Hi Edlartford,
I don't have any dual voice coil drivers on hand. But you are right, that would probably remove all significant variables from the comparison between 4, 8, and 16 ohm formats. Unfortunately, I'm not nearly curious enough to buy a dual voice coil driver or two just for the experiment.
Cheers,
Duke |
Audiokinesis.... Transformer taps are another issue. How about experimenting with a driver that has a split (dual) voice coil, that you can hook up in series or in parallel. This would take just about everything out of the comparison except the voice coil impedance. |
Hi Eldartford,
You're right that I made a lot of changes in that system as described, but I didn't give all the details of what I did. I used a Nakamichi active crossover in comparing the 4 ohm and 16 ohm configurations, which took the passive crossover parts out of the equation and levelled the playing field quite a bit more. But I had to build the passive 16-ohm crossover to see if it would sound better than my (optimized) passive 4-ohm crossover, which I'd tweaked to sound better than the generic second order active filter.
Later on I built a subwoofer and once again found the 16-ohm configuration to sound better (tighter), presumably due to the amp's higher damping factor into the higher impedance load. In this case, I did miss the extra headroom that the 4-ohm configuration gave me over the 16-ohm configuration.
In both of these examples, I was using relatively cheap solid state amplification, so the trend may not hold up for better quality amplifiers.
Recently I did a fair amount of experimenting in the course of designing a homebrew speaker system to work well with my parents' little JoLida tube amplifier. In this case, I found that a 16-ohm speaker driven off the 4-ohm taps sounded the best (I experimentd with 4, 8, and 16 ohm versions of the speaker using either one or two small full-range drivers). The differences between the different speaker impedances were somewhat subtle, but the difference between the 4 and 8 ohm taps on the amp was obvious and dramatic. That being said, I am not claiming that the 4 ohm taps will necessarily sound best in anyone else's system - but they sure did in this one.
Duke |
My Dad's KLH Model 1 bass drivers/Janszen electrostats are 16 ohm. They do indeed sound better and are easier to drive with his 40Watt Citations vintage amps or with his McIntosh 2105 SS amp run on the 16ohm tap (autoformer)..His Krell KST100 although more powerful is not the best match for those speakers. Dont play as loud and actually have less bass with the Krell. |
Gregm...A third advantage of 16 (or 32) ohm speakers is that lower gauge speaker wire can be used. This is a big factor if you are running 100 feet or more for some kind of a public performance, but would also apply to shorter audiophile cables. |
Audiokinesis...You made a bunch of changes to your speaker system, so it's not definite that the improvement was due to the amp performing better with higher impedance. My review of amp specs shows that 4 ohm and 8 ohm distortion specs are the same, but 2 ohm specs (where the amp can do this) are usually degraded. |
Even with solid state amps that put out more power into lower impedance loads, sometimes you get better sound driving a higher impedance load. I remember years ago building a homebrew that had two woofers, which of course I wired in parallel. Just for fun one day I wired the woofers in series on one of the speakers, scaling the crossover components accordingly and padding the tweeter way down to match sensitivities. Adjusting for equal volume, the 16-ohm version sounded better on my inexpensive NAD integrated amp than the 4-ohm version did. The sound was more effortless is my recollection (that was over 20 years ago). For some reason (better damping factor maybe) that particular solid-state amplifer sounded better driving a high impedance load. Since I didn't listen very loud and didn't need the extra headroom, I converted the other speaker to 16-ohm configuration and left them that way until the speakerbuilding bug bit me again a few months later.
Duke |
Eldartford above, beat me to posting the second advantage of 16ohm drivers. Twl explained the first one:). Cheers |
Compared with and 8 ohm speaker, a 16 ohm speaker requires that the amplifier put out twice the VOLTS for a given power, because it draws half the amps. Solid state amps are limited by the volts they can output...within reason (and until a fuse pops) they can hold up this voltage regardless of the current drawn. Thus their wattage rating increases for lower impedance speakers. Tubes have high voltage capability, but can output little current, therefore tubes are usually interfaced using a step-down transformer which trades off voltage for current. This transformer has different taps (connection points) on its secondary winding so as to match different speaker impedances, so that the amp will work equally well with any impedance.
In the non-audiophile world, where solid state amps reign, 16 ohm speakers have the advantage that you can hook four of them up in parallel, and still have only a 4 ohm load. |
The advantage to me is that my favorite speaker to date is 16 ohm (my Tonian lab TLM-1's) As stated above... TWL and Jeffeybehr have it right.
If someone else's favorite is 4ohm... great! |
Snofun3: "Ohm rating is not an indication of goodness or badness, it's a measure of driver efficiency.
A 16 ohm speaker will take more amp power to drive."
Right, wrong, and wrong.
Absolutely, nominal impedance is NOT a qualitative measure of a speaker system.
System impedance is NOT an indicator of speaker-system efficiency or sensitivity.
High-impedance systems generally consume LESS amplifier power.
I think Twl correctly stated the meaningful differences.
. |
Pros: They work well with tube amps that have high output impedances. Especially most OTL types.
Cons: They will not play as loud with solid state amps that have lower power output into a high impedance load. |
Ohm rating is not an indication of goodness or badness, it's a measure of driver efficiency.
A 16 ohm speaker will take more amp power to drive. |
