Last week a friend of mine bought a X1 pre- and X250.5 poweramp. At the same time another friend of mine bought a pair of Levinson ML-6b preamps to accompany his Levinson ML-2's.
I myself operate a pair of ML-2's and a ML-3 on Acoustat fullrange Electrostatics.
Of course we were interested in some comparison with the three amps.
First the 2 x 200 Watts ML-3. It sounded very powerfull effortless reaching high soundpressure levels with no sign of stress at all, not very delicate or having much inner detail a brute force solution nice to have around for feeling Le Sacre du Printemps from Igor Stravinsky. Next the monophonic ML-2's with only 25 Watts Class A. Much more refined very precise crystal clear performance with pinpoint imaging but not a lot of depth and sometimes maybe to clean.
Then what would be in potency in our minds the refinement of the ML'2s with the power of the ML-3: The Passlabs X250.5 2 x 250 Watts.
The sound was very good vocals moved to the front there was depth and musicality at last. But to our astonishment the meter rapidely moved to the right corner when power was asked to deliver especially when a female singer like Kate Bush or Tory Amos were stating to sing loudly. The maximum listening level was not much louder then the pair of ML-2's and a way down compared to the Levinson ML-3.
I noticed this behaviour wit earlier Nelson Pass designs like the Stasis 300 optical bias and the S/1000 series II monoblocks I had. I liked the sound very much but they always seem powershy compared with Krell and Levinson designs of that era.
Especially compared to the Levinson ML-3 amp the X250 doesn't seem to deliver much power (maybe in the lower impedence regions I reckon?). The Acoustat has a lousy 82 dB/W 1 meter response with in the higher frequency region a impedence that is sloping downwards to maybe 1 Ohm. So I now the speaker can be critizised but it's there lik a lot of aothe old planars like the Apogees that are all treasured by there owners.
For the sound only I was considering to sell my ML-2's and ML-3 to buy a X350.5 but after the experiment I got reluctant because I do not think a couple of amps on paper (max 28 instead of the 20 of the X250) will not help a lot.
Can anybody tell my why this behaviour is typacal for Pass products or am I in error?
Thanks for the reactions.
ps Why are the X250 cooling fins designed as dustcollectors?
I myself operate a pair of ML-2's and a ML-3 on Acoustat fullrange Electrostatics.
Of course we were interested in some comparison with the three amps.
First the 2 x 200 Watts ML-3. It sounded very powerfull effortless reaching high soundpressure levels with no sign of stress at all, not very delicate or having much inner detail a brute force solution nice to have around for feeling Le Sacre du Printemps from Igor Stravinsky. Next the monophonic ML-2's with only 25 Watts Class A. Much more refined very precise crystal clear performance with pinpoint imaging but not a lot of depth and sometimes maybe to clean.
Then what would be in potency in our minds the refinement of the ML'2s with the power of the ML-3: The Passlabs X250.5 2 x 250 Watts.
The sound was very good vocals moved to the front there was depth and musicality at last. But to our astonishment the meter rapidely moved to the right corner when power was asked to deliver especially when a female singer like Kate Bush or Tory Amos were stating to sing loudly. The maximum listening level was not much louder then the pair of ML-2's and a way down compared to the Levinson ML-3.
I noticed this behaviour wit earlier Nelson Pass designs like the Stasis 300 optical bias and the S/1000 series II monoblocks I had. I liked the sound very much but they always seem powershy compared with Krell and Levinson designs of that era.
Especially compared to the Levinson ML-3 amp the X250 doesn't seem to deliver much power (maybe in the lower impedence regions I reckon?). The Acoustat has a lousy 82 dB/W 1 meter response with in the higher frequency region a impedence that is sloping downwards to maybe 1 Ohm. So I now the speaker can be critizised but it's there lik a lot of aothe old planars like the Apogees that are all treasured by there owners.
For the sound only I was considering to sell my ML-2's and ML-3 to buy a X350.5 but after the experiment I got reluctant because I do not think a couple of amps on paper (max 28 instead of the 20 of the X250) will not help a lot.
Can anybody tell my why this behaviour is typacal for Pass products or am I in error?
Thanks for the reactions.
ps Why are the X250 cooling fins designed as dustcollectors?
Don't worry be happy
Just read a Pass X350.5 review from a German Audio publication 'Stereoplay', 3/2005, http://www.stereoplay.de/suche/ergebnis.html?term=PassLabs) where its Labreport clearifies the matter.
