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Modding a Frontman 15

Started by Chorch Cluni, March 28, 2022, 09:32:55 PM

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Chorch Cluni

Hi all.
I'm a newcomer and after modding up a DOD FX50B I began playing the thing through some amps  and finally got to my little Fender Frontman 15 which we all know are not "quality" amps.
That being said, I won't sell it and got to think about modding it up:

1.- Adding a reverb tank. It has the circuit printed, so... could I just solder the missinf components and build a tank using some spring and transducers?.

2.- Removing the leds. I'm not sure about this one, but Youtube says that removing the clipping leds in a Vox Pathfinder 10 provides more volume a better gain tones...

3.- Adding an external speaker jack. It has one on the front panel but it disangages the internal speaker, which is plain crap, but could I run a cable from the stock speaker's + to the + of that jack and the same for the - connectors so I could drive both speakers in parallel?.




I'd start by number 3. Can that be done?.

Thanks in advance!.

Enzo

Yes, you can just fill in the missing stuff - follow the schematic - and have a reverb.  As to MAKING a reverb pan?  I sure wouldn't bother.

LEDs are just soldered in like any other part.  Remove one or both and see what you think.  You like it you leave it, you don't like it, put them back in.

Loudthud

A low cost amp such as this is probably not capable of driving an additional speaker. The power transformer and power output chip are carefully chosen for low cost. It may be possible to drive two speakers, but they would need to be twice the impedance of the stock speaker.

Tassieviking

That power chip (TDA2050) can drive a 4 ohm load, so you could theoretically run another 8 ohm speaker in parallel with the inbuilt speaker.
You will most probably find out the hard way that your power transformer will not be large enough, you can tell by the smoke pouring out of the amp.
If you did not melt the transformer you might blow some tracks up on the PCB if they are not large enough for the extra current if running 4 ohm loads.

But why would you even consider using the internal speaker which you said is crap, if you have a good sounding speaker cab you can plug it into ?
Why would you want to add the crap sound with a nice sound ?
(Unless you are using it to scare the crows of your veggie garden) ;)
 Just get a nice external speaker cab, or replace the internal one with something good.

I would get a nice speaker cab, one you would want to keep for your next great sounding amp, build your gear up with quality one step at a time.

The price you might spend to install the internal reverb might be better spent on a nice reverb pedal, especially if you can make it yourself.
There are no stupid questions.
There are only stupid mistakes.

Chorch Cluni

Quote from: Tassieviking on March 29, 2022, 04:54:36 AMwhy would you even consider using the internal speaker which you said is crap, if you have a good sounding speaker cab you can plug it into ?
Well... I have an unbranded 12 inch speaker in a monitor-like cab which, hooked up to the external out of the Frontman, sounds way too bassy. I was just wondering if I could add the harsh, fizzy and painful horror from the stock speaker, to get some more definition.

Quote from: Tassieviking on March 29, 2022, 04:54:36 AMJust get a nice external speaker cab, or replace the internal one with something good.

I would get a nice speaker cab, one you would want to keep for your next great sounding amp, build your gear up with quality one step at a time.
I have a 2x12 loaded with V-Type Celestions. That cab is mainly used with a Marshall 6100 head but the Frontman delivers a really amazing loud volumen on that cab. I'm not saying good, but loud.


Quote from: Loudthud on March 29, 2022, 01:38:06 AMA low cost amp such as this is probably not capable of driving an additional speaker.
That's something to think about.

Regarding the reverb issue, I could use some digital reverbs from a Digitech RP150, but it would be fun to have just this little combo sounding as best as possible, without buying new stuff.
It's a gift from my mum, so, you know... sentimental value, I guess.

Here's the best I got from it so far:

Jazz P Bass

If you can 'stuff' the unpopulated reverb circuit a proper reverb pan will cost about $25.00.

Tassieviking

#6
Quote from: Chorch Cluni on March 29, 2022, 06:39:13 PMIt's a gift from my mum, so, you know... sentimental value, I guess.

Well...a gift from mum changes things, mod it is.
Yes, add the reverb circuit to the PCB, while you are doing this you should add IC sockets to all the op amps.
Swapping op-amps will be easier, and sometimes this will change the tone or the distortion.
There are a lot of mod pages out there for the Frontman 15 if you google it.

The best mod is usually changing the speaker, also try using it with the back cover off, partly closed etc.
I have read that someone had great sucsess with a MOD speaker and 2 planks across the back, leaving a gap in the middle.
Is it possible to fit a larger speaker ? If you can go up a size it might be more efficient/higher dBA as well as nicer sounding.( you still need room for a reverb tank )
I don't know the amp at all, but if you can locate the caps in the filters maybe stick some sockets in so you can swap the caps till you find a better tone.
I mean low pass and high pass filters.
You could do the same with the resistors in the gain circuits, sockets and try till you are happy with the results.
Here is the service manual url: https://elektrotanya.com/fender_frontman-15_frontman-15r_sm.pdf/download.html
You cannot view this attachment.

The reverb tank might be harder to work out, Insulated input and earthed output, but the model number might be harder to work out exactly. The numbers people are floating around don't match what the DC resistance indicates exactly.
Fender Part No: 041397  Reverb Spring 1BB2E4A Reverb Pan
Someone measured the DC resistance as Input 28 ohms DC, and Output 229 ohms DC
That would indicate to me the input could be B or C, output B
If you mount the tank on the floor below the speaker go for a 8BB2C1B (8CB2C1B ?)Tank

A lot of people ask what mods they should do, not many answers as it depends on what you want yourself, nobody knows this.
If you ask specific questions like how to get more Bass, less treble etc. you are more likely to get more answers. People smarter than me know just what to do to to change high/low cut filters, increase/reduce gain and all that stuff.
Good luck and happy modding
There are no stupid questions.
There are only stupid mistakes.

Chorch Cluni

Opening tha cab does make it sound better, but it looks like there's no room to fit a larger speaker. An external one will be the way to go.
Thanks for the replies!.