Fender FR-12 preamp mod : The Hissterectomy

Greg Ferguson said:
If Fender has executives who care, they are probably watching this progress and will drag in the designers of the circuit board at some point and want to know why they didn't do this. And when they see the lame excuses and attempts to gaslight in their posted responses there should be some very uncomfortable moments in their shiny new co-headquarters.

A response that flat is great, but what will the speaker and cabinet do to it? If they ruin the flatness, does it make sense to be able to run the output of your board into a different power-amp and cab/speaker so it can kill two birds with one stone?
Click to expand...

The low end being that flat can only improve the bass response down to the resonant freq of the speaker (55Hz ish if I recall) and the port tuning. I will highpass that low end upwards a little bit in the last crossover stage. There is no need to have flat bass response down to 10Hz in this FR system. But it is a nice place to start from. ... instead of adding eq to get that bass response back.

And yes ..this preamp is better suited for a really nice power amp solution and a co-axial driver. That is the real reason behind doing this right. Fixing the FR is just a bonus. There is a lot of possibility for this preamp in the FRFR space.
 
Last edited:
Just fixing the phantom power issue is reason enough to do a mod like this. I do wonder if there will be a sonic difference overall with the preamp mod outside of the reduction of the 'hiss'. Most reviewers I heard said outside of the hiss the unit sounded really good.
 
Nsurround said:
Just fixing the phantom power issue is reason enough to do a mod like this. I do wonder if there will be a sonic difference overall with the preamp mod outside of the reduction of the 'hiss'. Most reviewers I heard said outside of the hiss the unit sounded really good.
Click to expand...
Without giving away too many details yet..

Yes. There are many sonic improvements in the eq. The bottom end is a little lower. The mids have more balls. The high end is sweeter and more refined. The crossover notch is gone as the crossover is tuned properly.

And some functional improvements.. like adding a clip light and better shielding from EMF, An optional mute/standby switch, socketed ICs so you can roll your own, premium components and nice custom pots that have 40 clicks for precise knob settings that stay put.

The design has way less components than the stock board and 8 opamp channels instead of 16 amps.

And with that savings... a damn sexy gold plated circuit board
 
WKSmith said:
Without giving away too many details yet..

Yes. There are many sonic improvements in the eq. The bottom end is a little lower. The mids have more balls. The high end is sweeter and more refined. The crossover notch is gone as the crossover is tuned properly.

And some functional improvements.. like adding a clip light and better shielding from EMF, An optional mute/standby switch, socketed ICs so you can roll your own, premium components and nice custom pots that have 40 clicks for precise knob settings that stay put.

The design has way less components than the stock board and 8 opamp channels instead of 16 amps.

And with that savings... a damn sexy gold plated circuit board
Click to expand...
One of the things people are always wanting the FM3 to have is a powered USB-A port. Maybe such a thing on your board to supply a USB-A and a USB-C could really blow Fender's mind and have people racing to your upgrade/fix? I always lean toward plugging something into the power strip, but, well, you know, "people". :) The downside is that those ports are fragile and prone to damage.
 
WKSmith said:
Without giving away too many details yet..

Yes. There are many sonic improvements in the eq. The bottom end is a little lower. The mids have more balls. The high end is sweeter and more refined. The crossover notch is gone as the crossover is tuned properly.

And some functional improvements.. like adding a clip light and better shielding from EMF, An optional mute/standby switch, socketed ICs so you can roll your own, premium components and nice custom pots that have 40 clicks for precise knob settings that stay put.

The design has way less components than the stock board and 8 opamp channels instead of 16 amps.

And with that savings... a damn sexy gold plated circuit board
Click to expand...
Great to read.
 
Greg Ferguson said:
One of the things people are always wanting the FM3 to have is a powered USB-A port. Maybe such a thing on your board to supply a USB-A and a USB-C could really blow Fender's mind and have people racing to your upgrade/fix? I always lean toward plugging something into the power strip, but, well, you know, "people". :) The downside is that those ports are fragile and prone to damage.
Click to expand...
Those are some problematic jacks for sure.
I may lean towards that for another preamp, but this one needs to use existing FR chassis holes and stock wiring harnesses.
 
WKSmith said:
The filters I used are tuned close to the factory settings, but the factory mid is asymmetrical.. my tuning is not. The highs sound less harsh and more musical. The cut isn't for cutting hiss anymore, so the knob has more useful range.

My filters just sound better. Without the hiss.
Click to expand...

I’m sold. Will this work in both units 10 and 12”?
 
I May Need Two Billy Ray Cyrus GIF by Still The King
 
fsharpminor said:
one other question....is the xlr out that youve now shielded from phantom pre or post the eq circuit (and could this be switchable?)....im absolutley in either way, but that might be an idea for the 'perfect circuit'.....
Click to expand...
The xlr out is built into the stock input board. It is a copy of the xlr input.
Phantom power protection is in front of the preamp to protect the ICs between the input board and preamp.
The preamp has two outputs from the crossover. One out drives the 150w class D amp for the 12 or 10" driver, the other out drives the tiny onboard class A/B amp for the compression driver.
There are no external outputs post eq.

To add one would require building a new input board. I may look at that after the preamp is finished, but I am building the pre to plug into the stock input and power supply/pass thru boards.
 
You must log in or register to reply here.
Back
Top Bottom