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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.
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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
elliottbnewcombjr OP
5,103 posts
 
three_easy_payments

thanks, we agree about the video and advantages of 16 ohm reduced distortion.

In the beginning, when 4 ohm speakers showed up, some sounded very good, however they were small enclosures, and it seemed to me they needed a heck of a lot of power, the complete opposite of my goals. I didn't know about amount of distortion involved.

I encourage trying tube amps, and the way to save money/size/heat/cost of tube rolling/replacing, is to start with efficient speakers, thus you can stay in the 35/30/25 wpc world of tubes, even less if you use horn speakers or other highly efficient speakers. My friends system uses 8 wpc tube amps.

I remodeled my office recently, my friend has an unused pair of KEF's, I remember them sounding great, I was going to use my Carver Cube 200wpc, enough power for them. However they are 15" deep (to get more box volume, avoiding port(s) I suppose), sadly too deep for bookshelf use.
elliottbnewcombjr OP
5,103 posts
 

charles1dad

Thanks for your reinforcement of Ralph and other's comments.

I knew the speakers were very high efficiency (horns), and needed little power (16 ohms is easier, I knew that), but I was unaware of the inherent advantages to the amp regarding lower distortion.
clio09
3,342 posts
 
Roger Modjeski always recommended "light loading" his amps and gave numerous reasons why this was beneficial. Some were mentioned by @atmasphere in a previous post. On a pair of 8 ohm speakers I run my RM10 off the 4 ohm tap. The difference is very noticeable versus the 8 ohm tap. Roger often opined why 16 ohms speakers went out of style. Oddly enough in cleaning things up around Roger's shop I ran across a set of Chartwell speakers that are 15 ohms. Going to give them a try on my RM10.
lewm
12,445 posts
 
I am not sure that generalization (16 ohms = lower amplifier distortion) would apply to every variety of solid state amplifier. Tube amplifiers as a class tend to have a much higher output impedance than do solid state amplifiers.  This does give an advantage for 16 ohm speakers. What I abhor about "4-ohm" speakers is that they tend to be multi-driver arrays with very complex crossover networks.  This is a set-up for low input impedance and for power-sucking crossovers.  You can get a Pass or other high quality solid state amplifier to drive these beasts because they generally have an output impedance well below 0.5 ohms, and there will be some listeners who like the results.  Speaking only for myself, I never have.  But it is wise to think about the speaker first, and then to choose an amplifier well suited to driving it.  Once that process is done, I have always tended to prefer at least modestly efficient speakers with high input impedance that can be driven by tube amplifiers (my preference has always been for OTLs) or low power Class A solid state amplifiers.  Not everyone will agree, and that's fine.

Don't forget to get rid of those "rheostats", which are probably L Pads.  L pads sound terrible and one is always better off without them. Replace them with discrete resistors or no resistance at all. See my earlier post.
elliottbnewcombjr OP
5,103 posts
 
McIntosh Speaker Wire Gauge/Distance/Resistance Chart (pdf pg 6)

http://akdatabase.com/AKview/albums/userpics/10004/MC2250%20Owners.pdf

Indicates: any given gauge: 8 ohm load allows double the length of a 4 ohm load. Presumably 16 ohm load would allow twice the 8 ohm allowable length (4 times allowable 4 ohm length).

I have to believe many if not most are using larger gauge than needed, however, some with 4 ohm speakers that dip to 2 .. some people might not be using a large enough gauge. And people are overly concerned about long speaker cables.

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Text from my MC 2250’s manual:

"Selection of the proper gauge wire to connect the loudspeakers to the amplifier preserves the quality of sound reproduction for which the loudspeakers have been designed. If undersize wire is used, resistance is added to the amplifier/loudspeaker combination which adversely affects the performance. Added resistance causes depreciation of damping characteristics, modification of frequency response and reduction in power to the loudspeaker.

Use lamp cord or wire with similar insulation to connect the speakers to the amplifier. In all cases, the leads to and from the speaker should be twin parallel conductor or twisted pair.

When using 8 ohm speakers and for the normally short distances of under 30 feet between the amplifier and speaker, #18 wire or larger can be used.

For distances over 30 feet a larger diameter wire is required. Select the correct size from the chart below. The DC resistance of the speaker leads should be less than 5% of the speaker impedance. Resistance of the leads must be computed for the length of wire both to and from the speaker or speakers.

Wire lengths above represent the wire resistance equal to 5% of the speaker impedance. For multiple speaker operation, run separate leads from the amplifier to the speakers."


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