@ArthurNemko the board you have is the original layout of the preamp. The circuit should be the same. Do you have a picture of the board that you’ve put together?
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Thanks for coming back to me. Actually, I sorted it out just yesterday! I don't know what else was wrong - I reversed the pot lugs so that clockwise boosts and counterclockwise cuts as it should. I also added a ground wire from pot to pot, just to be sure. After that the EQ worked well. I don't jnow if it sounds as it should as I never had a genuine 2 band. But something happens when I roll off the pots, and not just the first 10% like I stated before.
I then examined the original 3 band EQ and noticed... I forgot to ground the last remaining lug of the volume pot! I feel silly now. But now it works, so whatever!
anyway, thanks for chiming in!Hey guys,
I also tried to build one of these for my 'Ray and I guess I failed. I'm really not an expert when it comes to reading these schematics but I double checked it already and I'm pretty sure it's wired as it should - at least if I'm reading the diagram correctly!
So here's my problem: the volume knob doesn't seem to have any effect at all. I turn it all the way up, all the way down, everything in between - volume is always on and not decreasing a bit when turned down.
Treble pot: first of all, it may be wired in reverse as it cuts when turning it clockwise and vice versa. But there is no (for me at least) audible difference in the first ~90% of turning the pot. The last tiny bit then suddenly adds a lot of high end, zing and also hum.
Bass pot: same here, probably wired in reverse just like the treble pot. Now here, the first ~10% seem to do nothing, so rolled off the bass is cut all the way, then after a very short turn it boosts the bass to the moon! Basically it's the same as the treble pot just inverted, if you will.
Any ideas what's going on? Should I just rewire it completely? Is there a defective part? Like I said, I'm no expert at reading these diagrams, I'm not 100% sure the 9V, the input/output etc. are soldered to the correct ports - but I'm pretty sure...
Later this day, I will ask my father, as he's a electronic engineer, let's see if he can figure it out. Just wanted to ask you guys if any of these 'symptoms' sound familiar and you know where I'm wrong.
Thanks in advance!
From memory ; that sounds an awful lot like how the 2 band Stingray preamp behaves without a battery connected.
You're sure it's receiving juice?
Thank you for sharing that board. I actually built my version and put it in a Stingray-Fivestring-Clone that I built myself. As far as I can hear in my headphones (I have no bass amp at home) it seems a quite authentic Stingray Tone together with a Seymour Duncan SMB-5D. The only problem that I'm having: The volume pot only cuts the volume to 50% - I'm not able to mute the bass. Just double-checked the board and didn't find any issues. Any ideas on what I could have missed?
Edit: Found the issue. The CCW-lug of the volume pot has to go to ground ...
Edit: Found the issue. The CCW-lug of the volume pot has to go to ground ...
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Hi, I have similar with EQ.
Preamp works (i mean it's amplifying and EQ do something), I used 100k log for Bass, 1M log rev for treble and 25k log for volume.
When I'm trying to roll up bass, it feels like first 1/6 of path do nothing and then it's on the max, there's no difference between 2/6 of path and full path.
For Treble it's similar, aprox 5/6 of path do nothing and then it goes to the full.
Does anybody have an idea what can be wrong?
Thank you very much for ideas
Preamp works (i mean it's amplifying and EQ do something), I used 100k log for Bass, 1M log rev for treble and 25k log for volume.
When I'm trying to roll up bass, it feels like first 1/6 of path do nothing and then it's on the max, there's no difference between 2/6 of path and full path.
For Treble it's similar, aprox 5/6 of path do nothing and then it goes to the full.
Does anybody have an idea what can be wrong?
Thank you very much for ideas
I don't have help, but similar behavour of the treble pot (bass control works as expected). Replying in the hope that someone else with better knowledge of the circuit than me has an answer.
I had another weird symptom where with the volume control at 100% there was a lot of high frequency noise (not amplified noise in the signal, but I can only assume originating within the circuit). Turning down the volume a little seemed to make it switch off (abruptly, not gradually) so I placed a small resistor in series before the output and it seems to be working. Any insight into this issue is also appreciated...
Interested in making one of these. The LM4250CN is in short supply. Is there another chip to sub that does the job these days? (Or another version of the PCB with other chip?)
There are many op amps 'better' than the LM4250, which is a (once great) design from 60 years ago. But the thing is to find an op amp that is still available in the same DIP8 format as the LM4250. Last I checked a year ago there were at least 5 or 6 options. And of those the best are LT1097 and LT1012. Both are way quieter, slow but not nearly as slow as the LM4250, decent on power consumption and may be stocked in DIP8 form.
