Crest CA9 Lovers speak up.

[pickles]

Short derail/sidetrack:
how exactly do you match gain structures ? - procedures ? tools ?

If you run well within the comfort zone of your amp, does it make any difference ?

Hook up the amp to a dummy load (IIRC I paid $10 for mine), play a constant input signal and measure the voltage across the load.

If you plan to A/B amps, don't bother unless:

1) you plan to do it blind
2) you gain match
3) you don't really want to know whether or not they sound different and plan to carry on with your preconceptions

 

[mrpackerguy]

I had a CA-9 for several years when I ran a rack set up. I tried QSC, Yamaha, Crown and the CA-9 was just head and shoulders above the rest hands down end of game. Yea, the weight is an issue, but haveing my rack set up in a rolling rack made it easier.

 

[alexclaber]

Why do all the Lightweight Amps need secret decoding when it comes to "Gain Matching" and all the Heavy Weight Amps are set up similar to each other?

Lightweights are aimed at pro/touring gear whilst heavyweights are aimed at DJs/semi-pro - pro gear works to a hotter line level reference.

Alex

 

[Bob Lee (QSC)]

You really don't even need a dummy load to set up gain unless the amp has an extremely low output impedance. Just measure the output voltage with no load attached. Set the amps up so that a certain input voltage results in the same output voltage.

 

[Bob Lee (QSC)]

Agreed.

Here is a question.

Why do all the Lightweight Amps need secret decoding when it comes to "Gain Matching" and all the Heavy Weight Amps are set up similar to each other?

Your question is asking the reason for a non-existent premise.

Compare the Crest CA amp with a Crest Professional Series amp. In that comparison, the Professional Series amp is the real heavyweight. Yet it has a much lower gain, so a casual comparison--with no matching of gain--would lead, say, a DJ or someone unfamiliar with how a power amp works to conclude that the CA is louder, ballsier, more arse-ful, etc.

 

[OldogNewTrick]

I know, I'm the dummy load here...

just for me to understand:
I measure the output voltage of the power amp(s) with a multimeter set to AC voltage. Do I measure between "+" and "-" or between "+" and ground/earth ?

Does one leave the output voltage of the pre-amp constant (Master volume setting) and adjusts the input attenuators of the power amp(s) until the measured output voltage reads say 57,2VAC ?

Input source to pre = signal generator (sine ?Hz)

After preparing thus, screen the power amps off, have somebody else do the switching about and pound away on your bass, while trying to hear any difference...

right ?

 

[Bob Lee (QSC)]

Put a steady audio sine wave tone into the power amp. Maybe 1 volt or so.

Measure the output voltage. Pick a voltage to adjust it to and adjust the amp's gain control to get it.

Do the same with the other amp and adjust it to the same voltage. If necessary, go back and adjust the first amp so that you can get them both the same.

When equal Vin on both amps results in equal Vout on both amps, their gains are matched.

 

[Red Planet]

Like I said before Matching the Gain between the two Amps is'nt going to help the Yamaha be something it is'nt.

You would have me believe that I can not tell the difference between the two after having tried Levels on the Yamaha in every concievable combination. The Yamaha will not give up the goods when pushed no matter if the input Level is cranked or turned down and my Pre Output is turned dow or cranked and evey position in between. I have tried it. Gain Matching is not going to give me more positions on my Level Controls that arent allready there.

Also I looked at the Input Sensitivity and not a lot of difference between the two Amps (2db difference). There is some difference but not much. With that minumal difference I should have allready found the "sweet spot" by now.

 

[Bob Lee (QSC)]

Maybe, maybe not. It could be the amp, or it could be user error.

 

[alexclaber]

Like I said before Matching the Gain between the two Amps is'nt going to help the Yamaha be something it is'nt.

What perplexes me is that you're using these amps into a Goliath IV. That cab can only handle a fraction of the output power of the P5000s. How can you judge an amp when the cab can't take the power? That's like testing the performance of a Corvette engine by putting it in a Mini!

Alex

 

[Red Planet]

What perplexes me is that you're using these amps into a Goliath IV. That cab can only handle a fraction of the output power of the P5000s. How can you judge an amp when the cab can't take the power? That's like testing the performance of a Corvette engine by putting it in a Mini!

Alex

You evidently havent read all of my posts.

The Cab takes either of these Amps fine with no problems. The Yamaha Clips occasionally and is way looser when craked but let me say it again the Cab takes either amp full up Bridged Mono.

Go back to the threads where guys suggest, for picking an amp for their cab, if using a SS Amp get an Amp that is rated over what the Cab is rated for rather than an Amp that puts out exactly what the Cab is rated for or you will hit a headroom cieling.

