Fender Frontman 25R

[xXBazookaJoeXx]

Hey guys! New to the forum! Glad to be here! 8| I'll preface this with saying that I have dabbled with tube amp modding and have actually done a few mods to my 6505+ to get a better sounding clean channel. Plus a few EQ tweaks on the lead channel to cut more of the higher mids and less of the low mids. So here's my problem. I have a Fender Frontman 25R and I love the gain structure of this amp and I can get an overall good tone out of it but the low end is lacking extremely. I was looking at the schematic for it and I don't really understand it's EQ network! I'm used to seeing the tide and true Marshall and Fender circuits. Any help would be greatly appreciated!

I look forward to talking to my fellow tone freaks and EQ Tweaks! X]

xXBazookaJoeXx

I added the schematic below. The link wasn't working.

[J M Fahey]

Plug it into the 6505 cabinet and see the light.

[xXBazookaJoeXx]

Ya know I thought that the 8 inch speaker might be suspect. I never did try the 8Ohm speaker out.

[Roly]

Hi and welcome @xXBazookaJoeXx.

the low end is lacking extremely

To displace the same volume of air, as the speaker diameter goes down so the cone movement or "throw" has to increase.  By the time we are talking "bass" and "8-inch" we are talking about cone throws of a centimetre (half-inch) or more, and there are few drivers that can cope with this before frapping badly or spitting their smoking cone out on the floor.

Speakers can make a world of difference (particularly when you don't really have one).

It's a good bet that your problems would be fixed by a much bigger speaker in a much bigger box.

Sometimes trying stuff like feeding this amp into that box can produce some really surprising results.

I was looking at the schematic for it and I don't really understand it's EQ network! I'm used to seeing the tide and true Marshall and Fender circuits. Any help would be greatly appreciated!

Attached is the EQ circuit abstracted from the PDF above.

The treble section in the middle is straight out of the Jones tonestack.

The bass section is to the right.

The mid section is to the left and swings between being entirely C16 to being more R27C17.

The resistor chain R32, 33 and bass pot R31 determine the mix of the three sections into the output.

Really, the only way to get a handle on this is to model it in LT Spice.

In all passive tone controls the sections interact to some degree, but this shows the general signal paths.

cut more of the higher mids and less of the low mids

Then you are looking towards R27, 28 and C16, 17, 18.

attach:
Fender Frontman 25 EQ-annotated.gif

[xXBazookaJoeXx]

That helps out a bit. I tried LT Spice once and i had a hard time getting a handle on it. I do have Duncan Tonestack Calculator though. maybe I'll try to get a handle on LT Spice again.

[Roly]

I'm afraid that TSC won't get you very far with this one.