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

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.

If it has a digital display its a DVM and should have a similarly high impedance like a VTVM does. A multimeter is an older analog device with an analog meter. Its impedance is much lower and so its voltage measurements in sensitive circuits will be lower than actual (Ohm's Law after all...). I agree that 'multimeter' and 'DVM' are often conflated.

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.

Ralph - the Wagner you cite, what is your reference LP for that ?
best to you in the new year ?

London/Decca Solti conducting the London Philharmonic. My copy is a London 'Blue Back'.

@mijostyn +1
The room that I heard that system in most recently was built to accommodate the stereo and specifically the Sound Labs. It really was a nice setup, and could play some impressive dynamic range. He was running 2 pair of our MA-2s and until Dr West started messing with the spacing on the B1 subs, you couldn't clip the amps. It would be interesting to hear what those speakers could do with modern room correction and crossovers. The B1 sub had a very nice impedance curve if you had tube amps; it was as high as 32 ohms and I don't think it got below 16 ohms anywhere in its range.

The diaphragms have a very limited Xmax. They get non linear easily creating distortion at higher frequencies never mind the doppler effect. The ESLs become even more effortless and higher sound pressure levels stay perfectly controlled and relaxed. Without subwoofers the ESLs will start sounding stressed at higher volumes. This is certainly the case with Acoustats. I can not see why it would be different with Sound Labs speakers.

Roger used to make the B1 subwoofer which was an ESL panel that, if you had a pair of them, sat between the A1s creating a wall of ESL from one side of the room to the other. Several of my customers have had this sort of setup, using an electronic crossover so there was no bass excursion on the mains. I seem to recall the crossover to be about 200Hz. By getting the bass off of the mains they got more transparent.


IMO there were tradeoffs- the problem being that the Sound Labs and MA-2s driving them were a pretty transparent system for which the crossover at the time was no match. Roger began to mess with the spacing on the sub, and the later versions seemed to get harder to drive on account of the spacing between the diaphragm and stator being increased (inverse square law...).


I like to play my system at some pretty high levels too. If you want the entrance of the gods into Valhalla to sound right, you can't pussyfoot around with the volume; Wagner scored a serious brass section at that point and its not the sort of thing you sleep to :)

Of course you understand that I spend far more time playing our own amps than I do most solid state amps, and by comparison my comments are correct. I concede there is a perspective issue afoot!

Btw, I respect your opinion and I don’t try to make any offense to any one but only post facts and that’s all.

Just before that:

That manufacturer is totally wrong and as usual he never gives/gaves a first hand measured facts that can prove his false information. Exacvtly like today always takes/took another reference that proves nothing here, so useless to give him an answer.

You know, in the world exist honest and dishonest people. Make your own judgement because this " episode " is repeated again for the 1,000 time.

The contradiction here is pretty obvious, as are the motives behind it.

I take it then, @rauliruegas that when given the choice of educating yourself, or being stupid, you didn't choose the former.


Instead, you chose to make me wrong for the sake of making yourself seem to look better. In time you might sort out that this technique does not work. But at any time, you will find that redemption is readily available- just read the article I linked, and google the topics I mentioned, and really study them. This is engineering school stuff- if you are fluent with it, you won't appear to be stupid *or* ignorant!

When you say:

"" and it’s brigth, agressive, high dynamic power, with ryhtm, extraordinary at both frequency extremes, sometimes harsh ( listen to a trumpet/horn player at real SPL seated at 3 meters . ). ""

That’s how at real SPL sounds/performs a good SS electronics designs. Music have all those adjectives and many more: natural brigthness or natural agressivenes or even sometimes harsh sound is how the JC-1's will performs when the recording asked for. It's not because it needs higher feedback levels.

Issue is understaND HOW LIVE music SOUNDS AND WHAT RECORDING MICRO’S PICK-UP AT REAL spl: THAT’S ss THAT’S THE ONLY WAY TO STAY NEARER TO THE RECORDING TRUER TO THE RECORDINGS. tUBES CAN’T DO IT FOR SEVERAL WELL DOCUMENTED REASONS/FACTS. 

You must certainly be aware that tubes have no problems at all reproducing the aggressive nature of a trumpet at close range (and played loudly, as that can make a big difference). In fact everything you mentioned in the above quote (which very much reads as if you are saying that only solid state amps can do) tube amps do easily. You really need to try harder than that.

