Old 01-20-2014, 05:49 PM   #81
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On that upper limit distortion, well, you could be exceeding the speaker/amp limit, right? OTOH, +5/-5 isn't very much head room for your mic. Now that you've got signal and circuit integrity, what happens to the distortion threshold if you up the supply to, say, 10 or 12 volts? (carefully)
I found that I had made some other silly mistake (the circuit wasn't actually amplifying at all and the distortion was due to signal path). I knew I fixed it when I made the change and the mic started feeding back from the speaker, yay! I was happy that I fixed via using the instruments instead of guessing.

I have built 4 or 5 other small projects since. Looks like the majority of the time has been jig making (I/O etc) and getting used to the build/test process. I can make and sort of know something is going to work much faster now. Biggest thing now is understanding what to do when someone omits something from the schematic (because I should already know most likely) as well as some nomenclature that may require some math that I don't yet remember.

I just made a couple sizeable orders from Amazon and Small Bear so as of tomorrow I'll be fully stocked in a small way. I didn't realize the net was such a plethora of schematics and stuff I can build and use. I also ordered a handful of point to point boards so I could at least wire up a couple simple items before I take it further. This not being able to hit "SAVE" thing in analog is killing me.

I'll report back as I make progress, right now I'm in this endless loop of "ohhh let's make that" and the act of doing so is what is making all the difference aka learning the ropes via doing. Thanks again, this is killer so far!

Student teacher question time:

Many times I'll see schematics with resistor or other cap values completely unmarked and there is always this Vin = (blah blah something r1/r2) type formula at the bottom. I'm assuming this means I need to choose the R values based on what I expect the circuit to do for me (like params in an app) until you tell me otherwise. Actually, here is an example. I was going to build this clipper using an LM741, note the lack of values:


Vout = -Vin (R2/R1)...
Up to Vz + 0.7V

Unrelated to the above... I'm also assuming that since I have separate +5 and -5 power supplies and can combine them to get 10 by making the -5 ground when applicable. I had to do this last night because the project required 12VDC, so I used this method (+6 and -6) summed to get 12 and my voltmeter and the working project agreed. Yes I do know this is different that +5/-5/ground but reminded me of using AC mains to get 110/220. Yea, since it wasn't high voltage I figured the assumption wasn't dangerous to test.
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Old 01-20-2014, 07:17 PM   #82
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I found that I had made some other silly mistake (the circuit wasn't actually amplifying at all and the distortion was due to signal path). I knew I fixed it when I made the change and the mic started feeding back from the speaker, yay! I was happy that I fixed via using the instruments instead of guessing.

I have built 4 or 5 other small projects since. Looks like the majority of the time has been jig making (I/O etc) and getting used to the build/test process. I can make and sort of know something is going to work much faster now. Biggest thing now is understanding what to do when someone omits something from the schematic (because I should already know most likely) as well as some nomenclature that may require some math that I don't yet remember.

I just made a couple sizeable orders from Amazon and Small Bear so as of tomorrow I'll be fully stocked in a small way. I didn't realize the net was such a plethora of schematics and stuff I can build and use. I also ordered a handful of point to point boards so I could at least wire up a couple simple items before I take it further. This not being able to hit "SAVE" thing in analog is killing me.

I'll report back as I make progress, right now I'm in this endless loop of "ohhh let's make that" and the act of doing so is what is making all the difference aka learning the ropes via doing. Thanks again, this is killer so far!
The Karbonator, tearing up the track! Go man, go!

A big YES on cooking up a test jig, as you may recall I mentioned. Besides the convenience, I find having full-size pots and knobs on the breadboard helps me get the right "feel" out of the controls, which I'm picky about when I do a finished build. So doing a jig (pun alert) is time well-spent . . . .

Yes, amazing amount of schemos and info out there. I'd say the internet is a major factor in the Third Wave of DIY electronics (First and Second Waves were 50s, and 70s IIUC). Anyway, wise (and fun) to stock up on parts. Small Bear is just great, and great folks too. However, do consult with me before you go buying any obsolete-ish parts for large $$$.

Meanwhile, go hog-wild, and keep us posted. (And remember to hit CTRL S.)

