maximum clean headroom from axe fx and atomic reactor fr

[joegold]

hey guys,
yeah i have a compressor in my signal chain, i'm using the output 1 (xlr out), i'm definitely not clipping the input of the axe fx, and i run the atomic fr all the way up. i'm very shocked too considering that the axe/atomic combo cranked is only as loud as my 40 watt tone king meteor set at about 4 or 4 1/2. it's puzzling and it stinks because i wanted this setup to work for all of the different types of gigs that i do.

If you haven't set up the compressor's controls well then it might be limiting your output.
Turn the Compressor Block's Level parameter up such that when you slam the strings the volume is the same with the comp on or with it bypassed.
This will have the effect of making your quiet passages noticeably louder but it will give you the same amount of potential level whether the comp is on or off.

 

[joegold]

I stated very firmly in another thread that i would never consider using any 2x6L6 amp with an Axe-Fx. This is why. Your experience could serve as a textbook demonstration of the basis for my statement.

Nice to finally agree with you on something Jay.

Unless Atomic is doing something that's never been done with a 2 X 6L6 power amp in order to get much more headroom than any other 2 X 6L6 power section has ever produced, it won't be clean enough at contemporary gigging volumes (these days drummers tend to hit their drums pretty hard) for either loud clean dark jazz block chording or bright clean R&B chording.

Hell.... Even 4 X 6L6 power sections usually start breaking up if you're playing loud and clean with a loud drummer.

Of course, if there's a PA and you're being mic'd and you have your signal in the monitors too then you don't need that much power.
But I always *hate* hearing myself in the monitors.
But I'm not playing FRFR yet with the Axe when playing live.

My impressions of the Atomic FR is that it's supposed to be used like a personal monitor while you send the same FRFR signal to the FOH. If you can't get it loud enough to hear it well then you should try getting it closer to your ears.
If there is no FOH system and you've got a loud gig to do then the Atomic FR is probably not suitable at all.

 

[jhuggins]

(I can't imagine what in god's name you all need 400-500 watts of clean headroom for)

It's technically not "headroom," it's allowance for a signal property called crest factor, which is the ratio of the maximum peak power in a signal to the average power. Power amplifiers are rated for their abillity to deliver a sine wave, which has a crest factor of 3dB. 3dB is a power ratio of 2:1, which means that a "100 watt" amplifier can deliver maximum peaks of 200 watts without clipping. The crest factor of an uncompressed guitar signal ranges from 15 - 27 dB, or power ratios from 32:1 to 500:1. That means if you want an average signal of, say, 5 watts, delivered to the speaker (which would produce ~105dBSPL at 1 meter from a typical speaker), you could need as much as 2500 watts peak power (i.e. rated amplifier power of 1250 watts) in order to deliver the signal with no possibility of the amplifier ever being driven into clipping. And you'd then have zero "headroom," because you're using all the available power in normal operation.

Now, most amp sims - even the clean ones - are going to introduce some compression, and the thing compression does is reduce the crest factor of a signal. From the above, it should be clear that this is a Good Thing. Practically speaking, if you want to play gig volumes with a horn band and you're not relying on PA gear for stage volume, you need 400-500 watts from an SS amp. If you must use a tube amp as a linear amplifier, the kinder, gentler overload characteristics of such amps will let you cheat the crest factor allowance a bit further. IME, a 4x6L6 tube amp with speakers of sufficiently high sensitivity can cut it, at the expense of size and weight.

but you should most certainly hear a volume increase between 200 and 500 watts....

The Atomic Reactor FR produces 50 watts, not 200. Given the tube/ss differences outlined above, my educated guess is that the practical difference between the Atomic and a ~500 watt FRFR system with similar speaker sensitivity would be on the order of 4-5dB clean output. Not overwhelming, but certainly significant.

Thank you so much for taking the time to clear that up for me, I learn so much from you. I know there's really no official way to do this and this may be a pretty stupid question and if so excuse my ignorance, but is there a way to compute how much headroom/crest factor a tube linear power amp would be compared to a solid state, looking back I realize I can't just take the power handling rating for solid state given by tom at 200 watts and assume this would be the same as the 50 watt tube amp that drives it in the active cab... In other how many solid state watts should I be using to have a similar volume and headroom result as 50 tube watts. You may have to read between the lines and overlook some of the phrasing as this is all new to me. Thanks in advance

 

[jb70]

hey joey,
i have my compressor block set up like you said and i have the mix set at about 30% so it's not that. i had the atomic on the floor tilted back with it aimed at my head. maybe i'll try putting it on a chair closer to my noggin this saturday. thanks for all of the replies guys.

jack

 

[joegold]

i had the atomic on the floor tilted back with it aimed at my head.