The X350.5 and probably all current designs from PassLabs have a optimized powerstructure for higer impedences. They were not designed to behave like a almost perfect Voltage Source because the measured rating at 2 Ohms was even lower then the 4 Ohm rating where according to Ohm's law a double figure should be expected. (4 Ohm 612 Watts, 2 Ohm 604 Watts).
Another somewhat puzzling figure was the dampingfactor that was at lowfreqs 345 but at highfreqs it sank down to 129. I mention this because in different Pass/Threshold publications a point was made that a good damping behaviour was not a extreme high figure but one that was independent of the frequency and did not slope downwards when the frequency rises.
Maybe there is an explanation/designer choice for the above and is a 1.5 kVA Toroid (as stated by the magazine) for a 2 X 350 Watts @ 8 Ohm's sufficient. A 4 or a 5 kVa toroid as in Krell designs with the same specs at 8 Ohms make those amps a spinetwisting riskfactor when haulong them around of course.
The punchline was they found the reviewed X350.5 the best Stereo amp they ever listened to and that's that.
When no other amps were developed after the ML-3/ML-2's I would be very happy camper not having the knowledge and experience, after listening to the X250.5, that there's something better around. So all you folks be happy with what you have and never look, listen or long for something better, that's the advice here.
well - I'm cleverly proposing that all these gadgets may be shipped to my place, for proper disposal ;
as fee for my troubles , I'll pull few parts (here and there ) out , but nothing more ...
("ooops - ya see - I'm going to pull that fugly xformer from this lousy Papamp , but seems that rest of amp is simply glued to him ....... ! " )
as fee for my troubles , I'll pull few parts (here and there ) out , but nothing more ...
("ooops - ya see - I'm going to pull that fugly xformer from this lousy Papamp , but seems that rest of amp is simply glued to him ....... ! " )
@BrianEno,
whatever the reasons for your dismay of the Pass-amp are, the power capability for sure isn't.
Even in large rooms you will never drive the full 350W into 8R speakers, your neighbours would get deaf instantly.
You would wonder how little power you really demand - by the way you could find out yourself: get a multimeter and measure the voltage at the terminals as an crude estimate (during play). Take care!
Have fun, Hannes
PS: by the way a solid 300W amp is already usable for PA (small concert up to 30 poeple).
whatever the reasons for your dismay of the Pass-amp are, the power capability for sure isn't.
Even in large rooms you will never drive the full 350W into 8R speakers, your neighbours would get deaf instantly.
You would wonder how little power you really demand - by the way you could find out yourself: get a multimeter and measure the voltage at the terminals as an crude estimate (during play). Take care!
Have fun, Hannes
PS: by the way a solid 300W amp is already usable for PA (small concert up to 30 poeple).
IMHO, the point of having lots of power in the amplifier has little to do with what level of power you actually need to play music, but rather the level of distortion at a certain output level, plus the capability to cope with reactive low and transients.
I, for example, am not ready to give up my 100W monoblocks for its 25W equivalents, although 25W is already plenty.
Patrick
I, for example, am not ready to give up my 100W monoblocks for its 25W equivalents, although 25W is already plenty.
Patrick
Me neither - I'm myself currently finishing the pcb-artwork of a 100W amp
Why ever not? It's a hobby so I build what pleases me.
My previous post was just to give an hint to the original poster to look somewhereelse for the fault.
That guy throws around fearlessly numbers like 28A output current as if it was peanuts
Have fun, Hannes
Why ever not? It's a hobby so I build what pleases me.
My previous post was just to give an hint to the original poster to look somewhereelse for the fault.
That guy throws around fearlessly numbers like 28A output current as if it was peanuts
Have fun, Hannes
Nelson Pass said:Perhaps you should keep your ML-3's and be happy.
I believe it in that manner this allowable style, which a gentleman may allow to himself,.
The criticism attacking him was legitimate even, even not.
And this is not because of the others in this manner, but the man's own inner urge his reason.
Let somebody recommend something instead of the "in this manner" because I catch brain hemorrhage otherwise then now.
Nelson, (Grey ) I know it, that you from me you catch brain hemorrhage but what you believe about the film?
If it is not going some other way, then in a personal letter, if you
or ( you ) have a tiny time for me!
But if it is not, tells me, I will not take offence.
I know that you have many other tasks well, than to deal with idiots,like me.
I say thank you for the ones until now to you very much already.
Anyway anybody else relevant opinion interests.
The members' big part gets out from the humanity's more reasonable part mostly here because I believe it
in that manner.
The lord of old skies, already again this "manner".
I apologise to everybody, who from a reason like that like this, now or once, even in the future I hurt it.
