A bunch of Bajaman preamps from FSB

[Blackboarcult]

Some time ago I posted a request for the Baja SLO to be veroed.
I have been using DIYLC a lot since then and I've been able to lay out some of the schematics to my taste.
So here's a bunch of them, I intend to post the AFD, JVM, Friedman and Engl anytime soon - as soon as I get my TL062 and 1uF cap stocks replenished, as a matter of fact
Designed for use with 5mm pitch terminal blocks, as usual.

all three verified, but won't post it on Verified Layouts until at least one other build is successful just in case.
Not very happy about the VH4 one, as it has a very tame gain and does not like to be pushed with overdrives (becomes muddy and fizzy at the same time), but as for the SLO and UBS, damn, they are awesome! perfect to run into a clean channel and upstream from a stack of ODs, boosters or compressors.

Cheers!

/ZVDW

Edit 09/04/19: corrected 47n cap spacing on output of IC2 in Baja VH4 layout.







P.S. you can find all these on the Ready-To-Build Effects subforum on FSB, should you need schem or mods.

[Sensei Tim]

Nice job!

How do you find the Baja SLO compared to the jfet based one in the blog here (modern SLO)?

[Blackboarcult]

Thanks Tim!

I haven't tried the Modern SLO, but I did breadboard your X88R a couple months ago.
While it sounded awesome, I ended up tweaking here and there (miller caps from gate to ground, BAT48 from gate to source) and it ended up very similar to JokerX's Blacker Forest, at least in blueprint

Baja's SLO has less gain, feels less like a real tube preamp, but on the other hand, the response is rich, full and "controlled": doesn't hiss, barely noisy, and is nicely balanced. Plus you don't have to worry about selecting J201s, set the g**damn trimmers, run it at 24V, etc.

It takes boosts pretty well (at least my diy-ed Rothwell love squeeze, TS9 and Cornish SS-2) and with a 6 or 7 band eq before or after it you can tweak to taste. If you put a mild chorus after it you can nail some nice 80's Judas Priest tones

I'll probably end up using it in front of a clean amp to set the dirty "base tone".

Cheers!

[Blackboarcult]

Adding Baja's take on the Friedman BE-100.
Nice sounding one too, I have yet to test it at full volume on a proper amp.
Laid out for a single TL064 'cos that's all I had in stock

Edit 09/04/19: amended wrong cap value at output of Gain 2 (4n7 on schematic)

[glasspak73]

Could you do the EVH5150 that Baja posted? Sorry this schematic is so huge I'm not sure how to make it any smaller for posting.

[Blackboarcult]

Hey mate, yup, this one's on my "pending" list along with the MDR and JVM.
Haven't started working on it yet cause it's 3 damn TL072s, and I hate doing layouts with that much opamps, it gets messy and crowded with jumpers waaay too quick

Do you need the tonestack? I'm pretty happy building those without it, plus I'm not really into Baja's way of replicating them (at least the Plexi and the Engl TS were not very versatile).

[glasspak73]

Thank you for all of these you have done.I don't need the tone stack I could build that on a separate board if i ever wanted to try it.I'll keep checking back here to see if ya got one done,I always check these pages about 20 times a day now lol thanks again for all you do its awesome work and very very much appreciated.

[Blackboarcult]

Okay, having a sleepless night here enduring the spanish climate & heatwave, I decided to lay it out.
After four Nazareth albums, five gintonics and three snus portions, here's the result

Definitely not my best, there's a sloped resistor and the highest abomination of all, a flying lead in the middle of the board (could not fix this mistake without completely trashing two hours of work). If I have to be dragged before the Grand Supreme Solder Court for this, and have NOS germanium tranny legs inserted into my fingernails to atone my sins, so be it

Well, mildly-drunk-jokes apart, it's yet unverified. I have double checked it and I'll give it a go tomorrow if I feel like soldering, meanwhile, take it with a pinch of salt.

[Greedy_Fly]

Hi.... How much gain in this pedal (Baja UBS Overdrive)???

[Blackboarcult]

Less than on the original amp for sure... but nothing that a good overdrive can't remedy. I'm currently using that one for rhythm on Heavy Metal tunes with a little help from a TS9, great mid-focused tone with lots of juice and meat.

[Greedy_Fly]

How can I increase the gain on this circuit??? ... Add the SHO in front of this circuit? 🤔🤔🤔

[Blackboarcult]

Any booster/OD would suffice, it's a matter of taste. I'd recommend something like a Maxon OD820 or similar neuter-tone OD if you like your guitar-preamp tone.
I guess a SHO or LPB in front would be the way to go if you want to box it altogether, though. The thing is, if you tweak the circuit itself to wield more gain you might lose the original freq response.
I suggest breadboarding and experimenting to see what you like best

[Blackboarcult]

Adding a verified layout: Baja MDR, Based on the Mesa Dual Rectifier high gain channel (without the tonestack as opposed to the one on the main site)
And it's a really awesome sounding circuit! I tested it with a D-tuned Ibanez and hell, some mean tones there without needing an OD in front.

[Sensei Tim]

how do you like this compared to the Dr. Boogie?

[Blackboarcult]

I've never built the Dr Boogie, despite it being a staple of DIY pedals
This one I built for a friend, as I've never really liked Mesa amps or Mesa-flavored pedals, but I must say it sounds damn good for modern heavy tones, death/thrash and even for black. Sorry I can't compare to other similar sounding builds...

[Greedy_Fly]

Hi, All!
Substitute for BC547B in these schematics?????

[Blackboarcult]

BC549B, BC549C, BC184 have roughly the same specs, but haven't tried them. You could also try 2N3904 and 2N5087/88 minding the pinout.