early discrete circuit effects

[The Tone God]

Are you planning on running all the effects in the case ? It sounds like you are. In that case you might want to add some shielding around each box. With all that exposed circuitry you will have noise issues. Also don't forget your power supply. You will probably want to isolate all the power outputs to reduce various issues. Make sure the power supply is spec'd to deliver everything you need for each effect.

Andrew

[Gilles C]

....Headphone amp: having a heck of a time finding a discrete circuit for one of these!  Any leads?

This could be a start

http://www.redcircuits.com/Page30.htm

http://www.redcircuits.com/Page31.htm


Gilles

[Connoisseur of Distortion]

i see some laurier circuits in there... 

careful. they have a nasty reputation...

[Gilles C]

i see some laurier circuits in there... 

  where

[A.S.P.]

in rch`s long post on the page before.

[Paul Perry (Frostwave)]

Passive ring modulator: 2-transformer passive-type.  What would happen if I made a simple, tunable tone generator to provide the second input, and tuned it to the song's fundamental?

I expect an octave up, with a tremolo effect as the tone generator falls in and out of sync with the fundamental. And plenty of original signal leaking through, plus non-harmonic tones from the non-fundamental frequencies in the song. Go for it!! nice to see someone trying to realise a vision. Will be a long haul... good luck!!

[Pedro Freitas]

Hi!

Nice project, hope you can get what you want.
I have some sugestions for pedals....
Try a simple Idiotwah (T.Escobedo) coupled with a simple transistor peak detector (LED+LDR thing).
Search for old electronic articles on the net. Mark Hammer has some...
Search for old sinth circuits.
Try the Harmonaphone for all transistor octave down. Try varying the frequency of the elecrtic motors
on your tape echo to get flanging and chorusing.
Good luck!

Pedro

[Connoisseur of Distortion]

i meant in the list he posted, not your links

[SonicVI]

Passive ring modulator: 2-transformer passive-type.  What would happen if I made a simple, tunable tone generator to provide the second input, and tuned it to the song's fundamental?

I expect an octave up, with a tremolo effect as the tone generator falls in and out of sync with the fundamental. And plenty of original signal leaking through, plus non-harmonic tones from the non-fundamental frequencies in the song. Go for it!! nice to see someone trying to realise a vision. Will be a long haul... good luck!!

If it's a studio effects unit why not just use a single VCO output from a synth?

[Peter Snowberg]

With a case like that and everything integrated, consider using SPST stomp switches and little relays to do the actual signal switching. The "brute force" way to do that would be with something like  a 25 conductor computer cable with DB-25 ends. DB-25s were used on teletypes so that should be OK with the old-tech thing.

If you use connectors, you don't have to worry about the cable too much as it can be easily extended or replaced as needed. Using a couple wires for power and ground could give you up to 20 stompswitches. It's overkill, but it uses standard off-the-shelf cables you can get anywhere.

That approach gives you a small profile remote system.

Two transistor flipflops could be also be used along with momentary switches like Boss does. That way you could have a pushbutton on the suitcase to toggle effects too, but then the footswitch wouldn't have status lights on it. Hmmm...

I like the idea of modern components working in tandem with vintage ones. Modern stuff does the switching stuff really nicely and it's cleaner to switch with signal relays than lots of wire and mechanical switches.

If you're really onto "old school", this is required reading:
http://www.analog.com/library/analogDialogue/archives/philbrick/computing_amplifiers.html

Download the whole thing and save it for later use. 75M

[rch427]

Steben -- I guess I was misinformed about the earliest Tone-Benders; from the reviews I read on Harmony-Central, I thought they were more of an overdrive effect than just waveform clipping.  OK, then it looks like I'll want to do a separate, clean overdrive unit.  What is "...the fameous !discrete! soft compression opamp of Joe in a tube screamer circuit"?  Who is Joe, and is this an op-amp circuit or discrete?

ASP -- Yeah, sorry, I must've missed that earlier mention of the auto-wah.  Thanks for pointing it out.

Col -- thanks for the tip; on your recommendation, I just picked it up at the local Borders Books.

Tone God -- How would you recommend dealing with shielding the units?  Copper sheets lining each module's compartment, grounded to the case, or what?  And how about shielding the power lines going to each effect?  Shielded cable (likewise grounded), or what?

Gilles -- thanks for the link to the headphone amp schematic!  The second (discrete) one is powered by 3vDC.  How would you recommend dealing with that, given that the other circuits are 9v? 

Commoisseur of Distortion -- your "Laurier Circuits" reference went right over my head.  What's the story with them?

Pedro Frietas -- thanks for the info about the Idiotwah--that looks like just what I need, so long as I can figure out the other part of the circuit (the peak detector).  I haven't been able to find anything about the Harmonaphone through Google, tho'.

SonicVI -- do you mean that I should attach the effects unit to my synth, or just build a separate, self-contained VCO?  Will a single VCO really do what a ring mod does? 

Peter Snowberg -- Thanks for the idea about using transistor logic gates for the switching.  And thanks for the link to that book on Amplifiers, Computing and Everything.  I now have my reading set for the next 10 years now.

Thanks again to everyone for the continuing good advice, and for the patience with my hare-brained scheme.  BTW--a friend of mine in the Netherlands is sending me a shoebox of germanium transistors he's been hoarding for years now.  Looks like I'll be spending some quality time with the transistor tester when they arrive.

-- Robert

[Steben]

look at the second "project forum" - the discrete opamp replacer.  That should make lotsa stuff (orange squeezer) slightly more possible...

