Fender Frontman 25R Series II

[Steve A.]

Does this amp have a different schematic and layout drawing from the original Frontman 25R which are on the Fender site?

The schematic for the original Frontman 25R is practically identical to that of the Champion 110 and Champion 30 amps which I had thought were the last of the breed of 100% analog ss amps in the Fender corral. The Champion 110 & 30 amps have a really great Normal channel which gets even better with a few circuit mods (I need to turn the treble WAY down to get a usable sound from the stock amps.)

Thanks!

Steve Ahola

[Enzo]

Call Fender and ask them. They usually don;t balk at schematic requests that are not already posted on the web site.

[Steve A.]

Call Fender and ask them. They usually don't balk at schematic requests that are not already posted on the web site.

The only phone number I could find on their site is for corporate headquarters (480)596-9690. Is there a better number for me to call?

Thanks!

Steve

[Enzo]

Well, that would have worked, ask for customer service or tell the operator you need schematics. Fender is a big company, but not as big as GM or the Pentagon, the front desk will get you there.

The consumer dial up I have on record is 480-596-7195.


There is a number intended for dealers etc, but they have a phone option for if you are a consumer, so why not - 800-488-1818. I have an inside service toll free that I won;t give out, so 1818 seems more like for everyone.

[Steve A.]

Well, that would have worked, ask for customer service or tell the operator you need schematics. Fender is a big company, but not as big as GM or the Pentagon, the front desk will get you there.

It's not the size of the company that matters but how screwed up their voice mail system is. There are several companies I deal with regularly that must have bought their voice mail system from Satan himself. With one company each time you are transferred the volume is cut about 10 or 20%.
The worst VM system I'd seen was one at a former employer who bought it used through a barter club. Such a deal. Turns out that the company who had owned it had gone out of business which I suspect was due in part to their screwed-up voice mail system. Among other dubious features when you were on hold a recorded message would come on every 45 seconds instructing you to press "1" to continue holding (if you didn't press "1" you were disconnected.) If no one picked up after 5 minutes it would often just drop the call. Practically every customer I talked to complained about our voice mail system.

There is a number intended for dealers etc, but they have a phone option for if you are a consumer, so why not - 800-488-1818. I have an inside service toll free that I won;t give out, so 1818 seems more like for everyone.

800-488-1818 worked great! I pressed "1" and got a real person immediately who emailed the schematic as we spoke. I attached the PDF file that they sent me.

Frontman 25R (Series II).pdf

Thanks!

Steve

[Enzo]

And so, now that you have it, how does it differ from the older one?

[Steve A.]

And so, now that you have it, how does it differ from the older one?

The big difference I've noticed so far is that the Ext Spkr jack is gone replaced by two RCA jacks for the audio input. The board layout is very similar to the Champion 30 and Champion 110 although there are changes in the reference numbers.

The Frontman 25R has a cheaper speaker than the Champion amps and the spring reverb unit is different- it is a plastic framed Ruby Tubes Reverberation Unit mounted to the sloped bottom of the chassis with 4 screws (the Champions had the springs inside a square cardboard tube mounted to the chassis with foam weatherstripping.) Most of the user reviews recommend replacing the FM25 speaker and I agree with them.

The Series II schematic is dated Feb '02 while the original FM25R was dated 2 years earlier in Feb '00. Perhaps the original was made in Mexico while the Series II PR498 is made in Indonesia...?

I still need to crop the schematics so that they are easier to read on letter-sized paper- I'll put together an expanded PDF file and upload it here.

Steve

P.S. Do you have the "PR" number for the original Frontman 25R?

[Enzo]

I'll see, you are the first person I have ever known to use the PR numbers.

OK< I have FM25R (Mexico) which was PR356 1997, and now that I look, it also has the series II as a later version in the same file, the schematic you linked, the PR# for that is PR498 as you can see up in the corner. The FM25R (Import) [as if Mexico was not an import, but to them it means Indonesia] also is PR498, though there is a revision B which does not show a PR#. It is dated 2000 and calls itself a series 2.

On the import, rev B uses an LM3876 power amp, while the rev A uses a TDA1514A. The board layouts differ mostly in spacing as a lot of the caps are now axial leads in rev B.

The Mexico original 1997 used the uPC1188 power amp. The mexico file series 2 uses the TDA chip.

I am not at all surprised that the entry level amps all look a lot alike inside.

[Steve A.]

I am not at all surprised that the entry level amps all look a lot alike inside.

Can't get enough of a good thing, eh? While the Frontman 25R is definitely entry level the Champion 30 is of comparable build quality to the Princeton 65 which I think is gig-worthy. Or giggity-giggity as Quagmire would say...