For the LT1097 it needs to have the CN8 suffix in the part #. I just got some, they were backordered for more than 6 months. Don't stall too long!
Link Removed
For the LT1012 look for the DN8 suffix, at Digikey but not Mouser at this time:
Invalid Link Removed
Others that will work. All will be quieter and faster than the original, but choose only if the above fall through:
TLE2061 This is the re-designed TL061. Specs say it is as noisy, LTspice model says it is quieter. Must have 'P' in the part# to be DIP8.
TL061 Ancient chip very good on battery life, some hate it for high frequency hiss, but in this preamp should be decent. And quieter that the LM4250, which most people don't complain about. Must have 'P' in the part# to be DIP8.
TLE2021 Quieter than the original, some noise in the bass region. You might say "I like it, it's really fat (or phat)." Must have 'P' in the part# to be DIP8, like CP or ACP suffix.
LT1637 Last resort but it should work, and like the TLE2021 noisy in the bottom end. CN8 or IN8 suffix.
Last comment--this is important--don't buy from the Amazxx or eBxx sites since they may well be counterfeit. I'd be suspicious of any other source than a real electronics supplier (like Mouser, Digikey, Allied Electronics, Element14, Avnet) that orders directly from the manufacturer. In the case of the above xxx dealers these kinds of parts come from independent vendors and the web site has no control over the validity.
For the LT1097 it needs to have the CN8 suffix in the part #. I just got some, they were backordered for more than 6 months. Don't stall too long!
Link Removed
For the LT1012 look for the DN8 suffix, at Digikey but not Mouser at this time:
Invalid Link Removed
Others that will work. All will be quieter and faster than the original, but choose only if the above fall through:
TLE2061 This is the re-designed TL061. Specs say it is as noisy, LTspice model says it is quieter. Must have 'P' in the part# to be DIP8.
TL061 Ancient chip very good on battery life, some hate it for high frequency hiss, but in this preamp should be decent. And quieter that the LM4250, which most people don't complain about. Must have 'P' in the part# to be DIP8.
TLE2021 Quieter than the original, some noise in the bass region. You might say "I like it, it's really fat (or phat)." Must have 'P' in the part# to be DIP8, like CP or ACP suffix.
LT1637 Last resort but it should work, and like the TLE2021 noisy in the bottom end. CN8 or IN8 suffix.
Last comment--this is important--don't buy from the Amazxx or eBxx sites since they may well be counterfeit. I'd be suspicious of any other source than a real electronics supplier (like Mouser, Digikey, Allied Electronics, Element14, Avnet) that orders directly from the manufacturer. In the case of the above xxx dealers these kinds of parts come from independent vendors and the web site has no control over the validity.
Thanks for the detailed reply! So are these subs just direct drop ins, or any other component tweaking necessary?
And BTW, I do order from Mouser fairly often. With the logged in discount on shipping, no brainer.
Should sub without any circuit changes. All of them ignore pin 8, which on the LM4250 sets the speed and power consumption.
Just remember that it has to be a single op amp, so you can't use for example an old TL062 or a TLE2022, it has to be the TL061 or TLE2021, i.e. the single version. You probably know this and I'm just mentioning it for someone new to opamps.
Just remember that it has to be a single op amp, so you can't use for example an old TL062 or a TLE2022, it has to be the TL061 or TLE2021, i.e. the single version. You probably know this and I'm just mentioning it for someone new to opamps.
Your above posts are great info! Thanks.
Sometimes the TL071 is mentioned as a possible substitute (albeit heavier on the battery). I can readily obtain them here from a reputable hobby electronics supplier. Is it worth getting some of these?
The old faithful TL071 has a real track record and it still the go-to op amp for many (older) engineers. You can definitely use it.
Downside is battery life. Instead of maybe 300-450uA (micro amps) of quiescent current it uses 1400uA (1.4 milli amps) and isn't quite as quiet as the LT1012 and LT1097. But it's still much quieter than the TL061 or the LM4250.
Meanwhile there is another issue I have never seen anyone else mention. There are two manufacturers of the TL071/072/074, Texas Instruments and ST Microelectronics. The TI version is specified for a supply voltage range of 7-30V, whereas the ST Micro version is specified for 6-36V. I'm sure it will still produce some sound below the minimum voltage, but other op amps are specified to run on 4 or 5V and I'd strongly prefer the extra range on a neglected battery.
Downside is battery life. Instead of maybe 300-450uA (micro amps) of quiescent current it uses 1400uA (1.4 milli amps) and isn't quite as quiet as the LT1012 and LT1097. But it's still much quieter than the TL061 or the LM4250.
