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EddieVanSilva

Power Amp Issue and Clipping

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With all the new threads about firmware updates and new cab models, I hate to go back to basics to talk about some issues I'm having, but here it goes...

 

Having only recently receiving my HD Pro, I'm still in the process of tinkering with it and trying to come up with decent tones. As of now, I'm running in stereo to a Rocktron Velocity 300, then into a 412 cab.

 

As I'm adjusting things, I'll be doing so at rehearsal volume, so it's pretty loud. Every now and again, I'll come up with a tone that to me, sounds decent, but on the highest 2 strings, when I hit a note, I hear, what sounds to me like, a short burst of clipping noise. The tones have distortion, but not extremely heavy (think older AC/DC). I have reverb and delays set up in moderation, nothing with heavy saturation. I'm not using any compression yet. You only hear it the very moment you hit the note, then it disappears when the note starts to decay.

 

On my old Vetta and other equipment I've used, like old proccessors, mixers, etc. I'm familiar with clipping. But all of those have an input level, and I don't see any place as of now to be able to adjust that. Now, while browsing the site, I came across a thread where someone mentioned to press in the pad button, as it's for guitars with hot pickups, so that's already pressed in, so it's not the problem.

 

The other issue is my Rocktron. I have zero experience using power amps for a guitar rig. I personally think that this amp shapes the tone very well. Tone-wise, I couldn't be happier. But today was the first time playing at rehearsal volume for any length of time. Normally I crank it up, then spend 20 minutes turning dials, play for 2 minutes, turn dials, etc. Today I only did minor tweaks, and got to devote some real quality time blasting some rock through my new rig. after about 20 minutes of solid playing, the amp was so hot I couldn't keep my hand on it for very long. I could "smell" it. Not an electrical meltdown smell, but in my line of work there are tools that get hot, and the paint used on the tool, housing, or whatever, starts to create a smell when it heats up. check connections, let it cool down to where I could comfortable rest my hand on it, and rocked out some more. Same thing. I have my HD Pro in the same rack case. It's a 6 space case, and as of right now from bottom to top it's: empty, rocktron, empty, HD Pro, empty. So there's empty spaces on both sides. After playing, the underside of the HD Pro was so hot I could barely keep my hand on it.

 

The fans on the Rocktron are on the side of it, and has vent holes in the top of it. So while it's in the rack case, the fans aren't directly facing the outside of the case, but front and back lids are off. I would have to think that, although amps can get warm, these things are designed to be in a rack case, right? I would assume that they designed it to be able to run with the fan NOT facing the open ends. But I do NOT want my HD Pro to melt down into a ball of liquid circuit boards while I'm playing a solo at a show. So any input guys? Sorry for the lengthy post. Thanks.

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I have no experience with the Rocktron, but I've been a rack guy for many moons...it's always a good idea to have a big enough rack so you can leave an empty space between the power amp and whatever unit sits above it. If it's a single space unit, you might even try leaving an empty space above and below it, if it gets that hot.

 

Back when I used to lug around a Marshall 9100 power amp (great amp, but 3 rack spaces and at least 60 lbs...never again, lol) I got a small fan that clipped to the back off the rack, to keep some air flowing across it.

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Yeah that's what I posted above, that starting from the bottom of the case, there's an empty space, then the amp, then empty space, then HD pro.

 

Like i said, I wouldn't be surprised if it got WARM, but even with an empty space between it and the Pod, the bottom of the pod was so hot I could barely keep my hand on it. Just don't know if something's wrong or not. the fan kicks on and off like it should. If that's just the way it is, I'll be pretty bummed, as the amp is neat, and even when I add my wireless to the rack, it will still be a lightweight rig. I didn't want to have to get separate cases, or go to a cooler running amp if at all possible.

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My Pod HD Pro doesn't get that hot, and I haven't heard similar reports in the past. You may have an electrical issue in your setup.

 

Are you using the external psu that came with your Pod HD Pro to power it?

