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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.
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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

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thanks, Elliott











elliottbnewcombjr
lewm
13,162 posts
 
Elliot, What you say to Cisco (Cisgo) may be true for an SS amplifier but for a tube amplifier, especially a transformer coupled one, the reverse is more likely, for a given tap on the output transformer:  An amplifier that makes 12W into 8 ohms might make only 6W into 4 ohms.  This is not always the case, and actual measurement is in order.  Likewise, an SS amplifier is likely to double its power into 4 ohms vs 8 ohms, provided it can deliver the needed additional current, which depends upon the power transformer.  But Cisgo apparently owns a First Watt amplifier, designed by Nelson Pass, one of the best and most innovative of all designers of SS gear.  In the First Watt series, he is experimenting with different topologies and different types of output devices.  So if Cisgo's information about his own amplifier comes from NP, I would accept it as gospel.  And Cisgo, if you want to know why the power rating changes as you say, ask NP.
charles1dad's avatar
charles1dad
10,250 posts
 
I agree with lewm in that Nelson Pass used his First Watt designs to intentionally deviate from their siblings throughout the model line.
The J2 was designed as a single ended transistor amplifier using only 1 output power transistor per channel. Just as a SET amplifier utilizes only 1 output tube per channel.

So it makes sense that it will deliver less power into a lower impedance load if the circuit was optimized for an 8 ohm impedance speaker load. Some First Watt amplifiers are push pull and will behave differently. Basically whatever Nelson Pass was  trying to achieve with the given model. Each F.W. amplifier is quite distinct.
Charles
mijostyn's avatar
mijostyn
8,570 posts
 
That is wonderful to hear Raul as I will be driving my Sound Labs with JC-1s at least for the time being. Dr West also highly recommends Atma-Sphere MA2's. The newer units have undergone significant changes in their interfaces. They do suffer from the same anomaly my old Acoustats had. Both designers were intent on making the speakers full range but for some reason that has to with transformer physics it is impossible to make a single transformer cover the entire audible range gracefully so both designers decided to use two transformers and a blending network to do the job. In my case I am crossing over to subwoofers somewhere around 100 Hz (125 Hz with the Acoustats) So, I do not need a transformer to go down low. Consequently I can get away with one transformer and no complicated blending network. This worked great on the Acoustats. I'll live with the SoundLabs for while before I start screwing around with transformers. Lewm relates that he bypassed the bass and brilliance controls. Dr West assures me there is no benefit in doing this. If it is easily reversible I'll give it a try. I am not fond on any additional stuff in the signal path particularly if it is not doing anything useful. 
elliottbnewcombjr OP
5,526 posts
 
It's always interesting to learn things here. Of course I have heard of the highly respected Nelson Pass, but never checked anything out.
atmasphere's avatar
atmasphere
11,856 posts
 
It makes sense that only putting out half the power (vs 8 ohms) with the same power supply and current could relax an amp at times, but I suspect otherwise.
If you can find a solid state amplifier that makes more distortion into 16 ohms as opposed to 8 or 4, I'd be interested in hearing about it. Looking at hundreds of solid state amps over the years, I've not seen one.

The one pitfall that you might run into isn't related to the load impedance so much as it is the intention of the loudspeaker designer. If that designer was intending the speaker to be used with tubes (as is common with 16 ohm speakers) then the design could sound bright (less relaxed) in certain situations. This is certainly true of ESLs with solid state (but the brightness there is due to a low impedance at high frequencies, despite a high impedance at low frequencies).


@elliotnewcombjr 
Unless someone talks me out of it!!!

Be prepared to work with a variety of values if you really intend to remove the level controls! I'd leave them in place if I were you (I certainly have done so with my speakers). This is simply because the speaker is designed without foreknowledge of the voltage response of the amplifier (IOW its a Power Paradigm device), so the control is there to allow you to adjust it to match to the amplifier . One way this can cause an issue is if you run a really long speaker cable as opposed to a short one- it might require a different setting of the level control since the apparent voltage response of the amplifier will be affected by the speaker cable (in the case of a really long cable) in series with the amp. I personally stay away from long speaker cables as speaker cables have errors unrelated to their DC resistance, and these errors (due to something called 'characteristic impedance') get more profound with longer cables. So I run short speaker cables and long balanced interconnects to get around this issue, since balanced lines can be run some very long distances without coloration (if they are set up correctly).

Never really understood how it worked that way. Figured I’d jump into this one and see if anyone had a brief explanation, thanks. 

@cisgo  The J2 is current limited (helps keep the output device alive) and so power does not increase as the load impedance is reduced to 4 ohms. But because its output impedance is relatively low, its power output is dropping into loads above 8 ohms. This amp is best used with a higher efficiency speaker, and a 16 ohm speaker will allow it to behave as a voltage source as long as you don't overload it.
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