I recently did a test running one of my class D PA amps against my hifi (cambridge audio azure power amp). This was done through my hifi speakers (focal aria 926). PA amp drove the left speaker whilst the cambridge drove the right. When sat at a distance with not great room acoustics it sounded like the same amplifier driving both speakers. But putting your head right next to the drivers and moving going back and forth between the left and right speaker there was a noticeable difference. The cambridge amp just had greater high end detail and better separation of the midrange elements. Id say the difference was comparable to testing a 500 quid integrated hifi amp versus my a mid / higher end power amp.
It got me thinking that maybe for my PA system I could move away from the high power class D amps for the top end (dual diaphram coaxial compression drivers - 700hz up) and perhaps go with a much lower powered class AB amp instead. I believe these are inherrently much cleaner at the top end than class D. I'd need a 2 channel amp per driver / stack and ideally with the ability to set rms / peak limiters via DSP.
There was one unit I found which does seem to fit the bill, the QSC XTi 1002. Has all the attributes and isnt too expensive per unit, but the question is would I be wasting my time even obtaining and trying this amp. Will it actually have a cleaner top end more on par with my hifi power amp? Or should I just get saving and go with a higher end class D amp instead ( powersoft, mc2, linear research etc). Any thoughts appreciated.
It got me thinking that maybe for my PA system I could move away from the high power class D amps for the top end (dual diaphram coaxial compression drivers - 700hz up) and perhaps go with a much lower powered class AB amp instead. I believe these are inherrently much cleaner at the top end than class D. I'd need a 2 channel amp per driver / stack and ideally with the ability to set rms / peak limiters via DSP.
There was one unit I found which does seem to fit the bill, the QSC XTi 1002. Has all the attributes and isnt too expensive per unit, but the question is would I be wasting my time even obtaining and trying this amp. Will it actually have a cleaner top end more on par with my hifi power amp? Or should I just get saving and go with a higher end class D amp instead ( powersoft, mc2, linear research etc). Any thoughts appreciated.
Yes it is, but the thoughts after comparing the two lead me to wonder how I can make the top end in my PA system better. That's the point of the post. It must be possible within a reasonable budget and I'm wondering how. Maybe class D can deliver this potential but I suspect it would be very expensive (e.g. a top end linear research amp). Typically PA amps use class D for power potential rather than fidelity. I dont need much power for the coaxials so can aim for fidelity but whatever unit needs limiters.
The PA amp didnt sound that much different and I dare say a lot of people wouldn't notice, It did really well considering its not even half the price of the cambridge audio pre and power combo, yet has twice the number of channels and can deliver 10k rms of power.
The PA amp didnt sound that much different and I dare say a lot of people wouldn't notice, It did really well considering its not even half the price of the cambridge audio pre and power combo, yet has twice the number of channels and can deliver 10k rms of power.
why not pa class ab(or gh whatever same) for tops and pa classd for subs? and buy better quality amp for tops?
using different class amps, how much of phase difference will there be, for sure all that logic in classd has more delay then class ab?
if you have something like dbx driverack or similar probably not issue.
im curious but could test this as i have serviced old phonic amp recently and was just thinking about similar thing, using behringer nx6000 for subs and phonic max860 for tops. so far tested on same speakers phonic has lot less bass or somewhat weak bass im not sure what exactly so clearly classd is better suited for sub duty. or may be class ab sounds brighter as there is less low end?
also using my tpa3255 for pa active speakers somewhat fullrange, very pleased with results, plenty of power and quality, TI does claim tpa is "hifi", so technicaly thats it.
using different class amps, how much of phase difference will there be, for sure all that logic in classd has more delay then class ab?
if you have something like dbx driverack or similar probably not issue.
im curious but could test this as i have serviced old phonic amp recently and was just thinking about similar thing, using behringer nx6000 for subs and phonic max860 for tops. so far tested on same speakers phonic has lot less bass or somewhat weak bass im not sure what exactly so clearly classd is better suited for sub duty. or may be class ab sounds brighter as there is less low end?
also using my tpa3255 for pa active speakers somewhat fullrange, very pleased with results, plenty of power and quality, TI does claim tpa is "hifi", so technicaly thats it.