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Student teacher question time:

Many times I'll see schematics with resistor or other cap values completely unmarked and there is always this Vin = (blah blah something r1/r2) type formula at the bottom. I'm assuming this means I need to choose the R values based on what I expect the circuit to do for me (like params in an app) until you tell me otherwise. Actually, here is an example. I was going to build this clipper using an LM741, note the lack of values:


Vout = -Vin (R2/R1)...
Up to Vz + 0.7V

Unrelated to the above... I'm also assuming that since I have separate +5 and -5 power supplies and can combine them to get 10 by making the -5 ground when applicable. I had to do this last night because the project required 12VDC, so I used this method (+6 and -6) summed to get 12 and my voltmeter and the working project agreed. Yes I do know this is different that +5/-5/ground but reminded me of using AC mains to get 110/220. Yea, since it wasn't high voltage I figured the assumption wasn't dangerous to test.
You are correct, the ratio of those two resistors will determine your op amp gain. (I sense we are quickly approaching a point where you might be a bit surprised at what I DO NOT know, since you were somewhat schooled in this stuff and I never was. ) At any rate, what you've got there is a non-inverting amp, possibly good for guitar due to very high input impedance. Two equal resistors for R1/R2 will give you essentially unity gain; and the more you increase R2 in relation to R1, the more gain you will get. For instance, with R1 one at say, 1K, and R2 at say, 100K, you'll have substantial gain, but this is where your schooling comes in: exactly HOW MUCH gain would you have? (I don't know exactly. See what I mean?)

Also, no coupling capacitors are shown in that schemo, and it's standard practice to use them (unless your specific goals dictate otherwise). For general purposes, you can put a .1uF cap directly from input to pin 3 and directly from pin 6 to output. Ask if you need more info on this. . . .

When you say "clipper" you mean you're going to add clipping diodes to the circuit? Or?

On power supply options: so far the two circuits you've posted are +/- dual supply. And no problem the way you've put your +/- in series, and ignored the ground for the time being. But standard practice for single-supply circuits would be to only use the positive side of your PS, set at the voltage you need, and to use GND, while ignoring the negative side of the PS. Considering almost all stompboxes run on single-supply (a few may not), it's a good thing to get used to. OTOH, you probably already grasp that most circuits don't care what the absolute voltages are, as long as they know where the high, low, and mid points are relative to each other. Something like that. . . .

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Old 01-21-2014, 11:59 AM   #83
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I'm loving this thread. keep bumping it up friends.

btw - I'm young enough to have purchased a Fuzz Face brand new. It does what it says, it's not distortion - it's fuzz, but a soft sounding fuzz.

It incorporated a germanium transistor if IRC. Sorry if I'm a messenger of doom, but other forum posts say the germanium transistor is crucial to the classic sound - they cost an arm and a leg if you can find one.
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Old 01-21-2014, 01:44 PM   #84
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I'm loving this thread. keep bumping it up friends.
That probably won't be a problem because FedEx showed up and I'm now stocked with lots of parts!




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It incorporated a germanium transistor if IRC. Sorry if I'm a messenger of doom, but other forum posts say the germanium transistor is crucial to the classic sound - they cost an arm and a leg if you can find one.
It did... There should be four of them (two sets matched/tested) in the stack of stuff above. I should iterate, this is a hobby I've wanted to do for decades. Only now did I have some spare change to invest so this is really a multi-justified undertaking...

1. Make some pedals for me, cuz I like pedals and making them. Tired of simple purchased ones almost being what I wanted.

2. General electronics. I don't fix/build half the stuff I could because I never had all the needed stuff, either didn't have the tools or the parts or the bench. So this project really is making it so that the only thing stopping me, is me. I should now be able to run into something that needs making/fixing/modding and sit down right there and do it vs. not doing it for some list of reasons. I'm simply making the "why not" list empty.

So for now my activity will be very high and once I get over the hump it'll just become something I use in my everyday life etc. I think I have the parts to start breadboarding the Fuzz Face tonight after work.
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Old 01-21-2014, 02:38 PM   #85
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Well fuzznuts, I missed adding the germainiums to the cart. So they are now on the way but won't be here till later in the week. Guess I have to use whatever I have "in stock" until then. Suggestions anyone of what might be close until my real deal ones arrive?
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Old 01-21-2014, 03:14 PM   #86
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My most useful pedal (apart from delay) is not made to my knowledge.

It's a FlangoDrive, also reversible to a DriveOflange.

let me know when you made one!

I'd like it in green please.
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Old 01-21-2014, 04:28 PM   #87
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I'm loving this thread. keep bumping it up friends.

btw - I'm young enough to have purchased a Fuzz Face brand new. It does what it says, it's not distortion - it's fuzz, but a soft sounding fuzz.

It incorporated a germanium transistor if IRC. Sorry if I'm a messenger of doom, but other forum posts say the germanium transistor is crucial to the classic sound - they cost an arm and a leg if you can find one.
Young enough -- .

Yes, the original FF contained two germaniums, though late 60s/early 70s versions contained silicon. Both sound good to me, the Ge softer as you say, the Si a bit snappier. Old stock germaniums are still available, though getting scarcer and expensiver. You can find them in old broken electronics--portable radios, tape decks, etc.

