Bravo V2 - Review, Tube Rolling, Mods (coming soon)
Jul 9, 2013 at 8:27 AM Thread Starter Post #1 of 61


100+ Head-Fier
Jun 24, 2013
Bravo V2 Review
So this is my first foray into the "hi fi" world. I buddy let me listen to his HD650's on his Little Dot MKIII and I was hooked enough to get into the action. So I did some looking on this site and others as well as the r/headphones. 
I purchased a set of Monoprice 8323 for listening. I had a set of $20 over ear JVC's, but just switching to Mono's was a significant change. All the test were conducted using a stock (no board changes) Bravo V2, Monoprice 8323, FLAC files on MOBO output using MediaMonkey with no equalization enabled. Each tube was given a minute to warm up, and was bought under the pretense that it was tested and good. Being a EE I immediatly went past the ohh and ahhs of tubes and decided to try my hand at rolling. Considering I won the V2 for $51 shipped I spent some cash and ended up with 30+ 12AU7/A/WA tubes from various manufacturers in various states. The purpose of this thread is to give a noobs perspective on the different tubes I tried and how they sounded. After I get done reviewing these tubes, I will probably dump the ones I dont like back on ebay.
So here is the playlist:
-Queensryche - The Mission
-Queensryche - Spreading the Disease
-Alkaline Trio - I Wanna be a Warhol
-Alkaline Trio - She Lied to the FBI
-Kendrick Lamar - m.A.A.d city
-Kendrick Lamar - good kid
-Daft Punk - Get Lucky
-Daft Punk - Instant Crush
The playlist was chosen to run the spectrum of both audio and music + they are some of my current fav's. I compared the stock tube to direct input, and then compared the rest of the tubes to the stocker. I will also add pictoral DIY's to this thread later on the various mods. 
A few upfront apologies:
1. I am an audio noob, I build/race cars and motorcycles so I doubt I have the sharpest hearing ever. 
2. English is my second language. I handle it pretty well, but mistakes do happen.
Tube Pics:





Stock China 12AU7 Tube:

Right out of the box the Bravo sounds pretty good compared to direct input. It has no issue blowing out eardrums and speakers. At a reasonable volume it offers a lot of clarity. Not particularly heavy on the bass but in the QR songs especially you notice little sound effects and stuff that is in the background. I have listened to these songs many times over the years and am only now hearing bits and pieces I have never heard. With AT it seemed his voice and other mids drowned out everything else. The drum was weaker than direct connection, and those high hats they love ohh so much could be a bit tinny and unpleasant at times. This is especially obvious on the chorus of track 4, there is a point where its just vocals and the bass drum. On the K. Lamar tracks that are bass heavy, it 808 is obvious but its somehow not convincing. Daft Punk sounded really flat, especially get lucky. In fact I was really surprised and dissappointed. The vocals were flat, the bass was flat, and that little guitar strum sounded very heavy hearted. 
Daystrom Nimchimen 12AU7:

And the bass is back. And back in a big way. I noticed a night and day difference between the Alkaline trio songs - I could hear the feel the baseline in the chorus, the highs were nice and crisp, and the mids were well balanced. Since I bought all the tubes in one big lot I do not know the dollar value on this bad boy but its a keeper. I have 5 of them, and I will defintly keep at least 2 of them. To really notice the difference between this and the stock china unit you just need to listen to the first 25 seconds or so of m.A.A.d city. There is a heavy bassline and some high pitched noises and you can hear them. You can almost feel them laying on top of each other if that makes sense. I was excited as I moved to the DP songs. Again listen to the first 20 seconds or so of Get Lucky and you will never go back to the stock amp. At the end of the first line of the song he gives a low "ughh", it was almost undetectable with the china tube, but there it is nice and clear. Honestly I was grooving in my chair typing this as I was listening. The chorus of Instant Crush is glorious, even though the piano/synth is close to his voice in pitch you can hear it all very clearly, the highs of his voice being above the synth. 
RCA "Red Lettering + Clear Top + White Plates" 12AU7:
Hrrmmm. I was led to believe the RCA clear tops were quite nice. I am  not sure if this is the one people refer to, but it looks rather similar to some of the online pics, so I am going to assume it is. While it is not as bad as the original china tube its not a whole lot better. We are back in the land of the flat. It gets points for better low end compared to the china unit. The QR songs sounded ok, but were slightly lagging the the Daystrom. The AT songs were way lacking. Definitly still better bass and soundstage than the stocker but pretty meh compared to the Daystrom. I feel like overall this unit is better on the low end and maybe slightly better on the hi's than the stock unit, but its really lacking in the top end. Instant crush was particularly flat, his voice basically smoothes into the chorus if that makes sense. There is a clear lack of resolution. 
RCA "Gray Lettering + Mirror top + Gray Plates" 12AU7:

