Got a Blackheart Amp? Mod the hell out of it!

[vigilante397]

A couple amps ago I picked up a Blackheart Little Giant 5W head in a trade and I immediately fell in love with it. I promptly sold my previous rig (a Bedrock 621) and proceeded to mod the hell out of the Little Giant. This was still before my days of actually understanding amps, so I started with a kit from Mojotone to replace the PCB with an eyelet board and all the sweet axial "mojo" parts and also remove the 3W/5W switch in favor of a standby switch. I was thrilled with the results, but I used my limited knowledge to add a little more:

- I added an attenuator to the output so I could crank the gain and get a sweet overdrive at low volumes
- I added a line out jack so I could plug straight into a mixer for recording, monitoring live, running into a house mix, etc.
- I added a switchable "dummy load" so I could run the amp line out without a speaker attached without frying the OT

These are all pretty simple things that can be done on just about any amp, and they made the amp a very versatile practice and small gigging amp. But it wasn't big enough (or "boutique enough" as mentioned in a thread I posted a while back) so I sold it and put the money toward my Ceriatone (Matchless) Lightning and have never been happier.

But a couple days ago someone traded a Blackheart Little Giant combo into the music store I work at and we got a killer deal so I was able to pick it up from the store for $82. Exact same circuit as the head, same solid construction, but now adding a 12" Eminence 75W speaker. At $82 it was hard for me to say no, so I didn't I took it home and proceeded to mod it, the difference being that this time I actually know what I'm doing

So if you don't have one of these amps and don't want one you can stop reading now, but if you have one (or want one) then you may want to read through what I've done to mine and consider trying some of these yourself.

- First, since I wasn't planning on swapping out the board again (the stock board is very robust, thick traces, fairly roomy, easy to mod) I decided to detach the transformer leads, twist them together (esp. heater and HV leads) and trim the extra off. Makes the inside cleaner and also reduces noise.

- Next, I completely re-voiced the EQ. The stock EQ is a little on the bright side, so I wanted something a little more usable. I swapped C2 for a silver mica 250pF, C3 for a Vishay (Mallory 150s are cheaper, but I had axial Vishays lying around) 100nF, C4 for a Vishay 47nF, and R5 for a 33K. This gave me a little more gain, shifted the mids, and gave me more low-mids.

- Swapped R3 for a 750R. Warmed up the gain a little in the preamp.

- Swapped R9 for a 250K log pot, effectively working as my master volume. It works reasonably well, but you still lose too much gain that way so the drive isn't as sweet. I would probably recommend an attenuator instead of this mod.

- Disconnected the 5W/3W switch and put the master volume in its place; Jumpered the PT Screen pads so it's stuck on 5W; disconnected the PT's HV center tap from the board and ran it to a switch for standby. Used a Carlington Off/Standby/On switch so I can have it all on one switch and can leave the aforementioned hole open for the master volume pot.

I know these amps have been out of production for a while now so you can't run out and buy one new, but I hope this helps anyone that has one laying around and wants something a little different out of it. Also, with how much time I've spent pouring over this amp and its schematics, I can (hesitantly) volunteer to answer any additional questions about it if there are any.

[Renegadrian]

I am an happy owner of a LG head and cab - I dind't like the tone voicings, also it's quite awkard to see a Marshall Tone stack in a Fender inspired pre, so I just converted to Fender typical specs.

c2 250p
c3 100n
c4 47n
vr4 (bass) A250k
vr3 (middle) B10k (pins 3 and 2 connected together)
r6 removed and jumpered

that makes me quite happy. also tried a master volume mod (1mA pot between c6 and r10 with r9 paralleling the pot) - it cuts the gain and didn't find that so useful.

I also traded my work (populating an amp pcb) for a Killer Ant. stock is very rock amp, it spots a typical marshall style tone stack with fixed resistors instead of pots. I am trying some mods on it, the standard Marshall TS isn't my cup of tea, so I want to try other solutions. Fender TS gives too much bass. Gonna try the James!!!
In the KA, r13 and r14 set the output volume, just remove them and put a regular 1mA volume pot.

[vigilante397]

The James (Baxandall) is my favorite EQ and I use it on all my original designs

I haven't tried the killer ant, but I've heard good things about it. They never seem to come up on eBay or Reverb, so I guess everyone that has one likes it