Messages

I Googled but didn't find the original article about the Flatline.  Does anyone have the link?

You've probably found this:
http://www.hollis.co.uk/john/circuits.html  (http://www.hollis.co.uk/john/flatline.jpg)

I don't know it there's more from John Hollis himself. But here's some additional information:
http://www.aronnelson.com/gallery/main.php?g2_view=keyalbum.KeywordAlbum&g2_keyword=john+hollis+flatline+compressor+vero+layout+ulysses&g2_itemId=6537
http://www.geofex.com/PCB_layouts/Layouts/flatline.pdf

Nice work!

Absolutely with you there Kothoma, if you try it and prefer it then use it.  Personally I have always used the tonestack approach only because it does what I want with little fuss.  Consequently I have little experience of using a Baxandall setup in this area.  I have used them many times in other non-guitar related audio equipment where they are a standard and do a great job.  I have heard it said that they sound too smooth and "sterile" for guitar work, possibly because of their reliance on negative feedback, but that would not account for using them in passive mode as you have pointed out.  You have more experience than I do as to whether that is true as you have used them.  I should have made it clear that I was speaking mainly from the point of what I had been told regarding that matter.  My apologies.

No need for apologies. Perhaps I should add that one thing to consider with Baxandalls for guitar pedals is that it is often a good idea to shift the center from the standard 1kHz down a bit towards say 700Hz.  Maybe that's why the hi-fi version sometimes is considered inappropriate?

That's a strong claim in need of proof.

You're quite right there Kothoma, but I would maintain the proof is in the simple circuit action.  All of this circuitry has been around in exactly this form for 40 years!

Hm, I still don't see how that would prove that a Baxandall isn't "suited" as tone control in guitar related circuits.

I've heard that the tonestack is prefered because it has less volume drop than a Baxandall, and that it needs less components.
This would explain the continued use from an engineering stand point.
And I like it in guitar amps to shape the basic sound.

As for pedals, now that's something completely different. Here I prefer a Baxandall from a musicians stand point. Just my personal choice.

it utilises feedback from the collector of the third transistor.  It is not in any way in passive mode

Ups. You're right. Pardon my confusion.

American overseas shipping is brutal.

Huh? Free shipping is brutal? See here: http://www.madbeanpedals.com/forum/index.php?topic=9587.0

http://www.tonepad.com/project.asp?id=18 (MXR Noise Gate $14.00)

Why? Plenty of other pedals get cloned and offered as pcb's. What makes the Decimator so protected?

Most pedal circuits aren't patented, and can't be, but the Decimator is.

Seriously?  If its not possible to patent circuits, how could they do it with the Decimator? Especially since I came across two PCB vendors who were selling boards for it?

I didn't say that. Just that most can't be patented, and that's because they are in essence copies of copies, with minor changes, irrelevant for the patent office. Well, if Maxon had applied for a patent for TS-type diode soft clipping in 1974...

The Decimator uses a novel method of adaptive release times and ISP owns a patent for that (afaik).

Why? Plenty of other pedals get cloned and offered as pcb's. What makes the Decimator so protected?

Most pedal circuits aren't patented, and can't be, but the Decimator is.

You're certainly aware of the following fine pages:

http://www.electronics-tutorials.ws/filter/filter_7.html
http://sound.westhost.com/articles/active-filters.htm
http://www.rane.com/note122.html

http://www.sound.westhost.com/project150.htm (Wien Bridge Based Parametric Equaliser)
http://sound.westhost.com/articles/state-variable.htm

Thanks for the update. I guess you're right, with all the different options clear labels and easy access to the pads are preferable.

The layout sizes seem very acceptable to me. I'm curious to hear what your testing shows.

Other topologies: MFB bandpass, inverting (Wien bridge) bandpass, and SVF come to mind. Any others?

Moosapotamus discontiniued ada

Indeed.

http://www.madbeanpedals.com/projects/index.html
  http://www.madbeanpedals.com/projects/CurrentLover/CurrentLover.pdf
  http://www.madbeanpedals.com/projects/Collosalus/docs/Collosalus.pdf

http://lectric-fx.com/product/flintlock-flanger/
or  http://moosapotamus.net/ADAflanger-MN3007.html

http://www.tonepad.com/project.asp?id=54
http://www.tonepad.com/project.asp?id=26

Using the 1M for the depth which I would assume is for the number of repeats

No, that's for the vibrato depth.

the feedback 25K pot

That one controls the number of repeats.

Is it normal to only get 1 repeat?

No, you are loosing your feedback signal somewhere. Check (audio probe) everything in your path from R17 to R18. It's either a bad component, a solder bridge to ground, or some discontinuity.

Very nice execution!

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