Do you still have your first Fuzz Face?

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That probably won't be a problem because FedEx showed up and I'm now stocked with lots of parts!

^^^ Uh, that'll do. . . .


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Well fuzznuts, I missed adding the germainiums to the cart. So they are now on the way but won't be here till later in the week. Guess I have to use whatever I have "in stock" until then. Suggestions anyone of what might be close until my real deal ones arrive?
Well, what have you got? (Though probably a shorter list is what you don't got. ) You can do a silicon FF, with either PNPs or NPNs. With Si FFs, a lot of the sound quality depends on the gain (hFE) of the transistor--too high gain can sound very raspy and overwhelmingly fuzzy. Then again, you may want that. . . .

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My most useful pedal (apart from delay) is not made to my knowledge.

It's a FlangoDrive, also reversible to a DriveOflange.

let me know when you made one!

I'd like it in green please.
Yes, I tend to prefer DriveOflange myself, in Bridge-Of-Sighs green.
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Old 01-21-2014, 04:56 PM   #88
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Well, what have you got?
All of them... Not really but I did try to get several assortments and some one-offs. This covers most of them (listed a few ICs and OpAmps as well):



And these....

4 IC LM741EH
2 IC CA3080AE
1 IC ua308HC
2 IC OPA2604AP (OPA2604PA)

Maybe a matched set or two in the above, there may be a few others I'm missing.
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Old 01-21-2014, 05:13 PM   #89
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Ah, fine selection! Among other things, those 2N7000 MSOFETs can make a nice one-xstr buffer. . . .

Do you have a way to measure hFE on your DMM or something? If so, go through your 2N3904s and see if you have any low gain specimens--something around 20-30 hFE is really great. But chances are, if they are newer stock, they'll be in the 100 hFE range. If so, no prob. Here's a pretty reliable site, and an Si NPN Fuzz Face:

http://fuzzcentral.ssguitar.com/axisface.php


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Old 01-21-2014, 05:15 PM   #90
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Ah, fine selection! Among other things, those 2N7000 MSOFETs can make a nice one-xstr buffer. . . .

Do you have a way to measure hFE on your DMM or something? If so, go through your 2N3904s and see if you have any low gain specimens--something around 20-30 hFE is really great. But chances are, if they are newer stock, they'll be in the 100 hFE range. If so, no prob. Here's a pretty reliable site, and an Si NPN Fuzz Face:

http://fuzzcentral.ssguitar.com/axisface.php
Thanks! I don't know but the Digilent instruments may have a way to measure, will report back. Thanks again sir!
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Old 01-21-2014, 05:32 PM   #91
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Young enough -- .

Yes, the original FF contained two germaniums, though late 60s/early 70s versions contained silicon. Both sound good to me, the Ge softer as you say, the Si a bit snappier. Old stock germaniums are still available, though getting scarcer and expensiver. You can find them in old broken electronics--portable radios, tape decks, etc.

Do you still have your first Fuzz Face?...................


Yes, I tend to prefer DriveOflange myself, in Bridge-Of-Sighs green.

I'm afraid the last memory of my Fuzz Face was it coming down on someone's head. A great stomp box with fuck all in it, as I recall.

I felt ripped cos it only contained a little circuit board inside a thing 9 inches in diameter - and that's how I measured things when I was fourteen.


DriveOflange = funky rhythm - but FlangeOdrive for solo surely? That's why it has to be switchable.

Oh, and can I have it shaped hinting ever so obviously like a voluptuous ladies sexual parts please - then you could call it Fuzz Tits. I got the idea from this picture of lots of tits and cocks and arse plugs


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Old 01-21-2014, 06:20 PM   #92
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Seriously though. Danelectro stomps are really cool, and cheap. They really do sound old school, where as Boss are modern sounding. Nothing wrong with Boss, but I love Danelectro cos they do have the Mojo.

I never go anywhere without these little babies

The Fab. Ridiculously simple analog sounding OD stomp that just works.


Cool cat drive. A booster without prestigious acclaim such as the tube screamer, I own a Boss Blues Driver. Once again the cheap Danelectro just works.

I've tried every OD under the sun, and I use these ones. The Boss ones seem designed for modern tastes - more cutting preserving highs. I've owned them all, and these cheap little things have the old Mojo.


Sadly not available in custom colours and not as sexually arousing as an E type, more like a Datsun, but IDGAF.

If interested, I could have a look or take pics so you can see which parts they use.
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Old 01-21-2014, 06:57 PM   #93
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Oh, and can I have it shaped hinting ever so obviously like a voluptuous ladies sexual parts please - then you could call it Fuzz Tits. I got the idea from this picture of lots of tits and cocks and arse plugs

Of all things I've found sexual or suggestive, schematics were never among them. Well, not until now that you've said it, I guess.

