90% of Reproduced Sound Quality Comes From . . .

[MylesBAstor]

I know forum members are tired of me discussing my system, But lets face it, they are an improbable match on paper. Sterophoile reviewed the 402au and found them to have an output impedance of .22 ohms and and a rise in distortion as the speaker impedance dips below 4ohms. http://www.stereophile.com/solidpoweramps/moscode_402au_power_amplifier/index4.html.
Lets put that toghether with ML CLS. View attachment 276 http://www.stereophile.com/floorloudspeakers/650/index11.html Assigning the CLS an impedance of 4 ohms is being generous. 33 ohms at 1khz, 2.5 ohms at 10khz and 1.9 ohms at 20khz. Sterophile suggests avoiding speakers that dip below 4 ohms.
My listening experience makes them an almost ideal match. I even get excellent bass. Many have called the CLS edgy and and bass shy. One can assume I have no interest in a speaker that sounds that way. Manny ahve suggested that a solid state behemoth is the only way to go. They generally have very low output impedance and the ability to remain stable with complex loads. Such combos have left me cold or tend to be prohibitively expensive. So the question what's going. We can design a near perfect amp based on the parameters we know how to measure. But those devices have usually been found wanting musically. It is why stereo design is part science part art.
Finally I would suggest i would not even consider an SET with he big Wilsons. They must be a good match or why would Steve Bother. I'll be hearing them later this month and evaluate what's going on.

Speaking of solid-state amps, did you ever have a chance to try the Electrocompaniet on the CLSs?

Never heard the combo but someone I knew who had the original Apogees (that dipped to a 1/4 ohm) used that amp years ago and it sounded darn good. (Plus it could handle the load.)

 

[Gregadd]

I never did try it. Back then my dealer paired the Rowland Research Five with excellent results. The now defunct Mirror Image amps were great also. The trouble with ss amps at that time was that they had all been designed to work with translucent dynamic speakers. The CLS would sizzle like bacon in a frying pan with most of them. Given that George was designer (in whole or in part) of the Electrocompanient and based the Moscode on that design it is likely they were an excellent match.

The Lamm would seem to have some serious problems with high output impedance that would support the claim of problems at the frequency extremes. IMO I credit the high cost of SET/DHT amps as the cost of dealing with that problem. Less troublesome to me is the low wattage. The Wilsons are very efficient. The current and voltage output is excellent. In my opinion that is way more important than watts.
Like I said the proof is n the pudding not the recipe.

 

[MylesBAstor]

I never did try it. Back then my dealer paired the Rowland Research Five with excellent results. The now defunct Mirror Image amps were great also. The trouble with ss amps at that time was that they had all been designed to work with translucent dynamic speakers. The CLS would sizzle like bacon in a frying pan with most of them. Given that George was designer (in whole or in part) of the Electrocompanient and based the Moscode on that design it is likely they were an excellent match.

The Lamm would seem to have some serious problems with high output impedance that would support the claim of problems at the frequency extremes. IMO I credit the high cost of SET/DHT amps as the cost of dealing with that problem. Less troublesome to me is the low wattage. The Wilsons are very efficient. The current and voltage output is excellent. In my opinion that is way more important than watts.
Like I said the proof is n the pudding not the recipe.

Greg-

Guess it was about ten years ago that listened to the Rowland 12s with my Prodigys. Very nice combination and a great altenative to my then cj Prem 12s. Review, unfortunately never made it to print

 

[marty]

Tom, I can appreciate the conditions you think are necessary to minimize the effect of the listening room acoustics. But are they doable, particularly the requirement for near-field listening (i.e. 6 ft from the speaker)? I think some manufacturers would clearly say their speakers are not designed to have good driver integration unless the distance to the listener is much further back. I'm thinking of Dunlavys and Wilsons in particular. I don't have any Wilson manuals in front of me but I don't recall his module azimuth adjustments have a scale that puts the listener 6 feet from the speaker; 9 or 10 ft seem more likely as I recall. So if the 6 ft requirement is to be adhered to, does this rule out some well-regarded speakers for playback consideration?

 

[Steve Williams]

Tom, I can appreciate the conditions you think are necessary to minimize the effect of the listening room acoustics. But are they doable, particularly the requirement for near-field listening (i.e. 6 ft from the speaker)? I think some manufacturers would clearly say their speakers are not designed to have good driver integration unless the distance to the listener is much further back. I'm thinking of Dunlavys and Wilsons in particular. I don't have any Wilson manuals in front of me but I don't recall his module azimuth adjustments have a scale that puts the listener 6 feet from the speaker; 9 or 10 ft seem more likely as I recall. So if the 6 ft requirement is to be adhered to, does this rule out some well-regarded speakers for playback consideration?

