Lets squeeze some oranges

[OiMcCoy]

I am sorry if this has been done to death, but using the search I have not been able to find a comprehensive answer to all my questions.

So lets talk about the Orange Squeezer!

So I am highly interested in making myself (and potentially more for sale) an OS. I am a sucker for 'auto' compression, as years of being a FOH tech has left me with a very pronounced Control Fiddling Syndrome. Time and maturity have taught me that in a lot of cases, less it more. So I am less interested in mods that expand the control features. Maybe that will be something I revisit in the future but for now I am looking to make something that just works. I also want to make it better suited for bass... because that is mostly what I play. Tho if I want to sell a few units, I don't want to make something exclusive to bass.

Now I am trying to find all the parts I need and it looks like 2n5457's are hard to come by these days. Instead of risking buying fakes, I am wondering if the much more available 2n5458's would work as a suitable replacement. As far as I can tell they are just slightly lower gain. The other hard to find part is the JRC4558 IC. I also have had builds in the past where the 4558 had been problematic. Issues that were all solved by replacing it with a L072. I am hoping that this would work here as well.

Apart from finding all the right parts, are there any pitfalls of the original design that has since been 'solved'? I would be including a power supply filter. But what else should I be keeping and eye out for?

I am really hoping I can make this work for my needs, as I have already mocked up a design that I am would love to see become a reality.

[garcho]

No offense, but it very much has indeed been done to death. Try searching with google instead of here. Like this:

orange squeezer site:www.diystompboxes.com

[rockola]

2n5457's are hard to come by these days.

MMBF5457

[EBK]

2n5457's are hard to come by these days.

MMBF5457

And, if you are a bit nervous about the MMBF5457 being a tiny surface mount device, take a deep breath and relax (but don't take a deep breath too close to a loose MMBF5457  ):
https://www.diystompboxes.com/smfforum/index.php?topic=126111.0

Go for it! 

[OiMcCoy]

2n5457's are hard to come by these days.

MMBF5457

And, if you are a bit nervous about the MMBF5457 being a tiny surface mount device, take a deep breath and relax (but don't take a deep breath too close to a loose MMBF5457  ):
https://www.diystompboxes.com/smfforum/index.php?topic=126111.0

Go for it! 

Might be a stupid question, but if I am designing the PCB, I would just be adding an extra step by doing this method, no?

[EBK]

2n5457's are hard to come by these days.

MMBF5457

And, if you are a bit nervous about the MMBF5457 being a tiny surface mount device, take a deep breath and relax (but don't take a deep breath too close to a loose MMBF5457  ):
https://www.diystompboxes.com/smfforum/index.php?topic=126111.0

Go for it! 

Might be a stupid question, but if I am designing the PCB, I would just be adding an extra step by doing this method, no?

Yep.  You could just put the standard surface mount pads right on the board.

[OiMcCoy]

Awesome. I think I will go with this method then. Might take some practice with this method, but I am sure I will figure it out.

[garcho]

^ +1

That's great, so much talk has been had about how THT FETs are expensive or no longer available, yet SMD is plentiful, cheap, and really, not that hard to solder by hand, within reason. You should post a github link or something when you're done, help the diysb community with more SMT projects. I think the more people see, the less afraid they'll be to try.

[Mark Hammer]

Note that the JFETs used on the OS are simply being used as voltage-controlled resistors, making their potential gain moot.

Many of the compressors we are all familiar with use variable gain of some kind.  The OS is different in that it uses a fixed gain stage, which drives the FET gate, in addition to feeding the audio output.  The FET serves as one leg of an electronic attenuator, formed by the 82k input resistor and the drain-source resistance of the FET.

I've found it useful to make the gain of the op-amp stage variable in order to attain various degrees of light or heavier squish.  The stock circuit provides a fixed gain of 23x in the op-amp stage.  Take the  220k feedback resistor out.  Take a 50k linear pot and connect the pot wiper to the inverting pin of the op-amp.  Now attach a 180k fixed resistor to one of the outside lugs of that pot and connect the other end of the 180k resistor to the op-amp output.  You now have a feedback resistance that can be varied from 180k to 230k, depending on the pot setting.

To the other outside lug of the pot, attach a 6k8 fixed resistor, and solder the free end of the 6k8 to the 4u7 capacitor, replacing the 10k that used to be there.

The op-amp stage now has a variable gain that will go from a low of 4.2x to a high of 34.8x.  This should be a wide-enough range of possible gains to get you acceptable compression when feeding it line level or weak mic signals.  Naturally, if the gain of the op-amp is increased, the volume would need to be turned down.

[11-90-an]

You should probably check out GGBB's Orange Smoothie...

[PRR]

The original charm of the OS is that it used all easy-to-get parts. 40+ years on, if 2N5457 and '4558 are frustrating you, there may be better choices. Merlin and Reckless have each published their new takes on the topic. THAT Corp has a body of literature.

[ElectricDruid]

No-one would miss the '4558 in an OS. It's not a circuit where the op-amp is a key part of the sound. You could use pretty much anything within reason. Certainly TL072 is a reasonable substitution, and probably an improvement from a noise point of view.

[OiMcCoy]

Thanks for reaffirming my assumptions.

I am feeling much better about my chances of making a some awesome one knob compressors.


I am curious if anyone has opinions of the value changes suggested by BYOC for making it suited for bass.

[garcho]

http://www.thatcorp.com/datashts/dn125.pdf

^ There's a 1-knob job, too, from THAT, as PRR mentioned earlier. Even if you don't build that one, it might be worth reading through. I've built it, it works well.

[rockola]

2n5457's are hard to come by these days.

MMBF5457

Looks like even the MMBF5457 has now gone the way of the dodo; Mouser is saying they have no stock and there is a "Product Discontinuance Notification" from Onsemi with a last ship date in April last year.

I had a hunch this could happen and bought a roll of 1000 a while ago, just didn't think it would happen this soon. Maybe I can now retire on the 997 I have left Interestingly they have 2N5457 in stock, at a much higher price of course.

[EBK]

2n5457's are hard to come by these days.

MMBF5457

Looks like even the MMBF5457 has now gone the way of the dodo; Mouser is saying they have no stock and there is a "Product Discontinuance Notification" from Onsemi with a last ship date in April last year.

That's a little sad, but not unexpected.  I have faith that Steve@Smallbear grabbed a ton of them before they were discontinued.  I just ordered some from him, actually.

[Ben N]

2n5457's are hard to come by these days.

MMBF5457

Looks like even the MMBF5457 has now gone the way of the dodo; Mouser is saying they have no stock and there is a "Product Discontinuance Notification" from Onsemi with a last ship date in April last year.

That's a little sad, but not unexpected.  I have faith that Steve@Smallbear grabbed a ton of them before they were discontinued.  I just ordered some from him, actually.

Tayda, Digikey also have them.

[anotherjim]

You can sub in the MMBFJ201 can't you?