Fender FR-12 preamp mod : The Hissterectomy

[WallyG3]

I can relate with the strat wiring! Been there many times.

A drop in solution that requires no soldering is a complete preamp build. Easy on y'all , but hard, a lot of hours, and expensive on me. This is what I want Fender to do.

A drop in board that requires a little soldering and cutting out some stuff, that uses their first 2 and last 2 amp stages and their on board power amp... is pretty easy to do and not terribly expensive. And will solve the hiss completely, but it will mean a lot of emails and customer support from me.....And it exposes my eq design to anyone.. cough cough Uli Behringer.

Bypassing the eq is one wire, cutting 2 jumpers, and adding a 10k bias resistor to the last (crossover) stages. It would need 2 bands of global eq, and a tuned PEQ block would be the eq. That's gonna be free if they don't want to play.

Fender, your move

I'm open to buying a PCB with an instruction sheet and NDA, lol.

 

[200man]

No they are old school analog! PTH full size components... like back when stuff sounded great. Way back before surface mount toaster oven tech made the components cheaper than a grain of rice in china.

This may be the last piece of vintage Audio gear mass produced the old way.

God bless 'em

Have to re-visit this.
So… mic’ed up the jbl “digital” pa I was using and got a direct out signal out its back and recorded them into Logic and the result was ~5ms.
I wonder if a part of the “feels like a cab” isn’t somewhat due to digital processing delay.

 

[WKSmith]

Have to re-visit this.
So… mic’ed up the jbl “digital” pa I was using and got a direct out signal out its back and recorded them into Logic and the result was ~5ms.
I wonder if a part of the “feels like a cab” isn’t somewhat due to digital processing delay?

Jbl is digital and has latency... if I recall correctly, which your test proves. Bravo!

There is no delay in the FR-12 it's analog
...so it's the speed of light.

The "feels like a cab" is definitely not delay.

 

[200man]

Jbl is digital and has latency... if I recall correctly, which your test proves. Bravo!

There is no delay in the FR-12 it's analog
...so it's the speed of light.

The "feels like a cab" is definitely not delay.

It feels more immediate. I never intimated it was THE cause but is a part.

 

[marsonic]

I think he meant the other way around, that the lack of delay is part of the cab feel.

IMHO, it's probably not.

It's possible that's the one proverbial straw that pushes the total latency over what you can tolerate, but...I think people wouldn't run wireless, let alone wireless to a modeler and then a digital mixer and then wireless to in-ears if it was that big of a problem.

 

[∞Fractals]

Isn’t 5 ms equivalent to 5 feet away from your cabinet; and then if you have 5 ms delay plus you’re standing 5 feet from your cab it’s kinda like standing 10 feet away?

 

[marsonic]

Isn’t 5 ms equivalent to 5 feet away from your cabinet; and then if you have 5 ms delay plus you’re standing 5 feet from your cab it’s kinda like standing 10 feet away?

No, it actually doesn't quite work like that if you know where the cab is. The brain is a very weird thing.

 

[WKSmith]

Delay is not an issue. But I appreciate the hell out of the feedback from fractal folks. All of you

 

[200man]

I’ll just say I love the lack of delay.

 

[WKSmith]

While I wait on parts here are my next mods:

1) I am going to go back to a trimmer for the gain. I will set it to saturate (tickle the red) when being slammed with +4 but not clip.

The trimmer is for setting the gain lower for a different IC. The opa2134 will play almost rail to rail ( +/- .7v ) or 34.6v (with a 36v supply)

The stock 4558 or the TL08x (used in the eq and other stages) will only take 30v before clipping. So those ICs would need to be biased lower.

So instead of a +4/-10 switch. I will squeeze as much gain from the factory setting as I can, without clipping at +4. And lock it in. But if I want to demo it for folks with a TL08x budget I can just set it lower to 30v at +4dB.

Because.... fender won't want to buy a switch. And probably not a BB OPA2134 front end either.

2) I'm going to tune the crossover to eliminate the notch at the crossover freq. it just bugs me personally, but it might sound different.

I want to let y'all vote on the difference between the crossover tuned properly, and stock ..with the big notch. Then I will set it and break off the knob. ... or leave it alone.

3) I am going to put 2 fast 2amp diodes interrupting the +/- supply rails to drop them to 36v . Because 37.2 Volts. ..is just stupid.

 

[dws2384]

Isn’t 5 ms equivalent to 5 feet away from your cabinet; and then if you have 5 ms delay plus you’re standing 5 feet from your cab it’s kinda like standing 10 feet away?