Marty I completely agree. If I were to listen to my speakers at 6 feet I would have tinnitus in less than a day. Wilson measurements are (distance tweeter to tweeter) X 1- 1.4 = listening postion with specific advice re toe in. I do agree that each speaker be aimed and focused at the ipsilateral ear. IMO this is where Wilson excels by being able to adjust height and position of each of the upper modules

 

[Gregadd]

So when we talk about the Lamm and it only having 32 watts its abilty to drive the big Wilson X2 may be more dependent on these specs.
Power

HIGH IMPEDANCE SETTING

continuous 1 KHz sine-wave power,
with no more than:

1% THD (FTC) @ rated line voltage
1% THD (FTC) @ rated line voltage
1% THD (FTC) @ rated line voltage
1% THD (FTC) @ rated line voltage







150 Watts into 8 Ohms.
300 Watts into 4 Ohms.
500 Watts into 2 Ohms.
700 Watts into 1 Ohm.

LOW IMPEDANCE SETTING

continuous 1 KHz sine-wave power,
with no more than:

1% THD (FTC) @ rated line voltage
1% THD (FTC) @ rated line voltage
1% THD (FTC) @ rated line voltage




150 Watts into 4 Ohms.
300 Watts into 2 Ohms.
450 Watts into 1 Ohm.

Maximum (clipping) Output Voltage


HIGH IMPEDANCE SETTING

with continuous 1 KHz sine wave,
@ rated line voltage:







49 Volts peak into 8 Ohms, corresponding to 300 Watts peak.

49 Volts peak into 4 Ohms, corresponding to 600 Watts peak.

44.72 Volts peak into 2 Ohms, corresponding to 1,000 Watts peak.

37.42 Volts peak into 1 Ohm, corresponding to 1,400 Watts peak.


LOW IMPEDANCE SETTING

with continuous 1 KHz sine wave,
@ rated line voltage:





34.64 Volts peak into 4 Ohms, corresponding to 300 Watts peak.

34.64 Volts peak into 2 Ohms, corresponding to 600 Watts peak.

30 Volts peak into 1 Ohm, corresponding to 900 Watts peak.

Maximum (clipping) Output Current


HIGH IMPEDANCE SETTING

with continuous 1 KHz sine wave,
@ rated line voltage:




6.12 Amps peak into 8 Ohms, corresponding to 300 Watts peak.

12.24 Amps peak into 4 Ohms, corresponding to 600 Watts peak.

22.36 Amps peak into 2 Ohms, corresponding to 1,000 Watts peak.

37.42 Amps peak into 1 Ohm, corresponding to 1,400 Watts peak.


LOW IMPEDANCE SETTING

with continuous 1 KHz sine wave,
@ rated line voltage:



8.66 Amps peak into 4 Ohms, corresponding to 300 Watts peak.

17.32 Amps peak into 2 Ohms, corresponding to 600 Watts peak.

30 Amps peak into 1 Ohm, corresponding to 900 Watts peak.


Manyinclluding me have argued that volatge and current are more important than watts. This often explains why a low watt tube amp can sound more powerful than 'higher watt ss brother.

 

[Steve Williams]

what you folks don't understand about this amp/speaker combination (X-2/ML3) is that with speaker efficiency of 95 Db, I can play at near ear bleeding SPL levels without the amp clipping.

32 watts are more than sufficient. In fact prior to the ML3 I owned the ML 2.1 which at 18 wpc was also more than sufficient to drive my speakers

 

[FrantzM]

Gregadd

The Wilson are "big" , no doubt. They are also 95 dB efficient and a fairly stable impedance. So Yes a 32 Watts /ch amp can drive them to reasonable high SPL. If you want SPL capable of splitting walls or if you want clean, sustained 106 dB peaks at the seating position, they are not the amp.
Efficient speakers help in that regard and keep in mind that how we hear is logarithmic... a 200 Watts amps is only 3 dB louder than a 100 amp and to get 3 dB more requires a 400 watts amp...

SS can swing out prodigious amount of Voltage and Current.. I remember back in the days, there was a story about Mark Levinson (the man) using one of his amp, the ML-2, to literally weld, like in Arc Welding .. unlikely with any tube amp and yes, the ML-2 would drive the X-2 as well ... It was a 25 Watts/ch amp.
Now the specs you have are wrong, they are likely for the LAMM hybrid (SS output, Tubes input), NOT the SET OB has, no way the SET would do that kind of current , simply not possible ...

