J-Retro "knob wobble" - please help

TimBosby · #1 12-06-2010, 07:21 AM

So-

I recently bought a used J-Retro, and it sounded great, but then I stupidly started tinkering with it due to a "knob wobble" problem I was having. Basically, the upper knobs on the stacks seemed to "dip" slightly when turned (in other words, they didn't rotate evenly.) Furthermore, the upper CENTER knob (push pull) seemed wobbly, like it might move on its own if the bass was moved around on stage too much. I stupidly took a pliers to it to try to straighten the pots, and ended up breaking it. Sad story here:

FS: John East J-Retro drop-in jazz-plate preamp - CHEAP - $100 shipped

So I figured maybe the problem was that it was used. I bought a brand NEW J-Retro from Bestbassgear for $300 (very expensive in my eyes but I've read nothing but good reviews about them) and it has the same problem! It would be a 15% restocking fee plus shipping to return it, so I don't even know if it's worth it. I very much DO want to use this preamp but the knob wobble drives me nuts. It's my biggest pet peeve with bass controls. Any way to fix it without breaking it? Please help!

scotch · #2 12-06-2010, 07:39 AM

Quote:

Originally Posted by TimBosby

So-

I recently bought a used J-Retro, and it sounded great, but then I stupidly started tinkering with it due to a "knob wobble" problem I was having. Basically, the upper knobs on the stacks seemed to "dip" slightly when turned (in other words, they didn't rotate evenly.) Furthermore, the upper CENTER knob (push pull) seemed wobbly, like it might move on its own if the bass was moved around on stage too much. I stupidly took a pliers to it to try to straighten the pots, and ended up breaking it. Sad story here:

FS: John East J-Retro drop-in jazz-plate preamp - CHEAP - $100 shipped

So I figured maybe the problem was that it was used. I bought a brand NEW J-Retro from Bestbassgear for $300 (very expensive in my eyes but I've read nothing but good reviews about them) and it has the same problem! It would be a 15% restocking fee plus shipping to return it, so I don't even know if it's worth it. I very much DO want to use this preamp but the knob wobble drives me nuts. It's my biggest pet peeve with bass controls. Any way to fix it without breaking it? Please help!

Not sure if this is the issue, but it is always good to leave a little bit of clearance between stack knobs.

Even if the pot shaft is 100% straight & true, it's very easy to skew the knob when tightening the set screw. How severe is the knob-wobble? Are we talking a few degrees where you can only tell if you look very closely, or is it making more than an 1/8th inch of travel at any one point?

**RaginRog** · #3 12-06-2010, 07:57 AM

He'll reply to your email within 24 hours...ask for his advice, and let us know what he says.

john_east_uk@btinternet.com

or

John.East@which.net

TimBosby · #4 12-06-2010, 09:46 AM

Yeah John's great, he helped me with a problem even before I was a customer of his. I'll e-mail him later today.
It appears this "issue" is the case on all John East preamps, though, since I had it on both a brand new one as well as a used one. Can anyone else verify this?

TimBosby · #5 12-06-2010, 11:36 AM

It's not that extreme but I expected even rotation from such an expensive preamp.

I'm more concerned about the middle top knob feeling very loose.

The other two (first and third top knobs) just dip slightly, but they feel secure.

Quote:

Originally Posted by scotch

Not sure if this is the issue, but it is always good to leave a little bit of clearance between stack knobs.

Even if the pot shaft is 100% straight & true, it's very easy to skew the knob when tightening the set screw. How severe is the knob-wobble? Are we talking a few degrees where you can only tell if you look very closely, or is it making more than an 1/8th inch of travel at any one point?

**RaginRog** · #6 12-06-2010, 11:49 AM

Quote:

Originally Posted by TimBosby

It's not that extreme but I expected even rotation from such an expensive preamp.

I'm more concerned about the middle top knob feeling very loose.

The other two (first and third top knobs) just dip slightly, but they feel secure.

Shoot me a PM and let me know what he says/recommends because my upper knob gets hung up on the lower one a bit. It is a bit annoying, especially for the cost.

scotch · #7 12-06-2010, 11:50 AM

Wow, are they using odd pot shafts?

