I was wondering why 8 Ohms seems to be the starting point form resistance into a speaker?? Can there be a 10 Ohm or even higher Ohm speaker?
I was thinking that a speaker with a greater Ohm rating would be easier for my LM4780 amplifier to push??? Am I right?
Dominick in New Jersey
I was thinking that a speaker with a greater Ohm rating would be easier for my LM4780 amplifier to push??? Am I right?
Dominick in New Jersey
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
PHY-HP drivers are 16 Ohm. And as far as I know 16 Ohm (and high sensitivity) are essential for the 6C33 OTL (transformerless) amplifier concepts.
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
If you are interested in really bad drivers you can get a 750 Ohm Freischwinger from the thirties/ fourties. Probably they were only used to let Adolf sound rrrrrreally horrrrrrible.
😀 
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.
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.
Many early transistor radios were fitted with 25 - 35 Ohm speakers, to avoid the need for an output transformer. Academic really nowadays and in a Hi-Fi context🙄
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.
Shocking... 
😀
I bet the required number of windings in the driver made them nice and reliable too...
😀 I bet the required number of windings in the driver made them nice and reliable too...
EC8010 said:
Most modern speakers are 8 ohm, 4 ohm are pretty rare (although continental manufacturers tended to use 4 ohms), except for in-car speakers where you have a lack of voltage and 4 ohm is the norm.
Historically, in the valve days, most speakers were 16 ohm.
Depending on the manufacturer they can be 4 ohm, 6 ohm, or 8 ohm for home usage products. Most common.
Commercial applications can be 8 or 16 ohm as it is common to have either 8 or 16 ohm diaphrams for high frequency horns or a choice of 8 or 16 ohm low frequency drivers.
Commercial applications can be 8 or 16 ohm as it is common to have either 8 or 16 ohm diaphrams for high frequency horns or a choice of 8 or 16 ohm low frequency drivers.
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