Harmonic Trem options

[samhay]

>maybe I should knock up a quick StompLFO harmonic trem?

https://www.diystompboxes.com/smfforum/index.php?topic=103714.0

[Joncaster]

>maybe I should knock up a quick StompLFO harmonic trem?

https://www.diystompboxes.com/smfforum/index.php?topic=103714.0

Another edit:
Sam, is your project still available?
Can't find any files on that thread of yours.
Thanks

Last edit, i promise:
Found it! sorry, didn't read far enough, doh.

[Joncaster]

Hooray, I can source all the parts locally for your Anharmonic Trem, Sam.
I'll give that a try first, I think.

My current ability to import stuff (like a smallbear order) is severely limited by our import laws (max 3 shipments a year without a Code, and it's a heavy process to get a code).

[ElectricDruid]

I'd certainly be interested to see what you came up with ElectricDruid.

I'm putting together a Tremulous Lune at the moment which is what the VTL5C3 is for, but I'll probably be itching to play with a new tremolo by the time you're not quite done with the first design ;-)

Well, David Rolo's Twin Peaks (or the Delky PCBs Cherry Pie based on it) is a fantastic bit of work and sounds great, but it has literally *all* the bells and whistles, which makes it a bit complicated for some people. The TapLFO chip has a lot of options and controls if you use them all. So I was just thinking of a simplified version using the StompLFO instead - keep the harmonic trem audio path, but use a simpler LFO to reduce the knob and parts count to something a bit easier. It'd still have eight waveforms and tap tempo, so it wouldn't exactly be under-specified, even like that!

[soggybag]

You could also build the Tremolomatic-x from stompboxology. I built two of them. They sound great. The project uses NE570 no need for LDRs. There was a PCB layout here way back when, it could be 10 years or more.

http://moosapotamus.net/files/stompboxology-mo-tremlo.pdf

[Joncaster]

You could also build the Tremolomatic-x from stompboxology. I built two of them. They sound great. The project uses NE570 no need for LDRs. There was a PCB layout here way back when, it could be 10 years or more.

http://moosapotamus.net/files/stompboxology-mo-tremlo.pdf

Thats a great resource, thank you!

[samhay]

Hooray, I can source all the parts locally for your Anharmonic Trem, Sam.
I'll give that a try first, I think.

My current ability to import stuff (like a smallbear order) is severely limited by our import laws (max 3 shipments a year without a Code, and it's a heavy process to get a code).

Glad you found the schematic, etc.
Having looked over it again, there isn't much I'd change, except you might want to put antiparallel LEDs (i.e. clipping style) in parallel with the LFO depth control. This will stop the LFO clipping against the rails and might make it even quieter. Will also give you a cleaner square wave LFO at higher depth settings.

As always, I also suggest you breadboard it before heating up the soldering iron.

p.s. As someone else who grew up in the antipodes, I can empathise with your issues regarding shipping, etc.

[Joncaster]

Glad you found the schematic, etc.
Having looked over it again, there isn't much I'd change, except you might want to put antiparallel LEDs (i.e. clipping style) in parallel with the LFO depth control. This will stop the LFO clipping against the rails and might make it even quieter. Will also give you a cleaner square wave LFO at higher depth settings.

As always, I also suggest you breadboard it before heating up the soldering iron.

p.s. As someone else who grew up in the antipodes, I can empathise with your issues regarding shipping, etc.

Thanks Sam!
Yeah i would definitely breadboard it first. I'll start getting it together soon.
Just checking: your latest schem is V1.3 (29/05/13), right?

I can also try that Tremolomatic-X from Stompology, but I can only find SOIC NE570's here, so that would need a SOIC/DIP adapter board (found one for about $1 here), and some patience, and possibly a smaller iron tip, my small chisel might be a bit clunky.

[samhay]

Yes, V1.3 seems to be the latest version.

[Joncaster]

In the meantime (ordering parts requires payday), I put a Heartthrob on the breadboard, to see if I could harmonic-ise it.

I just made two stages of the heartthrob, and did some crude Hi/Lo-pass inputs, and took either side of the BJT LFO modulator to each input.
Then I just tied each output via mixing resistors straight out.
I got somewhere at one point (it was actually sounding incredible for a second), and then it started sounding horrible...i think my little breadboard is possessed.

