Dirt Bag Parts?

[Scruffie]

For something as complex as the dirtbag you want to make sure your parts are close to spec.

Why? I doubt EHX ever did, the original used early ceramic & mylar caps and still even had some carbon comp resistors in the odd one, hardly tight spec components.

Tollerances don't add up through a circuit.

The only place spec is important is listed on the factory schematic, the 240pF Clock cap should be 5% the 2 x 4.7uF Electros in the LFO should be 10% and a handfull of resistors and caps in the audio path.

And even with those specs... I bet they didn't actually keep to most of them.

Well then...I guess I have better quality control than EHX 

Much as I love them, that's pretty much a given 

Sorry, I didn't mean to call you out but in the interest of keeping information unbiased, I thought I should mention it before it becomes one of those things that spreads as it is not entirely necessary and alot of begginers and further worry a little too much about parts selection when it is not necessary in order to have a great sounding, fully functional pedal.

You can use your bog standard cheap ceramic/mylar caps and standard 1/4 resistors and cheapy electrolytic caps in everything as long as they are rated correctly and have a nice pedal at the end of it that sounds just as good or better to the ear than one built with very expensive components all perfectly matched (unless there is a particular reason for matching or tollerance, such as that 240pF 5% Cap for clock time) it's a matter of personal choice and what an individual is happy with 

Me? I'm a lazy, cheap skate with components 

[madbean]

My DMM (multimeter) has cap measuring which I used to go through a bunch of ceramics to get that 240pF. I actually did two ceramics in parallel. You'd be surprised just how off some of those tolerances really are.

[Scruffie]

My DMM (multimeter) has cap measuring which I used to go through a bunch of ceramics to get that 240pF. I actually did two ceramics in parallel. You'd be surprised just how off some of those tolerances really are.

No doubt, you can get +/-25% tollerances which could make that 180pF or 300pF, enough for significant change in delay time, important parts of the circuit (those marked with a tollerance rating on the original schematic) should be close to the value specified.

But lets not forget your 5k6 resistor that sets the minimum time can be off along with the pot that controls the delay time (Pots tend to have +/-20% Tollerances) so it should all hopefully even out.

[nzCdog]

My DMM does capacitance as well.  Prolly a good habit to test everything, and I used to... but now I usually only double check resistors when they first arrive in the mail
(Yup, too lazy to learn the color codes)  

[masterlk]

So, is there an advantage to using the Capacitance tester kit that the link was posted for over using a DMM to test caps?

[gtr2]

I don't think so.  My DMM just doesn't have a capacitance setting.

[Haberdasher]

So, is there an advantage to using the Capacitance tester kit that the link was posted for over using a DMM to test caps?

My dmm doesn't test for capacitance but I like it otherwise- so that's the main reason I was looking at the kit, plus it's probably cheaper than buying a new multimeter and it might be fun to build.

I have noticed that a lot of dmm's have a narrower range of capacitance they can test for though.  I think the kit can test anywhere from 1pF to 500uF- which I suppose would be nice.  The kit people also brag that having a "dedicated" tester is more accurate.  But someone smarter than me would have to vouch for that.

[madbean]

My DMM (multimeter) has cap measuring which I used to go through a bunch of ceramics to get that 240pF. I actually did two ceramics in parallel. You'd be surprised just how off some of those tolerances really are.

No doubt, you can get +/-25% tollerances which could make that 180pF or 300pF, enough for significant change in delay time, important parts of the circuit (those marked with a tollerance rating on the original schematic) should be close to the value specified.

But lets not forget your 5k6 resistor that sets the minimum time can be off along with the pot that controls the delay time (Pots tend to have +/-20% Tollerances) so it should all hopefully even out.

None of the 240pFs I had on hand measured over about 212pF (these were ceramics). I also did replace my delay pot. The original I put in there turned out to be about 88k. I measured a few other and pulled one that was 99k.

I'll be putting this kind of info in the build doc. It is a more precision build than your average run-of-the-mill TS, that's for sure!

[Scruffie]

My DMM (multimeter) has cap measuring which I used to go through a bunch of ceramics to get that 240pF. I actually did two ceramics in parallel. You'd be surprised just how off some of those tolerances really are.

No doubt, you can get +/-25% tollerances which could make that 180pF or 300pF, enough for significant change in delay time, important parts of the circuit (those marked with a tollerance rating on the original schematic) should be close to the value specified.

But lets not forget your 5k6 resistor that sets the minimum time can be off along with the pot that controls the delay time (Pots tend to have +/-20% Tollerances) so it should all hopefully even out.

