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RSA SR71b, quad mono balanced. img. 1 & 17 Review pg 32, 34, 68, UPDATED 4/2013 for Improved sound.

post #1 of 1192
Thread Starter 

with balanced input and output or single in and single out or single in and balanced out! It has a 26 plus voltage swing in balanced, 12 to 14 volts in single ended and plenty of power. The size is the same height as the Protector, a 1/2 shorter than the 71a and as wide. The measurements are 3.25” in length, .7” in height & 2.25” in width. A custom designed Alps pot is implemented for the volume control with the volume control knob being custom machined. 

 

 

DSC_7184sm.jpg

 

 

 

 

THE Blackbird SR-71B   a review:

 

How complicated can a review be? When talking or writing about sound, I am finding that with all of our interpretations of what we hear, what we like to hear, what we need to hear and what we should hear to sometimes be at opposing ends of this art. Since we are interpreting sound, music, which to me is art, the instrument to do this, by design must malign this art as little as possible if we are to remain true to this record of an event.

 

The Blackbird SR-71B is a link in the chain the conducts an electrical signal to transducers that turn this into energy into sound waves. Since the 71B is an amp with balanced and single ended drive capabilities, your choice of how you wish to listen is doubled.

 

The source is from lossless files on my iRiver via optical out or my MacBook Pro using either optical or USB in 24/96. The optical cable is the Sys Concepts 1300 fiber toslink that has proved to me that there is more to be found on this music and that the signal can be lost in conventional optical cables. The IC from dacs, the MB-1 dual dac, Boomslang balanced dac or a dac for USB 24/96 is the Twag for balanced and my own silver IC for single ended. Much of the listening was done with the Audez’e LCD-2 as I feel this is the most resolving phone I have heard and gives me immediate feedback and while not clinical, can dissect what I am hearing to a point I know what everything up stream is doing or not doing.

 

The monitors used are all balanced. The JH13 Pro with Twag, HD650, Ultrasone Ed. 9, ESW 10, Grado HF2, PortaPro, LCD-2. Again all are balanced and can be used single ended with my adapter.

 

The music used is lossless 16/48 and 24/96. Types of music pretty much covers the map from classical, jazz, rock, rhythm and blues, reggae, trance, metal and what ever else falls onto my ears. I would like to stress again that using the new 1300 fiber toslink cable with it much wider bandwidth and lower modal dispersion, allows even the 16/48 to sound better let alone what it does for 24/96 since most toslink can barely do better than 16/48 and often it will not even resolve that.

 

General characteristics of the SR-71B:

 

What comes to mind when I think of the sound that comes out of the 71B is not only that it resolves the body of the main instruments and voices, but also that of what I would call secondary sounds. Like a story you have the protagonist and the antagonist and then there are the foils, the characters that also build the story, give it texture and if the story is well written, the depth of a believable event but are never developed like the main characters. The 71b resolves the secondary sounds giving them body and substance more than a foil, which doesn’t have the full dimension of persona built upon. With the 71b you can hear more deeply into the recording, which in turn brings more life and realism to the auditory imagery laid out before you.

 

I don’t know what the noise floor is for the 71b but it must be very low. The notes rise and fall with a decay that fades into blackness giving them a distinct quality.

 

Side note:

 

As I write this electricity has gone out. The island of Pohnpei has one power plant that runs on diesel generators and one of the two has been down. That puts all the strain on one and we often lose power for anywhere from 10 minutes to hours. That second generator is now down. I have been listening with my MacBook Pro with an external hard drive with 2300 albums during this particular writing so with a pull of the optical cable and switching to the iRiver it is just a blip. On I go with high quality balanced sound via battery.

 

Audible frequency response:

 

   The upper frequency response of the 71B is smooth and extended. By extended there is no audible rounding of the high frequency range but a natural extension that lacks any grain or artificial edge. There is an airiness to the sound when a recording has this.

 

   Mid frequencies are full and have a slightly warm tone that is very analogue like. I do not find the mid frequencies are pushed forward nor are they recessed. The human voice, male or female, is portrayed with a fullness that imparts a feeling that it comes from a body. There is a mental image of human rather than sound coming out of type of void.

 

   Low frequencies are extremely well controlled and it is easy to follow even on bass heavy recordings if the recording is well done. This amp will not correct poor bass but does portray well recorded bass, as it should be, with bass notes that do not blur one into the other.

 

On instruments my comments on the frequency range follow suit. Well recorded acoustical guitars can be beguiling. There is such a melodic tone that if you are listening and doing something else, it is easy to be drawn back to the music and forget what you are focused on. Electric guitar, sax and instruments with drive have the right bite and edge. Piano has the nuances and volume, that come across with ease giving this instrument the respect it deserves.

