Roadster -- Lost of a channel... LIVE :-/

[b0nkersx]

Thanks Dom!

 

[kick6]

I was thinking about this earlier today... I run my Boss Acoustic Simulator AC-3 in front of the amp and use it only with the channel 2, and to acheive an even volume with clean and acoustic, I must run the level at 80% on the pedal. Could it be the reason? I was doing the same thing before when I was using my Jazz Chorus for my AC-3 for my cleans.

Not sure how much signal boost that ac-3 gives, but roadster's get boosted by all sorts of pedals with no problems. Rectifiers are boost wh0res. I boost my lady with a maxonOD808 in a 4 channels when or if needed. Giving a strong acoustic clean signal could push a weak pre tube past its limits so being a tube problem is a small possibility especially with them being shipped with mass produced JJs. Other than than, something internal prob tripped out.

Something interesting to note is that he uses that AC-3 ONLY on channel two. So yes, it could theoretically be a problem with the pedal. He needs to plug directly into the amp to rule this out.

 

[BostonRedSox]

Something interesting to note is that he uses that AC-3 ONLY on channel two. So yes, it could theoretically be a problem with the pedal. He needs to plug directly into the amp to rule this out.

+1

 

[nismofreakish]

Just to be sure... yes I use my AC-3 only with the channel 2, but the pedal is in front of the amp so when I use my other channel I switch it off and the signal still does pass 'cause I don't have any problem with the other 3 channels.

I received my 12AX7 from my dealer, I'll check this out this weekend. I think I'll start with the V2 since it's the clean channel 'cause I don't understand how the V1 could be blown and not having trouble with the other channels.

 

[kick6]

Just to be sure... yes I use my AC-3 only with the channel 2, but the pedal is in front of the amp so when I use my other channel I switch it off and the signal still does pass 'cause I don't have any problem with the other 3 channels.

Right. I don't know about that specific pedal, but if its true bypass it wouldn't affect anything while its off. Just to be safe, I'd remove it entirely from your signal chain.

 

[nismofreakish]

remove it... you mean the time to make some tests? 'Cause I really NEED this pedal for two songs of my band, I just can't get rid of it. I know the AC-3 is meant to go into the PA while ON, but unfortunately, it's not possible at every venue so I must be reliable through my amp at any time.

 

[kick6]

remove it... you mean the time to make some tests?

Yes. I'm not suggesting you immediately go throw it in the trash. You just need to take it out of play while diagnosing the problem you're having.



EDIT: If you can confirm that it is the pedal causing the problem (and after researching that pedal I think it might be) I think I have a weird, but workable solution.

 

[nismofreakish]

If the pedal kinda worn out the preamp tube, it will work out at first with the new preamp tube. I'll just find out later if it blows again...

I think, in order, I'll try my amp once again (haven't played it 'til the gig), see if it's still "broken", if so I'll remove the AC-3 from the chain, if there's no sound, I'll turn off the amp and try replacing the V2 tube. Again, if it doesn't work, I'll try the V1... (anybody could give me a link for the preamp tubes' fonction and location? It's not in the pdf manual, thx!).

If after that it still doesn't wanna work... I'm screwed... it's gonna be tech time
After 1 1/2 week of playing... it's a shame.

 

[BostonRedSox]

Go to the Road King PDF. Same preamp tube layout as the Roadster. Remember that each preamp tube has a side A and side B. Because of this, if your problem is strictly in channel 2, it could be either V1 or V2.

 

[espboogie123]

V1 A = First Gain Stage (Input Stage)
V1 B = Second Gain Stage
V2 A = 3rd Gain Stage Ch. 1 & 2
V2 B = 3rd Gain Stage Ch. 3 & 4
V3 A = 4th Gain Stage Ch. 3 & 4
V3 B = Tone Stack Driver Ch. 3 & 4
V4 A = Reverb Return Buffer
V4 B = Reverb Send Driver
V5 A = FX Loop Send Driver
V5 B = FX Loop Return Buffer
V6 A&B = Phase Inverter

From the actual tube assignments... v2 would theoretically mess with ch1 AND ch2 on side A. Either way, swap the tube, if not then your prob lies somewhere else like said before.

 

[BostonRedSox]

V1 A = First Gain Stage (Input Stage)
V1 B = Second Gain Stage
V2 A = 3rd Gain Stage Ch. 1 & 2
V2 B = 3rd Gain Stage Ch. 3 & 4
V3 A = 4th Gain Stage Ch. 3 & 4
V3 B = Tone Stack Driver Ch. 3 & 4
V4 A = Reverb Return Buffer
V4 B = Reverb Send Driver
V5 A = FX Loop Send Driver
V5 B = FX Loop Return Buffer
V6 A&B = Phase Inverter

From the actual tube assignments... v2 would theoretically mess with ch1 AND ch2 on side A. Either way, swap the tube, if not then your prob lies somewhere else like said before.

