Subway 44 Static Riddle

[soundchaser59]

I've had this Subway Rocket 44 a few months, and it has been flawless until tonight.

(at home in the basement, amp hasn't been moved in several days)

Suddenly it starts making this static noise, sounds like arcing, like a tube mightbe going out. But these are all new tubes, JJ and EHX. I unplugged everything from all of the jacks and the noise continues.

Turn all the knobs and the noise is still there. In fact, one knob - the rhythm gain knob - makes the static noise louder when turned up, but the noise remains when the knobs are turned off. None of the knobs makes the noise softer or makes it quit, and the rhythm gain knob is the only knob that can make the noise louder. Not even turning the masters up made the noise louder.

So I start tapping, and everywhere I tap I can hear the rhythm of my tapping in the static. The static noise is constant, and if I tap on the knobs, the static also matches my tapping. If I pound my fist on top of the amp the static stops for a minute or so, but it always returns.

The static reacts most of all when I touch my guitar cord to the rim of the input jack.

Some kind of rogue grounding issue? Loose wire? Loose solder joint? Something touching the chassis that shouldn't be touching??

 

[user 21540]

Hey man don't punch your amp - these guys are great little workhorses. It could be a grounding problem but I think you probably have a bad preamp tube. Even if they're new you can get duds that make noises just like you're describing. I own the Rocket 44 and I've had new production preamp tubes fail right of the box - JJs, EHXs and Groove Tubes. I've also had ones that go South very quickly (like a couple of months) and make static crackly noises that are then amplified by later gain stages in the preamp. The fact that the gain knob is in creating more noise when you turn it up may be related to this. It is more than likely the tube in the V1 position; but you might need to get a known good 12ax7 tube and try placing it in all positions one at a time. If you eliminate the noise in any position you've found the culprit. Mesa includes details of this troubleshooting technique in their downloadable .pdf manuals. You can do it while the amp is running pretty safely. If this doesn't work you might have another problem that a tech would have to look at.

 

[soundchaser59]

Yeah, you are probably right. I was hoping "new tubes" meant "good to go for a year or more with no issues." Wishful thinking at best, ayyyyy?

I have another EL84 Mesa amp here, I'll do some tube switching later tonight.

Don't worry, I wasn't pounding on it very hard, just enough to hear the static noise change. Won't even leave a bruise......on the amp! My hand is another matter. :mrgreen:

Love the sounds I get otherwise, it's slightly more gutsy and raw than the DC3 I have sitting next to it. 8)

 

[soundchaser59]

You can do it while the amp is running pretty safely.

NOTE: BEFORE CHANGING TUBES TURN POWER SWITCH TO OFF


page 13 in the manual

 

[user 21540]

http://www.youtube.com/watch?feature=player_embedded&v=wSl-l9aWDHw
You can pull out and replace one preamp tube at a time while the amp is in standby. This vid shows you how. The preamp troubleshooting stuff starts at 9.16. Hope you find the problem.

 

[soundchaser59]

BUMMER!

All new tubes, new preamp tubes, new power tubes. Played for 3 hours tonight without a glitch. Then the last two songs I turned both channels up just a hair and the static suddenly returned. Almost constant, I couldn't play anything without the loud arcing noise. Even if I turn the guitar volume way down and play soft, still had the arcing static noise. Which I hope means it isn't the speaker, which is a minty Weber Legacy 100 watt that I bought mildly used.

This sucks big time. I can't afford to have a tech go over this thing, but what else can I do......

 

[user 21540]

You could try cleaning all the tube sockets with contact cleaner. Spray some cleaner on the pins and carefully plug them in and pull them out a few times. I got the tip from here:
http://www.premierguitar.com/articles/8677
I also saw this on the JJ/Eurotubes website on this vid at about 1.28.
http://www.eurotubes.com/eurotubes-Generic-How-To-Bias-Video-Marshall.htm
If this fixes it at least you know your older set of tubes might still be good.

 

[soundchaser59]

You could try cleaning all the tube sockets with contact cleaner. Spray some cleaner on the pins and carefully plug them in and pull them out a few times. I got the tip from here:
http://www.premierguitar.com/articles/8677
I also saw this on the JJ/Eurotubes website on this vid at about 1.28.
http://www.eurotubes.com/eurotubes-Generic-How-To-Bias-Video-Marshall.htm
If this fixes it at least you know your older set of tubes might still be good.

Yup, I called Mesa today and the tech said I could easily spend $300 bucks by the time I let them go thru it and send it back......and they might not find anything more than bad tubes or dirty sockets. Main problem is getting the amp to have the problem while it's on their bench! If they can't recreate the problem, they probably can't fix anything.

