Fender FR-12 preamp mod : The Hissterectomy

To complete my answer, with the hiss that the FR-10/12 generates I find it almost unusable at low volume except perhaps by cutting the tweeter even more with the cut. By comparison, my CUBO is much more discreet and generates very little residual hiss for the same power range since the FR10/12 would be around 150W....I have no doubt that use at the sound volume of a group the breath will not bother anyone.... I can't hide my disappointment regarding an amp marketed by such a big brand. there are however some good ideas, the cut potentiometer which allows a dosage according to our ears is a good idea, I don't know if other manufacturers have already done this.
 
Just plugged in for 10 minutes yesterday - I have the fr-12 and the EV next to each other - on the floor with AB switch - The EV sounded boxy and small in comparison- the fender sounded fuller less detail in a good way which made the detail in the EV sound weird. I love the EV and have gigged it and as some have stated I think the EQ on the EV might get them close but I think the bigger size cabinet of the fender is helping a lot. Again just 10 minutes but very happy with the fender also didn’t hear any hiss but maybe just my old ears - will check that out further- so far Fender sounds great IMHO
 
200man said:
yer okay…just stay away from diming the fr12s volume
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WKSmith said:
Don't dime the fractal on +4 it will clip the 2nd stage and may burn out the compression driver over time from distortion.
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This is a great thread, I may do the mods over the winter.

Regarding the +4dB vs. -10dB - with the FR-12 - I reached out to Fender to get their perspective but haven't heard back yet. I admit, I'm still not sure which to use. Last night I set my FM3 to -10dB and I have to really push up the volume on both the FM3 and the amp.

Am I risking blowing out something in the amp if I use +4dB - I'd never have the need to dime the FR-12 but I also don't want to create a problem if the signal is too hot for the am. It doesn't say anything about the input signal in any documentation I can find.
 
daacrusher2001 said:
This is a great thread, I may do the mods over the winter.

Regarding the +4dB vs. -10dB - with the FR-12 - I reached out to Fender to get their perspective but haven't heard back yet. I admit, I'm still not sure which to use. Last night I set my FM3 to -10dB and I have to really push up the volume on both the FM3 and the amp.

Am I risking blowing out something in the amp if I use +4dB - I'd never have the need to dime the FR-12 but I also don't want to create a problem if the signal is too hot for the am. It doesn't say anything about the input signal in any documentation I can find.
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Yeah, there is no documentation about input levels or input impedance or what happens if you plug the xlr out into a pa with phantom power turned on.

The gain is just too high for dimed out +4. You can just pull the output level down a little bit on the Fractal and use +4.

The gain is fixed (incorrectly) in the FR-12 and then the volume pot dumps all that gained up signal straight to ground before the eq.

The clipping could blow out the diaphragm in the compression driver over time. That's really the only major concern.
 
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daacrusher2001 said:
This is a great thread, I may do the mods over the winter.

Regarding the +4dB vs. -10dB - with the FR-12 - I reached out to Fender to get their perspective but haven't heard back yet. I admit, I'm still not sure which to use. Last night I set my FM3 to -10dB and I have to really push up the volume on both the FM3 and the amp.

Am I risking blowing out something in the amp if I use +4dB - I'd never have the need to dime the FR-12 but I also don't want to create a problem if the signal is too hot for the am. It doesn't say anything about the input signal in any documentation I can find.
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It’s tricky because it also depends on how hot your patches are with your guitar and playing. For what it’s worth, my patches average around 0db on the meters in the Fractal occasionally peaking in the red a bit. I set the out to +4 with the FM3 output level knob on about 3/4. I use the volume knob on the Fender to get me to the right level for the show.

-Aaron
 
WKSmith said:
Yeah, there is no documentation about input levels or input impedance or what happens if you plug the xlr out into a pa with phantom power turned on.

The gain is just too high for dimed out +4. You can just pull the output level down a little bit on the Fractal and use +4.

