Hi there, first post.
When building pedals does the choice of components such as electrolytic caps matter?
When I built amps before just about all caps in the signal path were nichicons or elna etc.
Guess I'm asking do I use audio grade components or are off the shelf standard variants ok
Thanks in advance
What makes a component "audio grade"?
Quote from: FiveseveN on November 01, 2020, 06:49:33 AM
What makes a component "audio grade"?
I think (unless someone proves me wrong) that "audio grade" is merely a subset of general purpose. Audio is not a very demanding application. I don't think audio grade parts are
better at audio as much as they are worse for tougher applications. In other words, I think it is a marketing term rather than a technical term.
Quote from: EBK on November 01, 2020, 06:56:27 AM
Quote from: FiveseveN on November 01, 2020, 06:49:33 AM
What makes a component "audio grade"?
I think (unless someone proves me wrong) that "audio grade" is merely a subset of general purpose. Audio is not a very demanding application. I don't think audio grade parts are better at audio as much as they are worse for tougher applications.
that is exactly what my teachers told me, the only thing is that some audio grade chips are designed to be slower, like the famous LM308 or the OP07 (those are both not audio grade but they are slow)
cheers, Iain
Thanks for the replies.
Audio grade it would seem was a bad choice of words.
Probably bad examples but all of my volume pots on amplifiers are Alps, using generic pots there gave scratching when adjusting the volume.
If I can use generic pots for pedals that's great as Alps etc. cost a fortune.
Same for capacitors, in an amp I built in my teens I used generic capacitors. Changing these about 10 years later for elna silmic ii capacitors gave much clearer sounding instruments but didn't notice a big change in vocals.
I'll add: I'm looking to build pedals with/for my son. I don't play instruments and the only experience I have is in building HiFi type amps and projects.
Apologies if my word choice isn't the best but I'm unfamiliar with the correct nomenclature.
Quote from: Here2learn on November 01, 2020, 07:57:29 AM
Alps etc. cost a fortune.
You get what you pay for, as usual. Good news is low voltage caps will be significantly cheaper.
In a nutshell, you generally don't need spendy exotic components to make a pedal that sounds as intended. Whether it's to your liking or not is a different issue, but the power of DIY is that you can tweak any circuit to your tastes.
Quote from: FiveseveN on November 01, 2020, 09:43:12 AM
Quote from: Here2learn on November 01, 2020, 07:57:29 AM
Alps etc. cost a fortune.
You get what you pay for, as usual. Good news is low voltage caps will be significantly cheaper.
In a nutshell, you generally don't need spendy exotic components to make a pedal that sounds as intended. Whether it's to your liking or not is a different issue, but the power of DIY is that you can tweak any circuit to your tastes.
Thankyou. We're currently making a shopping list for a couple of pedals he wants to try.
May I ask, do you use all generic components yourself or are there areas where spending extra seems worth it to you?
If there's no need for fancy components costing over 100x generic ones then I won't use them.
I always buy the cheapest film caps that I can, paying attention to the lead spacing and voltage rating (and capacitance, obviously), but ignoring pretty much everything else. For electrolytic caps (2.2μF and up), I do the same. For pF range caps, ceramic are fine, but I will usually look for NP0 or C0G for those. I do have a high quality LCR meter to check my caps before using them though. Potentiometers in my builds are almost always cheap Alpha. I generally buy all my parts from Smallbear and Mouser. Sometimes where you buy your parts can matter.
For resistors, 1% metal film, choosing the cheapest. Watch for volume price breaks. Often, 10 will be cheaper than buying just 1!
Here's my boilerplate response:
1) "Classic effects" were made with plain vanilla carbon comp 5% resistors and the cheapest "elephant-ear" ceramic caps. Good enough for rock-and-roll then, good enough now. Not that one HAS to use them, merely that they were good enough and remain so.
2) If one was:
- attempting to process signals from multiple instruments/sources
- attempting to preserve wide bandwidth in at least one of those signal sources
- attempting to provide the least possible coloration
....then cap choice would likely matter, and maybe even matter a
whole lot. But, for better or for worse, most folks here are processing a single audio source in their pedals, generally a guitar, which has a complex waveform but fairly restricted bandwidth, played into an amp that also provides restricted bandwidth into speakers with a restricted bandwidth.
