[Sovkiller]

 
Quote:

 
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???

Wait...wait...wait...I'm not promoting anything, I do not even have any reason for it, not anymore...maybe other than personal pride....I do not even know how this MKII will sound, nor anybody I know off, except Rudi, I have the prior version, and it sounds to me second to none, and I have tried almost every single of the best portable amps out there, more than a few of them, even owned a few, and I'm assuming that this one will not be an step back...just that...
 
But we all know also, that for some shady reasons, other amps from Rudi have been severely criticized by persons who had never owned, or listened them, nor know anything about their designs, or schematics (as they have never been posted as far as I know) and we had several threads closed for that same reason, arguments with total lack of evidence, and I encourage everybody to listen them...period...I'm happy, now, my question: Are you?
 
Just that...I want everybody to feel like me...period...
 
The Singlepower fiasco, was more because of the lack of support, and other issues related with the customer service, and the total lack of answers at the end, and some money issues, than because of the designs themselves (even while Dr. G was very severe criticizing them, and even some funny pics were posted) but even though we still have a lot of happy owners of those amps, for weird that it seems, that have not even think in modifying those amps...and they do sound good for many...(not to my ears...OK?)  

 

[Uncle Erik]

Sov, Singlepower had some real issues with poor transformer choices, not to mention the one amp that had a couple of wallwarts stuck inside a fancy box.

 

[kevin gilmore]

We are now well into round 2 of singlepower repairs.  People selling off poorly repaired units to other people, and
those units now failing.  The problems with transformers on the extremes is well known, but now mpx3's and supra versions
of same with people putting 6bl7's in as the output tubes, and smoking the transformers and the filament supplies.
Yep they sure sound good when they work. In many cases people are paying more to repair them, than they paid
for them in the first place. And i know of 2 of the electrostatic amps with the gas tube power supplies that are
completely fried, and not repairable for any reasonable amount of money.
 
I now have schematics of every single rudistor product from the last 5 years. Including the rp010. And pictures
of the inside of the box of boxes.
 
All of the things can be split into just 2 designs. (dynamic amps)
 
1) opamp as the front end, darlington npn transistor output stage, either resistor or lm317 as the current sink, DC coupled
and oodles of feedback.
 
2) a jfet, or a tube as the front end, darlington npn transistor output stage, either resistor or lm317 as the current sink, AC coupled
and NO feedback.
 
balanced versions are just 4 of the same amplifier instead of 2.
 
pictures of the insides of the current portable have been posted elsewhere.
Just a single dual opamp. Nothing more, no different than a cmoy.

 

[Sovkiller]

 
Quote:

pictures of the insides of the current portable have been posted elsewhere.
Just a single dual opamp. Nothing more, no different than a cmoy.

Would you mind to tell me which OPamp? Are you sure it is a dual OPamp...??? Not that I have anything on the C-Moys, some of them actually sounded better to my ears than your Dynalo I received from Justin....and paid more than $500.00 for it...at that time.... 

 

[Sovkiller]

Quote:

I now have schematics of every single rudistor product from the last 5 years. Including the rp010. And pictures
of the inside of the box of boxes.
 
All of the things can be split into just 2 designs. (dynamic amps)
 
1) opamp as the front end, darlington npn transistor output stage, either resistor or lm317 as the current sink, DC coupled
and oodles of feedback.
 
2) a jfet, or a tube as the front end, darlington npn transistor output stage, either resistor or lm317 as the current sink, AC coupled
and NO feedback.
 
balanced versions are just 4 of the same amplifier instead of 2.
 

Wow, very informative, do you really have the schematics or just a general idea of the topology? Good to know, that someone has them, and it seems that you indeed have more information about Ruditor designs than me and my friend the engineer that used to repair/mod/upgrade the few rudistor amps that were sent in (as a curious info, Rudi never sent us any schematic that were not absolutely necesary, nor that we asked for them neither...of course we never repaired any RPX33 and up amps, just a couple of NX33 and one NX02...) Would you mind to tell me how did you get them, did he send them to you, or was just a reverse engineering from a picture posted online?  
 

 

[Sovkiller]

 
Quote:

Sov, Singlepower had some real issues with poor transformer choices, not to mention the one amp that had a couple of wallwarts stuck inside a fancy box.

Sorry I was not aware of those, to be really honest, I lost track of SP amps after I heard of a few scams, if that is the right word to use, but good to know, that I was not completely on the wrong side...as I never liked them personally, the sound was not my cup of tea...

 

[spritzer]

Ahh the issue of the magic opamp which is so good that is somehow makes a 600$ cmoy truly great?  The main issue here is that Rudi has zero credibility in the headphone world so does anybody honestly believe he forked over the tens of thousand of dollars needed to fund a custom designed unit?  You can get opamps for next to nothing but most of them are designs from the 80's so any R&D costs are long gone. 
 
Now you could get a custom logo on an opamp for a lot less (Adcom used custom OPA27's with their logo in the 90's) but that will also require a huge order unless you are dealing with some cheap Chinese knockoff. 

 

[Uncle Erik]

Sov, if you have an item or good photos, you can work out the schematic by hand. I've got an oddball GE console radio from the late 30s that I've found very little information on. I was able to draw the schematic. I'm sure Kevin has no trouble doing the same.