Then there's this:


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Originally Posted by Tedwood View Post
Seriously though. Danelectro stomps are really cool, and cheap. They really do sound old school, where as Boss are modern sounding. Nothing wrong with Boss, but I love Danelectro cos they do have the Mojo.

I never go anywhere without these little babies

The Fab. Ridiculously simple analog sounding OD stomp that just works.

[img]<snipt>[/img]

Cool cat drive. A booster without prestigious acclaim such as the tube screamer, I own a Boss Blues Driver. Once again the cheap Danelectro just works.

I've tried every OD under the sun, and I use these ones. The Boss ones seem designed for modern tastes - more cutting preserving highs. I've owned them all, and these cheap little things have the old Mojo.

[img]<snipt>[/img]

Sadly not available in custom colours and not as sexually arousing as an E type, more like a Datsun, but IDGAF.

If interested, I could have a look or take pics so you can see which parts they use.
I've heard lots of good about the DE stuff, though never tried it much. Had the car-shaped analog delay for a while. As for DIYing them, I think they are mostly miniature SMT parts, so too small for my eyes anymore. But that wouldn't stop anyone from doing thru-hole versions if a schematic were available. . . .

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Old 01-21-2014, 07:07 PM   #94
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Of all things I've found sexual or suggestive, schematics were never among them.



Ooh, you are missing out, play one to a beauty and tell her you'll take her to your studio and show her how it works, and what a sound it makes when you plug it in.....




btw, Eric's so called woman tone is the epitome of horseshit stomps. It's just a tone the press hyped up. It was just a guitar plugged into an amp with the treble rolled off.
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Old 01-21-2014, 07:32 PM   #95
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Ooh, you are missing out, play one to a beauty and tell her you'll take her to your studio and show her how it works, and what a sound it makes when you plug it in.....
Come to think of it, that's more or less how I snagged my wife.

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btw, Eric's so called woman tone is the epitome of horseshit stomps. It's just a tone the press hyped up. It was just a guitar plugged into an amp with the treble rolled off.
Ah, so she's only pretty on the outside? Alas, art parallels life.
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Old 01-21-2014, 07:37 PM   #96
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Come to think of it, that's more or less how I snagged my wife.



Ah, so she's only pretty on the outside? Alas, art parallels life.
A. Now you are getting it

B. Not at all, the press were hyping, it's what they do - only you are close enough and know the true beauty. Everything else is meaningless.

C. I have no reference as to what art is, or what art is not art. I can't tell the difference, I don't know the rules.

If pushed I would say everything is art, I'm not clear about how some things are not art....
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Old 01-21-2014, 08:01 PM   #97
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Do you have a way to measure hFE on your DMM or something? If so, go through your 2N3904s and see if you have any low gain specimens
I remembered I have an older meter that does hFE but it'll be a day or two before I can find the dark hole it is hiding in. In the meantime I'm trying to just use two random 3904s just to get a fuzz circuit working. Will update.
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Old 01-21-2014, 08:20 PM   #98
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I remembered I have an older meter that does hFE but it'll be a day or two before I can find the dark hole it is hiding in. In the meantime I'm trying to just use two random 3904s just to get a fuzz circuit working. Will update.

....and then you'll do the flange circuit .....?
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Old 01-21-2014, 10:13 PM   #99
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I remembered I have an older meter that does hFE but it'll be a day or two before I can find the dark hole it is hiding in. In the meantime I'm trying to just use two random 3904s just to get a fuzz circuit working. Will update.
Don't worry about hFE then, it's not at all critical to getting things working, just more of a fine-tuning thing for later. . . .
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Old 01-21-2014, 10:45 PM   #100
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C. I have no reference as to what art is, or what art is not art. I can't tell the difference, I don't know the rules.

If pushed I would say everything is art, I'm not clear about how some things are not art....
Although narrow minds will claim to have it nailed down, art is less about the view than the viewer.
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Old 01-21-2014, 11:22 PM   #101
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Old 01-22-2014, 12:09 AM   #102
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Although narrow minds will claim to have it nailed down, art is less about the view than the viewer.
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Old 01-22-2014, 07:35 PM   #103
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We already have a thread in which we have been talking about sharing personal information. See: 'NSA stuff' for some tips.

Second thought, maybe grandpa wants to tell us what art is...*popcorn*
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Old 01-22-2014, 09:40 PM   #104
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We already have a thread in which we have been talking about sharing personal information. See: 'NSA stuff' for some tips.

Second thought, maybe grandpa wants to tell us what art is...*popcorn*
Dude, you really should get out more.

First you miss the Conan the Barbarian reference, and now you're screwing up A Canticle for Leibowitz.

