Fs. PHY HP 21LB15 Alnico drive units.

[Monty]

PHY HP 21 Alnico drive units.

Bought these about 15 years ago from GT Audio, when they were the agent for PHY in the UK.

I have used them, but they have spent a lot of time stored.

8 inch very high efficiency, 15 Ohm voice coils with Alnico magnets.

They are used in some very expensive exotic speaker systems.

Asking £900 for the pair. Collection preferred, but will ship at your cost and risk.




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[bumpy]

Such a shame. Had they been 8 ohm I would have been all over them. Good luck, and have a bounce on me.

[spendorman]

Such a shame. Had they been 8 ohm I would have been all over them. Good luck, and have a bounce on me.

What's wrong with 15 Ohm, apart for appearing a little less sensitive, just gives the amplifier an easy time?

[bumpy]

What's wrong with 15 Ohm, apart for appearing a little less sensitive, just gives the amplifier an easy time?

I have a perfectly balanced set of 3 way open baffles where all the drivers are 5 to 8 ohms, alnico magnets and paper cones. Crossovers are passive. I have had a lot of pleasure in trying alternative mid range drivers. I am careful to select only 8 ohm drivers so they can be substituted without great drama. I suspect that putting in a 15 ohm driver would require too many fundamental changes.

[spendorman]

I have a perfectly balanced set of 3 way open baffles where all the drivers are 5 to 8 ohms, alnico magnets and paper cones. Crossovers are passive. I have had a lot of pleasure in trying alternative mid range drivers. I am careful to select only 8 ohm drivers so they can be substituted without great drama. I suspect that putting in a 15 ohm driver would require too many fundamental changes.

A point yes, I use Rogers Monitor LS3/6 speakers, the three drive units have various impedances. For example, the tweeter is 16 Ohm and the supertweeter is in excess of 23 Ohms.

[bumpy]

[sailor]

Hi Chris,

If your XO is set up for an 8 ohm driver and you replace it with a 15/16 ohm driver the XO point will halve.

To get back to the original XO point, simply change the capacitor for one that is half the value of the one being used. That is for a first-order XO slope. If a second-order slope is in place, then the inductor value would require doubling.
Holds true for 3rd and 4th order XOs as well.

In many designs, manufacturers choose to use 4 ohm units because for the same XO point the values go in the opposite direction. That means a cap twice the value and inductor half the value is required. With the price of copper a smaller coil is money saved.

If the driver you are really keen on is a different impedance it is perfectly OK to use it, providing you make the changes mentioned. I am sure that when you audition other drive units the sensitivities are different which requires tweaking the resistors.

Now if your existing XO is beautifully built using very expensive caps, then I would balk at hacking into it. In that case stay with 8 ohm

[bumpy]

Now if your existing XO is beautifully built using very expensive caps, then I would balk at hacking into it. In that case stay with 8 ohm.

Nail on head, but I'm trying hard not to take over this 'for sale' advert But it does get free bounces.

[hornucopia]

THese speakers are very special. They -in my Ocellia Calliopes - creat a lovely sense of imagery, and wonderful impact. These will be Furon made, so collectable.
https://6moons.com/audioreviews/ocellia5/1.html

[Monty]

Still available.

They measure 12.9 Ohm DC each unit.