Fender FR-12 preamp mod : The Hissterectomy

jellodog said:
WOW! You actually made the effort to colour-match the components to a blue and grey scheme.

🤯

Amazing.
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The resistors are blue because that is the common color for precision 1% metal film.

Many of the grey box caps I have here already, so in ordering the ones I needed for this build I asked suppliers specifically for grey, and refused any of the cheaper yellow ones. ( I am also not using the much less expensive red dipped Mylar or green dipped polypropylene )
These box caps have really tight tolerance % between a whole bin full of parts and are potted in epoxy.

The lone blue box cap on the far right is a Wima Film/Foil that is a critical value for tuning the crossover.

The TDK/Epcos caps in the current assembly are dark blue. You will see those phasing out some of the grey ones soon.

Even the tiny pF value blue caps have a very tiny % tolerance too.

All these V2 caps measure with exact values through the entire batches of the same value caps down to a fraction of one percent.

I randomly pull out several from each value and actually measure the difference. The low % tolerance is quite remarkable.

... and yes it looks pretty cool too.
 
Budda said:
im buying one but dont own a Fco unit either.. yet..
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I don't have a FR-12 yet.

Heck, I don't even have any Fractal gear (I'm a Helix guy).

But I've committed to buy a V2 a long time ago.

... and maybe an FM9 in the future! :sweatsmile:

You know, I've always heard some bad things about "Fractal people" in some other forums, but my experience here in this thread has completely removed every ounce of unreasonable prejudice that I may have had before.

I've came here, learned lot and witnessed a couple of very passionate people (specially the OP, of course), trying to fix a product and make a difference for everyone, without any distinction.

You guys are really great! And this thread is gold.
 
So here is the difference in the way the V2 mounts vs. the stock preamp.

The stock pre mounts facing the front of the amp to studs in the back plane of the chassis.
This exposes it to all kinds of interference (and faces the power amp board). It is especially noisy when sitting right next to a tube amps power transformer side. Dumb. AF. Especially for a single sided board mounted in an open chassis.

IMG_1581.jpeg


The V2 is firmly mounted to the backside of the pots. It also has solid polygon ground plane pours on both sides of the board. The exposed side is now facing down and is oriented with its tiny side profile at at a right angle to the power supply board EMF.. and is much smaller so it's offset forward and to the left a good bit. It is quiet as a mouse ..even right next to a huge tube amp power transformer lit up.

IMG_1582.jpeg
 
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Chewie5150 said:
I may have missed this in the thread but for the beta testers what was the general finding in terms of optimal settings. Obviously everyone's room and ears are different but the stock versions there was some common eq settings to make it more flat...
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I am going to tag the Beta testers, except for Joe of course 🤣 he won't get his till Tuesday.
Paging @Deadpool_25 @Lysander

But we should all talk about the eq soon. It does some awesome stuff that the stock one can't with 1/3 of the amp channels of the stock design. It's kinda badass.
 
yyz67 said:
Pretty as fuck.

Is the symmetrical component arrangement purely aesthetic or does it minimize noise/EMI?
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The layout is mostly aesthetic. But the EMI/EMF is way better, mostly from the grounding and the board orientation. I do use right angles to cross traces in routing the top and bottom layers, and use a really heavy buss for both V+ and V- on separate sides of the board, and there are zero! Vias in the routing... And I understand that magnetic fields propagate at right angles to the current, right hand rule, and basic design principles.

There is a valid design point to be made though.. like the foil ends of capacitors orientation to the low impedance side, but this is a DC preamp, so it doesn't need as much AC protection like the HT tube amp circuits do.

I use Sacred Geometry and Platonic Solids in my art and design, I am sure there is a benefit... but I could have improved on the stock design with a blindfold, some darts, and a donkey. 🤣
 
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every day when I check my mailbox I like to pretend the V2 is going to be there.

It’s probably a good time to admit a few things:

-I don’t understand 99% of what comes out of @WKSmith mouth

-I haven’t turned on the Fr10 since I stumbled upon this thread. I refuse to even look at it.

-the V2 project inspires me to be more conscious of the work I do. I tend to focus on path of least resistance and easier faster cheaper solutions, but seeing people going the extra mile to make better things (when even a half assed v2 would have been an improvement) is enlightening

- what am I going to do these OPamps from mouser? Anybody want them? I never attempted to install them
 
LolainNB said:
every day when I check my mailbox I like to pretend the V2 is going to be there.

It’s probably a good time to admit a few things:

-I don’t understand 99% of what comes out of @WKSmith mouth

-I haven’t turned on the Fr10 since I stumbled upon this thread. I refuse to even look at it.

-the V2 project inspires me to be more conscious of the work I do. I tend to focus on path of least resistance and easier faster cheaper solutions, but seeing people going the extra mile to make better things (when even a half assed v2 would have been an improvement) is enlightening

- what am I going to do these OPamps from mouser? Anybody want them? I never attempted to install them
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But Tevye... do you love it? :D
 
So, I had an FR-10 on order with GC. Apparently, they are not expected in until August. Yes, it was offered at a discount, but then I found a returned one. So, I finally have one on the way. I'm expecting to hear this dreaded hiss. And actually, it will be nice to hear the comparison between the stock and the WKS upgrade. Thanks again! Really looking forward to it.
 
WKSmith said:
The layout is mostly aesthetic. But the EMI/EMF is way better, mostly from the grounding and the board orientation. I do use right angles to cross traces in routing the top and bottom layers, and use a really heavy buss for both V+ and V- on separate sides of the board, and there are zero! Vias in the routing... And I understand that magnetic fields propagate at right angles to the current, right hand rule, and basic design principles.

There is a valid design point to be made though.. like the foil ends of capacitors orientation to the low impedance side, but this is a DC preamp, so it doesn't need as much AC protection like the HT tube amp circuits do.

I use Sacred Geometry and Platonic Solids in my art and design, I am sure there is a benefit... but I could have improved on the stock design with a blindfold, some darts, and a donkey. 🤣
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I appreciate all the work and obvious passion you’ve put into this project.

One question… I see that many of the components are in square clusters with the components seemingly right up against each. Are there any issues with heat dissipation?
 
MLocascio said:
I appreciate all the work and obvious passion you’ve put into this project.

One question… I see that many of the components are in square clusters with the components seemingly right up against each. Are there any issues with heat dissipation?
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Not at all. Those are resonant circuits that tune the filters. They are very low line level small signal devices.

The only signigant heat is from the horn amp IC, and I used a much better heat sink than the stock preamp uses there.
 
WKSmith said:
Not at all. Those are resonant circuits that tune the filters. They are very low line level small signal devices.

The only signigant heat is from the horn amp IC, and I used a much better heat sink than the stock preamp uses there.
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Great, thanks for the explanation. Looking forward to getting the V2!
 
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