Kustom KG100 Hfx mods!

The Kustom kg100hfx guitar amp is a solid state head that puts out 100W of pure analog power (no class-D or switching systems here) and it costs only 180Euro! I bought the previous generation (2010) KG100Hfx model and I modified it! The new model is basically the same amp with a different front-side tolex colour and different plastic knobs.
 The control panel itself is pretty simple and basic with two channels, a common EQ setting, high and low inputs for passive/active pickups respectively and 3 effects (2 can be used simultaneously).
 Over to the back panel, there is a speaker output capable of driving 4 to 16 Ohm speaker cabs and a classic serial FX-loop (only send and return jacks).
 I opened up the amp and found a big transformer for the power supply which is good and rare for this price nowadays. Transformers can last forever while switching power supplies in most solid state and digital amps have all kinds of problems after a few years of regular use. The PCB design and the quality of the components is decent.
 This is a highly serviceable amplifier with large electronic components. Maybe it's the last amp head of its kind since most companies produce low cost and low quality pcbs with switching power supplies, digitally controlled channels and settings plus class-D output amplifier modules (similar modules can be found on eBay for 7$...).
 There is no footswitch included but Thomann is selling a compatible two-button one for 12.90Euros:
www.thomann.de/gr/lead_foot_fs2.htm?partner_id=73786

So, how does it sound?
Ok, all this build quality stuff is good, but how does it perform? I would say that it sounds decent.   There is no huge tonal variety but it's like having a simple super-clean amp and a Boss distortion pedal that you can turn on and off to get some dirty sounds.
 The basic clean channel has plenty of punch and bass and it sound good with a strat/tele guitar. A les paul guitar could sound a bit bassy even with the bass eq turned down.
 The overdrive channel on the other hand has less of low end punch and more treble. The amount of gain is Ok for blues, rock and even hard rock stuff but you are going to need a booster pedal for metal stuff, shredding or simply riffing with low output pickups. That's why I modified the amp!
 The effects sound subtle and don't make a huge difference in tone which is why there is an added FX loop. You can turn the effects wet signal up a bit by modifying the amp as I will explain in a moment.

The mods!
At first, I wanted to get a bit more gain and less muddiness out of my humbucker equipped guitars. A treble booster pedal can solve this issue but there is a more permanent fix. This one was easy as I simply cut the legs of the R55 (220K) input resistor and removed it. The amp gained a bit of treble for the clean channel and a hint of gain boost for the OD channel.
The rest of the mods are pretty easy and reversible! You can do all of them without even removing the pcb. All I did was to bypass a few resistors with other resistor/capacitors simply by soldering their legs across the legs of the old components. I did not remove any old components (except R55 as mentioned previously).
Here are the mods for extra overdrive gain and a wet signal boost for the on-board effects:
1)Bypass R32 with a 1Mohm (MegaOhm) 1/4W resistor
2)Bypass R22 with a 22nF (nanoFarad), 63Vdc film capacitor
3)Bypass R27 with a 10kOhm 1/4W resistor
4)Bypass R8 with a 4,7kOhm 1/4W resistor

The amp sounds decent now and I can turn the reverb up quite a bit. There is also plenty of OD gain available on tap. I use the 1st input (Hi) mostly and I only operate the chorus effect on the clean channel. I tried a few overdrive and distortion pedals in front of the amp. The clean channel sounds good with most effects, even metal distortion ones. It's not performing like a clean tube amp but it's closer than most modern solid state amps of this price range.
The Kustom amps are nice underrated amps that can produce some interesting sounds when paired with a good cab and a couple of simple effect pedals.

Here are some photos:

Cheers,
Thanos