Home » Sponsored » Pi Speakers » Pi Theater 4 driver replacement (B&C DE-250 in lieu of stock Eminence)
Pi Theater 4 driver replacement [message #97456] Sun, 25 February 2024 00:37 Go to next message
Groucho is currently offline  Groucho
Messages: 4
Registered: February 2024
Esquire
Hi Wayne,
As you suggested years ago, I would replace PSD2002 drivers with B&C DE-250 compression units. I found a pair of used DE-250-16 (16 Ohm model): can I adapt it with some mods on L-Pads? Thanks in advance!
Re: Pi Theater 4 driver replacement [message #97457 is a reply to message #97456] Sun, 25 February 2024 09:41 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18677
Registered: January 2001
Illuminati (33rd Degree)

You can, sure, but I'm not sure what values to tell you to use. The values for R1/R2 set the attenuation and also set the damping on the tweeter circuit, which has a large effect on the localized region near the crossover frequency. Too much damping and there's not enough output but too little damping and there's a peak at crossover. So you may or may not need to add a resistor in position Rs.

It's easier with 8Ω drivers 'cause the damping is the same as what the tweeter circuit was designed for. I even made a chart of R1/R2 values that maintained the right damping and provided attenuation at various levels in 2dB increments. But this chart can't be depended upon with other driver impedances.
Re: Pi Theater 4 driver replacement [message #97460 is a reply to message #97457] Mon, 26 February 2024 03:46 Go to previous messageGo to next message
Groucho is currently offline  Groucho
Messages: 4
Registered: February 2024
Esquire
Thanks,
Worth a try or better change the dome/coil with the 8 ohm type?
Re: Pi Theater 4 driver replacement [message #97461 is a reply to message #97460] Mon, 26 February 2024 08:42 Go to previous messageGo to next message
Wayne Parham is currently offline  Wayne Parham
Messages: 18677
Registered: January 2001
Illuminati (33rd Degree)

I would change the dome/coil assembly to an 8Ω part. To match the sensitivity, replace the 16Ω R1 series resistor value with 25Ω. Do this with series/parallel values of 20Ω and 30Ω, because those are regularly available resistor values.
Re: Pi Theater 4 driver replacement [message #97464 is a reply to message #97461] Tue, 27 February 2024 03:33 Go to previous message
Groucho is currently offline  Groucho
Messages: 4
Registered: February 2024
Esquire
Thank you. Will do
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