Harbinger 1.5 power question

[atodovax]

Hi everyone. Does anyone know why the harbinger 1.5 uses 18volts for the signal path and 15 regulated for the lfo and not the way around? I wonder why the easyvibe uses the other way around. 18v for the lfo and 15v for the signal path. The harbinger sound super good but im wondering how different would the lfo behave at 18 instead of 15. Also, would the lfo behave worse if fed directly from the unregulated 18v from the charge pump?

[gordo]

I have little knowledge of these things but I believe you have to worry about the 18v bulb going POOF on you.  Those things, like most bulbs, are capable of stuff beyond their ratings but given that it's on all the time, and modulated at that, it makes sense to reign it back in a bit.

I see chats all the time about shutting it off when not needed but I think running it a bit cool makes more sense.  The wear and tear is at power up and pushing the limits.

[madbean]

This is just a mod I prefer for the Univibe. Some bulbs can actually run at 18v, but regulating the LFO guarantees it is always consistent through operation. Possibly it might lengthen the operational life of the bulb, too, but that's just me speculating.

Regulated voltage is less critical in the audio path of the Univibe which is why I chose that little bit of extra headroom you get from 18v vs 15v. Does it make a huge difference? Probably not. But, it certainly doesn't hurt either!

[atodovax]

This is just a mod I prefer for the Univibe. Some bulbs can actually run at 18v, but regulating the LFO guarantees it is always consistent through operation. Possibly it might lengthen the operational life of the bulb, too, but that's just me speculating.

Regulated voltage is less critical in the audio path of the Univibe which is why I chose that little bit of extra headroom you get from 18v vs 15v. Does it make a huge difference? Probably not. But, it certainly doesn't hurt either!

Thanks for replying! I actually love the Harbinger 1.5 and have built 3 of them already but i was wandering if maybe the LFO could benefit from the extra 3 volts, using it directly from the 18v rail. Im just not 100% sure if running both lines LFO and signal path from the same 18v would be transfered into weird noises in the singal path.. So maybe i could try using the 15v regulator for the singal path. What do you think? The Univibe has some little filtering for the singal path but that is, i think to, get the ripple off from the transformers output.. Maybe i could run both LFO and Singal from the lt1054[s output?

[atodovax]

I have little knowledge of these things but I believe you have to worry about the 18v bulb going POOF on you.  Those things, like most bulbs, are capable of stuff beyond their ratings but given that it's on all the time, and modulated at that, it makes sense to reign it back in a bit.

I see chats all the time about shutting it off when not needed but I think running it a bit cool makes more sense.  The wear and tear is at power up and pushing the limits.

You are right about that.. Maybe i could use a higher voltage bulb?

[madbean]

...i was wandering if maybe the LFO could benefit from the extra 3 volts, using it directly from the 18v rail.

In this case, no, there is no benefit. Remember that this entire section is a low frequency oscillator (it's completely below the audio spectrum of human hearing). It's particular voltage operation has nothing to do with the quality or tone of the audio output. However, there can be a definite effect on the "tone" of the Univibe depending on some parts used in the LFO, namely the LDRs employed (which are generally spec'd at 6.8MOhms or greater dark resistance for maximum depth of effect).

It's good to question these things and you should keep doing that. But in this case I don't believe you'll gain anything by changing the LFO circuit to operate at 18v.

[atodovax]

...i was wandering if maybe the LFO could benefit from the extra 3 volts, using it directly from the 18v rail.

In this case, no, there is no benefit. Remember that this entire section is a low frequency oscillator (it's completely below the audio spectrum of human hearing). It's particular voltage operation has nothing to do with the quality or tone of the audio output. However, there can be a definite effect on the "tone" of the Univibe depending on some parts used in the LFO, namely the LDRs employed (which are generally spec'd at 6.8MOhms or greater dark resistance for maximum depth of effect).

It's good to question these things and you should keep doing that. But in this case I don't believe you'll gain anything by changing the LFO circuit to operate at 18v.

Thanks . I didnt mean by any means to question the desing. I honestly love the harbinger 1.5! I was just curious on why the Easyvibe uses the regulated part the other way around. I have read that some Univibes had almost 24v sometimes on the LFo since it was hooked directly to the output of the transformer (even with the pedal working) and i was thinking  maybe that would make the oscilation somehow "better"? Hehe ... Who knows. I was just curious on why the Harbinger was using the power section like this. I built three of them and didnt even realize this until a couple of days ago. I alwasy though that the LFO was the part runing from "18v" from the charge pump

[madbean]

Thanks . I didnt mean by any means to question the desing. I honestly love the harbinger 1.5! I was just curious on why the Easyvibe uses the regulated part the other way around. I have read that some Univibes had almost 24v sometimes on the LFo since it was hooked directly to the output of the transformer (even with the pedal working) and i was thinking  maybe that would make the oscilation somehow "better"? Hehe ... Who knows. I was just curious on why the Harbinger was using the power section like this. I built three of them and didnt even realize this until a couple of days ago. I alwasy though that the LFO was the part runing from "18v" from the charge pump

You should question design choices!