Literary references are impossible with you if you don't read.
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Old 01-22-2014, 11:21 PM   #105
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Dude, you really should get out more.

First you miss the Conan the Barbarian reference, and now you're screwing up A Canticle for Leibowitz.

Literary references are impossible with you if you don't read.
Differnt worlds, I suppose, grandpappy. Conan the Barbarian and Canticle for Leibowitz aren't in mine. I guess you can imagine me wearing a dunce cap in yours, if it makes you feel better.

Btw, Tedwood was right on. Anything is art, according to the person taking it in. And obviously, you missed the conversation that we had about narrow minds, choosing to inject your blowhardness into something that you missed.

Any way, can't we be friends, friend? What were we talking about, again? Rectifiers and demultiplexers, or something?
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Old 01-24-2014, 04:29 PM   #106
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Excellent, Dave, thanks for joining in. I'm looking forward to your contributions here. From the description of your preamp design, I know I'll learn lots. . . .
For this project, I didn't actually build the preamp. Just the UPS. I have designed and built numerous preamps over the years though.
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I've only done some very lo-fi field recording with a Zoom H2N and with--alley oop--cassette tape. I've done a bit of mic modding: rebuilt the guts of my Oktava MK219 to much improvement, did a Royer tube mod on an MXL2001 (which now needs a better mic capsule http://microphone-parts.com/), built a Shoeps/electret omni from scratch, etc. Curious what LDCs do you use for field recording?
That's some pretty cool mic modding. I'd love to see some pics if you have any.

For most of my ambient and field recording stuff, I use a pair of Rode NT2a's because of their configurability (multi-pattern), high dynamic range, relatively flat frequency response (especially in figure eight which I use for Blumlein config) and EXTREMELY low self noise (this is one of their big selling points).

I'll take some photo's of my UPS build and post them here in a few days. I'll post a scan of the schematics too in case anyone else has a need or use for such a design. The schematic is actually pretty straight forward and most of the parts are readily available. Be warned though, it isn't a fancy computer designed printout. It is a hand drawn (in pencil in case I made mistakes!) design which isn't really optimized for best layout!! I tend to make up schematics as I go and sometimes draw a few versions to make them neater. In this case, I only drew a couple of versions.
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Old 01-24-2014, 04:39 PM   #107
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I haven't read through all the replies here yet but I see some discussion involving designs with germanium transistors. Keep in mind folks that germaniums, unlike silicon transistors, deteriorate over time. An AC128 which could be almost 40 years old might well produce sub par results or even not work at all. They tend to get noisy, lose gain and do other oddball things. So, if your projects suffer any of these symptoms and they use germanium transistors, that is the first place to look when fault finding, even if the transistors measure OK with a DMM.
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Old 01-24-2014, 11:05 PM   #108
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Don't worry about hFE then, it's not at all critical to getting things working, just more of a fine-tuning thing for later. . . .
So, I ended up starting on another one before remembering the axis version you posted...Actually I tried it twice before I realized that particular "cartoony" version wasn't going to work out. I then built the one below and couldn't get it to work either.



Then it hit me, that's at gosh darn dog gone PNP design So I swapped out the 3904s with 3906s because well, the spec says they are PNP and I've got nothing to lose at this point. Also had to remind myself power is -9VDC , fired up the sine wave generator @ 1k and the scope finally lit up with something that I thought might be right, actually, it was farily unmistakeable; maybe this thing is actually working?????

Ran the output to a small 5" powered speaker and it sure sounds like it. Plugged my guitar in and hmm... that sort of sounds like well, familiar. Grabbed the fuzz knob, turned it and yep, that's a fuzz box (quick, smack its ass and cut the umbilical cord ). Then I took it and ran it into my Blues Jr. and I'll be a son of a beach goer this thing really is working.

Here's the problem.... It sounds too good. As in, it sounds too damn good as in I feel like I just invalidated all my other store bought pedals. I seriously am a bit shocked and this wasn't expected. I expected to be tweaking for two weeks just to get it to resemble a respectable tone but instead, I'm afraid to touch it now; I don't want that sound to go away. If something in the picture looks wrong, then that's the new way to do it.

Please excuse the poor form and sloppiness here but I was at the point that I just needed a working circuit, I'll make it purdy later:




I only have the scope screen shot from ealier when I was jamming (not a pure sine wave) but you can clearly see the clipping action in purple (and noise from the unsheilded circuit):




So, thanks again, this is pretty amazing but I'm going on an assumption that since this is with no 1/4 inputs/outputs, no footswitch nothing it's all straight wired, that adding anything, even the expected items to get it in a box, runs the risk of altering what I have now. I suppose even moving the parts to different positions would so maybe I can just encase the breadboard in an epoxy cube as-is and use that.
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Old 01-25-2014, 05:20 AM   #109
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.....
Here's the problem.... It sounds too good. As in, it sounds too damn good as in I feel like I just invalidated all my other store bought pedals. I seriously am a bit shocked and this wasn't expected. I expected to be tweaking for two weeks just to get it to resemble a respectable tone but instead, I'm afraid to touch it now; I don't want that sound to go away. If something in the picture looks wrong, then that's the new way to do it.