Tried a buffer input but haven't figured out the impedance relationship to the modulator yet, so that sounded loud and distorted and terrible.

I laid it out as a normal tremolo again, but still getting a little bit of distortion on louder chords, want to track that down first.
The preamp alone (LFO disconnected) sounds clean and fine.
Is that just the nature of BJT LFO modulators?

I'm wondering about slapping in a LED/LDR combo in place of the BJT, but at this point, I don't really know what i'm doing...so I'll have to see.

[bool]

A bjt-modulator will add a bit of grit - you need to scale your input signal to the "sweet spot" where grit sounds bloomy but not yet distracting.

Imho the good way of dealing with the signal routing would be to buffer the input; split to a LP and a HP; into modulators; and into the summing/booster stage.

Which is what you already did? Imho you now just need to properly scale the signal levels across the input; modulator; and booster stages.

[Joncaster]

A bjt-modulator will add a bit of grit - you need to scale your input signal to the "sweet spot" where grit sounds bloomy but not yet distracting.

Imho the good way of dealing with the signal routing would be to buffer the input; split to a LP and a HP; into modulators; and into the summing/booster stage.

Which is what you already did? Imho you now just need to properly scale the signal levels across the input; modulator; and booster stages.

Thanks Bool,
I'll add in a input buffer again, I think I know where i went wrong the first time.
I'm sitting at work reading up, taking notes haha.
In terms of summing, I'll tack on another stage, but for my testing I've just done the Univibe thing for now.

Need a bigger breadboard...again.

[Joncaster]

Edit: disregard

[Mark Hammer]

My wife and I went to see Joey Landreth last night.  It has awoken my interest in having a harmonic tremolo.  I like effects that make chordal work more interesting, and harmonic tremolo is certainly one of those; certainly in his hands.  He encored with the old Ry Cooder tune from Bop 'Til You Drop, "I Can't Win", in which his (Landreth's) use of harmonic tremolo figured heavily.  To quote Roger Daltrey:  "I want it, I want it, I want it".

[GGBB]

My wife and I went to see Joey Landreth last night.  It has awoken my interest in having a harmonic tremolo.  I like effects that make chordal work more interesting, and harmonic tremolo is certainly one of those; certainly in his hands.  He encored with the old Ry Cooder tune from Bop 'Til You Drop, "I Can't Win", in which his (Landreth's) use of harmonic tremolo figured heavily.  To quote Roger Daltrey:  "I want it, I want it, I want it".

Mark - for some reason I thought you had a Chase Bliss Gravitas no? I love the harmonic trem on mine. But even sweeter is the hybrid mode - part normal part harmonic tremolo. Not DIY of course.

[Mark Hammer]

Actually, I wasn't aware it did that.  Shame on me. 

[Joncaster]

Joey did that whole episode on harmonic Tremolo with That Pedal Show:
https://youtu.be/FDRHDy9GI-M
Was a cool episode.
I love the way he plays.

[Mark Hammer]

I kind of thought so, but didn't see a Gravitas on the pedalboard.  He had a small-cab Victory amp head that I thought I overheard him telling someone during the soundcheck had a special pre-Blackface tremolo in it.  I just figured it was that.

[Mark Hammer]

Here's a question for the more knowledgeable: does harmonic tremolo need to be reciprocal?  That is, does the volume rise in one half of the signal need to be complemented by a drop in the other, or is the effect still likely to be pleasing if the two paths are simply wobbling in unsynced fashion?

If there are any commercial units that do that, I have not knowingly heard them.

[ElectricDruid]

Here's a question for the more knowledgeable: does harmonic tremolo need to be reciprocal?  That is, does the volume rise in one half of the signal need to be complemented by a drop in the other, or is the effect still likely to be pleasing if the two paths are simply wobbling in unsynced fashion?

If there are any commercial units that do that, I have not knowingly heard them.

I'm not sure that's a question of *knowledge*. That sounds like more of a question of *taste*.

We should try it. Do we like it? There's your answer...

The non-reciprocal version is only one LFO more complicated, and probably saves an inverting op-amp anyway, so there's really not a lot in it. As firmware, you could include both options - "standard" opposite phase outputs to drive the harmonic trem, or a "unrelated LFOs" version.