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Power Amp Recommendations
- Thread starter Stranger Danger
- Start date
Square waves are Not nasty sounding. Grab a tone generator, or even a synth and listen to a square wave.
We all don't play sine waves anyhow. Soft clipping is an easy thing to add to a amplifier. Pedals can easily add soft clipping. Diodes add soft clipping.
SS amps dominate the world amplifier markets. They are constantly overdriven into clipping and nobody even notices.
Things have changed a lot since the sixties.
Power amps from the majors all are sonically the same. The specs and measurements are better than humans can hear. Look for features, price, warranty. A five year transferable warranty says a lot about the quality of an amp. The quality doesn't mean it will sound better, but it would be less likely to have a failure, and if it did the manufacturer would be there to back you up.
DSP is an over looked feature. Usually add $50 to the price. But it can do so much more like match a pre-amp to the amp. EQ, Delay, adjustable limiters.
If amps didn't have limiters they would suck badly. An adjustable one with a DSP is a good option to tone it up or down depending on what you want.
DSP is an over looked feature. Usually add $50 to the price. But it can do so much more like match a pre-amp to the amp. EQ, Delay, adjustable limiters.
If amps didn't have limiters they would suck badly. An adjustable one with a DSP is a good option to tone it up or down depending on what you want.
All right I've decided to go with QSC PLX as they seem to offer what I'm looking for. Thanks for all the suggestions.
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Actually you dont. That power rating is at a higher (10%) THD than almost every other amp is rated at. They did so, to meet their marketing claim, and reflect the performance numbers they thought the amp should have. It is also a measurement taken at 1khz. So while you may be 1000% satisfied with your amps performance and tone, the specs you quote dont mean much. They do not reflect how your amp performs in the same arena as other amps are measured in, and they do not tell you how quickly the small OT's start high passing your low end.
To the OP. I would take a serious look at the Crest ProLite series of amps. They are affordable, light, powerful, and have an input sensitivity that lets them play nice with almost any preamp.
s0c9
Supporting Member
Actually... if the 600w is the typical vendor RMS/Program rating.. with SS amps the rule of thumb is to power with 1.5 to 2.25x the RMS rating of the speaker, to handle headroom (transient peaks) and maximize speaker output levels.
IOW - that would make the need for an amp to produce 750w - 1350w per channel, or if single cab somewhere in that range in bridged mode. Most SS amps will not run less than 4-Ohms bridged.
PS: I own QSC PLX, PLX2, GX.. Crown XLS, Xti and Yamaha P series amps.
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s0c9
Supporting Member
Based on what source???
Here's sample of mine... been repeated many times over the years.. and I can find plenty more.
"The rule of thumb for the past 40 or so years that I am aware of is 1.5 - 2x the speakers long term power rating, sometimes referred to by old school guys as RMS power handling, incorrectly by todays standards."
Can my amp power a sub?
And it is based on a false understanding of an old JBL paper. The myth has continued for years. There is no such thing as underpowering a speaker. The only way you damage a speaker is over powering it.
s0c9
Supporting Member
I wasn't addressing underpowering.. I was talking about appropriately powering a speaker at a given rating to maximize output.
Underpowering is a whole different issue.
Yeah, 600 is a whole 1.1dB more.
EDIT: I did my sums wrong here.
What are you basing this assertion on?
There is actually a certain amount of truth to this and it has to do with the amount of negative feedback applied. Typical SS amps use a lot more of it than typical tube power amps. The more feedback you use, the more the series of harmonics under clipping is extended.
You understand it correctly.
No it isn't. Any pro level power amp will be extremely clean right up to its rated power (i.e. until the output waveform's peak amplitude reaches the DC rail voltage of the output stage). Hook a dummy load up to one and scope it. The clipping knee is abrupt in a typical SS amp whereas it's (typically) more gradual with a tube amp. The reason why is related to the amount of negative feedback used (which is related to the gain of the devices involved). As I said above, typical solid state amps use a lot of feedback which makes them a lot more linear in their, uh, linear range. Tube amps usually use quite a bit less which results in less pre-clipping linearity (via the inherent non-linearity of the devices) but typically better post clipping behaviour.
No class AB amp will run sine wave at its rated power for very long without generating a lot of heat and exhibiting losses related to that. Tube amps aren't somehow immune to this. Audio amps are not designed to (and don't need to be) to provide continuous maximum output power. Music is dynamic. Crossover distortion is potentially a problem in any push-pull amplifier, it is in no way limited to SS amps.
Exactly.
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To maximize output? WTH does that even mean? Underpowering isnt an issue. It doesnt exist.
In the sound reinforcement world, the 1.5-2x amp power: speaker power handling ratio is often used, because owing to the dynamic nature of music, average power to a speaker is much less than peak and speakers can indeed handle transient peaks well in excess of their rated power handling. Using a power amp rated for more power than the speaker it's driving allows a bit more transient headroom before amplifier clipping. This is perfectly reasonable and commonly done. It does mean you need to be judicious with how you operate things, though, because if you're running heavily compressed program material or the system limiters are clamping down hard, you clearly do run the risk of overpowering the drivers to the point of damage.
- Transistors operating on low-voltage supplies tend to have higher spectral distortion components than tubes.
- If we go to high-voltage transistors, operating on supplies comparable to those of the tubes, the distortion products are less objectionable. Unfortunately, the noise floor of such devices is much higher. The IRF822 was very triode-like in distortion yet suffered from a noise floor some 30 dB higher than that of the triode.
- No other active device possesses both the low distortion products and the low noise floor of the medium-mu triode--albeit at the expense of voltage gain.
- The distortion products of transformers are much lower than those of active devices, yet quite different in character. Note that the odd-order harmonic products tend to be higher in level than the even-order products--exactly the reverse of the tubes and transistors.
Try again, 465w -> 600w is +1.14 db, barely noticeable.
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