I still think I should try my hand at doing some type of bias mod on this thing, so it will run just a shave cooler. I'm gonna yank the chassis out tonight and see what I see.....

Sucks especially because I need to be able to trust this thing for gigging. I have a back up, modded DC3 that's been gone over well recently, but I don't love the idea of lugging around two Mesa combos to every gig. I should save up for a Mini Rec and use that for a backup. Man I hate the thought of playing a gig and suddenly having mic'd thunder static coming thru my amp in the middle of a set.

 

[soundchaser59]

I did get in there tonight and deoxit the tube sockets and clean the jacks, including the footswitch jack. Realized I still had the MEsa preamp tubes in, so I took the new Tung Sol's out of the other amp and put those in the SR44. I was told the JJ's are new, so I have those in there as well, but I have some new EL84's on the way also.

I believe my SR44 has already been modded. In the schematic, for the bias supply section, it shows a 120K resistor after the 15K and 33K. It appears that (if there ever was an actual 120K resistor there) the 120K has been removed and in its place is a 15K and a 100K soldered together in series. It's a very clean job, but I doubt that the factory would have done it this way, so I'm assuming it has been modded. I guess lowering the Rk at this point would very slightly lower the bias voltage? I still think it runs fairly hot, but I'm not inclined to mess with it right now unless the problem continues.

Sorry for the poor photography skills, but you can get the idea of the resistor mod here....... you can see the resistor magic in between the blue caps and the red wire. (I swear there is not a single 33k - orange, orange, orange - resistor on this entire board! I couldn't find one!)

 

[user 21540]

The giveaway is that the resistor types are not the same as those used on the rest of the board. Sure looks like a mod. I have heard that Boogie will sometimes drop in a different value resistor than that specified on the schematic to match the power tubes they are using when the amps are assembled - but yeah, I doubt they would do it like that. More than likely they would grab one component with the nearest to correct value for the particular tubes.

Good luck solving the problem - intermittent stuff is always a headache. My Rocket 44 had some faulty components in the power supply circuit when I first bought it S/H that was causing the amp to switch by itself between the OD and Contour modes - but it didn't do it all the time. It was in the shop for several months after before it was (eventually) successfully repaired.

 

[soundchaser59]

The giveaway is that the resistor types are not the same as those used on the rest of the board. Sure looks like a mod. I have heard that Boogie will sometimes drop in a different value resistor than that specified on the schematic to match the power tubes they are using when the amps are assembled - but yeah, I doubt they would do it like that. More than likely they would grab one component with the nearest to correct value for the particular tubes.

Good luck solving the problem - intermittent stuff is always a headache. My Rocket 44 had some faulty components in the power supply circuit when I first bought it S/H that was causing the amp to switch by itself between the OD and Contour modes - but it didn't do it all the time. It was in the shop for several months after before it was (eventually) successfully repaired.

Yeah, when I called Mesa I said, "I have an old Subway Rocket 44...blah blah...." and the guy's first comment was, "Those aren't that old. When we say old, we mean from the 70's! That amp isn't really old enough to have capacitor issues." He seemed to think that 15 years should still be well within the strong and usable life of this amp and all of its components.

What shop was your amp in? Did you send it to Mesa? Or was it a local tech?

Our premiere amp tech here in Lincoln (Chuck Mathes, Mathes Amplification) died unexpectedly last Thursday. I was actually planning to let him look mine over, and had sent him a message Sunday night. Then Monday morning the groups on FB were buzzing about news of Chuck's death. And the only authorized Mesa dealer and service guy in my state was in Omaha at Russo's, and they just closed their doors.

I'd rather not send mine to Mesa if I don't have to, but they really are the closest experts I have. Otherwise, Monsta-Tone on here is an auth'd Mesa tech, but that would mean shipping to Hawaii!

 

[soundchaser59]

A small step for man kind......

Took out the Mesa preamp tubes, took out the Fender "GT" (Sovtek) EL84's, doused all tube sockets with deoxit, cleaned all 1/4" jacks.

After all this I put 'er back together (new Tung Sol preamp tubes, and supposedly new JJ EL84's) and played 'er loudly (louder than Sunday night when I had the problem) for 2 hours without a single glitch! Just killer sound, pure and simple. Hope this is all it needed. This amp did come from the Bay Area, so maybe a bit of Pacifica humidity took a small toll over the last few years? 8)

I'd still be interested in hearing which tech / shop finally resolved your issue.

 

[user 21540]

Glad you got it going. Great news.