Frantz

P.S. I also would quickly venture that the LAMM would likely drive the big Von Schweikert as well. The efficiency figures and in the case of the VR-11 the impedance lowest modulus is only 5 Ohm and an average of 8 ohms, are very similar, in fact the LAMM would have been relieved from the low bass. The VR (both the 9 and 11) rely on internal SS amplifiers for their low bass..

 

[Steve Williams]

Here are the specs on the ML to which Tom alluded


http://www.lammindustries.com/PRODUCTS/ML3spec.html

 

[FrantzM]

OB

I also must point to you that the distance Wilson recommend is for the drivers to appear as one source, closer than that you hear a particular driver more than the others, resulting in a very skewed FR. The same applies for most multi driver speakers.. Some speakers, like the Quad ESL can be listened to very close with no problem..

Frantz

 

[Gregadd]

Gregadd

The Wilson are "big" , no doubt. They are also 95 dB efficient and a fairly stable impedance. So Yes a 32 Watts /ch amp can drive them to reasonable high SPL. If you want SPL capable of splitting walls or if you want clean, sustained 106 dB peaks at the seating position, they are not the amp.
Efficient speakers help in that regard and keep in mind that how we hear is logarithmic... a 200 Watts amps is only 3 dB louder than a 100 amp and to get 3 dB more requires a 400 watts amp...

SS can swing out prodigious amount of Voltage and Current.. I remember back in the days, there was a story about Mark Levinson (the man) using one of his amp, the ML-2, to literally weld, like in Arc Welding .. unlikely with any tube amp and yes, the ML-2 would drive the X-2 as well ... It was a 25 Watts/ch amp.
Now the specs you have are wrong, they are likely for the LAMM hybrid (SS output, Tubes input), NOT the SET OB has, no way the SET would do that kind of current , simply not possible ...

Frantz

P.S. I also would quickly venture that the LAMM would likely drive the big Von Schweikert as well. The efficiency figures and in the case of the VR-11 the impedance lowest modulus is only 5 Ohm and an average of 8 ohms, are very similar, in fact the LAMM would have been relieved from the low bass. The VR (both the 9 and 11) rely on internal SS amplifiers for their low bass..

My apology. You are right. Those are not the ML3 specs. I just cleaned my glasses. I still maintain that the current and voltage ratings are impressive. Wattage is still one of the most misunderstood specs. If most amps ran for any significant period at thier maximum rated output they would probably blow up. Generally you are talking about dynamic headroom. I have no doubt ss can produce prodigious amounts of current and voltage. My point is that my CJ Premier 11a put many much higher power ss amps to shame. Many had 2 to 3 times higher wattage output ratings.

 

[FrantzM]

My apology. You are right. Those are not the ML3 specs. I just cleaned my glasses. I still maintain that the current and voltage ratings are impressive. Wattage is still one of the most misunderstood specs. If most amps ran for any significant period at thier maximum rated output they would probably blow up. Generally you are talking about dynamic headroom. I have no doubt ss can produce prodigious amounts of current and voltage. My point is that my CJ Premier 11a put many much higher power ss amps to shame. Many had 2 to 3 times higher wattage output ratings.

Greg

I would not like the thread to devolve into a SS vs Tubes debate. The ML 1.2 specs are very good. No doubt but these numbers are because of its Output stage which is SS. Now if you were to look at specs from the best SS would see even more spectacular numbers (The Krell Master Reference Amplifer could swing voltage and amps that makes no sense .. in term of pure power it is capable of 16,000 watts (!!!!!!!!) at 0.5 ohms ...I am by no means implying that they are better than the ML 1.2... Now about the fact that often Tubes sound often more "powerful" than some SS it is in gross part due to the clipping characteristics of tubes amplification.. This is not the place to get into the details of Electronics circuits but suffice to say that Tubes clip more gracefully than the usual SS.. The THD they produce is often richer in even Harmonics than SS under the same conditions .. so some tubes can be driven harder without sounding bad ...
back to the subject at hand ..

Frantz

 

[Steve Williams]

The THD they produce is often richer in even Harmonics than SS under the same conditions .. so some tubes can be driven harder without sounding bad ...

I agree.

Hence the 3% THD on the ML3 is very tolerable

 

[rsbeck]

what you folks don't understand about this amp/speaker combination (X-2/ML3) is that with speaker efficiency of 95 Db, I can play at near ear bleeding SPL levels without the amp clipping.

32 watts are more than sufficient. In fact prior to the ML3 I owned the ML 2.1 which at 18 wpc was also more than sufficient to drive my speakers

I can corroborate this. I've been in Steve's listening room/theater and have heard his system easily play to reference levels with both the 18 watt ML 2.1 and the 32 watt ML3.

