beginner phaser, flanger and chorus

[teddybear]

any idea?

[CGDARK]

Check out the Zombie Chorus, Ultra Flanger and EasyVibe by John Hollis at: http://www.hollis.co.uk/john/circuits.html

CG

[Mark Hammer]

Time-based effects like chorus and flanger are not exactly suitable for a "beginner".  Phasers are only slightly less complex, because of the need to match components.  You could try the Phase 45, though.  Relatively simple...for a phaser.

[snufkin]

is the flanger 9V ?

and what are the options for a 9v flanger and which is best?


sorry to thread hijack  but this is still a bit relivant

[Mark Hammer]

There is a layout project for a clone of the E-H Electric Mistress over at generalguitargadgets (GGG): http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=123&Itemid=26

Is it the "best" flanger?  Tastes and opinions vary, but plenty of classic tracks have been recorded with it by musicians who likely had many other alternatives to choose from.

The Ultraflanger is one that only a few here seem to have tamed.  To its credit, it has a low parts count and a small footprint.

One of the enduring problems/challenges for BBD chips, whether used in a flanger or chorus or straight delay, is to maintain the stability of the bias voltage needed on the input pin in order to pass signal. Whether you use a trimpot, as some manufacturers do, or a voltage divider formed by a pair of fixed resistors, as other manufacturers do, you need to keep the voltage bias relatively stable, even as the battery voltage starts to decline. Otherwise, the delay signal starts to distort and eventually not make it through the BBD.

In the case of the MN30xx series, some designers let you use a 9v battery OR 9v wallwart, and just figured you'd switch batteries if sonic quality started to decline. Of course, that wouldn't be very long. Others took the route of starting you off with 18vdc so you could make use of a 12v or maybe 9v 3-pin regulator. 18v was way more than you need, but unless you pack the chassis full of AA or AAA batteries, there isn't a whole lot of terrain in the way of "normal" batteries in between 9v and 18v. Regulating at 12v would require at last 14v, so that would let your supply regulation and BBD bias work nicely, until your 9v batteries started to reach around 7v each. Not too bad.

Of course chassis size, and all the attendant costs, such as necessary packaging and shipping costs for different chassis sizes, is part of the cost of production, so you can imagine there was industry pressure (and good justification) to produce a BBD that would bias and run at supply voltages below 9v. The next generation of chips, the MN32xx chips, could be biased and run successfully at 5v. That meant that you could successfully power the circuit with a 9v battery, and the 5v regulator would continue to produce a stable 5v until the battery reached around 7v. The MN3207 will run at 9v. But as I say, the challenge is to have dependable biasing, even as the supply voltage from the battery is waning. As a result, the design objective became that of simulating a regulated supply voltage under all conditions, whether battery or wallwart. Happily, you can regulate batteries too.

Some folks swear by the earlier high supply voltage units, though it's hard to tell if it is the higher supply voltage in the BBD or the rest of the surrounding circuitry (or both) is the source of any audible improvement.

The message running through this is that if your intent is to run it off batteries, certain designs will have advantage over others.  If your intent is to always power it with a wallwart or internal supply, then other designs start to become more appealing (or at least less unappealing).

[snufkin]

thanks mark thats very helpful

somtimes i imagine you have to be at least 4 different people to reply to so many threads and have so much information 
so your all sat there in a room with hundreds of schematics and breadboard helping out

[oldrocker]

If you are going to perfboard any of these :
Ultra Flanger
Zombie Chorus
Easyvibe
I wouldn't suggest them for a first build.  If you're going to make PCB's for them then you might get lucky.  As a perf guy myself those were ones I avoided until I got more proficient at it. 
My first modulation pedal on perf was the Phase 45 and there was some amount of debug but it ended up working great.  I added Univibe mods to it.  I ordered 12 of the 5952's and built a jfet matcher first.  Only two were a good match out of 12 so you might want to go with more if you order a bunch.  I perfed all of the above effects without pre-made layouts.  I laid them out as I built them pretty much like the schematic.  They work fantastic.  All the John H. builds sound great and were fun and challenging.
Take your time do some research and god luck.

[Mark Hammer]

Thanks for the compliment.  I have the luxury of busing it to work every day and being able to flip through my binders of schematics and articles.  All those years of browsing adds up.

More about biasing

The detail I neglected to include in the long post about bias voltages is that, whether trimpot or resistor pair, the bias voltage derived in either of these methods is a fixed fraction of the supply voltage.  When the supply voltage is "in the zone", that fraction is accurate.  Unfortunately, the bias voltage needs to fall within certain absolute limits as well, so as the supply voltage shifts, that fraction becomes inaccurate.  That's why the need to use some sort of regulated/stabilized supply for effects that use a BBD; so that a fraction of a known voltage provides a second "known" voltage.  This is true of all analog delays, chorus pedals, flangers, and time-based vibratos and "ambience" effects.

Bias is also important for FETs too (note that BBDs are actually just a whole stack of tiny FETs and caps), so it should not surprise you all that much that one of the best selling FET-based phasers of all time - the MXR Phase 90 - uses a zener diode to assist in setting the bias of the FETs.  The zener is a 5.1V unit, followed by a bias trimpot.  The trimpot sets the bias to some specific fraction, but the zener dictates that it's a fraction of some fixed maximum (5.1v).  That fixed maximum is low enough that the battery voltage can decline/age by a significant amount without affecting the bias voltage and requiring some internal adjustment to get the phaser working again.  That's how it can be used as a set-and-forget unit.

So, in the grand scheme of things, in both the BBD and FET scenario, there is a need to provide a specific bias voltage to permit functioning.  When the power supply is stable, it is possible to identify that specific bias voltage as a fraction.  The design trick is to either use a stable power supply (on-board adaptor), or, if the unit is supposed to be able to run off batteries, mimic the presence of a stable supply voltage by using either regulators or zeners to set some supply voltage far enough below what the batteries provide, that the bias voltage will continue to be valid for a while.  Happily, with the regulated voltage feeding the MN32xx BBDs often being 5v, and the use of a 5.1v zener in the Phase 90, by the time the battery voltage drops enough to render the derived bias voltage "invalid", that same battery is old enough that the audio portion of the rest of the circuit will also be compromised.  In other words, the bias remains "valid" for as long as you are likely to need it to with any given battery.

I don't know how much of a "beginner" you are.  My normal advice would be to get a couple of simpler circuits under your belt first before attempting any of the modulation effects.  Disregarding the cost, the potential sources of noise in modulation effects are many, and the potential for endless troubleshooting is very high; a discouraging way to start out.  The advice that some offer (and I think it is excellent advice, myself) is to buy a commercial modulation pedal of some kind  - a "beater" as we say in the used car world - and mod it.  That way, all the basics have been taken care of for you and you can use it as a learning opportunity.  It also saves you the annoyance of having to order parts, match them, troubleshoot a home-etched board, drill, etc, etc.  Almost every kid in the world learns to swim with a floatation aid attached to them early on to prevent failure, frustration and potential tragedy. Consider using a commercial pedal as your floatation aid.

[snufkin]

interesting stuff regarding the phase 90


my first pedal was a phase 45 on vero and i did all the matching it was a very good expirance

my third was a phase 90 etched it felt alot easer but i gess that comes from practice 

[magikker]

doesn't GGG have the phase 45 kit on sale right now? That might be the another way to start into modulation.

[soggybag]

I'd vote EasyVibe using the GEO layout. I built this and it sounds pretty good. But it's definitely more complex than a booster or distortion. You need to make some LDRs for it. This is not difficult but is a little tougher than putting a transistor in a socket.