I'm in Western Australia. A local guy called Peter Nessfield at P&N Electronics did the work. I wasn't all that happy with time frame (3 and 1/2 months) and in the end I had to fix the minor secondary problem of the intermittent reverb myself. He did however fix the primary problem with the channel changing and nearly two years later the fault has not reappeared, so I guess it was worth the $650AU that he charged. I actually paid $1300AU S/H for the amp - the owner did not disclose the fault to me but in retrospect I'm certain he knew about it. Live and learn I guess.

I've also had to put a new volume pot on the overdrive channel which was easy. The old one was causing a monstrous thump in the speaker somewhere between 0 and 1. Fixed now though.

I love the amp. For a 1x12 combo it is so freaking loud and powerful - it easily keeps up with my bandmate's Marshall JVM410h 100w which he uses with a 4x12 cab. So cool to have so much power in such a small and portable package. In the Contour mode leads just soar. I got tubes from this guy on eBay. Full set with JJ 12AX7s and Valve Art EL84s:
http://www.ebay.com.au/itm/190667552739?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

 

[cradlefish]

Great to hear your problem is hopefully gone!

I recently got a Rocket 44 5 days ago and it's an awesome combo! Too bad Mesa had to discontinued the model but i understand they don't rest on their laurels. I was on a look out for a combo amp that is light, loud and possibly have two channels. I really didn't want anything made from China...not saying it's bad, but from experienced I came across a few lemons and knowing that owning a few Mesa over some time that I like the sound and reliability of these amps.

I happened to stumble on a mint Rocket 44. It has two channels, 40/45 watts and it's compact! Test drove it and got a good deal!

This amp just sounds great! Has the Mark IV like qualities, it's versatile and loud enough to keep up with a drummer! I love it! I will take it out for jams, auditions and gigs instead of my Marks!

Just changed the preamp tubes to NOS and it even sweeter sounding!

The Rocket 44 rocks!

 

[soundchaser59]

I'm playing mine with a funk band with horns, and I have never had it up over 3 before they tell me "That's loud enough!" :mrgreen: It's more than ready for the job of standing up to a drummer and a horn section! If I put an EV speaker in it and use an extension cab, I could probably play a lot of the local brewpub venues without even mic'ing it.

 

[cradlefish]

I'm playing mine with a funk band with horns, and I have never had it up over 3 before they tell me "That's loud enough!" :mrgreen: It's more than ready for the job of standing up to a drummer and a horn section! If I put an EV speaker in it and use an extension cab, I could probably play a lot of the local brewpub venues without even mic'ing it.

Nice! I'm playing with an alternative rock band. I usually use my Mark IV, but don't like to always take it to the practiced spot so i figure a compact, medium light combo would be a good option and plus the R44 doesn't sound boxy especially when you crank it. I plan to keep it original, but if you get your speaker changed...let me know what you think.

If you play live at some point? I hope you video record it and youtube it. I think it would sound great!

 

[soundchaser59]

I stumbled on a heckuva deal, two EV Force 12 speakers for $150 bucks, and they work great. Put one in the SR44 and cranked her up.......WOW! :mrgreen: 8) That's what I'm talkin' about!

 

[cradlefish]

I stumbled on a heckuva deal, two EV Force 12 speakers for $150 bucks, and they work great. Put one in the SR44 and cranked her up.......WOW! :mrgreen: 8) That's what I'm talkin' about!

oh yeah! Have you tried it with V30? How does the EV Force compared to the stock?

 

[soundchaser59]

I'm gonna stick my neck out and say that I think I've solved the static riddle. I believe the Fender GT tubes that came with the amp were not made to take Mesa style abuse, and I think they were redplating.

After cleaning sockets, etc., and putting in new JJ tubes, it was still a bit hot. I removed the previously modded bias resistor. Someone had taken out the stock 120K resistor and put in a series pair 100K + 15K in an attempt to cool down the bias a bit. I removed that (and had to deal with a pulled trace loop while I was at it) and I put in a new 100K resistor. Put the JJ's back in and ran the thing for a good hour with no issues. Sounds great.

There is no contest with the EV Force, it's as if this speaker was tailor made for these amps. The Fane GSV30 was superb as well, but with the high end on the over drive tones, the EV leaves the others in the dust. Where other speakers get fizzy or buzzy, the EV just keeps spitting out honest tone. It's very impressive, I had forgotten how much I like them. I'll be going to the gym regularly just so I can continue to carry these speakers around.

 

[cradlefish]

i had a chance to take the rocket 44 to an open mic gig. Boy! is this sucker loud! I barely had to three and it was plenty! It had no problem holding it's candle against a hard-hitting drummer. Unfortunately, one of my preamp tubes was squealing after the third song. I made it through but it was pretty annoying. As it turns out, it was the v2...I replaced it and no more noises.

Great little amp that can rock it out!