One thing that I'll point out about this body is that it is very thin at about 1.25" , fitting the preamp in was no problem.
Enjoy the benefits of a premium membership!
Upgrade Account
-
TalkBass has been independent since 1998. Add your voice.
Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
Join free Log in
Want zero display ads or expanded classifieds tools? Compare plans.
The Passinwind Open Source Preamp
- Thread starter Passinwind
- Start date
I always had mixed feelings about the rechargeable battery concept after a few less than impressive DIY attempts. But then I just recently bought a Willvox Lightwave Saber IV off the classifieds here. And I have to say the rechargeable battery arrangement they have works beautifully.
I guess it’s all about the implementation.
If you’re going to do anything with solar, check out this guy’s website and Youtube channel. He’s heavily into experimenting with solar cells, super capacitors, and what you might call “seriously alt” energy experiments. And he freely shares his hits and misses. It’s not all scifi fun and games either. Some of his projects turned into workable solutions. And like you, he freely shares his work. You might want to try and touch bases with him.
Last edited:
Hi There! I registered recently, because Rallinger showed me this thread and asked me about my opinion from a guitarist perspective. That was the beginning of a journey that took a little longer than expected, but was a lot of fun! It will be a little longer post…
I was attracted by the idea and I wanted to try it for guitar, so I started building up one and tried it “as is” with my Strat. It was already mentioned earlier in a post a few pages ago and I can confirm that it really works exceptionally well with a guitar. I’m an electronical noob, so to say and I let my ears being the judge. Building up that preamp was absolutely easy. To be honest, there is some knowledge in my head, but not that deep to really understand 100% what’s going on in that circuit.
Please, don't wonder about the plaited wires. I’m living in a female-headed household…mother in law, wife, three daughters.. I had to go through this right after I had finished my soldering
So I started playing around with the component values a bit and built up a second one with some differences at some capacitor and resistor values. Sometimes, just because I haven’t had the exact values available, sometimes just to hear what’s happening.
The mid-center-frequency-switch was added, but a little different as described in the wiki. I did it with a 3pdt switch where two capacitors can be switched in series, parallel or short cut one out of the circuit.
Second change were the OPamps. In the second built I used 4062-2/4177-1. Well, also really nice and I do not want to miss one of them. For whatever technical reason it might be better to use the LT1351/1352, my impression (with my pickups and amp) was that the LTs sound smoother or more “American”, while the other OPamps sound more “British”. Really hard for me to describe sound. Don’t know if this is really down to the OPAs used or some other differences due to tolerances in some components. Finally, I added the center-frequency switch to the first built, too.
Since it was hard to do a real A/B comparison I decided not to use them as onboard electronics, but as a stomp box version. This gives me the possibility to use them on all my guitars and also to build this as a two channel version with bypass function to compare always the original signal to different versions after changes have been made. Here it is: I call it "Klangbox"
Totally happy with it and it found its place as a permanent member in my signal chain. And least it has a nice light show for people like me never reading carefully and never knowing where they are. LOL Left Footswitch is the Bypass switch which is shorting input and output of the preamps to ground. Right switch is for A/B switching of the preamps in the box. The color tells the active pots.
A little bigger picture of it.
I did a third version...can't stop it. Especially for my next project. Unfortunately I haven’t taken pictures of the final one, yet. It is a stupid-guitarists-redux-version to fake me the feel of a passive instrument, while keeping the flexibility.
First a trim pot was added to the feedback loop of the preamp stage section. I am going to use this with ultra-low Z pickups and I would like to have a little more amplification. I also adjusted the input stage in regards to input impedance a little lower. Still fine. I dropped the bass pot and replaced it with resistors directly on the PCB. Just a little boost there. I replaced the mid-pot with a 2pdt switch, also with metal film resistors, which is now acting a little alike a mid-cut/neutral/mid-boost-switch. This picture was done somtime in between...
The resonance pot was also replaced by a switch to have a low/medium/high response at the chosen frequency. The Frequency pot is unchanged and gets a “Tone” knob. The volume pot sits after the PCB.
The bottom line is a two knob – two switches control plate. This is the max I am able to handle while playing. Let’s see if this works out as I'm expecting. It will take a while. My build process is more in the timeframe of plate tectonics.
