Sunn Model T pedal getting very very low sound

[Anonymous]

I’m going to go over the soldering on the components again, but I’m not seeing where I’m missing something. Any help would be appreciated.

[Billy]

Do you get effect but just at low volume

If that’s the case I’d start with reflowing the pot solder lugs especially volume lug 2 and treble lugs 2 and 3 some of the pot solder joints look like they may be dry

 

[Anonymous]

I did some resoldering,still not getting real loud…

 

The interference is because I have my soldering iron plugged in the same strip as the pedal.

 

https://youtube.com/shorts/VkwQmiK5Sig?feature=share

[Billy]

There are a few solder joints that visually look dry some also look like the solder hasn’t flowed properly

Before reflowing joints you’re better trying to find where your problem lies

Post your transistor voltages that may help narrow it down

Hopefully you got your J201s from Barry which will guarantee their good

In your video it doesn’t sound like you’re getting much drive did you have gain maxed?

 

[Anonymous]

I had everything maxed out. I biased the j201’s with the trim pots to come out. I didn’t get them from Barry and I’m thinking that might have been part of my mistake. I’ll order them tonight if you think that may fix the issue.

I tried a different solder with this build than my last. I was not a fan of it, so I’ll be switching back to what I’d been using on all my other builds.

[Billy]

May not be the transistors post the transistor voltages that may give us an idea

Some of your transistor solder joints do look as if they lack solder try reflowing those joints hold your iron on the joints for 4 seconds until you see a nice pool of solder making sure you get a good connection between transistor pin and solder pad allow each pin to cool before doing the next one

I’d wait until you know what it is before changing anything it could be something simple like a dry solder joint

Do you have an audio probe

[Cybercow]

TJ – From where did the J201s come?

[Anonymous]

@billy-I don’t have an audio probe yet. I saw some plans to build them online, I’ll probably do that this weekend. I’m still very new to all of this so I’m still getting up to speed.

@Cybercow – they’re bridgold j201’s from Amazon. They had good reviews. Next time I need some extra components I’m just going to order them from Barry with my pcb.

[Billy]

If you’ve got a multimeter take voltages on the transistor pins

Pinout like this

Here’s a PDF for an audio probe

https://drive.google.com/file/d/1T9OsJ0riQhm1QFWPfNQ5q5guikuFKDRN/view?usp=drivesdk

[Anonymous]

I built an audio probe and found some areas where there was some weak solder. I tried to reflow them and made some progress but still not sounding like it should.

I’m going to step away from that build for now and revisit it in the future. Thanks to you guys who’ve been helping me get it fixed.

[Anonymous]

Resurrecting this old post-

I was poking around with my audio probe and the c9 capacitor (270pf) is loud on one side and quiet on the other. I tried replacing it with a new one but the problem persists.

Any ideas?

[Barry]

We need the voltages for all J201 posted.

[Anonymous]

Hey guys. I’m having the same issue. Voltages as follows.
q1. D-4.71. S-.281. G-0

q2. D-4.71. S-.266. G-0

q3. D-4.71. S-.227. G-0.
q4. D-9.14. S- 5.25. G- 4.71

i biased towards the bottom end of the reccomended spectrum because it seemed to get a bit more volume.

[Author]

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