ahhhhhhhh. This one is super boomy. Quite frankly its even worse than the red clear top. This is really the only way to describe it, it even made Daft Punk sound boomy, like I was listening inside an empty metal building. I ended up trying a second one I had of the same type but it sounded exactly the same. I ended up skipping past most ofthe AT songs cause I couldn't handle the sound. Quite frankly this one annoyed the **** out of me. I dont think I really finished any ofthe 8 songs. 
Sherwood Mullard 12AU7A:

This one takes a while to warm up. It didnt really come alive until the second song (about 5 minutes of run time + 1 minute of pure warm up). However once it came alive it was quite nice. Actually I would say this was eqaul or better than the Daystrom. This was a little more heavy on the low end, and a little less on the hi's but thats not necessarily a bad thing. Excellent clarity, excellent soundstage. In the later parts of the Get Lucky when the other guys sings in the back ground with the animatron voice you can clearly distinguish it from the chorus, perhaps even better than the Daystrom. Both Daft Punk songs were absolutly a joy to listen to with this tube. Bottom line is I will hang onto this one as well. 
General Electric 12AU7WA (mil spec) / General Electric 12AU7A:

First thing first. These two sound exactly the same. Perhaps sharper ears are needed to tell the difference, but whatevs. A little flat compared to the Mullard and the Daystrom, but still light years ahead of the stock unit or the RCA tubes. Even daft punk sounds pretty good. A quick search of ebay shows these bad boys can be had for $9-11 shipped any day of the week, if money is your main concern get this tube and leave it be. 
Sylvania "Green" 6189 / Sylvania "Yellow" 12AU7A:

The queensryche tracks were a little flat. With Alkaline the bass line was a little low, but the vocals and hi's were nice and clear. Its hard to quantify but if The Daystrom and the Mullard are 10/10, and the GE tubes are maybe 7.7/10, this one is like a 7.0/10. Its not bad, and way ahead of the stocker. But having listened to those other tubes first I was definitly spoiled. If I had jumped straight to this one from the stock unit I would have been more impressed. The bass on Kendrick's tracks was not as strong as with the others, and someof the smaller details of the background track was lost. This lack of clarity, or resolution, or whatever you want to call it, is really obvious in the daft punk tracks. The yellow sounded better than the green but not drastically. Enought to notice but it doesnt really change its ranking.
International Service Master 12AU7A:

This unit is apparently NOS, and made in germany.  Sweet. This one ranks right up there with the Mullard and the Daystrom. Its a great sounding tube. It a little "warmer" than the rest, everything sounds happier and brighter. The bass is more melodious, good soundstage, just nice. Well balanced. I did not write too much here because I was too busy listeing to the music. 
Raytheon 12AU7A:

Also a NOS piece, made in Japan. However thats where the comparison to the internation ends. This one is boomy, better than the RCA grey but not by much. Good clarity but no wow factor. Boomy. Meh. 
Hewlett Packard by Memrex 12AU7:

This one looked pretty old and beat, but it delivered a suprisingly melodic sound. Not quite as sweet as the International and not quite as clear as the Daystrom. A good in between, I wouldnt choose it over either of the two, but depending on cost and availability its a great little tube. Alkaline Trio sounded pretty good on this bad boy, so did Kendrick Lamar. Honestly there are not real negatives I can add other than there is a bit of a loss of details, things are not as clear as they are with other tubes. Very solid bass line on the rap tracks. Daft Punk wasnt quite as clear and melodic as others. I guess this one gets left on the roadside as well, just maybe not choking quite so much on dust. 
"Flying M":

Hopefully someone can chim in on the brand of this tube? It would be cool to know cause this is another great sounding tube. A+ Marks for clarity, highs and mids. Low end could be a bit better but its very clear. You can hear all the various differences. Quite honestly if you could only have one it would be a close call between this one and the Daystrom. Even Daft Punk sounded groovy. For those two songs the International is hands down the best sound but this guy did quite well for himself. Excellent clarity, mids and hi's. Do Want. 