I have only two comments of what I could think of beeing a nice improvement. Two holes for installation of the PCB. Would be a nice benefit even for installation in a guitar cavity. More reliable than double sided adhesive tape. Second, is there a false polarity protection in the schematic? You see, that's how deep my understanding is in electronics... I added a little diode in the battery clip, but would prefer to see that on the board.
@Passinwind : Thanks again for all the effort you took to develop this one! Really appreciate it. If you don’t mind, I would like and post this also in a German luthier forum in their electronic section. Please let me know if this would be ok for you as long as I’m always referring to this thread.
Cheers
Micha
I was attracted by the idea and I wanted to try it for guitar, so I started building up one and tried it “as is” with my Strat. It was already mentioned earlier in a post a few pages ago and I can confirm that it really works exceptionally well with a guitar. I’m an electronical noob, so to say and I let my ears being the judge. Building up that preamp was absolutely easy. To be honest, there is some knowledge in my head, but not that deep to really understand 100% what’s going on in that circuit.
Please, don't wonder about the plaited wires. I’m living in a female-headed household…mother in law, wife, three daughters.. I had to go through this right after I had finished my soldering
So I started playing around with the component values a bit and built up a second one with some differences at some capacitor and resistor values. Sometimes, just because I haven’t had the exact values available, sometimes just to hear what’s happening.
The mid-center-frequency-switch was added, but a little different as described in the wiki. I did it with a 3pdt switch where two capacitors can be switched in series, parallel or short cut one out of the circuit.
Second change were the OPamps. In the second built I used 4062-2/4177-1. Well, also really nice and I do not want to miss one of them. For whatever technical reason it might be better to use the LT1351/1352, my impression (with my pickups and amp) was that the LTs sound smoother or more “American”, while the other OPamps sound more “British”. Really hard for me to describe sound. Don’t know if this is really down to the OPAs used or some other differences due to tolerances in some components. Finally, I added the center-frequency switch to the first built, too.
Since it was hard to do a real A/B comparison I decided not to use them as onboard electronics, but as a stomp box version. This gives me the possibility to use them on all my guitars and also to build this as a two channel version with bypass function to compare always the original signal to different versions after changes have been made. Here it is: I call it "Klangbox"
Totally happy with it and it found its place as a permanent member in my signal chain. And least it has a nice light show for people like me never reading carefully and never knowing where they are. LOL Left Footswitch is the Bypass switch which is shorting input and output of the preamps to ground. Right switch is for A/B switching of the preamps in the box. The color tells the active pots.
A little bigger picture of it.
I did a third version...can't stop it. Especially for my next project. Unfortunately I haven’t taken pictures of the final one, yet. It is a stupid-guitarists-redux-version to fake me the feel of a passive instrument, while keeping the flexibility.
First a trim pot was added to the feedback loop of the preamp stage section. I am going to use this with ultra-low Z pickups and I would like to have a little more amplification. I also adjusted the input stage in regards to input impedance a little lower. Still fine. I dropped the bass pot and replaced it with resistors directly on the PCB. Just a little boost there. I replaced the mid-pot with a 2pdt switch, also with metal film resistors, which is now acting a little alike a mid-cut/neutral/mid-boost-switch. This picture was done somtime in between...
The resonance pot was also replaced by a switch to have a low/medium/high response at the chosen frequency. The Frequency pot is unchanged and gets a “Tone” knob
. The volume pot sits after the PCB.The bottom line is a two knob – two switches control plate. This is the max I am able to handle while playing. Let’s see if this works out as I'm expecting. It will take a while. My build process is more in the timeframe of plate tectonics.
I have only two comments of what I could think of beeing a nice improvement. Two holes for installation of the PCB. Would be a nice benefit even for installation in a guitar cavity. More reliable than double sided adhesive tape. Second, is there a false polarity protection in the schematic? You see, that's how deep my understanding is in electronics... I added a little diode in the battery clip, but would prefer to see that on the board.
@Passinwind : Thanks again for all the effort you took to develop this one! Really appreciate it. If you don’t mind, I would like and post this also in a German luthier forum in their electronic section. Please let me know if this would be ok for you as long as I’m always referring to this thread.
