Median Compressor PCB - Available Now!

[jcpst]

When I did a bit of searching on the T7, it sounds like the processor has been changed over time with varying levels of reliability.

I picked up my 2N5457s from Stomp Box Parts, and they seemed legit based on my tester and it working as expected. This is the one I ended up buying:

https://www.amazon.com/gp/aw/d/B01MS1FOYM

 

[ninjagrips]

Thanks, I might give that tester a try.

I did quickly hook up some jacks and a switch to the pedal, and tried it out for a minute.

It seems to be working, and I have the trim pot set roughly in the middle of its range. Still not quite sure where to set that.

I guess the transistors are fine, because the circuit seems to be working. No idea if they meet the specs written on the build guide, though I installed some sockets so I can swap them out if I need to.

Currently using TL072CP opamps.

So, for now, I suppose I'll drill the enclosure and install everything and play with it some more.

 

[Brett]

I just don't know how to properly test them without the pricey Peak DCA Meters

There's plenty of information here and elsewhere about testing JFETs without the need to purchase expensive equipment. All you need is a few components and a DMM. Search for the ROG JFET testing method.

 

[jcpst]

Found this

Post in thread 'JFET Shootout'
https://forum.pedalpcb.com/threads/jfet-shootout.13363/post-178707

 

[ninjagrips]

Thanks y’all I’ll look at those threads. Here’s a few pics of the build so far.

 

[lowpitch]

Digging that cream/turquoise combo

 

[Feral Feline]

Thanks y’all I’ll look at those threads. Here’s a few pics of the build so far.
View attachment 84065View attachment 84066View attachment 84067

Looking forward to the Build Report!

 

[zeropluszero]

Any idea what I could use in place of bat43? I have 41, 46, 4148, 5817, 4001, 914
Or should I make the effort to find 43?

 

[Feral Feline]

What do the datasheets say?

Following are Google hits from Mouser...


BAT41
STMicroelectronics: ...Schottky ; Voltage - DC Reverse (Vr) (Max). 100 V ; Current - Average Rectified (Io). 100mA ; Voltage - Forward (Vf) (Max) @ If. 450 mV @ 1 mA.
Vishay: Specifications ; Vrrm - Repetitive Reverse Voltage: 100 V ; Vf - Forward Voltage: 1 V ; Ifsm - Forward Surge Current: 750 mA ; Ir - Reverse Current: 100 nA.

BAT43
STM: Specifications ; Vf - Forward Voltage: 450 mV ; Ifsm - Forward Surge Current: 4 A ; Ir - Reverse Current: 500 nA ; Minimum Operating Temperature: - 65 C.

BAT46
STM: Specifications ; Ifsm - Forward Surge Current: 750 mA ; Ir - Reverse Current: 5 uA ; Minimum Operating Temperature: - 65 C ; Maximum Operating Temperature: + 125 C.


Check out the specs of the other ones you have.

I'm guessing that, like clipping, fV is important — but Reverse Current and/or other specs may be important, too, in this particular circuit.
WHAT ARE THE DIODES DOING, what's their job?
Try to match the spec of the BAT43 as much as possible, then socket and see if it works. Once working, remove sockets or solder diodes into the sockets.

 

[zeropluszero]

I don't know enough to say what they're doing. Given they're in the path I assume some sort of clipping.
I guess I can socket when I get the rest of the parts, see how it sounds. I just can't see bat43 available at any of my usual haunts.