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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
elliottbnewcombjr OP
5,351 posts
 

atmasphere

thanks for your clarity of these issues. I'm sticking with 16 ohm tap.

remaining questions:

1. how importance is bias to sound? (I don't care about heat or tube life).

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2. speaker cable inductance ..... gauge ____ awg

mijostyn said

" the wire you are using probably has high inductance. You should use 18 gauge wire that is a jacketed twisted pair like this".

Guage: Cat 5 8 strands is 15 awg. Two Cat 5's, 16 strands, is 12 awg.

https://www.wirebarn.com/Combined-Wire-Gauge-Calculator_ep_42.html

I don't really understand inductance. If speakers are high efficiency (mine are), and I/you have more than enough power from the amp, speaker

3. equiv 15 awg, is inductance an issue?

Inductance (Back EMF) might increase amount of current needed, but

4. enough power: does it have any effect on the music's frequencies? 

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

atmasphere

Voltage/Current

I read and re-read your paper you linked,

http://www.atma-sphere.com/en/resources-paradigms-in-amplifier-design.html

quite interesting. The Tekton video about using 4 ohm in lieu 8 ohms, 'getting more volume from 4 ohm' plays directly into your distinction between sensitivity and efficiency, which I never understood clearly before, thanks for that. That video also ignores feedback, distortion, current requirements. easy to be misinterpreted.
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Level Controls

Electro-voice AT37 Attenuator's spec says 16 ohm; AT38 spec says 8 ohm.

https://products.electrovoice.com/binary/AT37%20and%20AT38%20EDS.pdf

EV instructions say start at 0 and cut from there. Zero as start, and positive numbers indicating more or even more attenuation (not boost)

My level controls were evidently custom via Fisher: innards: exposed copper wound ceramic; exterior bronze finish recessed cup/handle for flush mount. A centered position, then boost or cut from that.

The level controls are after the electro-voice 16 ohm crossover X336. Electro-voice crossovers were contained in a can filled with tar (smaller x36 shown), mine are 62 years old.

https://products.electrovoice.com/binary/X6_X8_X425_X825_X36_X336_X2635_Engineering_Data_Sheet.pdf

this shows X336 crossover and electro-voice attenuators AT37 used in various Electro-voice 3 way Speakers.

https://www.ebay.com/itm/VINTAGE-EV-CROSSOVER-X336-2-PONTETIOMETR-CENTURION-VERY-CLEAN/274619211421?...

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Components (anybody still awake?)

All my speaker's components came from my uncle's Fisher 'President II Console I inherited, using electro-voice drivers and crossover. I have all the components, burned the wood in my fireplace.

https://www.radiomuseum.org/r/fisher_president_ii_console_3000m.html

Electro-voice speakers used their 15WK; Fisher chose the 15W

https://www.ebay.com/i/114584280677?chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&am...

https://products.electrovoice.com/binary/15W,%2015BW,%2015WK,%2015BWK%20EDS.pdf

Monster magnet, they weigh 37 lbs each. I've re-coned the woofers twice, I just checked, paper/cloth cone/coil kits still available. I have a spare 15W downstairs also.

I replaced the original T35 horn with T350 which is +3db efficiency, useful as we age, nice to have the level control.

http://www.cieri.net/Documenti/Istruzioni/Electrovoice%20-%20Tweeter%20T35,%20T35B,%20T350.pdf

spare pair downstairs.

the midrange is this crazy compound diffraction horn

https://products.electrovoice.com/binary/847A%20EDS.pdf

it looks like hell, but sounds terrific.

spare downstairs

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

These Level Controls give a lot of flexibility, BUT, it takes a lot of work getting both sides properly matched, the various sound positioning options of the McIntosh Mode Switch is the key my success. As frequencies change, i.e. you don't want certain piano notes left, others centered, others right. Imagine a singer's voice wandering. it's a big sigh of relief when you finally get it.


three_easy_payments's avatar
three_easy_payments
2,097 posts
 
@elliotb  

That video also ignores feedback, distortion, current requirements. easy to be misinterpreted.

That was the whole point of the video was to be misinterpreted in order to bias the viewer into preferring a 4 ohm speaker design - always, because it will be louder (all things equal, which of course they are not). Eric does make the completely worthless disclaimer at the beginning of the video that his viewpoint is only through the perspective of a speaker builder and doesn't consider the amplifier whatsoever.  Why is this worthless?  Because there is always an amplifier and speakers respond to amplifiers differently depending on the amp design.

Can you even imagine a video where an Andrew Jones or Nelson Pass plays photon torpedo noises through 4 ohm and 8 ohm speakers while claiming the one producing the loudest noise is the best - always - categorically....and even to go as far as claim the 8 ohm is obsolete?  It's laughable and goes to show the market Eric is largely targeting. This doesn't mean his speakers don't sound decent - it just means his marketing methods can be off-putting because he assumes people are stupid - at least in a video like this.   
luisma31
516 posts
 
+1 @atmasphere and
@lewm
Impedance matters on the load presented to the Amp, as Lew said there is no free lunch, the autorformers yes work if you have the problem but it is best to avoid it.As @charles1dad explained and he is very fond of low power SETs you can benefit ALOT from the 16 ohm Impedance.

Chuck's post as much as I respect and sympathize with his opinions it could be misleading, it depends on which specific experience he might have, IIRC he has Pass amps?
My own experience with several tube amps (especially SET) you would want if possible 16 ohms. Atmasphere amps are a special case have MA-1s myself and they can work with 8 / 6 ohms but 12 and 16 ohm are definitely better

Just my 2c
luisma31
516 posts
 
For the OP, if you have some small stand mounts Elacs B6 or such, attach these in parallel with your mains and let us know what happens to resolution of the mains, I have done it with both tubes and SS and in both cases lowers resolution and increases distortion
luisma31
516 posts
 
I didn't remember you had Sound labs Lew, wow, that is something I would love to listen to, my speakers made by Duke are very good but he is / was a Sound labs dealer dealer some eons ago and he still praises the sound
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