Author Topic: Strat Activator popping when turning pickups on (Read 516 times)

edwin · « **on:** April 23, 2016, 11:40:15 PM »

I just wired a Strat activator system into a friends guitar (it was the one listed in the Craigslist ad discussed in the Seen on... forum). Everything went as planned and it all worked as soon as I put it all together, with one slight hitch.

Instead of using a 5 way switch, my friend uses separate toggle switches for his pickups. So far so good, but when it goes from no pickups on to one or more pickups on, there's a pretty loud pop. If I switch pickups and keep one on at all times, no pops at all.

So, I'm wondering, do I need to add a pulldown resistor, as you do in an effects box, when it pops? Any other way to deal with this? I'm sure my friend will not like the popping.

Other than that, the system is dead quiet, which is very nice.

These pickups replaced an EMG system. It's like 3 octaves were added on the top end! The back pickup now totally nails a chicken pickin' Tele sound. Very clean, clear, and awesome to my ear. I hope he likes it. I think he might have been hoping for a bit more low mids, but hell, get a Les Paul, if that's what you are going for!

Actually, we are toying with the idea of having the bridge pickup routed for a humbucker, but I think the single coil sounds really cool right now, especially if you play with the filter. Do Alembic humbuckers do the coil split thing?

Now I want Alembic pickups in my Strat!

jazzyvee · « **Reply #1 on:** April 24, 2016, 05:55:35 AM »

Hi Edwin, I have a strat with at the activator pickups and electronics but use a blade switch and that works fine and no clicking between pickups but that could be because there is no off position. I'm considering doing a modification to my Orion guitar which involves OFF/ON switching.
Alembic don't have hum buckers they are all single coil hum cancelling pickups in the activators and non series instruments even the hum bucker sized ones (HG) only the casing is different.
My mod to my Orion involves using a pair of str pickups in the bridge and a pair at the neck to replace the existing hum bucker sized HG pickups. Mica is hoping to get some time soon with Ron to sort me out a schematic diagram for getting individual pickup switching for off/on or off/on/bright depending on what Ron comes up with. I'm hoping I don't get that click as at the moment the switching on my orion is silent.

edwin · « **Reply #2 on:** April 24, 2016, 09:44:34 AM »

I'm pretty sure that a blade switch would fix it, but it also limits the pickup combinations.

jazzyvee · « **Reply #3 on:** April 24, 2016, 11:59:29 AM »

I think what you are doing there is similar to the pickups switching setup for a Tribute guitar apart from it uses off/on/bright and not off on.

edwin · « **Reply #4 on:** April 24, 2016, 12:13:01 PM »

More or less. I'm wondering if the Tribute has the pulldown resistor built in and if so, what value it might be.

Or maybe there's an issue with the existing electronics.

lbpesq · « **Reply #5 on:** April 24, 2016, 01:27:23 PM »

Tributes and Furthers have a separate filter for each pickup. The Strat set has a single filter shared by all three pickups. I would expect this makes a difference in the wiring. (As an aside, I've found that adding a Q to the Strat set is an excellent mod. Not only does it add flexibility, it fills the third control hole in the standard Strat pickguard. $50 and easy to wire in).

Bill, tgo

edwin · « **Reply #6 on:** April 24, 2016, 01:44:56 PM »

Thanks, Bill, that explains it! Each pickup is separately buffered, so that gets rid of any popping issues. I'm sure a pulldown resistor would take care of it, I just don't have any ideas about how to calculate the proper value. I guess I'll google it. Anyone know what the impedance of these pickups is?

That black switch at the end is the Q switch. Thankfully, the original hole was pretty small, so it fit more or less perfectly. It could use an extra washer, but it's good for now.

edwin · « **Reply #7 on:** April 24, 2016, 03:18:50 PM »

Well, he picked it up and he loved it!

I'll deal with the popping issue later this week.

It does sound awesome through the Sarno CTP->McIntosh MC2105->JBL K120 rig.

elwoodblue · « **Reply #8 on:** April 24, 2016, 07:06:03 PM »

I measured two pickups with my cheap multimeter.
DCr reads 6.8 and 7.1 ohms. (gold logo pups)

elwoodblue · « **Reply #9 on:** April 24, 2016, 07:33:02 PM »

I started to dig a little as I'll probably come across the same issue as I install some activators.

I'm going to have to re-read this article. I'm
pretty convinced this was ghost written by Forest.

Cletus even gets a mention about halfway through!!

http://www.mrblackpedals.com/blogs/straight-jive/6629778-what-really-causes-switch-pop

edwin · « **Reply #10 on:** April 25, 2016, 01:18:27 PM »

I just got off the phone with Ron.

Yes, a resistor across the input will get rid off the pops, with the amount of attenuation dependent on the value of the resistor. Anywhere from 30k to 100k should work well, it's not critical, but the lower the value, the more the pops will be attenuated. If that doesn't cure it to satisfactory levels, a 20-22mfd cap can be added in series to the input to the preamp.

Apparently, the problem is that the bias current of the preamp flows through the pickup coils, so it needs somewhere to go during the switching transition from no pickups to pickups and vice versa. A blade switch renders it not a problem.

Easy fix.