What you missed in my comments was that I was not advocating tubes, in the same way that I was not advocating typical solid state amps that lack sufficient feedback. They **both** have failings, so you pick your poison: either a bit of euphonic warmth or a harshness and brightness.


OR:
If the amp has **enough** feedback, it will simply be neutral. To do that takes a lot of feedback, and as I mentioned, putting that much feedback on most tube or solid state amps will cause them to oscillate due to the phase margins being exceeded. Now I tried to get you to google that, so you'd know what I was talking about. This is the difference between education and ... well... not.


Now given that any amp will have distortion, the trick is to minimize it, and the way to do that with any amplifier is to simply allow it to drive a load that is higher impedance (and usually less weird phase angles as a result). IOW, simple advice: If you want the most out of your amplifier investment dollar, don't make your amp work hard for a living.


When the amp has an easy job, it makes less distortion. Less distortion means less coloration (warmth or brightness).

" all due to distortion .." what are you talking about, where are your facts?

Your inability to understand the facts isn’t my fault. I’m writing this so you understand that I presented the facts *already*.


If you actually have a genuine interest in learning more of what I posted previously (instead of simply acting on a desire to make me wrong), google ’Gain Bandwidth Product’ and ’phase margin’ and read up. Then you will see why what I posted is correct. FWIW these are engineering topics and may be a little dry. For more information you might also read this article by Bruno Putzeys on feedback. In this one you don’t have to work out the math, if you allow yourself to trust that he did his math homework (in case you don’t know who he is, Bruno is one of the top designers of class D product in the world, responsible for the Purify and Hypex modules):
https://linearaudio.net/sites/linearaudio.net/files/volume1bp.pdf

After reading this article, you should understand why the Parasound is running insufficient feedback, and so has a brightness.

Ignorance is curable- stupid is forever. I’m pretty sure you’re not the latter, so now you have an opportunity.

Ralph, What I recommended to Elliot is that he first experiment with the settings of the L-pads in his speakers until he arrives at a solution that he wants to live with long term. Doing this would automatically involve accounting for the driving ampifier and the length of speaker cable. Once that steady state is arrived at, do you see anything wrong with swapping the L-pads for high quality high wattage discrete resistors that represent the resistance across each L-pad after their final adjustment? Anyway, that is what I would do. My approach is based only on listening to my Sound Labs speakers (first the M1s, then the 845PXs) with vs without the Brilliance control in circuit. Big improvement in transparency and air without that L-pad.

I don't doubt it. But as I said, if you make changes in the amp or speaker cables you might find that you want to change the setting as well. Once you know what it is, of course a fixed resistor of good quality will be better.

JC-1’s are great monoblock amplifiers and is unfortunated that today are out of production because can compets or could be a true challenge to even names as FM Acoustics, Boulder, Gryphon, CH, Dartzeel and the like.

The JC-1 was a good solid state amp for its time, but like many other amps from that time didn't have enough feedback to really sound neutral- and that is why it can be a bit bright and harsh- all due to distortion. Combine that with an ESL and its going to be very bright... fortunately the Sound Lab has adjustments to allow you to adjust the speaker to the voltage response of the amplifier, so you can tone it down a bit.


The reason the distortion is there is due to insufficient feedback. This prevents the distortion caused when feedback is applied to be suppressed. Put another way, feedback suppresses distortion, but then makes some of its own. To allow the amp to get rid of that, you need more feedback, and most of the solid state amps of this era (and before) lacked the Gain Bandwidth Product and phase margins that were needed to run the required feedback. So they simply didn't.


So ya picks yer poison; harshness and brightness, or a little extra warmth but the highs are detailed and relaxed. This is why tubes are still around BTW; solid state is supposed to be 'neutral' but its hard to call it that when its bright and harsh.

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.

Problem is that speaker manufacturers never gives the whole impedance facts/measurements/charts. Tha’s why generalizations to say 8 ohm speaker spec means almost nothing. I choosed at random ( between hundred of ST measurement. ) and you can read there that your words are not exactly rigth with some of those speakers, same for maplifiers.

