Double Bass Loud rattle with Genz Benz Shuttle 3.0-10T

[DoubleMIDI]

About a week ago I took my bass with my Genz Benz Shuttle 3.0-10T Combo to a rehearsal by bicycle and trailer (it is a really large bicycle trailer where the body of the bass lays mostly inside) about 6 km away from home.

When I arrived I saw that my endpin was missing (silly me, I forgot to fasten the screw), went home again hoping to find the endpin on the way (I didn‘t) and got something I could use for the rehearsal instead. So don‘t talk bad about endpins that cannot be removed from the endpin collar …
I made a new one from a steel rod I already had the next day.
But that’s not the point here.

When I got back I needed to turn up my amp a lot because three percussionists (Cuban and salsa stuff) got really loud and I (and mostly the percussionist in front of it) heard a loud rattling with any note, but loudest with the open G string.
BTW, the amp was in a cajon bag laying on its back when transported in the front part of the trailer.

After the rehearsal I went back the same way with the trailer. At home I heard a bit of rattling but not comparable with what I heard in the rehearsal. No rattling with a different speaker (Genz Benz Focus FCS-112). I thought something might be loose or some part got inside the cab, so I removed the grill (don‘t remove the screws, you might make it even more difficult to find the holes later), looked for a broken or loose membrane (everything was OK).
Then I unscrewed the driver to look for any loose part inside, but couldn‘t find anything loose.
I had no idea what could have rattled and where.

Then I thought the capacitor in the tweeter cable (sealed in shrink tube) might have been in contact with the woofer enclosure. Just a guess, I couldn‘t proof it. I had some 5 mm thick rubber foam that I wrapped around the capacitor, fixated at both ends with a tight thread loop and built the whole thing back together. The concert (again transporting the same way with the bicycle trailer) went without any problems, but I‘m still not completely sure that this caused the rattling.

I just thought I tell you what happened and what I did.
I never had this problem before, but thought that my modification might be a good idea to do. Maybe other owners of that amp might want to do the same to avoid that potential problem. Might apply to the -8T cab too.
I would be interested if anybody had this or similar problems with that type of amp.

 

[jj.833]

That's a very nice story, somehow reminds me of early 20th century life stories of smart guys like Alan Turing.

I have nothing to share except that I though the capacitors should generally not be wrapped in anything for cooling. But since you write it was in a shrink tube from the factory, I guess I thought wrong.

Everybody going for double bass gigs on bicycle is a real real hero!

 

[Ric Vice]

After the rehearsal I went back the same way with the trailer. At home I heard a bit of rattling but not comparable with what I heard in the rehearsal. No rattling with a different speaker (Genz Benz Focus FCS-112). I thought something might be loose or some part got inside the cab, so I removed the grill (don‘t remove the screws, you might make it even more difficult to find the holes later), looked for a broken or loose membrane (everything was OK).
Then I unscrewed the driver to look for any loose part inside, but couldn‘t find anything loose.
I had no idea what could have rattled and where.

Then I thought the capacitor in the tweeter cable (sealed in shrink tube) might have been in contact with the woofer enclosure. Just a guess, I couldn‘t proof it. I had some 5 mm thick rubber foam that I wrapped around the capacitor, fixated at both ends with a tight thread loop and built the whole thing back together. The concert (again transporting the same way with the bicycle trailer) went without any problems, but I‘m still not completely sure that this caused the rattling.

I just thought I tell you what happened and what I did.
I never had this problem before, but thought that my modification might be a good idea to do. Maybe other owners of that amp might want to do the same to avoid that potential problem. Might apply to the -8T cab too.
I would be interested if anybody had this or similar problems with that type of amp.

Since the Genz Ben Shuttles are now such prized commodities. I’m just glad you were able to diagnose and “fix” the issue.
The college where I used to work at their summer jazz camp, has a Genz Benz Shuttle 8T and as the years progress that amp
has developed speaker and cabinet noises from constant use in Jazz performance program. It’s a shame really, but the sad reality
is that over time, amps that aren’t well treated and serviced when they are in need of repair will eventually develop rattles
and noise, no matterp how well built they were when new. Since you know how to service your Genz Benz and take care of it
your’s will hopefully see many more years of making music.

 

[longfinger]

Just a thought, end pins that are loose or ill fitting also cause rattles. Perhaps the home made endpin was the source of the rattle and not the combo? Did the combo rattle with a bass guitar? Did the upright rattle acoustically?

Perhaps the combo fix and the rattle stop was just coincidence?

 

[DoubleMIDI]

Just a thought, end pins that are loose or ill fitting also cause rattles. Perhaps the home made endpin was the source of the rattle and not the combo? Did the combo rattle with a bass guitar? Did the upright rattle acoustically?

Perhaps the combo fix and the rattle stop was just coincidence?

Partly possible. But it was not the bass.
The bad replacement endpin was very short and well fixated (at the bass, but slipping on the floor so I needed a carpet). But since back at home the speaker of the -10T rattled and the Focus FCS-112 when connected to the Shuttle instead didn‘t, showed me clearly that it was the -10T.

My problem was time. The rehearsal where everything went bad (even a flat tire because of a defective inner tube that was OK the day before) was on Thursday evening and the gig was on Saturday, so I had one and a half day to make the endpin and trying to repair the -10T (otherwise I had to take the Focus and couldn‘t use the bike (no bag for the Focus).

I searched the evening how much a new endpin only might cost, but found out that new endpins almost always come with the endpin collar that I didn‘t need. The ones without are rather expensive (for me).
The cheap ones at Thomann would have been risky to arrive in time and had no dents.
So I decided to make one myself from the steel rod I already had from making the short badly made endpin. That was the cheapest and safest option.
The endpin took me four hours filing the tip and the dents for the fixation screw so that the Wolf endpin assembly fit well and the spike would also work on a wooden floor. Could be a bit nicer but is fully working. If I would have had more time I might have tried one made of brass.

Four hours were already gone, so not much time left for the speaker diagnosis and fixing.
And I wanted to be ready on Friday evening to have some spare time on Saturday morning if something went wrong.

Of course the backup was get a carpet, use the bad existing endpin, use the other cab and go by car. So I could stay a bit calmer making the stuff.

The rattle was also very different from a loose tuner screw or something similar and closely related to the master volume setting. So clearly not the bass and not the amp because no rattling with a different cab.

Next week I need both cabs with my EUB and it will get loud.
I might bring the combo with the -10T for the rehearsal two days before and turn it up to check it again.

BTW, the only place to check the cab quickly was to place it on the balcony, inside there is always something that vibrates sympathetically at that output volume.

Using the bike was only possible because I found a way that was very flat. No supporting motors, only muscle power.
The one part where I had to go up was very exhausting and the way back went very slightly up the whole time and was not as nice to go (and also after the gig) as the way to the place before, which was really easy.

 

[Erik Turkman]

If you need service for Genz Benz gear, Andy Field, who was part of the original GB team and who now designs for Mesa Boogie, provides service for GB amps. He is an active participant on TalkBass and goes by @agedhorse.

 

[DoubleMIDI]

If you need service for Genz Benz gear, Andy Field, who was part of the original GB team and who now designs for Mesa Boogie, provides service for GB amps. He is an active participant on TalkBass and goes by @agedhorse.

Thanks for the hint.
You couldn’t know that I have known that and I would have asked him, but I needed a quick solution for the next day (as a fallback I could have used a different cab and did know it was the cab and not the amp), so I checked it myself first, had an idea what might have been happened, put foam around the potential culprit and the last two gigs went really well at a rather high volume.
Time was really limited (about two hours) since on the same day I needed to make me a new endpin because I lost mine during the bike ride the day before.

I know I can never be completely sure if this was the reason and solution, but I’m rather confident that it won’t happen again.

I would be happy if @agedhorse would give a comment. I just wanted to know if this ever happened to another Genz Benz Shuttle 3.0-10T user here on Talkbass first.