The G IV takes the RMX 2450 face first head on Bridged Mono with the Level Controls on the Amp Dimed and the Preamp Cranked. Nothing Hard Clips, no Distortion, very Tight, and Amazing Low End Toruque.

I'm a firm believer in using an amp that is way over rated for your cabs unless your talking about a Tube Amp.

 

[Kindness]

The Cab takes either of these Amps fine with no problems. The Yamaha Clips occasionally and is way looser when craked but let me say it again the Cab takes either amp full up Bridged Mono.

Physics tells us differently. If you aren't able to get enough power out of the amps to hit the limits of the cab, your input signal (into the amp) is not getting full power out of the amp.

 

[Red Planet]

Physics tells us differently. If you aren't able to get enough power out of the amps to hit the limits of the cab, your input signal (into the amp) is not getting full power out of the amp.

I think we get lost in percieved comunication rather than the facts of the Real World Situation.

I just went down to my Studio and Played my Rig for a while and I can definately say I'm getting some juice out of this rig. Cab limitts or not this thing will kick you in the gut. It's like standing next to a 90 lb Jack Hammer. It's that loud. For what ever reason with the QSC in the Mix it is flat pumping. The QSC is able to glide across the Peaks and keep pumping it out. I do, even more often with the QSC have the Clip Lights coming on but it just keeps a ticking.

Now part of all this could be the Input Selections on the QSC. I have the Amp set for Bridge Mono, Parellel Inputs, 50 Hz filter on, and Clip Limitter on.

As you can see in the Pics I'm running a Balanced Cable from the Preamp to the Poweramp and a Speakon Cable wired to take 1+ 2+ from the Amp.

I have the Preamp Input Gain set where I do not Clip the Input, I have very aggressive Playing Technique. The Aural Enhancer is set where I get some extra thump from it. The Bass is set for a little Low End Boost. The Parametric is set for further Jump Out and Kick you Tone. The Trebile is cut just a smidge (I get plenty of High End Snap). I have the Bass Intesifier Circuit Engaged for that extra Cannon in the Low End. The Solo Boost is on, Increasing Output a good bit and the Master is set a little over Half Way. And last but not least the Amp Input Level is set all the way up. Oh and the Compressor is set to react to my Extremely Agressive Playing Style just to even out some of my Massive Strikes when I'm really Thumping on my Bass.

You can get your Graph Paper and your Calculator out and say that cant do XYZ cause my Calculator says so but.........................

Can you say Kaaaabbooooooommmm!!!

Here are some Pics for Show and Tell.

 

[Red Planet]

It is freakin unreal what this rig will do now with the RMX 2450 in the Mix.

My only Problem is after understanding how much arse the Led Sled has I'm not sure the Yamaha will be able to give me the same Massive Performence replacing the RMX in my PA with it.

I'm pressed for time right now but when I get a chance I'm going to try the Yamaha in my PA. I have it hooked up and working but havent let the Throttle out yet. With the RMX 2450 in my PA running it at 2 ohms per side Stereo pushing 6 15's, at outside gigs it sounds like Thunder. Just not sure the Yamaha will do it so I may sell the Yamaha and put the RMX back in my PA and stick a C9 in my Bass Rig.

 

[Red Planet]

I must conceed after thinking about it, I might get similar results with the RMX if I turned off the Clip Limitter and the Low Frequency Rool Off switches in it. The Yamaha dosnt have that. It does have this odd little Bass Bost switch that is supposed to match it up better with thier Cabs (see below).



YS Processing
YS Processing (Yamaha Speaker Processing) achieves optimum matching with our popular Club Series loudspeaker systems. This special circuit optimizes output from the power amplifier to match the characteristics of Club Series speaker systems, resulting in extra-smooth highs and enhanced lows.

That in the Low End could very well be a Power Robber used as a Bass Amp with this thing engaged. Possibly overdriving the Amp when Pushed.

Anyway fixin to go crank my PA to see what the Yamaha will do in it, though Icouldnt really Test it out in my Studio like I could at a Live Gig.

 

[BruceWane]

I must conceed after thinking about it, I might get similar results with the RMX if I turned off the Clip Limitter and the Low Frequency Rool Off switches in it. The Yamaha dosnt have that.

Low frequency limiting does a whole lot for increasing headroom. Clip limiting doesn't technically increase headroom, but it does increase average power output without distortion - the real world result is more useable volume.

Is your Yamaha an older model? I don't see any limiting, but the user manual shows a sweepable low/hi cut filter............page 7........