You might need 2 of the Atomic FRs then for gigs like this.

 

[joegold]

Oh yeah...

If it hasn't been said already, you should use XLR connections between the Atomic and the Axe.
The XLR outs of the Axe are actually 6dB louder than the 1/4" outs.

 

[jb70]

i'm definitely using the xlr output. i'm not getting 2 of these suckers! one 45 lb enclosure is more than enough for me (plus i have a 4 floor walkup when i get home from my gig at 3am- not fun!!!).

 

[Jay Mitchell]

If it hasn't been said already, you should use XLR connections between the Atomic and the Axe.
The XLR outs of the Axe are actually 6dB louder than the 1/4" outs.

Regardless of whether you use the balanced or unbalanced outputs, the Axe-Fx will easily drive any power amp beyond clipping. The balanced output will produce a maximum level +18dBu. That would make the unbalanced one good for +12 dBu, and you can drive any power amp to clip at +4dBu or less. There are lots of good reasons to use the balanced out whenever possible, but lack of headroom on the unbalanced one really isn't a problem.

 

[joegold]

If it hasn't been said already, you should use XLR connections between the Atomic and the Axe.
The XLR outs of the Axe are actually 6dB louder than the 1/4" outs.

Regardless of whether you use the balanced or unbalanced outputs, the Axe-Fx will easily drive any power amp beyond clipping. The balanced output will produce a maximum level +18dBu. That would make the unbalanced one good for +12 dBu, and you can drive any power amp to clip at +4dBu or less. There are lots of good reasons to use the balanced out whenever possible, but lack of headroom on the unbalanced one really isn't a problem.

All I know is that when I use the unbalanced connectors between the Axe and my SLA1 I don't get enough volume for the gigs that I play and when i use the XLR connections I do get enough volume.
And I have yet to clip the input of the SLA1 either way.

 

[jb70]

hey joey,
just curious- what is your current setup?

thanks,

jack

 

[joegold]

hey joey,
just curious- what is your current setup?

thanks,

jack

Axe Ultra into Art SLA1 into 1 or 2 open backed Pearce cabinets with EVM-12Ls.
Usually just 1 cab.
It's been plenty loud, clean or overdriven, for any of the gigs I've been doing with it.
I also use a Behringer FCB1010 foot controller with the UnO eprom.

 

[jb70]

ahh... nice rig! do you prefer the power amp/1x12 rig to the frfr route? i have been thinking about getting a stewart world 1.2 power amp and a port city 1x12 rig similar to yours. how heavy are those pearce cabs with the ev's?

 

[joegold]

ahh... nice rig! do you prefer the power amp/1x12 rig to the frfr route? i have been thinking about getting a stewart world 1.2 power amp and a port city 1x12 rig similar to yours. how heavy are those pearce cabs with the ev's?

The cabinet's weight is quite tolerable. I don't know the exact lbs.
My rack's weight is also tolerable.
It's quite a bit lighter overall than my previous rig consisting of a Triaxis a G-Major a System Mix Plus in a rack running into a Mesa Simul-Satellite powered cabinet.

My early experiments with FRFR systems and the Axe were OK but not "all there" for live playing.
I've played two theatre shows with the Axe going into a Traynor keyboard amp and although it wasn't "all there" it was pretty damn good for that type of thing.
The hi-end QSC and FBT powered monitors aren't readily available up here in Toronto.
The best FRFR stuff I've been able to try the Axe through has all been made by Yorkville.
Again, not "all there", for me.

 

[JMZ93]

This discussion reminds me of some comments I read once, on Frank Gambale's site. He almost always runs through PA gear because he says traditional guitar amps don't get nearly loud enough. then again, he's used and actively promoted those Yamaha DG modelling amps and that nasty Carvin "Tone Navigator" preamp in the past, so I don't take his comments about sound all that seriously.

I can't find the original comments - he says on his site he's using a Carvin DCM-1000 now, with the aforementioned preamp. bleck.

