Trace Elliot Brat mod, need help

[gmaker]

greeting everyone

I'm new in this forum. Happy to find this forum as I'm a beginner and learning to mod my amp.

Currently I'm using Trace Elliot Brat 15R, that I really like. If possible, I need help to mod it so :
1. it has more presence,a bit brighter. CMIIW, I tried to change treble bleed cap on gain(C28) and volume control(C25) with no good result. I dont want to change the tonestack, as i like how it sound. just need more sparks. any possible mod to do this?
2. on boost mode (overdrive mode), the background hiss is very much audible when I turn volume pot over 12 o'clock. Grounding is ok. Considering this is 20 years old amp, is there any part i need to check/replace ?
3. I play it thru 2x12 cab. Is it possible to have more punch from it?  :cheesy:

many thanks,
Bob

[phatt]

Hi and Welcome :tu:


C27 (22nF) is across the audio input and as in nearly all audio circuits like this it kills off top end.

Try 2.2nF and test,, removing it completely will give you full bandwidth but likely it will squeal like a pig so don't go crazy. But be aware the hiss/fizz you mention will increase as the bandwidth is increased.  That hiss is a catch 22 and hard to solve if you want the massive distortion the younger players seem to love. xP  Reducing R36 or R39 may help ,,also increasing c22 up to ~330pF may help.
A balancing act may exist between C22 and C27  cut at one place take away some where else.
Like most guitar circuit designs with distortion you need to wipe off a fair bit of hi freq otherwise it causes all sorts of problems. Where and how to do that has many answers. 8|

Issue 3;
NO it's a small amp so if you want more power you need a bigger amp,, heck it's only 15watts so it will reach full power fast.  If the Amp sounds good I'd just slave another power brick from the Headphone output.
HIH,, Phil.

[gmaker]

Hi Phil

Thanks for your reply, appreciate it much.
I know, I play numbers of amp  :cheesy:. For 15watts, it is quite nice. Even a friend who use an old JTM45 like it.
Now, I can understand your input for mod 1 and 2. Would you explain how to slave the headphone ouput?

Thanks,
Bob

[phatt]

Well just looking again at schematic,, you would need a stereo plug into this amp and other end wired as mono.
The signal will be fairly Hot so don't plug into another higain guitar amp,, something with a line input with a level control would be ideal.

Anyway as you have it apart and obviously understand how to solder why not just break the signal path after VR5 which is likely labeled as master volume and mount a send return setup so you can then use the preamp section into any other rig but still have use of the internal speaker.
Phil.

[gmaker]

I get it. I thought you will show me how to cut the headphone output out from the circuit, so I can reserve some power juice  :cheesy:

I guess I'll try that send return mod. Thanks Phill, you rocks ! :dbtu: