Help! Aguilar DB 359 Problems

[ajb]

Hey there everyone, I'm new to the talkbass community and need some input regarding a problem I had with my Aguilar DB 359 at band rehearsal on Saturday. bear with me, this may be a little long. Basically, the amp cut out on me about ten minutes into our first song. It didn't completely cut out, but there was a dramatic loss in volume that made the amp unuseable. The weird thing is that when I tried my amp at home afterwards, it worked perfectly. FYI I have a passive Fender jazz bass and I was plugged into the passive jack.

I called Aguilar and, although they're very nice and responsive guys, they weren't too helpful. Their tech guy told me that unless I could recreate the problem, neither they nor an authorized repair technician could fix it. Is this right? The tech guy also made some bizarre recommendations about recreating the problem, such as inserting a "chopstick" into the active input jack while playing in the passive jack and -- get this -- giving the amp a good smack. I did not do any of these things, of course, but I did try to recreate the problem at home by playing at different volumes, settings, etc.). I couldn't get the amp to cut out no matter how hard I tried. I have a gig coming up and I need the amp to work, period.

Some additional history that may be helpful: About two weeks ago I sent the amp in for warranty repairs for a problem I was having when I ran my bass through my Sadowsky preamp into the active jack. When I did this (which I rarely do because the Aggie is so rich on its own) I was getting an annoying static-like sound out of the speakers. That problem was diagnosed as "intermittent contacts in the passive jack switch," and as far as I know the problem was repaired (I ran my bass through the Sadowsky preamp after receiving the amp from the warranty repair people and it sounded fine). Whether the "intermittent contacts" problem is related to the drop in volume I experienced at band rehearsal, I don't know.

I would appreciate any insight you guys may have. I just cannot accept that there's no one who can figure out what went wrong unless I can recreate the problem (BTW I don't have an avatar or profile info because I'm a computer idiot and don't know how to do those things, so help in those areas would be appreciated as well).

 

[ajb]

Let me just add that I absolutely love this amp. For the brief period that it was working, it sounded amazing. Now, if I could only get the damn thing to work when I need it to.

 

[Nightbass]

I have a 359 and have also worked on a lot of electronic gear. A transient symptom such as the one you described is on of the most difficult to diagnose. It could literally be any one of 1000 things internal and even external to the amp.

Troubleshooting defective gear is easy when the problem is present. The techs at Aguilar were doing the best they can, giving you a couple of things to try that might help solve the mystery.

Since it might be jack-related, all I can say is that perhaps your 1/4" plugs are too small. I just got some Neutriks that are a much tighter fit than George L's, for example, meaning that the GL's are undersized!

 

[ajb]

Thank you Nightbass. This is interesting. My instrument and speaker cables are the cheapest part of my signal chain. I don't know much about instrument cables but I think am using a 1/4" plug (it's just a regular old instrument cable, several years old, not even sure what brand it is). I think I will buy some Neutriks and give them a try.

BTW, is there just one type of Neutrik instrument cable or are there several, i.e., which one should I buy?

 

[kjones]

You can go here:

Link Removed


He is a TBer, and I have had great service from him. You can specify Neutriks on the end (which I did as well). Great cables and prompt service at a reasonable price.

 

[Nightbass]

Yep, Bayou is exactly where I got my new cables. Highly recommended!

I think the deal with the input jacks is that when one or both is not being used (i.e., doesn't have a plug inserted into it), the jack is supposed to short that input to ground via a mechanical contact. This grounds the input to the tube preamp and keeps it quiet. But if the spring contacts of the jacks are bent or dirty, the shorting leg can be intermittent and cause the problem you are describing. So that is why they recommended poking the jack with a chopstick.

If you want to test it more, plug into the passive and gently wiggle the plug. See if you can induce noise. Then repeat the same with the active input. That might reveal something.

 

[ajb]

Thanks for the responses guys, I appreciate it. I actually tried wiggling the plug around in the jack but it didn't re-create the problem. I'm thinking it may not be a jack issue now but hell, I'm no expert. I'll try the Neutriks anyway.

This is really frustrating because I know what is going to happen: I am going to go to rehearsal this Saturday and the amp's going to crap out on me again (I know, I'm a real optimist). Then I won't be able to recreate it at home and no one will be able to diagnose the problem. This is kinda like that old Warner Bros. cartoon where the construction worker has a frog that sings and dances, but only when no one is looking.

 

[tombowlus]

This is kinda like that old Warner Bros. cartoon where the construction worker has a frog that sings and dances, but only when no one is looking.

You have a frog that sings and dances!?! Cool!

Actually, I am suspecting your cables as well. I've never experienced anything like this with my DB 359, but I am eager to hear if new cables clear it up for you.

Tom.

 

[ajb]

So I tried out the DB 359 this weekend once again at band rehearsal. This time the amp worked perfectly. I didn't change a thing, except we played in a different room (same building). I have never heard an amp sound this good. I am truly baffled by people who think the DB 359 isn't loud enough -- I ran mine through my GS 212 cab and with the master at three and the preamp gain at four I had volume and depth to spare. You really can't get a sense of how powerful this little brute is in your room. What sounds modest in my room sounds huge in a band setting.

I'm glad the amp worked out, but I still have a nagging concern about the amp cutting out on me last weekend. Could it have been something about the room we practiced in last week? I used the exact same cables this time and plugged in exactly the same way (although I did order brand new instrument and speaker cables from bayoucables just to be safe).

Anyone care to speculate (one more time) about what might have caused the drop in volume last week?

 

[Pickebass]

I had a similar problem with mine. Are all of your tubes OK? I had a situation where one of the tubes was going bad and eventually blew a fuse internally. At first the volume was getting lower, then it distorted, then I couldn't get any volume at all.

The bad tube had a purple color to it, instead of blue like the others. Everything was OK they one day it started with these problems. I contacted the folks at Aguilar and they replaced the fuse internally (which is covered by your warranty), and you have to buy a tube(s).


This is one of the best sounding amps around. The key to this amp is putting it with an efficient cab. It didn't work well with my Berg 310, but sounds great with my GS410. With the GS112s, it's OK until it gets really loud

 

[foderaman]

You may want to check your speaker cable.If it is a 1/4 inch jack it may possible have the positive and negative lugs intermitenly making contact and this will make a direct short.I had this happen one time to me on a Boogie 400+ head and that is what it was.

 

[Passinwind]

The tech was right that he's handcuffed unless you (or he) can see the problem again. "No trouble found" tickets are a drag to write, I did my share over the years.

You need to look at what you've changed between each episode. Location, location, location. There's a clue. This is a wild guess, but I think maybe when the amp was repaired mung of some sort was left in the amp, found its way into the switching jack, was eventually dislodged, and may well never haunt you again. Shipping materials can easily create that sort of problem when they migrate to the wrong place, so the amp may have left the repair facility in perfect order too.

You need to pay for supporting membership to get an avatar, and you can fill in your profile after going to the control panel box that's at the bottom of some pages on Talkbass, acccessed from the "Forum Jump". Best of luck, and welcome!

-----Charlie Escher

 

[ajb]

Thanks for all of the input everyone. I had not thought of the contamination and speaker cable angles. I ordered Speakon connectors recently so that should clear up any speaker cable issues, I think. As for contamination, would it be ok for me to go in there and do some dusting? I've never done anything like that, and don't want to damage anything.