BJFE Blueberry Bass Overdrive

[traktop]

I´m digging this thing. Spent the whole weekend recording DI bass lines, (I´m not the bass player...) for some tracks we got and it sounds round and full without any kind of shrillness or "plastic" sound that DI recordings use to produce.
Did anyone notice something strange on the tone knob? I mean, my build seems to loose drive when going to the center. As you move it to the right, highs and gritt start to appear. When moving to the left it gets really bassier but again grittier and grittier. Is just at the center that seems to be on the middle of nowhere. Nothing extreme to worry about since I just love that tone pot at about 2 o´clock.
I checked pots and vero and everything seems right.

[rocket88]

Correct, that's normal. It's because the tone knob really sweeps between the 2 sets of clipping diodes. So in the middle you're going be have roughly half going to the Si and half going to the LEDs. Due to the difference in forward voltage you get different clipping characteristics. The LEDs have more headroom thereby effecting the highs, and the Si have less headroom clipping more lowend. Btw, glad you dig it. For me it's one of my favorites.

[Silver Blues]

Seconded on that being correct. The whole tone network is actually a kind of feedback system as well.

[Sensei Tim]

Rocket,

I built this for a local bassist and he asked me if there was any way to get a bit more output/gain from this.

I've been trying to use http://www.daycounter.com/Calculators/Op-Amp/Op-Amp-Voltage-Calculator.phtml to figure out what resistors to tweak to get a bit more output but i'm having trouble identifying the proper resistors.

[rocket88]

i'm thinking a few things you could try. to increase the overall output i think if you just up the volume pot to like 100k you should get more output. to increase the gain if you up the drive pot to like a 500k i think will up the gain, you can also up the 3k resistor in line with it, maybe to like a 5k or 4.7k.
 
remember that the op amp goes into the jfet buffer.

[Sensei Tim]

Another question.  Is this pedal supposed to have greater than unity gain when the level knob is maxed?

[rocket88]

mine does, but the amount of total output is dependent on the gain pot. ie if the gain pot is low, the level pot is higher to compensate. also the position of the "tone" pot will have an effect since it's just controlling how much signal is going between 2 different sets of clipping diodes.

[kragg]

Hello, Rocket88 suggested me to take a look at this pedal...

I would have two questions, prior to building it :
- Is there any differences between the two layouts posted on the first page (Yeray's and Rocket88's), or are they similar ?
- It seems that BF244A are hard to find nowadays : is it mandatory to get them, or is there any easier to find, dropin replacement ?

Thank you !

[Silver Blues]

In terms of functionality, the two layouts should be the same. I built Rocket's layout and it's really very nice.

As far as the JFETs go, try a couple. The Bearfoot version uses a 2N5952 if I remember correctly. It sounds different, but the component values in the filters are slightly different, too. Is Tayda out of the BF244As? I got mine from there and it was totally fine.

[kragg]

Thank you, Silver Blues

[Zanius]

Hey, thanks for the layout, just wanted to confirm that using a A500K gives a good amount of extra gain, doesn't sound very good after some point but still useable to have if the occasion for some extra dirt rises. Definately better opposed to the 250K since the A370K the schem calls for is unoptainable. :)


Also used a A50K for the volume pot beacause with the B50 i found myself having to set it very low to get unity and that just bugs me.

[Sensei Tim]

you could always use a 500k pot and put a 1M5 resistor across pins 1 and 3 to get a 370k pot.  the taper might not be exactly the same but at least it'll give you usable gain across the span of the pot.

[Alamondm]

The Bearfoot layout calls for 1N4007 . I currently don’t have any. Would there be much of a difference using 1N4001 in the Bearfoot layout. I have built the BJFE version and like it but want to build the Bearfoot to compare.

[rocket88]

It will be close enough. TBH I’ve built both, and the Bearfoot isn’t worthy of the name. The BJFE blows it out of the water.

[j-pee]

there's a NEW version, with 2 transistors, or more precisely, with an added preamplification stage...
and green LEDs instead of red... (according to the higher signal level) (or was this, perhaps, the original version?)

anyhow, it's here, at dirtboxlayouts:
https://dirtboxlayouts.blogspot.com/2021/05/mad-professor-blueberry-bass-overdrive.html

this would make the comparison / competition / evolution "complete"...

...................
PS:
I'm eager to build the preamped-one, the GREEN version (?), and try both, finally :) (I've built this, only I haven't tried it... cause I like, it seems, to prolong the stage when it's finished but no cables are wired in yet :))
only I don't have 2N5457s, just "BF244As" :)
so I need a modified new layout, for DGS transistor pinout, which I have asked for @ the dirtboxlayouts' post

[Bolsyo]

This thread is for the original BJFE Blueberry, which seems to be the most popular according to Talkbass.

That dirtboxlayout is for the Mad Professor Blueberry, which seems to be the least popular version of them all from what I've read on Talkbass, also behind Bearfoot's version.
There is also a layout for it here: http://tagboardeffects.blogspot.com/2012/06/mad-professor-blueberry.html

[Silver Blues]

The MP Blueberry seems to sound way better with a Kreuzer Submarine in front of it, a la JohnK. Leads me to wonder if it wouldn't be nice to put together a version that replaces the first gain stage with the entire Submarine circuit...

[j-pee]

thank you very much, Bolsyo,

talkbass is a good point of reference :)

and thanks, Silver Blues, for the Submarine idea!