optocoupler for ?
Thanks for the links and excuse my bad english.
Had you checked the links, those were really just the basics to designing a preamp stage, the clipping diodes for getting some distortion is optional.
Call it a booster, call it a preamp, it's still just an amplification stage.
As far as bass goes, I'd avoid compression if you want to remain as clean as possible, compression will screw with your wave form's natural dynamics as well as your pickups response.
Go to the link I posted, check on how to get gain out of an op amp and you slap a tone stack on the feedback loop or the output, it's that simple.
There's your preamp and you can say you designed it yourself
Call it a booster, call it a preamp, it's still just an amplification stage.
As far as bass goes, I'd avoid compression if you want to remain as clean as possible, compression will screw with your wave form's natural dynamics as well as your pickups response.
Go to the link I posted, check on how to get gain out of an op amp and you slap a tone stack on the feedback loop or the output, it's that simple.
There's your preamp and you can say you designed it yourself
I'm also a hobby luthier and am building a 5-string bass. What I am looking for is something close to an Aguilar OBP-1 2-band preamp. Brion, is your 2-band schem close to this? How would I do a proper pickup pan control? How would I incorporate the pan control into the circuit?
Thanks for your help guys,
Corey
Thanks for your help guys,
Corey
I've built a good number of these over the years for guitar and bass (have them on my own instruments too!) I've thought about making a standard PC board for it that could be stuffed different ways for different apps, but just haven't gotten to it. Sounds like there might be enough interest to make it worthwhile.ccreddell said:
I've not seen the Aguilar schematic (looks to be incased in epoxy), but I'm sure it's similar. The 3 EQ caps can be changed to suit your own taste, just remember to keep the 2 on the treble control equal.
As far as a "pan", are you wanting just one pot to pan between two pickups, or two pickup volume controls? The pan is a little harder to do, but I think I have a schematic... somewhere.
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