15/01/2020
Little Bear Tubes with V5i Op-amps - The TechnoGoob Review
Burson Audio Supreme Sound Op-amp V5i
https://www.bursonaudio.com/products/supreme-sound-opamp-v5i/
Little Bear B4-X Portable Dual-Mono Vacuum Tube Headphone Amplifier
https://www.amazon.com/Little-Bear-Dual-Mono-Headphone-Amplifier/dp/B07KJ18H75?ref_=ast_bbp_dp&th=1&psc=1
The Little Bear B4x portable tube amp is fairly well known for it's good "tubey" sound - and has become one of my favorite audio devices. I first learned of it on an airline flight for work - and have happily used it since. Recently I thought: What if it could be BETTER? For me personally that comes down to 2 specific options: I'd like to have it powered off "mains" while using it - either USB or even a dedicated AC Adapter. The battery/portability is handy, but can get annoying when I can't listen and charge at the same time, which occurs more often than I'd like.
The other thing I started thinking about was "tinkering" with the sound (Hacking/Modding, etc.) Unfortunately, the B4x (and B4 before it) don't allow you to "roll" tubes. Luckily, the op-amps are user-swappable! This seemed like an interesting opportunity to tinker AND evaluate the impact of an op-amp upgrade! After a little research and for a relatively inexpensive investment, I decided to try a set of Burson Audio V5i op-amps. Easy - I can replace a couple IC or two - So I did.
Installation
The Little Bear B4x has a very simple aluminum frame with 4 hex screws each on the top/bottom panels - and I've found it easiest to loosen all 8 screws a little, and then remove the 4 screws on the FRONT (the panel with the window). This saves the hassle of sliding out/in the battery/wires.
1. Place the B4x flat on it's "back" on a work surface - with the window facing up, and the volume k**b facing away from you.
2. Loosen all 8 hex screws.
3. Remove the 4 screws in the corners of the window panel (upper most corners).
4. Remove the front window panel.
5. Identify the two 5532 IC op-amps - on the b4x these are the ICs located in-board from the tubed, near the base of the tubes.
6. IMPORTANT: Note the orientation and pin-locator indicators!! (The notch in the chip and the dot printed on the chip - write it down or take a picture on your phone for safety!!)
7. Remove the IC op-amps with steady, even, upward pressure - preferably using a chip-puller - and set the chips aside.
8. Orient the Burson V5i op-amps based on the pin indicator dot or the IC notch which is visible underneath the V5i.
9. Insert the Burson V5i op-amps with steady, even (firm but soft) pressure until they seat fully.
10. Replace the front cover and screws - tighten ALL screws.
Test it!!
It takes about 15 minutes and is very low-risk. There is no soldering or technical challenge - just be careful, watch the orientation and enjoy the results.
Not a bad way to spend a few hours - focusing on listening to music…
Testing:
I own a B4 and a B4x. I am not able to tell the difference between them for "sound", so I'll swap between them using the same source->DAC and use the non-balanced cables for both headphones.
My source Files are all Flac Audio
My DAC: I'll use the Fibre-Optic input or iPhone-usb input into FIIO Q5, using line-out cable to B4/B4x, or direct headphone for baseline.
Headphones: Audeze iSine10 and Audeze LCD2 Classics. The headphones have different qualities, with the iSine sounding "smaller" and a little "brighter" given same input as the LCD2 Classics.
Note this is not a test of mono/balanced, so I'll only use non-balanced cables and inputs.
For fun, I added a Tascam Dr-40 and recorded the output from Q5, B4 and B4x (before and after the Burson swap). This allows for a graphical and audio comparison of the audio output, which was interesting, but not purely analytical/scientific?
How Does It Sound?
BETTER. I like it. A LOT.
Obviously, this is purely subjective based on my tastes: This upgrade nails a great balance between "CLEAN" presentation and "TUBEY" warmth.
The FIIO Q5 is my "clean" DAC/AMP baseline reference, and my Schiit Audio Bifrost/Valhalla2 stack is "warmer" but still precise (it leans towards more precise with a bit of "tubey"). The B4 (non V5i) holds down the far end of the spectrum with Lovely TUBEY Goodness.
The B4x/V5i upgrade fills a sweet spot of "detailed AND tubey". TUBEY-er than the Valhalla2 but more detailed than the non-V5i Little Bear. Take the Tubey goodness and throw the detail back in on top. I think that's probably backwards - as the tube is probably after the op-amp - but either way - using the b4/b4x with original 5532 op-amps is like using SLIGHTLY lower-res source files.
The Burson upgrade brings back guitar string squeak/scrape, voice detail and wind/breathe sounds giving definition to the music and vocals. The tube warmth/depth is still there.
Tracks that have wind-noise in the back lose the synth-feel and sound like wind. In general, note "attack" is sharper and more defined. Where the pre-upgrade B4 smoothes out the sounds a bit, the Burson V5i upgrade brings back the subtle variations in tone/detail mixed into the smoothness.
It's also interesting to me that the benefit/impact is song/track specific, and also genre/style has an impact. Highly electronic music, such as dance/techno/trance has less obvious difference between the two amps, while classic guitar and vocals have a much more enjoyable impact.
There is enough noticeable benefit for me to recommend this upgrade to anyone who has the b4/b4x. Where the non-V5i is WARM, TUBEY goodness - the B4x-V5i brings back the little details that are the reason we listen to HiRes Audio. I'd also suggest that if you're using a 5532 op-amp - check out the Burson v5i options and make the change.
