Which power amp for bass?

[babebambi]

If you'd like an underpowered single channel back breaker that won't fit in most rack cases let me know and I'll give you a deal!

and what would that be ?

 

[Sickneedhelp]

One could say that as long as one also said that the amp would not be putting out anywhere near 3600W like 99% of the time, only hitting that wattage level on very short occasional spikes.

The description does need to conform to average or typical real world use. No where near rated power 99% is a bit pestimistic. I'd also substitute the word "peaks" for "spikes". Spikes would apply if the manufacturer really skimped on power supply capacitors. The major players in the amp market don't (for good reason).

 

[bongomania]

If you go back and read Bob Lee's posts, he states quite clearly that 1/8 power is typical "real world use". 1/8 of 3600W is nowhere near 3600W. And it's just a word, but I'd call a sharp jump from 450W to 3600W a "spike".

For those who are still putting it together, the idea is that the amp's power supply and the wall outlet can (usually) both withstand or produce momentary peaks that are above what you'd expect just from applying Ohm's law to the printed specs. That's why some of these super-high-wattage amps seem to be breaking the rules--it has nothing to do with some magic property of Class D or so-called digital amps, and everything to do with the whole power system allowing some very brief excursions over the allowed ratings.

When you look at the amounts of power actually being used the vast majority of the time, all of the factors add up to well within their maximum ratings and conform to what you'd expect from Ohm's law.

Both sides are correct from their perspective.

No, that only applies to subjective issues such as "tone". It does not apply to physics, at least not at the level we are discussing.

 

[agedhorse]

The amplifier's power supply averages the short peak power demands, and the circuit breakers (for the most part) apply to average currents.

 

[Sickneedhelp]

If you go back and read Bob Lee's posts, he states quite clearly........

.....the wall outlet can (usually) both withstand or produce momentary peaks

Yes, Bob excels at communication. That was part of what made working with him in another life a real pleasure.

Keep in mind, if a typical wall outlet gets hit with a large peak, the voltage drops significantly. It can only withstand to some degree. It can't produce. As agedhorse said (also see post #45), the peak power comes from the supply caps that average out the demand.

Full circle - 3600 watt amp, normal use, 7.8 amps.

 

[johnk_10]

Full circle - 3600 watt amp, normal use, 7.8 amps.

the only problem with that statement is 'normal use', making the numbers associated with it, IMO, meaningless.

 

[Bob Lee (QSC)]

Yes, Bob excels at communication. That was part of what made working with him in another life a real pleasure.

Keep in mind, if a typical wall outlet gets hit with a large peak, the voltage drops significantly. It can only withstand to some degree. It can't produce. As agedhorse said (also see post #45), the peak power comes from the supply caps that average out the demand.

Full circle - 3600 watt amp, normal use, 7.8 amps.

Is that you, JD?

 

[Bob Lee (QSC)]

the only problem with that statement is 'normal use', making the numbers associated with it, IMO, meaningless.

It's explained earlier in the post and in some of the preceding ones.

 

[johnk_10]

It's explained earlier in the post and in some of the preceding ones.

yeah. i read that Bob.

 

[Sickneedhelp]

Is that you, JD?

..............................................................

 

[alexgeddy]

Kinda surprised the way the amps are specd never came up

..Most all power measurements or specs are into a resistive load.... not a reactive load like a speaker.... personal preference for me is the lead sleds like the crown MT1200, or Macrotech (expensive ) but worth it... Also the crest ca6 and 9 are great amps.... I was never and still am not a fan of lightweight switching power supply amps for bass.... If I had to pick one I would go with the stewart and put fans on the heatsinks as they have been know to shut off on a thermal..

my 2 cents worth !!

 

[dave_t]

If you don't mind some weight, consider picking up a used Mackie 1400 watt. Built like a tank. Because it has lots of protection, a high slew rate, and ability to constantly pump high current. All power amps are not the same. And IMHO, a power amp should not have ANY TONE... You could pick up a used one for about $400 or less. Mine is now a backup, because I use an integrated EA iAmp 800. Much lighter, etc...

 

[Ray man]

I just ordered the ElectroVoice Q44 MKII power amp.
I can't find a review on this so it looks like I'll be the first.

 

[edwinhurwitz]

I started with a McIntosh 2105 (back in 1979) and then to a CM Labs 920, then to a Mackie (I forget the exact model number) to a QSC PLX2402 and now use a Crest CA9. Out of all of those, the best tone has come from the McIntosh and the CA9. The CM Labs was also a great sounding amp, but a little finicky due to age and abuse. I found that the Mackie and QSC didn't really give me the low end I like.

I got the Crest on ebay for $400 plus shipping, so good deals are out there. I've heard all the arguments about how, properly used, power amps sound essentially the same, but I'm not buying it. I know all about gain structure and the psycho acoustic phenomenon of how the louder signal will sound the best, but there is much more to amp design than input gain. Amps do differ in tone. Flame away!

 

[Bob Lee (QSC)]

Mackie, QSC, Crest, and McIntosh amps don't EQ the low end. Tone differs much more in human hearing than in power amps.

Input gain on most amps typically ranges from 0.5–2, with unity gain probably being most common. Most of the gain is in the output stage.

 

[Sickneedhelp]

..... there is much more to amp design than input gain. Amps do differ in tone.....

I agree completely. The CA9 does in fact have a low end advantage (eq without being eq). Bob knows why, but he may have to refresh some memory cells.

I've made a 40+ year career of demonstrating differences in amplifier sound. Some easily and repeatedly hear differences, some don't. This is obviously a controversial topic, yet certain amp models get continued praise from many. There must be a reason.

 

[bongomania]

I've made a 40+ year career of demonstrating differences in amplifier sound. Some easily and repeatedly hear differences, some don't. This is obviously a controversial topic, yet certain amp models get continued praise from many. There must be a reason.

I'm sorry, but this post is tantamount to saying "I am a huckster and shyster, preying on the ignorant and gullible".

I will only retract that statement if you can specify the methods you have used for eliminating bias in the listeners, or oversampling to correct for spurious responses.

Additionally, saying "there must be a reason" is not logically acceptable--the "reason" could be totally different from what you assume. So either you know the reason, and can demonstrate it factually, or you are just hoping people just nod their head in agreement without questioning.

 

[Bob Lee (QSC)]

It's easy to give amps--even identical ones--tonal differences without EQ or circuit modifications, especially in the low end.

If they're good amps, it's also easy to make them sound the same.

 

[Sickneedhelp]

I'm sorry, but this post is tantamount to saying "I am a huckster and shyster, preying on the ignorant and gullible".

I will only retract that statement if you can specify the methods you have used for eliminating bias in the listeners, or oversampling to correct for spurious responses.

Additionally, saying "there must be a reason" is not logically acceptable--the "reason" could be totally different from what you assume. So either you know the reason, and can demonstrate it factually, or you are just hoping people just nod their head in agreement without questioning.

I'll go with ""I am a huckster and shyster, preying on the ignorant and gullible". That best explains my career.

 

[mulchor]

Mackie, QSC, Crest, and McIntosh amps don't EQ the low end. Tone differs much more in human hearing than in power amps.

Could you clarify this for me please?

My one and only PA amp is a Mackie FR series (the M1400i)
Both channels have low end EQ in the form of a variable high pass filter. (it also has some high freq boost thing that I've never messed with)

My question is this. Do you consider the HP filter not EQing the low end, or is my amp an exception?

I agree with your second statement. The power amp just makes it louder with way less added character (good or bad) than any instrument amp.