EH LPB-1 input and output caps question

[WholeLottaDimitri]

I really like the drive channel of my but I just want to get a little more saturation and vibe from a pedal. So I was looking into the LPB-1 to build myself.I've built a couple pedal is the last year but I don't completely understand the science behind it. My question is, is there a difference between these two versions? I see the input and output caps and some resistor values are different. So what kind of sound would each one give me?





What kind of sound does each version give me? I also love vintage sounding effects so which one would get me closer to the original vintage LPB-1?

[garcho]

They're almost identical. The difference is that the second, colorful schematic has component values that are more common than the first, black & white schematic. If you can find the 150N caps, 830K and 360R resistor, I'd go with the black & white one but I doubt it'd make much difference.

[anchovie]

There isn't really any "vintage mojo" in this as it's just a simple transistor booster - you put a signal in and it comes out louder. The influence on the sound will be what the amp sounds like with a larger signal going in!

[Kipper4]

If you wanted to experiment with input caps I'd try a 100n or  47n or 10n or 4.7n   and see what a differance each makes to the low/ mid freqauncies.
Once you change the input cap it wouldnt make that much of a differance if you didnt change the output cap from a 100nf because the input cap will have already done the work of toneshaping.
Is my understanding. Correct me if i'm wrong guys.

[garcho]

Also, 100N (.1u) and 47N (.05u) in parallel equals 147N equals good enough. And a 390R and a 4K7 in parallel equals 360R. And a 4M7 in parallel with a 1M = 830K.

[Kipper4]

Sorry Gary I edited my post so it was clearer.

[garcho]

It was clear, no worries. I was just referring to the differences in the two schematics, cheers!

[WholeLottaDimitri]

Thank you guys so much. I think I understand things a little better now. I'm going to try and find some of the odd values but if I can't, thank you gary for the components in parallel and series to make the right value

[WholeLottaDimitri]

Does anybody have any real life experience with a LPB-1 that they've made? If so, how does it sound pushing a dirty amp?

[duck_arse]

dimitri, do you have a breadboard? they are designed just for this sort of stuff. and you can turn a lpb1 into a sho just by inplugging diff parts.

[nocentelli]

Does anybody have any real life experience with a LPB-1 that they've made? If so, how does it sound pushing a dirty amp?

There isn't really any "vintage mojo" in this as it's just a simple transistor booster - you put a signal in and it comes out louder. The influence on the sound will be what the amp sounds like with a larger signal going in!

[Gus]

A few things
One a search at this forum for line power booster LPB etc should find a number of threads covering your questions

Two  This is not a "transparent boost" the input resistance of a tube amp is often about 1meg.  Also is has more distortion than a opamp circuit until the opamp clips.

The input resistance of this type circuit is both of the bias resistors in parallel and that resistance in parallel with the emitter resistor x the hfe of the transistor used.  So just looking at the schematic you know the input resistance is less than 100K

The input resistance interacts with the cable capacitance and the LRC circuit inside the passive guitar or bass.  This causes an EQ  when the resistance is low you lose the high end boost.

There are a number of boosters you can build, you need to define what you want from the booster to get a good answer.

[WholeLottaDimitri]

dimitri, do you have a breadboard? they are designed just for this sort of stuff. and you can turn a lpb1 into a sho just by inplugging diff parts.

I was actually really thinking about taking a simple electra distortion type schematic and messing around with it to try and figure out what I like best. But thats going to be a little later when i've got some free time off school.

[garcho]

+1 @ Gus

There are a number of boosters you can build, you need to define what you want from the booster to get a good answer.

To have Gus weigh in on your LPB-1 question is an honor, take my advice and take his advice.

[WholeLottaDimitri]

Sure! Well I have a fender hot rod deluxe and I really like the drive channel when its around 3-5. I've been reading a lot about boosters slamming the front end of a tube amp and the great results people get. I really just want to get some extra saturation from my amp or an extra sweetness out of it. Maybe the LPB-1 is the way to go, or should I be looking into a low gain overdrive?

[Gus]

One important point is the input resistance, this is part of the tone control you get with the volume setting of the guitar.

If you search for my posts you will see screenshots of sims with a sim of a guitar or bass and the cable.   I think I posted a sim of a LPB like circuit with a gain control.

What might good to do is build a LPB and then something like SHO and a treble booster and compare them.

[nocentelli]

Maybe the LPB-1 is the way to go, or should I be looking into a low gain overdrive?

If you like the break up of your amp when you play hard, the LPB-1 will give you some more of that. The inherent treble loss Gus talks about actually works out ok, since boosting your guitar's output will also boost any hiss and noise you've got in the signal chain. High input impedance boosters like the SHO can sometimes seem a bit bright for my amp+guitar, but many other people like the "glassy/hi-fi" boost it produces. Breadboards are superb tools for trying out simple circuits like this to see if they suit your rig: If you solder together a true bypass looper breakout box and wire it to your breadboard, it will save you time - you could literally layout this out and see how it sounds in less than five minutes.

If you think you might want a bit of extra dirt on top of the distortion produced by your amp, I would highly recommend trying out Paul Cochrane's Timmy in the medium- to long-term future when you've got the hang of breadboarding basics: It has bass, treble, gain and volume controls and can do clean/transparent boost, treble boost, boost with a bit of treble cut to smooth the harsh, plus any amount of extra dirt from none to nicely overdriven.

[WholeLottaDimitri]

I've heard so many great things about the timmy pedal! I've never tried it out before but all the videos I've seen just make the pedal seem so magical. I"m definitely going to try out breadboarding this year for sure. And I with have to try and build the TIMMY some time!

[Pojo]

Another to consider is the mini-booster:
http://www.muzique.com/amz/mini.htm

I pretty much keep mine turned on all the time for the purpose of hitting the tubes a bit harder. I find it benefits both the lead and clean channels of my amp just making everything 'better' to my ears. The cleans are richer and just on the verge of break up. And the lead channel gets nice and juicy with a bit more compression.

Also FWIW, I use an LPB style boost (my first active circuit build!) when I really want over the top gain on my lead channel...although I also added a big muff tone control modded to boost mids which suits my needs.

+ a million on the breadboard. Looking back I wish I had one since the beginning!

[Kipper4]

Bread boarding is definitely worth it.
I. Have a box of bits just for the breadboard. Stored in the box is a piece of foam with labelled componants sticking in it.
Great for experiments and to see if you like a circuit. Kind of a try before you buy thing.
I still get it wrong on the breadboard occasionally but it's just easy to debug too and super fast too.