I think that Fender came up with some pretty good ss preamp designs which they also used in the 90 watt Deluxe 90 and 160 watt Stage 160. Pre-DSP, of course. For current production amps the 100 watt Frontman 212 looks gig-worthy with basically the same clean channel as the Princeton 110 and 65 (with the addition of a Mid control)- I just checked the Fender site and it looks like the 3 Frontman amps are the only 100% analog solid state amps that they are still selling. Or are the current Acoustasonic 15/100/150 amps 100% analog, too?

I'm modding my Champion 30 to bring along to jams and my Princeton 65 for small gigs. 100% analog solid state is where it's at!

Steve

[Steve A.]

Enzo:

Do you have a schematic for the Frontman 212R PR558 newer than the one on their site dated July 3, 2003? I was looking at the tone stack and there is a connection missing between C27 and R47 and was wondering if there is a newer schematic with that error corrected. The drawing I have is # 0061536000 Rev A. and the missing connection is in Row D right on the border between Column 3 and 4. (I'm studying the evolution of Fender ss designs- the tone stack in particular.)

Yes, I know I can call Fender support but I would much rather just email them. Hmmm... let me try that!

EDIT I just emailed them and will let you know what I get (it could newer than what you have- I dunno.)

Steve

P.S. I see that Fender has FINALLY corrected the labeling of the initial gain stage U1-A in all of these amps (Champion, Princeton, Frontman) going back at least to 1992 (I guess that they like to cut and paste!) The earlier drawings showed the feedback loop connected to terminal 3 instead of 2 and I was wondering if I was missing something...

[Enzo]

Oh my, I never look at them that closely, unless I am working on that exact spot in the circuit. Revision B is the same in the tone stack. DOn't expect a lot of offort from Fender documenting this amp, it is to them entry level and disposable.

They DO like to cut and paste. If they say to themselves, say lets take that opreamp but stick a 60 watt PA after it, there is no point in redesigning the preamp. And they're not going to build from the wchematic, the board lists and CNC stuff is long completed, so any typos in the drawings will just pass along.

I once had a lengthy discussion with a Peavey engineer about schematics, and it took several back and forths before he even got what I was talking about. The 5150 drawings are not really system schematics like the 5150-2 ones are. On page two for example is a lonesome triode with in and out signals named NEXT. Obviously no one sat down at his desk and thought, Hmmm, I need a triode that refers to vague other things. Clearly this was cut and paste from more systematic drawings. He eventually agreed that for a technician just wanting a whole amp schematic, this was not it.

Revs A and B are in this file.

[JoeM]

... (I'm studying the evolution of Fender ss designs- the tone stack in particular.)

...

Do you have the schematic for the Fender 85? I have one purchased in 1991, very nice cleans on this amp. I think these pre-date the Stage 100/Deluxe 90 SS amps. There was also a Deluxe 85 and IIRC a Stage 85 (?) from this era.

[Steve A.]

DrGonz78:

If you have schematics for some of the amps that JoeM mentioned email them to me and I will see if I can upload them.

JoeM

Thanks for the heads up on those models! I have a hunch that they are earlier versions of what I have been studying. Its not like the 90's preamp design popped out of Zeus' head fully grown.

The clean channel on the Princeton 112/65 amps has your basic BR/SF tone stack but with the values adjusted for the lower impedance of the IC stages. For example the bass cap is 0.47uF and the mid cap is 0.22uF with the resistances lower, not exactly divided by 10 by close. The P112 has a 470R ohm mid cap which is too low (Fender switched to a 1k8 cap in the P65.) I wired it up to a pot brought down from 5k to 1k7 by adding a 2k7 resistor and with a 470R resistor on the tail. So with the mid control at 0 it is identical to stock. (The Frontman 212R added a 5k mid control with no resistor on the tail. I found nothing useful for me higher than about 2k2.)

These amps are LOUD so I added a master volume by replacing the NFB resistor on the last stage before the FX loop with a pot. Smoothest MV I have ever added- completely transparent at 10 and it gives a very accurate reduction of the signal as you turn it down. (My first attempt was replacing the 100k resistor on the output of the IC with a 100k potentiometer. Although it was completely transparent at 10 the signal didn't sound that good as I turned it down and I was disappointed.)

I am going to start a thread over in Music Electronics about the tone stack used in many of the 90's models. It is between two gain stages and I thought it would be interesting to scale it for the higher impedance of tubes.

Steve Ahola

[Steve A.]

I got the Studio 85 schem from DrGonz78 but couldn't manage to attach it here- the program went through the motions but nothing was delivered...

Steve

[JoeM]

Steve,

The tone stacks on these amps (at least the ones I've seen) are factored compared to the typical BF Fender TS, by a factor of 5. So the 250k pots become 50k and the caps are close to 5x the BF values. 250pf treble cap on these becomes 1000pf for example, equivalent to a 200pf on the BF.