Bryston VS Pass XA

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Hi,

I'm with Peter, there is no absolute reference to compare the sound chain to, as long as all the links are imperfect . There are cumulative errors and only very long tests can give a clue about which can be the weakest one. It's like a hydro turbine and generator set. There is no way to measure the efficiency of each machine when both are operating. Imposible.
Said that, I think that is up to everyone to choose which approximation is closer to their liking, and here I'm with Nelson.
But obviously, the amp designer target should be to make an absolute instrumentation amplifier, that outputs gain times input. And the turntable manufacturer, and the loudspeaker builder, etc. I'm afraid is kind of imposible, but I'm a bit ignorant to insist on this point.
There is a very interesting paper by Daniel H. Cheever, about methodology for measuring audio amps. I suppose most of you know about it, it's worth reading. I can zip it here if someone's interested on it.
And of course, only with acoustical music you can use the live event to compare (with some caveats).
Upupa, have you heard any music in D moll? ;)

What is certainly true, is that I haven't had yet the feeling of a violin (like the one I have) through a hifi chain. I haven't build yet a pass one so there is still hope. BTW and sorry for escaping the thread, my last amp is a discrete mosfet one that clearly outperforms my gainclone. Yes, the GC I couldn't distinguish from my AV Denon.
 
Most of schematics and constructions presented in magazines are wrong and have often insufficient directions for building. When an inexperienced man do it, mostly is with results disapointed, which lead him to the simply and easy to build connections, such are all Zens and Alephs etc. . This schematics are so simply, that build it wrong is practicaly impossible. 'Cos they have not any " fatal errors ", plays better than many others and man get erroneous opinion, that it is " state of art ", because to this time don't listen anything better ones. Discuss on " Pass pages " about nonadvantages of this connections is like commit suicide - here are too many fans which accept his thinking. I belive him, that they have enjoy by listening music thrue amps which are build by own hand and I wish him it :cool: .
 
Hi Raka,
I am interested in the Daniel Cheevers paper and even more curious if you are female or not;)
I regularly gauge my ears going to live concerts and even buy CD's of the performance I just heard. Back home I play the CD to get an idea of the performance of my set.
I admit it is very difficult to get the delicacy of the violin reproduced in your home and the sparkling, effortless sound of the clavichord.
With the right clock the SACD of my friend is better in this respect but CD sounds more "romantic".:)
But I remember a concert with a soprano that had such a loud voice I did barely here the clavichord in the background. On the CD the sound was nicely balanced!:)
 
You can try this:

http://web.mit.edu/cheever/www/cheever_thesis.pdf

Elso, do you know how can I change the clock of my turntable? ;) BTW, the answer is yes, but it's irrelevant.

It's not unusual to find more "balanced" sound in recordings, and if properly done, you can have a better seat in the hall at home than at the live concert, but you loose most of the musical emotion.
There were many directors that refused to put the music in a can, can't remember the actual name but one of them stated that the recorded music was the beginning of the end.
 
Clock for turntable

Raka said:


Elso, do you know how can I change the clock of my turntable? ;)

Hi Raka, Hahahaha:D , if your turntable does have a clock it might be OK. I remember the Technics SP10 had a Colpitts oscillator just as my clock. Yet many die-hards prefer a beltdriven tabe. They never could convince me.......Now we have even beltdriven CD players (Burmester, CEC f.a.)
;)
In the past I made live recordings with a Tandberg 10XD on 19 and 38c/s two track. When playing these tapes I was stunned by the detail, dynamics and slam and naturalness of the sound. A lot is lost in the process of making LP's and CD's, I can only conclude.

Thanks for the link to the thesis. A lot of interesting reading!;)
 
I’m still thinking about X vs. XA and then an off topic idea came to me. In the XA diff pair why not use a simple circuit to regulate the temp of the diff pair. Something in a t0-220 package. Maybe an LM35 to Sens the temp and an to-220 power resistor as a heater. This would help stabilize the dc off set.
 
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Upupa Epops said:
Most of schematics and constructions presented in magazines are wrong and have often insufficient directions for building. When an inexperienced man do it, mostly is with results disapointed, which lead him to the simply and easy to build connections, such are all Zens and Alephs etc. . This schematics are so simply, that build it wrong is practicaly impossible. 'Cos they have not any " fatal errors ", plays better than many others and man get erroneous opinion, that it is " state of art ", because to this time don't listen anything better ones. Discuss on " Pass pages " about nonadvantages of this connections is like commit suicide - here are too many fans which accept his thinking. I belive him, that they have enjoy by listening music thrue amps which are build by own hand and I wish him it :cool: .

