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S950 External Sound System

by Frank Jagdis
October 2013

The following is my personal journey in finding an amplification system for my PSR-S950. There are lots of opinions regarding amplification largely because sound is perceived uniquely by individuals. For this reason, what suits one may not suit another. The built-in amplifier / speaker system in the PSR range is good for personal monitoring. Professionals generally recommend spending an equal amount of money to purchase and amplification system. This may not be the best solution for home or casual users and those on a limited budget.


The Yamaha MS04 system is well matched for the Tyros line. It consists of two 20-watt satellite speakers and a 40-watt subwoofer. The Satellite speakers combine a ¾" dome tweeter with a 3" cone midrange. The sub has 6 ½" cone speaker. I have not found any information regarding using the MS04 with the PSR keyboards. I believe the connection plugs are unique.


The keyboard lineout of the PSR (and the TYROS) provides the input for amplifiers.


Today's keyboards produce a wide range of frequencies that require accurate reproduction. You can find nice graphs of the frequency range of musical instruments here. The piano and pipe organs can get down to below 30 Hz and at the upper end, strings and the human voice can get to 16kHz.

Here are the frequency ranges and characteristics for types of speakers:

Speaker Frequency Ranges
Tweater 6,000-20,000 Hz Brilliance associated with harmonics
Midrange 500 - 6,000 Hz Most of the sound for voices and instruments
Woofer 100 - 500 Hz The Bass sounds
Sub-woofer 20 - 100 Hz Bottom end beat to music – felt more than heard

You cannot chose speakers by looking at the frequency response stated by the manufacturer (see "Understanding Loudspeaker Frequency Response"). There is no substitute for listening. There are other variables such as the room acoustics which influence the quality of the sound heard.

Do you need a subwoofer? Lots of opinions here. My experience is that the bass is smoother, more natural and alive with a sub. Perhaps that's why subs are used with complete music systems (e.g Bose L1 Compact, Lucas Nano, Yamaha MS04, etc).


Like speakers, the world of amplifiers is equally complicated. I have been following the PSR Tutorial Forum (and others) for some years and seen many choices regarding amplification. I will not argue with the Bose fanboys. I concede, you win! The L1 Compact ($900-$1,000) has the best sound distribution. Some brave souls have dared to comment that the midrange is lacking and in mono the pianos sound "tinny". The solution is to buy the tonematch ($500) AND another L1 compact. This was beyond my budget.

I have seen statements about using the following systems: Home Hi-Fi, Home Theatre, Computer speakers, PA systems, Bass amplifiers, dedicated "Keyboard" amplifiers and lastly Pro-Amplifiers. There are portable PA systems such as Lucas Nano, Fishman solo Yamaha StagePas, Samson Expedition, Fender Passport, etc. However, there has been little user feedback. I did have a StagePas 300 but I found that it did not add much and the midrange was lacking.

I would be cautious of Bass amplifiers because the goal is different. Guitar amplifiers are out because of the distortion introduced. Home audiophile amplifiers can be good but can also be very expensive. With the exception of the Logitech Z5500 (no longer being made), I found the two computer speaker systems that I tried disappointing. Pro Amplifiers are the units you see on the rack of performing bands. I thought that if the bands can use them I should have a serious look. These are very powerful units in terms of wattage. They are primarily intended for use in large spaces.

Electronically speaking, amplifiers fall into a number of classes. Class A and AB are common in Pro Amplifiers. They have large power supplies, consume a lot of energy, and generate a lot of heat. For this reason fans are always built in. This is OK for a performing environment but may not be not OK for home or very small venue use.

Class D amplifiers are used in powered mixers and powered speakers. They are energy efficient and small. Most major Pro Amp manufacturers are now selling class D pro- amps. I believe that the electronic design is important but I am not an expert in this area. For that reason I would suggest staying with well known manufacturers. For information on how much wattage you need, check the article, "How Much Aplifier Power Do I Need".

Please pay attention to the wattage of the speakers. You can fry them if they are under-powered (clipping). The general rule is that amp output should be 1.6 times the speaker wattage rating per channel.


So what did I end up doing? Here is my current setup for a PSR S-950 for home use (I already had the last two items listed below) :

  • Crown XLS 100 Pro-Amp 215 watts per channel into 8 ohms ($325)
  • Behringer Xenyx 802 Mixer ($70)
  • (2) Kenwood 3 way speakers (10"woofer, 4.5" midrange, 2.5" tweeter)
  • Precision 10" 250 Watt SubWoofer

I send the mixer's control room (monitor out) to my sub-woofer amp and the mixer's main out to the Crown XLS. The mixer is not essential because the Crown has a line out but the setup allows me to add microphones and gives me finer control of the line signals.

I am very pleased with the sound that I get. It is full and I can hear all the instruments. The volume is exceptional. I have not heard the fan in this amplifier even after several hours use and to date the warning clip lights have not gone red.

For those interested here is an independent review of the Crown XLS series by an expert audiophile, check out "Review - Crown XLS DriveCore Series Amplifier" by Andrew Robinson. I find that the 1000 model gives me enough amplification with no noise or distortion. I hope others will find my experiences useful.

This page updated on September 5, 2015 .