Ya but then you start adding 2-5ms here or there from modellers and effects loops running to other digital pedals and it adds up. I can’t really notice anything up to 10ms through headphones or sitting in front of monitors. Start adding 10ms plus standing 10 feet away from your output source and it feels like your drunk when you’re not and not in a good way

You can turn on a delay, set the mix to 100%, put on headphones and start turning the delay knob until you notice it. I find you’ll trick yourself into bias though. Way better test is to have someone else mess with the knob and see if/when you can actually tell.

 

[Piing]

Please, do not convert this thread into a latency sensitivity contest. Let's keep the topic on the hiss and the mods to solve the FR-12 issues

 

[dws2384]

Please, do not convert this thread into a latency sensitivity contest. Let's keep the topic on the hiss and the mods to solve the FR-12 issues

Hahaha. Fair enough. Sorry!

 

[Deadpool_25]

TL;DR: In the interim, to "solve" the hiss issue, crank the cut knob and recover the lost high end with a PEQ block.

While we all wait for the permanent solution, and since the cut knob reduces the hiss more and more as you turn it up, I decided to test an idea I had. Kill the hiss with the cut knob and recover the lost high end content via a PEQ block.

I started the test with just a synth block going through a PEQ block (bypassed) to the output. @WKSmith Identified that the cut starts around 3k. Targeting frequencies above that, I set the synth block to play a sine wave at 4k (the highest it goes; I was too lazy to use pink noise and the RTA app). I used an SPL app to measure the signal with the cut knob all the way down. I then turned the cut knob all the way up which reduced the to hiss to almost nothing but of course that also reduced the high end coming out of the FM9 too much. To regain that high end I engaged the PEQ block, set it to shelving, and boosted about 9db at 3k. That got the SPL app about the same. But that was just a sine wave at 4k. Not really all that valuable.

Next, I deleted the synth block, added an amp and cab, and shifted to playing some chords around the neck. I tweaked the EQ a little and settled on the parametric EQ having frequency 4 set to shelving, +6db @ 3k; frequency 5 set to shelving, +9 db @ 4k.

It was just a super quick proof of concept and I wasn't able to play very loud (about 85-90db) but I think it worked quite well overall. It would probably take some more tuning of the EQ and of course some testing at gig volume but it's looking like a pretty viable solution.

 

[vika12]

Seems to me that if you have to mod a brand new powered speaker there must be a better powered speaker out there somewhere ...

 

[Deadpool_25]

Seems to me that if you have to mod a brand new powered speaker there must be a better powered speaker out there somewhere ...

You don't have to mod it lol

But there could certainly be speakers out there that are better for you (keeping in mind that what's better for one person may not be better for another).

 

[WKSmith]

Seems to me that if you have to mod a brand new powered speaker there must be a better powered speaker out there somewhere ...

Absolutely! The Meyer or D&B offerings are very nice ...at the +$2k price point. And they still don't look like a backline.

For $500 nothing compares to the FR-12 in my opinion. Your experience and usage may be different.

 

[Piing]

Seems to me that if you have to mod a brand new powered speaker there must be a better powered speaker out there somewhere ...

Absolutely. I wish I could grab a Meyer Sound ULTRA-X20. Zero hiss. Wide and customizable coverage with two 5” cone drivers, one 2” diaphragm compression driver and a rotatable 110°x 50° horn in a coaxial configuration. Class D amplifier, and a beautiful frequency curve.

 

[WKSmith]

Absolutely. I wish I could grab a Meyer Sound ULTRA-X20. Zero hiss. Wide and customizable coverage with two 5” cone drivers, one 2” diaphragm compression driver and a rotatable 110°x 50° horn in a coaxial configuration. Class D amplifier, and a beautiful frequency curve.

View attachment 128761View attachment 128760

That is a beautiful thing!!!

 

[200man]

Absolutely. I wish I could grab a Meyer Sound ULTRA-X20. Zero hiss. Wide and customizable coverage with two 5” cone drivers, one 2” diaphragm compression driver and a rotatable 110°x 50° horn in a coaxial configuration. Class D amplifier, and a beautiful frequency curve.

View attachment 128761View attachment 128760

To each his own of course. Personally, and this is just me, I love the sound of the Fender. And I do not like digital latency and I like a speaker that looks like a guitar cab and i like the eq and tilt backs. Again it’s just my opinion.

PS This is the only highly tweakable product I’ve seen of this type.