Now, if your objective was to build pedals for a polyphonic synth that you're using to produce string sounds, or maybe even just a drumbox with digital cymbals, and you're feeding that signal to a P.A. and speakers with tweeters, high-power amps with gobs of headroom, to make those highs really sing, then you'd likely want to start paying attention to component choices. If you're just making overdrives for guitar, though, it's not worth the effort. Buy what's cheap and fits the space on the board.
Chip-choices are a little different, since certain traits of different op-amps may be tailored to specific contexts. So, some draw less current and are preferred for the LFO in modulation circuits, for that reason. Some can push low-impedance loads easily, and are preferred for that reason. Others are low noise and preferred for that reason, and so on. Still others can be preferred in some applications because of their weaknesses that lend a certain quality to the sound. "Better"
can be better in some instances, but not always.
Quote from: EBK on November 01, 2020, 10:53:36 AM
Sometimes where you buy your parts can matter.
Absolutely, usually big stores. I've been caught on ebay a few times before.
Quote from: Mark Hammer on November 01, 2020, 11:22:58 AM
Here's my boilerplate response:
Everything made perfect sense and helped clarify some of the decisions EBK pointed out.
Your point about bandwidth clarified it all quite simply and was something I hadn't realised.
Thanks to all for the replies.
I'll likely have more questions. Likely just as stupid but I'm Here2Learn and looks like I may be doing that the hard way 😁
Nobody said WELCOME! ??
All the classic pedals were made of the cheapest parts. Remember most listeners listened on pocket transistor radios which had even worse parts (because of mass production there were exceptionally cheap parts available). We know that the "FuzzFace", Jimi might go through a case of 100 to find one with "the" sound.
While parts in general have got much better, some have gone further downhill. 1/4 jacks were always a bit iffy; I see some today I don't think will last 3 gigs. Mechanical abuse parts, get good stuff. (Pots are indeed in that class but start with medium-cheap and see how it goes.)
Since you are new to *this* racket, shop the for-pedals parts houses. Small Bear Electronics is excellent, in the US, when his workers are willing. (NYC is not the best place in a pandemic.) He mostly carries a thousand PEDAL parts, not millions+ of cellfone or MRI or military mystery-bits like Digikey/Mouser/Allied. He also sells to medium-size commercial builders, and if a part don't work for purpose they tell him. Tayda and another also focus on pedal-type parts, but keep a larger selection of sometimes odd parts, are lower price but slow or very-slow shipping.
Remember that in hifi-world you only use one preamp at a time. Pedals are more like shoes. A guitar player may have a dozen pedals on the pedalboard, and another two dozen in the closet for various reasons.
Quote from: PRR on November 01, 2020, 04:28:34 PM
Nobody said WELCOME! ??
:icon_redface: :icon_redface: :icon_redface: :-[ :-[ :-[
A tip of the hat to Paul/PRR for being the gentleman. I apologize for my neglect. Sometimes I look at the post count and put out the welcome mat, and sometimes I forget to do that.
Welcome. Put your feet up and relax. :)
QuoteI always buy the cheapest film caps
...
I do have a high quality LCR meter to check my caps before using them though.
Have you noticed polyesters a have lower capacitance at 10kHz than at 1kHz?
Whereas polypropylenes and polystyrenes don't shift much.
Quote from: Rob Strand on November 01, 2020, 08:13:25 PM
QuoteI always buy the cheapest film caps
...
I do have a high quality LCR meter to check my caps before using them though.
Have you noticed polyesters a have lower capacitance at 10kHz than at 1kHz?
Whereas polypropylenes and polystyrenes don't shift much.
Have I noticed? No.
QuoteHave I noticed? No.
I had some maroon dipped capa in my junk parts once that were pulled from CRT monitors. Initially I thought they were polypropylene but after testing them I realized some were polyester. Some could be worked out from the markings but for others the frequency test was a quick way work out what they were. As it turned out a whole heap were just polyester.
(http://www.yuonyu.com.tw/uploadfiles/22/METALLIZED%20POLYPROPYLENE%20FILM%20CAPACITOR%20(DIP/mpp-l.jpg)
"Audio quality" is a marketing ploy designed to separate the punter from his money (as others have mentioned, "audio" is the bottom of the barrel when compared to "military" and "medical"...). Just remember that we're playing rock'n'roll with guitars and noisy amps. :icon_twisted: IMHO, the only things worth spending money on "quality" are the mechanical parts: jacks and switches, i.e. things where keeping the electrons happy is not on the top of your list.
