Fender FR-10/FR-12 noise reduction mod

For the sake of posterity, I tried out two OPA1604 chips in the 'noisy' 2nd and 3rd 14 pin slots. Soldering them on the adapter boards was not fun. I actually had another SOIC14 chip that I was going to try in that first position, but I grabbed it wrong with the tweezers and it flew across my basement, got zapped into another dimension, and was never to be seen again.

Anyway, there's no measurable or noticeable difference in hiss between the OPA4227PA PDIP14 chips and those two SOIC14 OPA1604 chips. My auditory hallucinations are telling me that the OPA4227PAs are slightly brighter sounding than the 1604s, but I'm slowly learning to ignore them.

OPA1604.jpg


-Aaron
 
Lysander said:
Be very weary when you find suspiciously cheap ICs in eBay, AliExpress and the likes.

9 times out of 10 those will be relabeled fakes.
Click to expand...
I bought some OPA4227PA from eBay, they were Burr Brown labeled ones. I have used a lot of BB and these appear legit. I have not tried them since I did not socket my amps.

I also got some from Mouser, labeled TI. I will use them if I ever go to replace the 1st place OPA4228PA if I should ever experience instability issues.
 
CraigB1960 said:
I bought some OPA4227PA from eBay, they were Burr Brown labeled ones. I have used a lot of BB and these appear legit. I have not tried them since I did not socket my amps.
Click to expand...

Honestly, it might be impossible to tell without actually testing them through dedicated gear. Most DIP-8 and DIP-14 opamps share the exact same pinout and have similar base specs, so it's incredibly easy to take a generic IC, relabel it Burr Brown, and sell it to someone who won't be able to tell the difference. Counterfeit semiconductors have been a serious problem for decades now.

If the price seems too good to be true... it very likely is.
 
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CraigB1960 said:
I bought some OPA4227PA from eBay, they were Burr Brown labeled ones. I have used a lot of BB and these appear legit. I have not tried them since I did not socket my amps.

I also got some from Mouser, labeled TI. I will use them if I ever go to replace the 1st place OPA4228PA if I should ever experience instability issues.
Click to expand...
Weird. The OPA4227PA I got from Mouser last week was definitely labeled Burr Brown.

It kind of struck me as odd that it looked physically more similar to the TL084CPs I got from them than the OPA4227PAs.

MouserChips.jpg


-Aaron
 
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aflynt said:
Weird. The OPA4227PA I got from Mouser last week was definitely labeled Burr Brown.
Click to expand...

Note that labeling is really the easy part when it comes to counterfeits :LOL:

Here's a fake OPA2134 from a quick Google search, vs a legit one. Most of the time these are relabeled TL074s, so the only way to tell for sure is to measure them in circuit, where performance (voltage offset, noise, supply current) won't match the specs for a legit BB.

IMG-6907.jpg
IMG-3523.jpg


Long story short: don't buy from dubious online listings. If the price is a fraction of what Mouser, Digikey et al lists, you're 99% certainly getting a fake.
 
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Lysander said:
Note that labeling is really the easy part when it comes to counterfeits :LOL:

Here's a fake OPA2134 from a quick Google search, vs a legit one. Most of the time these are relabeled TL074s, so the only way to tell for sure is to measure them in circuit, where performance (voltage offset, noise, supply current) won't match the specs for a legit BB.

IMG-6907.jpg
IMG-3523.jpg


Long story short: don't buy from dubious online listings at a fraction of the price on Mouser, Digikey et al.
Click to expand...
See above edited post. All three chips I got from Mouser.

-Aaron
 
aflynt said:
Weird. The OPA4227PA I got from Mouser last week was definitely labeled Burr Brown.

It kind of struck me as odd that it looked physically more similar to the TL084CPs I got from them than the OPA4227PAs.

View attachment 13907

-Aaron
Click to expand...

I just opened my Mouser packaged of OPA4227PA's. Though they are labeled as TI on package and description, they are BB. They look like your top package, which makes sense. Most likely the same lot and stock.

The ones I got from eBay look like your bottom (OPA4228PA) package and one of them is wrong, PGA2310PA, not an op-amp but an expensive chip.

On Digikey, the BB labeled OPA4227PA is listed at $7.28 @42. So it is not unreasonable for eBay venders to sell them for $7 to $8 if they purchased a bulk order or NOS. However I too do not trust eBay for chips.
 
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Lysander said:
Yeah, sorry, that wasn't specifically aimed at you. Just noting that "the package says BB" means absolutely nothing - it's incredibly easy to re-label ICs.

Buy from trusty suppliers, y'all.
Click to expand...
I fully agree. But, I can usually tell by the quality of the label. Hit it with some hi-power cleaner and see if it smudges is a dead giveaway.
 
I had some free time today so I swapped back TL084CNs one at a time in the two 'noisy' 14 pin positions (IC5 and IC8 on the PCB) and found that they both contribute a significant amount to the hiss with IC5 being the slightly more noisy one. I figured it'd be worth it to check to see if a one chip mod would work just as well, but both of those chips definitely need to be replaced to get rid of most of the hiss.

So if I was a frugal person who didn't like hiss, I'd just replace IC5 and IC8 with OPA4227PAs and be done with it. The combination of ICs that satisfied my auditory hallucinations in the most pleasing manner was replacing IC5 and IC8 with OPA1604s and IC1 with an OPA2134PA.

-Aaron
 
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aflynt said:
I had some free time today so I swapped back TL084CNs one at a time in the two 'noisy' 14 pin positions (IC5 and IC8 on the PCB) and found that they both contribute a significant amount to the hiss with IC5 being the slightly more noisy one. I figured it'd be worth it to check to see if a one chip mod would work just as well, but both of those chips definitely need to be replaced to get rid of most of the hiss.

So if I was a frugal person who didn't like hiss, I'd just replace IC5 and IC8 with OPA4227PAs and be done with it. The combination of ICs that satisfied my auditory hallucinations in the most pleasing manner was replacing IC5 and IC8 with OPA1604s and IC1 with an OPA2134PA.

-Aaron
Click to expand...
Man I hope you recorded the process for us idiots out there
 
So the FR12 landed today and I was afraid that Cordy’s influence may have set me up for yet another of many "FRFR" type disappointments.
But other than the inability to set loose flurries of liquid legato like he does it took me all of 5 minutes to realize his quick assessment was no hype.
I‘m keeping it and now there is no reason to keep the Kemper Stage and Kemper Cab Or any other "FRFR" gear.
FM9 and Helix stay for the next round of ‘play it or purge’ it.

The Tonemaster FR12 is legit! I’ll probably get a second one so I can have stereo once some of the stuff sells.
oh, no hiss either. Or maybe my tinnitus is the right frequency to mask it..lol
 
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I've swapped in 3 of the OPA4227PA chips. Would this change the frequency response in any way? I feel like something changed.
 
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