Matching Speakers to amp


I currently own a PSA Stellar 300 paired with Focal Aria 926. I just picked up a used pair of Quad S-5 and I will be comparing the sound. I am not good a using technical specs to compare so I could use some help if anyone has the time to take a look at the amp & speaker specs below and give me some feedback I would greatly appreciate.
The basic question is: from a specification standpoint which speaker pairs up with the Stellar 300 best?


Stellar 300
Gain30.5dB +/-0.5dB Sensitivity for rated output power1.01V Noise1kHz@300 Watts <-100dB Input impedance S300Unbalanced 50KΩ
Balanced 100KΩ Input impedance M700Unbalanced 50KΩ
Balanced 100KΩ Output Impedance50Hz, 2.8VRMS <0.007Ω Damping factor50Hz. 2.8VRMS
8Ω >1100
4Ω >550 Frequency Response@2.8VRMS
10Hz – 20KHz +/- 0.5dB
10Hz – 50KHz +0.1/-3.0dB
Output PowerBoth channels driven 120vac mains, 1kHz, 1% THD 8Ω140W minimum 4Ω300W minimum 2Ω Stable for musical transients

Quad S-5
General description 3-way floorstanding speaker
Enclosure type ABR
Transducer complement 3-way ABR 165mm x3 Bass driver 165mm Woven Carbon fibre Cone x2
Midrange driver 125mm Woven Carbon fibre Cone Treble driver 12 x 45 mm
True Ribbon Sensitivity (2.83V @ 1m) 90dB
Recommended amplifier power 25-175W Peak SPL 112dB
Nominal impedance 6Ω
Minimum impedance 3.2Ω
Frequency response (+/-3dB) 42Hz ~ 23kHz Bass extension (-6dB) 35Hz Crossover frequency 570Hz & 3.2kHz

Focal 926
Speaker driversTwo 61/2" (16.5cm) Flax bass61/2" (16.5cm) Flax midrange1" (25mm) Al/Mg TNF inverted dome tweeterFrequency response (+/- 3dB)45Hz - 28kHzLow
frequency point - 6 dB37HzSensitivity (2.83V / 1m)91.5dBNominal impedance8 OhmsMinimum impedance2.9 OhmsRecommended amplifier power40 - 250WCrossover frequency290Hz / 2400Hz











jbuhl

Showing 5 responses by auxinput

@kosst_amojan - not entirely correct.  The major problems with driving low impedance loads (such as .5 ohm or 1 ohm) are the power supply.  Car audio is completely different because the power supply is a constant big 12V DC battery (and an alternater that continuously charges it).  There isn't usually that much of a power supply capacitor bank in car stereo amplifiers because it is being fed by DC. (you should know this).  Then it becomes a factor of designing the circuit so that it won't over-run based on the current requirements of such a low impedance - fed by a 12V DC power source.

With home audio, it's all based on A/C current, which only provides partial current in cycles of 50-60 hz.  Obviously, that's why we have huge capacitor banks in larger amplifiers.  The ability for the amp to drive low impedance loads is hugely dependant on size of transformer and capacitor bank (which you should know as well, based on your historical statements that you are very much an expert in analog electronics).

I have seen many Class AB amps in the car stereo industry that will run .5 or 1 ohm loads.  It is not limited only to Class D (however, there is definitely a large amount of Class D in the car stereo industry today).


Class D has its own fanbase, but the limitations on bandwidth due to the high switching in the circuit prevents it from really performing well in the ultra high frequency range and giving you that "air" and liveliness that Class AB amps provide.

The capacitors on that PS Audio 200c are likely so dried out they are failing to filter out the 60hz hum coming in from the A/C.  That could be why you get that hum.

I agree that the Rega is way too low power (only 60 watts?!?) for your speakers.  The Focal really perform best when you have a very high current amplifier (big power supply - high power).

The Steller S300 is probably only one of two Class D amps I would even consider (if I was considering) because of the Class  A input stage (the other one is Nord Acoustics).  However, if you are looking for an alternative, it is going to be really hard to get a good enough integrated (or amp) at the $500-600 level. 

The Parasound A23 above that George recommended could be nice, but it's only 125 watts per channel. 

Couple of things come to mind.  Parasound 2250v2 amplifier. Vincent SP331 amplifier (if you want a tube input stage).  Both are excellent.  Vincent has excellent bass response and voicing, but it does have a tube sonic signature (in case you are looking for pure solid state).  Both are currently on sale at Audio Advisor for $999.  Way above your budget, but these are just ideas.

If you want integrated, there are a couple of Yamaha S-801 integrateds on audiogon.  It's about the same power as Parasound A23


yes, but with the impedance challenges of the Focal and the fact that they usually sound thin/bright, I would think that you would want as hefty of a power supply as you could in the amp.  The A23 is nice, but definitely not a strong amp in the power supply section.
Hey George.  Yup, for those speakers I would probably pick the Parasound 2250 over the A23 (even though the A23 has XLR I puts and higher resolution), because of the larger power supply in 2250.  Also, the 2250 is no slouch either.

jbuhl, both the Rotel and outlaw are only about 120 or so watts.  I’m sure these or the Parasound A23 would play just fine, but still are somewhat light in the power supply for the Focal speakers.

theres an Odyssey Khartago on eBay with larger upgraded power supply, current bid $500.  I don’t know how high it will go, but this would be an excellent choice.
I would only recommend an Odyssey stereo amp if it had the power supply updgrade (which the one on ebay does).  The basic Odyssey Khartago only has 60,000uf capacitor bank (which is not much more than A23) and a small 400va transformer.