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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
5,521 posts
 
L Pads are Staying!

Full on mid and full on tweet ((similar to removing them) was not good!

I messed about with them for quite a while. It is again clear to me that these speakers were designed with the control of mid to woofer and tweeter to mid in mind.

The center position is their designed default, then carefully adjust. Then, as I have said, getting L and R matched is not easy, but I have my methods and experience with them in different spaces/locations for 43 years, especially using McIntosh Mode control to move stereo/mono/l/r this way and that.

Next: Cassandra Wilson; Annie Lennox; Friday Night in San Fran 3 guitarists; Andreas Vollenweider; War of the Worlds. Rare Earth, Mickey Hart, Oscar Peterson.

The advantages are clear, they have sounded fabulous all these years, using the controls in the listening space is an asset, and as I age, as my/our high frequency hearing naturally diminishes, I will be able to boost the tweeter year by year.



lewm
13,159 posts
 
0.4V = 400mV, not 40mV
And 0.4V doesn’t make sense as a bias voltage for an amplifier output tube. It’s way too little. Also grid bias should read out as a negative voltage with respect to ground or with respect to cathode voltage.
atmasphere's avatar
atmasphere
11,851 posts
 
I messed about with them for quite a while. It is again clear to me that these speakers were designed with the control of mid to woofer and tweeter to mid in mind.
@eliottnewcombjr A little trick you can do is mark the correct position with a bit of tape. Then about once a month or so work the Lpads back and forth to clear corrosion, and reset them to the original level you marked.


BTW I'd be careful about using an analog mulitmeter when setting the bias on a newer amplifier (a vintage amp's bias procedure might expect that you are using a multimeter). A multimeter has a lower resistance than a DVM or VTVM (Vacuum Tube Volt Meter) and that can affect your reading a bit, how much depends on how high the voltage is (the higher the voltage, the more accurate they become) and the impedance of the circuit. Multimeters a nice to look at in a post-industrial world so to speak, but DVMs are actually easier to use and more accurate unless you get a junky one. If you want to use vintage stuff to do this task, get a VTVM and have it serviced out and calibrated.

lewm
13,159 posts
 
Ralph, I am not sure what you are saying, because the terms "multimeter" and "DVM" are so often conflated with one another.  VTVM is a clear acronym, because you are talking about a vacuum tube voltmeter.  But let's take my Fluke 87 meter.  It is a "multimeter" in the sense it can read DC and AC voltage, capacitance, DC and AC current, and it includes a diode checker.  But it is also a DVM in the sense it is digital and solid state.  On voltage settings, it offers 20Megohm resistance across the leads.  So, what is a "multimeter" and how do you distinguish it from a DVM?  Or, why isn't my Fluke a multimeter?  Folks like Elliot might benefit from this clarification even more than I. For sure, any respectable voltmeter can measure the -10V to -50V range of the grid bias voltage that is typically seen for most tube amplifier output tubes.
elliottbnewcombjr OP
5,521 posts
 
I made a nice long wooden screwdriver, but Steve's doing it the first time, it's an excuse to meet him.

I will bring my toy multimeter for him to throw in the trash or teach me how to use it for bias.
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