I've been exploring the idea of building fully integrated active tower speakers using Hypex plate amplifiers. I've been driving the subwoofer section lately with a Drivecore XLS2500 amp, with Dual 15" RSS390HF-4's in parallel (2 ohm load). In this configuration, I require between 600 and 1000 watts to meet my needs.
The Hypex FA503 offers 500W + 500W + 100W, which seems like a good candidate. My plan is to:
The Crown DriveCore XLS2500 claims a damping factor of >200 at 8 ohms (10-400Hz), which translates to an output impedance of 40mOhms, below 400Hz. In contrast, the Hypex amp has an output impedance of ~1mOhm (<1kHz).
I assume wiring resistance adds to the denominator to give DF = Load impedance / (amp output impedance + wiring resistance). My calculations follow:
The Hypex FA503 offers 500W + 500W + 100W, which seems like a good candidate. My plan is to:
- Use the two 500W channels to drive the dual 15" subs in my ripole (25-110Hz). (500W into 4Ohms, each channel)
- Use the remaining 100W channel to feed a 3-way passive crossover for the midbass, midrange, and tweeter section (110Hz-20kHz).
Power Requirements
I’ve conducted measurements on the upper 3-way drivers during extreme listening sessions (painfully loud) and found that they draw less than 50W. Based on this, I believe the 100W channel is sufficient for the 3-way.Pros/Cons of an Integrated Approach
Pros:- Cleaner appearance
- Higher damping factor
- Built-in DSP
- Remote control options
- Higher cost (I already have the DriveCore amp for the subs and several stereo amps for the 3-ways above).
Damping Factor: Does It Matter?
This brings me to my main question about damping factor. If ever there were an application where damping factor mattered, I would expect it to matter most on a Ripole, without any meaningful air spring restoring force acting on the cone.The Crown DriveCore XLS2500 claims a damping factor of >200 at 8 ohms (10-400Hz), which translates to an output impedance of 40mOhms, below 400Hz. In contrast, the Hypex amp has an output impedance of ~1mOhm (<1kHz).
I assume wiring resistance adds to the denominator to give DF = Load impedance / (amp output impedance + wiring resistance). My calculations follow:
- Integrated amps (Hypex): ~363 DF installed, assuming 2ft of 14ga cable (10mOhms for wiring, 1mOhm output impedance).
- External amps (Crown): ~22 DF installed, with 10ft of 14ga cable (50mOhms for wiring, 40mOhms output impedance).
My Questions:
- In the frequency range of 25-110Hz, would a damping factor difference of 22 vs. 363 produce an audible difference?
- What measurements could I run to visualize or quantify the potential audible differences?
- Is there a practical limit where damping factor improvements no longer translate into real-world benefits?
- Has anyone actually measured the output impedance of the DriveCore amps? (Delta load method?)
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Damping factor more a hoax than a reality. Numerous people have done the math by considering the resistances involved and you just can't go beyond 10 or so. (BTW, some folks actually favour curtailing the damping for better bass.)
Kind of like the diminished value of super brakes on your car when driving on ice. The damping factor still has to budge a cone assembly, and these get more massive by the year (esp when these speakers can handle big watts without melting). So to get reasonable damping, you really want a light weight cone assembly and a compelling magnet-motor.
Now there is an effective method (or variety of methods) of controlling the driver and it makes an enormous and immediately audible difference on drums, etc: motional feedback. Using voice coil feedback, the output impedance of your amp is not, say, .01 Ohms. It actually might measure -8 Ohms. THAT is damping.
Kind of like the diminished value of super brakes on your car when driving on ice. The damping factor still has to budge a cone assembly, and these get more massive by the year (esp when these speakers can handle big watts without melting). So to get reasonable damping, you really want a light weight cone assembly and a compelling magnet-motor.
Now there is an effective method (or variety of methods) of controlling the driver and it makes an enormous and immediately audible difference on drums, etc: motional feedback. Using voice coil feedback, the output impedance of your amp is not, say, .01 Ohms. It actually might measure -8 Ohms. THAT is damping.