TimBosby · #8 12-06-2010, 12:00 PM

Not sure.
I emailed John.
he's always been great so hopefully he can help.
these preamps are VERY expensive compared to an Audere for example but I'm hoping the customer service can make up the difference.

**RaginRog** · #9 12-06-2010, 03:25 PM

Quote:

Originally Posted by scotch

Wow, are they using odd pot shafts?

Well, he uses a split shaft on some of the concentric set ups...personally, I prefer solid shafts if you're using knobs that require tigthening via a screw driver or allen key. He provides a brass sleeve to go over the split shaft, but it still has a little give.

scotch · #10 12-06-2010, 03:32 PM

Quote:

Originally Posted by RaginRog

Well, he uses a split shaft on some of the concentric set ups...personally, I prefer solid shafts if you're using knobs that require tigthening via a screw driver or allen key. He provides a brass sleeve to go over the split shaft, but it still has a little give.

Gotcha. I also prefer solid shafts, but I keep a small stock of the brass sleeves handy if I'm stuck with a split shaft. They're a little fidgety to work with, but help with set-screw knobs.

mech · #11 12-06-2010, 04:56 PM

Quote:

Originally Posted by TimBosby

"knob wobble" problem....

With any set screw knob, the hole in the knob has to be slightly larger than the shaft of the pot just so it'll go on. When the set screw is tightened, the knob is pushed away from the shaft by the screw and all the "slack" shows up on the screw side. The knob and shaft are no longer concentric and this is what causes the knob to be eccentric and appear to wobble.

You can minimize the wobble by wrapping thin tape around the shaft to where the knob will barely slide on, then tighten the set screw.

Split shafts should always get sleeved but there will always be some wobble with set screw knobs.

mech

TimBosby · #12 12-06-2010, 06:23 PM

John told me that the push-pull pots have always been loose in the 12 years he's been using ALPS pots.

As far as the other knobs dipping/not rotating evenly he pretty much said what was summed up in this thread and offered to send me 3 upper knobs. I don't know what I'm going to do yet. For $300 it seems like I shouldn't have needed to even bring this issue up. At the same time, something so frivolous shouldn't bother me (but it does)
Furthermore, I've heard these preamps are amazing, tonally diverse - but...I'm not sure I need that for this bass, and an Audere would serve me just as well.

**RaginRog** · #13 12-06-2010, 06:54 PM

Quote:

Originally Posted by scotch

Gotcha. I also prefer solid shafts, but I keep a small stock of the brass sleeves handy if I'm stuck with a split shaft. They're a little fidgety to work with, but help with set-screw knobs.

Where do you buy brass sleeves? When I had a couple, I actually used one, then split a sleeve and put it over an existing sleeve (doubled the thickness), and it really kept the knob tight.

TimBosby · #14 12-06-2010, 07:00 PM

Quote:

Originally Posted by RaginRog

Where do you buy brass sleeves? When I had a couple, I actually used one, then split a sleeve and put it over an existing sleeve (doubled the thickness), and it really kept the knob tight.

I've tried those same tricks with brass sleeves, bits of drinking straw, electrical tape, etc, never quite got it to work out that well.

scotch · #15 12-06-2010, 07:51 PM

Quote:

Originally Posted by RaginRog

Where do you buy brass sleeves? When I had a couple, I actually used one, then split a sleeve and put it over an existing sleeve (doubled the thickness), and it really kept the knob tight.

near bottom of page...

http://stanhinesleypickups.com/passive_controls.htm

TimBosby · #16 12-07-2010, 05:50 AM

The J-Retro should come with brass sleeves, but I haven't bothered dismantling it yet, in case I decide to return it.

gerrywarwick · #17 12-14-2010, 07:35 AM

The knobs on my Marcus Retro work perfectly. When I changed the bottom knobs to black, I noticed the shafts had sleeves. Good thing because the replacement knobs didn't come with any. The Marcus retro is high quality top to bottom. No wobble either. I was going to get one for my Roadworn but I think I'll try the Audere and compare.