Cheers
Micha
- Dec 3, 2003
- 23,054
- 45,941
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Hi Micha,
Thanks for all that typing and all that detail! By all means post your build thread anywhere you feel like as long as you provide a link back to this thread as well. If you send me a link to the German forum I'll put it in the Wiki here as well.
Those are very worthy suggestions. I need to do a little polarity protection daughtercard for some other projects and I'll make that an option for this open source project as well. I had kind of forgotten about adding it to the main board, which I always intended to develop more once I had sufficient user feedback. Mounting holes would be a really good idea for pedal installed builds especially. I'll take another look at the current board layout and see how hard it would be to incorporate those things.
As far as the opamp differences, the ADA ones have FET inputs and the headroom is a bit less, giving a different clipping waveform and maybe a bit more compressed feel when pushed hard. So "American vs. British" is a pretty decent way of quantifying the differences we'd probably hear in guitar applications.
Switching both midrange caps at the same time opens up some nice options for setting different bandwidths. I'll post details on that in the Wiki once I work through a few suggested starting values.
I'll be doing a few builds for some mandolin playing friends soon. I think I'm going to try a few new tweaks for guitar myself now as well, thanks for the inspiration!
Oh, and finally: who did the circuit boards? They look good in any case, and I love the braided wires. I've been using silicone insulated wiring like you see in radio controlled cars, drones, and so on. That stuff braids really well, and it comes in at least ten colors. It has a lot of strands and the flexibility and resistance to breaking at the stripped section can save some hassle if the board is going to get moved around a lot, as often happens in first builds especially.
......................................................................................................all the best,
I already saw it within a PM but I'm still left with my mouth open for that awesome stompbox! Congrats, Micha!
However I feel a little bit like an idiot ... But since I am finally able to answer at least ONE question here: it was me that ordered the PCB's at allpcb.com and I provided some of them to Micha. Our asian friends are much faster than oshpark at least when it comes to ship to europe and with much fewer shipping costs (shipping would have been 2x the price of the PCB and 3x shipping delay compared to allpcb). Hope that was ok.
Having had the PCBs in hand very fast I had then problems to source the parts and while waiting for them I was covered with work by clients so ... the parts are still waiting here on my desk ready to be soldered. I told that rather often to Micha while he was working but I think this weekend ... ;-)
Thanks for the inspiration and to you Charlie, for that awesome work I'm always impatient to hear with my own ears.
However I feel a little bit like an idiot ... But since I am finally able to answer at least ONE question here: it was me that ordered the PCB's at allpcb.com and I provided some of them to Micha. Our asian friends are much faster than oshpark at least when it comes to ship to europe and with much fewer shipping costs (shipping would have been 2x the price of the PCB and 3x shipping delay compared to allpcb). Hope that was ok.
Having had the PCBs in hand very fast I had then problems to source the parts and while waiting for them I was covered with work by clients so ... the parts are still waiting here on my desk ready to be soldered. I told that rather often to Micha while he was working but I think this weekend ... ;-)
Thanks for the inspiration and to you Charlie, for that awesome work I'm always impatient to hear with my own ears.
Man has a lot been going on here since I last checked in! I’m going to have to order some parts and do up a second one since my first assembly “inna box” got promptly stolen the first time I took it out.
But first I’m gonna have to read through the whole thread just so I don’t miss anything.
Thanks again to C.E. for the generous gift of his time and expertise in order to bring this project and learning opportunity to the TB community.
But first I’m gonna have to read through the whole thread just so I don’t miss anything.
Thanks again to C.E. for the generous gift of his time and expertise in order to bring this project and learning opportunity to the TB community.
- Dec 3, 2003
- 23,054
- 45,941
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
It's fine to use any vendor you want to Ralf. My goal is to make this project as easy and accessible as is reasonably possible. OSHpark used to ship free to anywhere in the world, I guess that's changed now? In my case OSHpark currently takes 8-10 days to my mailbox from the day I order.
I've seen from Micha's builds that I also have not detailed bypass switching options. One more thing for the to-do list.
Hi Ralf,
Uups. Sorry for not mentioning this. In fact that wouldn‘t been possible without your support, too.
