DIY or cheap onboard buffer opinions?

[Feral Feline]

https://www.premierguitar.com/news/introducing-black-ice-boost

An article just came out about a passive boost and overdrive/distortion.

Can someone explain to me how you can have a passive boost/overdrive?

You can't.

I looked into the Black Ice stuff (and 2or3 others like it) a decade or so ago.
It's a wee bit Snake-Oily to call a passive circuit a boost.

... AND
I just scrolled down and CyberCow has already debunked it in a way far better than I ever could. As he mentioned, it's just a few small components.

I don't think it involves a transformer. Well, at least the original Black Ice didn't (FAIK), but Black Ice company seems to have expanded its product line so maybe a transformer is in one of the products.



For anyone interested in something similar to a Black Ice device I recommend the openly transparent and clear Mojo Maestro by Ethan Winer.
I'm not saying the Winer-circuit is transparent itself, but rather that Winer presents information about it in an openly transparent honest way — no snake-oil.

Link to the Mojo Maestro article.
The PDF of Winer's MM article.
MM discussion on Mr Winer's forum.

DIYRe's take on Winer's MM: https://www.diyrecordingequipment.com/products/mojo-maestro-passive-clipping-colour




It's meant to be a stereo-circuit, but as you can see it extrapolates to a solitary channel easily enough:










Joe Gore's exploration of the Black Ice is here, as well as his own take on a passive-clipping method; and a Black Ice demo vid:

Here's yet another passive-clipping DIY article:

Passive Guitar Overdrive (Black Ice)

Passive Guitar Overdrive (Black Ice): A friend of mine brought to my attention a passive guitar effect, called "Black Ice" which takes the place of the capacitor (or wired with the capacitor) on the tone knob, and when used, gives the guiatr's sound a "crunch" similar to an overdrive. H…

www.instructables.com

If you dig around a bit, there are articles about people modding an instrument cable to have properties such as the Mojo-Maestro/Black Ice.
Nowadays, with SMD bits available, it's even easier to secret a passive-clipping device into a cable, let alone the huge space (relative to a cable and SMD parts) inside a guitar cavity.



Sorry for the digression, back to buffers and speaking of SMD, I quite like ELS's buffer-on-a-jack:

MICRO BUFFER – Effects Layouts

PedalPCB's buffers are on sale right now:

Simple JFET Buffer - PedalPCB.com

JFET Buffer

www.pedalpcb.com

Simple JFET Buffer (SMD) - PedalPCB.com

JFET Buffer

www.pedalpcb.com

and space permitting (if it suits your needs), a bypass buffer:

C-Buffer - PedalPCB.com

Compare to Cornish Buffer

www.pedalpcb.com

 

[Passinwind]

Waaait, I have to get to building a proper batch. I've only finished one so far. Should be a few days. I still have to work out what I should charge for it. The closest thing I found to compare with is an EMG part (PA2). I'm planning to beat their price, that's for sure. As for comparative performance and features, I'm really not worried.

PA2

The PA2 is a boost preamp you can mount to your guitar and turn on/off via on a minitoggle switch. It's the perfect solution if you want to increase your instrument's overall volume for solos or push an amp on the edge of breakup into overdrive. It has a trim pot so you can preset the amount of...

www.emgpickups.com

P.S. I'd really, really like to know how they came up with their -130dBV input referred noise spec. That's just massively not achievable with their TL062.

Just curious: what's the best noise floor you've measured for an actual electric guitar or bass?

 

[JTEX]

I couldn't recall, so you just made me plug my guitar into the AP again The lowest noise I could get out of the output jack, with volume and tone full up, is around -107dBu. That's after I rotated the guitar around to minimize EMI and muted the strings as best as I could. This was the bridge pickup (about 16kohm). Its theoretical noise floor is -111dBu, maybe only really achievable if enclosed in a mu metal cage, so it wasn't too far off. The peaks, when slamming it as hard as I could, were in the region of +5 to even as much as +10dBu on rare occasions. So yeah, a guitar has a lot of dynamic range.

The mid pickup should have been quieter (noiseless single, about 10k resistance), but in practice it did not reject EMI as well as the bridge humbucker, so I could only get about -105dBu out of it.

 

[Cybercow]

That's pretty much all that's needed for a simple buffer. It probably draws a good milliamp or 2 though.

Thinking your estimation of an mA or 2 current draw on the dead-bug buffer I showed was high, I took out my ammeters and measured the current draw. The One-Spot Ammeter wouldn't even measure below 1mA, so I brought my Hantek DMM to bear - measuring in at ~220µA . . . .

 

[JTEX]

I just did some SPICE simulations to better explain what I'm hearing with buffer versus no buffer. It's more or less what you see in this graph. The resonant peak's amplitude and frequency will of course vary from pickup to pickup, but the general idea is the same. The buffer, by decoupling the pickup from any other loads (pots, cable etc), can allow the resonant peak to rise to a significantly higher amplitude (and also frequency) than in a passive setup. The frequency of the peak can be tuned down by adding some capacitance across the pickup if desired. The peak amplitude can be controlled, from huge down to no peak at all, by varying the resistive load on the pickup (which is the buffer's input impedance).