RSA * Dark Star * SE and balanced, dual chassis amp designed to drive most any HP . .

[El_Doug]

So......
 
For those who want the Dark Star to run within acceptable levels of THD+N, only those who will be running their HE-6 at a constant 120db should buy it. 
Therefore, assuming that an audiophile will not want to go deaf, those who buy the Dark Star are only planning on listening to music for 15 minutes daily (according to OSHA). 
 
$3,000 for 15 minutes / day... seems kind of steep to me
 
Quote:

From reading the datasheet of the OPA541, it's very clear the chip was chosen for power and not for its noise performance.  The OPA541 is noisier at low power than it is at higher power - at 100mW output the THD+N is 2% at 10 kHz, and 3% at 20kHz.  That doesn't seem ideal.  At 5W, however, THD+N remains below 1% in the audio band. The OPA541 appears to be happier when outputting a lot of power.  That's the purpose of this particular amp.  I don't see where it has been suggested that it be considered a "one size fits all" headphone amp. As such, it seems to me that on paper at least, this amp is going to be best used for its purpose of driving demanding headphones like the HE-6.  However, I have never believed in listening to paper. 

 

 

[Skylab]

Sorry, I should have been more clear - that was not outputting 5W into the 50 ohm load of the HE-6.
 
And again, just for clarity, the above was a discussion of the OPA541 only.  I have not, and unfortunately lack the proper equipment, to measure actual THD+N of the DarkStar itself.
But more than that, I still don't believe you can understand the sound of a whole amplifier by looking at the data sheet of the output device.

 

[jude]

 
Quote:

...Capacitor coupled SS amp that is quad mono so it drifts like mad and has to be extensively shielded so it doesn't pick up noise...

 
To the best of my knowledge, the Dark Star does not have a single capacitor in the signal path, from input to output.  Where are you seeing the coupling capacitors?

 

[daveDerek]

Quote:

To the best of my knowledge, the Dark Star does not have a single capacitor in the signal path, from input to output.  Where are you seeing the coupling capacitors?

Jude, spritzer was answering a question regarding what was under the hood of a Rudistor amp that he previously commented on, not the Dark Star.

 

[jude]

Quote:

Jude, spritzer was answering a question regarding what was under the hood of a Rudistor amp that he previously commented on, not the Dark Star.

Dave, thanks for the clarification.
 

 

[Syan25]

Still - can't get my head around spritzer's negativity towards Ray's amps. Doesn't sound objective to me...

 

[fdhfdy]

Quote:

Very approximately, 12" w x 9" D, and the whole stack is 7" high.

thats a right size as a desktop gear. thanks for the info. 

 

[Frank I]

WOW. Many ugly comments from people who never even heard this product. I think before any can really comment they need to spend some time with the product.  I cannot see how somebody can say its the worst amp ray ever made and then call is crap without listening to the product  is being irresponsible. This appears to be  personal and really confusing why it has been posted publicly.

 

[spritzer]

Saying that THD at 3% isn't ideal is a massive understatement to say the least.  Saying that this amp will run at 40W constantly is just wrong and Skylab should know better.  Most of the time this amp will output a fraction of that so the distortion will be high and lets not forget that this isn't a pure datasheet design so the measured performance could be far worse.  Ray's amps certainly have been known to have an appalling measured performance. 
 
With Tyll doing such a great job of measuring headphones why should be settle for subjective reviews alone?  Measurements aren't the only thing that should guide us but they are a crucial part of the chain. 
 

Still - can't get my head around spritzer's negativity towards Ray's amps. Doesn't sound objective to me...

Well Ray is as dishonest as they come (making his customers pay for his Paypal fees is just priceless) and the crap he tried to pull at CJ'10 just goes to show what kind of a character he really is.  That said I evaluate his products based on what I have in front of me but after being in the center of the whole Single Power mess I have zero tolerance for manufacturers pushing badly designed crap as "reference quality".  This doesn't just apply to Ray but he is certainly one of the worst offenders along with Rudistor.  Class B output stages or SRPP based amps which just barely function into one load are just the tip of the iceberg.  Dig deeper and you find shockingly bad power supply "design" and with the A-10, complete and utter lack of understanding on how you are supposed to handle tubes safely.  There he is in good company with Mikhail from Single Power...

 

[dminches]

From my perspective trashing someone publicly shows no class and makes your other statements lose all credibility.  And, to further trash a product made for listening without having listened to it is the icing on the cake.  Just my opinion, of course.
 

