More gain?

[LaGzo]

Hey there everyone, I own a solid state amp (Kustom quad100), I want more gain/distortion. It only sounds decent at higher volumes but at low volumes its really crappy for dirty sounds. Can I replace something like diodes/resistors to get more gain? I just need to know what to replace. I have decent enough soldering skills and to do this I think, I just don't know what to change. Enlighten me, please!

Theres a "gain" knob so it should control something, but what is that something? The pot is a 100k pot for the gain knob if that matters. and it says VR1 next to it on the board. Also a "boost" switch that boosts the gain a bit.

[syndromet]

It's hard to teel what do with the amp without a schematic. There is probably some clipping diodes in there, or a OP amp, that delivers the crunch, but you have to be carefull switching things in there.

I guess your safest bet would be a good distortion or booster in front of it. I'we tried that amp myself, and it sounds quite good. I bet it would sound lovely with a Dist+, tubescreamer or ROG Eighteen in front of it.

[joecool85]

Well, you could put a distortion in front of it (if you like a pretty nice "driving" overdrive, check out my 5th gear overdrive in the schematics section, its wicked easy to build) or you could run a booster in front like an LPB-1 or similar, that will push the amp into distortion.  As far as modding the amp itself for more gain, it should be easy, but only with the schematic for the amp. 

I did a quick google search for it with no luck, but if you search long enough with enough different terms it should be out there somewhere.  If not, you could take it apart and take a decent high res pic of it and we should be able to help you out with that.

[LaGzo]

Thanks for replying! I've tried looking for schematics before and I tried again this week and still have found nothing. I'll take pictures of the board when I get home today. The thing is I really don't want to use an effects pedal, I just want a straight into amp setup. If all fails then that will be my last resort. Thanks a bunch.

[sempri_fi]

see, told you these guys are good
and you never have to worry about getting flamed for not having a tube amp
or being a newbie for that matter

[joecool85]

Keep in mind you could build the pedal's circuit and put it into the amp's housing so that you would plug straight into your amp still.

[LaGzo]

Pictures will be in shortly.

http://smg.photobucket.com/albums/v726/LaGzo/Amp/

Just so theres no confusion the control layout is like this looking from the angle taken in the pictures.

Volume-High-Mid-Low-Gain-Guitar input-CD/Tape Input

[joecool85]

Thats wanting me to log in to view...I don't have a photobucket account.  There must be a way to hot link the photos.

[LaGzo]

Oh sorry, CLick to enlarge.

[teemuk]

I'm quite sure you can replace resistors to get more gain: Looks like your preamp has a decent number of operational amplifier gain stages. Find out the opamp type, google for it's datasheet (to find out its pin out) and trace the circuit board to find out which resistors are used to set gain in each stage. I guess that you want to raise the gain of the input stage slightly. This one should be pretty close to input jacks. Find out where the trace from the jack´s "tip" node eventually leads. I bet there´s plenty of ways to raise the gain right in (and before) the input gain stage but it´s just not worth it to start listing them here - especially without a proper schematic. Pointing a bright light at the solder side (while looking at the component side) should help a lot in tracing out the circuit.

The potentiometers... Well, the gain knob can either be located in the (gain stage's) feedback loop so that it controls the actual gain of the stage - or outside feedback loop, where it attenuates the signal before a gain stage. I guess its your job to find out... if you truly are experienced enough to mod an amp then finding out something like this should be one of the easiest parts in the whole process... Be careful with that board: If you lift a trace by applying too much heat it will be pretty difficult thing to fix.

[joecool85]

Be careful with that board: If you lift a trace by applying too much heat it will be pretty difficult thing to fix.

Yeah, thats a big issue.  I repaired a Fender 30w Bass amp and used too much heat and starting lifting the traces...what a mess.  I eventually fixed it by using some PCB trace in a tube, I forget what it's called.

[LaGzo]

Alright well I think I might toy around with it sometime soon. Does anyone know What value resistors usually give more gain? I'm not sure what values are in right now but Ill check later, had a long day and it's time to rest.

[joecool85]

Normally you would want to use a lower value resistor as most of the times they attenuate the signal.

[Christian G]

I emailed Kustom for you...they said they'll sell you a schematic for 15 bucks.  That could be well worth it if your heart is set on modding.

You could use that cash to build a pedal though too, that's what I'd do.

[joecool85]

I emailed Kustom for you...they said they'll sell you a schematic for 15 bucks.  That could be well worth it if your heart is set on modding.

You could use that cash to build a pedal though too, that's what I'd do.

I'd buy the schematic, but I like knowing how my amps are wired.