So, thanks again, this is pretty amazing but I'm going on an assumption that since this is with no 1/4 inputs/outputs, no footswitch nothing it's all straight wired, that adding anything, even the expected items to get it in a box, runs the risk of altering what I have now. I suppose even moving the parts to different positions would so maybe I can just encase the breadboard in an epoxy cube as-is and use that.
You could always leave the prototype version assembled and build another finished version on a proper PCB or veroboard and if the final version works the same, then disassemble your prototype.
I think you'll find the layout to not be too critical in this particular circuit. Variations in transistor gain would be the most likely point of variation given the bias setup in that circuit. Even then, it looks pretty forgiving.
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Old 01-25-2014, 05:26 AM   #110
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Another tip, if you get stuck with only NPN transistors in future when building a circuit like that, you could use them and just reverse the polarity of the power supply and the electrolytic coupling (input) and bypass (emitter of Q2) caps.
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Old 01-25-2014, 10:54 AM   #111
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Here's the problem.... It sounds too good. As in, it sounds too damn good as in I feel like I just invalidated all my other store bought pedals. I seriously am a bit shocked and this wasn't expected. I expected to be tweaking for two weeks just to get it to resemble a respectable tone but instead, I'm afraid to touch it now; I don't want that sound to go away. If something in the picture looks wrong, then that's the new way to do it.
HA! Now you're a GONER! There's no turning back! (And BTW, that's a good thing, so congrats, nice job. )

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So, thanks again, this is pretty amazing but I'm going on an assumption that since this is with no 1/4 inputs/outputs, no footswitch nothing it's all straight wired, that adding anything, even the expected items to get it in a box, runs the risk of altering what I have now. I suppose even moving the parts to different positions would so maybe I can just encase the breadboard in an epoxy cube as-is and use that.
Don't worry, as Dave points out, the circuit and the layout are pretty forgiving. In fact, there's quite a bit of wiggle-room in terms of capacitor values, bias resistor values, transistor substitutions, etc. My best advice, jot down a schematic of what you've got, then proceed with mods/variations and jot those down each time you come across something you like. . . .

BTW, also as Dave notes, the only difference between NPN/PNP versions is the orientation of the polarized parts. Sound-wise (though some may debate it) there's negligible difference. But in terms of convenience, the NPN version comes out ahead since you don't need a non-standard PS to run it (unless you don't mind using a battery exclusively).

So, Professo Karbo, proceedo with gusto!

PS: when you get your Ge xstrs in hand, there's a nice/useful trick concerning a hybrid Ge/Si FF that I like a lot. . . .
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Old 01-25-2014, 11:04 AM   #112
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HA! Now you're a GONER! There's no turning back! (And BTW, that's a good thing, so congrats, nice job. )



Don't worry, as Dave points out, the circuit and the layout are pretty forgiving. In fact, there's quite a bit of wiggle-room in terms of capacitor values, bias resistor values, transistor substitutions, etc. My best advice, jot down a schematic of what you've got, then proceed with mods/variations and jot those down each time you come across something you like. .
Sweet, maybe its ugly baby syndrome but it sure did sound nice. I have 300.00 pedals that can't supply what I'm hearing; don't me wrong, my T-Rex Moller is a damn sweet Tube Screamer design. I know the Fuzz circuit I built sounds great because when I hooked it up to an amp I played for an hour, had it not been great I'd have instinctively started trying to tweak or fix stuff like I usually do with pedals etc. The real test would be sitting in a mix or with a band.

Quote:
BTW, also as Dave notes, the only difference between NPN/PNP versions is the orientation of the polarized parts. Sound-wise (though some may debate it) there's negligible difference. But in terms of convenience, the NPN version comes out ahead since you don't need a non-standard PS to run it (unless you don't mind using a battery exclusively).
Yea I knew that, the point I was making was the hours I spent tracing and troubleshooting components and wiring not realizing it was a PNP design. If you can get a mental picture of the Chris Farley "I'm an idiot" skits that would have been me at that time.