I think you are right, and I can build complex good sounding
(and certainly better measuring) amps, but I prefer to try to
coax (read: seduce) DIYers into climbing that initial wall of their
first project. Besides, I am often surprised that the really
simple circuits perform as well as they do. (It helps a lot if you
have an easy-to-drive loudspeaker ) :cool:
 
LBHajdu,
What...these amps don't generate enough heat already?
When I was building the prototype of the Aleph-X I originally used heat sinks for the front end. Didn't really need them, just had some at my elbow and thought,"Why not?" Once it became clear that the thermal behavior was going to be a problem, I took them off and the amp settled down quite a bit. Eventually, if you follow this to its logical conclusion, you end up with the input MOSFETs either back-to-back or insulated from air currents (down against the PC board works pretty well). In the first case they may vary, but they track each other so it cancels out. In the second you're just trying to keep them from varying at all.
There was an intermediate stage where I considered something similar to what you're describing, but never followed through. It should work, but I'm not sure that it would be worth the effort. As I recall, my reasoning at the time was that the heater element would presumably be set to test and cycle fairly quickly. Do that often enough and you're likely to end up with a subtle audio frequency effect superimposed on the signal as the MOSFET characteristics change with the temperature. On the other hand, if you slow it down, you might as well accept the slow drift that you get with the regular ways of doing it.
Note that there's a precedent, in that some HP oscillator circuits use an "oven" to maintain an elevated temperature, with the intent that the frequency they generate is more constant.
You're welcome to try it.

Grey
 
The one and only
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Paid Member
Been there with the heater. It seems to work best on
the "VAS" transistor, that device which is the gain device
coming off the diff pair which generates the full voltage swing
in many amps. It is usually set at high gain, and is a great
spot for thermal feedback control. I simply used a resistor
bonded to the device and ran current through the resistor
to heat it. Gives perfect isolation and a nice slow time constant.
 
Raka said:
What is certainly true, is that I haven't had yet the feeling of a violin (like the one I have) through a hifi chain.

Hi Raka,

Your post bring a couple of link to mind that you may find interesting (if you haven't seen them already).

Gabriel Weinreich, Professor Emeritus at the University of Michigan and pre-eminent figure in the world of musical acoustics: "I still don't know the 'Secret of Stradivari'"
http://www.msen.com/~violins/news/strad/apr00/Gabi_strad.htm

Directional tone color loudspeaker Patent
http://patft.uspto.gov/netacgi/nph-...&co1=AND&d=ptxt&s1=boulez&OS=boulez&RS=boulez


JF
 

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Nelson Pass said:


I think you are right, and I can build complex good sounding
(and certainly better measuring) amps, but I prefer to try to
coax (read: seduce) DIYers into climbing that initial wall of their
first project. Besides, I am often surprised that the really
simple circuits perform as well as they do. (It helps a lot if you
have an easy-to-drive loudspeaker ) :cool:


Well....something went wrong on the way. I believe you are referring to the ZEN projects. If so, you are succesfull on the getting DIY'ers over the wall and make their first project.

The un-succesfull part is that the first project tends to also be the last in many cases. The Zen V1 have made a first project for many, i know a few who have made such, a lot of those have actually ended up with it as the "final" amp, and been quite happy with that.

A friend of mine who made the Zen V1 by the book with average components, when asked if he wasnt going to make any improvements, replied :

The level of this amp is adequately high, that any improvement would be waste of time and money, i sure wouldnt be able to hear it since its down in the petty improvement department.

The only thing he is going to change is the boxes, since he didnt pay much attention to the looks, expecting the amp to be experimental and not the "final" amp.

So in order to get people into DIY audio, you gotta mess things up a bit ;)

Magura:)
 
LBHajdu said:
I'm considering building the Bryston 3sst amps. It’s for music and HT, mostly rock. the Brystons sound clear with extended highs and a very good bottom end. They don’t have the warmth, and silky smoothness of the original Alephs. However I don’t know if I want that sound. For HT it would play down seems like, for example the seen in the original Matrix where they where braking marble tiles in the lobby of that sky rise.