Here's the really strange part -- please don't kill me, Steve -- I actually preferred the sound of the system with the 18 watt ML 2.1's in place.

 

[Gregadd]

I suppose someone has to have the last word. I started down this raod to try and explain Steve's choice of an SET/DHT to drive The X-2. An unlikely choice IMO. One of the the prospects of getting old is I have no desire to rehash everything I 've learned in 30+ years in audio. I am willing to listen to anyone with a good argument. I have satisfied myself both in theory and practice that voltage and current play a huge factor in the ability of an amp to drive a loudspeaker. As much as wattage. Clipping, even and odd order distortion are different topics. and It's not the only factor. If soemone wants enlighten me to the contrary they can give me a link via private message.
I saw the arc welding article on the cover of a magazine. Can't remember which one. I also know of some monster tube amps from Jadis, VTL, and Atma-Sphere. None of these amps or the Krell Reference Standard is the same class as the CJ Premier 11a or its solid state competitors.
Lastly, I did start a thread on amp speaker interface. This subject has been kicked around endlessly on Audiogon.

 

[rsbeck]

The THD they produce is often richer in even Harmonics than SS under the same conditions .. so some tubes can be driven harder without sounding bad ...

All theory of course, but this would explain Steve's system and maybe why I prefer the lower powered ML 2.1's in the chain.

I'm not trying to start any trouble, but I have to say this so my position makes sense.

I've always admired the Wilson sound, but I've never loved it. I hope that makes sense. I've admired the precision, the clarity, the focus, the detail, the air around the instruments, etc. etc. But, to my ears, it comes across a little clinical -- a little too much of a good thing.

I think it may just be that the tube distortion from the SET amps combines with all of that detail and focus, makes it musical and creates a sound-stage that feels ands sounds right to me.

Steve has some kind of synergy going between his speakers, room and other gear that is just incredible and the palpability must be experienced to be believed.

It'll make you question everything you thought you knew.

I walked out of there the first time thinking I was a bow-legged girl scout from Des Moines.

Took me three days to snap out of it.

Don't say you haven't been warned.

 

[tmallin]

I never did try it. Back then my dealer paired the Rowland Research Five with excellent results. The now defunct Mirror Image amps were great also. The trouble with ss amps at that time was that they had all been designed to work with translucent dynamic speakers. The CLS would sizzle like bacon in a frying pan with most of them. Given that George was designer (in whole or in part) of the Electrocompanient and based the Moscode on that design it is likely they were an excellent match.

The Lamm would seem to have some serious problems with high output impedance that would support the claim of problems at the frequency extremes. IMO I credit the high cost of SET/DHT amps as the cost of dealing with that problem. Less troublesome to me is the low wattage. The Wilsons are very efficient. The current and voltage output is excellent. In my opinion that is way more important than watts.
Like I said the proof is n the pudding not the recipe.

Current times voltage equals watts. The Lamm ML-3 Signature is both a low current and low voltage amp. See the specs here. Frankly, quoting this level of distortion and "peak" anything these days is just embarrassing for any audio product, not to mention one costing this much.

 

[tmallin]

Tom, I can appreciate the conditions you think are necessary to minimize the effect of the listening room acoustics. But are they doable, particularly the requirement for near-field listening (i.e. 6 ft from the speaker)? I think some manufacturers would clearly say their speakers are not designed to have good driver integration unless the distance to the listener is much further back. I'm thinking of Dunlavys and Wilsons in particular. I don't have any Wilson manuals in front of me but I don't recall his module azimuth adjustments have a scale that puts the listener 6 feet from the speaker; 9 or 10 ft seem more likely as I recall. So if the 6 ft requirement is to be adhered to, does this rule out some well-regarded speakers for playback consideration?

Yes, near-field listening rules out a lot of huge speakers with a lot of drivers strung along a large area of a baffle. More and bigger is not necessarily better. Getting your listening room out of the equation is best accomplished when your listening room acoustics are overwhelmed by the sheer difference in volume between the direct sound from your speakers and the reflected sound from your room. With a given speaker, one easy way to increase the ratio of direct-to-reflected sound is to simply angle the speakers directly toward your ears and listen physically very close to the speakers.

I would tell you that for near-field listening you should be listening to either a true line source, or a true coaxial speaker. But I won't since I don't think those are so great for close-up listening, either.

Yes, a line source will always center the stage directly in front of your ears due to the Haas effect. But there will be vertical image stretch because of the significant sound output above and below that line. This is not a true height illusion since all that happens is that sonic images get vertically stretched in a funhouse manner.

A coaxial array will act as a point source, but such point sources tend to sound like all the sound is coming from a narrow horizontal slit in front of your face--there is too little height illusion.