 

[kevin gilmore]

Well here is one of the rudistor schematics.
http://gilmore.chem.northwestern.edu/nx02.pdf
The power supply is dual simple resistor,zener and a 2n3055 pass transistor for the +vcc supply,
and the same thing with a 2n2955 for the -vcc supply. This seems the same on every single unit
even the rp010. Whats funny on the nx02 is that rudi uses a pair of expensive dual opamps, but
only uses one side of each. The other opamp has all the wires completely unconnected to anything.
Which is really bad from a noise issue.
 
I have a dozen more that would need a bit of cleanup before uploading.
Speaking of uploading, 11 pictures just in on another singlepower unit.
Once i get the permission to post, i will post those too.
 
At this rate i'll be doing singlepower support for the rest of my life

 

[Sovkiller]

Quote:

Sov, if you have an item or good photos, you can work out the schematic by hand. I've got an oddball GE console radio from the late 30s that I've found very little information on. I was able to draw the schematic. I'm sure Kevin has no trouble doing the same.

Erik in this particular case, Kevin or whomever work out that schematic, had indeed some troubles doing that...That schematic posted there is plain wrong, some of the resistor values are wrong, and also has other errors, I do not think that you can make this schematic work like that ever, just try it yourself if you want, it is nothing complicated, and will not be for you...but whatever...BTW I do have this schematic around, and we even assembled one of those amps locally for a meeting...
 
So I think that at the end reverse engineering is not that easy at it seems, at least not for some smart guys. Not even for a simple amp like that...but I will render my case, at the end, I have no interest in keeping making this thread worst, all the opposite, so guys you can keep on bashing in peace, I'm out, whomever may be interestedin reviewing my personal amp when I get them both IEM and amp, and after playing around for a few days, you know how to get in touch with me... 

 

[rosgr63]

Sovkiller, I wonder how one can make a schematic by looking at the insides of a RPO10B with those metal enclosures.
Unless of course they have bought it, in which case.....

 

[spritzer]

If there are errors in that schematic then the reason is quite simple, the amps sold to people were not built correctly.  That is drawn up from a production amp and it is correct. 
 
For the record, it is very easy to retrace the Rudistor amps.  They all use single sided PCB's with no ground plane so all the traces can be spotted from above.  Look up the datasheet, read the code on the resistors and you have the circuit. 
 
Quote:

Sovkiller, I wonder how one can make a schematic by looking at the insides of a RPO10B with those metal enclosures.
Unless of course they have bought it, in which case.....

 
No, the owners were worried about being scammed so they opened up the internal boxes and sought help to figure out what they were looking at. 
 

 

[kevin gilmore]

my bad, slight error in the schematic.
but it would work as shown.
 
here is another version with the graphs that prove it works.
http://gilmore.chem.northwestern.edu/nx02a.pdf

 

[Yale]

For what it's worth, here is my experience with a recently purchased Rudistor XJ03 MkII.
 
I was considering to purchase another portable amp after reading Skylab's fantastic reviews on the subject and spent the past few weeks auditioning a few amps. The novelty and decent SQ of the XJ03 drove me to pony up an additional $150 over my original budget for this purchase. In general terms, I appreciated the lushness and decent breadth of the sound stage but wasn't crazy about the relatively shabby workmanship of the unit, which I admit I compromised for during the excitement of purchase.
 
 
When I took it home, the following happened:
 
One side failed to work.
 
I though maybe it was the charge. I charged for 4 hours. Nothing. Just one side failed to produce sound. It worked at the store, but not at home. I may have just been unlucky with my unit as others have experienced similar quality problems in the past. Unfortunately, I have lost confidence in the brand.To make a long story short, the store was kind enough to exchange it for another brand (my original intended headamp), so in the end I am still a happy customer.
 
Some observations I would like to share with you regarding the XJ03:
 
Three different types of screws hold together the case. Why three? 
Bottom-left back panel screw protrudes so that if you are using wide-base connector such as ALO, etc...you will need to take that screw out, or else in my case, the manufacturer tapped the hole so that a semi-flush mounted screw can be used.
Front and rear panel/edges/finish was visibly rough to the touch.
The feel of the  volume knob was inconsistent from unit to unit. Some felt smooth, others sticky and rough.
The case is DEFINITELY NOT MAGNESIUM! It is made of extrude aluminum despite the contradictory claims on the manufacture's site.
The model comes in two separate gains format - high gain model and a low one. There is no switch to go from one to the other. You must decide the type of headphones you'd be using before purchasing it.
What is in the package? - a 3.3MM to 3.5MM jack, a charger made by "Fu Yuang". No instructions, no warranty cards.
The manufacturer claims it to be "Created in Italy" on the back panel and "Handcrafted n Italy" (not my mis-spelling) on the box -- I'll let you decide if it is so. Why not just state "Made in Italy"? For legal reasons perhaps?
Lastly, I had a chance to see the inside of the amp when the dealer was opened it up to display the 4 AAA rechargeable batteries. I'm not an electrical engineer, but honestly I was shocked to see how simple the PCB board was. It actually looked similar to the MK I version one
 
There you have it. 
 
I'm happy with my new amp. I didn't even have a chance to appreciate the XJ03 in depth. But a lost in confidence and for the reasons cited above, I have decided to move on. There are a lot of amps in that relatively high price range. I'm just relieved that this episode is over.

 

[tk3]

I'm surprised you bought this if you'd already seen the internals of the previous version.
But at least you were able to exchange it, and your experience is useful for those who may be considering a purchase, considering there are very few (valid) impressions out there.
 
I wonder how many people will buy this thing now, excepting sovkiller .