Thanks!  What's such a big deal about using 3 transistors, a diode, a cap and 6 resistors instead of an op-amp?  Making that would take very little time, and only cost a few bucks.  And to all the nay-sayers: note where the author of that post wrote "It (the discrete circuit) overloads more gracefully than IC opamps"?  I'm not the only one who prefers the sound of discrete circuits.  It looks like quite a few folks in that thread agree.

I was referring to Joe Davisson's discrete soft-compression opamp. You already saw it 
With this you can make a tube screamer - like overdrive very easy. It will probably sound more pleasant than a stock IC as overdrive ISN'T about hifi linearity... Remember all TS - pcb's use dual opamps, so you need a (simpler) design.

[The Tone God]

Tone God -- How would you recommend dealing with shielding the units?  Copper sheets lining each module's compartment, grounded to the case, or what?  And how about shielding the power lines going to each effect?  Shielded cable (likewise grounded), or what?

Copper would work. You could also use metal duct tape, not the cheap plastic stretch type of duct tape. The problem is the metal duct tape is aluminium which you can't solder to. The copper you would be able to solder too. Also some tape will not conduct through the glue backing so layering the edges of tape on top of each other will not guarantee a connection amongst the various strips of tape.

You can get around the problems by lining the effect case with tape length wise meaning the end of the tape comes out the top of the box. With the tape sticking out if top of the effect box you can wrap the tape around the top lip and attach your face plate thus making a connection to all of the tape through the face plate. Looking at your drawing the face plate will be metal which I assume will attach to a frame of some sort inside the carrying case. If you ground the frame the effect's faceplate attaches to you will ground the tape and shield the effect box. Make sure to test the tape/ground connection with your multimeter after each case is done.

If you will have any transformers in the system say for your power supply you might still want to build the power supply case out of steel. You can use thin sheet metal like that of a metal stud or duct work. Steel will keep EM noise (AC hum) out of the rest of the system. Ground the case of course.

As for power cable I wouldn't worry too much about using shield power lines. Power typically picks up little noise during it's travel. If you got the wire already then go ahead as there will be little consequence but otherwise I wouldn't bother. You still might want to look into a isolated power supply system though.

Hopes this helps.

Andrew

[Connoisseur of Distortion]

the laurier circuits are pretty famous for working sub-par or not at all. from what i understand, their vibrato is actually a tremelo, and people very frequently have difficulty getting the circuits to work. i was recently looking into vibrato circuits, as i am interested in trying to make a pseudo chorus using one...

[octafish]

Re: the discrete opamp tubescreamer. Try searching discrete compression tube reamer in the archive. The tube reamer is a runoffgroove circuit, and even if you don't find the full schem incorporating Joe's opamp, its pretty easy to sub it in. While not really necessary with the reamer, I'd recommend breadboarding with an actual IC to see if you like the general sound of the circuits before going and building a full discrete version, especially if you where to try to do an exact copy of an opamp rather than a simplified version like Joe's. You don't want to spend a whole bunch of time on a project to find you are dissatisfied with the sound of the actual circuit.

Re: The ring mods. You'll need some sort of pretty beefy booster to amplify your guitar signal for a passive ring mod, normally I'd recommend an opamp or a 386 amp but in your case once you get the headphone amp sorted maybe you could use that? BTW in my experience a simple booster like the LPB-1 didn't cut it.
      Also have a good look at the green ringer and the second half of the RM octavia, pretty similar huh? The green ringer IMHO isn't really very ringmoddish, Its sort of like splitting a signal and feeding it into both carrier and modulation inputs, (Actually thats ecaxtly what the Tychobrae does even to the point of incorporating a transformer).  Before building the RM I'd say build two or three fuzzes (your chosen tone bender, a more subtle fuzz face and something truely offensive, the univox square wave?) and the ringer, you'll find a bunch of RM like tones in those combinations.

Congrats on the tape echo.

edit: Are you going to build a patchbay for this? Seems to me you would want to vary your effect order quite a bit.

[Peter Snowberg]

[Gilles C]

Connoisseur of Distortion, I agree with you that "some designs" are to used with care . I was affraid that Red Circuits were mistaken for one of those...

I like discrete Red Circuits, an I wish he was doing more designs specially for guitar 

rch427, I sent Red an email to know his feeling about using it on 9V, both because I don't have time to do it myself, and because he knows his circuits more than us...  We'll see.

Gilles

[bioroids]

Sustain: this modified Roland unit http://members.shaw.ca/roma/sustain.html

I build this a few years ago... the sustain is good (not infinite though) and the sound is sligtly distorted (not in a way that I liked). I added a transistor stage after it and I got huge distortion combined with the sustain: i did use that effect some time.

But the sustain alone didn't impressed me. Could have been my build anyway.

Luck

Miguel

[tiges_ tendres]

I have a schematic for a tube screamer/tube bender style of overdrive that goes from ac 15 to marshall stack that operates with four trannies and '0' opamps if you are interested?

let me know

[petemoore]

  Discrete OA 'socket matcher' [Opamp circuit 'plug'?]
  I built a discrete OA using stamp sized perf, and soldering solid core wire leads [like 1/2w resistor leads, straight down [about 1/4'' long to stick in an IC socket], I built the transistor OA circuit on the perf into a pattern matching an 8pin IC socket, then it could be plugged in where a single opamp would be.
  I decided this might make debugging easier because I could take the OA and place it where I know an IC opamp works. It Fired right up.
  IMExperiment, I used a DS-1 clone [the bulk of the method might not fit in a Boss box] and inserted the "D.OA in the circuit, and it provided certainly a different sound and somewhat less gain that the IC.