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Well I don't believe the Pod itself is getting hot on it's own. I believe the Rocktron is putting out so much in that, even with a space between the two in my rack, it's causing the bottom of the pod to get hot.

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Yeah that's what I posted above, that starting from the bottom of the case, there's an empty space, then the amp, then empty space, then HD pro.

 

Like i said, I wouldn't be surprised if it got WARM, but even with an empty space between it and the Pod, the bottom of the pod was so hot I could barely keep my hand on it. Just don't know if something's wrong or not. the fan kicks on and off like it should. If that's just the way it is, I'll be pretty bummed, as the amp is neat, and even when I add my wireless to the rack, it will still be a lightweight rig. I didn't want to have to get separate cases, or go to a cooler running amp if at all possible.

Oops...guess I'm not paying attention today, lol. It could be malfunctioning somehow, I suppose. Fan would still be worth a try...

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Maybe you could place the Rocktron in the empty bottom space of your rack, or the HD Pro in the empty top place, leaving two empty spaces between the Rocktron and the HD Pro?

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Wow, i had a Rocktron V 100 and 300 and they never got this hot, even in a fully packed rack. I'm currently running a tube power amp and don't have any heat issues. I would consider moving on from that power amp if it was me - just sounds like something is not right. I moved on from the V300 just because I was hell bent on going tube, but the one I had seemed to work pretty well without heat problems - then again I didn't have it all that long.

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I had a Rocktron die at a large outdoor show a few years ago and wont use those power amps anymore.Lately I have been getting killer results with one or two EHX 44 Magnum power amps and a 1x12 cab and my HD500. Plenty loud and I think they will drive a 4x12. You can find them used once in a while.I have a bunch of amps and I have been using these little guys a lot for my gigs lately.The last gig was at a large casino/ big stage at pretty high volume. Sounds to me like that Rocktron is loaded with dust/dirt and may need cleaning/servicing or has bad solder joints somewhere.

 

Good Luck!

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thanks for the info!

 

Of course, I couldn't just stop there until I found out what was wrong. Yesterday I put the juice to it again, at a slightly higher volumer than before. I played non stop for awhile and it got warm, but nowhere near what it was like the other day. The only thing I noticed, is that I am running everything into a mesa cab, in stereo. I keep the speakers disconnected, so I can wheel the cabinet out of the way when we have band practice. But when I hooked it back up, I accidentaly plugged one cable into the 8 ohm side and one into the 4 ohm side. For running stereo, there are two 4 ohm inputs to run it in stereo, but I must have just reach back without looking. Would this make the amp run hotter?

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thanks for the info!

 

Of course, I couldn't just stop there until I found out what was wrong. Yesterday I put the juice to it again, at a slightly higher volumer than before. I played non stop for awhile and it got warm, but nowhere near what it was like the other day. The only thing I noticed, is that I am running everything into a mesa cab, in stereo. I keep the speakers disconnected, so I can wheel the cabinet out of the way when we have band practice. But when I hooked it back up, I accidentaly plugged one cable into the 8 ohm side and one into the 4 ohm side. For running stereo, there are two 4 ohm inputs to run it in stereo, but I must have just reach back without looking. Would this make the amp run hotter?

 

Generally you run an amp into a higher impedance cab without damaging anything (4 ohm output into an 8 ohm cab, as long as you're not red-lining the amp), you'll just lose power...but providing a smaller load than the amp is expecting probably isn't good...I would have thought that you'd blow a speaker before roasting the amp, but who knows? Always best to match impedance, then there's no worries.

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I played quite a bit more, with each output of the amp going into each of the 4 ohm inputs of the cab, and still have not noticed the amp getting extremely hot.

 

As for the Clipping sound, I played with it a bunch, but I just can't figure out what's causing it. I wish the Pod had a clip meter like a lot of other devices have.

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Try the amp/line switch it will change the strength of the signal hitting your power amp. You might be clipping the input of your power amp.

 

-Max

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HA! I know this isn't exactly on topic but I have a Rocktron 300 and I just came across this from Fryette...  O. M. G...  I am suddenly drooling...  lol...

 

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