Universal Active Filter IC's

Thread Starter

rpschultz

Joined Nov 23, 2022
810
True and I agree. But I think failures of this type are extremely rare. I have owned 100s of pedals and have been active on music gear related pages (TGP) for 15+ years and I’ve never experienced nor heard of failures of this type.
 

MisterBill2

Joined Jan 23, 2018
27,522
I have repaired a few of these breaks, mostly on cheap consumer grade items, BUT also on a very expensive laptop computer.
And it is an unfortunate reality that cost reduction options are used even if they reduce quality and product lifetimes.

As long as the product does not fail during the warranty period the failure does not impact profits. If you have had no failures then perhaps you treat your equipment very gently. Some folks do that.

The force I am describing is not from operation of the control switch, it is from handling the box, moving it or dropping it, and vibration during travel between uses.
 

Thread Starter

rpschultz

Joined Nov 23, 2022
810
The most common problem I’ve seen is not on effect pedals, but on 1/4” or headphone jacks on other instruments and equipment, like pianos or e-drum modules. In both cases the jack is often simply protruding through the plastic, not clamped down to a chassis. So plug/unplug puts a force on the pcb joints as you suggest. But I pedals they are generally clamped down to metal box.
 

Thread Starter

rpschultz

Joined Nov 23, 2022
810
Here is one design I’ve been looking at in a 1590A box, I want my circuit to have a similar layout. Two 1/4” jacks and dc power on the bottom, pots/switch(s) on the top.

B8A1A405-00E0-4E25-8131-A2D0B18093FE.jpegEAE66C49-2071-46FB-8F8D-E1E1270117B2.jpeg
 

MisterBill2

Joined Jan 23, 2018
27,522
Certainly the three pots are well anchored to the board with their mounting tabs, but only the pots and the large switch anchor to the box.
The two toggle switches may be anchored by thru-hole leads, and probably the big button switch,, which since the PCB appears to be two-sided with plated thru holes, should be adequate. But the one black plastic jack I see appears to be a surface mount device with no support except for the solder connections. That part can certainly have problems, either solder breaking or the copper pulling off the board. I have seen both in consumer-grade electronic devices.
 

MisterBill2

Joined Jan 23, 2018
27,522
OK, it appears that bot 1/4 inch jacks securely mount to the box, but are only tied to the PCB with surface mount solder connections. And the power connector is not held by anything except some surface mount connections. Good luck with that!! When a solder connection breaks the operation will become intermittent.
 

Ian0

Joined Aug 7, 2020
13,132
I'm very curious why that LF353 is in a socket. Is it such as bad design that they have to select on test? Or is it such a bad design that the LF353 keeps failing and they have made it easy to replace? Why not a surface mount LF353 permanently soldered in place? That's not a cheap socket, wouln't some circuit protection have been cheaper? Or is it so that guitarists can keep swapping it until they get the perfect "tone"?
 

Thread Starter

rpschultz

Joined Nov 23, 2022
810
I'm very curious why that LF353 is in a socket. Is it such as bad design that they have to select on test? Or is it such a bad design that the LF353 keeps failing and they have made it easy to replace? Why not a surface mount LF353 permanently soldered in place? That's not a cheap socket, wouln't some circuit protection have been cheaper? Or is it so that guitarists can keep swapping it until they get the perfect "tone"?
Yeah I wondered that too. Becos is a small company from Romania of all places. But their line of compressors are cream of the crop. Seriously fantastic. But I can’t speak to their circuit design. Is there a better IC that I could swap?
 

Ian0

Joined Aug 7, 2020
13,132
Yeah I wondered that too. Becos is a small company from Romania of all places. But their line of compressors are cream of the crop. Seriously fantastic. But I can’t speak to their circuit design. Is there a better IC that I could swap?
That's something I couldn't say without knowing its function in the circuit. Is it in the signal path or the sidechain - or does it do both? TL072/LF353 are pretty good JFET op-amps
 

Ian0

Joined Aug 7, 2020
13,132
Looks like TL072H is a direct replacement. Does the H matter?
TLE2062 is meant to be an improved version, but I'd be very careful before changing it - does it have the same common mode input range, the same output voltage range, the same frequency compensation. All of these could turn a working pedal with a good op amp into a non-working pedal with a better op-amp.
 

MisterBill2

Joined Jan 23, 2018
27,522
IF that IC ever needs to be replaced then the socket will be a HUGE benefit. That is a double sided PCB with plated thru holes and probably tight fitting on the IC pins. So unsoldering the opamp would be a miserable destructive ordeal without the very best system. And it may be that not every IC they get passes the test prior to shipping. So using a better grade of socket will save them a lot of effort if ever they get a bad IC.
In addition, it clearly states that their products are worth repairing. Been down that road with a few product lines. The good sockets pay for themselves. At least we always verified that where I worked.
 

Thread Starter

rpschultz

Joined Nov 23, 2022
810
I emailed Becos, he recommended trying the Burr Brown series, something like OPA1656 or OPA2134 for subtle sound improvements
 

Audioguru again

Joined Oct 21, 2019
6,826
The LF353 datasheet does not mention audio or low distortion.
The TL072 datasheet says it produces only 0.003% audio distortion. Few people can hear less distortion than 0.1%.
The OPA2134 produces 0.00008% audio distortion and sounds the same as the TL072.

Don't guitar pedal circuits produce a massive amount of distortion and reduced bandwidth? "Fuzz Face".
Some people like to hear those awful and cheap sounds.
 

Thread Starter

rpschultz

Joined Nov 23, 2022
810
There are a plethora of pedals and types. Compressors though need to be clean, it shouldn’t add/subtract any harmonic content, just adjust dynamics.
 

Ian0

Joined Aug 7, 2020
13,132
There are a plethora of pedals and types. Compressors though need to be clean, it shouldn’t add/subtract any harmonic content, just adjust dynamics.
Somewhere in that circuit will be a voltage-controlled amplifier (unless it's an entirely digital pedal). That will make so much distortion (0.05% for a really good one) that the 0.003% from the TL072 will be insignificant. The TL072 will probably be an input or output buffer.
 
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