 

Further observations:

 

The only way that background sounds could have substance is if the amp is transparent enough to resolve this and that is what the 71B does. By being transparent and handling the macro and micro dynamics and detail, sounds do not bump into each other but are presented as part of the whole but also as distinct parts within the soundscape.

 

The balanced output on this amp does differ a little from the single ended. In single ended you are put slightly further from the music, which for me is a nice exchange. You still have an amp with solid bass, great transparency and a soundstage that has believable width and depth but a little different perspective. Rather than sounding like the balanced section but having a decrease in sound quality, the single ended output is a slightly different placement while maintaining a high quality to the sound. As in a change from perspective there is a small change in tonality, which if understood you are a little closer with the balanced mode can be understood. To have the choice of either is excellent in my opinion. For the very hard to drive headphones the balanced mode does also offer the doubling of power and with this, you still have a truly portable, not transportable, headphone amplifier. 

 

Summary:

 

So that is my basic synopsis of the SR-71B. The balanced section is a little different presentation, as the drivers are driven both with the positive and negative current flow with 26 volts of voltage swing while the single ended is just that, a positive current flow to ground and approximately 13 volts. In a small package you get a beautifully crafted and looking amp with excellent sound that further helps us to interpret this sound, this art, we call music.

 

Features: 

 

   A custom volume control with R and L balance control.

   Three gain positions.

   Balanced and single ended for both input and output.

   More than a 26 volt swing in balanced mode and 12-14 volts output in single ended. 

   Internal custom battery with external charger/AC-DC converter.

   A 3 year warranty on the battery and lifetime warranty on the amplifier. 

   Size: 3.24 inches in length, .7 in height and 2.25 inches in width. 

   RSA reliability and support. 


Edited by jamato8 - 2/3/11 at 4:00pm
post #2 of 1192

Interesting indeed!

post #3 of 1192

Any guess on the release date and estimated price?

post #4 of 1192

TEN opamps!? 

 

post #5 of 1192

And it just NEVER stops! :)

 

post #6 of 1192

That should take care of all the high impedance cans.

post #7 of 1192
Quote:
Originally Posted by wuwhere View Post



That should take care of all the high impedance cans.



There's a difference between sensitivity and impedance. Impedance, by itself, tells you almost nothing about how hard headphones are to drive. Headphone impedance is only relevant when considered with the output impedance of the amp, and that mostly tells you how well the power transfers. You also need to know the output power of the amp and the sensitivity of the headphones to figure out how well the amp will drive the headphones.

Not to thread jack - congrats, Ray, and I hope you do well with the new amp!
Edited by Uncle Erik - 7/17/10 at 6:45pm
post #8 of 1192


 

Quote:
Originally Posted by Uncle Erik View Post





There's a difference between sensitivity and impedance. Impedance, by itself, tells you almost nothing about how hard headphones are to drive. Headphone impedance is only relevant when considered with the output impedance of the amp, and that mostly tells you how well the power transfers. You also need to know the output power of the amp and the sensitivity of the headphones to figure out how well the amp will drive the headphones.

Not to thread jack - congrats, Ray, and I hope you do well with the new amp!


Agreed about sensitivity, even impedance. Usually manufacturers, specify their cans' nominal impedance but we know that impedance varies with frequency. And the amp has to supply that voltage across the frequency response of the can.


Edited by wuwhere - 7/17/10 at 7:09pm
post #9 of 1192

picture?

 

 

I want to see evidence.   :)

post #10 of 1192

Aaah, nice! :D
 

post #11 of 1192
If it is a quad mono, I think B58 is the appropriate name :)
post #12 of 1192

All this portable balanced gear coming out is doing my head in... Argh! Im trying to be budget orientated! This stuff doesnt help!


Edited by Townyj - 7/18/10 at 6:19am
post #13 of 1192

 

Should I get it or stay with Protector ?  

post #14 of 1192

 

Quote:
Originally Posted by Audio-Omega View Post
Should I get it or stay with Protector ?  


Get it, then compare and keep the one you like the most. Or?
 

post #15 of 1192

 

The website says it will stand toe to toe with the best balanced home amps out there, that's good to know.  However I hope its price won't.  

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Head-Fi.org › Forums › Equipment Forums › Portable Headphone Amps › RSA SR71b, quad mono balanced. img. 1 & 17 Review pg 32, 34, 68, UPDATED 4/2013 for Improved sound.