Ampeg tone stack modification

[Hangman]

Ok! I have some boards ready. I am curious however if those of you interested in them would care to weigh in on something.

So the original PEC tone stack was completely encased in some sort of resin or compound. These new boards do have exposed leads and exposed solder connections. if one of those exposed points shorted to ground the whole circuit would not perform correctly. I think it wouldn't take much effort on the part of the one installing it to prevent this from happening. and certainly less effort that installing each component one by one as I did in the original blog post. but none the less...
I am considering putting a silicone conformal coating on the boards to prevent this from happening.

it would basically seal the components into the module. The coating can be removed of course, but it would act as a barrier.

thoughts?

[itsonlyadam]

I say, as long as these have high quality components, then go for the coating! I wouldn't mind a little extra security when lugging my Ampegs around! Just my 2 cents!

[Hangman]

I designed them to fit Mallory 150s for the .0047uf , .01uf and .001uf

The 470pf is a silver mica, and the resistors are both carbon film, I could use metal film if anyone objects to the use of carbon film, but I thought it would be a little closer to what Ampeg would have used.

how does that sound?

[Liquids]

It's been a while, but when I did a board from perf with exposed leads, I think it worked easily with plenty of room when fit from the back of the board instead of in front. It was probably smaller though--forgot how much space is available.

These new boards do have exposed leads and exposed solder connections. if one of those exposed points shorted to ground the whole circuit would not perform correctly. I think it wouldn't take much effort on the part of the one installing it to prevent this from happening. and certainly less effort that installing each component one by one as I did in the original blog post. but none the less...
I am considering putting a silicone conformal coating on the boards to prevent this from happening.

it would basically seal the components into the module. The coating can be removed of course, but it would act as a barrier.

thoughts?

[Hangman]

I think typically there is plenty of room on the back, and while these are considerably thicker than the original PEC chip, they would likely fit reasonably well between the pot and the board.

I think I tend to err on the side of caution, and make it harder to make a mistake. If I was installing every one myself, I wouldn't worry.

[Hangman]

Sorry for the poor lighting in the picture.
But here is a picture of the completed PEC6470000 replacement

[Liquids]

I like that, a lot!

I bet you'd make a ton of SVT players really happy if their tech's installed these and they didn't know, but they gave it a listen.

Some people might have vintage mojo when it comes to SVTs, but I imagine even an SVT would see an improvement if it had one of the old boards and this was replaced. You made it easy, too!

Every Ampeg with an EQ board should have one of these (or the like)!
If a person orders more than one - it's really interesting to mess with the treble values. I have mine permanently at 220pf/2.2n for a sweeter high end response, and it changes where the mid scoop falls. One could swap back and forth EASILY with two populated boards like this. Just 7 solder points to do/undo so long as your particular ampeg doesn't have low quality traces.

[Hangman]

Yes. I was actually going to offer a few different options for the capacitor values. some of the earlier ampeg amplifiers even used a .002/.02 combo for the bass, and a 500pf/.002 combo for treble.

So I thought I would offer that as an option, and I do like your suggestion of the 220pf/.0022uf combo too.

My thought is that I will use the conformal coating and then use some sort of color system to tell the difference between the different models.

for amps like the g12 or b25, there are separate modules for each channel. so you can replace them each with a different module, and get more tone shaping options from the amp.
kinda cool really.

I like that, a lot!

I bet you'd make a ton of SVT players really happy if their tech's installed these and they didn't know, but they gave it a listen.

Some people might have vintage mojo when it comes to SVTs, but I imagine even an SVT would see an improvement if it had one of the old boards and this was replaced. You made it easy, too!

Every Ampeg with an EQ board should have one of these (or the like)!
If a person orders more than one - it's really interesting to mess with the treble values. I have mine permanently at 220pf/2.2n for a sweeter high end response, and it changes where the mid scoop falls. One could swap back and forth EASILY with two populated boards like this. Just 7 solder points to do/undo so long as your particular ampeg doesn't have low quality traces.

---

Here is a picture of the module next to a module I pulled out of my GV-22.

The module I pulled from the GV-22 is labeled 1346850 CR-01. But it is identical to the PEC#6470000.

[syscokid]

I am so very interested in these modules...

[beedoola]

Hey Steve, are you offering etched PCBs of this module? Do you also happen to have extra components? Or at least the caps. Are the resistors 1/4w? If so, I probably have the values.