Again maybe someone can ID the actual maker? Cause its another good one. Very clear hi's, good detail, nice sounds stage. Another keeper. 
I also have another 10 units I can not ID with anything, so I wont bother with them. If you need any of these tubes let me know cause I have multiple copies of a lot of them. In conclusion the all around winner is the Daystrom, with the Mullard coming in a close second. For a different warmer sound turn to the International Service Master. I am looking forward to doing some mods and getting an even better sound out of this guy, and I will keep you guys updated. 
Jul 9, 2013 at 1:25 PM Post #2 of 61


Headphoneus Supremus
Sep 29, 2011
Very well done comparisons.  Nice pictures as well. Excellent job on this thread!

Jul 13, 2013 at 9:18 PM Post #4 of 61


100+ Head-Fier
Jun 24, 2013
-Bravo V2 Amp w/ International 12AU7 Tube
-Grado SR-80
-FLAC Files played from MediaMonkey output via MOBO audio jacks.

-Swap the IRF630 to IRL510s, Swap in the LM317A fets. Leave the rest alone....

What: Crosstalk Reduction Mod

Why: Crosstalk is basically unwanted noise in the circuit around the tube. We are getting rid of it.

How: Simply cut where its marked in red (make sure its above the resistor or you will lose a channel). Solder a small wire. Cross talk gone.

Is it better: Noise at full amp with nothing playing is reduced. Hardly noticable when playing. I have not had any serious issues, and now I never will.

What: Swap IRF630 for IRL510/530

Why: Increase highs, reduces distortion. Extends the frequency range.

How: Simply replace the IRF630's (2) on the board with IRL510 or IRL530. Remeber to buy a thermal compound like arctic silver or similar. These are the two FET's with the larger black heatsins.
-Unsolder the heat sinks first.
-Remove the screw and pull out the heatsinks.
-Heat up and pull out the fets, then heat up each hole and blow in it sharply to blow it clean.
-Reassemble the FET/heatsink then put it in the board and solder it back.

Is it better:
Wow. I put on Daft Punk's Lose Yourself to Dance. Wow. Wow. Wow. The highs are much clearer, brighter, and sharper. This is the mod to do first and fore most. Only downside is the LM317's are going to get much hotter. This is the reason for the next mod.

What: Swap LM317 to LM317A

Why: Due to our change to the IRL510 we are now sending more power through the stock LM317's. The "A" Part is a higher Q part, built to higher specs.

How: Similar to the last mod. Pull the FETs/heatsink. New thermal conductive paste. Solder back in.

Is it better: I did not notice any specific sonic change. The higher quality part is only a few bucks and can handle the increased heat.

What:Getting rid of the Pop noise

Why: Its annoying and could theoretically (if loud enough) damage the headphones.

How: Replace the circled resistor with a 10Kohm unit. Place a 10V 100uF cap across the red LED

Is it better: The popping noise when you turn it on and if is significantly reduced.

What: Change output caps to Nichicon 2200uF 35V

Why: Changing the two output coupling caps should help give some headroom.

