What is the right temp for through-hole stuff like, say, recapping a synth or pulling a chip you don’t want to fry? I see things all over the place from 300° to 550°. It seems like a wide range. Is it just personal preference or are there trade offs? What’s the best for a beginner?
No. 22dBu are actually 13.79V peak with would be over 27Vpp („peak to peak“). Modular circuits are typically designed to handle audio swinging 10V peak to peak. So maximum 5V to the positive and 5V to the negative. I would stick to that to have them work well together will other modules and instead attenuate your input signals. This can be done either with the volume-knob on the Elektrons themselves or by feeding it into a mixer or dedicated input-module with attenuator. I’m a little surprised, that the Elektrons have such a high maximum output… usually modular signals levels are already much higher than the levels of your typical hardware instrument
There are also things like in- and output impedances, which are probably good to be considered, if you want to do things right, but frankly I don’t really understand this stuff yet and probably would tell you something wrong
3 Likes
Solder iron temperature depends on a number of factors, with a high power, quickly regulating iron you can run lower temps than a slower or lower power iron. I used to run my old 25W station at 400 to 450 C, the new 80W is fine at 350… depends on tip shape, pcb area etc (sinks heat, thermal capacitance) and solder wire type and diameter as well. Get an adjustable station and just practice, experiment…
Leaded solders have lower melting temperatures, lead-free solders have higher melting temperatures.
If you are repairing gear from the '80s, use a lower temperature and work your way up. If you are repairing more recent gear, start with a low lead-free temperature and work your way up.
If you are building something new, look at the spool of solder or its data sheet for the recommended temperature.
1 Like
I think I too am a little confused in seeing these figures from the Elektron and wonder if these conversions are truly comparable units (maybe someone else will chime in, too?).
I think as a rule of thumb the “line level” that most audio devices work with is somewhere around 2vpp, and I’ve long heard the conventional wisdom that Eurorack at 10vpp tends to need attenuation to work at line level. That said, moving slowly and conservatively with attenuators and volume knobs, I don’t think you’re in danger of immediately frying something with audio signals, just clipping unless the difference is extreme…
2 Likes
ftr
2 Likes
I managed to make a LED light glow on a breadboard, and dim it with a potentiometer, without destroying the LED! Looking forward to making simple audio stuff =D
5 Likes
My first synth was a Shruthi 1. Assembling it took some time, you have to stay patient/undisturbed/concentrated for a few hours, but I got it right from the first time, and it’s still working flawlessly 9 years later.
Nowadays, I’d definitely go for a XT version.
I then build a PreenFM2. A bit easier to build, no problem neither, but I sold it because I found I hadn’t enough controls at that time.
Before all that, I had build some guitar pedals. A good way to get a project just to try, that doesn’t need that much soldering, and that still is useful later. Distorsion or analog delays are fun.
3 Likes
This is not direct answer to your question. But this information could be useful to better understanding of voltage levels, decibel scales, analog and digital worlds.
I’m not an electrical or audio engineer, but I researched this topic some time ago. Correct me if I’, wrong.
First of all, we’re talking about line level signal.
There are two standard scales for the line level:
- consumer: -10 dBV (0.316 Vrms)
- professional: +4 dBu (1.228 Vrms)
When you see those beautiful ballistic VU meters on analog gear, they should be calibrated to +4 dBu, i.e. 0VU = +4 dBu.
Next, things are a little different in analog and digital worlds.
Analog.
As we already know, analog gear is usually calibrated to +4 dBu.
However, this is common for professional analog equipment to handle up to about +24 dBu before overdrive.
These 20 dB are headroom.
If you want to get as clean sound as possible, you keep your signal about 0 VU and reserve the rest 20 dB of headroom for peaks.
Or you can make your input signal really hot, exceed headroom and overdrive an input of your device if that sounds nice.
Important to know that headroom depends on rails voltage. If you dive deeper into transistors and amplification stuff, you’ll see how it works. Because of that eurorack can’t handle +24dBu, or some guitar pedals sound different depending on power supply voltage (Fulltone OCD and 9/18V holywar).
