Lovetone Doppelganger

[Joep]

Hi All,

I was looking into a phaser project, and I was getting some inspiration from the Lovetone Doppelganger

Does anybody know if this is an OTA, fet or opto based phaser?

What does the colour knob do?

Thanks,

Joep

[ExpAnonColin]

I know there was a schematic out there somewheres, however ethical you consider it.

I'm not sure what phaser type it is, though.

-Colin

[EliGold]

I don't think there is a schematic on the net for this one.  I sure haven't seen one, and I have looked.  I would like to see it though.  My best guess would say it's FET based.

[Mark Hammer]

My best guess would say it is OTA-based.  Generally speaking, the best-sounding and most complex phasers have been either OTA or LDR-based.  This one sounds like it has OTAs, based on the modulation depth available at fast speeds.

[Joep]

Hi All,

Thanks for you answers.

Does anybody have an idea on what the "colour" knob does?

What is the typical LFO frequency range for a phaser?

Well I have 2 13600, wire them like the Small Stone/Ross Phaser, build myself a nice versatile LFO or two....that should get me going....

Bye,

Joep

[moosapotamus]

I always thought the Dopp was based on the Mutron Bi-Phase. In which case, it would be optical (LED/LDR).

~ Charlie

[Joep]

Hi Charlie,

The Bi-Phase has 12 stages, do you think the Dopp has the same amount of stages?

Thanks,

Joep

[Mark Hammer]

I took a look at the user reviews on HC and whle there is little technical information, it would seem like the following MAY be the case:

1) Not THAT many stages.  Having lots of stages, phasers start to sound more like flangers, and nobody made any comment to the effect that it was flanger-like.  I'm gonna go out on a limb here and suggest 8 stages max, but I may well be wrong.

2) Probably LDR-based.  I thought it was OTA at first and though it likely isn't FET-based, user comments about lack of hiss or distortion suggests LDRs.  Those puppies are dead quiet.  Although many LDRs are a little too sluggish to track faster LFO rates, they aren't *all* like that.

3) The "Spectrum" control is essentially your basic phaser-to-Univibe cap-swap.  Many comments about a Univibe sound, and a few snippets of it from the sound samples at the LT website.  A simple-enough thing to do, and though we may poo-poo it now and say "Is THAT all it is?", a few short years back it would have been revolutionary to have included this in a pedal, so hats off to Vlad.

Re: other queries...

The Colour control is probably regeneration/resonance amount.

The Blend control is likely dry/wet mix to go from 50/50 down to minimal phase shift intensity, rather than pan from all dry to all wet.  I'm guessing that from the presence of a Phase/Vibrato stompswitch.

Typical phaser LFO rates would go from somewhere around 10-12hz down to around 0.1hz or so.  Essentially a 100:1 sweep ratio, which is easy enough to get with your standard 2 op-amp LFO.

[moosapotamus]

Being a dual-phaser in a BIG box, I wouldn't be suprised if it has 12 stages (two six-stage phasers). But, I don't really know for sure.

Also, I could be wrong, but I do not think that the "Spectrum" setting has anything to do with changing the cap values in the filter sections. For one thing, a rotary switch like that is only going to be able to switch four caps, and I know there are more than four stages, total.

On the LT web site, one of the listed features is... True and Spectral (filtered) bypass modes. In Spectral bypass mode, I think the signal is routed through the (all-pass?) filters unmodulated, so the straight signal retains the same character (range of frequencies) as the effected signal. In True bypass mode, the bypassed (unfiltered) signal could have a very different character. So, the Spectral bypass setting can be used to keep the "uneffected" sound from sounding out of character from the effect sound.

Not sure if that makes sense. I've seen it explained much better. fwiw

~ Charlie

[Joep]

The bi-phase has two separate 6-stage phases that you can use for stereo or cascade, right?

It doesn't look like the Dopp has two stages, there is nothing on the Lovetone site about this. Although one of the HC reviewers mentions it is a bi-phase clone.

Anyway, enough stuff to think about, thanks all!

Bye,

Joep

[Mark Hammer]

I wouldn't assume that the size of the enclosure predicts the complexity of the circuit.  Lovetone has some standard-sized boxes and goes for the big knobs.  As the Meatball schem has shown us, a full-featured device doesn't have to be a morecomplex circuit, merely tap the full potential of what is there.  And as Zachary Vex has shown us, well, don't judge a book by its cast aluminum cover.

Charlie's point about the number of caps that would need to be switched, and the limits of rotary wafer switches has some merit.  On the other hand, it DOES have the capacity to sound Univibish.  Moreover, all attempts at Univibing phasers that most of us are familiar with have involved 4 stages and ONLY 4 stages.  So, uh, what happens when you have *more* than 4 stages to tinker with?

Are the requisite cap staggers only needed for 4 stages and everything can stay where it is?
Do you need additional staggered caps?
Do you need to have ONLY 4 stages for Univibe vibe?
Can you even GET a Univibe sound from more than 4 stages, and if so, how?

And here is the capper:  What if you stuck in a couple of fixed allpass stages with staggered caps in the *straight* path?  Remember it is the phase relationship between the two parallel paths that results in the notches.  We may be accustomed to fiddling with phase on only one of those paths but there is no reason why it has to be ONLY one.

[puretube]

I can switch 6 caps witha rotary....

more than 4 sounds more "naturallly", "evenly"
(=all, or at least more frequencies, or rather: a larger freq.-range involved, is shifted a more similar, even amount)....

read more about it in one of Dome`s patents from the `50s...

the "capper" in commercial projects is (until recently) : the cost...

ps: Mark: I`ll hopefully answer your PM after the weekend, when our
new CD is finished, and presentation-concert is over....



//www.ewerkband.de
//www.puretube.com