[MASantos]

Regarding the portable amp, is the body actually magnesium? 
 
Note on the ridustor website:

Due to designer decision the XJ03 ( as well as all the new portable products ) is available only in electric blu anodized aluminum body, with engraved graphics and silver color panels.
Regarding design: 
 
Sovkiller,if you need to tighten a hex screw, you use a hex screwdriver. If you're a surgeon you use a scalpel to cut flesh, you won't use a kitchen knife, just because you like the feel of holding one better. If you're a lifeguard you use sunglasses because it reduces the flare of the sun on the surface of the water.
Somethings are meant to be done one way because it is the correct way to do it, not because of being better or worse, or right or wrong. 
Example: IC based amplifer design theory, the vast majority of amplifier designers out there and most importantly, the IC developing companies themselves state that the use of ground planes is fundamental and of paramount importance to the good behavior of the circuits and should not be overlooked. I can't understand why Rudi didn't use one on his portable amplifier pcb.
 
I'm not comenting on the sound, as I've only heard his products once and not long enough to form an opinion, but some of his design and building practices and standards are not to industry standard.

 

[Sovkiller]

 
Quote:

Regarding the portable amp, is the body actually magnesium? 
 
Note on the ridustor website:

Due to designer decision the XJ03 ( as well as all the new portable products ) is available only in electric blu anodized aluminum body, with engraved graphics and silver color panels.
Regarding design: 
 
Sovkiller,if you need to tighten a hex screw, you use a hex screwdriver. If you're a surgeon you use a scalpel to cut flesh, you won't use a kitchen knife, just because you like the feel of holding one better. If you're a lifeguard you use sunglasses because it reduces the flare of the sun on the surface of the water.
Somethings are meant to be done one way because it is the correct way to do it, not because of being better or worse, or right or wrong. 
Example: IC based amplifer design theory, the vast majority of amplifier designers out there and most importantly, the IC developing companies themselves state that the use of ground planes is fundamental and of paramount importance to the good behavior of the circuits and should not be overlooked. I can't understand why Rudi didn't use one on his portable amplifier pcb.
 
I'm not comenting on the sound, as I've only heard his products once and not long enough to form an opinion, but some of his design and building practices and standards are not to industry standard.

You are absolutely right, that is why many designers will never even consider the use of an IC for audio amplification to begin with, as they believe all of them have compromises...Honestly do you really believe that there is a right or a wrong way, and that any designer that have read a couple of books on the subject does not know how to design an amp or the theory behind it...Audio amplification have been here for how long, half a century? There is always a reason for everything, and even while I consider myself on the intelligent side, I could not speak for what other person does, or believes, or the criteria behind any design...One thing is sure, and again, if there was an optimal design, we were all listening to it, and this forum would never existed...Honestly a design of an amp is something that I do not want to get involved in, I just want to have one that sounds good to me, and I found it...period, good bad, I do not care, I like the way it sound and make me happy, is that so hard to understand?
 
 
What I have learn all these years, is that electronic design is one thing, and how you enjoy the music, and how it is supposed to sound to your ears, is another completely different...and trust me that I have heard too many rights to sound just plain wrong, and too many wrongs to sound beautifully, that is why you see nowadays very simple tube amps designs, with huge distortion figures, and people still like them...and pay for them good sums of money, while others with a lot better figures are still in a shelf in Best Buys, and we do not even look at them...
 
Maybe is just my ears...but why not waiting till you hear the amp, maybe is a piece of crap to your ears, but maybe it will make you change your mind about what is right or wrong...
 
None of the amps I have heard from Rudi yet, have disappointed me, I like one better than others, but all have sounded right to me...otherwise I would l have changed my RPX33 long time ago...and trust me that as soon as I found one that sounds better in my budget I will get it...the RP10 or the RP1000 are both out of my league...the only two I have enjoyed more...
 

 

[spritzer]

Rudi was in fact one of the most vocal anti IC people around.  He even attacked designs as being inferior because they used opamps regardless of the small issue of those opamps never being in the signal path.  One must wonder about the sudden change of heart...  As for IC's in general, they will always be a compromise.  There is no way around this and you can always build a better circuit with discrete components.  A proper film cap will always be better then something found on a chip, ditto for 0.1% resistors.  

 

[Sovkiller]

On thing I have learn in my life, and that is very simple, the more you get involved in a given field, the less you will like the offers of the market...Ones are crap, others are overpriced, and at the end you will never find peace of mind getting them...

 

[Sovkiller]

If there is any trusty member willing to review it, just gimme a shout...I may get mine in a few days, otherwise maybe I could take it to the upcomming NY fall meeting.. 

 

[rosgr63]

Skylab, or marroyo would be very reliable reviewers.

 

[oqvist]

Send it to Spritzer. More fun that way

 

[rosgr63]

Quote:

Send it to Spritzer. More fun that way

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Provided he doesn't open the amp case but only listens to it!