Quote:
PS: when you get your Ge xstrs in hand, there's a nice/useful trick concerning a hybrid Ge/Si FF that I like a lot. . . .
I have two sets of matched that I don't particularly trust that arrived yesterday. As in they are probably "OK" but they are recently made in china I'm guessing anyway. My hand matched/tested NOS from small bear will be here today or Monday (1 All American and 1 Continental set). Based on what I hear now though, there must be some hair splitting at this point because I really seriously enjoyed what I'm getting out of the 3906s.

However, feel free to pass along whatever as I may swap them today just to experiment. I purchased enough hardware to make 5-6 pedals so what I have may go into a box as-is but this design (by now) only takes me 30 minutes to breadboard.
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Old 01-25-2014, 12:29 PM   #113
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If you can get a mental picture of the Chris Farley "I'm an idiot" skits that would have been me at that time.
No need for a mental picture--I'm the star of that skit at least once a day. . . .

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I have two sets of matched that I don't particularly trust that arrived yesterday. As in they are probably "OK" but they are recently made in china I'm guessing anyway. My hand matched/tested NOS from small bear will be here today or Monday (1 All American and 1 Continental set). Based on what I hear now though, there must be some hair splitting at this point because I really seriously enjoyed what I'm getting out of the 3906s.

However, feel free to pass along whatever as I may swap them today just to experiment. I purchased enough hardware to make 5-6 pedals so what I have may go into a box as-is but this design (by now) only takes me 30 minutes to breadboard.
Well, above all, if you like what you're hearing, you're done. Commit it to hardware. . . .

Hm, as far as I've seen, no Ge xstrs, new or old, are made in China. What part numbers are they?

At any rate, for a hybrid FF, just replace your Q2 with a Ge. With any luck you won't have to adjust your bias. There are several benefits to the hybrid. First, you'll get a bit softer, sweeter tone, closer to an all-Ge circuit. Second, take a look at Q1 on the schemo for a second. See how the emitter is going straight to ground, no resistor? Well, not only is this the most temperature-unstable configuration for xstrs, but Ge transistors are already VERY sensitive to temperature variation. The upshot is, on a very hot or cold day, your all-Ge FF can go so far out-of-bias, it may stop working altogether, or at least sound really lousy.

OTOH, if you keep an Si xstr in the Q1 spot, those problems are mostly solved because Si is considerably less sensitive to temperature. I do this on most all my FF builds. They sound great, winter, spring, summer, and fall!

Hope that's not TMI at this point. Keep the updates coming. . . .
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Old 01-25-2014, 12:50 PM   #114
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Hm, as far as I've seen, no Ge xstrs, new or old, are made in China. What part numbers are they?
M
AC128
K0034

In the above order and the M has a circle around and looks similar if not a Motorola M.

The little shipping bag had a made in China sticker, maybe it was for the bag itself either way probably simpler if I take a picture which I just did:



Maybe I just got screwed on those but seriously, I ordered those to learn from so no hearts broken here and I'm not emotionally attached even if they are wrong; it's truly how I become experienced. I do have an hFE meter now btw.

Quote:

At any rate, for a hybrid FF, just replace your Q2 with a Ge. With any luck you won't have to adjust your bias. There are several benefits to the hybrid. First, you'll get a bit softer, sweeter tone, closer to an all-Ge circuit. Second, take a look at Q1 on the schemo for a second. See how the emitter is going straight to ground, no resistor? Well, not only is this the most temperature-unstable configuration for xstrs, but Ge transistors are already VERY sensitive to temperature variation. The upshot is, on a very hot or cold day, your all-Ge FF can go so far out-of-bias, it may stop working altogether, or at least sound really lousy.

OTOH, if you keep an Si xstr in the Q1 spot, those problems are mostly solved because Si is considerably less sensitive to temperature. I do this on most all my FF builds. They sound great, winter, spring, summer, and fall!

Hope that's not TMI at this point. Keep the updates coming. . . .
Nope, never too much (remember sponge city here). The above makes perfect sense. I'm just lacking knowing all those idiosyncrasies which appears to be where 90% of the curve is. I'll try some of the above for sure.
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Old 01-25-2014, 12:53 PM   #115
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For most of my ambient and field recording stuff, I use a pair of Rode NT2a's because of their configurability (multi-pattern), high dynamic range, relatively flat frequency response (especially in figure eight which I use for Blumlein config) and EXTREMELY low self noise (this is one of their big selling points).

I'll take some photo's of my UPS build and post them here in a few days. I'll post a scan of the schematics too in case anyone else has a need or use for such a design. The schematic is actually pretty straight forward and most of the parts are readily available. Be warned though, it isn't a fancy computer designed printout. It is a hand drawn (in pencil in case I made mistakes!) design which isn't really optimized for best layout!! I tend to make up schematics as I go and sometimes draw a few versions to make them neater. In this case, I only drew a couple of versions.
Ah, thanks for the info. I don't own any RODEnts, but I always hear good things about them. . . .