Call Mesa man. The easiest phone call you can make. Tell them what is happening. Explain to them that it is solely a problem on channel 2. They will tell you to swap V1, and if that doesn't work V2. If you still have no luck, then they'll tell you to bring it to a tech. Tien tried explaining this to me on the phone, how tube problems can occur in one channel only, even though a tube shares functions with other channels. Needless to say, it seemed a bit too complicated for me to grasp, and I couldn't visually get what he was stating. Either way, he was right though and my intermittent issue on channel 2 was tube related.

We can all tell you what we think, but the best place to start and save yourself a headache would be to call Mesa. They aren't open today, but if you call Mesa Hollywood they are pretty knowledgeable as well. Mesa is open Monday through Thursday.

 

[nismofreakish]

Well, I brought my amp to a friend yesterday so we could look at it together (It was the first time since my gig). I forgot the footswitch so we had to turn the knob behind the head for switching the channel but still... my channel 2 was working!!!! So I really don't what to think of this... All the tubes seem to work well, my friend took a pen and gently knock on the preamp tube, nothing special. However, I haven't noticed that the V1 was positionned physically higher than others, so we didn't knock it. Still, I had a spare preamp tube with me and was willing to try stuff, but ALL channels worked... The footswitch seems to work well too.

I'll take another look at it later on today, but don't really know what to do though.

 

[domct203]

Maybe a bad footswitch cable?

Dom

 

[BostonRedSox]

It could also be a weak tube in V1 or V2 and only show up intermittently. I would just keep a spare with you just in case it happens again. Tien was talking to me about how intermittent tube problems occur because of the heat that is generated in tubes, that sometimes things move during that heat and possibly cause sound failures or anomalies. I hope you figure it out nevertheless!

 

[espboogie123]

Your roadster probably doesn't like that acoustic simulator pedal. My roadster would probably smack me silly if I stuck an acoustic simulator in her. Place it in front of your ch3 or 4 and it might explode!! :shock:

 

[nismofreakish]

Well, after some hours spent with the amp, it all works fine... I really don't understand, I put my volume higher than the gig and for much longer and nothing wrong...

However, went I turn on the amp, and even after that, there's a tube sound/noise I already told you about. Yesterday, my friend heard this and found it very anormal, he says it's like the filament inside a tube would be crooked or so, 'cause when we tilted the amp, the noise stopped. Maybe a tube is indeed weak, and make this trouble intermittent... it sucks though... I hope it won't happen again, at least not live...

 

[BostonRedSox]

Just remember that while other things can go wrong, most of the time tubes are to blame for the problems you listed here. The Roadster is very complex, and each side of a tube represents specific functions. Couple that with the fact that each channel in the Roadster contains more gain than the previous channel (and can generate more heat), it becomes easier to see why trying to figure out where exactly a faulty tube is can be a daunting task at times. Luckily, preamp tubes are fairly in expensive and do not need to be purchased in matched sets. More so, you know that your problem is somewhere in either V1 or V2. At the most, your expenses for swapping the tubes, should you choose to do so, will be no more than $40 USD. On top of that, your new amp comes with a limited tube warranty of six months. Call Mesa and they will send you a few tubes in the mail for free.

Keep rocking and don't lose confidence in your new Roadster. It was most likely a tube issue. Mesa's QC is fantastic.

 

[nismofreakish]

Thanks! I received a preamp replacement tube this week, after have spoken with my seller. It's just that before changing the tube, I looked at the amp one more time and finally decided to not replace any tube considering my channel 2 was back on track. But still, I'll swap the V1 or V2 if anything goes wrong.

Thanks a lot you guys!

 

[kick6]

If the pedal kinda worn out the preamp tube, it will work out at first with the new preamp tube. I'll just find out later if it blows again...

I think, in order, I'll try my amp once again (haven't played it 'til the gig), see if it's still "broken", if so I'll remove the AC-3 from the chain, if there's no sound, I'll turn off the amp and try replacing the V2 tube. Again, if it doesn't work, I'll try the V1... (anybody could give me a link for the preamp tubes' fonction and location? It's not in the pdf manual, thx!).

If after that it still doesn't wanna work... I'm screwed... it's gonna be tech time
After 1 1/2 week of playing... it's a shame.

I think there's a way to get past this, and have that pedal work better. How do you currently have that pedal connected as there are two different outputs on it?

 

[nismofreakish]

Yes one for the amp when on bypass and one for the PA. It's just that it's unfortunately impossible to plug in the PA in each venue, so I must have a backup plan, which is using my amp for the acoustic sound...