PHL Drivers for a Dipole

[ScottTracy]

I'm really interested in using PHL drivers for something just to see what they're like. I was thinking of using two 2410s (8" mid-bass) in series and getting valve output transformers made with 32 Ohm secondaries by Sowter for an EL34 amp, such as Morgan Jones' Bevois Valley or gingertube's Baby Huey. Can anyone tell me whether they think the PHL drivers will go low enough in an MTM setup in an open baffle dipole like Siegfied Linkwitz's Phoenix? They have a Fs of 72Hz and max excursion of +- 4mm.

Secondly, is there any point having a load resistance this high. I figure it should make the output transformer easier to make but would there be a noticable improvement?

Thirdly, the PHLs seem to have a fairly high Qms, I know very little about these things but I was hoping to drive the mids from a fairly high impedance to simulate true currrent drive, do the PHLs need a low source impedance to keep Qes and thus Qts low enough?

I realise changing a good design like the Phoenix with radically different drivers, a valve amp and intentionally high output impedance is just asking for trouble but do people see the idea of having any potential for its easy drivability and very low power requirements?

and then just for good measure can I ask why the PHLs aren't rated to go very low for there size? eg the 4550 is a 12" and is usable only down to 60Hz apparently.

Thanks

Iain

 

[EC8010]

Secondly, is there any point having a load resistance this high. I figure it should make the output transformer easier to make but would there be a noticeable improvement?

In theory there ought to be an improvement, in practice, the transformer manufacturers have had more experience with more standard loads. Do bear in mind that real loudspeakers are nothing like resistive loads.

 

[ttan98]

Refer to Martin King, Mathcad sheet to design dipole. It includes a section on dipole.