This is a DIY HPF for non-commercial use. The project consists of a shared PCB which can be purchased through OshPark and the documentation you see here.
I designed this rumble filter to protect my speakers after I blew out a rather expensive woofer (ScanSpeak 26W/8867T) in my ESL hybrid speakers. I bi-amp with a XO frequency at 300Hz; the low side is DC coupled to a Carver TFM-55 (250 WPC) which is directly connected to the woofer. After changing cartridges (Sumiko BlackBird), the tonearm/cart would produce a rather nasty oscillation on warped records at approximately 10Hz and high enough amplitude that the cones would almost leap out of their frames. After installing the HPF between the electronic XO output and the Carver input, the speaker cones behave as if I'm listening to a CD rather than a warped record. There is no loss of bass and no apparent sonic penalty to using the filter.
The filter is an 8 pole HPF with Butterworth response and unity gain. It uses a pair of OPA-4134 quad opamps (one for each channel L/R) and a separate ±9VDC power supply that enters the PCB on the 3.5mm stereo connector. The filter has the following response:
24Hz -0.1dB
20Hz -0.8dB
18Hz -3dB
10Hz -42dB
5Hz -90dB
The simulation plot and actual measurement plots are attached.
You can purchase the PCB as a shared project at: [url]https://www.oshpark.com/shared_projects/ltF1TyFP[/URL]
The attached BOM file lists all the parts needed to build this project. The 16 capacitors are all Wima 220nF 5% Polypropylene, PN MKP2D032201K00JSSD. The RA RCA jacks are Kobicon PN 161-4220E. The 3.5mm jack is a Kobicon PN 161-4033E. All the resistors are 0805 SMT types. These parts are all available at Mouser, Digikey or other on-line suppilers.
The PCB is 3.25" x 2.325". Power on the 3.5mm jack is -9V/+9V/Gnd (Tip/Ring/Sleeve).
I designed this rumble filter to protect my speakers after I blew out a rather expensive woofer (ScanSpeak 26W/8867T) in my ESL hybrid speakers. I bi-amp with a XO frequency at 300Hz; the low side is DC coupled to a Carver TFM-55 (250 WPC) which is directly connected to the woofer. After changing cartridges (Sumiko BlackBird), the tonearm/cart would produce a rather nasty oscillation on warped records at approximately 10Hz and high enough amplitude that the cones would almost leap out of their frames. After installing the HPF between the electronic XO output and the Carver input, the speaker cones behave as if I'm listening to a CD rather than a warped record. There is no loss of bass and no apparent sonic penalty to using the filter.
The filter is an 8 pole HPF with Butterworth response and unity gain. It uses a pair of OPA-4134 quad opamps (one for each channel L/R) and a separate ±9VDC power supply that enters the PCB on the 3.5mm stereo connector. The filter has the following response:
24Hz -0.1dB
20Hz -0.8dB
18Hz -3dB
10Hz -42dB
5Hz -90dB
The simulation plot and actual measurement plots are attached.
You can purchase the PCB as a shared project at: [url]https://www.oshpark.com/shared_projects/ltF1TyFP[/URL]
The attached BOM file lists all the parts needed to build this project. The 16 capacitors are all Wima 220nF 5% Polypropylene, PN MKP2D032201K00JSSD. The RA RCA jacks are Kobicon PN 161-4220E. The 3.5mm jack is a Kobicon PN 161-4033E. All the resistors are 0805 SMT types. These parts are all available at Mouser, Digikey or other on-line suppilers.
The PCB is 3.25" x 2.325". Power on the 3.5mm jack is -9V/+9V/Gnd (Tip/Ring/Sleeve).
Attachments
Wasn't a problem for me. I made the connection before applying power to the cable. Also, ground is the last connection to make contact so I don't think there is a DC path established until the connector is fully inserted.
If this is a concern, then leave the connector off and hardwire the power connections.
