Cheap PA amps with DSP

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Looking at various PA amps, and after browsing a bit, I would really like an overview of amps following a specific set of criteria:

Low price (Under 250$/channel)
+
Low noise (better than 110db THD+N)
+
Built in DSP


Have not gotten very far, but I'll start a list with an entry and then update accordingly.

1. After a lot of looking around it seems that Sinbosan is the manufacturer of most 4ch DSP capable amps, the label on the box varies between Aoyue, Soundpaul and probably a lot more. Proper USB connection and actual software for DSP starts just under 700$ for 4 channels. Claims better than 110db S/N. Look for DSP-6Q.
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2. An amplifier called RF-8004 seems very similar to the first one, but can be had for 400$ each. Not very different from DSP-6Q.
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3. Plate amp DS21000 2 Channels DSP, Dante compatible and rated at 115db s/n! Excellent looking numbers! 280$ each, caveat : RS232 for config.
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4.Plate amp bigger brother, PFC41000, not Dante compatible, but 4 channels and USB for easier connectivity, similar audio performance. 470$ each.
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Hoping to get a long diversified list, please chime in people.
 
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I've looked at the t.amp Quadro 500 DSP quite a few times.
Some of the arguments against it are:
1u height = not much space for cooling, so small "angry" fans.
Only 95db THD+N

IMO the thing to beat would be the Crown XLS DriveCore series, they have around 100db THD+N measured by 3rd party, reasonably priced, value for money.

In the last few years, I have started looking more and more to noise figures when checking out various sound products, because one thing that is really annoying with high sensitivity speakers is noise or hiss. Signal to noise or even better THD+N figures also give a indication of what the actual precision or resolution properties are of the equipment.
Does not matter if it's using a 24bit dac and the signal to noise ratio is 95db it might as well be 16bit, no difference in resolution.
Higher signal to noise or THD+N rating (in general) can in many cases be an indication of actual signal resolution as well as some indication on quality of the circuits.

My current setup:
Source: Audient id4 measured by 3rd party to 115-116db(?) (don't remember where, but I did read an in depth test somewhere)
DSP: dB-Mark XCA24 with a rating of 118db.
Amp: img STA-2000D with a rating of 119db.

A few dbs may be lost for various reasons, but I expect the signal chain to be better than 113db S/N worst case scenario.
With these gadgets I can not discern any difference in signal quality from lowest volume to full volume, so I can leave the power amp at max volume and just use the id4 to adjust volume. If I replace any of the boxes with some equivalent but rated at 100db S/N it is very clearly audible, difference really is chocolate vs sh1t, instantly noise will appear, everyone can hear it easily.

Still, it would be nice to find more equipment that has good noise figures and at reasonable cost.
 
well put! I'd like some cheap but good DSP power amps my self, but I guess there aren't any yet. Maybe in a few years there is plenty in the second hand market, former top of the line products being sold before the latest thingamawidget... For now professional products seem to cost closer to thousand per channel, and are way too powerfull for home use. Output power seems cheaper than DSP, for some reason. Good design costs. Actually, the hypex fusion are very good at the price point, but I'd prefer rack mount gear ... I'll save few years and buy a professional product instead of cheap substitutes that end up being more expensive eventually :) Subscribed
 
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hypex fusion are very good at the price point

After looking at the hypex fusion plate amps, it seems to me they are not that much of an improvement over the Crown XLS Drivecore. The Drivecores are measured around 100-100.7db THD+N, and the Fusion kits at 102.5db THD+N. So there is a difference, but it does not seem like a whole lot. Drivecores are much cheaper, at least for me...

The Powersoft products seem very nice, even though they are relatively low priced for equally compareable products, they are still somewhat expensive, and THD+N seems to be around 113db which is quite good, but I would really like to see numbers around 116-119db in that price range to justify cost.

So much focus on energy efficiency and power ratings, but signal integrity is more or less forgotten.
No wonder people have a hard time discerning between 16bit and 24bit recordings when most sound systems have so limited resolution.
 
Sorry yeah I must have been thinking the fusion as a DSP amplifier product in general (features), not particularly for the THD+N, which your thread is all about... I should quit posting :)

Anyway the XLS Drivecore DSP seem to have only 24db/oct LR filters and nothing else (like other filter slopes, PEQ, delay)? So not much of a DSP in my book... CDi Drivecores have these, but they cost a lot more and not as good noise specks as with Powersoft T. Hopefully there is a product found with your criteria sooner than later!
 
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Yes, well here is a link to bit depth and quantization on wikipedia, it's quite informative.
Audio bit depth - Wikipedia

And if you're somewhat informed in regards to measured resolution of a dac in real life situations, you should be aware that relatively few 16 bit signal chains are able to produce the full 96db spectrum, keep in mind: "something is always lost". So mostly you'd end up with resolution equivalent of 14 or perhaps 15bits.

You can see this on 24bit dacs as well, if you look at very well implemented designs a good dac is able to reproduce equivalent to 18bits resolution (a vast improvement from full 16bits, four times more data!), a very few 24bit dacs can touch perhaps around 19-20bits but that is not common performance at all. Getting resolution equivalent of 19-20bits from a 24bit dac requires very high attention to detail during circuit layout and design.

I've been thinking for some time that looking at signals in pure db scale is perhaps not the best way of considering the signal resolution, since a recording will never sound like a real performance. That was until I started comparing theoretical resolution and it's relation to noise figures.

I am hoping that some of the 32bit dacs and modern pwm amplifier designs can start achieving performance equivalent to 22-24bits actual resolution, because I think we need around 130db dynamic range to start closing in on the gap between live music performance and the recording.

Even if manufacturers brag about 24bits 96khz it's still fairly irrellevant, since actual performance for most equipment has not changed that much since the late 90's.
Higher sample rates do have some benefits in terms of signal processing, but for storing audio I'd be happy with floating 32bit/48khz, since you'd loose about 8bits anyway (32bit float is commonly 24+8) you get actual 24bit resolution, and 32bits can actually be easier to process using modern computers since they're mostly 32 and 64bits and it would be easier to standardize. Keeping it at 48khz samplerate would help reduce filesize greatly and not make any discernible quality difference from higher samplerates, other than being more compatible with the most common 96khz used today (upsampling for signal processing).

But I really have no clue about this stuff, not very good at finer technical points myself, this is just what I have been able to gather from looking at numerous other sources and comparing the data. As well as a small modicum of personal experience with audio signal quality.
Feel free to critique, and if there's any suggestions for high performance amplifiers with DSP it would be nice to know about that as well.
 
I hear you loud and clear Tom, and like previously mentioned, higher samplerates have very distinct advantages for signal processing. But for storing music I see no advantage at all in using higher samplerates, waste of space, better to upsample during playback.

Likewise with the dithering, it is intended to improve low level detail with 16 bit recording, but if you have proper 24bit any advantage of dithering = 0.
I do find it somewhat amusing that 16bit dithered often seems to lack some detail at certain peaks, like intense cello passages. Definitely nicer for the lower intensity parts but you still have to sacrifice something.
 
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