How: Change out the two brown output caps with the new units

Is it better: I cant say that I noticed a significant sonic difference. Plus now I will have to drill extra holes in the top plexy to fully assemble it back again.
Jul 18, 2013 at 5:35 AM Post #5 of 61


1000+ Head-Fier
Apr 26, 2013
So Cal
FWIW, I thought I would add this data to your Bravo tube rolling thread.
So I've been flipping my setups around just to play with things. I'm the curious sort I guess. I decided to tinker with this Pure i-20 a bit more, and it's probably been too long for me to return it. Anyway... the "normal" setups I have for home and work go something like this:

Work: iPod -> (Pure i-20 DAC) -> Bravo V2 -> Sony MDR 7506

Home: Laptop -> Schiit Modi -> Schiit Magni -> Beyerdynamic DT770/250

The setups sound different, but both sound good. The Pure i-20 is the newest addition; it is BRIGHT. Maybe even harsh. I am finding out I can't turn the volume up a lot, or I need to take it out of line and run the iPod directly into the Bravo. Aside from the brightness, it is bringing some unexpected clarity to what I keep calling my "cheap" work setup. Anyway, so I decided to do some tube rolling, and switch this around. Since I can't tube roll at work, I brought the Bravo home and changed the home setup to this:

Home: Laptop -> Schiit Modi -> Bravo V2 -> Beyerdynamic DT770/250

The bottom end on the Beyers went away with this setup. That was a little surprising, given how much headroom the Bravo's volume knob usually has. I presume this was an impedance thing, so I switched out the headphones to the work cans:

Home: Laptop -> Schiit Modi -> Bravo V2 -> Sony MDR 7506

This brought the bottom end back. I was also a little shocked that the Sony's were sounding better than the Beyers on this setup. The MDR 7506's have an impedance of 63 ohms, which seems to work a lot better than the 250-ohm Beyers (and I'm now also kind of curious how 32 ohm cans would sound, but I digress).

So now that I had my tube rolling setup determined, I started a-rollin'. And a rollin, lol. I'm sure someone will laugh at me for blowing a pile of money on 12AU7 tubes to roll a Bravo V2, but there you go. As I mentioned earlier in another post, my family life has been going whacky for the last month or so, so I guess I really needed a distraction from the grief. Besides, it keeps me off the streets and out of trouble. But I digress again. I'll discuss the tubes in a moment.

So because I didn't want to keep carting around my tube rolling setup, I decided to take the other parts to work. So my work setup temporarily turned into this:

Work: iPod -> Schiit Magni -> Beyerdynamic DT770/250

Now, this was a real shocker: the Beyerdynamic cans sounded just as bad as when I was trying to drive them with the Bravo V2. For some reason, the Magni was no longer driving them properly. Ok, the Magni was being driven by an iPod, but can the DAC in an iPod really be that bad? I guess it is. I did not try the Pure i-20 on this setup. I suppose I should have, but I had it parked and out of the way for the moment. Someday curiosity may get the best of me, but I didn't go there for now. Suffice it to say that for a few moments, I resurrected my Sony MDR NC-40's and ran them with the iPod. Then I remembered why that was a bad idea. So this work setup didn't last long. I briefly flirted with the idea of buying another set of cans. Bleh, not now. Spent too much on tubes for now.

So back to the tubes. My music selection is probably smaller than others. But I have some nice selections, and I decided on a selection of tunes that I am now calling my Test Music. The primary selections from the library I use the most (song names eliminated for space):

- Apple Lossless -
Andreas Vollenweider: Book of Roses
Pat Metheney: One Quiet Night
Peter Gabriel: So
- Apple 256 Kbps AAC -
Korn: Untouchables
Led Zeppelin: Celebration Day (Live At O2 Arena, London)
Lindsey Stirling: Lindsey Stirling
Seether: Finding Beauty In Negative Spaces
Seether: Holding Onto Strings Better Left to Fray

The 12AU7 tubes I've tried:

GE 5 star 5963 (mil spec 12AU7)
Telefunken x 2 (long grey plate)
Tung Sol x 2 (long grey plate)
Westinghouse clear top (long grey plate)
Westinghouse yellow label (long grey plate)
IEC Mullard (I think this was a short grey plate)
Amperex Mullard (long grey plate)
Conn rebranded, not sure what the original is (long black plate)
Sylvania green label (mid size grey plate)
Sylvania yellow label (long grey plate)
GE white label (short grey plate)
Olympio tv tube (long grey plate)
Baldwin organ tube (rebranded Sylvania, long grey plate)
JJ Electronics new, not NOS, from (short grey plate)
Electro harmonix new, not NOS (short grey plate)
...and of course the original chinese tube
(and I still have a few more to test including a couple of the better Mullards)