 

[winzzz]

^ whats wrong with oppening the case ? scared bout what you're gonna find ? supriseee...maybe you'll find a cmoy inside the "what rudi called magnesium" case

 

[spritzer]

I open up every amp that comes through here these days and publish the schematic.  That's how all reviews should be handled, at least that's how the few good magazines do it. 

 

[Sovkiller]

A person who is more worried about how an amp is designed and build, and what topology is used, is unable to enjoy music, or even sound, to enjoy schematics is one thing, and to enjoy music is another very different...if you want to review an schematic, you know the drill, if you want ot review an amp, you also know whon could be able to... 
 
It will be good how to see customers opening all comercial electronic devices in reviews, to see later on how the warranty was voided, electronic devices are intended to be used, not to watch inside them, if you want to watch, get a nice painting... 
 
 
In the last case, I do not care a single bit how it is rated as desing if I enjoy the sound of it, electronic ignorance is a bliss I still have...LOL...and try to keep... 

 

[Nebby]

In the older days, the schematics of the device would be included in the manual. Shame companies don't do that anymore even though many designs are just derivative works.

 

[Uncle Erik]

Very true, Nebby.

That goes back to a time when most houses had a workbench in the garage and you'd fix things at home.

Some amateur radio gear still comes with schematics - I got full documentation with my Icom. Also got it with the Si2A3 and am pretty sure I have the schematics for the CJ PV2 and MV52 around somewhere. I like it since consumers should be able to diagnose and repair things themselves.

 

[LevA]

Quote:

A person who is more worried about how an amp is designed and build, and what topology is used, is unable to enjoy music, or even sound, to enjoy schematics is one thing, and to enjoy music is another very different...if you want to review an schematic, you know the drill, if you want ot review an amp, you also know whon could be able to... 
 
It will be good how to see customers opening all comercial electronic devices in reviews, to see later on how the warranty was voided, electronic devices are intended to be used, not to watch inside them, if you want to watch, get a nice painting... 
 
 
In the last case, I do not care a single bit how it is rated as desing if I enjoy the sound of it, electronic ignorance is a bliss I still have...LOL...and try to keep... 

 
wasn't it that logic that lead to the singlepower fiasco here in head-fi? someone decided to take a peek under the hood only to find out some of them were actually ticking bombs.....I'm not saying this is the case here, but I don't see anything wrong with people genuinely want to see what they have bought. 

A person who is more worried about how an amp is designed and build, and what topology is used, is unable to enjoy music, or even sound
wow..according to this logic, anyone who is interested in a hobby and well informed are actually incapable of enjoying it...so if you are interested in cars and knowledgeable you pretty much don't enjoy driving..or if your are a recording technician and worried about sound quality, you most likely don't enjoy listening to music...should I go on? the fact is if something is your hobby, you want to learn more, understand how things work precisely because you enjoy it so much....
 
to be honest, you seem like you really don't have that much faith in the product you are promoting here by giving reasons why you should not be interested in the design..
 
btw, here's an excerpt from rudistor site:
 
"XJ-03 MKII  [size=x-small]is not just "another  portable amplifier" it has been designed to be really  different. Although it shows a traditional external design under his  solid magnesium body it hide a powerful sound engine and some smart solutions, making it easy to use, flexible and hassle free"[/size]
 
so it's ok for the builder to claim the importance of design, but not us???

 

[spritzer]

Of course people should look at the schematic since that's what you are listening to after all.  There is no magic to amp design but there are so many pitfalls and stupid design decisions to make.  There are also clear compromises made due to cost constraints.  Take the two amps I've been working on this week for instance, both Stax units, the SRM-727 and the SRM-300/310. 
 
With the former one the Stax engineers did a lot of things right but then they did something stupid, left the output stage out of the feedback loop.  This is clearly a deliberate design choice and is highly touted in their brochures but there is no way in hell for the amp to remain linear into transducers loads and have low distortion at these power levels without feedback.  The amp is also unstable so Stax lowered the gain by 6db.  Luckily, both of these issues were easy to fix, replace one of the feedback resistors (4 phases in the amp so 4 resistors in total) and move it to a seemingly unused terminal makes the amp stable and the gain issue was fixed by removing four 560R resistors and replacing them with 200R units.  The end results are a transformed amplifier, no more uneven frequency response, 10 times lower distortion and enough clean power to drive any of the Omegas. 
 
The latter is a clear case of cost cutting.  The basic design is the same as the SRM-001 (AC-coupled and with a opamp front end) but scaled up and fitted with a nice regulated PSU and a R-core transformer.  This amp was never intended for use with anything but a Lambda so Stax used tiny 0.01uf output caps which means you get severe bass rolloff with the Omegas.  Now you can't fit any larger caps on the board but with some care I fitted 1uf caps and now this amp sounds just fine driving the Omegas.  Another example of cost cutting was the input stage opamp, LF353, which isn't bad but you can easily do better and so is the volume control solution and now they implemented a balance control.  Guess what these mods did to an already good design, they made it better. 
 
Now while both these designs could be improved they are both very good and heads and shoulders above what people call "reference quality" in the dynamic world.  Bottom line is quite simple, the design matters as it directly influences what you hear and how you hear it.