Meanwhile there is another issue I have never seen anyone else mention. There are two manufacturers of the TL071/072/074, Texas Instruments and ST Microelectronics. The TI version is specified for a supply voltage range of 7-30V, whereas the ST Micro version is specified for 6-36V. I'm sure it will still produce some sound below the minimum voltage, but other op amps are specified to run on 4 or 5V and I'd strongly prefer the extra range on a neglected battery.
Hi, i've just built three of your replicas but i have a pair of questions:
My local electronic components shop gave me the 1.5nF and 550nf instead of 1.8nf and 510nf capacitors. I still haven't received the 1M reverse pot to fully test the preamp but i've installed a temporary 500kOhm pot in reverse wiring just to hear the sound in totally open pot condition and what i can hear is a difference between the other pre ernie ball replicas, because if i don't play hard the zing won't come out and in general i hear a little bit of scooped high frequencies (i'm using a mm4.2 nordatrand pickup). My question is: are the capacitors scooping my treble or is it the pot? The second one doesn't seem a fact to me because if it's all open every pot are not applying any resistance to the circuit so it's like bypassed but i'm a self taught so may be wrong. Thanks in advance.
Yes, it was a cap value problem, changed two caps and now it's working, i also recorded a battle with an 80's 2band eq pre ernie ball Stingray and this one was outstanding, a lot more "louis johnson" boom into that bass frequency
The LT1351 is a great replacement and it sounds better to me. Once I started using them I never went back to LM4250. You won't need the 1M5 resistor at pin 8
I am in the process of wiring up a half dozen of these excellent boards. I must register my thanks to mnats for doing this work that is of major benefit to us MM, Sterling, and SUB bass owners. At the moment, I am attempting to build one of these boards for use in my 2013 SUB 4 string. The original preamp was awful, and that is putting it mildly.
Although my background is in electronics, it's been quite a while since I did any circuit analysis. The first board I built did not function correctly, so I am trying to figure out where I derailed.
I am really missing something. It's late at night and I've had a tough day. Those are my excuses, but I still can't make sense of something. On the circuit board, next to the 9V input, there's a connection labeled Out, which I interpret to mean Output. Here's my problem - according to the schematic, the Output is taken from the wiper of the volume control and goes to the output jack - it doesn't go the circuit board at all. So, I don't understand the purpose of a pc board connection labeled Output. There is no output from the pc board.
Can someone please explain to me where does the wire from the the pcb Output terminal go to, and what part of the circuit connects to the Output terminal? Seems to me, there shouldn't be anything on the board itself labeled Output.
As I see it, the output of the preamp goes through C9 (10 uf) and then to the clockwise connection of the volume control. So, the actual "output" of the board goes to the high side of the volume control.
On the other side of the board, there is a terminal labeled V-CW. That terminal connects to the (-) side of C9. Next to that terminal is a terminal that is labeled V-W. That is the wiper of the volume control. Instead of connecting the wiper of the volume control to somewhere on the circuit board, the wiper of the volume control should connect to the output jack.
The only way this makes any sense to me is if the terminal labeled V-W is connected directly to the terminal labeled Out on the other side of the board. I just now measured the continuity between V-W and Out and indeed it does seem that there is zero resistance between the two terminals. I don't understand the need for this.
I don't mean to be critical; I am just seeking clarification. Wouldn't it have been easier just to eliminate the trace that connects the V-W to the Out terminal? That way, the output jack would get its signal directly from the wiper of the volume control, saving the need for additional wiring and no need for the circuit board trace required by taking the signal from the wiper and feeding it back to the pc board, then across the board to the Out terminal.
Am I missing something? I am hoping someone can shed some light on this for me.
Out is the jack positive out (anode), negative one (cathode) is taken from mass (literally treble pot chassis is connected to mass/ground on pcb) so you should have the control plate doing the job. Because I'm too perfectionist (even on a jazz bass i do this mass wiring) i'm connecting every pot chassis to each one and to negative pole on my stereo jack output (stereo jack is used like on sub ray4 as a cheap switch jack to avoid battery drain when jack cable is unplugged). So you should connect your jack output (+) to "out" and your jack output (-) to mass (or gnd pin, green cable/negative pickup/pot chassis etc...). Everything should be fine. Basically you should do a mass-net and connect to the negative jack out.
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Used this method 3 times now and besides from a little bit amount of "hum" sound coming from my nordstrand mm4.2 (when i'm with headphones lmao, not in my amp nor in my daw) and everything went fine.
Mounted this pre in my ray34, a ray4, and a 1977 MM SR4 with an original pre damaged, so trust me, it works really well.
Mounted this pre in my ray34, a ray4, and a 1977 MM SR4 with an original pre damaged, so trust me, it works really well.