I'm not going to torture you with a blow by blow description. I think it's probably more important to point out the lessons learned:

1) Unless you need a distraction like I did, it's probably not worth spending this much money to tube roll a Bravo V2.
2) The newly made tubes from JJ Electronics, Electro Harmonix, and the stock chinese tubes really do suck. Not by a whole lot, but it is a noticeable difference. I would sooner throw them in the trash then listen to them. I would only use them if they were the last tubes on Earth.
3) Long grey plates sound better than the short grey plates. Brand doesn't matter.
4) Black plates of any length, seem to sound as good as the long grey plates. Brand doesn't matter.
5) Sometimes people sell tubes on eBay because they are worn out. The first Tung sol tube I bought that really got me going on this, had a background hum that has never gone away. I am now assuming this is because the tube is worn out or defective in some manner, and the jerk who sold it to me on eBay really should have thrown the damn thing away. Instead, he made $12 bucks and screwed me. The second Tung Sol tube I tried did not exhibit any hum. I've heard a little hum from one or two of these tubes, but nothing too bad.
6) Telefunken tubes really are nicely balanced and pretty sounding, especially with music like Andreas Vollenweider. Even on a Bravo V2. But I find that I actually prefer other tubes, unless I'm listening to a particular type of music. Don't spend the money on them unless you really know you need to, or you get a good deal.
7) Newer Mullards like the IEC Mullard I tried, aren't worth spending a bunch of money on. Don't bother.
8) Tubes newer than the 1960's should be avoided if at all possible.
9) Rebranded tubes sometimes sound pretty good, but sometimes they don't. Examples: The Conn tube sounds pretty damn nice, but the Baldwin/Sylvania is leaning more towards the quality of the new JJ electronics crap. Don't spend a ton of money on rebranded tubes.
10) The mil spec 5963 tubes sound damn nice with gritty rock and roll like Seether. I'm really liking the GE 5-star 5963 tubes I found (got a pair for cheap).

So for now things are back to where they started, and I'm back to using the Pure i-20 at work. It is bright, but it brings a certain quality to the music stored on the iPod that I am finding that I like. I just have to remember not to crank it up very high. The side effect of this is that when I get home, my Magni+Modi stack on my Beyer cans sounds a little flat. Not tubey at all. I am now kind of disappointed in this development. I am also wondering if I'm just turning into a tube guy, and maybe I need to get a Valhalla+Bifrost for home instead, LOL.

I guess once you roll tubes, you don't go back?

Oct 15, 2013 at 8:15 PM Post #11 of 61


New Head-Fier
Oct 6, 2013
What: Swap LM317 to LM317A

Why: Due to our change to the IRL510 we are now sending more power through the stock LM317's. The "A" Part is a higher Q part, built to higher specs.

How: Similar to the last mod. Pull the FETs/heatsink. New thermal conductive paste. Solder back in.

Is it better: I did not notice any specific sonic change. The higher quality part is only a few bucks and can handle the increased heat.

Sorry for my ignorance but I was wondering if the FETs were the silver heatsinks? I found a diagram here but I just wanted to be sure. Sorry for the bother and thank for your help! :)
Dec 31, 2013 at 7:56 PM Post #13 of 61


100+ Head-Fier
Dec 4, 2012
   Excellent write up! I had the same experiences with my mods, fets made all the difference. This amp got me started in tube sound and indeed there is no going back for me. My bravo hasn't been used in over a year but I can't bring myself to part with it :)
May 27, 2014 at 3:57 AM Post #14 of 61


1000+ Head-Fier
Apr 26, 2013
So Cal
At long last, this weekend I had some time to start on modding one of my Bravo V2 amps. Some pics and notes to follow (please see notes at the end)...
Here's a shot after removing the IRF630's, the LM317's, and the input+output capacitors...

The first component removed was one of the IRF630's. I have a decent Ungar 42 watt soldering iron that I've had for years. I read that some people had difficulty de-soldering components due to the lead-free solder used on the original. I had the same issues. I probably damaged one of the reverse-side circuit traces on this component for this reason. Note in this picture that solder extends to both sides of the circuit board, which just makes things that much more fun...

