Edcor OPT's multiple taps

[Moonwatcher]

Hello, all,

I have Edcor ouput transformers, model CXPP25-8K (I think), on a Maggie 9300 series amp. Does anyone know if it is possible, or possibly harmful, to use both the 4 ohm and 8 ohm taps simultaneously on two sets of speakers? I'm hoping to get the strong and velvety mids from early Wharfedales (8 ohms, sort of) and the deep bass from a pair of Smaller Advents (4, sort of). Thanks!

 

[RWood]

No, I am afraid it is an “either-or” situation. You can certainly compare one and then the other but they cannot safely be run together.

Those must be big transformers if 25W.

 

[Moonwatcher]

Well . But thanks; I appreciate the warning.

 

[GordonW]

If the speakers were 8 and 16 ohms- then, you could put the 8 ohm speakers on the 4 ohm taps, and the 16 ohm speakers on the 8 ohm taps, and each would get half-power- the amp would still see the correct total load.

However- no, there is no way to do that with a 4 ohm and an 8 ohm speaker, unless the amp had a 2 ohm and a 4 ohm tap.

Regards,
Gordon.

 

[Moonwatcher]

I see, Gordon, thanks. Is there any way I could wire resistors in series with the speakers to make it work? Say 4 ohms in series with the 4 ohm speaker and 8 in series with the 8 ohm speaker?

 

[GordonW]

Resistors would waste half the amp power, and probably cause the bass to be boomy and uncontrolled, due to the lack of damping factor.

Regards,
Gordon.

 

[Moonwatcher]

OK, thanks. I've also tried just running the Wharfedales on the Maggie and the Smaller Advents on the Marantz 2230, and it's quite lush--if maybe not quite as dimensional. Co-amping with solid state and tubes is pretty unconventional, I guess.