Whenever anyone asks if a speaker will work with our amps I take a look at the impedance curve if one is available. But if the speaker is rated 8 ohms or more I pay attention, and if the speaker is rated higher, like 16 ohms, I’ve yet to run into one that didn’t work. I’ve seen some speakers, like B&Ws, that are rated ’nominally 8 ohms’ but feature dual woofers, which are wired in parallel, although the midrange and tweeter array is certainly what I would call ’8 ohms’. The woofer array, even though it may have peaks at 8 ohms or higher, is something I would regard as more of a 4 ohm load. So you do have to be careful about this issue; but in the case of higher impedances it usually no worried at all.


The Sound Lab is not a speaker rated at 16 ohms or 30 ohms despite both impedances being present at some frequency. While it is difficult for most solid state amps to make power on this speaker owing to the 30 ohm impedance in the bass (which is why a tube amp of 150 watts can easily keep up with a solid state amp of 600 watts on this speaker), all this means is that you might see about 1/4 the power the amp is rated for into 8 ohms. However, and this is important, as the frequency goes up above about 5-7KHz, the impedance is dropping, to a low of about 1.5-3 ohms (depending on the setting of the Brilliance control) at 20KHz. Like almost any full range ESL, the impedance varies by about 10 or 9:1 from the bass to the highs. The issue here is that a good quality solid state amp will double power as impedance is halved. With a box speaker, this is fine because a peak in the impedance curve usually represents a resonance so this property is welcomed. But this isn’t the case with the Sound Lab. It needs about the same power in the bass region as it does in the high treble region to make the same sound pressure at that frequency. This means that an amp that can double power (and the Sound Lab does not challenge most solid state amps in that regard) will be excessively bright due to this property.

To get around that issue, the Sound Lab is equipped with a number of settings to modify the speaker’s response. The Brilliance control is there to deal with excessive brightness, the bass settings allow you to boost or cut the bass, depending on if you have a solid state amp (boost) or tube amp (cut). IIRC there are midrange settings too.


One nice thing about this speaker if using solid state is that the bass impedance (where the power is) is high, resulting in low distortion for nearly any amplifier. Low distortion means less harmonics from the bass notes, so an amusical harmonic like the 7th, 9th, 11th or 13th to which the ear is keenly sensitive, will be greatly attenuated. IME this is beneficial to all amps.


The mod that @lewm did seems a wonderful upgrade for the speaker!

Now, getting back to the amplifier factor, it is quite likely that the old version of the 845PX could have been driven more satisfactorily at midrange frequencies using a typical SS amplifier, because of the lower output impedance exhibited by most SS designs, but then I wouldn't have the OTL-ness to which I am addicted. I was told that SL use SS amplifiers at their factory, which is probably why the problem went unnoticed for a while.

@lewm  I have customers with solid state amps and they report the same thing that our customers with tube amps do- that when the error in the backplate was corrected, the speakers instantly were easier to drive and sounding better at the same time.

Sound Lab was using a Boulder amplifier, which is why they may not have noticed a problem. But remember that resistor that got pulled out? It was a composite of eight resistors, totaling 200 watts! Obviously a lot of amplifier power was being used to heat those parts up. So its no wonder when that problem was corrected that the speaker got instantly better.

I can't understand why you and any one else speak of 16 ohm, 8 ohm or 4 ohm speakers when the speaker impedance is not flat , it changes over its frequency range.

Simply put, a nominally 16 ohm rated speaker will be higher impedance than a nominally rated 4 ohm speaker.


It is true that no speaker has flat impedance, but the impedance variation is not so important as the overall. If the impedance is overall higher, the amp will be lower distortion. I suspect that this is one of the reasons the Sound Lab is so transparent, as in the bass region its 30 ohms. Any bass energy made by any amplifier will have less harmonic distortion simply because the amp will be lower distortion where the power is needed most. And for all that, the impedance of the speaker varies by about 9:1 from bass to 20KHz.

and used cable with plenty of conductor to do the job.

@atmasphere by plenty you mean AWG correct?

Yes. Bad editing.

@elliotnewcombjr  The level controls are there to allow you to adjust the speaker to your amplifier's voltage response. But to maintain the crossover point they should be the same value as the original.

@mijostyn If you're getting a new Sound Lab, Roger corrected for the issue to whicht @lewm was referring. So you shouldn't need to do any mods.