 

[Jay Mitchell]

This discussion reminds me of some comments I read once, on Frank Gambale's site. He almost always runs through PA gear because he says traditional guitar amps don't get nearly loud enough. then again, he's used and actively promoted those Yamaha DG modelling amps and that nasty Carvin "Tone Navigator" preamp in the past, so I don't take his comments about sound all that seriously.

You're missing the boat here. We're not talking just loud - hell, an 18 watt guitar amp can do that - we're talking clean - really clean, possibly with substantial low-frequency content - and loud. Even a 100-watt tube amp will not stay as clean as I would like when it has to keep up with the horns in a big band.

Some types of guitar sounds place much greater demands on amp headroom than others. If you ever have to play really clean with a horn band, you'll get the idea.....

 

[steveb]

It's technically not "headroom," it's allowance for a signal property called crest factor, which is the ratio of the maximum peak power in a signal to the average power. Power amplifiers are rated for their abillity to deliver a sine wave, which has a crest factor of 3dB. 3dB is a power ratio of 2:1, which means that a "100 watt" amplifier can deliver maximum peaks of 200 watts without clipping. The crest factor of an uncompressed guitar signal ranges from 15 - 27 dB, or power ratios from 32:1 to 500:1. That means if you want an average signal of, say, 5 watts, delivered to the speaker (which would produce ~105dBSPL at 1 meter from a typical speaker), you could need as much as 2500 watts peak power (i.e. rated amplifier power of 1250 watts) in order to deliver the signal with no possibility of the amplifier ever being driven into clipping. And you'd then have zero "headroom," because you're using all the available power in normal operation.

Jay, this really helped me alot in understanding this. My next question would be how do you pair this wattage up with speakers? If I'm running 500watts of solid state power, what wattage of speakers do I need to be running to keep from blowing them? How much allowance is there in for example a "70 watt" Celestion or a "200 watt" EV?

 

[gsegal]

Hey guy's just to chime in here. I know jbroad personaly and I can vouch for his ears and musicianship to say that the atomic is definately lacking in clean headroom. I used it on jazz gigs and it was fine and I was very happy with the results. I have yet to use it on an r&b gig so I was surprised when jbroad called me and told me about his gig and how much the amp was distorting. I live in an apartment in brooklyn so its kind of hard for me to crank the amp here but one afternoon when the neighbors were out I gave it a try at matching the output volume with the bypass button as tom suggested. I dont think you can get away without using a PA for a full funk band with keys and horns. The clean started distorting around 7 oclock on the output of the axe and although thats loud in a room I think it's gonna be a little low with 9 piece band. I think it would be fine for any other gig but you really have to spank the guitar for that style to sound right and being as clean as possible is a must. I may be wrong and I hope I am, because I really like the way the axe sounds with it and if anyone has a different experiance with it I would love to hear about it. This is just my opinion and I'm not puting down this product in any way. It has brought out the best of the axe for me for sure. Before the axe I had two amps for different gigs so this is something that I may look in to, but I certainly want to keep the atomic because it really does sound great!

 

[laxu]

This discussion reminds me of some comments I read once, on Frank Gambale's site. He almost always runs through PA gear because he says traditional guitar amps don't get nearly loud enough. then again, he's used and actively promoted those Yamaha DG modelling amps and that nasty Carvin "Tone Navigator" preamp in the past, so I don't take his comments about sound all that seriously.

Those Yamaha DG amps were actually really damn good sounding. I had one of the combos for years and liked it a lot. Still the best user interface in a modeler too.

 

[srooijens]

Those Yamaha DG amps were actually really damn good sounding. I had one of the combos for years and liked it a lot. Still the best user interface in a modeler too.

+1

I liked my DG-1000 a whole lot better than anything Line6 ever produced.
I quickly got rid of it after getting my Axe-Fx though.
I was also building myself a really cool tube preamp before getting the Axe-Fx.... I never finished it even though it was close to being done.

S.R.

 

[stevorc321]

It's interesting that a few people have said that a 2 x 6L6 power section won't cut it for this type of gig, but the OP has said he has had great results for years in the band with the 40 w Tone King (2 x 6L6 I presume??). Why would the amp smoke the reactor? Is the horn on the reactor breaking the sound up unpleasantly when pushed? Is the whole reactor less efficient than a 1 x 12 combo? I'm just speculating because I'm genuinely interested in trying the reactor - but I also have a funk gig, so I hope it can deliver on a loud clean. Perhaps the 200w passives are a better option for this type of music?