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16 ohm speakers: any amp sounds better with more resolution. speaker cables less critical.

First,
  
Thanks to anyone who responds with whatever answers/opinions/advice comes from this. I'm retired, covid bound, Donna is taking care of everything holiday related, too much time, always curious.
..................................

I happened across this in an old thread started by Ralph (atmasphere)

"Sixteen ohms, BTW is a very simple means for getting more resolution out of your system, as nearly every amplifier made sounds better on 16 ohms than it will on 4 or 8 ohms. Speaker cables become far less critical too."

My speakers are 16 ohms (Electrovoice horn tweeter, horn mid, 15" woofer, crossover, rheostats, from 1958).
Extremely efficient, I have more than enough power. Amp, now and in the past all had 16 ohm taps.
Of course I can hook them up to my Cayin's 8 ohm taps now and listen, but facts, opinions, advice, to learn is good.
...........................


Lots of Questions? 

1. why/how do 16 ohm speakers make amps sound better, with more resolution? 

2. why speaker cables less critical? perhaps this is why I/we don't hear cable differences in my system?
I'm using my homemade twisted pair of cat 5 now (8 individually insulated small diameter solid core).

3.  to get exterior bias control: use 8 ohm tap for my 16 ohm speakers? (get alternate amp 4/8 no 16 tap,)

lose advantage(s)? 'sounds better'; 'more resolution'; 'speaker cables less critical'? 

this says slightly more mids:

http://blog.hughes-and-kettner.com/ohm-cooking-101-understanding-amps-speakers-and-impedance/

I can fine tune my speakers via their two rheostats: 'presence' and 'brilliance', so not really an issue for me.

4. Importance of Bias Control

how important is Bias? (I don't care about heat, power output, or tube life, just as bias affects sound). Frankly, using vintage tube receiver Fisher 500C, 800C and Fisher Mono Blocks 80Z, I have never checked or adjusted bias. I just put the control in the center position when cleaning insides/controls.

I have always used 16 ohm taps of various vintage tube and SS amps and newer current tube Cayin A88T. (original version, the only one with 16 ohm taps). It's bias control is internal, versions with safer external bias do not have 16 ohm taps.

5. replace their two rheostats? ('presence' and 'brilliance': copper wire-wound on ceramic body, mid/neutral position).
I have them in neutral position now, l/r frequency response equal.   

do I need to keep rheostats 16 ohms? use 8 ohm rheostat with 16 ohm drivers?

sales sheet says 16 ohm, but data sheet shows range 1.0 to 5k ohms. 

https://www.mouser.com/datasheet/2/303/controls_rheostats-1228697.pdf

does that mean, the drivers will draw whatever they draw (varies thru frequency range anyway), doesn't matter as long as rheostat range starts 1.0 ohm, extends past say 100.0 ohms?

https://www.mouser.com/datasheet/2/303/controls_rheostats-1228697.pdf

...........................................


thanks, Elliott











elliottbnewcombjr
millercarbon's avatar
millercarbon
12,531 posts
 
1. why/how do 16 ohm speakers make amps sound better, with more resolution?

They don't. It does change the sound and in making it more lean and etchy it can seem to be more detailed. Its not. 

Because of the way they are wired its very easy for Eric Alexander to make his Tekton Moabs in either 8 ohm or 4 ohm. Everyone following the advice you mentioned told me to order 8 ohms. It will be so much better. Especially since I have a tube amp. They made all the same technical arguments you have undoubtedly heard. I talked with Eric and went with 4 ohms. Hard to imagine how these speakers could be any better.  

But if you want stories, here is the antidote to the 16 ohm story: 
https://www.youtube.com/watch?v=tMAO9LPsups  

2. why speaker cables less critical? perhaps this is why I/we don't hear cable differences in my system?  

We have no idea why you don't hear differences in your system. Could be the wires you are comparing are so similar the differences are so small its too hard to hear. The differences are there, guaranteed. My first experiment was with ordinary 14 gauge lamp cord, two runs shotgun vs one. Not much difference but it was there. Everything from that point on has been orders of magnitude greater and easier to hear. So its there, just waiting on you to find it. 
I'm using my homemade twisted pair of cat 5 now (8 individually insulated small diameter solid core).
The good news is this is so far down the scale you have nowhere to go but up.
Forget impedance. Forget construction. Focus on sound quality.

mijostyn's avatar
mijostyn
8,492 posts
 
Hi Elliot,
The "rheostat" has nothing to do with the impedance of the speaker. It is just a potentiometer that varies the amount of power going to either the tweeter or midrange horns.
16 Ohm speakers are more efficient. Not much current is required to drive them so heavy gauge speaker wire is not necessary. But, the wire you are using probably has high inductance. You should use 18 gauge wire that is a jacketed twisted pair like this, https://www.parts-express.com/belden-6300ue-18-awg-2c-cable-plenum-rated-in-wall-speaker-wire-100-ft...
Always use the 16 ohm tap. If you do not have one the 8 ohm tap will do. 
chakster's avatar
chakster
6,144 posts
 
My speakers are 16 Ohm (Zu Audio Druid).

There is a simple trick recommended by Nelson Pass (First Watt):

Put 160 Ohm (5w) resistor across the cable terminals on the speaker.
Some reviewers love it with 16 Ohm speakers.


atmasphere's avatar
atmasphere
11,756 posts
 
They don't. It does change the sound and in making it more lean and etchy it can seem to be more detailed. Its not.
This isn't how it works.

What's going on is how the amp interfaces with the speaker, how the amp behaves when its driving a higher impedance.


And how the amp behaves is that it will make less distortion, and this will be heard as 'more relaxed more detail'; IOW neither 'lean' or 'etchy'; quite the opposite.


A tube amp will make less distortion (assuming that it has a 16 ohm tap if using an output transformer) and so will have less of the lower ordered harmonics. In this way it will simply sound more neutral. Because there is less distortion, there will be less to mask detail.


A solid state amp tends to not have much of the lower ordered harmonics- their distortion signature tends to be more of the higher ordered variety. But again, they will make less of it, so they will sound sound smoother (since these harmonics are interpreted by the ear has brightness and harshness) and more detailed; the latter simply because there will be less distortion to mask detail.


So we see that in both cases we have the same benefit. Now if its between 4 ohms and 8 ohms, the 8 ohm solution will have lower distortion than the 4 ohm. Again, less distortion (though not as low as with 16 ohms). This BTW is easily seen in the specs of any amplifier. Being that we really are talking about high end audio, where the goal should be to get the music to sound as real as possible, lowering the distortion should be part of that solution :)

As far as the speaker cables go, its a simple fact that at 4 ohms, the DC resistance of the cable can play a role in the damping available to the speaker. The same speaker cable on a 16 ohm speaker is simply going to have a negligible effect on damping.


Now this depends largely on the assumption that the higher impedance speaker is simply higher impedance, and otherwise has the same breakups and other anomalies that it would have if 4 ohms or 8.


If your speaker has level controls or level adjustments, they are there for one reason only- the voltage response of the amplifier is unknown, and the control is there to allow the speaker to be adjusted to that voltage response. This is indicative of the speaker being built for amps that behave as power sources rather than voltage sources (for example, any tube amp that runs zero feedback). For more on this topic see:
http://www.atma-sphere.com/en/resources-paradigms-in-amplifier-design.html
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