Fender FR-12 preamp mod : The Hissterectomy

aflynt said:
Seems like in the case of a hypothetical SPDIF in on the FR-12 being fed by a Fractal, you'd only be moving the D/A conversion from one device to another. Not sure what the advantage would be there. If there was DSP in the FR-12 it'd make more sense I think.

-Aaron
Click to expand...
Good point
 
Agree with @aflynt.

One of the reasons I bought the AF3 in the first place is because of the quality of the converters and the components situated around those converters.
 
I use the s/pdif output from my FM9 to the s/pdif input on a presonus Quantum 2 for recording and practicing when I am using the home studio. Have not noticed any latency issues but yeah the cabling could be an issue in a live situation. Should use a 75ohm cable either with an RCA connector of better yet a video bnc one. Could also be an Optical Tosh type link but not really feasible in a live situation unless your FM is fairly close to the amp etc.
 
WKSmith said:
I am seriously thinking about using an inexpensive IcePower amp (with power supply) and a coax driver DIY build
with a version of this pre as an option .. perhaps even with a S/PDIF digital input.

So we can diy a killer affordable FRFR ourselves.
Click to expand...
Didn't mean to derail your thread but I would be really interested in something like this! I want to be able to do a Vertical 212 type of deal with some sort of power amp that is an all in one like the Laney version but about a 1/3 of the cost.
 
Sixstring said:
Didn't mean to derail your thread but I would be really interested in something like this! I want to be able to do a Vertical 212 type of deal with some sort of power amp that is an all in one like the Laney version but about a 1/3 of the cost.
Click to expand...
I would love to try the F 150 triple cone and a fx 200 coax in the same cabinet as a vertical powered 2x12 .

Like ..I seriously want to build a pair of those.
 
As I promised. Here is the cheapest and easiest way to kill (most of) the hiss in a FR-12 or FR-10.

Kill the nasty eq with a piece of wire.

Pull the bottoms (or the entire thing) from 2 jumpers JMP10 and JMP 29 and connect the bottom terminals together with a piece of wire.

And done.
This removes 12 amp stages of really bad design. It connects the first 2 stages with the last 2 (crossover) stages.

You can cut the jumpers and bend them out of the way and solder the bottom half(s) to a piece of wire if you don't want to pull the board out.

Carefully though. These are cheap single sided boards and you can easily pull the whole solder pad off and some of the trace with it.

This keeps the freq curve mostly intact, except for a little more highs and a little less lows. It's really simple and easily reversible.

IMG_1433.jpeg

You can then re-create the eq in a block

3 band pass (peaking) filters:
Bass= 80Hz
Mids = 500Hz
Highs = 3.75 kHz

The cut is 3K and up
(high pass shelving.. cut only)

Bonus points if you also
high pass at 70Hz
And low pass at 7kHz
(Both shelving)
 
Last edited:
WKSmith said:
As I promised. Here is the cheapest and easiest way to kill (most of) the hiss in a FR-12 or FR-10.

Kill the nasty eq with a piece of wire.

Pull the bottoms (or the entire thing) from 2 jumpers JMP11 and JMP 29 and connect the bottom terminals together with a piece of wire.

And done.
This removes 12 amp stages of really bad design. It connects the first 2 stages with the last 2 (crossover) stages.

You can cut the jumpers and bend them out of the way and solder the bottom half(s) to a piece of wire if you don't want to pull the board out.

Carefully though. These are cheap single sided boards and you can pull the whole solder pad off and some of the trace with it.

This keeps the freq curve mostly intact, except for a little more highs and a little less lows. It's really simple and easily reversible.

View attachment 134996

You can then re-create the eq in a block
Bass= 80Hz
Mids = 500Hz
Highs = 3.75 kHz

The cut is 3K and up

Bonus points if you also
high pass at 70Hz
And low pass at 7kHz
Click to expand...
You’re really making Fender look stupid. Good job!
 
Greg Ferguson said:
You’re really making Fender look stupid. Good job!
Click to expand...
I'm not here to sell preamps 😉👍

🤣😂😅

This is example of them making themselves look stupid. Those jumpers.. there are 30 or so of them
..so they can use a single sided board and save just a few cents. But it has no ground plane on the top side (which faces to the front of the FR and is pointed straight at the guitar pickups) and the chassis is not a complete shielded enclosure, more like an L shape. That's just dumb!

Whoever designed this pre has a bright future building curling irons and coffee pots.

How a legacy brand like big-F put this out and put their name on it (after a year and 3 revisions and a secret IC swap "hiss fix") is beyond belief.

Here's some pro advice for F-corp "engineers"...

1) Buy a Doug Self book on small signal audio, especially the gain staging and filter design chapters, and maybe even power amp design, and read it... Twice

2) Buy a Walt Jung book before buying ICs, and learn how to read a dang data sheet.

3) Fire the accountant that built this pre.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom