PMA800DSP

Dayton Audio PMA800DSP 2-Way 800 Watt Plate Amplifier
Application Evaluation

 This document is an evaluation of the Dayton PMA800DSP Plate Amplifier for the application of DIY power speaker cabinets. When this product first was put on the market at the end of 2016, Dayton designed this with a 3000 Hz crossover. This was a no go with me because I have been focusing on an 800 Hz crossover point. Sometime after the beginning of 2017, while browsing one of my favorite site, I seen some additional PMA800DSP with different crossover points defined. WOW!!

Dayton now has this PMA800DSP plate amplifier in the original 3k Hz crossover with the additional models that have 2.5K, 2K, 1.5K and 1K Hz crossover points. Each crossover point has a purpose but my design goals are to only send the bass band (40-160Hz) range, upper bass (160-300Hz) and the lower midrange (300-800Hz) to my woofer for a 2 way system. My crossover point has been defined at 800 Hz that splits the defined lower midrange of 300-800Hz and the midrange at 800-2.5k. I guess that I can compromise and used the 1K version.

This Dayton Audio PMA800DSP uses the Class D technology and provides up to 800 watts of power with independent amplifiers for 600W for low frequencies and 200W for high frequencies both ratings at a 4 ohm load. Other features include a DSP equalizer presets, and internal protection against shorted speaker loads, thermal faults, and overload conditions.

The next thing is to match the speaker for this amplifier to get the maximum results. This is why this document was started to evaluate the parameter and define recommendations for the speakers to be used. Articles from EAW, Peavey and others recommend a rule of thumb as two times the RMS or Continuous power rating of the speaker. This is not a guarantee that you cannot damage your speaker. Because of this it is also recommended that peak limiter is used for all inputs to you speakers.

Since we are looking at the amplifier first, let’s reverse engineer this application. We have a 600 watt amplifier for the low frequency below 1k Hz with a load impedance of four ohms. The best I can do using the prominent manufactures of speakers include:

  • Eminence Kappa-15C 15″ Driver 4 Ohm – This a 15″ speaker 4 ohm load with a power handling 450 watts RMS / max of 900 watts. The frequency response is 63 to 2,800 Hz and a sensitivity of 98.1 dB 1W/1m.
  • Eminence Delta-12LFC 12″ Driver 4 Ohm – This a 12″ speaker 4 ohm load with a power handling 500 watts RMS / max of 1000 watts. The frequency response is 453 to 2,300 Hz and a sensitivity of 93.1 dB 1W/1m.

The specification that we are addressing at the moment is the 600 watts at 4 ohms. This is why the above two speakers were selected. This rule of thumb is only a WAG when sizing an amplifier. The better way to determine power requirements is to use the crown design tools (Amplifier Power Required) by providing the required loudspeaker to listener distance, the SPL at that distance, your loudspeaker sensitivity (1W/1M) and desired amplifier headroom which is typically 3dB. You can extract the calculation to use in a spreadsheet or use the Crown app at http://www.crownaudio.com/en/tools/calculators.

To use the 600 watt at 4 ohm load, use a four ohm speaker. My selection is the Eminence Delta Pro 12-450-4 because of the high sensitivity value to optimize the output. Calculation parameters and results are:

  • Available wattage = 600 watts @ 4 ohms
  • Speaker sensitivity = 97.4 dB SPL
  • Headroom = 3 dB
  • Required SPL 90 dB

Instead of looking for the required power for a specific distance, you can reverse engineer this to find how far a power amplifier with a given speaker sensitivity can provide at a distance for a given SPL requirement. With these parameters, this speaker can provide the required 90 dB at about 80 feet.

To summarize, let’s look at the results for given speaker sensitivities with all other variables as constants.

Amplifier power at 600 watt at 4 ohms using a 4 ohm speaker with the required SPL of 90 dB at the listening distance and a headroom of 3 dB. The results of required speaker sensitivity at a given distance in feet and meters.
Feet Meters SPLSpk
100 31 95.1
80 25 93.2
60 19 90.7
40 13 87.1
30 9 84.6

To use this amplifier with 300 watt at 8 ohm load, use a eight ohm speaker. My selection is the Peavey Sheffield Pro 1500 with a 98 dB sensitivity, the Peavey Sheffield Pro 1200 with a 96.3 dB sensitivity and the Peavey Pro 10 with a 94.3 dB sensitivity because of the high sensitivity value to optimize the output. Using the table below you can determine a ballpark value.

  • Peavey Sheffield Pro 1500 with a 98 dB sensitivity – 90 dB @ 100 foot
  • Peavey Sheffield Pro 1200 with a 96.3 dB sensitivity – 90 dB @ 80 foot
  • Peavey Pro 10 with a 94.3 dB sensitivity – 90 dB @ 65 foot
Feet Meters SPLSpk
100 31 98.2
80 25 96.2
60 19 93.7
40 13 90.2
30 9 87.7
Amplifier power at 300 watt at 8 ohms using a 8 ohm speaker with the required SPL of 90 dB at the listening distance and a headroom of 3 dB. The results of required speaker sensitivity at a given distance in feet and meters.

All of the selected speakers were carefully examined for this application that includes the speaker parameters as well as cost and the possible solutions that this plate amplifier can provide. In this evaluation, I am using only the sensitivity of the raw speaker. Once a speaker is loaded in to a speaker cabinet, this sensitivity will increase. In my case, my focus is on horn loading to increase the efficiency of the speakers by 5, 10 or even 15% meaning drastic improvement on the SPL response at 1W/1m.

The high frequency should not be a problem because it does not take much power to amplify the level of frequency. We will still do a quick review with a sample of the driver that I would use for this application.

The horn driver that I have been using with good look is the Pyle PDS221 that is rated at 150 watts RMS and 300 watts peak @ 8 ohms. My plan are to use two of these wired in parallel in a line array waveguide that will provide a 4 ohm load with the 200 watt @ 4 ohms. The results are:

  • 200 watt @ 4 ohms
  • Headroom of 3 dB
  • Drive sensitivity of 102 dB 1W/1M
  • Required 90 SPL for listening distance
  • Results in 125 foot @ 90 dB

This Dayton PMA800DSP Plate Amplifier is a good selection for a cost effective solution that I have been looking for to incorporate into some of speaker cabinet builds that I will do.

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