I am not sure that generalization (16 ohms = lower amplifier distortion) would apply to every variety of solid state amplifier.

@lewm If you know of one that actually has lower distortion into 4 ohms as opposed to higher impedances I'd love to know about it. I've yet to find one, starting from primitive driver transformer designs of the 1960s to self oscillating class D amps of the 2020s. If there is one out there it is a very rare exception!

My amp has 4, 8, and 16 taps. If my speakers are 4, what strain, if any, on any of my amp tubes will that have?

If you put the speaker on the 4 ohm tap, none, but the output transformer will likely be losing some performance- they can often lose as much as an octave of bandwidth in the bass, and they will run warmer. That warmth is also causing the amp to make slightly less power, as the heat is coming from the power tube output.

And yet, the guy who designs some of the most fantastically successful speakers made anywhere in the world today says nevermind 16 ohms, even 8 ohms is obsolete.

As far as solid state is concerned, this may well be true from a marketing perspective. But this is high end audio, where minimizing colorations is important, and distortion causes most of the colorations we hear- for example the brightness/harshness of solid state. The 3dB more power thing is a really weak argument- put another way, if you want to get the **best sound quality**, your amplifier investment dollar is best served by a higher impedance speaker. OTOH, if **sound pressure** is your goal, then you have a 3dB argument for 4 ohms (as opposed to 8) **if** you have a solid state amp that doubles power into 4 ohms. But you really pay a price doing 4 ohms- not only do you have more distortion, but most amps will run warmer (even class D) and the speaker cable becomes critical. On that basis it would be a stretch to claim state of the art performance when the amplifier is thus compromised.

His demo is about loudness, saying 4 ohm will produce 3db more VOLUME than 8 ohm. IOW, it helps him with efficiency.

To be completely correct, it helps with **sensitivity** which is not the same as efficiency. Efficiency is unaffected. What the higher sensitivity number is saying is that the amp is now being asked to make twice as much power! That's completely different from a speaker that is 3dB more efficient- the latter would mean that an amp with half the power would play just as loud!


Like everything electronic, math is involved. Efficiency is stated as a certain sound pressure with 1 watt. Sensitivity is stated as a certain sound pressure with 2.83 volts.  Into an 8 ohm load 2.83 volts is 1 watt; into 4 ohms its 2 watts. This is a 3dB difference. Since tube amps don't double power as impedance is halved, efficiency is the more useful specification, but since the industry went solid state, the sensitivity spec has taken over. You can make any speaker seem more "efficient" by reducing its impedance though parallel drivers but what is happening is the sensitivity is being increased while the efficiency is unaffected. You do have to pay attention to this nuance when selecting a speaker to work with an amplifier!

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

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

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?

Bias can be pretty important. Usually it is used to place the output device (tube or transistor) in the most linear portion of its operating curve. So it can have a noticeable and measurable effect on the sound.


The inductance of the speaker cable plays a role, but so does capacitance and DC resistance. I would not place too much importance on any one characteristic. In theory, the cable has what is called 'Characteristic Impedance' which is the character where the cable is properly terminated by the impedance specified. Put another way, if the cable has a characteristic impedance of 8 ohms, if an 8 ohm load terminated the cable, there will be no reflections from the load back to the source. In this case from the speaker back to the amplifier. But in practice, no speaker is a perfect resistive load, and the back emf from the speaker dominates the minor reflections, so what becomes more important is that the speaker cable simply be kept as short as possible so that its errors are minimized. This FWIW is why I developed a balanced line preamp, so the amps could be placed as close to the speaker as practical. When doing this you hear an immediate improvement in bass impact and resolution. In a nutshell- keep your speaker cables short and used cable with plenty of conductor to do the job.


The amount of power you have might affect how much bandwidth the amplifier has. This is particularly true of SET amplifiers, where power past about 7-8 watts falls short of the definition of 'hifi' (the smaller the SET, generally the wider bandwidth it is; this is why the type 45 power tube, which is only good for 0.75 watt, is the 'best' sounding). With push-pull tube amps this limit is more like 60-120 watts, but in both of these examples its assumed that there is an output transformer on the tube amp (some tube amps don't have output transformers so are not bandwidth limited at any power level). Some solid state designs don't scale well as power is increased, but most of those I've encountered are older designs employing coupling capacitors at the output of the amp. 

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