The gain is fixed (incorrectly) in the FR-12 and then the volume pot dumps all that gained up signal straight to ground before the eq.

The clipping could blow out the diaphragm in the compression driver over time. That's really the only major concern.
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aflynt said:
It’s tricky because it also depends on how hot your patches are with your guitar and playing. For what it’s worth, my patches average around 0db on the meters in the Fractal occasionally peaking in the red a bit. I set the out to +4 with the FM3 output level knob on about 3/4. I use the volume knob on the Fender to get me to the right level for the show.

-Aaron
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Thanks guys...my gig last Saturday was with the FM3 at +4dB and I recall the FM3 output dial set around 1/2 up, then just adjusted using the amp volume. I guess I'll just keep it that way for this weekend's gig.
 
I have a rehearsal Tuesday and I am bringing the FR. I am thinking about a different approach to gain staging it. I am going to try it today.

I think that if the 2nd stage is biased properly to make a dimed +4 input tickle the red..

Then the not so obvious approach is to turn down the Fractal out level to zero, turn the FR amp volume on 10 (won't affect the hiss) and bring up the Fractal out level up to wherever the stage volume needs to be.

I think that is a better solution than cranking the Fractal up and then dumping that signal with gain to ground with the FR volume knob. it sucks don't even try it 🤣
 
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WKSmith said:
I have a rehearsal Tuesday and I am bringing the FR. I am thinking about a different approach to gain staging it. I am going to try it today.

I think that if the 2nd stage is biased properly to make a dimed +4 input tickle the red..

Then the not so obvious approach is to turn down the Fractal out level to zero, turn the FR amp volume on 10 (won't affect the hiss) and bring up the Fractal out level up to wherever the stage volume needs to be.

I think that is a better solution than cranking the Fractal up and then dumping that signal with gain to ground with the FR volume knob.
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Fractal output level control might get pretty twitchy sensitive run that way, depending on how the levels work out.
 
WKSmith said:
It sucks. Nevermind 🫤
It makes the hiss worse.
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I'd think fractal output (1or 2) at noon, FR-12 to as high as noon. If noon on the FR-12 isn't loud enough then start raising the Fractal to maybe 3:00, then back to the FR-12. And if that isn't loud enough, your presets probably aren't leveled high enough because that should get super F'n loud.
 
I made a new, longer comparison using the FM9 looper in order to have a more detached listening experience....between the CUBO and the FR-10 alternating on the 2 amps.
This confirms my first impression. The Fender is pleasant to listen to but I have much less breath on the CUBO, the double amplification of the CUBO (Stereo) brings more punch.

I'm not keeping the FR-10, but I will continue to read with interest the discussion thread and the modifications that some will make on the FR-10/12.

The cbellanga modification seems to solve this hissing problem so why didn't Fender do something similar? this would not have caused the price of the amp to rise recklessly...

I refuse to do any kind of customization even if electronics are part of my professional skills. because the amp would be very difficult to sell second-hand and the manufacturer's warranty would disappear.
 
Lolo-G said:
The cbellanga modification seems to solve this hissing problem so why didn't Fender do something similar? this would not have caused the price of the amp to rise recklessly...
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It would. The opamp change i proposed, and people here confirmed as working, is 20x more expensive (in bulk) than the stock TL084s in the FR-10 and 12. These are premium, ultra-low noise parts.

Thing is, super low noise ICs should've been never necessary to begin with. Fender just needs a preamp redesign requiring half the number of opamp stages - if not less. And as @WKSmith pointed out, this is absolutely doable.
 
Lysander said:
It would. The opamp change i proposed, and people here confirmed as working, is 20x more expensive (in bulk) than the stock TL084s in the FR-10 and 12. These are premium, ultra-low noise parts.

Thing is, super low noise ICs should've been never necessary to begin with. Fender just needs a preamp redesign requiring half the number of opamp stages - if not less. And as @WKSmith pointed out, this is absolutely doable.
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So I'm waiting for a FR-10/12 V2 with a new preamp and an axial tweeter....
 
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