DSP Considerations

March 12, 2012
Digital Signal Processor Signal Path

I believe that using one good quality DSP is preferable to having all the components as separate analogue pieces.  There are arguments for the superiority of analogue sound.  I believe that given all the losses incurred by the cables and connectors required between the pieces, the potential for hum and noise between those pieces, the potential for errors in gain structure, the sheer amount of equipment required and the higher cost of the equivalent quality analogue equipment necessary to do the work of a good DSP, an all-analogue solution is highly impractical.

A top-quality DSP will provide a better overall solution with less chance for error, lower cost, lower noise floor and far greater flexibility and consistency thanks to its ability to recall settings.  Even if you could have a perfectly set and tuned analogue equipment rack, if one knob is bumped, or one potentiometer starts to fail, or one cable connection works loose, the entire signal chain is compromised and you have a huge task just to trouble-shoot and find the problem.  After that, you almost no chance of getting it back to exactly what it should be without a thorough re-calibration of the entire system.  With a DSP, there is a lot less to fail and the setting file can be saved both on the unit and on a computer drive.

If the DSP fails, the down-side is that the entire system is down, but the up-side is that the identical settings can be loaded on a new unit in minutes.  With a DSP-in-the-amps solution, you get the benefit of DSP consistency with multiple-processing redundancy – so if you lose one amp you still have a partially functional system.  With multiple DSP equipped amplifiers, the amps can be re-allocated and alternate settings loaded in minutes, bringing the critical components of the system back on line and properly protected so the show can go on.

So, if the amps have DSPs in them you have what is, in my opinion, the best overall solution.  I’ll add one caveat:  The amplifier and its DSP must be of high quality. Powersoft is of very high quality, but many people have based their opinions of Digital components based on experience with cheap, inferior equipment, which is why some people have a negative opinion of digital processors.

And as far as analogue to digital converters are concerned, a top-quality DSP has to have a top-quality A to D converter. Supplementing it for a separate A-D converter adds cost which might be put to better use by going to a better DSP that already has better A-D converters. When you’re at the level of splitting hairs over A-D converters, you must have already assembled the finest set of components possible, including the highest reference-grade loudspeakers and amplifiers, (with backups,) in order to be able to recognize and take advantage of the benefits that that type of change might offer.

Symetrix SSP Layout A

I would rather have two identical DSPs, one for backup, or spare DSP amps than the best-in-the-world DSP, A-D converters or analogue processing rack.  With the proper settings in a good quality DSP, the problems of blowing speakers can be essentially eliminated. Loudspeaker transducers are passive components and, barring defects, they will not fail unless damaged by the inappropriate application of power or by some physical abuse.  Amplifiers and DSPs have more potential avenues to failure and yet they are generally very reliable.  Like air crashes and car accidents, most loudspeaker failures are caused by operator error.  Many times the only error the operator makes is in believing the power-handling claims of the loudspeaker manufacturer, which leads to an error in understanding the limitations of the loudspeaker components.

Having a properly set-up DSP solution for your specific loudspeakers is the most important factor to consider to ensure their reliability. Details about how good the A-D converters are or whether analogue sounds better are valid points to ponder, but for those people whose business is providing sound, reliability, consistency and quality should be considered in that order.  All are equally important, but a failure of the first renders all other considerations moot.

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