help diagnosing - Fender stage 112 SE guitar amp

[phatt]

Yes I agree with Juan ,,those crunch circuits are chasing a different sound but as Peter B has found it's all rather lacking in ability to control the sound.
A lot of those amps are designed for a niche market, Often the clean channel is,,,, well er normal and often nothing special. (which can be a good thing if you know how to use pedals wisely,,, hint )

The hot channel is often geared towards one style of guitar sound and you need to be very much aware of this when purchasing gear.

The sales person might be able to make the amp sound like a metal freak at a rock concert but ask him to play Country or Jazz riffs and I bet it won't sound so good at all the other styles.

Now of course if all you ever do is get drunk on friday nights and slash power chords for a few hours with no real intention of ever wishing to learn how to play a broader spectrum of music styles then the Amp will be heaven. But as you mature in musical awareness you will look back on those amps as trashy and harsh and lacking in tonal spectrum.

Now as to tweaking the tone circuit,, Yes I will have a look but As  Mr Fahey has noted it's a matter of if you can cut the circuit.
If you have 3 thumbs and are heavy handed then messing with pcbs can often lead to a dead amplifier,, land fill. 

I'm not a big fan of hacking into circuits at least not until I've exhausted other external options. As I alluded too in earlier posting the Fender pro 1,000 was a dead end and in the end I by passed the whole preamp. He now uses the power amp and speaker as a final drive for a preamp I built for him.

You may have to first find the tracks then run shielded cable to a dedicated efx loop type idea for the external tone test otherwise it's all a guessing game and many parts will be resoldered many times which will eventually lead to broken traces,,often ends in tears

Give me time and I'll try and simulate the whole of that channel.
But meantime JMF might have a better option,, he has way more experience than lil old Me, I'm just the hobby geek here.  :lmao:
Phil.

[Peter Blair]

Well guys, I will admit that sounds somewhat intimidating. I wouldn't say I have three thumbs, but it is far from essential for me to alter the amp in the first place. Simply changing out a couple components . . . not so scary. Maybe I should just leave well enough alone. Personally, I have no interest in the "drive" channel. I simply thought it might be cool to see what could be accomplished. For now, Phatt, I'll just wait and see if you can get any results on the simulator, that seem like they may be worth pursuing.

Mr. Fahey, I think your idea is a good one, but I might be in a little over my head in it's execution (according to Phatt's description).

Thanks to you both for you help, and moral support too, I should mention. You have both provided encouragement for me to continue trying to learn. Dabbling in electronics is something I've been fascinated with all my life. I finally have the time to do it!

Thank you both again,
Pete

[phatt]

That tone is loading down the whole signal and little can be done,,
with my talent at least.   xP
So I'm sorry but likely no easy way around this one.

I've added a basic tried and true tone circuit in place of the original.
All dials in both cases are at 50%.

In both cases Green line is the input curve , Blue line is original output,
Yellow line is a basic guitar known to work ok tone circuit.

Note the 8dB improvement is signal energy on the yellow trace!! 8|

One option is to bypass the whole tone section completely which
will raise the signal up by 25dB at 1khZ. That's a big lift :dbtu:

That will either be fantastic or a shocking failure,,
Result depends on other factors, speakers and styles you want to play.

Adding that option to give you an idea of how rewire it.
if it's too harsh you may need to add a cap across U2B, also shown.

Be warned,,,If you dive in to a modification it's addictive,,
but it's a huge buzz when you have your first victory. <3)
Phil.