[Invalid or Expired Link Removed]

It does have this odd little Bass Bost switch that is supposed to match it up better with thier Cabs (see below).

That in the Low End could very well be a Power Robber used as a Bass Amp with this thing engaged. Possibly overdriving the Amp when Pushed.

Certainly could be an issue. Boosting bass frequencies eats up headroom in a hurry. Dial in +10db@40hz via EQ and you'll see any power amp cry uncle in short order.

 

[Geddyfleaharris]

Oh and the Compressor is set to react to my Extremely Agressive Playing Style just to even out some of my Massive Strikes when I'm really Thumping on my Bass.

You can get your Graph Paper and your Calculator out and say that cant do XYZ cause my Calculator says so but.........................

Love the incredibly colorful and descriptive language of your post(s). Rock on!

Side note - are you replacing the QSC with a CA9? Or?

P.S. love the looks of those MM Preamps.

 

[Red Planet]

Love the incredibly colorful and descriptive language of your post(s). Rock on!

Side note - are you replacing the QSC with a CA9? Or?

P.S. love the looks of those MM Preamps.

Thank you, I do have that Neon Green thang going. Yes what I was talking about getting was a CA9 to go in the Bass Rig, put my RMX245 back into my PA and sell the Yamaha though I believe I have just dicovered what the problem was.

Fixin to post on it in a second.

 

[alexclaber]

I must conceed after thinking about it, I might get similar results with the RMX if I turned off the Clip Limitter and the Low Frequency Rool Off switches in it. The Yamaha dosnt have that.

Aarghh!!!!!!!!!!



That neatly goes back to my point about your cab not being able to cleanly handle full power in the lows from either amp - but if you use a highpass filter then you'll significantly increase the amount of bottom the cab can produce by removing wasted excursion below the tuning frequency. And a good clip limiter can get you another 3dB of output with almost no detriment to the sound.

Alex

 

[Red Planet]

Bruce you hit the nail on the head and Bob had asked about it before.

I'm a Knlucklehead!

I just figured out what is going on with the Yamaha.

I was overdriving the heck out of it.

I had gone over everything when I first got it and thought I had it set up correctly but I did not.

BTW someone asked how old it is. It is Brand Spanking New. I've had it just over a month or so.

I had the Bass Rolloff off and that little YS Switch was on. I'm sure this was causing this Amp to work double overtime.

Evidently I didnt quite understand that Bass Rolloff Circuit. It works in conjunction with the built in Crossover with a choice of using the Rotary Frequency Knob as a Crossover, Off or as an Adjustable Bass Rolloff. I had it turned off which was letting anything go through.

All that being said the QSC Clips nicer than the Yamaha. I turned off the Bass Rolloff and Clip Limitter on the QSC and low and behold Mega Massive. At that point the amp wasnt really struggling like the Yamaha but I dang near blew up my Cab (not really but one could). Even when the QSC is hard clipping it's not ugly like the Yamaha.

All this being said any issues eveidently did not have anything to do with Gain Matching, more me being a complete dummy.

How I found this on the Yamaha is when I went to crank it with my PA I decided to take a Peak at the rear of the Amp and then I realised that YS Switch was on and what the Low Rolloff Circuit will do. So I then set the Yamaha at about 40hz and turned off that YS Switch and cranked some Steely Dan. The Clip Indicators would occasionally light up but no harsh Slap Sound and it was Pumping. For a second I thought I had busted a 15 but then realized the Walls were vibrating.

When I get time (maybe tonight) I'm gonna pull it back out of my PA and hook it back to my Bass Preamp and try it that way. The reason for this is the Yamaha is 20 pounds lighter and would be much easier to carry and my PA Rack is huge anyway, Yamaha or not.

So I may can make this Lightweight Amp work afterall.

Any suggestions as to what Frequency to set the Bass Rolloff Crossover Knob? I want as much bottom end as I can get but not Overdrive the amp and not Over Excurse my Speakers.

Also as a side note with the QSC RMX Amp in the Bass Rig Pumping really hard the QSC Amp gets freakin hot. I mean it could double as a heater. The Yamaha does not put out very much heat at all. Is this a characteristic of the Swithmode Amps?

Also Alex I'm telling you this cab can handle a lot of SS Power. I guess you would have to hear it. I do agree it can not handle 2500 watts of super lows. I'm pretty darn sure the Yamaha does not have a Clip Limitter. More than anything in all this I have overdriven the Yamaha not the Cab but like I just said the QSC with the Highpass off will just about kill it. So I guess it would seem the QSC is capable of pushing through more in the super low department.