Powered PA mixers question

[daz]

I have this old peavey single amp 6 channel mixer i have used for gigs many times for years. It's an oldie but it has a huge power tranny and weighs a tone. At one point years ago i bought a much newer carvin with lots of features and not antiquated like the old peavey XR600c. Tried it at a couple gigs and while plently loud, no matter how we EQ'd the mics or how loud we had it we couldn't hear our vocals worth $hite and i returned it after we realize no way it would cut it. Then got a newer peavey with dual amps like the carvin and same issue. Ended up selling that one for a loss due to no return policy.

What i think the reason was is that the old peaveys huge power tranny could handle loud transients while the 2 new mixers we tried had those light weight toroidal trannys that maybe can't handle transients near as well? We're a fairly loud classic rock band. So am i right about this and if so OR even if not, what spec or other thing should I look for in a mixer to compete with the old peavey's punchy defined vocals? By the way, the peavey and mixers we tried all were in the same general range of wattage.

[pdf64]

When comparing ‘digital’ (class d & smps) to analog (class b & linear ps) power amps, may need to apply the same 2x ratio as was received wisdom when comparing solid state to valve amps.

I’ve not tried one of the newer pa amps, but have noticed a similar thing with lunchbox kilowatt bass amps, ie with the same speakers in band context, an 800W digital can just about keep up (protection light flashing) with a 250W solid state or 100W valve amp.

It may be due to the power ratings being based on the basis of high crest factor signals, whereas a sustained, continuous rating is more appropriate to our purposes.

[daz]

So would u then say to cop the same transient response and power of the old fully analog 210w pv i would need about 800w in one of the newer PAs that i assume are mostly class D?

[glebert]

It would help to know which models the newer heads were. I know some Carvin amps had some odd power ratings, and some of their amps just seem super quiet relative to their power rating. It can also be hard to compare different amps if they have a different gain profile. I have some bass amps that are 700+ watts that seem really quiet until you crank the level up to 8 or more, and then they get really loud really fast. But if you just think "I never had to run the old amp passed noon" then the new amp *seems* lower powered even if it really isn't.

[daz]

Couldn't tell ya, it was a long time ago. Not even sure i could tell you if it were only a year ago. But i can tell you they were plenty loud. Just that the vocals were hard to hear for the singers due to the transient response. Like having a guitar tone with zero attack.

[glebert]

Well, if they were class D they do have to roll off the very, very high frequencies to eliminate the rail-to-rail switching. Those frequencies are above the ability for humans to hear. That being said on a sharp transient when driving a electro-mechanical device like a speaker I wonder if there would be a detectable difference in the acceleration of the cone (or whatever creates the sound) with those additional high frequency components. After all if the energy is sent to the speaker is has to go somewhere, mostly into heat but maybe some into motion.

[daz]

Heres another question regarding a used mixer i am looking at. When they gove the power specs and say "both channels driven", does this mean if u only use one side it will be different? More clean power? Less? Or if thats not what it means, what ? Heres the specs... https://www.ccisolutions.com/StoreFr...AC-PPM808S.PDF

[glebert]

I would think that "both channels driven" is basically signifying the power supply can keep up delivering enough power for those levels with both channels. Maybe you could get a few more clean watts out of a channel if you only used one side, but I wouldn't think it would be at all significant.

[pdf64]

So would u then say to cop the same transient response and power of the old fully analog 210w pv i would need about 800w in one of the newer PAs that i assume are mostly class D?

I think that a digital amp's initial transient response should be ok, rather it would tend to be more of a sustained high power usage that would have it running out of steam.

[daz]

I think that a digital amp's initial transient response should be ok, rather it would tend to be more of a sustained high power usage that would have it running out of steam.

Why? Due to heat?

[nickb]

We really have to proceed with caution here as so much depends on the system architecture. It's too simplistic to just compare l tube / SS / class B / class D.

What were the model numbers of the Carvin and Peavey that you didn't like?

Here something to chew over. I've annotated this chart of class D efficiency with the actual power dissipation of the class D amp normalized to a 1 watt output. It doesn't change much as output increases. Therefore, heat should not be an issue even at continuous high power.

[daz]

see post 5 reply to post 4.

[pdf64]

Why? Due to heat?

My guess is that as they warm up, it may be that they apply aggressive processing to limit / attenuate the input signal, mitigate the risk of further heating. That could be made up nonsense though