Digital.
In digital world there is dBFS digital scale where 0 dB is absolute maximum for given bit depth (255 for 8 bits, 16777215 for 24 bits, …). If you overflow this value, you get digital clipping.
Also, there is a lot of difficult stuff about quantization errors and dB per step which gives different dynamic range for different bit depths. You can read more on Wiki (article: audio bit depth).
In context of the question the more interesting thing is A/D conversion.
Relations between dBFS and dBu are often standardized and usually the looks like 0dBFS = +18 dBU (EBU R68, European standard) or 0dBFS = +24dBU (common in US).
These values tell you about headroom of your AD-converters.
If you try to send too hot signal to you AD-converter, you could expect such things:
- you most likely overload analog part before Ad-converter (preamps and so on)
- I’m not sure how AD-converters handle too hot signal. I suppose the either clips at maximum digital value or scales it down somehow. Anyway, I doubt it sounds musical.
Just an example.
My SP404mk2 starts to clip on very low levels of line input. I suspect this is because of 5V power. This is nice it can be powered by USB, but I WANT MORE HEADROOM!
3 Likes
“Ahh, now I understand why I need a ‘Scope”
Fortunately, the big expensive scopes are for RF engineers and will be paid for by their employers. A cheap Chinese ‘Scope in the $150-400 range will be just fine for inspecting how various components impact the signal.
I meant there is dBFS in digital domain and different headroom workflow in comparison with analog stuff.
Not exactly understand how scopes are related to this difference. Could you please explain your point a little deeper?
For me, relatively cheap 2-channel scope with simple signal generator is quite useful for educational purposes.
1 Like
Mostly just a poor choice of quotes on my part.
The point I was trying to make is that if you are interested in observing how gain-staging works between pieces of equipment or within circuits you are DIYing, then a two-channel scope is extremely useful. But these days, the cheap scopes are generally 2-channel and perfectly adequate for audio investigations.
Also should have quoted myself:
1 Like
On the solder temp:
I run my iron around 400C
I use leaded solder. I could go lower, but I like to go quicker with less lengthy contact.
4 Likes
About desoldering to fix old synths: I found this article pretty useful.
3 Likes
Do you really need all of this? You can build about 20 modules whit that? 
I suggest just buy what you need for the project or part you want to build and two of every kind as replacements (short circuiting, etc.)
Maybe instead of a multimeter you want to look for something like that (more useful for audio).
Its more money but i think you will need it
AND DONT FORGET THE OP-AMPS. (TL72, LM3xxx) etc. you will need them for buffering, mixing, etc.
As @diswest says 120$ is not that much looking at your shoping cart and thinking about what you could build with it.
I used mouser.com for most of my parts, but stopped after VCO, VCF, VCA and bought two of https://electricdruid.net/product/cem3340-vco-rev-g/ and https://electricdruid.net/product/as3320-vcf/.
Than i realised im not into eurorack and bought a Digitone as my first “real” synth.
Happy Building 
Edit: Found the source i started with: https://www.allaboutcircuits.com/projects/diy-synth-series-vco/
3 Likes
Messing around with a transistor 
Audio only here:
8 Likes
Dreadbox is reissuing their Hypnosis multi-FX as a DIY kit, just saying.
1 Like
Looks interessting, no soldering. € 248,00 including Shipping & Tax to Germany.
1 Like
Considering a few recent posts here, I thought this might be of interest. Once I’ve completed one or two projects from my “in progress” pile I might try and tackle one of these filters.
2 Likes
Tonight I assembled a Custom Screamer V2 (augmented Ibanez TS9).
I had forgotten how pleasant it is to assemble new gear.
For this I bought a third hand device, with lighted magnifier and 5 arms. And a regulated soldering iron. Good tools makes the job easier.
I plan to change both MD and MM screen at some point (also got myself a desoldering station) but I’ll practice on old defective electronics before I try this. So frightened to break something…
4 Likes