Photos/schemo would be nice if you have time. No worries, all my schemos/layouts are hand drawn as well.

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That's some pretty cool mic modding. I'd love to see some pics if you have any.
Below are some pix of the electret project. The circuit was published in Recording magazine a few years back. The body of the mic is a Kingsford marker all cleaned out. The capsule is a Panasonic omni with an incredibly flat 20hz-20kHz response. (And, yes those are 2N1305 Ge xstrs, just because.)

I can take a few pix/schemo of the Octava mods later if you'd like.

The Royer tube mic is all based on the article from TapeOp magazine a few years ago. The conversion uses an MXL2001 LDC, removes the solid-state guts and replaces them with a miniature 5840 tube.









Attached Images
File Type: jpg Electret Mic - 1.jpg (37.2 KB, 702 views)
File Type: jpg Electret Mic - 2.jpg (36.6 KB, 466 views)
File Type: jpg Electret Mic - 3.jpg (34.5 KB, 414 views)
File Type: jpg Electret Mic - 4.jpg (32.7 KB, 463 views)
File Type: jpg Electret Mic - 5.jpg (26.1 KB, 411 views)
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Old 01-25-2014, 01:08 PM   #116
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M
AC128
K0034

In the above order and the M has a circle around and looks similar if not a Motorola M.

The little shipping bag had a made in China sticker, maybe it was for the bag itself either way probably simpler if I take a picture which I just did:

Those are strange looking. Before your plug them in, test them. First, use your diode checker to test if they're NPN or PNP. Genuine AC128s are PNP. Next, check the PN junctions as if they were diodes. If they're Ge, you should get a forward voltage reading of about 200-300 mV. Silicon will read about 500-600 mV.

Another thing is, I've got some AC numbers, and I've never seen any in that TO-5 case style before. Usually they come in a TO-1 case like this:


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Old 01-25-2014, 01:32 PM   #117
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How come the ones on that electret mic of yours look similar? Just a curiosity out of ignorance.

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Next, check the PN junctions as if they were diodes.
^School me on that one so I understand the lingo and know I'm doing it right, and secondly in the related article below on the advantages of manually measureing hFE, what am I measuring amps or volts? I was a bit lost as to how to set my meter....

You need to scroll down to #26/27 - "How do I measure gain". I'm going to be a dummy here but I catch up pretty quickly usually as I put the pieces together.

https://www.smallbearelec.com/HowTos...eFAQ/FFFAQ.htm
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Old 01-25-2014, 02:20 PM   #118
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How come the ones on that electret mic of yours look similar? Just a curiosity out of ignorance.
Not at all, it's a good question. The ones in the mic are TO-5 style, but they're American part numbers. What you've got there is an American-looking case with a European part number. IOW, cases, part numbers, and mfg. origin usually will be somewhat consistent. But only somewhat: Japanese and European makes are usually in the TO-1 style case; but US parts vary among TO-1/TO-5 cases. Again, all this is very general--Ge xstrs came in all shapes and sizes over the years. It's entirely possible those you've got are genuine, and I've just never seen them before. . . .

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School me on that one so I understand the lingo and know I'm doing it right
First, think of a diode--it's a semiconductor with a PN junction (the black band is negative/cathode, other side is positive/anode). If you measure with a diode checker, with your probes placed positive to the P-side, negative to the N-side, you'll see a forward voltage. If you reverse the probes you should see an open circuit reading (if the diode is good). For Ge diodes, forward voltage is 200-300 mV, Si is 500-600.

Now looking at a xstr, you've got the same PN junction as a diode, plus one more. For quick testing purposes, you can treat the xstr like a diode by measuring the junction pairs like diodes. So if you have, say, a PNP xstr, you would measure positive probe to either the collector or emitter, and negative probe to the base. Doing this will give you roughly the same forward voltages as a diode of the same material. Also, depending on the whether you get a forward voltage reading or an open circuit, you can determine whether it's a PNP or NPN device. Hope that makes sense.

More in a bit. . . .
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Old 01-25-2014, 02:59 PM   #119
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First, think of a diode--it's a semiconductor with a PN junction
I'm good on diodes in general but PN junction and diode "tester" threw me but I'm hip now. I'm getting 200 mV on one and 220 mV on the other and flow direction verified AKA appears to be working properly best I can tell.
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Old 01-25-2014, 03:14 PM   #120
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Aww, man, now you've done it. I have to get out my soldering iron again and build something.

I think first I'll get a software-based scope, though, just because I wants one, precious, yessss.

I've built some preamps and guitar amps and they all came out okay, and I still have all of MY bits unburnt, so we'll have to see what's next.

Scott
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