None of the 240pFs I had on hand measured over about 212pF (these were ceramics). I also did replace my delay pot. The original I put in there turned out to be about 88k. I measured a few other and pulled one that was 99k.

I'll be putting this kind of info in the build doc. It is a more precision build than your average run-of-the-mill TS, that's for sure!

Do you have the original schematic part tollerances on your redrawn schem/parts list?

If you want I can write them out on your parts list for you, the value of those parts is important (and I agree the delay pot value is even though it's not listed on the schem, I guess they had the pots they had)

There must be a supplier of cheap decent tollerance ceramics or mylars, EHX clearly had access to them 30 years ago.

It definitley is more precision, my initial point was that not every part needs to be measured to spec for it, some do in this build, but a lot of it wont really matter, the audio is just like a bunch of TSs stuck together 

And with the original design process, I doubt they even measured the breadboarding parts let alone production parts other than those tollerances, so who knows what the 'true' values were... plus, where's the fun without variation in sound.

[gtg975n]

I bought and tested two MN3005s from this seller on Ebay: 
http://www.ebay.com/itm/Panasonic-MN3005-IC-4096-STAGE-LONG-DELAY-BBD-1pc-/160561689809?pt=LH_DefaultDomain_0&hash=item256238f4d1#ht_3441wt_754

YMMV, but these ones are the real deal; each has ~300ms delay time and can run at 15V.  I read on another forum that they're pulled from old karaoke machines.  Good luck!

[bigmufffuzzwizz]

I'm excited this project is getting closer!! Even though I have the MN3005's, I may just build the V3205 version and save those for something else.

Here's the DMM I use --> http://www.ebay.com/sch/i.html?_nkw=VC99 It's only 30 bucks!! Comes w/ everything you'll need. Has a capacitance checker but the DIY kit will be way more accurate. I haven't found a cheap DMM that will read pf also. That tester will read 1 pf which is not common. I agree if it could be put in an enclosure easier it would be better.
I don't plan on worrying to much about exact value when I build my DB. I'll probably try buying some larger ceramic value to find the 240pf, like 330pf or something like that.

Me? I'm a lazy, cheap skate with components  

This is how I feel too. I order cheap stuff and always check it! Never any complaints about sound quality from me or people I've built for.

[Scruffie]

Me? I'm a lazy, cheap skate with components  

This is how I feel too. I order cheap stuff and always check it! Never any complaints about sound quality from me or people I've built for.

I buy cheap stuff... but I never check it 

Haven't been bitten once, even with extremley complicated builds (Yes I have actually build an EHX Attack Decay... it took fuckin' ages) which used not just cheap parts that may have been off value, but the wrong valued cheap parts... although that could have put them back in to spec 

Certain builds are gunna need care taken, but for most of the stompboxes we build? Even the BBD ones... i'll keep taking my lazy/cheap way and getting away with it. Unless of course something like matching is required, then it's more of a given.

[pietro_moog]

hi guys.
Xicon is discontinuing the "greenies" serie.
i can't find any 2n7, 3n9, 1n2

any ideas?

thanks

[gtr2]

Where are you placing an order from?  Mouser?

2n7 = 2700pF
http://www.mouser.com/ProductDetail/Kemet/MMK5272K50J01L4BULK/?qs=sGAEpiMZZMvOcEq4GH1AAlEnXbJRHweNYUYRD7DpZzc%3d


3n9 = 3900pF
http://www.mouser.com/ProductDetail/Kemet/MMK5392J63J01L165TR18/?qs=sGAEpiMZZMvOcEq4GH1AAg8ZNcVjbXn7J1rwJ6YmS%252bU%3d

or

http://www.mouser.com/ProductDetail/Nichicon/QYX2A392KTP/?qs=sGAEpiMZZMvOcEq4GH1AAkdEbt1UQq6Wp3xjIRtGqz4%3d

1n2 = 1200pF
http://www.mouser.com/ProductDetail/Kemet/MMK5122M63J01L165TR18/?qs=IKDMbYZLynAiaIzlvnAj0g%3d%3d

or

http://www.mouser.com/ProductDetail/Nichicon/QYX1H122KTP/?qs=sGAEpiMZZMvOcEq4GH1AAkdEbt1UQq6WoHJwgC%2fRIH0%3d

Josh

[pietro_moog]

no, i'm in EU. mouser shipping costs are too much for small orders..
I'll take a look around..