Cheers
Michael
Uups. Sorry for not mentioning this. In fact that wouldn‘t been possible without your support, too.
Cheers
Michael
Easy. That wouldn't have been worth mentioning if Charlie hadn't asked. And I only pointed it out for telling other europeans ... however, Charlie, I don't know the actual conditions of Osh. Maybe I didn't see something. But I clearly remember having had some "seriously? Nossir!" moment when I moved to checkout ...
- Dec 3, 2003
- 23,054
- 45,941
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
I'll look into it. A friend in India mentioned that shipping time to where he is might exceed 90 days.
I'd also like to hear about which parts are hard to source in the EC. This has come up a few times with a friend in the UK and I ended up shipping him parts kits. I tried to keep things simple by specifying stuff that Mouser stocks, but it would be great if we could duplicate that one vendor list in a way that works seamlessly for those in Europe, Asia, etc.
Well, we had a discussion on that by PM on end of january if you remember. In my case it was the LT1351 that I ordered end of january and received end of march (ordered it at digikey). But that might have been a temporary problem. I checked it now and they are available.
In general it's more the resistor values in your suggestion that aren't too common here abroad. Not that this would mean too much but previously on this thread, I had never seen such values ...
In general it's more the resistor values in your suggestion that aren't too common here abroad. Not that this would mean too much but previously on this thread, I had never seen such values ...
- Dec 3, 2003
- 23,054
- 45,941
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Thanks, and I still have all those PMs, which I greatly appreciate. I was/am actually hoping that some others might chip in with their experiences on this as well. I general, up to a 10% difference on resistor values is mostly not too critical, especially if all the ones at any given value match each other reasonably closely. Spec'ing something like 261K typically means they will be 1% tolerance or better by default (this would be a Mil Spec value most likely), which is partly why I used that value instead of say 270K. In my own case it also meant I could buy 100 resistors on surplus for a very good price, as a few of my favorite eBay vendors only stock "oddball" values.
Thanks again to you, to Micha, and everyone else who has helped keep things moving along. I've really been enjoying having one of these preamps in my fretted 5 string bass ever since I installed it several months ago. Hopefully I will be able to refine a few aspects more readily from what I've been learning by taking that bass out and playing it through various other people's amps.
Can‘t speak for the whole EU, but there are suppliers in Germany at least for capacitors, resistors and pots like RS Components or Farnell/Element 14. Issue is that you need a commercial account to source there, which I have from an old shop I ran.
Biggest issue was that Analog or Linear do not have a distributor for the German market. I got the Linear parts from the UK. Mouser works, but it‘s a question of shipping costs which is not worth for DIY builders like me.
Biggest issue was that Analog or Linear do not have a distributor for the German market. I got the Linear parts from the UK. Mouser works, but it‘s a question of shipping costs which is not worth for DIY builders like me.
Last edited:
Which of the components do you refer to?
It's a problem if you can't source all the components required at "C", "V" or "R"....
True.
Basically I found all minus the PCB. I did some comparisons between different values for resistors and capacitors and for my feeling you don’t necessarily need to meet them 100%. You can get close (enough) with the components e.g. „musikding“ carries. Again, not the OPs.
I think the most important point for us would be (again) to find a good replacement for the LT1351/LT1352 or ADA4062/4177.
Last edited:
I placed an order for pcb's today. I'm looking to mate this preamp with multicoil pickups. Next to search the components.
I got my ADA replacements for the LT’s from eBay. Search for „littlediode“. They‘re from the UK. Not the cheapest way, but feasible. Theoretically every OP which is compatible from it‘s pinout can be used, but will sound different. I propose to use either the LT‘s or the ADA‘s.
Last edited:
- Dec 3, 2003
- 23,054
- 45,941
- Disclosures
- Designer/Toaster Tech @ Passinwind Electronics
Did you contact an LT/Analog Devices sales rep, or look for direct ordering/free sample info on the LT website? AD owns the Linear Technology brand now.
Unfortunately, I still haven't tried any opamp subs in this circuit yet. If you do try subs I'd highly recommend looking at the output on an oscilloscope to check for parasitic oscillation. That's not a bad idea even when using the spec'ed parts, actually.