But let me notice it because of that, quite injurious it, if peoples appearing reasonable pass over the other
man's opinion in silence.
I apologise to everybody once more, but somewhere away was needed let me say my thoughts.
Even then, if possibly these not too really to the object appropriate.
Let the moderators' lightnings strike down on me even because of this.
With respect:
Gyuri
The frightening thing about Gyuri's posts is that--though I can't understand a word of what he's saying--there are members here for whom English is a native language whose posts are even more opaque. Keep at it, Gyuri. One of these days I'm going to get the hang of reading your posts.
On the matter of current into loads and Pass Labs product...
At one point--and I believe it's still true--Nelson would bias a given circuit as hard as a given chassis would allow. For example, he might have two chassis sizes. You'd see a stereo version of the little one, then a higher powered monoblock using the same chassis. The larger one would also be available in stereo and monoblock variations. For two sets of metal, he'd be able to market four amps. Being able to buy face plates, tops, bottoms, heat sinks, and so forth in fewer sizes but larger quantities saved money on the production end. I haven't sat down and back calculated the rails/bias/heat dissipation of the current Pass Labs lineup, but I wouldn't be surprised if it worked out that he was still doing the same thing.
To beef up the sound quality is simple...bias the thing harder. But that might entail a larger power transformer (or using the same size transformer to run a monoblock) and very likely more heat sinking, either or both of which could push the amp into a larger chassis, which would cost more and require a higher retail price. It's easy to say that price is no object, but it is for many people and will become more so as the economy continues to deteriorate.
The obvious question then becomes, "Well, can I turn up the bias on my Pass Labs amp, myself?" And my equally obvious answer is to ask Nelson's permission first, as it's likely to void the warranty. Should you choose to do so on your own, keep an eye on the rail voltages (as well as the heat sink temperatures). If they collapse, you've gone too far.
Grey
On the matter of current into loads and Pass Labs product...
At one point--and I believe it's still true--Nelson would bias a given circuit as hard as a given chassis would allow. For example, he might have two chassis sizes. You'd see a stereo version of the little one, then a higher powered monoblock using the same chassis. The larger one would also be available in stereo and monoblock variations. For two sets of metal, he'd be able to market four amps. Being able to buy face plates, tops, bottoms, heat sinks, and so forth in fewer sizes but larger quantities saved money on the production end. I haven't sat down and back calculated the rails/bias/heat dissipation of the current Pass Labs lineup, but I wouldn't be surprised if it worked out that he was still doing the same thing.
To beef up the sound quality is simple...bias the thing harder. But that might entail a larger power transformer (or using the same size transformer to run a monoblock) and very likely more heat sinking, either or both of which could push the amp into a larger chassis, which would cost more and require a higher retail price. It's easy to say that price is no object, but it is for many people and will become more so as the economy continues to deteriorate.
The obvious question then becomes, "Well, can I turn up the bias on my Pass Labs amp, myself?" And my equally obvious answer is to ask Nelson's permission first, as it's likely to void the warranty. Should you choose to do so on your own, keep an eye on the rail voltages (as well as the heat sink temperatures). If they collapse, you've gone too far.
Grey
OT: Translation...
Does anyone else think Gyuri's quite enigmatic posts are the result of an automatic, perhaps computer based translator?
The idioms and vocabulary do not seem typical of speakers for whom English is a second language.
I wonder if he is having as much trouble understanding us...
My 2c
Stuart
Does anyone else think Gyuri's quite enigmatic posts are the result of an automatic, perhaps computer based translator?
The idioms and vocabulary do not seem typical of speakers for whom English is a second language.
I wonder if he is having as much trouble understanding us...
My 2c
Stuart
He is referring to the movie Zeitgeist, which is being released liegitimately
on the web tomorrow. If you have 2 hours, it looks very interesting.
Going back to the subject of current from Pass amplifiers, I suggest that
maximum current output is obtainable from the XA160.6 and XA100.5, as
these have twice the output stage per channel and twice the output current.
of the same-chassis-size stereo amplifiers. My data indicates nominal
limiting at 40 amps without regard to output voltage.
on the web tomorrow. If you have 2 hours, it looks very interesting.
Going back to the subject of current from Pass amplifiers, I suggest that
maximum current output is obtainable from the XA160.6 and XA100.5, as
these have twice the output stage per channel and twice the output current.
of the same-chassis-size stereo amplifiers. My data indicates nominal
limiting at 40 amps without regard to output voltage.