So after the first attempt, I went back online to read some more. I found a couple posts that gave me the best suggestion yet: before attempting to remove anything, re-flow the original solder joint using leaded solder. After doing this, I had a much easier time removing solder from the leads. However, I still had to improvise, which I will detail further below.
In the case of the LM317 below, I had to actually remove the heat sink, in order to get to the leads of the device (so I could cut them). The reason for this will be detailed at the end of this post.

A bottom view of the circuit board after removing several components. If you zoom in you can see the damage to the circuit trace on the upper left solder connection.

So here I want to summarize several important lessons learned, for anyone else who is going to attempt these mods to their Bravo:
  • Assuming you're not rich and don't have a vacuum de-soldering iron, you must use a solder sucker. I did not want to attempt this without one. It was not an expense I welcomed, but after having attempted this, I can't say I'd have wanted to only use solder wick.
  • Have some leaded rosin-core solder, solder wick, a solder sucker, a quality 40 watt soldering gun, a magnifying glass, and a bright light handy. Those little helping hands widgets come in handy but they don't anchor things terribly well. I suggest making use of the assistance of a teenage child instead. Or a friendly neighbor, whom you tempt with beer.
  • Buy a small roll of 22 gauge copper wire for reassembly (use for the crosstalk mod, and to patch any circuit traces destroyed during de-soldering).
  • Use your 22 gauge wire during de-soldering - use it to clear out the circuit board holes after removing components. Poke it through, heating if needed, to remove any remaining solder in the hole.
  • Do Not Force Anything. That includes things like, not yanking solder wick off of circuit traces after the solder hardens. Re-flow the solder and pull it off while hot, to avoid damaging anything. The circuit traces on this board are fragile as hell.
  • Absolutely positively re-flow all solder joints, using rosin-core leaded solder, on the back side of the board, prior to attempting solder sucking or the use of solder wick. You may also want to re-flow on the front side, after cutting the leads off the chips.
  • Removing the chips: Don't try to heat up all 3 leads and pull the whole thing out at once. It won't work. Well, maybe you can, but I could not manage it. I ended up cutting the leads (using a small pair of dikes), so that just the leads were sticking up on the component side, prior to trying to remove them. I found it much easier to remove them one at a time. One of the LM317's required the removal of the heat sink in order to get to the leads to cut them (see pic above).
  • Removing the capacitors: Best done by heating up one lead at a time, and pulling the component from the other side. You can rock it out that way after 2 or 3 tries.
  • Please note that solder will flow through the hole in the circuit board, and it will exist on the other side (where your gun cannot reach it). You can mitigate some of this with the solder sucker, but not all of it.
  • You do not want to use a huge soldering gun (over 50 watts) - the higher heat will just peel the circuit traces off the board, which will make re-assembling this contraption more difficult. My ancient Ungar 42w gun was just fine.
  • I have not cleaned the rosin off the board yet. I did not use extra rosin (some recommend this), but the rosin from the re-flowed solder did get littered about the board. I intend to clean that up with alcohol prior to re-assembly.
  • Yes, you do need to count the cost of the supplies you buy for this as part of the cost of the amplifier. This thought re-occurred to me several times as I was monkeying around with this thing. Unless you're the type that already has this stuff laying around (I had some but not all of the gear), you're going to drop a surprising amount of money just for electronic equipment.
Finally, I should mention that one should not attempt this exercise unless you're willing to lose the whole amplifier. It became clear to me that I might not figure out how to pull these parts before destroying something, that I could not repair. I was glad I stopped in the middle, to find the hint about re-flowing the solder. That made all the difference.
And, please, don't ask me to modify yours LOL. After going through this, I can really see why nobody wants to do this for anyone else.
Aug 12, 2014 at 10:53 PM Post #15 of 61


New Head-Fier
Aug 12, 2014
So my recent mod was all about changing the looks of the V2 a bit.  I really did not like the looks of the plexiglass acrylic upper and lower cap.  I purchased some 1/8 inch african mahogany and duplicated the upper and lower caps.  Gives the V2 a bit more of a classy look when sitting on a nice desk.  I'll post a pic when I have it reassembled. 
Pics attached.  May not be for everyone, but I like the looks of it.

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