Now enter the XA. It has improved bass and highs. This is an $18,000 amp compared to the $2,500 Bryston. Does this amp do everything the Brystons do and more? Or is the XA made to appeal to a special kind of listener.

The brystons and Pass XAs are some of the best topologies I found online. I have both there schematics. They both employ creative solutions for lowering distortion. The XA has higher distortion and higher heat:hot: . But is it worth it? Beside the heat sinks, they cost about the same to build.

Opinions are welcome by everyone, but hopefully by people who have actually lisined to these amps.

Leve Hajdu


Hi Leve,

Maybe a bit late, but this is my highly subjective opinion:

Three years ago I saw a second-hand Bryston 3 (about 12 years of age). I took it home and listened to it.
It was reasonably musical, powerful and pleasant to listen to. On the other hand I found it a bit rough sometimes.

Someone told me that the Brystons had been updated over the years, and that the newer ones sounded better.

That gave me the incentive to try a newer model. I took a new Bryston 4 home and listened to it. It was already broken in by the shop.

It was an strange experience: I had never heard a mosfet amp sounding that umusical!:bawling:

It was extremely bright, thin, pale, flat etc...
You could hear nothing of the acoustics of a recording. There was just this flat one dimensional synthesizer like sound.

Just to doublecheck I too this amp to a friend of mine with two large ESL's (the largest Finals). There our impression was exactly the same as at home.

I asked the shop-owner whether someone could be wrong with this very amp. He said that he too found that they had become extremely unmusical over the years... A sad story:mad:

I do listen to Aleph 5 nowadays, and while I do love thair sound, I do understand that others may have different taste. At the time of listening to the Brystons, however, I had never listened to Pass amps at al, so I could not have been prejudiced because of Passlabs.

If you want something less warm and tubelike in sound, why not go for the normal X-types. They sound a bit more solid-state than the Aleph's or the Aleph-X's. You also get more efficiency and power.

Regards,

Lucas
 
Never heard a Bryston I could own as anything but a sub amp.

CAVEAT on Bryston amplifiers.

They are used by the CBC recording studios (Canadain Broadcasting Corporation, the Canadian government runs the outfit).

The joke among the CBC engineers is that if they want to do any recording on Monday, they turn the Bryston amplifiers on, on the Friday before and leave them on all weekend.

There is a reason for this..

Bryston amps are tested initially after construction, and then set to be as close to spec as possible to keep them stable and then run for THREE DAYS continuously and 1/3 power, on/in a giant loading rack/room.

They are taken out, still hot..and under those thermal and running conditions, are tweaked for the best null in crossover distortion and DC offset. This, while they are still hot and running.

What this does to the sound of a Bryston is that they then will NOT sound GOOD until the THIRD DAY of continous NON STOP-NON-INTERRUPTED RUNNING. It is very strange, but it can be heard. Sudddenly, over a period of about 20 minutes, on the their Third day... Bryston power amps will suddenly sound ...good! You can actually hear it happen. (the same effect occurs when calibrating CRT projectors, the calibration time frame and proceedure will re-occur each time the unit is turned on)


Until that moment happens, they sound harsh.

This means, give a Bryston three days or more before you attempt to evaluate it's sonic qualities.

Bryston themselves tell you to never turn off a Bryston amplifier. They are designed to be left on 24/7.
 
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Magura said:
Well....something went wrong on the way. I believe you are referring to the ZEN projects. If so, you are succesfull on the getting DIY'ers over the wall and make their first project.

The un-succesfull part is that the first project tends to also be the last in many cases. The Zen V1 have made a first project for many, i know a few who have made such, a lot of those have actually ended up with it as the "final" amp, and been quite happy with that.

I find that eventually most of these guys will get the itch again.

I remember when years ago Joe Sammut (now president of
Pass Labs) threw out his stacked Dayton Wright speakers,
all the electronics, and his Ampex ATR 100 tape deck, and got
a table radio. After a few years, though, he was back in the
fold, with a vengeance. :cool:
 
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Re: Re: Re: Bryston VS Pass XA

planet10 said:
The brystons have bi-polar outputs....

That's what I thought. On the other hand, if Bryston
had switched over to Mosfets and run them at the lower
bias they used with the bi-polars, that would be a possible
explanation. It's my experience that Mosfets need lots of
bias, and a lot of the faults of the early designs were the
result of designers simply dropping Mosfets into the circuit
as if they were bipolars (early Hafler = good example).
 
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