In March I picked up one of these little Bravo Audio V2 class A hybrid tube amps on sale. This neat little headphone amp uses a 12AU7 vacuum tube to provide that ‘warmth’. There are plenty of articles, reviews, and forum posts that go into the details of what this little amp is capable of, plus it’s moddable. I bought it because I love tube audio and I could have some fun and tweak it.
First Impressions
This amp looks like it was designed to be modded, but the reality is that the PCB is rather fragile. Traces are prone to falling off, especially if you use a soldering iron that is too hot. The first thing I had to do to mine was retin it with fresh high quality solder. It looked like it had been soldered with J-B Weld, plus it cleared up the audio. Once that was done I started swapping different 12AU7 tubes from my collection, eventually decided on an Electro-Harmonix for daily use. The stock tube didn’t sound bad, but the new EH 12AU7A seemed to handle the highs and lows better. I tested a vintage clear-top RCA, but the low ends sounded muddled, it is possible that the tube is failing. I proceeded to use the amp in this configuration at my job.
Time To Perform the Mods – Easy First
The most common mods are component upgrades. Replace the electrolytic capacitors with higher quality 35V caps. Interestingly enough, when I was replacing the caps, I saw that the circuit board states that these should be 35V. This is an easy mod, there are only three caps, 1 – 6800uF, 2 – 1000uF.
Final result with new power cap
Upgrade the MOSFETs – Hard Next
Replacing the IRF630Ns with almost any of the IRF510-530 series will improve the soundstage and roll-off. I opted to replace mine with the IRF530N, an improved version of the IRF510. This mod is not as easy as the heat sinks for the MOSFETs should be replaced with larger ones to handle the increased power consumption and thus heat generation. On my board I had to drill out the old heatsink mounts, and some of these mounts do go near traces. I do not have precision tools.
Work in progress on the amp
In progress fitting of the heatsinks
New IRL530N MOSFETs
The Final Results
I have been using the amp daily for the past week. It sounds so much better now, a noticeable improvement. I consider the amp and the mods a worthwhile improvement.
The final result