Bearhug Compressor - schematic, demo, layouts, & forthcoming 1776 PCB!

[midwayfair]

I'm using the 2.5 schematic in Josh's build document but a couple numbers changed between versions so some older posts might not be the same.

[solderfumes]

Okay, I see a v2.1 schematic on the 1776 Effects webpage (I assume that's the Josh you're referring to), and that's the one I'm using.  To confirm, the mod you suggested a few posts ago about adding a 33k resistor in series with C5: that refers to the capacitor that goes from the output of the MOSFET booster stage into the base of the MPSA18, is that correct?

I traced most of my distortion problem to an out-of-spec 2N5457 based on one of the Bearhug threads on the Madbean forum, so replacing that made the compression a lot more reasonable and usable.  The circuit still clips when I use my P90-equipped guitar, but the same is true if I disconnect the sidechain from the source of Q1 and turn the circuit into a straight MOSFET Booster, so I think that's just something I'll have to live with.

[midwayfair]

Okay, I see a v2.1 schematic on the 1776 Effects webpage (I assume that's the Josh you're referring to), and that's the one I'm using.  To confirm, the mod you suggested a few posts ago about adding a 33k resistor in series with C5: that refers to the capacitor that goes from the output of the MOSFET booster stage into the base of the MPSA18, is that correct?

I traced most of my distortion problem to an out-of-spec 2N5457 based on one of the Bearhug threads on the Madbean forum, so replacing that made the compression a lot more reasonable and usable.  The circuit still clips when I use my P90-equipped guitar, but the same is true if I disconnect the sidechain from the source of Q1 and turn the circuit into a straight MOSFET Booster, so I think that's just something I'll have to live with.

Yes, that's the correct capacitor.

In your case running it on 18V might actually be helpful, since you know it's a circuit headroom issue. Don't know what you boxed it in but a 1590B could fit a charge pump. Test it first, though, no sense wasting the parts if it doesn't help.

[solderfumes]

I'm thinking of building an all-bells-and-whistles version so it'll definitely be going in to a 1590B, and will try that out!

If I'm doing that, I might also try an alternative method for biasing Q3.  I saw you suggest that this would be possible either in this thread or in another forum if you had a negative power source, and if I'm throwing a charge pump in there, that could work.  I thought I had an idea of how to do it, but am realizing it's maybe not as simple as I thought.  Do you have a brief description of how this would work?

[rankot]

I traced most of my distortion problem to an out-of-spec 2N5457 based on one of the Bearhug threads on the Madbean forum, so replacing that made the compression a lot more reasonable and usable.

Could you please give us more details on what specs 2N5457 has to have for this circuit, since I have built Bearhug a long ago, but I have never be so happy with the sound. I bought 2N5457 from China, maybe they are out of specs, too?

[midwayfair]

I traced most of my distortion problem to an out-of-spec 2N5457 based on one of the Bearhug threads on the Madbean forum, so replacing that made the compression a lot more reasonable and usable.

Could you please give us more details on what specs 2N5457 has to have for this circuit, since I have built Bearhug a long ago, but I have never be so happy with the sound. I bought 2N5457 from China, maybe they are out of specs, too?

Measure the resistance, it should be about 300 ohms, within about 20%. Most are.

Being out of spec doesn't change the overall sound much if at all, it just affects the compression range.

[rankot]

Those 2N5457 I have have 8.7k resistance between gate and source or gate or drain, but drain-source resistance is rising whenever I try to measure it with DMM - starts from some 110 ohm and then rise and rise and rise...

[stan-thomas]

The 100K trimpot in the 2.1 version is for blend?

[midwayfair]

The 100K trimpot in the 2.1 version is for blend?

No, it's a bias for Q1. There is no blend control.

[stan-thomas]

No, it's a bias for Q1. There is no blend control.

Since this is an amazingly low part count compressor, while placing order it would be convenient for me to order the parts for the blend. If there is no phase change, can a simple blend like this be added? Moreover it would be a comfortable for a 1590B.
http://effectslayouts.blogspot.in/2015/01/simple-fet-blender.html

Would it be useful?

[slackshampoo]

Anyone still have this schematic and care to share? I've looked around and only found the same dead links.

[midwayfair]

Anyone still have this schematic and care to share? I've looked around and only found the same dead links.

https://cdn.shopify.com/s/files/1/0022/3952/9069/files/Bear-Hug-V2-1.pdf?16138734983046189115

[slackshampoo]

Awesome! Thanks a bunch