I heard Dick Dale only used surfers mount components in his amps.
It's only Monday and Rob wins the internet for this week. :icon_biggrin:
Oh Rob, you're such a Showman! ;)
I see what you did there, Mark. A worthy runner-up. :D
Quote from: PRR on November 01, 2020, 04:28:34 PM
Nobody said WELCOME! ??
All the classic pedals were made of the cheapest parts. Remember most listeners listened on pocket transistor radios which had even worse parts (because of mass production there were exceptionally cheap parts available). We know that the "FuzzFace", Jimi might go through a case of 100 to find one with "the" sound.
While parts in general have got much better, some have gone further downhill. 1/4 jacks were always a bit iffy; I see some today I don't think will last 3 gigs. Mechanical abuse parts, get good stuff. (Pots are indeed in that class but start with medium-cheap and see how it goes.)
Since you are new to *this* racket, shop the for-pedals parts houses. Small Bear Electronics is excellent, in the US, when his workers are willing. (NYC is not the best place in a pandemic.) He mostly carries a thousand PEDAL parts, not millions+ of cellfone or MRI or military mystery-bits like Digikey/Mouser/Allied. He also sells to medium-size commercial builders, and if a part don't work for purpose they tell him. Tayda and another also focus on pedal-type parts, but keep a larger selection of sometimes odd parts, are lower price but slow or very-slow shipping.
Remember that in hifi-world you only use one preamp at a time. Pedals are more like shoes. A guitar player may have a dozen pedals on the pedalboard, and another two dozen in the closet for various reasons.
Thanks for the welcome, and the analogy.
Not quite sure how long I'll be welcome though lol
I hadn't thought about that but it makes sense that pedals would be a bit like shoes.
I see by the replies below yours folks round here have a sense of humour.
Not used to that in electronics but it's great to see
Edited to add:
Thanks for the heads up on the stores. Very handy to know and their prices aren't that bad.
It's definitely looking like the mechanical parts are the higher priority.
Very glad to have found this forum as I'd have spent a fortune where it wasn't needed
Quote from: bluebunny on November 02, 2020, 03:35:03 AM
IMHO, the only things worth spending money on "quality" are the mechanical parts: jacks and switches, i.e. things where keeping the electrons happy is not on the top of your list.
Thanks.
We're looking at Neutrik jacks currently.
Are there any jacks you'd recommend?
I'm a fan of Switchcraft jacks, particularly the No. 11 open frame jacks.
(https://www.amplifiedparts.com/sites/default/files/uc_products/w-sc-11_copy.png)
Quote from: Here2learn on November 02, 2020, 01:30:17 PM
I see by the replies below yours folks round here have a sense of humour.
Not used to that in electronics but it's great to see
Forty odd years back,
Electronics Today magazine used to have a regular feature with tech-related cartoons. I think you'll agree that, during the intervening 40-some years, the quality of humor has improved.
(https://i.imgur.com/W7ug0Jl.png)
There is a visual representation of capacitor linearity here:
http://diyaudioprojects.com/mirror/members.aol.com/sbench102/caps.html
that shows ceramic capacitors have a large nonlinearity because the ceramic element acts like a a ceramic headphone and flexes in response to applied voltage but the others are quite linear. It can also act as a microphone and feed a signal due to vibrations into the circuit. Ceramic is best used at radio frequencies.
Another parameter to watch out for is dielectric absorption. This is measured by charging up a capacitor with DC voltage, shorting it out, removing the short and measuring the voltage. The closer you get to zero the better and once again, polypropylene is best. The dielectric can form an electret, the electrostatic equivalent to a permanent magnet. Electret microphones are quite common. Normally the value of dielectric absorption is negligible but if a circuit is sensitive to bias voltage, this could be an issue.
But polyester is quite common and almost as good as polypropylene.
Waxed paper capacitors were quite common for a long time but they develop electrical leakage after a while due to moisture absorption. Sometimes these are encased in plastic like the notorious bumblebee capacitors so called because the values are identified by coloured rings like a resistor. These are known to split down the side of the plastic case and let moisture in.
There is a decent wikipedia article on capacitor dielectrics here:
https://en.wikipedia.org/wiki/Capacitor_types