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Old 8th November 2010, 01:07 PM   #1
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Default Modding a Fender Frontman 15G?

Hello, guys. I have a Frontman 15G but it isn't the best amp you could imagine.. it has no reverb.. the guitar tone is a bit odd and the amp has lots of noise and thermal hiss. I have just opened the enclosure and I saw that the PCB has empty spaces with missing parts and it says 'for reverb models only' .. which makes me think that the PCB for the reverb model (15R) and the non reverb model (15G) is the same.. So maybe i could just add the missing parts.. but I can't find a schematic for the R-version.. could someone help me, please?
Another thing.. about the hiss - the solution is to lower the values of all resistors which comprise dividers and filters (for the filters if i lower the resistor's value n times, i have to raise the capacitor's value n times to keep the same RC constant and therefore frequency response), right? Do you think that all that can be done and is worth it?
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Old 8th November 2010, 03:12 PM   #2
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Assuming it's the exact same board, and you can identify (and obtain) all the parts, then you should be able to add the reverb - but it all depends if you can find what they are, and obtain them (specifically the actual reverb unit - depending what it is).

I must admit I'm dubious about reducing noise and hiss by altering the values, for a start I would identify where it's coming from.
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Old 8th November 2010, 04:03 PM   #3
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Here is the schematic:- http://support.fender.com/schematics...ematic_68F.pdf

There are multiple copies of the schematic if you just google Frontman 15G. I haven't heard this amp. but I'd agree with Nigel, if there's a lot of noise and hiss it's probably because of a fault. OK, it's solid state, which isn't a big recommend, but Fender equipment is mostly pretty good. So don't go messing with the filters, just fix it before you attempt any mods.

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Old 8th November 2010, 06:01 PM   #4
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wakibaki, your schematic can easily be found on the Net, but if you have a close look, you'll notice that it doesn't contain the actual reverb section and the pcb layout has a blank white spot exactly where the reverb components should be. Thanks a lot anyway. I'm not talking about lots of hiss and hum.. with the guitar plugged it's hardly audible, but it is pronounced with the instrument unplugged, when the input is shorted to ground automatically, which eliminates ground hum as an option.. it can only be thermal hiss, I suppose. However, I'm going to add the reverb (or at least see if I can) first and then experiment a bit with the filters and the hiss.
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Old 8th November 2010, 06:50 PM   #5
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Quote:
Originally Posted by ribolovec2 View Post
wakibaki, your schematic can easily be found on the Net, but if you have a close look, you'll notice that it doesn't contain the actual reverb section and the pcb layout has a blank white spot exactly where the reverb components should be. Thanks a lot anyway. I'm not talking about lots of hiss and hum.. with the guitar plugged it's hardly audible, but it is pronounced with the instrument unplugged, when the input is shorted to ground automatically, which eliminates ground hum as an option.. it can only be thermal hiss, I suppose. However, I'm going to add the reverb (or at least see if I can) first and then experiment a bit with the filters and the hiss.
If it's quiet with the guitar plugged in, but hisses when it's not, then it sounds like the socket isn't shorting out correctly. You would expect any guitar amp to be noisey with an open input (which is why the jack socket is supposed to short out).

The overdrive channel is also likely to be noisely regardless, that's a consequence of high gain and clipping.
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Old 9th November 2010, 01:14 AM   #6
Enzo is offline Enzo  United States
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The Frontman 15R is the version with reverb. Also FM15R in some variants.

Yep, you can just install those extra parts and a reverb assembly with cables.
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Old 8th November 2013, 06:29 PM   #7
shanx is offline shanx  Canada
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For curiosity sake I tried a 25R out at a music store, and it had much the same issues as the 15G/R. Entry level practice amp with a low price tag so it wasn't really surprising. That was the reason I revisited this thread, because I guess there maybe a few people could be interested discussing possible mods and/or upgrading these things.
I don't know if the OP ever did the reverb add-on and filtering mods or if the project was abandoned and the amp is sitting in a dark corner somewhere...
If there is some interest maybe I should start a new thread?
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Old 9th November 2013, 04:21 AM   #8
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I have played through several of these lower end solid-state fenders, and a speaker upgrade in ANY of them can do a major improvement. I have seen success with celestions, vintage organ speakers, or some crazy enough to use alnico weber speakers. The stock speakers are often bargain-bin trash, IMHO.
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Old 9th November 2013, 09:23 AM   #9
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Quote:
Hello, guys. I have a Frontman 15G but it isn't the best amp you could imagine...
Possible suggestion : why not remove all the solid-state, keep the chassis, and built a Champ inside ?

A+!
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Old 9th November 2013, 12:31 PM   #10
shanx is offline shanx  Canada
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Yes I agree that a speaker upgrade would be major tone improvement. Even adding an external speaker jack would be a simple way to make it flexible and try larger speaker, or make it an amp ''head' as I saw some guys doing (which ruins the combo portability )
The thought crossed my mind about the tube champ, but looking at the chassis of this (just a bent sheet of thin steel) I think I would reserve all that good tube stuff for a proper chassis and tweed cabinet!!
The 25R has a very small reverb assembly inside the chassis. The reverb is a problem: it gets really muddy at higher depth settings (over 2 or 3) and maybe a combination of the feedback circuit and lack of a proper 'verb tank.
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