Dominick22 said:
Dominick,
Back in the bad old days of tubes there were many speakers that had higher Ohm specs, 16 ohms wasn't all that unusual. My focused arrays are series/parallel wired and measure 9.9 Ohms across the terminals. I have a LM4780 chip amp (a custom job by Kevin Haskins) and these sound very good indeed. At the Seattle DIY Meet held at Adire last October, we used the 4780 in the upstairs room for most of the day and none of the builders requested a change to another amp. I really don't see any advantage to any speaker over 8 Ohms, at least with SS amps. With Tubes, YMMV.
Best Regards,
TerryO
Once upon a time, Phillips made, I believe, an 800ohm (!) 12" wide-range / full-range driver. It was mentioned on the Single Driver Site when Herbert Jeschke stuffed some into a pair of 8" tall 'Voigt Pipes' (P.G.A.H. Voigt must be spinning in his grave -see here if you want to look at them: to be fair, thy certainly look impressive! http://melhuish.org/audio/oswaldsmill.html).
Now, I take that value with about a ton of salt, but you get the idea. The original, legendary BBC LS3/5a was nominally rated at 15ohms; it's computer-optimised second varient (which Harbeth reckon really should have been called the LS3/5b, so many changes were made) was rated at 11ohms. So yes, indeed you can get higher. 8ohms is the most common, though that doesn't necessarily mean they will be!
Best
Scott
Now, I take that value with about a ton of salt, but you get the idea. The original, legendary BBC LS3/5a was nominally rated at 15ohms; it's computer-optimised second varient (which Harbeth reckon really should have been called the LS3/5b, so many changes were made) was rated at 11ohms. So yes, indeed you can get higher. 8ohms is the most common, though that doesn't necessarily mean they will be!
Best
Scott
The worst driver I ever came across was a big, 10" bextrene job from 1976 or thereabouts I think. 12ohm, 82db sensitivity, and about as rigid as a politician's morals. The sound... well, you know the frequent complaint about plastic cones was that they 'quacked'? This thing sounded like a country pond full of mallards. Needed 200wpc to say boo to a goose (or another duck for that matter.) Unutterably vile.
Douglas Self shows in his "Power Amplifier Handbook" that for a typical bipolar transistor power amplifier, distortion driving a 4 Ohm load is higher than driving an 8 Ohm load. Using his argument, a 16 Ohm load would further reduce distortion (it's all about current). However, transistor amplifiers are voltage sources, so if a loudspeaker manufacturer makes their loudspeaker 4 Ohm rather than 8 Ohm they gain 3dB of apparent sensitivity. That's why most modern loudspeakers are 4 Ohm. Conversely, the 11 Ohm LS3/5a loses out even further...
If we used 16 Ohm loudspeakers, we could get away with thinner loudspeaker cables.
As previously mentioned, valve OTLs have a heart attack when faced with loads < 16 Ohm.
Valve amplifiers with output transformers don't really mind whether it's 4 Ohm, 8 Ohm or 16 Ohm (provided their output transformer can be configured correctly).
If we used 16 Ohm loudspeakers, we could get away with thinner loudspeaker cables.
As previously mentioned, valve OTLs have a heart attack when faced with loads < 16 Ohm.
Valve amplifiers with output transformers don't really mind whether it's 4 Ohm, 8 Ohm or 16 Ohm (provided their output transformer can be configured correctly).
Scottmoose
That figure you quote for a Phillips speaker is not far out from memory. They called it Hi-Z, made a number of different driver sizes, and used it in mains transformerless valved amplifiers and TV's. Lethal items that would kill any unwary serviceman. Valve filaments were in series, and the mains directly rectified. The chassis had to be totally insulated to protect users, but this was poorly done, and any cabinet damage could turn them into a death trap.
That figure you quote for a Phillips speaker is not far out from memory. They called it Hi-Z, made a number of different driver sizes, and used it in mains transformerless valved amplifiers and TV's. Lethal items that would kill any unwary serviceman. Valve filaments were in series, and the mains directly rectified. The chassis had to be totally insulated to protect users, but this was poorly done, and any cabinet damage could turn them into a death trap.
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