Fender Frontman 25r clean channel problem...

[hongaku]

I recently got a brand new Frontman 25r with the intent of having something cheap I wouldn't be too worried about leaving at a practice space shared by multiple bands (I kept finding evidence that my Mesa was being "fiddled" with).
I replaced the stock junk speaker with an Eminence, and it improved the amp's sound and perceived loudness significantly. I was able to turn the amp's volume up quite a bit on both channels, and everything seemed fine. I've been playing it at the house for the last week with no issues and tonight was able to take it to the practice space. Everything was fine at first, but then the clean channel started cutting out intermittently; especially when I'd strike a single note or chord particularly aggressively and let it sustain. The problem also seemed to only occur when the volume was turned above 4.
The problem did not occur at all on the "drive" channel, so for the practice session I used that channel and just turned the gain down all the way.
This was an online order, so I'd have to replace the stock speaker and ship the thing back to get it repaired/replaced. It's such an inexpensive amp that I think I'd rather take a crack at trying to fix the problem myself before trying to send it back.
Does anyone have any ideas on what the problem might be?

Thanks,
Dave

[Enzo]

Well, first off, where are you? Bolting the original speaker in the amp is not really that big a job, y'know?

When you buy an amp locally, you are expected to return it to the store if it fails, and they will exchange it under warranty. Fender doesn't expect you to mail it back to Musicians Friend or wherever. You can present it to any authorized Fender repair shop along with a copy of your bill of sale. I am assuming you are in the USA at this point.

If you are a hundred miles from a service center or something, then contact the seller and ask for a return shipping "call tag." They will send you a shipping label billed to them. Usually it is a file in email you print out yourself and glue on the box. And if they balk, call Fender customer service and ask for help. Fender may send a call tag or even a replacement amp.

That is what your warranty is for.

[km6xz]

Since you voided the warranty by replacing the stock speaker you might as well fix it yourself. Since you have isolated the source of the problem to the clean signal path, you have reduced the search area a lot. The clean channel only has 1 IC amp (IC1b) that is used exclusively in clean mode. This does not sound like an IC, besides, its other half, IC1a is working fine as the preamp for both channels. I would first suspect a mechanical problem such as cracked solder joint or the control lines for electronic channel switching, even the foot switch itself that controls the Field Effect Transistors which do the actual path muting. Try slapping the top of the amp with the clean channel on, volume up and no notes being played to see if you are getting mechanical vibration creating the distortion. At high volumes the speaker would be supplying the "slap" that would modulate a cracked connection. Also tap the volume control in the same conditions, it could also cause what you describe.

[Enzo]

That didn't void the warranty. If he puts the old speaker back in it, no one will know it was out. As a warranty center, we are not going to care about that. There are no hidden or overt seals on the innards.

If you just want to fix it anyway, then go ahead, but I sure wouldn;t be cancelling the guy's warranty.

[hongaku]

Thanks for the feedback. I'm gonna go with Enzo on this one and just return the thing.
The bolts holding the stock speaker actually did have a greenish resin on them and around the shaft of the screw itself. Do you think I should try and replicate this before shipping it back?
Also, I'll have the option, assuming the return is accepted, of getting a direct replacement, choosing another product altogether, or simply getting the cost credited back to me.
I'm really not so sure I want to get a direct replacement of this amp model. It sounded decent for the purposes I wanted it for, but there is definitely a quality issue with these entry level solid state practice amps.
If I were to try a different small combo amp, what might some suggested alternatives be? I'm looking for somehing $200 or less and it can be solid state, tube, or hybrid; I really don't care as it is simply for leaving at the band practice space and I have a high quality tube amp for gig use.
I just want durability and usable tone.

[Enzo]

No, the green stuff is just dope to keep the screws from loosening. No one is going to bother to take the amp apart and inspect the screws anyway. And if the screws show signs of having been turned, ther is no way to tell if the speaker had been removed or if you had simply tightened up the screws that had come a little loose. The amp is going to wind up in a heap of dead amps, that's all.

And don;t worrry about opening the amp, that is the only way one can change a fuse after all.

You want more amp and sturdy? get an old Peavey solid state head from the late 1980s or early 90s. Their Bandits are very popular amps. Later ones are part of the "Transtube" series. They have transistor preamps configured to emulate tubes somewhat, and they sound pretty good.

[hongaku]

Thanks again for the advice. I'm really not familiar with solid state amps; the entire 18 years I've been playing it has been with tube amps. I'll look into the Peavey thing.