Author Topic: Shielding saga (Read 1224 times)

edwin · « **on:** February 11, 2016, 12:12:53 AM »

So, I've been working on the fact that my Starfire is a bit noisy. It's been a problem with directional noise. In the last 4 hours I have discovered something.

Carbon shielding paint isn't worth squat.

I had assumed (yeah, we know how that goes) that applying as much of this stuff as I could in the cavity would give me at least a bit of protection. But, I finally decided to see what would happen if I created a little box out of some sheet copper I have lying around and close off some of the areas where I couldn't reach with the paint. I did that. A bit of a change. Then, I decided to check continuity throughout the cavity. Nada. The paint was not conducting anything. So, I cut up some more pieces of copper and added them to the other areas which had previously been only covered by paint. I'm starting to hear a real difference. There's still some noise, but it's cut by at least 15-20db. I still have some areas to cover and I'm going to have to come up with a good strategy as to how to reach them (the door in the back is frankly too small. I should have been far more adamant in designating the size cutout I wanted back when I had it done in 1996. Thing is, the guy did a lovely job. Just too small.). I've spent the last 18 years thinking I had at least a minimal amount of shielding in there when I in fact had none.

I had to remove the pickup selector switch, since it's so far toward the horn and it's just hard to get things arranged in that part of the cavity, but I think if I spend some more time on it, I should be able to get it together. Maybe I can even go back to the old pickups!

I really get why Alembic uses the silver stuff. It works.

Live and learn.

jacko · « **Reply #1 on:** February 11, 2016, 07:19:56 AM »

Could you not fill the instrument with the silver shielding paint then slosh it around a bit to get full coverage?

Graeme

lbpesq · « **Reply #2 on:** February 11, 2016, 08:44:25 AM »

Edwin:

You might want to try some shielding tape. I've used it often with excellent results.

http://www.stewmac.com/Pickups_and_Electronics/Shielding/Conductive_Copper_Tape.html

Bill, tgo

edwin · « **Reply #3 on:** February 11, 2016, 09:17:21 AM »

I've tried shielding tape and the cover of the access door is covered in shielding tape. The problem is getting complete coverage without making a mess as the stuff is pretty thin and hard to control while applying it through the smallish hole. I'm sure someone with better skills than me could do it, but copper sheeting seemed easier.

I like Graeme's idea!

Obviously the best way to go would be to cut a much bigger door and then apply the shielding tape or silver paint, as in Keith's bass.

lbpesq · « **Reply #4 on:** February 11, 2016, 11:05:38 AM »

Edwin, maybe you need to find one of those people who make ships in a bottle.

Bill, tgo

edwin · « **Reply #5 on:** February 11, 2016, 11:15:42 AM »

That's better than becoming one of those people who make ships in a bottle!

At this point, I think I'm going to bring it with me to SF at the beginning of March and drop it off for some mothership love.

lbpesq · « **Reply #6 on:** February 11, 2016, 11:43:50 AM »

Sounds like a good idea. Hope we can get that mini-gathering together while you're in town.

Bill, tgo

ed_zeppelin · « **Reply #7 on:** February 11, 2016, 12:23:02 PM »

quote:That's better than becoming one of those people who make ships in a bottle!

Or you can open a bottle with those people and become ship faced!

gtrguy · « **Reply #8 on:** February 11, 2016, 08:00:14 PM »

If you use multiple bits of copper; Be sure to solder the copper together with solder dabs to get it to all conduct.

I don't like copper with tape backing, as it interferes with positioning the sheets.

edwin · « **Reply #9 on:** February 14, 2016, 11:01:23 AM »

Report from last night's gig:

First off, there were various issues of humming and buzzing from the house PA. The venue is about a 600 capacity theater. (I bring a splitter snake and then run in ear monitors from my recording rig, 2 Metric Halo ULN-8s and an RME Octamic D. It allows me to scrutinize all the channels as well as create great in ear mixes.). I am always a little paranoid that my split and recording rig will create issues, but as we went through them, they all proved to be bad mic cables, problems with the FOH console, etc.

Weirdly, I had a hum issue with my DS5-R and F2-B in my rack. I didn't really have time to troubleshoot it, so I switched out to the little blue box and used no preamp beyond my Felix, which is also the DI. From there, the signal went to a Showman/Sunn 200S rig with an RE20 on one of the JBLs. Sounded good in the soundcheck and the directional noise was almost absent. At least, the FOH guy never commented on it at all. I still had noise when I got close to my computer/interfaces, but that usually happens.

D'oh moment of the night: I couldn't get a good signal from the RE20 off my amp. After the set, I noticed that the send had gotten misrouted during the opening band's set. They also bumped a switch that put one pickup out of phase with the other, but that was easily trouble shot (shooted?). Once that got sorted out for the second set, the tone was great.

So, I think if I can close up a few more gaps in the shielding, I may not have to spring for the electronics upgrade. Part of me still wants to have Ron and the crew go through everything, and I'm sure he'd make it even quieter, but finances being what they are.... I also have a gig in May covering 5/14/1974, and it would be best to have this bass.

ed_zeppelin · « **Reply #10 on:** February 14, 2016, 12:55:17 PM »

I found this page with the set list. (What is WRS?)

Scroll down to the comments to read Ripplerous' account of the %#?&@ who threw a bottle that hit Bobby in the face - and the band's magnificent reaction.

Here's a great HD pic of Bobby and Phil (from 6/8/74), with a fantastic view of The Godfather and the Wall.

rv_bass · « **Reply #11 on:** February 14, 2016, 01:30:49 PM »

WRS = Weather Report Suite

edwin · « **Reply #12 on:** February 14, 2016, 03:41:30 PM »

Weather Report Suite, aka Prelude, Part I, and Let It Grow.

edwin · « **Reply #13 on:** February 22, 2016, 02:56:40 PM »

OK, surgery has started for the new shielding job.

StephenR · « **Reply #14 on:** February 22, 2016, 04:03:00 PM »

When I was visiting Alembic last week Susan commented about how ridiculously expensive the silver paint they use to shield the cavity is. Mica and I both got a laugh out of Graeme's suggestion that you fill the cavity with it and slosh it around. Good idea in theory but that would make for one expensive shielding job.

Good luck with the surgery!