What sounds best up close is a coherent array of vertical drivers with tweeter on top, midrange in the middle and woofer on the bottom, all fairly close to each other. I cannot hear out the individual drivers on my Harbeth M40.1s even if I listen to them from two feet from the plane of the speakers--and note that the speakers are themselves almost 30 inches tall and that the distance between the center of the woofer and the center of the tweeter is about 18 inches. THAT is a coherent array AND it reproduces an EXCELLENT height illusion in stereo with choruses or organ pipes frequently "visible" above other instruments and with lots of apparent vertical action or projection from sopranos and treble instruments off the upper walls and ceiling of the recording venue. Maximal magic (midrange and otherwise) occurs when you listen close up with the Harbeths.

 

[MylesBAstor]

I suppose someone has to have the last word. I started down this raod to try and explain Steve's choice of an SET/DHT to drive The X-2. An unlikely choice IMO. One of the the prospects of getting old is I have no desire to rehash everything I 've learned in 30+ years in audio. I am willing to listen to anyone with a good argument. I have satisfied myself both in theory and practice that voltage and current play a huge factor in the ability of an amp to drive a loudspeaker. As much as wattage. Clipping, even and odd order distortion are different topics. and It's not the only factor. If soemone wants enlighten me to the contrary they can give me a link via private message.
I saw the arc welding article on the cover of a magazine. Can't remember which one. I also know of some monster tube amps from Jadis, VTL, and Atma-Sphere. None of these amps or the Krell Reference Standard is the same class as the CJ Premier 11a or its solid state competitors.
Lastly, I did start a thread on amp speaker interface. This subject has been kicked around endlessly on Audiogon.

I found this thread over at audiogon extremely interesting and has some bearing on this discussion-in part because it deal with issues like crossover and speaker design: Power output of tube amps compared to solid states; http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1267984978&openflup&143&4#143

In particular, I'm posting Ralph Karsten's response to a question about choosing an amplifier to drive the MBLs.

Ralphs Post:

In the last 20 years the use of SETs has really increased a lot. It has resulted in a lot of speakers that were simply not available 20 years ago. So these days its ten times easier to find a speaker that works with 'current source' amplifiers than it used to be.

Unsound, I can think of three speakers that if you put a tube amp on them, the result will be shrill, and all for the same reason: the amp will not double power as impedance is halved (or conversely, cut the power to 1/2 as the impedance doubles): the B&W 802, the Avalon Isis and the mbl101e. So if you are working with speakers that have similar impedance curves, I can totally see where you are coming from.

BTW the speakers on that short list are all examples of Voltage Paradigm technology, and its been my experience that when you mix Voltage and Power technologies, you will get a tonal aberration; 'shrill' is a common resulting aberration. Several others have been mentioned above, such as the 'wooly bass' that Duke was commenting too.

Ralph's post 2: Myles, the mbl has an impedance peak of about 8-9 ohms in the midrange driver. The designer is expecting the amp to reduce power by 3 db through this range. An amplifier with feedback will do it, one without will not. A good number of tube amps tend to sound shrill on this speaker even though otherwise they have plenty of power. So Michael was probably using an amp with a lot of feedback.

The problem here is that IMO, amps with feedback sound somewhat shrill out of the box, IOW its my opinion that a speaker that requires this will never sound like real music.

Kirkus, I know about the TIM articles but obviously amps designed to overcome that 'issue' were horrendous.

IMO the issue with feedback boils down to open loop propagation delay in the amplifier- IOW its a timing issue. The feedback signal simply does not arrive back at the input in time to make the correction. With a steady-state signal, the amp locks in pretty well over a few iterations, but with a constantly-changing waveform the amp will be chaotic. This is an interesting subject and I agree- a topic for another thread.

 

[tmallin]

Marty I completely agree. If I were to listen to my speakers at 6 feet I would have tinnitus in less than a day. Wilson measurements are (distance tweeter to tweeter) X 1- 1.4 = listening postion with specific advice re toe in. I do agree that each speaker be aimed and focused at the ipsilateral ear. IMO this is where Wilson excels by being able to adjust height and position of each of the upper modules

To prevent tinnitus, you just turn the volume down, Steve. Even in a small room, the volume from a non-line source halfway obeys the inverse square law. If you listen closer, you need less output from the speakers to reach a given volume at your ears. This is a benefit for all you folks who like those teeny-watt SET amps.

Not that I advocate near-field listening for Wilsons. The drivers are spread apart too far vertically. I doubt that no matter how you move the drivers back and forth you can get maximal inter-driver coherence at closer than eight feet or so back. Wilsons are not like my Harbeths.