 

[Skylab]

Quote:

Saying that THD at 3% isn't ideal is a massive understatement to say the least.  Saying that this amp will run at 40W constantly is just wrong and Skylab should know better.  Most of the time this amp will output a fraction of that so the distortion will be high and lets not forget that this isn't a pure datasheet design so the measured performance could be far worse.  Ray's amps certainly have been known to have an appalling measured performance. 
 

 
I did NOT, ever, say "the amp will run at 40W constantly".  I simply said the THD+N of the OPA541 was better at higher power levels, which it is, and that with the HE-6, the DarkStar will be running at higher power levels typically than with less sensitive headphones.  This was in context of my being asked to try it with more sensitive headphones, which I indicated I thought was not a good idea. 
 
The OPA541 doesn't have a good looking THD+N curve.  I agree.  I said that.  But an amp isn't just it's output device, and one does not listen to the sound of datasheets.  That is all I said.  I'm keeping an open mind, and I am not deciding on the sound of a finished amp, which is the sum or its parts and its design, by looking just at the op-amps data-sheet. 

 

[sachu]

Rob, just curious if the request to review an amp was sent by you or you were contacted by the manufacturer. 

 

[Skylab]

Quote:

Rob, just curious if the request to review an amp was sent by you or you were contacted by the manufacturer. 

In this particular case, I made the request.  It looked like an interesting amp, I am a big fan of the new-gen planar/orthos, and I thought I would check it out.
 
In general, I would guess about half of the stuff I review is at my request, and about half is at the request of the maker.  Or maybe more like 40/60, as in quite a few instances my request for a review loaner is not accommodated.

 

[Duggeh]

Quote:

From my perspective trashing someone publicly shows no class and makes your other statements lose all credibility.  And, to further trash a product made for listening without having listened to it is the icing on the cake.  Just my opinion, of course.
 

 
[Duggeh emerges from the cobwebs]
 
 
If one denies the free forum which permits people to voice criticism openly nobody would ever know anything bad about anything and everything would be the best everything since everything.
 
The problem with the criticism of design that comes from those here who are able to articulate based on gained knowledge is that they have something in that knowledge which is as inaccessable to the lay reader as to be akin to sourcery. Ergo, when presented with information from such a person the reaction is to frame an analytical response along lines which call for clarification any issues the respondant does not understand (individual terminology for example). However, critical response to that same information is made in terms which the respondant is capable of understanding without further education, as such, we have the "you cannot say anything unless you have heard it yourself" line.
 
This is a line which since head-fi days of yore has been trotted out by those who never practise it themselves. Every day on this forum the same people regurgitate recommendations based upon what they have read from other people about headphones and amps.
 
"The HE90 is the best headphone, or the R10"
 
You can't say that until you've heard it yourself, how can you say that, you're just a fanboy, et cetera.
 
A double standard.
 
 
If you have doubts about the post made based on technological know-how, question the information presented. Don't engage in Ad-Hominum attacks.

 

[kevin gilmore]

So back in 2004 i designed the dynahi power supply with the opa541. At the time i also
built up one as an amplifier, and at the time listened to it with various headphones and
came to the conclusion that it sounded just like what i would expect from a device
with the THD graphs specified in the datasheet.
 
So i revisited this spent 2 days to get it right, took two of these, rewired for dual mono with dual mono power supplies,
balanced (balanced only) gain of 11, same exact resistor values ray used except that
i don't have the .5 ohm resistors in stock, so i left in the ultra expensive caddok .2 ohm resistors.
With the same value +/-40 volt power supply
 
this is before the modifications.
http://gilmore.chem.northwestern.edu/darkstarclone.jpg
 
And i sat down and listened to the thing with LCD2's because i don't own he6's. And i listened
to hd800's and a couple of different grado's. My opinion has not changed, this is a lousy and
noisy amplifier.
 
So i've now heard a virtually identical clone, and i'm not at all impressed.
 
Just for chuckles i took my krell fpb600 and hooked it to the lcd2's (with inline fuses just in case)
It sounds WAY better, and is far less noisy. And this is a 600 WPC (about 50 of which is pure class A)
amplifier.
 
For balanced use there are new national semiconductor chips with 2 matched amplifiers designed
for balanced output use, with way lower distortion. I've ordered a couple just to see how they sound.
 
Matching a pair of opa541's for balanced use to eliminate much of the 2nd and 3rd order harmonic
distortions is probably impossible due to thermal differences, and the quasi complementary output
transistors.
 
My dream amp for LCD2's, and likely he6's is still one of the nelson pass amplifiers. A perfectly matched
pair with a very black and silent noise floor. Or a dynahi,dynafet,B22