@h_a
My neighbours do not get deaf with 350 Watts @ an eight Ohm speaker cause mine is 82 dB/1w meter 4 Ohms nominal with dips approaching 1 Ohm electrostatic one. Psycho-acoustically doubling the soundpressure takes ten times the power so that gives a maximum of 110 dB (given the measured 600 Watts @ 4 Ohms for the X-350.5)
I never expressed any dismay with PassLabs products in this thread. I just wondered why this this amp that sounds so wonderfull (first posting from me "The sound was very good vocals moved to the front there was depth and musicality at last.") got his ampmeter very quick at the rightcorner of its scale given his 250 Watts rating. I think I know now why this so after reading the Stereoplay review, especially the labreport, of the more powerfull X-350.5.
Passlabs seems to be tailored for an optimum power-envelope between 8 and 4 Ohms and not below that point for probably good reasons I would like to know.
Reading the article 'Power Supplies: Commentary for Consumers' from Nelson Pass where he makes a stand for a big powersupply:
First, third and fourth alinea at the 'Conclusion' :
"So what have we learned here? In general it takes big money to buy the big hardware to make really good power amplifier supplies.
Engineering being the science of compromise, each manufacturer
draws their own cost/benefit line, and it has been my experience that most manufacturers are quite conscientious about this. The degree of sophistication and massiveness of a supply has the context of the price of the product, and your expectations should be scaled accordingly.
As a consumer, you want the best sound you can get. You can
accomplish that through critical listening. As a secondary goal, we all like to get what seems to be good hardware value, and we want to know that that the manufacturer has actually put some real money into the product which costs a small fortune. If you can read the specs or look under the hood, the power supply, being one of the most expensive parts of the amp, usually is a good indicator. It should be the biggest and heaviest part of the amplifier."
I looked under the hood of many similar priced designs Levinsons (like a no. 333) , Rowlands (like model 5 or 8) and Krells (like a KSA 300s and FBP 600) and I can read the specs and Nelson Pass is right when he states that "Engineering being the science of compromise, each manufacturer draws their own cost/benefit line, and it has been my experience that most manufacturers are quite conscientious about this."
I'm just curious where he has drawned the line when it comes to powersupplies in his designs compared to the above mentioned.
I think that's a valid and legitimit question and there's no need to get defensive or annoyed about this matter.
BrianEno said:
We deliberately design the amplifier to shunt the front end to the output
when the drive voltage to the follower output stage exceeds twice the
total bias + 0.7V. This keeps output devices from exceeding their DC
SOA figures, and this way we get very few of them back for repair.
Some manufacturers emphasize the arc-welder capacity of their amplifiers -
we specialize in sounding as good as possible into reasonably ordinary
speakers. This is of course an arbitrary decision on our part, but we are
content with it. There are more powerful amplifiers on the market, and we
are happy to see them get their share of business as well.
Thanks Grey and Nelson Pass for the explanations.
Of course I'm not in the market for arc-welding amplifiers. Your referring probably to a insane demonstration, conducted by Mark Levinson himself or Thom Colangelo to show the stiffness, of a ML-2 or 3 it was I believe, of their powersupplies) I tr to find a good sounding and for me technically matching amp.
I heard lots of good things about the Passlab products and I have had good experience with Threshold Stasis designs from the eighties.
Maybe I should sell my Acoustats and find me a more sensitive and sensible (regarding the load) speaker although I bought one of the last pair of 2 + 2's in 1991 and kept them till now never felt the inclination to replace them as with other equipment.
Of course I'm not in the market for arc-welding amplifiers. Your referring probably to a insane demonstration, conducted by Mark Levinson himself or Thom Colangelo to show the stiffness, of a ML-2 or 3 it was I believe, of their powersupplies) I tr to find a good sounding and for me technically matching amp.
I heard lots of good things about the Passlab products and I have had good experience with Threshold Stasis designs from the eighties.
Maybe I should sell my Acoustats and find me a more sensitive and sensible (regarding the load) speaker although I bought one of the last pair of 2 + 2's in 1991 and kept them till now never felt the inclination to replace them as with other equipment.
Supposedly there was a demonstration using a Phase Linear to drive (as I heard it) a small air conditioner. Pop a 60Hz signal in the front and hook up the air conditioner to the back.
Stunts like that are nifty in their own way, but unrealistic...at least for me, because I don't care to listen to air conditioners. Or welding rigs, for that matter.
Grey
Stunts like that are nifty in their own way, but unrealistic...at least for me, because I don't care to listen to air conditioners. Or welding rigs, for that matter.
Grey
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