Audible differneces between power amplifiers are more obvious with compression drivers IMO. Damo what amplifiers are you using in your system now? I have class AB amplifiers powering my larger passive PA system while the powered speakers in my inventory are all class D of course and in this case the class AB amps definitely sound better. I have also had the opportunity to compare several different power amplifiers back to back on occassion and there are some subtle differences that can be identified when doing that, this is the only way to know if what you hear is real of just in your head.
Currently running soundgear saturn 10 amps (3 of them). They are powerful and the PA does sound good. The improvement of my hifi amp was subtle and I wonder how that would actually translate at war levels over the PA. But finding something else to drive the tops, if better, adds the benefit of freeing up 4 channels for additional subs and kicks as well.
I've been on the same boat before, I had DIY 4 channel super leach driving my DIY 15" tapped horn for low and also DIY closed baffle for mid-top. I liked this for many years and man - it was really worth the trouble of having 100% DIY (thanks to DIYAudio). But, when I tried 25 watts PASS amps such as VFET push-pull, VFET SE and M2 driving mid-top, this brought another significant improvement. To my surprise, such a good sounding 25W amp (with sufficient voltage swing) can be heard from few blocks away.
i wouldn't say marginal gains...but i also lived through the Carver PM1.5 era...it got popular because of weight and size reduction per watt compared to anything else on the market at the time but over time they became known for a "veil to the audio quality" and as they aged the protection circuits became problematic, long story short when replacing them it was common to hear users say " now that i've got better AB class amps in my rig everything sounds better!"
The differences between decent quality class AB amps is usually fairly subtle, the step from class D to AB is more significant in my experience more like the difference between MP3 and wave when the source recording is analog. Of course your milage will vary so you won't know until you try but I think it would be worth the effort.
it's nice that these new amps have these filter features built in and limiting too, i still would want a dedicated x-over or system controller handling those functions then i'd look for a bare bones amp that sounds good.
i have fond memories of Qsc Mx 1400's running the mid & high of my Martin rig.
i have fond memories of Qsc Mx 1400's running the mid & high of my Martin rig.
I'm using a Xilica crossover which has all that, but I prefer to have limiters on all the amps as well, as a fail safe. Particularly for the compression drivers they aren't cheap (bms 4594s) and I don't have spares yet. Although with the rest of the system on full chat they are only using about 50% of the rated power from what I can tell.
Just a passing note that comparing amplifiers can be tricky: you might well have been "down in the noise" of your PA amp, and pushing another 10dB of level may well have helped a lot. Of course, that risks clipping the smaller amplifier, and/or destroying your HiFi speakers.
If you're looking for 4x amplifier channels, excellent audio quality and extensive limiters, I'd recommend a Powersoft T304. I've used a T604 to bi-amp a pair of BMS 4592s for a HiFi show, and that combination worked well, even though the amp never exceeded a couple of volts on the output.
Chris
If you're looking for 4x amplifier channels, excellent audio quality and extensive limiters, I'd recommend a Powersoft T304. I've used a T604 to bi-amp a pair of BMS 4592s for a HiFi show, and that combination worked well, even though the amp never exceeded a couple of volts on the output.
Chris
Fair point Chris. It wasn't at a very loud level at all the PA amp was on about -40db to get the same perceived output level as the cambridge power amp. I can easily try it again and pump it (Id set the limiter on the power amp to about 110rms anyway, so it couldnt accidentally fry the hihfi speaker, they can take 140rms from the cambridge amp OK). The problem with doing a louder test is the room acoustics are utter shite and will overpower the ability to hear the music properly. Might try that anyway and see what happens
Yes I have considered the powersoft, they arent too expensive. Maybe if I come to yours for some more tuning work I could compare with my amp if I were to bring one along?
Yes I have considered the powersoft, they arent too expensive. Maybe if I come to yours for some more tuning work I could compare with my amp if I were to bring one along?